Update libraries (#8155)

* Update libraries

* Fix library names on Unix

* CppCodeGen workaround

* Disabled outdated test

dependencies.props

@@ -3,7 +3,7 @@
     <RyuJITVersion Condition="'$(RyuJITVersion)' == ''">5.0.0-preview.5.20230.9</RyuJITVersion>
     <ObjectWriterVersion Condition="'$(ObjectWriterVersion)' == ''">1.0.0-alpha-28820-01</ObjectWriterVersion>
     <CoreDisToolsVersion Condition="'$(CoreDisToolsVersion)' == ''">1.0.1-prerelease-00005</CoreDisToolsVersion>
-    <RuntimeLibrariesVersion Condition="'$(RuntimeLibrariesVersion)' == ''">5.0.0-preview.2.20153.3</RuntimeLibrariesVersion>
+    <RuntimeLibrariesVersion Condition="'$(RuntimeLibrariesVersion)' == ''">5.0.0-preview.5.20263.12</RuntimeLibrariesVersion>
     <CoreFxUapVersion Condition="'$(CoreFxUapVersion)' == ''">4.7.0-preview6.19265.2</CoreFxUapVersion>
     <MicrosoftNETCoreAppPackageVersion Condition="'$(MicrosoftNETCoreAppPackageVersion)' == ''">2.1.14</MicrosoftNETCoreAppPackageVersion>
     <MicrosoftDotNetTestSdkVersion Condition="'$(MicrosoftDotNetTestSdkVersion)' == ''">15.8.0</MicrosoftDotNetTestSdkVersion>

src/BuildIntegration/Microsoft.NETCore.Native.Unix.props

@@ -57,12 +57,12 @@ See the LICENSE file in the project root for more information.
     <ItemGroup>
       <NativeLibrary Include="$(IlcPath)/sdk/libSystem.Private.CoreLib.Native$(NativeLibraryExtension)" />
       <NativeLibrary Condition="$(NativeCodeGen) == ''" Include="$(IlcPath)/sdk/libSystem.Private.TypeLoader.Native$(NativeLibraryExtension)" />
-      <NativeLibrary Include="$(IlcPath)/framework/System.Native$(NativeLibraryExtension)" />
-      <NativeLibrary Include="$(IlcPath)/framework/System.Globalization.Native$(NativeLibraryExtension)" />
-      <NativeLibrary Include="$(IlcPath)/framework/System.IO.Compression.Native$(NativeLibraryExtension)" />
-      <NativeLibrary Include="$(IlcPath)/framework/System.Net.Security.Native$(NativeLibraryExtension)" />
-      <NativeLibrary Include="$(IlcPath)/framework/System.Security.Cryptography.Native.Apple$(NativeLibraryExtension)" Condition="'$(TargetOS)' == 'OSX'"/>
-      <NativeLibrary Include="$(IlcPath)/framework/System.Security.Cryptography.Native.OpenSsl$(NativeLibraryExtension)" Condition="'$(TargetOS)' != 'OSX'"/>
+      <NativeLibrary Include="$(IlcPath)/framework/libSystem.Native$(NativeLibraryExtension)" />
+      <NativeLibrary Include="$(IlcPath)/framework/libSystem.Globalization.Native$(NativeLibraryExtension)" />
+      <NativeLibrary Include="$(IlcPath)/framework/libSystem.IO.Compression.Native$(NativeLibraryExtension)" />
+      <NativeLibrary Include="$(IlcPath)/framework/libSystem.Net.Security.Native$(NativeLibraryExtension)" />
+      <NativeLibrary Include="$(IlcPath)/framework/libSystem.Security.Cryptography.Native.Apple$(NativeLibraryExtension)" Condition="'$(TargetOS)' == 'OSX'"/>
+      <NativeLibrary Include="$(IlcPath)/framework/libSystem.Security.Cryptography.Native.OpenSsl$(NativeLibraryExtension)" Condition="'$(TargetOS)' != 'OSX'"/>
     </ItemGroup>
 
     <ItemGroup Condition="'$(TargetOS)' == 'OSX'">

src/Common/src/Interop/Interop.Calendar.cs

@@ -5,7 +5,6 @@
 using System;
 using System.Globalization;
 using System.Runtime.InteropServices;
-using System.Text;
 
 internal static partial class Interop
 {

src/Common/src/Interop/Interop.Casing.cs

@@ -2,10 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
-using System.Security;
-using System.Text;
 
 internal static partial class Interop
 {

src/Common/src/Interop/Interop.Collation.cs

@@ -5,7 +5,6 @@
 using System;
 using System.Globalization;
 using System.Runtime.InteropServices;
-using System.Security;
 
 internal static partial class Interop
 {
@@ -24,7 +23,7 @@ internal static partial class Interop
         internal static extern unsafe int IndexOf(IntPtr sortHandle, char* target, int cwTargetLength, char* pSource, int cwSourceLength, CompareOptions options, int* matchLengthPtr);
 
         [DllImport(Libraries.GlobalizationNative, CharSet = CharSet.Unicode, EntryPoint = "GlobalizationNative_LastIndexOf")]
-        internal static extern unsafe int LastIndexOf(IntPtr sortHandle, char* target, int cwTargetLength, char* pSource, int cwSourceLength, CompareOptions options);
+        internal static extern unsafe int LastIndexOf(IntPtr sortHandle, char* target, int cwTargetLength, char* pSource, int cwSourceLength, CompareOptions options, int* matchLengthPtr);
 
         [DllImport(Libraries.GlobalizationNative, CharSet = CharSet.Unicode, EntryPoint = "GlobalizationNative_IndexOfOrdinalIgnoreCase")]
         internal static extern unsafe int IndexOfOrdinalIgnoreCase(string target, int cwTargetLength, char* pSource, int cwSourceLength, bool findLast);

src/Common/src/Interop/Interop.ICU.cs

@@ -2,9 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
-using System.Runtime.CompilerServices;
 
 internal static partial class Interop
 {

src/Common/src/Interop/Interop.Idna.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Interop.Libraries.cs

@@ -0,0 +1,11 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+internal static partial class Interop
+{
+    internal static partial class Libraries
+    {
+        internal const string GlobalizationNative = "libSystem.Globalization.Native";
+    }
+}

src/Common/src/Interop/Interop.Locale.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Interop.Normalization.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
 using System.Text;
 
@@ -11,9 +10,9 @@ internal static partial class Interop
     internal static partial class Globalization
     {
         [DllImport(Libraries.GlobalizationNative, CharSet = CharSet.Unicode, EntryPoint = "GlobalizationNative_IsNormalized")]
-        internal static extern int IsNormalized(NormalizationForm normalizationForm, string src, int srcLen);
+        internal static extern unsafe int IsNormalized(NormalizationForm normalizationForm, char* src, int srcLen);
 
         [DllImport(Libraries.GlobalizationNative, CharSet = CharSet.Unicode, EntryPoint = "GlobalizationNative_NormalizeString")]
-        internal static extern int NormalizeString(NormalizationForm normalizationForm, string src, int srcLen, [Out] char[] dstBuffer, int dstBufferCapacity);
+        internal static extern unsafe int NormalizeString(NormalizationForm normalizationForm, char* src, int srcLen, char* dstBuffer, int dstBufferCapacity);
     }
 }

src/Common/src/Interop/Interop.TimeZoneInfo.cs

@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Runtime.InteropServices;
-using System.Text;
 
 internal static partial class Interop
 {

src/Common/src/Interop/Interop.Utils.cs

@@ -3,9 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using System.Diagnostics;
 using System.Buffers;
-using System.Text;
 
 internal static partial class Interop
 {

src/Common/src/Interop/Unix/Interop.Errors.cs

@@ -115,7 +115,7 @@ internal static partial class Interop
     // Represents a platform-agnostic Error and underlying platform-specific errno
     internal struct ErrorInfo
     {
-        private Error _error;
+        private readonly Error _error;
         private int _rawErrno;
 
         internal ErrorInfo(int errno)

src/Common/src/Interop/Unix/Interop.Libraries.cs

@@ -7,12 +7,12 @@ internal static partial class Interop
     internal static partial class Libraries
     {
         // Shims
-        internal const string SystemNative = "System.Native";
-        internal const string GlobalizationNative = "System.Globalization.Native";
-        internal const string NetSecurityNative = "System.Net.Security.Native";
-        internal const string CryptoNative = "System.Security.Cryptography.Native.OpenSsl";
-        internal const string CompressionNative = "System.IO.Compression.Native";
-        internal const string IOPortsNative = "System.IO.Ports.Native";
+        internal const string SystemNative = "libSystem.Native";
+        internal const string NetSecurityNative = "libSystem.Net.Security.Native";
+        internal const string CryptoNative = "libSystem.Security.Cryptography.Native.OpenSsl";
+        internal const string CompressionNative = "libSystem.IO.Compression.Native";
+        internal const string IOPortsNative = "libSystem.IO.Ports.Native";
         internal const string Libdl = "libdl";
+        internal const string HostPolicy = "libhostpolicy";
     }
 }

src/Common/src/Interop/Unix/System.Native/Interop.Access.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Unix/System.Native/Interop.ChDir.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Unix/System.Native/Interop.EnumerateInterfaceAddresses.cs

@@ -51,8 +51,8 @@ internal static partial class Interop
         [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_EnumerateInterfaceAddresses")]
         public static extern int EnumerateInterfaceAddresses(
             IPv4AddressDiscoveredCallback ipv4Found,
-            IPv6AddressDiscoveredCallback ipv6Found,
-            LinkLayerAddressDiscoveredCallback linkLayerFound);
+            IPv6AddressDiscoveredCallback? ipv6Found,
+            LinkLayerAddressDiscoveredCallback? linkLayerFound);
 
         [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_EnumerateGatewayAddressesForInterface")]
         public static extern int EnumerateGatewayAddressesForInterface(uint interfaceIndex, DnsAddessDiscoveredCallback onGatewayFound);

src/Common/src/Interop/Unix/System.Native/Interop.Fcntl.cs

@@ -17,6 +17,9 @@ internal static partial class Interop
             [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_FcntlSetIsNonBlocking", SetLastError=true)]
             internal static extern int SetIsNonBlocking(SafeHandle fd, int isNonBlocking);
 
+            [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_FcntlGetIsNonBlocking", SetLastError = true)]
+            internal static extern int GetIsNonBlocking(SafeHandle fd, out bool isNonBlocking);
+
             [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_FcntlSetFD", SetLastError=true)]
             internal static extern int SetFD(SafeHandle fd, int flags);
 

src/Common/src/Interop/Unix/System.Native/Interop.GetCpuUtilization.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
-using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Unix/System.Native/Interop.GetEUid.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Unix/System.Native/Interop.GetPid.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Unix/System.Native/Interop.GetPwUid.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Unix/System.Native/Interop.GetRandomBytes.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
-using System.Diagnostics;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Unix/System.Native/Interop.GetSockOpt.cs

@@ -15,5 +15,8 @@ internal static partial class Interop
 
         [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_GetSockOpt")]
         internal static extern unsafe Error GetSockOpt(IntPtr socket, SocketOptionLevel optionLevel, SocketOptionName optionName, byte* optionValue, int* optionLen);
+
+        [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_GetRawSockOpt")]
+        internal static extern unsafe Error GetRawSockOpt(SafeHandle socket, int optionLevel, int optionName, byte* optionValue, int* optionLen);
     }
 }

src/Common/src/Interop/Unix/System.Native/Interop.LockFileRegion.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Unix/System.Native/Interop.MountPoints.FormatInfo.cs

@@ -44,6 +44,7 @@ internal static partial class Interop
             bdevfs = 0x62646576,
             bfs = 0x1BADFACE,
             binfmt_misc = 0x42494E4D,
+            bootfs = 0xA56D3FF9,
             btrfs = 0x9123683E,
             ceph = 0x00C36400,
             cgroupfs = 0x0027E0EB,
@@ -65,6 +66,7 @@ internal static partial class Interop
             ext3 = 0xEF53,
             ext4 = 0xEF53,
             fat = 0x4006,
+            fd = 0xF00D1E,
             fhgfs = 0x19830326,
             fuse = 0x65735546,
             fuseblk = 0x65735546,
@@ -86,6 +88,7 @@ internal static partial class Interop
             jffs2 = 0x72B6,
             jfs = 0x3153464A,
             kafs = 0x6B414653,
+            lofs = 0xEF53, /* loopback filesystem, magic same as ext2 */
             logfs = 0xC97E8168,
             lustre = 0x0BD00BD0,
             minix_old = 0x137F, /* orig. minix */
@@ -227,6 +230,7 @@ internal static partial class Interop
                 case "bdevfs":
                 case "befs":
                 case "bfs":
+                case "bootfs":
                 case "bpf_fs":
                 case "btrfs":
                 case "btrfs_test":
@@ -261,6 +265,7 @@ internal static partial class Interop
                 case "jffs":
                 case "jffs2":
                 case "jfs":
+                case "lofs":
                 case "logfs":
                 case "lxfs":
                 case "minix (30 char.)":
@@ -384,15 +389,18 @@ internal static partial class Interop
                 case "cgroupfs":
                 case "cgroup2fs":
                 case "configfs":
+                case "cpuset":
                 case "cramfs":
                 case "cramfs-wend":
                 case "cryptkeeper":
-                case "cpuset":
+                case "ctfs":
                 case "debugfs":
+                case "dev":
                 case "devfs":
                 case "devpts":
                 case "devtmpfs":
                 case "encfs":
+                case "fd":
                 case "fdesc":
                 case "fuse.gvfsd-fuse":
                 case "fusectl":
@@ -400,9 +408,11 @@ internal static partial class Interop
                 case "hugetlbfs":
                 case "libpam-encfs":
                 case "ibpam-mount":
+                case "mntfs":
+                case "mqueue":
                 case "mtpfs":
                 case "mythtvfs":
-                case "mqueue":
+                case "objfs":
                 case "openprom":
                 case "openpromfs":
                 case "pipefs":
@@ -417,6 +427,7 @@ internal static partial class Interop
                 case "securityfs":
                 case "selinux":
                 case "selinuxfs":
+                case "sharefs":
                 case "sockfs":
                 case "sysfs":
                 case "tmpfs":

src/Common/src/Interop/Unix/System.Native/Interop.MountPoints.cs

@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using System.Collections.Generic;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Unix/System.Native/Interop.PathConf.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
 using System.Runtime.InteropServices;
 
 internal static partial class Interop

src/Common/src/Interop/Unix/System.Native/Interop.Read.cs

@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Runtime.InteropServices;
-using Microsoft.Win32.SafeHandles;
 
 internal static partial class Interop
 {

src/Common/src/Interop/Unix/System.Native/Interop.SetSockOpt.cs

@@ -15,5 +15,8 @@ internal static partial class Interop
 
         [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_SetSockOpt")]
         internal static extern unsafe Error SetSockOpt(IntPtr socket, SocketOptionLevel optionLevel, SocketOptionName optionName, byte* optionValue, int optionLen);
+
+        [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_SetRawSockOpt")]
+        internal static extern unsafe Error SetRawSockOpt(SafeHandle socket, int optionLevel, int optionName, byte* optionValue, int optionLen);
     }
 }

src/Common/src/Interop/Unix/System.Native/Interop.Stat.cs

@@ -55,7 +55,7 @@ internal static partial class Interop
         }
 
         [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_FStat", SetLastError = true)]
-        internal static extern int FStat(SafeFileHandle fd, out FileStatus output);
+        internal static extern int FStat(SafeHandle fd, out FileStatus output);
 
         [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_Stat", SetLastError = true)]
         internal static extern int Stat(string path, out FileStatus output);

src/Common/src/Interop/Unix/System.Native/Interop.SysLog.cs

@@ -19,28 +19,6 @@ internal static partial class Interop
             LOG_NOTICE      = 5,        /* normal but significant condition */
             LOG_INFO        = 6,        /* informational */
             LOG_DEBUG       = 7,        /* debug-level messages */
-            // Facilities
-            LOG_KERN        = (0<<3),   /* kernel messages */
-            LOG_USER        = (1<<3),   /* random user-level messages */
-            LOG_MAIL        = (2<<3),   /* mail system */
-            LOG_DAEMON      = (3<<3),   /* system daemons */
-            LOG_AUTH        = (4<<3),   /* authorization messages */
-            LOG_SYSLOG      = (5<<3),   /* messages generated internally by syslogd */
-            LOG_LPR         = (6<<3),   /* line printer subsystem */
-            LOG_NEWS        = (7<<3),   /* network news subsystem */
-            LOG_UUCP        = (8<<3),   /* UUCP subsystem */
-            LOG_CRON        = (9<<3),   /* clock daemon */
-            LOG_AUTHPRIV    = (10<<3),  /* authorization messages (private) */
-            LOG_FTP         = (11<<3),  /* ftp daemon */
-            // Between FTP and Local is reserved for system use
-            LOG_LOCAL0      = (16<<3),  /* reserved for local use */
-            LOG_LOCAL1      = (17<<3),  /* reserved for local use */
-            LOG_LOCAL2      = (18<<3),  /* reserved for local use */
-            LOG_LOCAL3      = (19<<3),  /* reserved for local use */
-            LOG_LOCAL4      = (20<<3),  /* reserved for local use */
-            LOG_LOCAL5      = (21<<3),  /* reserved for local use */
-            LOG_LOCAL6      = (22<<3),  /* reserved for local use */
-            LOG_LOCAL7      = (23<<3),  /* reserved for local use */
         }
 
         /// <summary>

src/Common/src/Interop/Unix/System.Native/Interop.Write.cs

@@ -2,8 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
 using System.Runtime.InteropServices;
-using Microsoft.Win32.SafeHandles;
 
 internal static partial class Interop
 {
@@ -22,6 +22,6 @@ internal static partial class Interop
         internal static extern unsafe int Write(SafeHandle fd, byte* buffer, int bufferSize);
 
         [DllImport(Libraries.SystemNative, EntryPoint = "SystemNative_Write", SetLastError = true)]
-        internal static extern unsafe int Write(int fd, byte* buffer, int bufferSize);
+        internal static extern unsafe int Write(IntPtr fd, byte* buffer, int bufferSize);
     }
 }

src/Common/src/Interop/Windows/Advapi32/Interop.CryptImportKey.cs

@@ -10,9 +10,9 @@ internal partial class Interop
     internal partial class Advapi32
     {
         [DllImport(Libraries.Advapi32, CharSet = CharSet.Unicode, SetLastError = true)]
-        internal static extern bool CryptImportKey(
+        internal static extern unsafe bool CryptImportKey(
             SafeProvHandle hProv,
-            byte[] pbData,
+            byte* pbData,
             int dwDataLen,
             SafeKeyHandle hPubKey,
             int dwFlags,

src/Common/src/Interop/Windows/Interop.Libraries.cs

@@ -39,5 +39,6 @@ internal static partial class Interop
         internal const string CompressionNative = "clrcompression.dll";
         internal const string CoreWinRT = "api-ms-win-core-winrt-l1-1-0.dll";
         internal const string MsQuic = "msquic.dll";
+        internal const string HostPolicy = "hostpolicy.dll";
     }
 }

src/Common/src/Interop/Windows/Kernel32/Interop.EnumProcessModules.cs

@@ -11,6 +11,6 @@ internal partial class Interop
     internal partial class Kernel32
     {
         [DllImport(Libraries.Kernel32, CharSet = CharSet.Unicode, SetLastError = true, EntryPoint = "K32EnumProcessModules")]
-        internal static extern bool EnumProcessModules(SafeProcessHandle handle, IntPtr modules, int size, ref int needed);
+        internal static extern bool EnumProcessModules(SafeProcessHandle handle, IntPtr[]? modules, int size, out int needed);
     }
 }

src/Common/src/Interop/Windows/Kernel32/Interop.Globalization.cs

@@ -9,6 +9,15 @@ internal static partial class Interop
 {
     internal static unsafe partial class Kernel32
     {
+        // Under debug mode only, we'll want to check the error codes
+        // of some of the p/invokes we make.
+
+#if DEBUG
+        private const bool SetLastErrorForDebug = true;
+#else
+        private const bool SetLastErrorForDebug = false;
+#endif
+
         internal const uint LOCALE_ALLOW_NEUTRAL_NAMES  = 0x08000000; // Flag to allow returning neutral names/lcids for name conversion
         internal const uint LOCALE_ILANGUAGE            = 0x00000001;
         internal const uint LOCALE_SUPPLEMENTAL         = 0x00000002;
@@ -31,6 +40,10 @@ internal static partial class Interop
 
         internal const uint TIME_NOSECONDS = 0x00000002;
 
+        internal const int GEOCLASS_NATION       = 16;
+        internal const int GEO_ISO2              =  4;
+        internal const int GEOID_NOT_AVAILABLE   = -1;
+
         internal const string LOCALE_NAME_USER_DEFAULT = null;
         internal const string LOCALE_NAME_SYSTEM_DEFAULT = "!x-sys-default-locale";
 
@@ -40,7 +53,7 @@ internal static partial class Interop
         [DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
         internal static extern int LocaleNameToLCID(string lpName, uint dwFlags);
 
-        [DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
+        [DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
         internal static extern int LCMapStringEx(
                     string? lpLocaleName,
                     uint dwMapFlags,
@@ -52,7 +65,7 @@ internal static partial class Interop
                     void* lpReserved,
                     IntPtr sortHandle);
 
-        [DllImport("kernel32.dll", EntryPoint = "FindNLSStringEx")]
+        [DllImport("kernel32.dll", EntryPoint = "FindNLSStringEx", SetLastError = SetLastErrorForDebug)]
         internal static extern int FindNLSStringEx(
                     char* lpLocaleName,
                     uint dwFindNLSStringFlags,
@@ -85,14 +98,14 @@ internal static partial class Interop
                     int cchCount2,
                     bool bIgnoreCase);
 
-        [DllImport("kernel32.dll", EntryPoint = "FindStringOrdinal")]
+        [DllImport("kernel32.dll", EntryPoint = "FindStringOrdinal", SetLastError = SetLastErrorForDebug)]
         internal static extern int FindStringOrdinal(
                     uint dwFindStringOrdinalFlags,
                     char* lpStringSource,
                     int cchSource,
                     char* lpStringValue,
                     int cchValue,
-                    int bIgnoreCase);
+                    BOOL bIgnoreCase);
 
         [DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
         internal static extern bool IsNLSDefinedString(
@@ -124,6 +137,12 @@ internal static partial class Interop
         [DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
         internal static extern int GetCalendarInfoEx(string? lpLocaleName, uint Calendar, IntPtr lpReserved, uint CalType, IntPtr lpCalData, int cchData, IntPtr lpValue);
 
+        [DllImport("kernel32.dll")]
+        internal static extern int GetUserGeoID(int geoClass);
+
+        [DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
+        internal static extern int GetGeoInfo(int location, int geoType, char* lpGeoData, int cchData, int LangId);
+
         [DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
         internal static extern bool EnumCalendarInfoExEx(EnumCalendarInfoProcExEx pCalInfoEnumProcExEx, string lpLocaleName, uint Calendar, string? lpReserved, uint CalType, void* lParam);
 

src/Common/src/Interop/Windows/Kernel32/Interop.IsWow64Process_SafeProcessHandle.cs

@@ -10,6 +10,6 @@ internal partial class Interop
     internal partial class Kernel32
     {
         [DllImport(Libraries.Kernel32, SetLastError = true)]
-        internal static extern bool IsWow64Process(SafeProcessHandle hProcess, ref bool Wow64Process);
+        internal static extern bool IsWow64Process(SafeProcessHandle hProcess, out bool Wow64Process);
     }
 }

src/Common/src/Interop/Windows/Normaliz/Interop.Normalization.cs

@@ -3,21 +3,21 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Runtime.InteropServices;
+using System.Text;
 
 internal static partial class Interop
 {
     internal static partial class Normaliz
     {
         [DllImport("Normaliz.dll", CharSet = CharSet.Unicode, SetLastError = true)]
-        internal static extern bool IsNormalizedString(int normForm, string source, int length);
+        internal static extern unsafe BOOL IsNormalizedString(NormalizationForm normForm, char* source, int length);
 
         [DllImport("Normaliz.dll", CharSet = CharSet.Unicode, SetLastError = true)]
-        internal static extern int NormalizeString(
-                                        int normForm,
-                                        string source,
+        internal static extern unsafe int NormalizeString(
+                                        NormalizationForm normForm,
+                                        char* source,
                                         int sourceLength,
-                                        [System.Runtime.InteropServices.OutAttribute]
-                                        char[]? destination,
+                                        char* destination,
                                         int destinationLength);
     }
 }

src/Common/src/Interop/Windows/NtDll/Interop.NtStatus.cs

@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
@@ -7,15 +7,16 @@ internal static partial class Interop
     internal class StatusOptions
     {
         // Error codes from ntstatus.h
-        internal const uint STATUS_SUCCESS = 0x00000000;
-        internal const uint STATUS_SOME_NOT_MAPPED = 0x00000107;
-        internal const uint STATUS_NO_MORE_FILES = 0x80000006;
-        internal const uint STATUS_INVALID_PARAMETER = 0xC000000D;
-        internal const uint STATUS_NO_MEMORY = 0xC0000017;
-        internal const uint STATUS_OBJECT_NAME_NOT_FOUND = 0xC0000034;
-        internal const uint STATUS_NONE_MAPPED = 0xC0000073;
+        internal const uint STATUS_SUCCESS                = 0x00000000;
+        internal const uint STATUS_SOME_NOT_MAPPED        = 0x00000107;
+        internal const uint STATUS_NO_MORE_FILES          = 0x80000006;
+        internal const uint STATUS_INVALID_PARAMETER      = 0xC000000D;
+        internal const uint STATUS_FILE_NOT_FOUND         = 0xC000000F;
+        internal const uint STATUS_NO_MEMORY              = 0xC0000017;
+        internal const uint STATUS_ACCESS_DENIED          = 0xC0000022;
+        internal const uint STATUS_OBJECT_NAME_NOT_FOUND  = 0xC0000034;
+        internal const uint STATUS_ACCOUNT_RESTRICTION    = 0xC000006E;
+        internal const uint STATUS_NONE_MAPPED            = 0xC0000073;
         internal const uint STATUS_INSUFFICIENT_RESOURCES = 0xC000009A;
-        internal const uint STATUS_ACCESS_DENIED = 0xC0000022;
-        internal const uint STATUS_ACCOUNT_RESTRICTION = 0xc000006e;
     }
 }

src/Common/src/Interop/Windows/NtDll/Interop.RtlGetVersion.cs

@@ -18,19 +18,15 @@ internal partial class Interop
             return RtlGetVersion(ref osvi);
         }
 
-        internal static unsafe string RtlGetVersion()
+        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+        internal unsafe struct RTL_OSVERSIONINFOEX
         {
-            const string Version = "Microsoft Windows";
-            if (RtlGetVersionEx(out RTL_OSVERSIONINFOEX osvi) == 0)
-            {
-                return osvi.szCSDVersion[0] != '\0' ?
-                    string.Format("{0} {1}.{2}.{3} {4}", Version, osvi.dwMajorVersion, osvi.dwMinorVersion, osvi.dwBuildNumber, new string(&(osvi.szCSDVersion[0]))) :
-                    string.Format("{0} {1}.{2}.{3}", Version, osvi.dwMajorVersion, osvi.dwMinorVersion, osvi.dwBuildNumber);
-            }
-            else
-            {
-                return Version;
-            }
+            internal uint dwOSVersionInfoSize;
+            internal uint dwMajorVersion;
+            internal uint dwMinorVersion;
+            internal uint dwBuildNumber;
+            internal uint dwPlatformId;
+            internal fixed char szCSDVersion[128];
         }
     }
 }

src/Common/src/System/Diagnostics/NetFrameworkUtils.cs

@@ -220,7 +220,7 @@ namespace System.Diagnostics
                                 StringBuilder installBuilder = new StringBuilder();
                                 installBuilder.Append(installRoot);
                                 if (!installRoot.EndsWith("\\", StringComparison.Ordinal))
-                                    installBuilder.Append("\\");
+                                    installBuilder.Append('\\');
                                 installBuilder.Append(version);
                                 dllDir = installBuilder.ToString();
                             }

src/Common/src/System/Diagnostics/TraceListenerHelpers.cs

@@ -2,11 +2,12 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Diagnostics
 {
     internal static partial class TraceListenerHelpers
     {
-        private static volatile string s_processName;
+        private static volatile string? s_processName;
 
         internal static int GetThreadId()
         {

src/Common/src/System/IO/ChunkedMemoryStream.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
@@ -11,8 +12,8 @@ namespace System.IO
     /// <summary>Provides an in-memory stream composed of non-contiguous chunks.</summary>
     internal sealed class ChunkedMemoryStream : Stream
     {
-        private MemoryChunk _headChunk;
-        private MemoryChunk _currentChunk;
+        private MemoryChunk? _headChunk;
+        private MemoryChunk? _currentChunk;
 
         private const int InitialChunkDefaultSize = 1024;
         private const int MaxChunkSize = 1024 * InitialChunkDefaultSize;
@@ -24,7 +25,7 @@ namespace System.IO
         {
             byte[] result = new byte[_totalLength];
             int offset = 0;
-            for (MemoryChunk chunk = _headChunk; chunk != null; chunk = chunk._next)
+            for (MemoryChunk? chunk = _headChunk; chunk != null; chunk = chunk._next)
             {
                 Debug.Assert(chunk._next == null || chunk._freeOffset == chunk._buffer.Length);
                 Buffer.BlockCopy(chunk._buffer, 0, result, offset, chunk._freeOffset);
@@ -109,7 +110,7 @@ namespace System.IO
         {
             internal readonly byte[] _buffer;
             internal int _freeOffset;
-            internal MemoryChunk _next;
+            internal MemoryChunk? _next;
 
             internal MemoryChunk(int bufferSize) { _buffer = new byte[bufferSize]; }
         }

src/Common/src/System/IO/DelegatingStream.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Diagnostics;
 using System.IO;
 using System.Threading;
@@ -113,7 +114,7 @@ namespace System.Net.Http
             return _innerStream.ReadAsync(buffer, cancellationToken);
         }
 
-        public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
+        public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback? callback, object? state)
         {
             return _innerStream.BeginRead(buffer, offset, count, callback, state);
         }
@@ -167,7 +168,7 @@ namespace System.Net.Http
             return _innerStream.WriteAsync(buffer, cancellationToken);
         }
 
-        public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
+        public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback? callback, object? state)
         {
             return _innerStream.BeginWrite(buffer, offset, count, callback, state);
         }

src/Common/src/System/IO/FileSystem.Attributes.Windows.cs

@@ -81,7 +81,7 @@ namespace System.IO
                         )
                     {
                         // Assert so we can track down other cases (if any) to add to our test suite
-                        Debug.Assert(errorCode == Interop.Errors.ERROR_ACCESS_DENIED || errorCode == Interop.Errors.ERROR_SHARING_VIOLATION,
+                        Debug.Assert(errorCode == Interop.Errors.ERROR_ACCESS_DENIED || errorCode == Interop.Errors.ERROR_SHARING_VIOLATION || errorCode == Interop.Errors.ERROR_SEM_TIMEOUT,
                             $"Unexpected error code getting attributes {errorCode} from path {path}");
 
                         // Files that are marked for deletion will not let you GetFileAttributes,

src/Common/src/System/IO/ReadOnlyMemoryStream.cs

@@ -105,7 +105,7 @@ namespace System.IO
                 new ValueTask<int>(Task.FromCanceled<int>(cancellationToken)) :
                 new ValueTask<int>(Read(buffer.Span));
 
-        public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, object state) =>
+        public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback? callback, object? state) =>
             TaskToApm.Begin(ReadAsync(buffer, offset, count), callback, state);
 
         public override int EndRead(IAsyncResult asyncResult) =>

src/Common/src/System/IO/RowConfigReader.cs

@@ -2,7 +2,9 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 
 namespace System.IO
@@ -47,8 +49,7 @@ namespace System.IO
         /// </summary>
         public string GetNextValue(string key)
         {
-            string value;
-            if (!TryGetNextValue(key, out value))
+            if (!TryGetNextValue(key, out string? value))
             {
                 throw new InvalidOperationException("Couldn't get next value with key " + key);
             }
@@ -62,7 +63,7 @@ namespace System.IO
         /// Tries to get the next occurrence of the given key from the current position of the reader.
         /// If successful, returns true and stores the result in 'value'. Otherwise, returns false.
         /// </summary>
-        public bool TryGetNextValue(string key, out string value)
+        public bool TryGetNextValue(string key, [NotNullWhen(true)] out string? value)
         {
             Debug.Assert(_buffer != null);
             if (_currentIndex >= _buffer.Length)

src/Common/src/System/Runtime/ExceptionServices/ExceptionStackTrace.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Diagnostics;
 using System.Reflection;
 
@@ -16,12 +17,12 @@ namespace System.Runtime.ExceptionServices
             Debug.Assert(exception != null, "Expected non-null Exception");
 
             const string ExceptionRemoteStackTraceStringName = "_remoteStackTraceString";
-            FieldInfo fi = typeof(Exception).GetField(ExceptionRemoteStackTraceStringName, BindingFlags.NonPublic | BindingFlags.Instance);
+            FieldInfo? fi = typeof(Exception).GetField(ExceptionRemoteStackTraceStringName, BindingFlags.NonPublic | BindingFlags.Instance);
 
             if (fi != null)
             {
                 string text =
-                    (string)fi.GetValue(exception) +
+                    (string?)fi.GetValue(exception) +
                     Environment.StackTrace + Environment.NewLine +
                     "--- End of stack trace from AddCurrentStack ---" + Environment.NewLine;
                 fi.SetValue(exception, text);

src/Common/src/System/StrongToWeakReference.cs

@@ -9,7 +9,7 @@ namespace System
     /// <summary>Provides an object wrapper that can transition between strong and weak references to the object.</summary>
     internal sealed class StrongToWeakReference<T> : WeakReference where T : class
     {
-        private T _strongRef;
+        private T? _strongRef;
 
         /// <summary>Initializes the instance with a strong reference to the specified object.</summary>
         /// <param name="obj">The object to wrap.</param>
@@ -30,9 +30,9 @@ namespace System
         }
 
         /// <summary>Gets the wrapped object.</summary>
-        public new T Target => _strongRef ?? WeakTarget;
+        public new T? Target => _strongRef ?? WeakTarget;
 
         /// <summary>Gets the wrapped object via its weak reference.</summary>
-        private T WeakTarget => base.Target as T;
+        private T? WeakTarget => base.Target as T;
     }
 }

src/Common/src/System/Text/StringBuilderCache.cs

@@ -11,7 +11,7 @@ namespace System.Text
         // The value 360 was chosen in discussion with performance experts as a compromise between using
         // as litle memory per thread as possible and still covering a large part of short-lived
         // StringBuilder creations on the startup path of VS designers.
-        private const int MaxBuilderSize = 360;
+        internal const int MaxBuilderSize = 360;
         private const int DefaultCapacity = 16; // == StringBuilder.DefaultCapacity
 
         // WARNING: We allow diagnostic tools to directly inspect this member (t_cachedInstance).

src/Common/src/System/Threading/Tasks/RendezvousAwaitable.cs

@@ -2,7 +2,9 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Runtime.ExceptionServices;
 
@@ -19,11 +21,11 @@ namespace System.Threading.Tasks
         /// The continuation to invoke when the operation completes, or <see cref="s_completionSentinel"/> if the operation
         /// has completed before OnCompleted is called.
         /// </summary>
-        private Action _continuation;
+        private Action? _continuation;
         /// <summary>The exception representing the failed async operation, if it failed.</summary>
-        private ExceptionDispatchInfo _error;
+        private ExceptionDispatchInfo? _error;
         /// <summary>The result of the async operation, if it succeeded.</summary>
-        private TResult _result;
+        [AllowNull] private TResult _result = default;
 #if DEBUG
         private bool _resultSet;
 #endif
@@ -39,7 +41,7 @@ namespace System.Threading.Tasks
         {
             get
             {
-                Action c = Volatile.Read(ref _continuation);
+                Action? c = Volatile.Read(ref _continuation);
                 Debug.Assert(c == null || c == s_completionSentinel);
                 return c != null;
             }
@@ -55,7 +57,7 @@ namespace System.Threading.Tasks
 
             // Propagate any error if there is one, clearing it out first to prepare for reuse.
             // We don't need to clear a result, as result and error are mutually exclusive.
-            ExceptionDispatchInfo error = _error;
+            ExceptionDispatchInfo? error = _error;
             if (error != null)
             {
                 _error = null;
@@ -101,7 +103,7 @@ namespace System.Threading.Tasks
         /// <summary>Alerts any awaiter that the operation has completed.</summary>
         private void NotifyAwaiter()
         {
-            Action c = _continuation ?? Interlocked.CompareExchange(ref _continuation, s_completionSentinel, null);
+            Action? c = _continuation ?? Interlocked.CompareExchange(ref _continuation, s_completionSentinel, null);
             if (c != null)
             {
                 Debug.Assert(c != s_completionSentinel);
@@ -122,7 +124,7 @@ namespace System.Threading.Tasks
         {
             Debug.Assert(continuation != null);
 
-            Action c = _continuation ?? Interlocked.CompareExchange(ref _continuation, continuation, null);
+            Action? c = _continuation ?? Interlocked.CompareExchange(ref _continuation, continuation, null);
             if (c != null)
             {
                 Debug.Assert(c == s_completionSentinel);

src/Framework/Framework.depproj

@@ -71,6 +71,8 @@
       <_filteredNuGetDeployByFileName Include="@(_nuGetDeployByFileName)" Condition="'%(Identity)' == 'netstandard'" />
       <_filteredNuGetDeployByFileName Include="@(_nuGetDeployByFileName)" Condition="'%(Identity)' == 'mscorlib'" />
 
+      <_filteredNuGetDeployByFileName Include="@(_nuGetDeployByFileName)" Condition="$([System.String]::new('%(Identity)').StartsWith('libSystem'))" />
+
       <!-- TODO: https://github.com/dotnet/corert/issues/5496 -->
       <_filteredNuGetDeployByFileName Include="@(_nuGetDeployByFileName)" Condition="'%(Identity)' == 'clrcompression'" />
 

src/ILCompiler.CppCodeGen/src/CppCodeGen/CppWriter.cs

@@ -589,6 +589,16 @@ namespace ILCompiler.CppCodeGen
             sb.AppendLine();
             AppendCppMethodDeclaration(sb, method, true);
             sb.AppendLine();
+
+            // TODO: workaround unreachable globalization methods
+            string moduleName = method.GetPInvokeMethodMetadata().Module;
+            if (moduleName == (_compilation.TypeSystemContext.Target.IsWindows ? "libSystem.Globalization.Native" : "kernel32.dll"))
+            {
+                sb.Append("{ throw 0; }");
+                methodCodeNodeNeedingCode.SetCode(sb.ToString(), Array.Empty<Object>());
+                return;
+            }
+
             sb.Append("{");
             sb.Indent();
 

src/ILCompiler/src/ConfigurablePInvokePolicy.cs

@@ -71,7 +71,7 @@ namespace ILCompiler
             else
             {
                 // Account for System.Private.CoreLib.Native / System.Globalization.Native / System.Native / etc
-                return importModule.StartsWith("System.");
+                return importModule.StartsWith("libSystem.");
             }
         }
     }

src/System.Private.CoreLib/shared/Internal/Resources/WindowsRuntimeResourceManagerBase.cs

@@ -12,7 +12,7 @@ namespace Internal.Resources
     {
         public abstract bool Initialize(string libpath, string reswFilename, out PRIExceptionInfo? exceptionInfo);
 
-        public abstract string GetString(string stringName, string? startingCulture, string? neutralResourcesCulture);
+        public abstract string? GetString(string stringName, string? startingCulture, string? neutralResourcesCulture);
 
         public abstract CultureInfo? GlobalResourceContextBestFitCultureInfo
         {

src/System.Private.CoreLib/shared/Microsoft/Win32/SafeHandles/SafeFileHandle.Unix.cs

@@ -5,7 +5,6 @@
 using System;
 using System.Diagnostics;
 using System.IO;
-using System.Runtime.InteropServices;
 
 namespace Microsoft.Win32.SafeHandles
 {

src/System.Private.CoreLib/shared/System.Private.CoreLib.Shared.projitems

@@ -149,6 +149,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\IReadOnlyDictionary.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\IReadOnlyList.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\ISet.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\IReadOnlySet.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\KeyNotFoundException.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\KeyValuePair.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Collections\Generic\List.cs" />
@@ -239,16 +240,24 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\Calendar.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CalendarAlgorithmType.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CalendarData.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CalendarData.Icu.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CalendarData.Nls.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CalendarWeekRule.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CalendricalCalculationsHelper.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CharUnicodeInfo.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CharUnicodeInfoData.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\ChineseLunisolarCalendar.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CompareInfo.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CompareInfo.Icu.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CompareInfo.Invariant.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CompareInfo.Nls.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CompareOptions.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureData.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureData.Icu.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureData.Nls.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureInfo.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureInfo.Icu.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureInfo.Nls.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureNotFoundException.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureTypes.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\DateTimeFormat.cs" />
@@ -266,14 +275,22 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\HebrewCalendar.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\HebrewNumber.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\HijriCalendar.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\IcuLocaleData.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\IdnMapping.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\IdnMapping.Icu.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\IdnMapping.Nls.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\InternalGlobalizationHelper.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\ISOWeek.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\JapaneseCalendar.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\JapaneseCalendar.Icu.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\JapaneseCalendar.Nls.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\JapaneseLunisolarCalendar.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\JulianCalendar.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\KoreanCalendar.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\KoreanLunisolarCalendar.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\Normalization.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\Normalization.Icu.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\Normalization.Nls.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\NumberFormatInfo.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\NumberStyles.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\PersianCalendar.cs" />
@@ -286,6 +303,8 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\TaiwanLunisolarCalendar.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\TextElementEnumerator.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\TextInfo.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\TextInfo.Icu.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\TextInfo.Nls.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\ThaiBuddhistCalendar.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\TimeSpanFormat.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\TimeSpanParse.cs" />
@@ -477,6 +496,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Reflection\Emit\SignatureToken.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Reflection\Emit\StackBehaviour.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Reflection\Emit\StringToken.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Reflection\Emit\TypeNameBuilder.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Reflection\Emit\TypeToken.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Reflection\EventAttributes.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Reflection\EventInfo.cs" />
@@ -735,7 +755,6 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\Intrinsics\Vector64_1.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\Intrinsics\Vector64DebugView_1.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\Intrinsics\X86\Enums.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\Loader\AssemblyDependencyResolver.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\Loader\AssemblyLoadContext.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\Loader\LibraryNameVariation.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\MemoryFailPoint.cs" />
@@ -859,7 +878,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\Unicode\Utf8Utility.Helpers.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\Unicode\Utf8Utility.Transcoding.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\Unicode\Utf8Utility.Validation.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Text\Unicode\Utf8Utility.WhiteSpace.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Text\Unicode\Utf8Utility.WhiteSpace.CoreLib.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\UnicodeDebug.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\UnicodeEncoding.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Text\UnicodeUtility.cs" />
@@ -967,12 +986,64 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\UnauthorizedAccessException.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\UnhandledExceptionEventArgs.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\UnhandledExceptionEventHandler.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\UnitySerializationHolder.cs"/>
+    <Compile Include="$(MSBuildThisFileDirectory)System\UnitySerializationHolder.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\ValueTuple.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Version.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Void.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\WeakReference.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\WeakReference.T.cs" />
+    <Compile Include="$(CommonPath)Interop\Interop.Libraries.cs">
+      <Link>Common\Interop\Interop.Libraries.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Interop.Calendar.cs">
+      <Link>Common\Interop\Interop.Calendar.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Interop.Casing.cs">
+      <Link>Common\Interop\Interop.Casing.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Interop.Collation.cs">
+      <Link>Common\Interop\Interop.Collation.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Interop.ICU.cs">
+      <Link>Common\Interop\Interop.ICU.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Interop.Idna.cs">
+      <Link>Common\Interop\Interop.Idna.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Interop.Locale.cs">
+      <Link>Common\Interop\Interop.Locale.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Interop.Normalization.cs">
+      <Link>Common\Interop\Interop.Normalization.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Interop.ResultCode.cs">
+      <Link>Common\Interop\Interop.ResultCode.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Interop.TimeZoneInfo.cs">
+      <Link>Common\Interop\Interop.TimeZoneInfo.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Interop.Utils.cs">
+      <Link>Common\Interop\Interop.Utils.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Windows\Interop.Errors.cs">
+      <Link>Common\Interop\Interop.Errors.cs</Link>
+    </Compile>
+    <!-- The CLR internally uses a BOOL type analogous to the Windows BOOL type on Unix -->
+    <Compile Include="$(CommonPath)Interop\Windows\Interop.BOOL.cs">
+      <Link>Common\Interop\Windows\Interop.BOOL.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.Globalization.cs">
+      <Link>Common\Interop\Windows\Kernel32\Interop.Globalization.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.ResolveLocaleName.cs">
+      <Link>Common\Interop\Windows\Kernel32\Interop.ResolveLocaleName.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Windows\Normaliz\Interop.Idna.cs">
+      <Link>Common\Interop\Windows\Normaliz\Interop.Idna.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)Interop\Windows\Normaliz\Interop.Normalization.cs">
+      <Link>Common\Interop\Windows\Normaliz\Interop.Normalization.cs</Link>
+    </Compile>
     <Compile Include="$(CommonPath)System\HResults.cs">
       <Link>Common\System\HResults.cs</Link>
     </Compile>
@@ -1018,6 +1089,11 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\EventActivityOptions.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\EventCounter.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\EventDescriptor.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\EventPipe.cs" Condition="'$(FeaturePerfTracing)' == 'true'" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\EventPipeEventDispatcher.cs" Condition="'$(FeaturePerfTracing)' == 'true'" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\EventPipeEventProvider.cs" Condition="'$(FeaturePerfTracing)' == 'true'" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\EventPipeMetadataGenerator.cs" Condition="'$(FeaturePerfTracing)' == 'true'" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\EventPipePayloadDecoder.cs" Condition="'$(FeaturePerfTracing)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\EventProvider.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\EventSource.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\EventSourceException.cs" />
@@ -1025,7 +1101,9 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\IEventProvider.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\IncrementingEventCounter.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\IncrementingPollingCounter.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\NativeRuntimeEventSource.cs" Condition="'$(FeaturePerfTracing)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\PollingCounter.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\RuntimeEventSource.cs" Condition="'$(FeaturePerfTracing)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\StubEnvironment.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\Winmeta.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\ArrayTypeInfo.cs" />
@@ -1052,12 +1130,14 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\Statics.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\TraceLoggingDataCollector.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\TraceLoggingDataType.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\TraceLoggingEventHandleTable.cs" Condition="'$(FeaturePerfTracing)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\TraceLoggingEventSource.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\TraceLoggingEventTraits.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\TraceLoggingEventTypes.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\TraceLoggingMetadataCollector.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\TraceLoggingTypeInfo.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\TypeAnalysis.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\TraceLogging\XplatEventLogger.cs" Condition="'$(FeatureXplatEventSource)' == 'true'" />
   </ItemGroup>
   <ItemGroup>
     <Compile Include="$(MSBuildThisFileDirectory)\..\..\Common\src\System\HexConverter.cs">
@@ -1165,9 +1245,6 @@
     <Compile Include="$(CommonPath)Interop\Windows\Crypt32\Interop.CryptProtectMemory.cs">
       <Link>Common\Interop\Windows\Crypt32\Interop.CryptProtectMemory.cs</Link>
     </Compile>
-    <Compile Include="$(CommonPath)Interop\Windows\Interop.BOOL.cs">
-      <Link>Common\Interop\Windows\Interop.BOOL.cs</Link>
-    </Compile>
     <Compile Include="$(CommonPath)Interop\Windows\Interop.BOOLEAN.cs">
       <Link>Common\Interop\Windows\Interop.BOOLEAN.cs</Link>
     </Compile>
@@ -1282,12 +1359,6 @@
     <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.GetTempPathW.cs">
       <Link>Common\Interop\Windows\Kernel32\Interop.GetTempPathW.cs</Link>
     </Compile>
-    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.GetVersionExW.cs">
-      <Link>Common\Interop\Windows\Kernel32\Interop.GetVersionExW.cs</Link>
-    </Compile>
-    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.Globalization.cs">
-      <Link>Common\Interop\Windows\Kernel32\Interop.Globalization.cs</Link>
-    </Compile>
     <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.GlobalMemoryStatusEx.cs">
       <Link>Common\Interop\Windows\Kernel32\Interop.GlobalMemoryStatusEx.cs</Link>
     </Compile>
@@ -1336,9 +1407,6 @@
     <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.ReadFile_SafeHandle_NativeOverlapped.cs">
       <Link>Common\Interop\Windows\Kernel32\Interop.ReadFile_SafeHandle_NativeOverlapped.cs</Link>
     </Compile>
-    <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.ResolveLocaleName.cs">
-      <Link>Common\Interop\Windows\Kernel32\Interop.ResolveLocaleName.cs</Link>
-    </Compile>
     <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.SECURITY_ATTRIBUTES.cs">
       <Link>Common\Interop\Windows\Kernel32\Interop.SECURITY_ATTRIBUTES.cs</Link>
     </Compile>
@@ -1399,18 +1467,15 @@
     <Compile Include="$(CommonPath)Interop\Windows\Kernel32\Interop.WriteFile_SafeHandle_NativeOverlapped.cs">
       <Link>Common\Interop\Windows\Kernel32\Interop.WriteFile_SafeHandle_NativeOverlapped.cs</Link>
     </Compile>
-    <Compile Include="$(CommonPath)Interop\Windows\Normaliz\Interop.Idna.cs">
-      <Link>Common\Interop\Windows\Normaliz\Interop.Idna.cs</Link>
-    </Compile>
-    <Compile Include="$(CommonPath)Interop\Windows\Normaliz\Interop.Normalization.cs">
-      <Link>Common\Interop\Windows\Normaliz\Interop.Normalization.cs</Link>
-    </Compile>
     <Compile Include="$(CommonPath)Interop\Windows\NtDll\Interop.NtQueryInformationFile.cs">
       <Link>Common\Interop\Windows\NtDll\Interop.NtQueryInformationFile.cs</Link>
     </Compile>
     <Compile Include="$(CommonPath)Interop\Windows\NtDll\Interop.NtQuerySystemInformation.cs">
       <Link>Common\Interop\Windows\NtDll\Interop.NtQuerySystemInformation.cs</Link>
     </Compile>
+    <Compile Include="$(CommonPath)Interop\Windows\NtDll\Interop.RtlGetVersion.cs">
+      <Link>Common\Interop\Windows\NtDll\Interop.RtlGetVersion.cs</Link>
+    </Compile>
     <Compile Include="$(CommonPath)Interop\Windows\NtDll\Interop.SYSTEM_LEAP_SECOND_INFORMATION.cs">
       <Link>Common\Interop\Windows\NtDll\Interop.SYSTEM_LEAP_SECOND_INFORMATION.cs</Link>
     </Compile>
@@ -1455,15 +1520,8 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.Windows.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\DebugProvider.Windows.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Stopwatch.Windows.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CalendarData.Windows.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureInfo.Windows.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CompareInfo.Windows.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureData.Windows.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\RuntimeEventSourceHelper.Windows.cs" Condition="'$(FeaturePerfTracing)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\HijriCalendar.Win32.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\IdnMapping.Windows.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\JapaneseCalendar.Win32.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\Normalization.Windows.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\TextInfo.Windows.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Guid.Windows.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\DriveInfoInternal.Windows.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileStream.Windows.cs" />
@@ -1486,6 +1544,9 @@
   <ItemGroup Condition="'$(FeatureAsyncCausalityTracer)' != 'true'">
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\Tasks\AsyncCausalityTracer.Noop.cs" />
   </ItemGroup>
+  <ItemGroup Condition="'$(FeatureComWrappers)' != 'true'">
+    <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\InteropServices\ComWrappers.PlatformNotSupported.cs" />
+  </ItemGroup>
   <ItemGroup Condition="'$(FeatureCominterop)' != 'true'">
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\InteropServices\Marshal.NoCom.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\InteropServices\ComEventsHelpers.NoCom.cs" />
@@ -1500,7 +1561,6 @@
   <!-- CoreCLR uses PAL layer that emulates Windows API on Unix. This is bridge for that PAL layer. See issue dotnet/runtime/#31721. -->
   <ItemGroup Condition="'$(TargetsWindows)' == 'true' or '$(FeatureCoreCLR)'=='true'">
     <Compile Include="$(MSBuildThisFileDirectory)Microsoft\Win32\SafeHandles\SafeWaitHandle.Windows.cs" />
-    <Compile Include="$(CommonPath)Interop\Windows\Interop.Errors.cs" />
     <Compile Include="$(CommonPath)Interop\Windows\OleAut32\Interop.SysAllocStringLen.cs">
       <Link>Common\Interop\Windows\OleAut32\Interop.SysAllocStringLen.cs</Link>
     </Compile>
@@ -1545,7 +1605,7 @@
     </Compile>
     <Compile Include="$(CommonPath)System\IO\Win32Marshal.cs">
       <Link>Common\System\IO\Win32Marshal.cs</Link>
-    </Compile>      
+    </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.Variables.Windows.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\Mutex.Windows.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\Semaphore.Windows.cs" />
@@ -1566,36 +1626,6 @@
     <Compile Include="$(CommonPath)Interop\Unix\Interop.Libraries.cs">
       <Link>Common\Interop\Unix\Interop.Libraries.cs</Link>
     </Compile>
-    <Compile Include="$(CommonPath)Interop\Unix\System.Globalization.Native\Interop.Calendar.cs">
-      <Link>Common\Interop\Unix\System.Globalization.Native\Interop.Calendar.cs</Link>
-    </Compile>
-    <Compile Include="$(CommonPath)Interop\Unix\System.Globalization.Native\Interop.Casing.cs">
-      <Link>Common\Interop\Unix\System.Globalization.Native\Interop.Casing.cs</Link>
-    </Compile>
-    <Compile Include="$(CommonPath)Interop\Unix\System.Globalization.Native\Interop.Collation.cs">
-      <Link>Common\Interop\Unix\System.Globalization.Native\Interop.Collation.cs</Link>
-    </Compile>
-    <Compile Include="$(CommonPath)Interop\Unix\System.Globalization.Native\Interop.ICU.cs">
-      <Link>Common\Interop\Unix\System.Globalization.Native\Interop.ICU.cs</Link>
-    </Compile>
-    <Compile Include="$(CommonPath)Interop\Unix\System.Globalization.Native\Interop.Idna.cs">
-      <Link>Common\Interop\Unix\System.Globalization.Native\Interop.Idna.cs</Link>
-    </Compile>
-    <Compile Include="$(CommonPath)Interop\Unix\System.Globalization.Native\Interop.Locale.cs">
-      <Link>Common\Interop\Unix\System.Globalization.Native\Interop.Locale.cs</Link>
-    </Compile>
-    <Compile Include="$(CommonPath)Interop\Unix\System.Globalization.Native\Interop.Normalization.cs">
-      <Link>Common\Interop\Unix\System.Globalization.Native\Interop.Normalization.cs</Link>
-    </Compile>
-    <Compile Include="$(CommonPath)Interop\Unix\System.Globalization.Native\Interop.ResultCode.cs">
-      <Link>Common\Interop\Unix\System.Globalization.Native\Interop.ResultCode.cs</Link>
-    </Compile>
-    <Compile Include="$(CommonPath)Interop\Unix\System.Globalization.Native\Interop.TimeZoneInfo.cs">
-      <Link>Common\Interop\Unix\System.Globalization.Native\Interop.TimeZoneInfo.cs</Link>
-    </Compile>
-    <Compile Include="$(CommonPath)Interop\Unix\System.Globalization.Native\Interop.Utils.cs">
-      <Link>Common\Interop\Unix\System.Globalization.Native\Interop.Utils.cs</Link>
-    </Compile>
     <Compile Include="$(CommonPath)Interop\Unix\System.Native\Interop.Access.cs">
       <Link>Common\Interop\Unix\System.Native\Interop.Access.cs</Link>
     </Compile>
@@ -1705,22 +1735,15 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\DateTime.Unix.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\DebugProvider.Unix.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Stopwatch.Unix.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Diagnostics\Tracing\RuntimeEventSourceHelper.Unix.cs" Condition="'$(FeaturePerfTracing)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.NoRegistry.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Environment.Unix.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CalendarData.Unix.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CompareInfo.Unix.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureData.Unix.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureInfo.Unix.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Environment.Unix.GetFolderPathCore.cs" Condition="'$(TargetsiOS)' != 'true' and '$(TargetstvOS)' != 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\HijriCalendar.Unix.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\IdnMapping.Unix.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\JapaneseCalendar.Unix.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\LocaleData.Unix.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\Normalization.Unix.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\TextInfo.Unix.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Guid.Unix.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\DriveInfoInternal.Unix.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileStream.OSX.cs" Condition="'$(TargetsOSX)' == 'true'" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileStream.Linux.cs" Condition="'$(TargetsOSX)' != 'true'" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileStream.OSX.cs" Condition="'$(TargetsOSX)' == 'true' or '$(TargetsiOS)' == 'true' or '$(TargetstvOS)' == 'true'" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileStream.Linux.cs" Condition="'$(TargetsOSX)' != 'true' and '$(TargetsiOS)' != 'true' and '$(TargetstvOS)' != 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\FileStream.Unix.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\Path.Unix.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IO\PathInternal.Unix.cs" />

src/System.Private.CoreLib/shared/System/AppContext.cs

@@ -22,7 +22,7 @@ namespace System
         public static string BaseDirectory =>
             // The value of APP_CONTEXT_BASE_DIRECTORY key has to be a string and it is not allowed to be any other type.
             // Otherwise the caller will get invalid cast exception
-            (string?)GetData("APP_CONTEXT_BASE_DIRECTORY") ??
+            GetData("APP_CONTEXT_BASE_DIRECTORY") as string ??
             (s_defaultBaseDirectory ??= GetBaseDirectoryCore());
 
         public static string? TargetFrameworkName =>

src/System.Private.CoreLib/shared/System/AppContextConfigHelper.cs

@@ -12,7 +12,7 @@ namespace System
         {
             try
             {
-                object config = AppContext.GetData(configName);
+                object? config = AppContext.GetData(configName);
                 int result = defaultValue;
                 switch (config)
                 {
@@ -54,7 +54,7 @@ namespace System
         {
             try
             {
-                object config = AppContext.GetData(configName);
+                object? config = AppContext.GetData(configName);
                 short result = defaultValue;
                 switch (config)
                 {

src/System.Private.CoreLib/shared/System/AppDomain.cs

@@ -149,8 +149,7 @@ namespace System
 
         public bool? IsCompatibilitySwitchSet(string value)
         {
-            bool result;
-            return AppContext.TryGetSwitch(value, out result) ? result : default(bool?);
+            return AppContext.TryGetSwitch(value, out bool result) ? result : default(bool?);
         }
 
         public bool IsDefaultAppDomain() => true;

src/System.Private.CoreLib/shared/System/Array.cs

@@ -7,6 +7,7 @@ using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
+using System.Numerics;
 using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -26,6 +27,11 @@ namespace System
         internal const int MaxArrayLength = 0X7FEFFFFF;
         internal const int MaxByteArrayLength = 0x7FFFFFC7;
 
+        // This is the threshold where Introspective sort switches to Insertion sort.
+        // Empirically, 16 seems to speed up most cases without slowing down others, at least for integers.
+        // Large value types may benefit from a smaller number.
+        internal const int IntrosortSizeThreshold = 16;
+
         // This ctor exists solely to prevent C# from generating a protected .ctor that violates the surface area.
         private protected Array() { }
 
@@ -510,9 +516,7 @@ namespace System
             if (comparer == Comparer.Default)
             {
                 CorElementType et = array.GetCorElementTypeOfElementType();
-                if (et.IsPrimitiveType()
-                    // IntPtr/UIntPtr does not implement IComparable
-                    && (et != CorElementType.ELEMENT_TYPE_I) && (et != CorElementType.ELEMENT_TYPE_U))
+                if (et.IsPrimitiveType())
                 {
                     if (value == null)
                         return ~index;
@@ -538,15 +542,27 @@ namespace System
                                 result = GenericBinarySearch<ushort>(array, adjustedIndex, length, value);
                                 break;
                             case CorElementType.ELEMENT_TYPE_I4:
+#if TARGET_32BIT
+                            case CorElementType.ELEMENT_TYPE_I:
+#endif
                                 result = GenericBinarySearch<int>(array, adjustedIndex, length, value);
                                 break;
                             case CorElementType.ELEMENT_TYPE_U4:
+#if TARGET_32BIT
+                            case CorElementType.ELEMENT_TYPE_U:
+#endif
                                 result = GenericBinarySearch<uint>(array, adjustedIndex, length, value);
                                 break;
                             case CorElementType.ELEMENT_TYPE_I8:
+#if TARGET_64BIT
+                            case CorElementType.ELEMENT_TYPE_I:
+#endif
                                 result = GenericBinarySearch<long>(array, adjustedIndex, length, value);
                                 break;
                             case CorElementType.ELEMENT_TYPE_U8:
+#if TARGET_64BIT
+                            case CorElementType.ELEMENT_TYPE_U:
+#endif
                                 result = GenericBinarySearch<ulong>(array, adjustedIndex, length, value);
                                 break;
                             case CorElementType.ELEMENT_TYPE_R4:
@@ -1674,15 +1690,27 @@ namespace System
                             GenericSort<ushort>(keys, items, adjustedIndex, length);
                             return;
                         case CorElementType.ELEMENT_TYPE_I4:
+#if TARGET_32BIT
+                        case CorElementType.ELEMENT_TYPE_I:
+#endif
                             GenericSort<int>(keys, items, adjustedIndex, length);
                             return;
                         case CorElementType.ELEMENT_TYPE_U4:
+#if TARGET_32BIT
+                        case CorElementType.ELEMENT_TYPE_U:
+#endif
                             GenericSort<uint>(keys, items, adjustedIndex, length);
                             return;
                         case CorElementType.ELEMENT_TYPE_I8:
+#if TARGET_64BIT
+                        case CorElementType.ELEMENT_TYPE_I:
+#endif
                             GenericSort<long>(keys, items, adjustedIndex, length);
                             return;
                         case CorElementType.ELEMENT_TYPE_U8:
+#if TARGET_64BIT
+                        case CorElementType.ELEMENT_TYPE_U:
+#endif
                             GenericSort<ulong>(keys, items, adjustedIndex, length);
                             return;
                         case CorElementType.ELEMENT_TYPE_R4:
@@ -1691,10 +1719,6 @@ namespace System
                         case CorElementType.ELEMENT_TYPE_R8:
                             GenericSort<double>(keys, items, adjustedIndex, length);
                             return;
-                        case CorElementType.ELEMENT_TYPE_I:
-                        case CorElementType.ELEMENT_TYPE_U:
-                            // IntPtr/UIntPtr does not implement IComparable
-                            break;
                     }
 
                     static void GenericSort<T>(Array keys, Array? items, int adjustedIndex, int length) where T: struct
@@ -1898,11 +1922,11 @@ namespace System
 
                 try
                 {
-                    IntroSort(left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(length));
+                    IntroSort(left, length + left - 1, 2 * (BitOperations.Log2((uint)length) + 1));
                 }
                 catch (IndexOutOfRangeException)
                 {
-                    IntrospectiveSortUtilities.ThrowOrIgnoreBadComparer(comparer);
+                    ThrowHelper.ThrowArgumentException_BadComparer(comparer);
                 }
                 catch (Exception e)
                 {
@@ -1912,20 +1936,22 @@ namespace System
 
             private void IntroSort(int lo, int hi, int depthLimit)
             {
+                Debug.Assert(hi >= lo);
+                Debug.Assert(depthLimit >= 0);
+
                 while (hi > lo)
                 {
                     int partitionSize = hi - lo + 1;
-                    if (partitionSize <= IntrospectiveSortUtilities.IntrosortSizeThreshold)
+                    if (partitionSize <= IntrosortSizeThreshold)
                     {
-                        if (partitionSize == 1)
-                        {
-                            return;
-                        }
+                        Debug.Assert(partitionSize >= 2);
+
                         if (partitionSize == 2)
                         {
                             SwapIfGreater(lo, hi);
                             return;
                         }
+
                         if (partitionSize == 3)
                         {
                             SwapIfGreater(lo, hi - 1);
@@ -1953,8 +1979,11 @@ namespace System
 
             private int PickPivotAndPartition(int lo, int hi)
             {
+                Debug.Assert(hi - lo >= IntrosortSizeThreshold);
+
                 // Compute median-of-three.  But also partition them, since we've done the comparison.
                 int mid = lo + (hi - lo) / 2;
+
                 // Sort lo, mid and hi appropriately, then pick mid as the pivot.
                 SwapIfGreater(lo, mid);
                 SwapIfGreater(lo, hi);
@@ -1976,7 +2005,10 @@ namespace System
                 }
 
                 // Put pivot in the right location.
-                Swap(left, hi - 1);
+                if (left != hi - 1)
+                {
+                    Swap(left, hi - 1);
+                }
                 return left;
             }
 
@@ -2104,11 +2136,11 @@ namespace System
 
                 try
                 {
-                    IntroSort(left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(length));
+                    IntroSort(left, length + left - 1, 2 * (BitOperations.Log2((uint)length) + 1));
                 }
                 catch (IndexOutOfRangeException)
                 {
-                    IntrospectiveSortUtilities.ThrowOrIgnoreBadComparer(comparer);
+                    ThrowHelper.ThrowArgumentException_BadComparer(comparer);
                 }
                 catch (Exception e)
                 {
@@ -2118,20 +2150,22 @@ namespace System
 
             private void IntroSort(int lo, int hi, int depthLimit)
             {
+                Debug.Assert(hi >= lo);
+                Debug.Assert(depthLimit >= 0);
+
                 while (hi > lo)
                 {
                     int partitionSize = hi - lo + 1;
-                    if (partitionSize <= IntrospectiveSortUtilities.IntrosortSizeThreshold)
+                    if (partitionSize <= IntrosortSizeThreshold)
                     {
-                        if (partitionSize == 1)
-                        {
-                            return;
-                        }
+                        Debug.Assert(partitionSize >= 2);
+
                         if (partitionSize == 2)
                         {
                             SwapIfGreater(lo, hi);
                             return;
                         }
+
                         if (partitionSize == 3)
                         {
                             SwapIfGreater(lo, hi - 1);
@@ -2159,6 +2193,8 @@ namespace System
 
             private int PickPivotAndPartition(int lo, int hi)
             {
+                Debug.Assert(hi - lo >= IntrosortSizeThreshold);
+
                 // Compute median-of-three.  But also partition them, since we've done the comparison.
                 int mid = lo + (hi - lo) / 2;
 
@@ -2182,7 +2218,10 @@ namespace System
                 }
 
                 // Put pivot in the right location.
-                Swap(left, hi - 1);
+                if (left != hi - 1)
+                {
+                    Swap(left, hi - 1);
+                }
                 return left;
             }
 

src/System.Private.CoreLib/shared/System/BitConverter.cs

@@ -4,6 +4,8 @@
 
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.X86;
 
 using Internal.Runtime.CompilerServices;
 
@@ -449,24 +451,52 @@ namespace System
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static unsafe long DoubleToInt64Bits(double value)
         {
+            // Workaround for https://github.com/dotnet/runtime/issues/11413
+            if (Sse2.X64.IsSupported)
+            {
+                Vector128<long> vec = Vector128.CreateScalarUnsafe(value).AsInt64();
+                return Sse2.X64.ConvertToInt64(vec);
+            }
+
             return *((long*)&value);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static unsafe double Int64BitsToDouble(long value)
         {
+            // Workaround for https://github.com/dotnet/runtime/issues/11413
+            if (Sse2.X64.IsSupported)
+            {
+                Vector128<double> vec = Vector128.CreateScalarUnsafe(value).AsDouble();
+                return vec.ToScalar();
+            }
+
             return *((double*)&value);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static unsafe int SingleToInt32Bits(float value)
         {
+            // Workaround for https://github.com/dotnet/runtime/issues/11413
+            if (Sse2.IsSupported)
+            {
+                Vector128<int> vec = Vector128.CreateScalarUnsafe(value).AsInt32();
+                return Sse2.ConvertToInt32(vec);
+            }
+
             return *((int*)&value);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static unsafe float Int32BitsToSingle(int value)
         {
+            // Workaround for https://github.com/dotnet/runtime/issues/11413
+            if (Sse2.IsSupported)
+            {
+                Vector128<float> vec = Vector128.CreateScalarUnsafe(value).AsSingle();
+                return vec.ToScalar();
+            }
+
             return *((float*)&value);
         }
     }

src/System.Private.CoreLib/shared/System/Boolean.cs

@@ -12,6 +12,7 @@
 **
 ===========================================================*/
 
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Runtime.Versioning;
 
@@ -223,7 +224,7 @@ namespace System
 
         // Determines whether a String represents true or false.
         //
-        public static bool TryParse(string? value, out bool result)
+        public static bool TryParse([NotNullWhen(true)] string? value, out bool result)
         {
             if (value == null)
             {

src/System.Private.CoreLib/shared/System/Buffers/Text/Utf8Parser/ParserHelpers.cs

@@ -2,7 +2,10 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
+using Internal.Runtime.CompilerServices;
 
 namespace System.Buffers.Text
 {
@@ -70,5 +73,23 @@ namespace System.Buffers.Text
             value = default;
             return TryParseThrowFormatException(out bytesConsumed);
         }
+
+        //
+        // Enable use of ThrowHelper from TryParse() routines without introducing dozens of non-code-coveraged "value= default; bytesConsumed = 0; return false" boilerplate.
+        //
+        [DoesNotReturn]
+        [StackTraceHidden]
+        public static bool TryParseThrowFormatException<T>(ReadOnlySpan<byte> source, out T value, out int bytesConsumed) where T : struct
+        {
+            // The parameters to this method are ordered the same as our callers' parameters
+            // allowing the JIT to avoid unnecessary register swapping or spilling.
+
+            Unsafe.SkipInit(out value); // bypass language initialization rules since we're about to throw
+            Unsafe.SkipInit(out bytesConsumed);
+            ThrowHelper.ThrowFormatException_BadFormatSpecifier();
+
+            Debug.Fail("Control should never reach this point.");
+            return false;
+        }
     }
 }

src/System.Private.CoreLib/shared/System/Buffers/Text/Utf8Parser/Utf8Parser.Boolean.cs

@@ -30,7 +30,7 @@ namespace System.Buffers.Text
         public static bool TryParse(ReadOnlySpan<byte> source, out bool value, out int bytesConsumed, char standardFormat = default)
         {
             if (!(standardFormat == default(char) || standardFormat == 'G' || standardFormat == 'l'))
-                return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
+                ThrowHelper.ThrowFormatException_BadFormatSpecifier();
 
             if (source.Length >= 4)
             {
@@ -42,7 +42,7 @@ namespace System.Buffers.Text
                     return true;
                 }
 
-                if (source.Length >= 5)
+                if (4 < (uint)source.Length)
                 {
                     if (dw == 0x534c4146 /* 'SLAF' */ && (source[4] & ~0x20) == 'E')
                     {

src/System.Private.CoreLib/shared/System/Buffers/Text/Utf8Parser/Utf8Parser.Guid.cs

@@ -29,19 +29,25 @@ namespace System.Buffers.Text
         /// </exceptions>
         public static bool TryParse(ReadOnlySpan<byte> source, out Guid value, out int bytesConsumed, char standardFormat = default)
         {
+        FastPath:
+            if (standardFormat == default)
+            {
+                return TryParseGuidCore(source, out value, out bytesConsumed, ends: 0);
+            }
+
             switch (standardFormat)
             {
-                case default(char):
                 case 'D':
-                    return TryParseGuidCore(source, false, ' ', ' ', out value, out bytesConsumed);
+                    standardFormat = default;
+                    goto FastPath;
                 case 'B':
-                    return TryParseGuidCore(source, true, '{', '}', out value, out bytesConsumed);
+                    return TryParseGuidCore(source, out value, out bytesConsumed, ends: '{' | ('}' << 8));
                 case 'P':
-                    return TryParseGuidCore(source, true, '(', ')', out value, out bytesConsumed);
+                    return TryParseGuidCore(source, out value, out bytesConsumed, ends: '(' | (')' << 8));
                 case 'N':
                     return TryParseGuidN(source, out value, out bytesConsumed);
                 default:
-                    return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
+                    return ParserHelpers.TryParseThrowFormatException(source, out value, out bytesConsumed);
             }
         }
 
@@ -97,9 +103,9 @@ namespace System.Buffers.Text
         }
 
         // {8-4-4-4-12}, where number is the number of hex digits, and {/} are ends.
-        private static bool TryParseGuidCore(ReadOnlySpan<byte> source, bool ends, char begin, char end, out Guid value, out int bytesConsumed)
+        private static bool TryParseGuidCore(ReadOnlySpan<byte> source, out Guid value, out int bytesConsumed, int ends)
         {
-            int expectedCodingUnits = 36 + (ends ? 2 : 0); // 32 hex digits + 4 delimiters + 2 optional ends
+            int expectedCodingUnits = 36 + ((ends != 0) ? 2 : 0); // 32 hex digits + 4 delimiters + 2 optional ends
 
             if (source.Length < expectedCodingUnits)
             {
@@ -108,9 +114,16 @@ namespace System.Buffers.Text
                 return false;
             }
 
-            if (ends)
+            // The 'ends' parameter is a 16-bit value where the byte denoting the starting
+            // brace is at byte position 0 and the byte denoting the closing brace is at
+            // byte position 1. If no braces are expected, has value 0.
+            // Default: ends = 0
+            //  Braces: ends = "}{"
+            //  Parens: ends = ")("
+
+            if (ends != 0)
             {
-                if (source[0] != begin)
+                if (source[0] != (byte)ends)
                 {
                     value = default;
                     bytesConsumed = 0;
@@ -118,6 +131,7 @@ namespace System.Buffers.Text
                 }
 
                 source = source.Slice(1); // skip beginning
+                ends >>= 8; // shift the closing brace to byte position 0
             }
 
             if (!TryParseUInt32X(source, out uint i1, out int justConsumed))
@@ -226,7 +240,7 @@ namespace System.Buffers.Text
                 return false; // 12 digits
             }
 
-            if (ends && source[justConsumed] != end)
+            if (ends != 0 && source[justConsumed] != (byte)ends)
             {
                 value = default;
                 bytesConsumed = 0;

src/System.Private.CoreLib/shared/System/Buffers/Text/Utf8Parser/Utf8Parser.Integer.Signed.cs

@@ -35,26 +35,31 @@ namespace System.Buffers.Text
         [CLSCompliant(false)]
         public static bool TryParse(ReadOnlySpan<byte> source, out sbyte value, out int bytesConsumed, char standardFormat = default)
         {
-            switch (standardFormat)
+        FastPath:
+            if (standardFormat == default)
+            {
+                return TryParseSByteD(source, out value, out bytesConsumed);
+            }
+
+            // There's small but measurable overhead when entering the switch block below.
+            // We optimize for the default case by hoisting it above the switch block.
+
+            switch (standardFormat | 0x20) // convert to lowercase
             {
-                case default(char):
                 case 'g':
-                case 'G':
                 case 'd':
-                case 'D':
-                    return TryParseSByteD(source, out value, out bytesConsumed);
+                    standardFormat = default;
+                    goto FastPath;
 
                 case 'n':
-                case 'N':
                     return TryParseSByteN(source, out value, out bytesConsumed);
 
                 case 'x':
-                case 'X':
-                    value = default;
+                    Unsafe.SkipInit(out value); // will be populated by TryParseByteX
                     return TryParseByteX(source, out Unsafe.As<sbyte, byte>(ref value), out bytesConsumed);
 
                 default:
-                    return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
+                    return ParserHelpers.TryParseThrowFormatException(source, out value, out bytesConsumed);
             }
         }
 
@@ -81,26 +86,31 @@ namespace System.Buffers.Text
         /// </exceptions>
         public static bool TryParse(ReadOnlySpan<byte> source, out short value, out int bytesConsumed, char standardFormat = default)
         {
-            switch (standardFormat)
+        FastPath:
+            if (standardFormat == default)
+            {
+                return TryParseInt16D(source, out value, out bytesConsumed);
+            }
+
+            // There's small but measurable overhead when entering the switch block below.
+            // We optimize for the default case by hoisting it above the switch block.
+
+            switch (standardFormat | 0x20) // convert to lowercase
             {
-                case default(char):
                 case 'g':
-                case 'G':
                 case 'd':
-                case 'D':
-                    return TryParseInt16D(source, out value, out bytesConsumed);
+                    standardFormat = default;
+                    goto FastPath;
 
                 case 'n':
-                case 'N':
                     return TryParseInt16N(source, out value, out bytesConsumed);
 
                 case 'x':
-                case 'X':
-                    value = default;
+                    Unsafe.SkipInit(out value); // will be populated by TryParseUInt16X
                     return TryParseUInt16X(source, out Unsafe.As<short, ushort>(ref value), out bytesConsumed);
 
                 default:
-                    return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
+                    return ParserHelpers.TryParseThrowFormatException(source, out value, out bytesConsumed);
             }
         }
 
@@ -127,26 +137,31 @@ namespace System.Buffers.Text
         /// </exceptions>
         public static bool TryParse(ReadOnlySpan<byte> source, out int value, out int bytesConsumed, char standardFormat = default)
         {
-            switch (standardFormat)
+        FastPath:
+            if (standardFormat == default)
+            {
+                return TryParseInt32D(source, out value, out bytesConsumed);
+            }
+
+            // There's small but measurable overhead when entering the switch block below.
+            // We optimize for the default case by hoisting it above the switch block.
+
+            switch (standardFormat | 0x20) // convert to lowercase
             {
-                case default(char):
                 case 'g':
-                case 'G':
                 case 'd':
-                case 'D':
-                    return TryParseInt32D(source, out value, out bytesConsumed);
+                    standardFormat = default;
+                    goto FastPath;
 
                 case 'n':
-                case 'N':
                     return TryParseInt32N(source, out value, out bytesConsumed);
 
                 case 'x':
-                case 'X':
-                    value = default;
+                    Unsafe.SkipInit(out value); // will be populated by TryParseUInt32X
                     return TryParseUInt32X(source, out Unsafe.As<int, uint>(ref value), out bytesConsumed);
 
                 default:
-                    return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
+                    return ParserHelpers.TryParseThrowFormatException(source, out value, out bytesConsumed);
             }
         }
 
@@ -173,26 +188,31 @@ namespace System.Buffers.Text
         /// </exceptions>
         public static bool TryParse(ReadOnlySpan<byte> source, out long value, out int bytesConsumed, char standardFormat = default)
         {
-            switch (standardFormat)
+        FastPath:
+            if (standardFormat == default)
+            {
+                return TryParseInt64D(source, out value, out bytesConsumed);
+            }
+
+            // There's small but measurable overhead when entering the switch block below.
+            // We optimize for the default case by hoisting it above the switch block.
+
+            switch (standardFormat | 0x20) // convert to lowercase
             {
-                case default(char):
                 case 'g':
-                case 'G':
                 case 'd':
-                case 'D':
-                    return TryParseInt64D(source, out value, out bytesConsumed);
+                    standardFormat = default;
+                    goto FastPath;
 
                 case 'n':
-                case 'N':
                     return TryParseInt64N(source, out value, out bytesConsumed);
 
                 case 'x':
-                case 'X':
-                    value = default;
+                    Unsafe.SkipInit(out value); // will be populated by TryParseUInt64X
                     return TryParseUInt64X(source, out Unsafe.As<long, ulong>(ref value), out bytesConsumed);
 
                 default:
-                    return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
+                    return ParserHelpers.TryParseThrowFormatException(source, out value, out bytesConsumed);
             }
         }
     }

src/System.Private.CoreLib/shared/System/Buffers/Text/Utf8Parser/Utf8Parser.Integer.Unsigned.cs

@@ -29,25 +29,30 @@ namespace System.Buffers.Text
         /// </exceptions>
         public static bool TryParse(ReadOnlySpan<byte> source, out byte value, out int bytesConsumed, char standardFormat = default)
         {
-            switch (standardFormat)
+        FastPath:
+            if (standardFormat == default)
+            {
+                return TryParseByteD(source, out value, out bytesConsumed);
+            }
+
+            // There's small but measurable overhead when entering the switch block below.
+            // We optimize for the default case by hoisting it above the switch block.
+
+            switch (standardFormat | 0x20) // convert to lowercase
             {
-                case default(char):
                 case 'g':
-                case 'G':
                 case 'd':
-                case 'D':
-                    return TryParseByteD(source, out value, out bytesConsumed);
+                    standardFormat = default;
+                    goto FastPath;
 
                 case 'n':
-                case 'N':
                     return TryParseByteN(source, out value, out bytesConsumed);
 
                 case 'x':
-                case 'X':
                     return TryParseByteX(source, out value, out bytesConsumed);
 
                 default:
-                    return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
+                    return ParserHelpers.TryParseThrowFormatException(source, out value, out bytesConsumed);
             }
         }
 
@@ -75,25 +80,30 @@ namespace System.Buffers.Text
         [CLSCompliant(false)]
         public static bool TryParse(ReadOnlySpan<byte> source, out ushort value, out int bytesConsumed, char standardFormat = default)
         {
-            switch (standardFormat)
+        FastPath:
+            if (standardFormat == default)
+            {
+                return TryParseUInt16D(source, out value, out bytesConsumed);
+            }
+
+            // There's small but measurable overhead when entering the switch block below.
+            // We optimize for the default case by hoisting it above the switch block.
+
+            switch (standardFormat | 0x20) // convert to lowercase
             {
-                case default(char):
                 case 'g':
-                case 'G':
                 case 'd':
-                case 'D':
-                    return TryParseUInt16D(source, out value, out bytesConsumed);
+                    standardFormat = default;
+                    goto FastPath;
 
                 case 'n':
-                case 'N':
                     return TryParseUInt16N(source, out value, out bytesConsumed);
 
                 case 'x':
-                case 'X':
                     return TryParseUInt16X(source, out value, out bytesConsumed);
 
                 default:
-                    return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
+                    return ParserHelpers.TryParseThrowFormatException(source, out value, out bytesConsumed);
             }
         }
 
@@ -121,25 +131,30 @@ namespace System.Buffers.Text
         [CLSCompliant(false)]
         public static bool TryParse(ReadOnlySpan<byte> source, out uint value, out int bytesConsumed, char standardFormat = default)
         {
-            switch (standardFormat)
+        FastPath:
+            if (standardFormat == default)
+            {
+                return TryParseUInt32D(source, out value, out bytesConsumed);
+            }
+
+            // There's small but measurable overhead when entering the switch block below.
+            // We optimize for the default case by hoisting it above the switch block.
+
+            switch (standardFormat | 0x20) // convert to lowercase
             {
-                case default(char):
                 case 'g':
-                case 'G':
                 case 'd':
-                case 'D':
-                    return TryParseUInt32D(source, out value, out bytesConsumed);
+                    standardFormat = default;
+                    goto FastPath;
 
                 case 'n':
-                case 'N':
                     return TryParseUInt32N(source, out value, out bytesConsumed);
 
                 case 'x':
-                case 'X':
                     return TryParseUInt32X(source, out value, out bytesConsumed);
 
                 default:
-                    return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
+                    return ParserHelpers.TryParseThrowFormatException(source, out value, out bytesConsumed);
             }
         }
 
@@ -167,25 +182,30 @@ namespace System.Buffers.Text
         [CLSCompliant(false)]
         public static bool TryParse(ReadOnlySpan<byte> source, out ulong value, out int bytesConsumed, char standardFormat = default)
         {
-            switch (standardFormat)
+        FastPath:
+            if (standardFormat == default)
+            {
+                return TryParseUInt64D(source, out value, out bytesConsumed);
+            }
+
+            // There's small but measurable overhead when entering the switch block below.
+            // We optimize for the default case by hoisting it above the switch block.
+
+            switch (standardFormat | 0x20) // convert to lowercase
             {
-                case default(char):
                 case 'g':
-                case 'G':
                 case 'd':
-                case 'D':
-                    return TryParseUInt64D(source, out value, out bytesConsumed);
+                    standardFormat = default;
+                    goto FastPath;
 
                 case 'n':
-                case 'N':
                     return TryParseUInt64N(source, out value, out bytesConsumed);
 
                 case 'x':
-                case 'X':
                     return TryParseUInt64X(source, out value, out bytesConsumed);
 
                 default:
-                    return ParserHelpers.TryParseThrowFormatException(out value, out bytesConsumed);
+                    return ParserHelpers.TryParseThrowFormatException(source, out value, out bytesConsumed);
             }
         }
     }

src/System.Private.CoreLib/shared/System/Byte.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -117,7 +118,7 @@ namespace System
             return (byte)i;
         }
 
-        public static bool TryParse(string? s, out byte result)
+        public static bool TryParse([NotNullWhen(true)] string? s, out byte result)
         {
             if (s == null)
             {
@@ -133,7 +134,7 @@ namespace System
             return TryParse(s, NumberStyles.Integer, NumberFormatInfo.CurrentInfo, out result);
         }
 
-        public static bool TryParse(string? s, NumberStyles style, IFormatProvider? provider, out byte result)
+        public static bool TryParse([NotNullWhen(true)] string? s, NumberStyles style, IFormatProvider? provider, out byte result)
         {
             NumberFormatInfo.ValidateParseStyleInteger(style);
 
@@ -166,7 +167,7 @@ namespace System
 
         public override string ToString()
         {
-            return Number.UInt32ToDecStr(m_value, -1);
+            return Number.UInt32ToDecStr(m_value);
         }
 
         public string ToString(string? format)
@@ -176,7 +177,7 @@ namespace System
 
         public string ToString(IFormatProvider? provider)
         {
-            return Number.FormatUInt32(m_value, null, provider);
+            return Number.UInt32ToDecStr(m_value);
         }
 
         public string ToString(string? format, IFormatProvider? provider)

src/System.Private.CoreLib/shared/System/Char.cs

@@ -13,6 +13,7 @@
 ===========================================================*/
 
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Runtime.InteropServices;
 using System.Text;
@@ -182,7 +183,7 @@ namespace System
             return s[0];
         }
 
-        public static bool TryParse(string? s, out char result)
+        public static bool TryParse([NotNullWhen(true)] string? s, out char result)
         {
             result = '\0';
             if (s == null)
@@ -353,10 +354,7 @@ namespace System
         }
 
         // Converts a character to upper-case for invariant culture.
-        public static char ToUpperInvariant(char c)
-        {
-            return TextInfo.Invariant.ToUpper(c);
-        }
+        public static char ToUpperInvariant(char c) => TextInfo.ToUpperInvariant(c);
 
         /*===================================ToLower====================================
         **
@@ -382,10 +380,7 @@ namespace System
         }
 
         // Converts a character to lower-case for invariant culture.
-        public static char ToLowerInvariant(char c)
-        {
-            return TextInfo.Invariant.ToLower(c);
-        }
+        public static char ToLowerInvariant(char c) => TextInfo.ToLowerInvariant(c);
 
         //
         // IConvertible implementation

src/System.Private.CoreLib/shared/System/Collections/Concurrent/ConcurrentQueue.cs

@@ -222,9 +222,7 @@ namespace System.Collections.Concurrent
         public T[] ToArray()
         {
             // Snap the current contents for enumeration.
-            ConcurrentQueueSegment<T> head, tail;
-            int headHead, tailTail;
-            SnapForObservation(out head, out headHead, out tail, out tailTail);
+            SnapForObservation(out ConcurrentQueueSegment<T> head, out int headHead, out ConcurrentQueueSegment<T> tail, out int tailTail);
 
             // Count the number of items in that snapped set, and use it to allocate an
             // array of the right size.
@@ -450,9 +448,7 @@ namespace System.Collections.Concurrent
             }
 
             // Snap for enumeration
-            ConcurrentQueueSegment<T> head, tail;
-            int headHead, tailTail;
-            SnapForObservation(out head, out headHead, out tail, out tailTail);
+            SnapForObservation(out ConcurrentQueueSegment<T> head, out int headHead, out ConcurrentQueueSegment<T> tail, out int tailTail);
 
             // Get the number of items to be enumerated
             long count = GetCount(head, headHead, tail, tailTail);
@@ -484,9 +480,7 @@ namespace System.Collections.Concurrent
         /// </remarks>
         public IEnumerator<T> GetEnumerator()
         {
-            ConcurrentQueueSegment<T> head, tail;
-            int headHead, tailTail;
-            SnapForObservation(out head, out headHead, out tail, out tailTail);
+            SnapForObservation(out ConcurrentQueueSegment<T> head, out int headHead, out ConcurrentQueueSegment<T> tail, out int tailTail);
             return Enumerate(head, headHead, tail, tailTail);
         }
 

src/System.Private.CoreLib/shared/System/Collections/Generic/ArraySortHelper.cs

@@ -2,50 +2,23 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-/*============================================================
-**
-**
-**
-**
-**
-** Purpose: class to sort arrays
-**
-**
-===========================================================*/
-
 using System.Diagnostics;
-using System.Diagnostics.CodeAnalysis;
+using System.Numerics;
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using Internal.Runtime.CompilerServices;
+
+#pragma warning disable SA1121 // explicitly using type aliases instead of built-in types
+#if TARGET_64BIT
+using nint = System.Int64;
+#else
+using nint = System.Int32;
+#endif
 
 namespace System.Collections.Generic
 {
     #region ArraySortHelper for single arrays
 
-    internal static class IntrospectiveSortUtilities
-    {
-        // This is the threshold where Introspective sort switches to Insertion sort.
-        // Empirically, 16 seems to speed up most cases without slowing down others, at least for integers.
-        // Large value types may benefit from a smaller number.
-        internal const int IntrosortSizeThreshold = 16;
-
-        internal static int FloorLog2PlusOne(int n)
-        {
-            int result = 0;
-            while (n >= 1)
-            {
-                result++;
-                n /= 2;
-            }
-            return result;
-        }
-
-        [DoesNotReturn]
-        internal static void ThrowOrIgnoreBadComparer(object? comparer)
-        {
-            throw new ArgumentException(SR.Format(SR.Arg_BogusIComparer, comparer));
-        }
-    }
-
     internal partial class ArraySortHelper<T>
     {
         #region IArraySortHelper<T> Members
@@ -61,11 +34,11 @@ namespace System.Collections.Generic
             }
             catch (IndexOutOfRangeException)
             {
-                IntrospectiveSortUtilities.ThrowOrIgnoreBadComparer(comparer);
+                ThrowHelper.ThrowArgumentException_BadComparer(comparer);
             }
             catch (Exception e)
             {
-                throw new InvalidOperationException(SR.InvalidOperation_IComparerFailed, e);
+                ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_IComparerFailed, e);
             }
         }
 
@@ -78,7 +51,8 @@ namespace System.Collections.Generic
             }
             catch (Exception e)
             {
-                throw new InvalidOperationException(SR.InvalidOperation_IComparerFailed, e);
+                ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_IComparerFailed, e);
+                return 0;
             }
         }
 
@@ -95,11 +69,11 @@ namespace System.Collections.Generic
             }
             catch (IndexOutOfRangeException)
             {
-                IntrospectiveSortUtilities.ThrowOrIgnoreBadComparer(comparer);
+                ThrowHelper.ThrowArgumentException_BadComparer(comparer);
             }
             catch (Exception e)
             {
-                throw new InvalidOperationException(SR.InvalidOperation_IComparerFailed, e);
+                ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_IComparerFailed, e);
             }
         }
 
@@ -131,26 +105,24 @@ namespace System.Collections.Generic
 
         private static void SwapIfGreater(Span<T> keys, Comparison<T> comparer, int i, int j)
         {
-            if (i != j)
+            Debug.Assert(i != j);
+
+            if (comparer(keys[i], keys[j]) > 0)
             {
-                if (comparer(keys[i], keys[j]) > 0)
-                {
-                    T key = keys[i];
-                    keys[i] = keys[j];
-                    keys[j] = key;
-                }
+                T key = keys[i];
+                keys[i] = keys[j];
+                keys[j] = key;
             }
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static void Swap(Span<T> a, int i, int j)
         {
-            if (i != j)
-            {
-                T t = a[i];
-                a[i] = a[j];
-                a[j] = t;
-            }
+            Debug.Assert(i != j);
+
+            T t = a[i];
+            a[i] = a[j];
+            a[j] = t;
         }
 
         internal static void IntrospectiveSort(Span<T> keys, Comparison<T> comparer)
@@ -159,53 +131,51 @@ namespace System.Collections.Generic
 
             if (keys.Length > 1)
             {
-                IntroSort(keys, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(keys.Length), comparer);
+                IntroSort(keys, 2 * (BitOperations.Log2((uint)keys.Length) + 1), comparer);
             }
         }
 
         private static void IntroSort(Span<T> keys, int depthLimit, Comparison<T> comparer)
         {
-            int lo = 0;
-            int hi = keys.Length - 1;
-
+            Debug.Assert(!keys.IsEmpty);
+            Debug.Assert(depthLimit >= 0);
             Debug.Assert(comparer != null);
 
-            while (hi > lo)
+            int hi = keys.Length - 1;
+            while (hi > 0)
             {
-                int partitionSize = hi - lo + 1;
-                if (partitionSize <= IntrospectiveSortUtilities.IntrosortSizeThreshold)
+                int partitionSize = hi + 1;
+
+                if (partitionSize <= Array.IntrosortSizeThreshold)
                 {
-                    if (partitionSize == 1)
-                    {
-                        return;
-                    }
+                    Debug.Assert(partitionSize >= 2);
 
                     if (partitionSize == 2)
                     {
-                        SwapIfGreater(keys, comparer, lo, hi);
+                        SwapIfGreater(keys, comparer, 0, hi);
                         return;
                     }
 
                     if (partitionSize == 3)
                     {
-                        SwapIfGreater(keys, comparer, lo, hi - 1);
-                        SwapIfGreater(keys, comparer, lo, hi);
+                        SwapIfGreater(keys, comparer, 0, hi - 1);
+                        SwapIfGreater(keys, comparer, 0, hi);
                         SwapIfGreater(keys, comparer, hi - 1, hi);
                         return;
                     }
 
-                    InsertionSort(keys[lo..(hi+1)], comparer);
+                    InsertionSort(keys.Slice(0, hi+1), comparer);
                     return;
                 }
 
                 if (depthLimit == 0)
                 {
-                    HeapSort(keys[lo..(hi+1)], comparer);
+                    HeapSort(keys.Slice(0, hi+1), comparer);
                     return;
                 }
                 depthLimit--;
 
-                int p = PickPivotAndPartition(keys[lo..(hi+1)], comparer);
+                int p = PickPivotAndPartition(keys.Slice(0, hi+1), comparer);
 
                 // Note we've already partitioned around the pivot and do not have to move the pivot again.
                 IntroSort(keys[(p+1)..(hi+1)], depthLimit, comparer);
@@ -215,23 +185,22 @@ namespace System.Collections.Generic
 
         private static int PickPivotAndPartition(Span<T> keys, Comparison<T> comparer)
         {
+            Debug.Assert(keys.Length >= Array.IntrosortSizeThreshold);
             Debug.Assert(comparer != null);
-            Debug.Assert(!keys.IsEmpty);
 
-            int lo = 0;
             int hi = keys.Length - 1;
 
             // Compute median-of-three.  But also partition them, since we've done the comparison.
-            int middle = lo + ((hi - lo) / 2);
+            int middle = hi >> 1;
 
             // Sort lo, mid and hi appropriately, then pick mid as the pivot.
-            SwapIfGreater(keys, comparer, lo, middle);  // swap the low with the mid point
-            SwapIfGreater(keys, comparer, lo, hi);   // swap the low with the high
+            SwapIfGreater(keys, comparer, 0, middle);  // swap the low with the mid point
+            SwapIfGreater(keys, comparer, 0, hi);   // swap the low with the high
             SwapIfGreater(keys, comparer, middle, hi); // swap the middle with the high
 
             T pivot = keys[middle];
             Swap(keys, middle, hi - 1);
-            int left = lo, right = hi - 1;  // We already partitioned lo and hi and put the pivot in hi - 1.  And we pre-increment & decrement below.
+            int left = 0, right = hi - 1;  // We already partitioned lo and hi and put the pivot in hi - 1.  And we pre-increment & decrement below.
 
             while (left < right)
             {
@@ -245,7 +214,10 @@ namespace System.Collections.Generic
             }
 
             // Put pivot in the right location.
-            Swap(keys, left, hi - 1);
+            if (left != hi - 1)
+            {
+                Swap(keys, left, hi - 1);
+            }
             return left;
         }
 
@@ -254,20 +226,16 @@ namespace System.Collections.Generic
             Debug.Assert(comparer != null);
             Debug.Assert(!keys.IsEmpty);
 
-            int lo = 0;
-            int hi = keys.Length - 1;
-
-            int n = hi - lo + 1;
-
-            for (int i = n / 2; i >= 1; i--)
+            int n = keys.Length;
+            for (int i = n >> 1; i >= 1; i--)
             {
-                DownHeap(keys, i, n, lo, comparer);
+                DownHeap(keys, i, n, 0, comparer);
             }
 
             for (int i = n; i > 1; i--)
             {
-                Swap(keys, lo, lo + i - 1);
-                DownHeap(keys, 1, i - 1, lo, comparer);
+                Swap(keys, 0, i - 1);
+                DownHeap(keys, 1, i - 1, 0, comparer);
             }
         }
 
@@ -278,7 +246,7 @@ namespace System.Collections.Generic
             Debug.Assert(lo < keys.Length);
 
             T d = keys[lo + i - 1];
-            while (i <= n / 2)
+            while (i <= n >> 1)
             {
                 int child = 2 * i;
                 if (child < n && comparer(keys[lo + child - 1], keys[lo + child]) < 0)
@@ -327,7 +295,10 @@ namespace System.Collections.Generic
             {
                 if (comparer == null || comparer == Comparer<T>.Default)
                 {
-                    IntrospectiveSort(keys);
+                    if (keys.Length > 1)
+                    {
+                        IntroSort(keys, 2 * (BitOperations.Log2((uint)keys.Length) + 1));
+                    }
                 }
                 else
                 {
@@ -336,11 +307,11 @@ namespace System.Collections.Generic
             }
             catch (IndexOutOfRangeException)
             {
-                IntrospectiveSortUtilities.ThrowOrIgnoreBadComparer(comparer);
+                ThrowHelper.ThrowArgumentException_BadComparer(comparer);
             }
             catch (Exception e)
             {
-                throw new InvalidOperationException(SR.InvalidOperation_IComparerFailed, e);
+                ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_IComparerFailed, e);
             }
         }
 
@@ -362,7 +333,8 @@ namespace System.Collections.Generic
             }
             catch (Exception e)
             {
-                throw new InvalidOperationException(SR.InvalidOperation_IComparerFailed, e);
+                ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_IComparerFailed, e);
+                return 0;
             }
         }
 
@@ -406,147 +378,140 @@ namespace System.Collections.Generic
             return ~lo;
         }
 
-        private static void SwapIfGreater(Span<T> keys, int i, int j)
-        {
-            Debug.Assert(0 <= i && i < keys.Length);
-            Debug.Assert(0 <= j && j < keys.Length);
-
-            if (i != j)
-            {
-                if (keys[i] != null && keys[i].CompareTo(keys[j]) > 0)
-                {
-                    T key = keys[i];
-                    keys[i] = keys[j];
-                    keys[j] = key;
-                }
-            }
-        }
-
+        /// <summary>Swaps the values in the two references if the first is greater than the second.</summary>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static void Swap(Span<T> a, int i, int j)
+        private static void SwapIfGreater(ref T i, ref T j)
         {
-            if (i != j)
+            if (i != null && i.CompareTo(j) > 0)
             {
-                T t = a[i];
-                a[i] = a[j];
-                a[j] = t;
+                Swap(ref i, ref j);
             }
         }
 
-        internal static void IntrospectiveSort(Span<T> keys)
+        /// <summary>Swaps the values in the two references, regardless of whether the two references are the same.</summary>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void Swap(ref T i, ref T j)
         {
-            if (keys.Length > 1)
-            {
-                IntroSort(keys, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(keys.Length));
-            }
+            Debug.Assert(!Unsafe.AreSame(ref i, ref j));
+
+            T t = i;
+            i = j;
+            j = t;
         }
 
         private static void IntroSort(Span<T> keys, int depthLimit)
         {
-            int lo = 0;
-            int hi = keys.Length - 1;
+            Debug.Assert(!keys.IsEmpty);
+            Debug.Assert(depthLimit >= 0);
 
-            while (hi > lo)
+            int hi = keys.Length - 1;
+            while (hi > 0)
             {
-                int partitionSize = hi - lo + 1;
-                if (partitionSize <= IntrospectiveSortUtilities.IntrosortSizeThreshold)
+                int partitionSize = hi + 1;
+
+                if (partitionSize <= Array.IntrosortSizeThreshold)
                 {
-                    if (partitionSize == 1)
-                    {
-                        return;
-                    }
+                    Debug.Assert(partitionSize >= 2);
+
                     if (partitionSize == 2)
                     {
-                        SwapIfGreater(keys, lo, hi);
-                        return;
-                    }
-                    if (partitionSize == 3)
-                    {
-                        SwapIfGreater(keys, lo, hi - 1);
-                        SwapIfGreater(keys, lo, hi);
-                        SwapIfGreater(keys, hi - 1, hi);
+                        SwapIfGreater(ref keys[0], ref keys[1]);
                         return;
                     }
 
-                    InsertionSort(keys[lo..(hi+1)]);
+                    if (partitionSize == 3)
+                    {
+                        ref T hiRef = ref keys[2];
+                        ref T him1Ref = ref keys[1];
+                        ref T loRef = ref keys[0];
+
+                        SwapIfGreater(ref loRef, ref him1Ref);
+                        SwapIfGreater(ref loRef, ref hiRef);
+                        SwapIfGreater(ref him1Ref, ref hiRef);
+                        return;
+                    }
+
+                    InsertionSort(keys.Slice(0, partitionSize));
                     return;
                 }
 
                 if (depthLimit == 0)
                 {
-                    HeapSort(keys[lo..(hi+1)]);
+                    HeapSort(keys.Slice(0, partitionSize));
                     return;
                 }
                 depthLimit--;
 
-                int p = PickPivotAndPartition(keys[lo..(hi+1)]);
+                int p = PickPivotAndPartition(keys.Slice(0, partitionSize));
 
                 // Note we've already partitioned around the pivot and do not have to move the pivot again.
-                IntroSort(keys[(p+1)..(hi+1)], depthLimit);
+                IntroSort(keys[(p+1)..partitionSize], depthLimit);
                 hi = p - 1;
             }
         }
 
         private static int PickPivotAndPartition(Span<T> keys)
         {
-            Debug.Assert(!keys.IsEmpty);
+            Debug.Assert(keys.Length >= Array.IntrosortSizeThreshold);
 
-            int lo = 0;
-            int hi = keys.Length - 1;
+            // Use median-of-three to select a pivot. Grab a reference to the 0th, Length-1th, and Length/2th elements, and sort them.
+            ref T zeroRef = ref MemoryMarshal.GetReference(keys);
+            ref T lastRef = ref Unsafe.Add(ref zeroRef, keys.Length - 1);
+            ref T middleRef = ref Unsafe.Add(ref zeroRef, (keys.Length - 1) >> 1);
+            SwapIfGreater(ref zeroRef, ref middleRef);
+            SwapIfGreater(ref zeroRef, ref lastRef);
+            SwapIfGreater(ref middleRef, ref lastRef);
 
-            // Compute median-of-three.  But also partition them, since we've done the comparison.
-            int middle = lo + ((hi - lo) / 2);
+            // Select the middle value as the pivot, and move it to be just before the last element.
+            ref T nextToLastRef = ref Unsafe.Add(ref zeroRef, keys.Length - 2);
+            T pivot = middleRef;
+            Swap(ref middleRef, ref nextToLastRef);
 
-            // Sort lo, mid and hi appropriately, then pick mid as the pivot.
-            SwapIfGreater(keys, lo, middle);  // swap the low with the mid point
-            SwapIfGreater(keys, lo, hi);   // swap the low with the high
-            SwapIfGreater(keys, middle, hi); // swap the middle with the high
-
-            T pivot = keys[middle];
-            Swap(keys, middle, hi - 1);
-            int left = lo, right = hi - 1;  // We already partitioned lo and hi and put the pivot in hi - 1.  And we pre-increment & decrement below.
-
-            while (left < right)
+            // Walk the left and right pointers, swapping elements as necessary, until they cross.
+            ref T leftRef = ref zeroRef, rightRef = ref nextToLastRef;
+            while (Unsafe.IsAddressLessThan(ref leftRef, ref rightRef))
             {
                 if (pivot == null)
                 {
-                    while (left < (hi - 1) && keys[++left] == null) ;
-                    while (right > lo && keys[--right] != null) ;
+                    while (Unsafe.IsAddressLessThan(ref leftRef, ref nextToLastRef) && (leftRef = ref Unsafe.Add(ref leftRef, 1)) == null) ;
+                    while (Unsafe.IsAddressGreaterThan(ref rightRef, ref zeroRef) && (rightRef = ref Unsafe.Add(ref rightRef, -1)) == null) ;
                 }
                 else
                 {
-                    while (pivot.CompareTo(keys[++left]) > 0) ;
-                    while (pivot.CompareTo(keys[--right]) < 0) ;
+                    while (Unsafe.IsAddressLessThan(ref leftRef, ref nextToLastRef) && pivot.CompareTo(leftRef = ref Unsafe.Add(ref leftRef, 1)) > 0) ;
+                    while (Unsafe.IsAddressGreaterThan(ref rightRef, ref zeroRef) && pivot.CompareTo(rightRef = ref Unsafe.Add(ref rightRef, -1)) < 0) ;
                 }
 
-                if (left >= right)
+                if (!Unsafe.IsAddressLessThan(ref leftRef, ref rightRef))
+                {
                     break;
+                }
 
-                Swap(keys, left, right);
+                Swap(ref leftRef, ref rightRef);
             }
 
-            // Put pivot in the right location.
-            Swap(keys, left, hi - 1);
-            return left;
+            // Put the pivot in the correct location.
+            if (!Unsafe.AreSame(ref leftRef, ref nextToLastRef))
+            {
+                Swap(ref leftRef, ref nextToLastRef);
+            }
+            return (int)((nint)Unsafe.ByteOffset(ref zeroRef, ref leftRef) / Unsafe.SizeOf<T>());
         }
 
         private static void HeapSort(Span<T> keys)
         {
             Debug.Assert(!keys.IsEmpty);
 
-            int lo = 0;
-            int hi = keys.Length - 1;
-
-            int n = hi - lo + 1;
-            for (int i = n / 2; i >= 1; i = i - 1)
+            int n = keys.Length;
+            for (int i = n >> 1; i >= 1; i--)
             {
-                DownHeap(keys, i, n, lo);
+                DownHeap(keys, i, n, 0);
             }
 
             for (int i = n; i > 1; i--)
             {
-                Swap(keys, lo, lo + i - 1);
-                DownHeap(keys, 1, i - 1, lo);
+                Swap(ref keys[0], ref keys[i - 1]);
+                DownHeap(keys, 1, i - 1, 0);
             }
         }
 
@@ -556,7 +521,7 @@ namespace System.Collections.Generic
             Debug.Assert(lo < keys.Length);
 
             T d = keys[lo + i - 1];
-            while (i <= n / 2)
+            while (i <= n >> 1)
             {
                 int child = 2 * i;
                 if (child < n && (keys[lo + child - 1] == null || keys[lo + child - 1].CompareTo(keys[lo + child]) < 0))
@@ -578,16 +543,16 @@ namespace System.Collections.Generic
         {
             for (int i = 0; i < keys.Length - 1; i++)
             {
-                T t = keys[i + 1];
+                T t = Unsafe.Add(ref MemoryMarshal.GetReference(keys), i + 1);
 
                 int j = i;
-                while (j >= 0 && (t == null || t.CompareTo(keys[j]) < 0))
+                while (j >= 0 && (t == null || t.CompareTo(Unsafe.Add(ref MemoryMarshal.GetReference(keys), j)) < 0))
                 {
-                    keys[j + 1] = keys[j];
+                    Unsafe.Add(ref MemoryMarshal.GetReference(keys), j + 1) = Unsafe.Add(ref MemoryMarshal.GetReference(keys), j);
                     j--;
                 }
 
-                keys[j + 1] = t;
+                Unsafe.Add(ref MemoryMarshal.GetReference(keys), j + 1) = t;
             }
         }
     }
@@ -608,11 +573,11 @@ namespace System.Collections.Generic
             }
             catch (IndexOutOfRangeException)
             {
-                IntrospectiveSortUtilities.ThrowOrIgnoreBadComparer(comparer);
+                ThrowHelper.ThrowArgumentException_BadComparer(comparer);
             }
             catch (Exception e)
             {
-                throw new InvalidOperationException(SR.InvalidOperation_IComparerFailed, e);
+                ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_IComparerFailed, e);
             }
         }
 
@@ -621,35 +586,32 @@ namespace System.Collections.Generic
             Debug.Assert(comparer != null);
             Debug.Assert(0 <= i && i < keys.Length && i < values.Length);
             Debug.Assert(0 <= j && j < keys.Length && j < values.Length);
+            Debug.Assert(i != j);
 
-            if (i != j)
+            if (comparer.Compare(keys[i], keys[j]) > 0)
             {
-                if (comparer.Compare(keys[i], keys[j]) > 0)
-                {
-                    TKey key = keys[i];
-                    keys[i] = keys[j];
-                    keys[j] = key;
+                TKey key = keys[i];
+                keys[i] = keys[j];
+                keys[j] = key;
 
-                    TValue value = values[i];
-                    values[i] = values[j];
-                    values[j] = value;
-                }
+                TValue value = values[i];
+                values[i] = values[j];
+                values[j] = value;
             }
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static void Swap(Span<TKey> keys, Span<TValue> values, int i, int j)
         {
-            if (i != j)
-            {
-                TKey k = keys[i];
-                keys[i] = keys[j];
-                keys[j] = k;
+            Debug.Assert(i != j);
 
-                TValue v = values[i];
-                values[i] = values[j];
-                values[j] = v;
-            }
+            TKey k = keys[i];
+            keys[i] = keys[j];
+            keys[j] = k;
+
+            TValue v = values[i];
+            values[i] = values[j];
+            values[j] = v;
         }
 
         internal static void IntrospectiveSort(Span<TKey> keys, Span<TValue> values, IComparer<TKey> comparer)
@@ -659,79 +621,77 @@ namespace System.Collections.Generic
 
             if (keys.Length > 1)
             {
-                IntroSort(keys, values, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(keys.Length), comparer);
+                IntroSort(keys, values, 2 * (BitOperations.Log2((uint)keys.Length) + 1), comparer);
             }
         }
 
         private static void IntroSort(Span<TKey> keys, Span<TValue> values, int depthLimit, IComparer<TKey> comparer)
         {
+            Debug.Assert(!keys.IsEmpty);
+            Debug.Assert(values.Length == keys.Length);
+            Debug.Assert(depthLimit >= 0);
             Debug.Assert(comparer != null);
 
-            int lo = 0;
             int hi = keys.Length - 1;
-
-            while (hi > lo)
+            while (hi > 0)
             {
-                int partitionSize = hi - lo + 1;
-                if (partitionSize <= IntrospectiveSortUtilities.IntrosortSizeThreshold)
+                int partitionSize = hi + 1;
+
+                if (partitionSize <= Array.IntrosortSizeThreshold)
                 {
-                    if (partitionSize == 1)
-                    {
-                        return;
-                    }
+                    Debug.Assert(partitionSize >= 2);
 
                     if (partitionSize == 2)
                     {
-                        SwapIfGreaterWithValues(keys, values, comparer, lo, hi);
+                        SwapIfGreaterWithValues(keys, values, comparer, 0, hi);
                         return;
                     }
 
                     if (partitionSize == 3)
                     {
-                        SwapIfGreaterWithValues(keys, values, comparer, lo, hi - 1);
-                        SwapIfGreaterWithValues(keys, values, comparer, lo, hi);
+                        SwapIfGreaterWithValues(keys, values, comparer, 0, hi - 1);
+                        SwapIfGreaterWithValues(keys, values, comparer, 0, hi);
                         SwapIfGreaterWithValues(keys, values, comparer, hi - 1, hi);
                         return;
                     }
 
-                    InsertionSort(keys[lo..(hi+1)], values[lo..(hi+1)], comparer);
+                    InsertionSort(keys.Slice(0, partitionSize), values.Slice(0, partitionSize), comparer);
                     return;
                 }
 
                 if (depthLimit == 0)
                 {
-                    HeapSort(keys[lo..(hi+1)], values[lo..(hi+1)], comparer);
+                    HeapSort(keys.Slice(0, partitionSize), values.Slice(0, partitionSize), comparer);
                     return;
                 }
                 depthLimit--;
 
-                int p = PickPivotAndPartition(keys[lo..(hi+1)], values[lo..(hi+1)], comparer);
+                int p = PickPivotAndPartition(keys.Slice(0, partitionSize), values.Slice(0, partitionSize), comparer);
 
                 // Note we've already partitioned around the pivot and do not have to move the pivot again.
-                IntroSort(keys[(p+1)..(hi+1)], values[(p+1)..(hi+1)], depthLimit, comparer);
+                IntroSort(keys[(p+1)..partitionSize], values[(p+1)..partitionSize], depthLimit, comparer);
                 hi = p - 1;
             }
         }
 
         private static int PickPivotAndPartition(Span<TKey> keys, Span<TValue> values, IComparer<TKey> comparer)
         {
+            Debug.Assert(keys.Length >= Array.IntrosortSizeThreshold);
             Debug.Assert(comparer != null);
-            Debug.Assert(!keys.IsEmpty);
 
-            int lo = 0;
             int hi = keys.Length - 1;
 
             // Compute median-of-three.  But also partition them, since we've done the comparison.
-            int middle = lo + ((hi - lo) / 2);
+            int middle = hi >> 1;
 
             // Sort lo, mid and hi appropriately, then pick mid as the pivot.
-            SwapIfGreaterWithValues(keys, values, comparer, lo, middle);  // swap the low with the mid point
-            SwapIfGreaterWithValues(keys, values, comparer, lo, hi);   // swap the low with the high
+            SwapIfGreaterWithValues(keys, values, comparer, 0, middle);  // swap the low with the mid point
+            SwapIfGreaterWithValues(keys, values, comparer, 0, hi);   // swap the low with the high
             SwapIfGreaterWithValues(keys, values, comparer, middle, hi); // swap the middle with the high
 
             TKey pivot = keys[middle];
             Swap(keys, values, middle, hi - 1);
-            int left = lo, right = hi - 1;  // We already partitioned lo and hi and put the pivot in hi - 1.  And we pre-increment & decrement below.
+            int left = 0, right = hi - 1;  // We already partitioned lo and hi and put the pivot in hi - 1.  And we pre-increment & decrement below.
 
             while (left < right)
             {
@@ -745,7 +705,10 @@ namespace System.Collections.Generic
             }
 
             // Put pivot in the right location.
-            Swap(keys, values, left, hi - 1);
+            if (left != hi - 1)
+            {
+                Swap(keys, values, left, hi - 1);
+            }
             return left;
         }
 
@@ -754,19 +717,16 @@ namespace System.Collections.Generic
             Debug.Assert(comparer != null);
             Debug.Assert(!keys.IsEmpty);
 
-            int lo = 0;
-            int hi = keys.Length - 1;
-
-            int n = hi - lo + 1;
-            for (int i = n / 2; i >= 1; i--)
+            int n = keys.Length;
+            for (int i = n >> 1; i >= 1; i--)
             {
-                DownHeap(keys, values, i, n, lo, comparer);
+                DownHeap(keys, values, i, n, 0, comparer);
             }
 
             for (int i = n; i > 1; i--)
             {
-                Swap(keys, values, lo, lo + i - 1);
-                DownHeap(keys, values, 1, i - 1, lo, comparer);
+                Swap(keys, values, 0, i - 1);
+                DownHeap(keys, values, 1, i - 1, 0, comparer);
             }
         }
 
@@ -779,7 +739,7 @@ namespace System.Collections.Generic
             TKey d = keys[lo + i - 1];
             TValue dValue = values[lo + i - 1];
 
-            while (i <= n / 2)
+            while (i <= n >> 1)
             {
                 int child = 2 * i;
                 if (child < n && comparer.Compare(keys[lo + child - 1], keys[lo + child]) < 0)
@@ -842,44 +802,42 @@ namespace System.Collections.Generic
             }
             catch (IndexOutOfRangeException)
             {
-                IntrospectiveSortUtilities.ThrowOrIgnoreBadComparer(comparer);
+                ThrowHelper.ThrowArgumentException_BadComparer(comparer);
             }
             catch (Exception e)
             {
-                throw new InvalidOperationException(SR.InvalidOperation_IComparerFailed, e);
+                ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_IComparerFailed, e);
             }
         }
 
         private static void SwapIfGreaterWithValues(Span<TKey> keys, Span<TValue> values, int i, int j)
         {
-            if (i != j)
-            {
-                if (keys[i] != null && keys[i].CompareTo(keys[j]) > 0)
-                {
-                    TKey key = keys[i];
-                    keys[i] = keys[j];
-                    keys[j] = key;
+            Debug.Assert(i != j);
 
-                    TValue value = values[i];
-                    values[i] = values[j];
-                    values[j] = value;
-                }
+            if (keys[i] != null && keys[i].CompareTo(keys[j]) > 0)
+            {
+                TKey key = keys[i];
+                keys[i] = keys[j];
+                keys[j] = key;
+
+                TValue value = values[i];
+                values[i] = values[j];
+                values[j] = value;
             }
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static void Swap(Span<TKey> keys, Span<TValue> values, int i, int j)
         {
-            if (i != j)
-            {
-                TKey k = keys[i];
-                keys[i] = keys[j];
-                keys[j] = k;
+            Debug.Assert(i != j);
 
-                TValue v = values[i];
-                values[i] = values[j];
-                values[j] = v;
-            }
+            TKey k = keys[i];
+            keys[i] = keys[j];
+            keys[j] = k;
+
+            TValue v = values[i];
+            values[i] = values[j];
+            values[j] = v;
         }
 
         internal static void IntrospectiveSort(Span<TKey> keys, Span<TValue> values)
@@ -888,83 +846,82 @@ namespace System.Collections.Generic
 
             if (keys.Length > 1)
             {
-                IntroSort(keys, values, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(keys.Length));
+                IntroSort(keys, values, 2 * (BitOperations.Log2((uint)keys.Length) + 1));
             }
         }
 
         private static void IntroSort(Span<TKey> keys, Span<TValue> values, int depthLimit)
         {
-            int lo = 0;
-            int hi = keys.Length - 1;
+            Debug.Assert(!keys.IsEmpty);
+            Debug.Assert(values.Length == keys.Length);
+            Debug.Assert(depthLimit >= 0);
 
-            while (hi > lo)
+            int hi = keys.Length - 1;
+            while (hi > 0)
             {
-                int partitionSize = hi - lo + 1;
-                if (partitionSize <= IntrospectiveSortUtilities.IntrosortSizeThreshold)
+                int partitionSize = hi + 1;
+
+                if (partitionSize <= Array.IntrosortSizeThreshold)
                 {
-                    if (partitionSize == 1)
-                    {
-                        return;
-                    }
+                    Debug.Assert(partitionSize >= 2);
 
                     if (partitionSize == 2)
                     {
-                        SwapIfGreaterWithValues(keys, values, lo, hi);
+                        SwapIfGreaterWithValues(keys, values, 0, hi);
                         return;
                     }
 
                     if (partitionSize == 3)
                     {
-                        SwapIfGreaterWithValues(keys, values, lo, hi - 1);
-                        SwapIfGreaterWithValues(keys, values, lo, hi);
+                        SwapIfGreaterWithValues(keys, values, 0, hi - 1);
+                        SwapIfGreaterWithValues(keys, values, 0, hi);
                         SwapIfGreaterWithValues(keys, values, hi - 1, hi);
                         return;
                     }
 
-                    InsertionSort(keys[lo..(hi+1)], values[lo..(hi+1)]);
+                    InsertionSort(keys.Slice(0, partitionSize), values.Slice(0, partitionSize));
                     return;
                 }
 
                 if (depthLimit == 0)
                 {
-                    HeapSort(keys[lo..(hi+1)], values[lo..(hi+1)]);
+                    HeapSort(keys.Slice(0, partitionSize), values.Slice(0, partitionSize));
                     return;
                 }
                 depthLimit--;
 
-                int p = PickPivotAndPartition(keys[lo..(hi+1)], values[lo..(hi+1)]);
+                int p = PickPivotAndPartition(keys.Slice(0, partitionSize), values.Slice(0, partitionSize));
 
                 // Note we've already partitioned around the pivot and do not have to move the pivot again.
-                IntroSort(keys[(p+1)..(hi+1)], values[(p+1)..(hi+1)], depthLimit);
+                IntroSort(keys[(p+1)..partitionSize], values[(p+1)..partitionSize], depthLimit);
                 hi = p - 1;
             }
         }
 
         private static int PickPivotAndPartition(Span<TKey> keys, Span<TValue> values)
         {
-            Debug.Assert(!keys.IsEmpty);
+            Debug.Assert(keys.Length >= Array.IntrosortSizeThreshold);
 
-            int lo = 0;
             int hi = keys.Length - 1;
 
             // Compute median-of-three.  But also partition them, since we've done the comparison.
-            int middle = lo + ((hi - lo) / 2);
+            int middle = hi >> 1;
 
             // Sort lo, mid and hi appropriately, then pick mid as the pivot.
-            SwapIfGreaterWithValues(keys, values, lo, middle);  // swap the low with the mid point
-            SwapIfGreaterWithValues(keys, values, lo, hi);   // swap the low with the high
+            SwapIfGreaterWithValues(keys, values, 0, middle);  // swap the low with the mid point
+            SwapIfGreaterWithValues(keys, values, 0, hi);   // swap the low with the high
             SwapIfGreaterWithValues(keys, values, middle, hi); // swap the middle with the high
 
             TKey pivot = keys[middle];
             Swap(keys, values, middle, hi - 1);
-            int left = lo, right = hi - 1;  // We already partitioned lo and hi and put the pivot in hi - 1.  And we pre-increment & decrement below.
+            int left = 0, right = hi - 1;  // We already partitioned lo and hi and put the pivot in hi - 1.  And we pre-increment & decrement below.
 
             while (left < right)
             {
                 if (pivot == null)
                 {
                     while (left < (hi - 1) && keys[++left] == null) ;
-                    while (right > lo && keys[--right] != null) ;
+                    while (right > 0 && keys[--right] != null) ;
                 }
                 else
                 {
@@ -979,7 +936,10 @@ namespace System.Collections.Generic
             }
 
             // Put pivot in the right location.
-            Swap(keys, values, left, hi - 1);
+            if (left != hi - 1)
+            {
+                Swap(keys, values, left, hi - 1);
+            }
             return left;
         }
 
@@ -987,19 +947,16 @@ namespace System.Collections.Generic
         {
             Debug.Assert(!keys.IsEmpty);
 
-            int lo = 0;
-            int hi = keys.Length - 1;
-
-            int n = hi - lo + 1;
-            for (int i = n / 2; i >= 1; i--)
+            int n = keys.Length;
+            for (int i = n >> 1; i >= 1; i--)
             {
-                DownHeap(keys, values, i, n, lo);
+                DownHeap(keys, values, i, n, 0);
             }
 
             for (int i = n; i > 1; i--)
             {
-                Swap(keys, values, lo, lo + i - 1);
-                DownHeap(keys, values, 1, i - 1, lo);
+                Swap(keys, values, 0, i - 1);
+                DownHeap(keys, values, 1, i - 1, 0);
             }
         }
 
@@ -1011,7 +968,7 @@ namespace System.Collections.Generic
             TKey d = keys[lo + i - 1];
             TValue dValue = values[lo + i - 1];
 
-            while (i <= n / 2)
+            while (i <= n >> 1)
             {
                 int child = 2 * i;
                 if (child < n && (keys[lo + child - 1] == null || keys[lo + child - 1].CompareTo(keys[lo + child]) < 0))

src/System.Private.CoreLib/shared/System/Collections/Generic/Dictionary.cs

@@ -512,7 +512,6 @@ namespace System.Collections.Generic
                             if (behavior == InsertionBehavior.OverwriteExisting)
                             {
                                 entries[i].value = value;
-                                _version++;
                                 return true;
                             }
 
@@ -555,7 +554,6 @@ namespace System.Collections.Generic
                             if (behavior == InsertionBehavior.OverwriteExisting)
                             {
                                 entries[i].value = value;
-                                _version++;
                                 return true;
                             }
 
@@ -595,7 +593,6 @@ namespace System.Collections.Generic
                         if (behavior == InsertionBehavior.OverwriteExisting)
                         {
                             entries[i].value = value;
-                            _version++;
                             return true;
                         }
 

src/System.Private.CoreLib/shared/System/Collections/Generic/IReadOnlySet.cs

@@ -0,0 +1,62 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Collections.Generic
+{
+    /// <summary>
+    /// Provides a readonly abstraction of a set.
+    /// </summary>
+    /// <typeparam name="T">The type of elements in the set.</typeparam>
+    public interface IReadOnlySet<T> : IReadOnlyCollection<T>
+    {
+        /// <summary>
+        /// Determines if the set contains a specific item
+        /// </summary>
+        /// <param name="item">The item to check if the set contains.</param>
+        /// <returns><see langword="true" /> if found; otherwise <see langword="false" />.</returns>
+        bool Contains(T item);
+        /// <summary>
+        /// Determines whether the current set is a proper (strict) subset of a specified collection.
+        /// </summary>
+        /// <param name="other">The collection to compare to the current set.</param>
+        /// <returns><see langword="true" /> if the current set is a proper subset of other; otherwise <see langword="false" />.</returns>
+        /// <exception cref="ArgumentNullException">other is <see langword="null" />.</exception>
+        bool IsProperSubsetOf(IEnumerable<T> other);
+        /// <summary>
+        /// Determines whether the current set is a proper (strict) superset of a specified collection.
+        /// </summary>
+        /// <param name="other">The collection to compare to the current set.</param>
+        /// <returns><see langword="true" /> if the collection is a proper superset of other; otherwise <see langword="false" />.</returns>
+        /// <exception cref="ArgumentNullException">other is <see langword="null" />.</exception>
+        bool IsProperSupersetOf(IEnumerable<T> other);
+        /// <summary>
+        /// Determine whether the current set is a subset of a specified collection.
+        /// </summary>
+        /// <param name="other">The collection to compare to the current set.</param>
+        /// <returns><see langword="true" /> if the current set is a subset of other; otherwise <see langword="false" />.</returns>
+        /// <exception cref="ArgumentNullException">other is <see langword="null" />.</exception>
+        bool IsSubsetOf(IEnumerable<T> other);
+        /// <summary>
+        /// Determine whether the current set is a super set of a specified collection.
+        /// </summary>
+        /// <param name="other">The collection to compare to the current set</param>
+        /// <returns><see langword="true" /> if the current set is a subset of other; otherwise <see langword="false" />.</returns>
+        /// <exception cref="ArgumentNullException">other is <see langword="null" />.</exception>
+        bool IsSupersetOf(IEnumerable<T> other);
+        /// <summary>
+        /// Determines whether the current set overlaps with the specified collection.
+        /// </summary>
+        /// <param name="other">The collection to compare to the current set.</param>
+        /// <returns><see langword="true" />if the current set and other share at least one common element; otherwise, <see langword="false" />.</returns>
+        /// <exception cref="ArgumentNullException">other is <see langword="null" />.</exception>
+        bool Overlaps(IEnumerable<T> other);
+        /// <summary>
+        /// Determines whether the current set and the specified collection contain the same elements.
+        /// </summary>
+        /// <param name="other">The collection to compare to the current set.</param>
+        /// <returns><see langword="true" /> if the current set is equal to other; otherwise, <see langword="false" />.</returns>
+        /// <exception cref="ArgumentNullException">other is <see langword="null" />.</exception>
+        bool SetEquals(IEnumerable<T> other);
+    }
+}

src/System.Private.CoreLib/shared/System/Collections/Generic/ISet.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System.Runtime.CompilerServices;
-
 namespace System.Collections.Generic
 {
     /// <summary>

src/System.Private.CoreLib/shared/System/Collections/Hashtable.cs

@@ -480,11 +480,9 @@ namespace System.Collections
                 throw new ArgumentNullException(nameof(key), SR.ArgumentNull_Key);
             }
 
-            uint seed;
-            uint incr;
             // Take a snapshot of buckets, in case another thread resizes table
             bucket[] lbuckets = _buckets;
-            uint hashcode = InitHash(key, lbuckets.Length, out seed, out incr);
+            uint hashcode = InitHash(key, lbuckets.Length, out uint seed, out uint incr);
             int ntry = 0;
 
             bucket b;
@@ -639,12 +637,10 @@ namespace System.Collections
                     throw new ArgumentNullException(nameof(key), SR.ArgumentNull_Key);
                 }
 
-                uint seed;
-                uint incr;
 
                 // Take a snapshot of buckets, in case another thread does a resize
                 bucket[] lbuckets = _buckets;
-                uint hashcode = InitHash(key, lbuckets.Length, out seed, out incr);
+                uint hashcode = InitHash(key, lbuckets.Length, out uint seed, out uint incr);
                 int ntry = 0;
 
                 bucket b;
@@ -858,11 +854,9 @@ namespace System.Collections
                 rehash();
             }
 
-            uint seed;
-            uint incr;
             // Assume we only have one thread writing concurrently.  Modify
             // buckets to contain new data, as long as we insert in the right order.
-            uint hashcode = InitHash(key, _buckets.Length, out seed, out incr);
+            uint hashcode = InitHash(key, _buckets.Length, out uint seed, out uint incr);
             int ntry = 0;
             int emptySlotNumber = -1; // We use the empty slot number to cache the first empty slot. We chose to reuse slots
             // create by remove that have the collision bit set over using up new slots.
@@ -994,10 +988,8 @@ namespace System.Collections
 
             Debug.Assert(!_isWriterInProgress, "Race condition detected in usages of Hashtable - multiple threads appear to be writing to a Hashtable instance simultaneously!  Don't do that - use Hashtable.Synchronized.");
 
-            uint seed;
-            uint incr;
             // Assuming only one concurrent writer, write directly into buckets.
-            uint hashcode = InitHash(key, _buckets.Length, out seed, out incr);
+            uint hashcode = InitHash(key, _buckets.Length, out uint seed, out uint incr);
             int ntry = 0;
 
             bucket b;
@@ -1116,8 +1108,7 @@ namespace System.Collections
                 return;
             }
 
-            SerializationInfo? siInfo;
-            HashHelpers.SerializationInfoTable.TryGetValue(this, out siInfo);
+            HashHelpers.SerializationInfoTable.TryGetValue(this, out SerializationInfo? siInfo);
 
             if (siInfo == null)
             {

src/System.Private.CoreLib/shared/System/Convert.cs

@@ -528,11 +528,7 @@ namespace System
             return (char)value;
         }
 
-        public static char ToChar(int value)
-        {
-            if (value < 0 || value > char.MaxValue) ThrowCharOverflowException();
-            return (char)value;
-        }
+        public static char ToChar(int value) => ToChar((uint)value);
 
         [CLSCompliant(false)]
         public static char ToChar(uint value)
@@ -541,11 +537,7 @@ namespace System
             return (char)value;
         }
 
-        public static char ToChar(long value)
-        {
-            if (value < 0 || value > char.MaxValue) ThrowCharOverflowException();
-            return (char)value;
-        }
+        public static char ToChar(long value) => ToChar((ulong)value);
 
         [CLSCompliant(false)]
         public static char ToChar(ulong value)
@@ -667,7 +659,7 @@ namespace System
         [CLSCompliant(false)]
         public static sbyte ToSByte(uint value)
         {
-            if (value > sbyte.MaxValue) ThrowSByteOverflowException();
+            if (value > (uint)sbyte.MaxValue) ThrowSByteOverflowException();
             return (sbyte)value;
         }
 
@@ -708,13 +700,13 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return sbyte.Parse(value, CultureInfo.CurrentCulture);
+            return sbyte.Parse(value);
         }
 
         [CLSCompliant(false)]
         public static sbyte ToSByte(string value, IFormatProvider? provider)
         {
-            return sbyte.Parse(value, NumberStyles.Integer, provider);
+            return sbyte.Parse(value, provider);
         }
 
         [CLSCompliant(false)]
@@ -757,13 +749,13 @@ namespace System
         [CLSCompliant(false)]
         public static byte ToByte(sbyte value)
         {
-            if (value < byte.MinValue) ThrowByteOverflowException();
+            if (value < 0) ThrowByteOverflowException();
             return (byte)value;
         }
 
         public static byte ToByte(short value)
         {
-            if (value < byte.MinValue || value > byte.MaxValue) ThrowByteOverflowException();
+            if ((uint)value > byte.MaxValue) ThrowByteOverflowException();
             return (byte)value;
         }
 
@@ -774,11 +766,7 @@ namespace System
             return (byte)value;
         }
 
-        public static byte ToByte(int value)
-        {
-            if (value < byte.MinValue || value > byte.MaxValue) ThrowByteOverflowException();
-            return (byte)value;
-        }
+        public static byte ToByte(int value) => ToByte((uint)value);
 
         [CLSCompliant(false)]
         public static byte ToByte(uint value)
@@ -787,11 +775,7 @@ namespace System
             return (byte)value;
         }
 
-        public static byte ToByte(long value)
-        {
-            if (value < byte.MinValue || value > byte.MaxValue) ThrowByteOverflowException();
-            return (byte)value;
-        }
+        public static byte ToByte(long value) => ToByte((ulong)value);
 
         [CLSCompliant(false)]
         public static byte ToByte(ulong value)
@@ -819,14 +803,14 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return byte.Parse(value, CultureInfo.CurrentCulture);
+            return byte.Parse(value);
         }
 
         public static byte ToByte(string? value, IFormatProvider? provider)
         {
             if (value == null)
                 return 0;
-            return byte.Parse(value, NumberStyles.Integer, provider);
+            return byte.Parse(value, provider);
         }
 
         public static byte ToByte(DateTime value)
@@ -887,7 +871,7 @@ namespace System
         [CLSCompliant(false)]
         public static short ToInt16(uint value)
         {
-            if (value > short.MaxValue) ThrowInt16OverflowException();
+            if (value > (uint)short.MaxValue) ThrowInt16OverflowException();
             return (short)value;
         }
 
@@ -928,14 +912,14 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return short.Parse(value, CultureInfo.CurrentCulture);
+            return short.Parse(value);
         }
 
         public static short ToInt16(string? value, IFormatProvider? provider)
         {
             if (value == null)
                 return 0;
-            return short.Parse(value, NumberStyles.Integer, provider);
+            return short.Parse(value, provider);
         }
 
         public static short ToInt16(DateTime value)
@@ -993,11 +977,7 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static ushort ToUInt16(int value)
-        {
-            if (value < 0 || value > ushort.MaxValue) ThrowUInt16OverflowException();
-            return (ushort)value;
-        }
+        public static ushort ToUInt16(int value) => ToUInt16((uint)value);
 
         [CLSCompliant(false)]
         public static ushort ToUInt16(ushort value)
@@ -1013,11 +993,7 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static ushort ToUInt16(long value)
-        {
-            if (value < 0 || value > ushort.MaxValue) ThrowUInt16OverflowException();
-            return (ushort)value;
-        }
+        public static ushort ToUInt16(long value) => ToUInt16((ulong)value);
 
         [CLSCompliant(false)]
         public static ushort ToUInt16(ulong value)
@@ -1049,7 +1025,7 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return ushort.Parse(value, CultureInfo.CurrentCulture);
+            return ushort.Parse(value);
         }
 
         [CLSCompliant(false)]
@@ -1057,7 +1033,7 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return ushort.Parse(value, NumberStyles.Integer, provider);
+            return ushort.Parse(value, provider);
         }
 
         [CLSCompliant(false)]
@@ -1116,7 +1092,7 @@ namespace System
         [CLSCompliant(false)]
         public static int ToInt32(uint value)
         {
-            if (value > int.MaxValue) ThrowInt32OverflowException();
+            if ((int)value < 0) ThrowInt32OverflowException();
             return (int)value;
         }
 
@@ -1177,14 +1153,14 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return int.Parse(value, CultureInfo.CurrentCulture);
+            return int.Parse(value);
         }
 
         public static int ToInt32(string? value, IFormatProvider? provider)
         {
             if (value == null)
                 return 0;
-            return int.Parse(value, NumberStyles.Integer, provider);
+            return int.Parse(value, provider);
         }
 
         public static int ToInt32(DateTime value)
@@ -1261,11 +1237,7 @@ namespace System
         }
 
         [CLSCompliant(false)]
-        public static uint ToUInt32(long value)
-        {
-            if (value < 0 || value > uint.MaxValue) ThrowUInt32OverflowException();
-            return (uint)value;
-        }
+        public static uint ToUInt32(long value) => ToUInt32((ulong)value);
 
         [CLSCompliant(false)]
         public static uint ToUInt32(ulong value)
@@ -1304,7 +1276,7 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return uint.Parse(value, CultureInfo.CurrentCulture);
+            return uint.Parse(value);
         }
 
         [CLSCompliant(false)]
@@ -1312,7 +1284,7 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return uint.Parse(value, NumberStyles.Integer, provider);
+            return uint.Parse(value, provider);
         }
 
         [CLSCompliant(false)]
@@ -1382,7 +1354,7 @@ namespace System
         [CLSCompliant(false)]
         public static long ToInt64(ulong value)
         {
-            if (value > long.MaxValue) ThrowInt64OverflowException();
+            if ((long)value < 0) ThrowInt64OverflowException();
             return (long)value;
         }
 
@@ -1410,14 +1382,14 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return long.Parse(value, CultureInfo.CurrentCulture);
+            return long.Parse(value);
         }
 
         public static long ToInt64(string? value, IFormatProvider? provider)
         {
             if (value == null)
                 return 0;
-            return long.Parse(value, NumberStyles.Integer, provider);
+            return long.Parse(value, provider);
         }
 
         public static long ToInt64(DateTime value)
@@ -1529,7 +1501,7 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return ulong.Parse(value, CultureInfo.CurrentCulture);
+            return ulong.Parse(value);
         }
 
         [CLSCompliant(false)]
@@ -1537,7 +1509,7 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return ulong.Parse(value, NumberStyles.Integer, provider);
+            return ulong.Parse(value, provider);
         }
 
         [CLSCompliant(false)]
@@ -1629,14 +1601,14 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return float.Parse(value, CultureInfo.CurrentCulture);
+            return float.Parse(value);
         }
 
         public static float ToSingle(string? value, IFormatProvider? provider)
         {
             if (value == null)
                 return 0;
-            return float.Parse(value, NumberStyles.Float | NumberStyles.AllowThousands, provider);
+            return float.Parse(value, provider);
         }
 
         public static float ToSingle(bool value)
@@ -1732,14 +1704,14 @@ namespace System
         {
             if (value == null)
                 return 0;
-            return double.Parse(value, CultureInfo.CurrentCulture);
+            return double.Parse(value);
         }
 
         public static double ToDouble(string? value, IFormatProvider? provider)
         {
             if (value == null)
                 return 0;
-            return double.Parse(value, NumberStyles.Float | NumberStyles.AllowThousands, provider);
+            return double.Parse(value, provider);
         }
 
         public static double ToDouble(bool value)
@@ -1830,14 +1802,14 @@ namespace System
         {
             if (value == null)
                 return 0m;
-            return decimal.Parse(value, CultureInfo.CurrentCulture);
+            return decimal.Parse(value);
         }
 
         public static decimal ToDecimal(string? value, IFormatProvider? provider)
         {
             if (value == null)
                 return 0m;
-            return decimal.Parse(value, NumberStyles.Number, provider);
+            return decimal.Parse(value, provider);
         }
 
         public static decimal ToDecimal(decimal value)
@@ -1879,7 +1851,7 @@ namespace System
         {
             if (value == null)
                 return new DateTime(0);
-            return DateTime.Parse(value, CultureInfo.CurrentCulture);
+            return DateTime.Parse(value);
         }
 
         public static DateTime ToDateTime(string? value, IFormatProvider? provider)
@@ -2000,7 +1972,7 @@ namespace System
         [CLSCompliant(false)]
         public static string ToString(sbyte value)
         {
-            return value.ToString(CultureInfo.CurrentCulture);
+            return value.ToString();
         }
 
         [CLSCompliant(false)]
@@ -2011,7 +1983,7 @@ namespace System
 
         public static string ToString(byte value)
         {
-            return value.ToString(CultureInfo.CurrentCulture);
+            return value.ToString();
         }
 
         public static string ToString(byte value, IFormatProvider? provider)
@@ -2021,7 +1993,7 @@ namespace System
 
         public static string ToString(short value)
         {
-            return value.ToString(CultureInfo.CurrentCulture);
+            return value.ToString();
         }
 
         public static string ToString(short value, IFormatProvider? provider)
@@ -2032,7 +2004,7 @@ namespace System
         [CLSCompliant(false)]
         public static string ToString(ushort value)
         {
-            return value.ToString(CultureInfo.CurrentCulture);
+            return value.ToString();
         }
 
         [CLSCompliant(false)]
@@ -2043,7 +2015,7 @@ namespace System
 
         public static string ToString(int value)
         {
-            return value.ToString(CultureInfo.CurrentCulture);
+            return value.ToString();
         }
 
         public static string ToString(int value, IFormatProvider? provider)
@@ -2054,7 +2026,7 @@ namespace System
         [CLSCompliant(false)]
         public static string ToString(uint value)
         {
-            return value.ToString(CultureInfo.CurrentCulture);
+            return value.ToString();
         }
 
         [CLSCompliant(false)]
@@ -2065,7 +2037,7 @@ namespace System
 
         public static string ToString(long value)
         {
-            return value.ToString(CultureInfo.CurrentCulture);
+            return value.ToString();
         }
 
         public static string ToString(long value, IFormatProvider? provider)
@@ -2076,7 +2048,7 @@ namespace System
         [CLSCompliant(false)]
         public static string ToString(ulong value)
         {
-            return value.ToString(CultureInfo.CurrentCulture);
+            return value.ToString();
         }
 
         [CLSCompliant(false)]
@@ -2087,7 +2059,7 @@ namespace System
 
         public static string ToString(float value)
         {
-            return value.ToString(CultureInfo.CurrentCulture);
+            return value.ToString();
         }
 
         public static string ToString(float value, IFormatProvider? provider)
@@ -2097,7 +2069,7 @@ namespace System
 
         public static string ToString(double value)
         {
-            return value.ToString(CultureInfo.CurrentCulture);
+            return value.ToString();
         }
 
         public static string ToString(double value, IFormatProvider? provider)
@@ -2107,7 +2079,7 @@ namespace System
 
         public static string ToString(decimal value)
         {
-            return value.ToString(CultureInfo.CurrentCulture);
+            return value.ToString();
         }
 
         public static string ToString(decimal value, IFormatProvider? provider)
@@ -2157,7 +2129,7 @@ namespace System
             }
 
             int r = ParseNumbers.StringToInt(value.AsSpan(), fromBase, ParseNumbers.IsTight | ParseNumbers.TreatAsUnsigned);
-            if (r < byte.MinValue || r > byte.MaxValue)
+            if ((uint)r > byte.MaxValue)
                 ThrowByteOverflowException();
             return (byte)r;
         }
@@ -2231,7 +2203,7 @@ namespace System
             }
 
             int r = ParseNumbers.StringToInt(value.AsSpan(), fromBase, ParseNumbers.IsTight | ParseNumbers.TreatAsUnsigned);
-            if (r < ushort.MinValue || r > ushort.MaxValue)
+            if ((uint)r > ushort.MaxValue)
                 ThrowUInt16OverflowException();
             return (ushort)r;
         }

src/System.Private.CoreLib/shared/System/DateTime.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Runtime.InteropServices;
 using System.Runtime.CompilerServices;
@@ -751,8 +752,7 @@ namespace System
                     // Because the ticks conversion between UTC and local is lossy, we need to capture whether the
                     // time is in a repeated hour so that it can be passed to the DateTime constructor.
                     DateTime utcDt = new DateTime(ticks, DateTimeKind.Utc);
-                    bool isDaylightSavings = false;
-                    offsetTicks = TimeZoneInfo.GetUtcOffsetFromUtc(utcDt, TimeZoneInfo.Local, out isDaylightSavings, out isAmbiguousLocalDst).Ticks;
+                    offsetTicks = TimeZoneInfo.GetUtcOffsetFromUtc(utcDt, TimeZoneInfo.Local, out bool isDaylightSavings, out isAmbiguousLocalDst).Ticks;
                 }
                 ticks += offsetTicks;
                 // Another behaviour of parsing is to cause small times to wrap around, so that they can be used
@@ -1079,8 +1079,7 @@ namespace System
             get
             {
                 DateTime utc = UtcNow;
-                bool isAmbiguousLocalDst;
-                long offset = TimeZoneInfo.GetDateTimeNowUtcOffsetFromUtc(utc, out isAmbiguousLocalDst).Ticks;
+                long offset = TimeZoneInfo.GetDateTimeNowUtcOffsetFromUtc(utc, out bool isAmbiguousLocalDst).Ticks;
                 long tick = utc.Ticks + offset;
                 if (tick > DateTime.MaxTicks)
                 {
@@ -1290,9 +1289,7 @@ namespace System
             {
                 return this;
             }
-            bool isDaylightSavings = false;
-            bool isAmbiguousLocalDst = false;
-            long offset = TimeZoneInfo.GetUtcOffsetFromUtc(this, TimeZoneInfo.Local, out isDaylightSavings, out isAmbiguousLocalDst).Ticks;
+            long offset = TimeZoneInfo.GetUtcOffsetFromUtc(this, TimeZoneInfo.Local, out bool isDaylightSavings, out bool isAmbiguousLocalDst).Ticks;
             long tick = Ticks + offset;
             if (tick > DateTime.MaxTicks)
             {
@@ -1359,7 +1356,7 @@ namespace System
             return TimeZoneInfo.ConvertTimeToUtc(this, TimeZoneInfoOptions.NoThrowOnInvalidTime);
         }
 
-        public static bool TryParse(string? s, out DateTime result)
+        public static bool TryParse([NotNullWhen(true)] string? s, out DateTime result)
         {
             if (s == null)
             {
@@ -1374,7 +1371,7 @@ namespace System
             return DateTimeParse.TryParse(s, DateTimeFormatInfo.CurrentInfo, DateTimeStyles.None, out result);
         }
 
-        public static bool TryParse(string? s, IFormatProvider? provider, DateTimeStyles styles, out DateTime result)
+        public static bool TryParse([NotNullWhen(true)] string? s, IFormatProvider? provider, DateTimeStyles styles, out DateTime result)
         {
             DateTimeFormatInfo.ValidateStyles(styles, nameof(styles));
 
@@ -1393,7 +1390,7 @@ namespace System
             return DateTimeParse.TryParse(s, DateTimeFormatInfo.GetInstance(provider), styles, out result);
         }
 
-        public static bool TryParseExact(string? s, string? format, IFormatProvider? provider, DateTimeStyles style, out DateTime result)
+        public static bool TryParseExact([NotNullWhen(true)] string? s, [NotNullWhen(true)] string? format, IFormatProvider? provider, DateTimeStyles style, out DateTime result)
         {
             DateTimeFormatInfo.ValidateStyles(style, nameof(style));
 
@@ -1412,7 +1409,7 @@ namespace System
             return DateTimeParse.TryParseExact(s, format, DateTimeFormatInfo.GetInstance(provider), style, out result);
         }
 
-        public static bool TryParseExact(string? s, string?[]? formats, IFormatProvider? provider, DateTimeStyles style, out DateTime result)
+        public static bool TryParseExact([NotNullWhen(true)] string? s, [NotNullWhen(true)] string?[]? formats, IFormatProvider? provider, DateTimeStyles style, out DateTime result)
         {
             DateTimeFormatInfo.ValidateStyles(style, nameof(style));
 
@@ -1425,7 +1422,7 @@ namespace System
             return DateTimeParse.TryParseExactMultiple(s, formats, DateTimeFormatInfo.GetInstance(provider), style, out result);
         }
 
-        public static bool TryParseExact(ReadOnlySpan<char> s, string?[]? formats, IFormatProvider? provider, DateTimeStyles style, out DateTime result)
+        public static bool TryParseExact(ReadOnlySpan<char> s, [NotNullWhen(true)] string?[]? formats, IFormatProvider? provider, DateTimeStyles style, out DateTime result)
         {
             DateTimeFormatInfo.ValidateStyles(style, nameof(style));
             return DateTimeParse.TryParseExactMultiple(s, formats, DateTimeFormatInfo.GetInstance(provider), style, out result);

src/System.Private.CoreLib/shared/System/DateTimeOffset.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Runtime.InteropServices;
 using System.Runtime.Serialization;
@@ -479,11 +480,10 @@ namespace System
         {
             if (input == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.input);
 
-            TimeSpan offset;
             DateTime dateResult = DateTimeParse.Parse(input,
                                                       DateTimeFormatInfo.CurrentInfo,
                                                       DateTimeStyles.None,
-                                                      out offset);
+                                                      out TimeSpan offset);
             return new DateTimeOffset(dateResult.Ticks, offset);
         }
 
@@ -502,11 +502,10 @@ namespace System
             styles = ValidateStyles(styles, nameof(styles));
             if (input == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.input);
 
-            TimeSpan offset;
             DateTime dateResult = DateTimeParse.Parse(input,
                                                       DateTimeFormatInfo.GetInstance(formatProvider),
                                                       styles,
-                                                      out offset);
+                                                      out TimeSpan offset);
             return new DateTimeOffset(dateResult.Ticks, offset);
         }
 
@@ -538,12 +537,11 @@ namespace System
             if (input == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.input);
             if (format == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.format);
 
-            TimeSpan offset;
             DateTime dateResult = DateTimeParse.ParseExact(input,
                                                            format,
                                                            DateTimeFormatInfo.GetInstance(formatProvider),
                                                            styles,
-                                                           out offset);
+                                                           out TimeSpan offset);
             return new DateTimeOffset(dateResult.Ticks, offset);
         }
 
@@ -559,12 +557,11 @@ namespace System
             styles = ValidateStyles(styles, nameof(styles));
             if (input == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.input);
 
-            TimeSpan offset;
             DateTime dateResult = DateTimeParse.ParseExactMultiple(input,
                                                                    formats,
                                                                    DateTimeFormatInfo.GetInstance(formatProvider),
                                                                    styles,
-                                                                   out offset);
+                                                                   out TimeSpan offset);
             return new DateTimeOffset(dateResult.Ticks, offset);
         }
 
@@ -652,15 +649,13 @@ namespace System
         public DateTimeOffset ToUniversalTime() =>
             new DateTimeOffset(UtcDateTime);
 
-        public static bool TryParse(string? input, out DateTimeOffset result)
+        public static bool TryParse([NotNullWhen(true)] string? input, out DateTimeOffset result)
         {
-            TimeSpan offset;
-            DateTime dateResult;
             bool parsed = DateTimeParse.TryParse(input,
                                                     DateTimeFormatInfo.CurrentInfo,
                                                     DateTimeStyles.None,
-                                                    out dateResult,
-                                                    out offset);
+                                                    out DateTime dateResult,
+                                                    out TimeSpan offset);
             result = new DateTimeOffset(dateResult.Ticks, offset);
             return parsed;
         }
@@ -672,7 +667,7 @@ namespace System
             return parsed;
         }
 
-        public static bool TryParse(string? input, IFormatProvider? formatProvider, DateTimeStyles styles, out DateTimeOffset result)
+        public static bool TryParse([NotNullWhen(true)] string? input, IFormatProvider? formatProvider, DateTimeStyles styles, out DateTimeOffset result)
         {
             styles = ValidateStyles(styles, nameof(styles));
             if (input == null)
@@ -681,13 +676,11 @@ namespace System
                 return false;
             }
 
-            TimeSpan offset;
-            DateTime dateResult;
             bool parsed = DateTimeParse.TryParse(input,
                                                     DateTimeFormatInfo.GetInstance(formatProvider),
                                                     styles,
-                                                    out dateResult,
-                                                    out offset);
+                                                    out DateTime dateResult,
+                                                    out TimeSpan offset);
             result = new DateTimeOffset(dateResult.Ticks, offset);
             return parsed;
         }
@@ -700,7 +693,7 @@ namespace System
             return parsed;
         }
 
-        public static bool TryParseExact(string? input, string? format, IFormatProvider? formatProvider, DateTimeStyles styles,
+        public static bool TryParseExact([NotNullWhen(true)] string? input, [NotNullWhen(true)] string? format, IFormatProvider? formatProvider, DateTimeStyles styles,
                                             out DateTimeOffset result)
         {
             styles = ValidateStyles(styles, nameof(styles));
@@ -710,14 +703,12 @@ namespace System
                 return false;
             }
 
-            TimeSpan offset;
-            DateTime dateResult;
             bool parsed = DateTimeParse.TryParseExact(input,
                                                          format,
                                                          DateTimeFormatInfo.GetInstance(formatProvider),
                                                          styles,
-                                                         out dateResult,
-                                                         out offset);
+                                                         out DateTime dateResult,
+                                                         out TimeSpan offset);
             result = new DateTimeOffset(dateResult.Ticks, offset);
             return parsed;
         }
@@ -731,7 +722,7 @@ namespace System
             return parsed;
         }
 
-        public static bool TryParseExact(string? input, string?[]? formats, IFormatProvider? formatProvider, DateTimeStyles styles,
+        public static bool TryParseExact([NotNullWhen(true)] string? input, [NotNullWhen(true)] string?[]? formats, IFormatProvider? formatProvider, DateTimeStyles styles,
                                             out DateTimeOffset result)
         {
             styles = ValidateStyles(styles, nameof(styles));
@@ -741,20 +732,18 @@ namespace System
                 return false;
             }
 
-            TimeSpan offset;
-            DateTime dateResult;
             bool parsed = DateTimeParse.TryParseExactMultiple(input,
                                                                  formats,
                                                                  DateTimeFormatInfo.GetInstance(formatProvider),
                                                                  styles,
-                                                                 out dateResult,
-                                                                 out offset);
+                                                                 out DateTime dateResult,
+                                                                 out TimeSpan offset);
             result = new DateTimeOffset(dateResult.Ticks, offset);
             return parsed;
         }
 
         public static bool TryParseExact(
-            ReadOnlySpan<char> input, string?[]? formats, IFormatProvider? formatProvider, DateTimeStyles styles, out DateTimeOffset result)
+            ReadOnlySpan<char> input, [NotNullWhen(true)] string?[]? formats, IFormatProvider? formatProvider, DateTimeStyles styles, out DateTimeOffset result)
         {
             styles = ValidateStyles(styles, nameof(styles));
             bool parsed = DateTimeParse.TryParseExactMultiple(input, formats, DateTimeFormatInfo.GetInstance(formatProvider), styles, out DateTime dateResult, out TimeSpan offset);

src/System.Private.CoreLib/shared/System/Decimal.cs

@@ -4,6 +4,7 @@
 
 using System.Buffers.Binary;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -480,7 +481,7 @@ namespace System
             return Number.ParseDecimal(s, style, NumberFormatInfo.GetInstance(provider));
         }
 
-        public static bool TryParse(string? s, out decimal result)
+        public static bool TryParse([NotNullWhen(true)] string? s, out decimal result)
         {
             if (s == null)
             {
@@ -496,7 +497,7 @@ namespace System
             return Number.TryParseDecimal(s, NumberStyles.Number, NumberFormatInfo.CurrentInfo, out result) == Number.ParsingStatus.OK;
         }
 
-        public static bool TryParse(string? s, NumberStyles style, IFormatProvider? provider, out decimal result)
+        public static bool TryParse([NotNullWhen(true)] string? s, NumberStyles style, IFormatProvider? provider, out decimal result)
         {
             NumberFormatInfo.ValidateParseStyleFloatingPoint(style);
 
@@ -936,9 +937,9 @@ namespace System
         [CLSCompliant(false)]
         public static explicit operator ulong(decimal value) => ToUInt64(value);
 
-        public static explicit operator float(decimal value) => ToSingle(value);
+        public static explicit operator float(decimal value) => DecCalc.VarR4FromDec(in value);
 
-        public static explicit operator double(decimal value) => ToDouble(value);
+        public static explicit operator double(decimal value) => DecCalc.VarR8FromDec(in value);
 
         public static decimal operator +(decimal d) => d;
 
@@ -1051,12 +1052,12 @@ namespace System
 
         float IConvertible.ToSingle(IFormatProvider? provider)
         {
-            return Convert.ToSingle(this);
+            return DecCalc.VarR4FromDec(in this);
         }
 
         double IConvertible.ToDouble(IFormatProvider? provider)
         {
-            return Convert.ToDouble(this);
+            return DecCalc.VarR8FromDec(in this);
         }
 
         decimal IConvertible.ToDecimal(IFormatProvider? provider)

src/System.Private.CoreLib/shared/System/DefaultBinder.cs

@@ -600,7 +600,6 @@ namespace System
                 {
                     if (newMin == 2)
                     {
-                        currentMin = i;
                         ambig = false;
                         currentMin = i;
                     }

src/System.Private.CoreLib/shared/System/Diagnostics/CodeAnalysis/NullableAttributes.cs

@@ -125,4 +125,71 @@ namespace System.Diagnostics.CodeAnalysis
         /// <summary>Gets the condition parameter value.</summary>
         public bool ParameterValue { get; }
     }
+
+    /// <summary>Specifies that the method or property will ensure that the listed field and property members have not-null values.</summary>
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
+#if INTERNAL_NULLABLE_ATTRIBUTES
+    internal
+#else
+    public
+#endif
+        sealed class MemberNotNullAttribute : Attribute
+    {
+        /// <summary>Initializes the attribute with a field or property member.</summary>
+        /// <param name="member">
+        /// The field or property member that is promised to be not-null.
+        /// </param>
+        public MemberNotNullAttribute(string member) => Members = new[] { member };
+
+        /// <summary>Initializes the attribute with the list of field and property members.</summary>
+        /// <param name="members">
+        /// The list of field and property members that are promised to be not-null.
+        /// </param>
+        public MemberNotNullAttribute(params string[] members) => Members = members;
+
+        /// <summary>Gets field or property member names.</summary>
+        public string[] Members { get; }
+    }
+
+    /// <summary>Specifies that the method or property will ensure that the listed field and property members have not-null values when returning with the specified return value condition.</summary>
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
+#if INTERNAL_NULLABLE_ATTRIBUTES
+    internal
+#else
+    public
+#endif
+        sealed class MemberNotNullWhenAttribute : Attribute
+    {
+        /// <summary>Initializes the attribute with the specified return value condition and a field or property member.</summary>
+        /// <param name="returnValue">
+        /// The return value condition. If the method returns this value, the associated parameter will not be null.
+        /// </param>
+        /// <param name="member">
+        /// The field or property member that is promised to be not-null.
+        /// </param>
+        public MemberNotNullWhenAttribute(bool returnValue, string member)
+        {
+            ReturnValue = returnValue;
+            Members = new[] { member };
+        }
+
+        /// <summary>Initializes the attribute with the specified return value condition and list of field and property members.</summary>
+        /// <param name="returnValue">
+        /// The return value condition. If the method returns this value, the associated parameter will not be null.
+        /// </param>
+        /// <param name="members">
+        /// The list of field and property members that are promised to be not-null.
+        /// </param>
+        public MemberNotNullWhenAttribute(bool returnValue, params string[] members)
+        {
+            ReturnValue = returnValue;
+            Members = members;
+        }
+
+        /// <summary>Gets the return value condition.</summary>
+        public bool ReturnValue { get; }
+
+        /// <summary>Gets field or property member names.</summary>
+        public string[] Members { get; }
+    }
 }

src/System.Private.CoreLib/shared/System/Diagnostics/DebugProvider.Unix.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using Microsoft.Win32.SafeHandles;
-
 namespace System.Diagnostics
 {
     public partial class DebugProvider
@@ -56,7 +54,7 @@ namespace System.Diagnostics
             }
             else
             {
-                Interop.Sys.SysLog(Interop.Sys.SysLogPriority.LOG_USER | Interop.Sys.SysLogPriority.LOG_DEBUG, "%s", message);
+                Interop.Sys.SysLog(Interop.Sys.SysLogPriority.LOG_DEBUG, "%s", message);
             }
         }
 
@@ -89,7 +87,7 @@ namespace System.Diagnostics
                     int totalBytesWritten = 0;
                     while (bufCount > 0)
                     {
-                        int bytesWritten = Interop.Sys.Write(2 /* stderr */, buf + totalBytesWritten, bufCount);
+                        int bytesWritten = Interop.Sys.Write((IntPtr)2 /* stderr */, buf + totalBytesWritten, bufCount);
                         if (bytesWritten < 0)
                         {
                             // On error, simply stop writing the debug output.  This could commonly happen if stderr

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/CounterGroup.cs

@@ -102,8 +102,7 @@ namespace System.Diagnostics.Tracing
                 EnsureEventSourceIndexAvailable(eventSourceIndex);
                 Debug.Assert(s_counterGroups != null);
                 WeakReference<CounterGroup> weakRef = CounterGroup.s_counterGroups[eventSourceIndex];
-                CounterGroup? ret = null;
-                if (weakRef == null || !weakRef.TryGetTarget(out ret))
+                if (weakRef == null || !weakRef.TryGetTarget(out CounterGroup? ret))
                 {
                     ret = new CounterGroup(eventSource);
                     CounterGroup.s_counterGroups[eventSourceIndex] = new WeakReference<CounterGroup>(ret);

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventPipe.cs

@@ -0,0 +1,277 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Threading;
+
+#if FEATURE_PERFTRACING
+
+namespace System.Diagnostics.Tracing
+{
+    [StructLayout(LayoutKind.Sequential)]
+    internal struct EventPipeEventInstanceData
+    {
+        internal IntPtr ProviderID;
+        internal uint EventID;
+        internal uint ThreadID;
+        internal long TimeStamp;
+        internal Guid ActivityId;
+        internal Guid ChildActivityId;
+        internal IntPtr Payload;
+        internal uint PayloadLength;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    internal struct EventPipeSessionInfo
+    {
+        internal long StartTimeAsUTCFileTime;
+        internal long StartTimeStamp;
+        internal long TimeStampFrequency;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    internal struct EventPipeProviderConfiguration
+    {
+        [MarshalAs(UnmanagedType.LPWStr)]
+        private readonly string m_providerName;
+        private readonly ulong m_keywords;
+        private readonly uint m_loggingLevel;
+
+        [MarshalAs(UnmanagedType.LPWStr)]
+        private readonly string? m_filterData;
+
+        internal EventPipeProviderConfiguration(
+            string providerName,
+            ulong keywords,
+            uint loggingLevel,
+            string? filterData)
+        {
+            if (string.IsNullOrEmpty(providerName))
+            {
+                throw new ArgumentNullException(nameof(providerName));
+            }
+            if (loggingLevel > 5) // 5 == Verbose, the highest value in EventPipeLoggingLevel.
+            {
+                throw new ArgumentOutOfRangeException(nameof(loggingLevel));
+            }
+            m_providerName = providerName;
+            m_keywords = keywords;
+            m_loggingLevel = loggingLevel;
+            m_filterData = filterData;
+        }
+
+        internal string ProviderName
+        {
+            get { return m_providerName; }
+        }
+
+        internal ulong Keywords
+        {
+            get { return m_keywords; }
+        }
+
+        internal uint LoggingLevel
+        {
+            get { return m_loggingLevel; }
+        }
+
+        internal string? FilterData => m_filterData;
+    }
+
+    internal enum EventPipeSerializationFormat
+    {
+        NetPerf,
+        NetTrace
+    }
+
+    internal sealed class EventPipeWaitHandle : WaitHandle
+    {
+    }
+
+    internal sealed class EventPipeConfiguration
+    {
+        private readonly string m_outputFile;
+        private readonly EventPipeSerializationFormat m_format;
+        private readonly uint m_circularBufferSizeInMB;
+        private readonly List<EventPipeProviderConfiguration> m_providers;
+        private TimeSpan m_minTimeBetweenSamples = TimeSpan.FromMilliseconds(1);
+
+        internal EventPipeConfiguration(
+            string outputFile,
+            EventPipeSerializationFormat format,
+            uint circularBufferSizeInMB)
+        {
+            if (string.IsNullOrEmpty(outputFile))
+            {
+                throw new ArgumentNullException(nameof(outputFile));
+            }
+            if (circularBufferSizeInMB == 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(circularBufferSizeInMB));
+            }
+            m_outputFile = outputFile;
+            m_format = format;
+            m_circularBufferSizeInMB = circularBufferSizeInMB;
+            m_providers = new List<EventPipeProviderConfiguration>();
+        }
+
+        internal string OutputFile
+        {
+            get { return m_outputFile; }
+        }
+
+        internal EventPipeSerializationFormat Format
+        {
+            get { return m_format; }
+        }
+
+        internal uint CircularBufferSizeInMB
+        {
+            get { return m_circularBufferSizeInMB; }
+        }
+
+        internal EventPipeProviderConfiguration[] Providers
+        {
+            get { return m_providers.ToArray(); }
+        }
+
+        internal void EnableProvider(string providerName, ulong keywords, uint loggingLevel)
+        {
+            EnableProviderWithFilter(providerName, keywords, loggingLevel, null);
+        }
+
+        internal void EnableProviderWithFilter(string providerName, ulong keywords, uint loggingLevel, string? filterData)
+        {
+            m_providers.Add(new EventPipeProviderConfiguration(
+                providerName,
+                keywords,
+                loggingLevel,
+                filterData));
+        }
+
+        private void EnableProviderConfiguration(EventPipeProviderConfiguration providerConfig)
+        {
+            m_providers.Add(providerConfig);
+        }
+
+        internal void EnableProviderRange(EventPipeProviderConfiguration[] providerConfigs)
+        {
+            foreach (EventPipeProviderConfiguration config in providerConfigs)
+            {
+                EnableProviderConfiguration(config);
+            }
+        }
+
+        internal void SetProfilerSamplingRate(TimeSpan minTimeBetweenSamples)
+        {
+            if (minTimeBetweenSamples.Ticks <= 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(minTimeBetweenSamples));
+            }
+
+            m_minTimeBetweenSamples = minTimeBetweenSamples;
+        }
+    }
+
+    internal static class EventPipe
+    {
+        private static ulong s_sessionID = 0;
+
+        internal static void Enable(EventPipeConfiguration configuration)
+        {
+            if (configuration == null)
+            {
+                throw new ArgumentNullException(nameof(configuration));
+            }
+
+            if (configuration.Providers == null)
+            {
+                throw new ArgumentNullException(nameof(configuration.Providers));
+            }
+
+            EventPipeProviderConfiguration[] providers = configuration.Providers;
+
+            s_sessionID = EventPipeInternal.Enable(
+                configuration.OutputFile,
+                configuration.Format,
+                configuration.CircularBufferSizeInMB,
+                providers);
+        }
+
+        internal static void Disable()
+        {
+            EventPipeInternal.Disable(s_sessionID);
+        }
+    }
+
+    internal static partial class EventPipeInternal
+    {
+        private unsafe struct EventPipeProviderConfigurationNative
+        {
+            private char* m_pProviderName;
+            private ulong m_keywords;
+            private uint m_loggingLevel;
+            private char* m_pFilterData;
+
+            internal static void MarshalToNative(EventPipeProviderConfiguration managed, ref EventPipeProviderConfigurationNative native)
+            {
+                native.m_pProviderName = (char*)Marshal.StringToCoTaskMemUni(managed.ProviderName);
+                native.m_keywords = managed.Keywords;
+                native.m_loggingLevel = managed.LoggingLevel;
+                native.m_pFilterData = (char*)Marshal.StringToCoTaskMemUni(managed.FilterData);
+            }
+
+            internal void Release()
+            {
+                if (m_pProviderName != null)
+                {
+                    Marshal.FreeCoTaskMem((IntPtr)m_pProviderName);
+                }
+                if (m_pFilterData != null)
+                {
+                    Marshal.FreeCoTaskMem((IntPtr)m_pFilterData);
+                }
+            }
+        }
+
+        internal static unsafe ulong Enable(
+            string? outputFile,
+            EventPipeSerializationFormat format,
+            uint circularBufferSizeInMB,
+            EventPipeProviderConfiguration[] providers)
+        {
+            Span<EventPipeProviderConfigurationNative> providersNative = new Span<EventPipeProviderConfigurationNative>((void*)Marshal.AllocCoTaskMem(sizeof(EventPipeProviderConfigurationNative) * providers.Length), providers.Length);
+            providersNative.Clear();
+
+            try
+            {
+                for (int i = 0; i < providers.Length; i++)
+                {
+                    EventPipeProviderConfigurationNative.MarshalToNative(providers[i], ref providersNative[i]);
+                }
+
+                fixed (char* outputFilePath = outputFile)
+                fixed (EventPipeProviderConfigurationNative* providersNativePointer = providersNative)
+                {
+                    return Enable(outputFilePath, format, circularBufferSizeInMB, providersNativePointer, (uint)providersNative.Length);
+                }
+            }
+            finally
+            {
+                for (int i = 0; i < providers.Length; i++)
+                {
+                    providersNative[i].Release();
+                }
+
+                fixed (EventPipeProviderConfigurationNative* providersNativePointer = providersNative)
+                {
+                    Marshal.FreeCoTaskMem((IntPtr)providersNativePointer);
+                }
+            }
+        }
+    }
+}
+
+#endif // FEATURE_PERFTRACING

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventPipeEventDispatcher.cs

@@ -0,0 +1,226 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Win32.SafeHandles;
+
+namespace System.Diagnostics.Tracing
+{
+#if FEATURE_PERFTRACING
+    internal sealed class EventPipeEventDispatcher
+    {
+        internal sealed class EventListenerSubscription
+        {
+            internal EventKeywords MatchAnyKeywords { get; private set; }
+            internal EventLevel Level { get; private set; }
+
+            internal EventListenerSubscription(EventKeywords matchAnyKeywords, EventLevel level)
+            {
+                MatchAnyKeywords = matchAnyKeywords;
+                Level = level;
+            }
+        }
+
+        internal static readonly EventPipeEventDispatcher Instance = new EventPipeEventDispatcher();
+
+        private readonly IntPtr m_RuntimeProviderID;
+
+        private ulong m_sessionID = 0;
+        private DateTime m_syncTimeUtc;
+        private long m_syncTimeQPC;
+        private long m_timeQPCFrequency;
+
+        private bool m_stopDispatchTask;
+        private readonly EventPipeWaitHandle m_dispatchTaskWaitHandle = new EventPipeWaitHandle();
+        private Task? m_dispatchTask = null;
+        private readonly object m_dispatchControlLock = new object();
+        private readonly Dictionary<EventListener, EventListenerSubscription> m_subscriptions = new Dictionary<EventListener, EventListenerSubscription>();
+
+        private const uint DefaultEventListenerCircularMBSize = 10;
+
+        private EventPipeEventDispatcher()
+        {
+            // Get the ID of the runtime provider so that it can be used as a filter when processing events.
+            m_RuntimeProviderID = EventPipeInternal.GetProvider(NativeRuntimeEventSource.EventSourceName);
+            m_dispatchTaskWaitHandle.SafeWaitHandle = new SafeWaitHandle(IntPtr.Zero, false);
+        }
+
+        internal void SendCommand(EventListener eventListener, EventCommand command, bool enable, EventLevel level, EventKeywords matchAnyKeywords)
+        {
+            if (command == EventCommand.Update && enable)
+            {
+                lock (m_dispatchControlLock)
+                {
+                    // Add the new subscription.  This will overwrite an existing subscription for the listener if one exists.
+                    m_subscriptions[eventListener] = new EventListenerSubscription(matchAnyKeywords, level);
+
+                    // Commit the configuration change.
+                    CommitDispatchConfiguration();
+                }
+            }
+            else if (command == EventCommand.Update && !enable)
+            {
+                RemoveEventListener(eventListener);
+            }
+        }
+
+        internal void RemoveEventListener(EventListener listener)
+        {
+            lock (m_dispatchControlLock)
+            {
+                // Remove the event listener from the list of subscribers.
+                if (m_subscriptions.ContainsKey(listener))
+                {
+                    m_subscriptions.Remove(listener);
+                }
+
+                // Commit the configuration change.
+                CommitDispatchConfiguration();
+            }
+        }
+
+        private void CommitDispatchConfiguration()
+        {
+            Debug.Assert(Monitor.IsEntered(m_dispatchControlLock));
+
+            // Ensure that the dispatch task is stopped.
+            // This is a no-op if the task is already stopped.
+            StopDispatchTask();
+
+            // Stop tracing.
+            // This is a no-op if it's already disabled.
+            EventPipeInternal.Disable(m_sessionID);
+
+            // Check to see if tracing should be enabled.
+            if (m_subscriptions.Count <= 0)
+            {
+                return;
+            }
+
+            // Determine the keywords and level that should be used based on the set of enabled EventListeners.
+            EventKeywords aggregatedKeywords = EventKeywords.None;
+            EventLevel highestLevel = EventLevel.LogAlways;
+
+            foreach (EventListenerSubscription subscription in m_subscriptions.Values)
+            {
+                aggregatedKeywords |= subscription.MatchAnyKeywords;
+                highestLevel = (subscription.Level > highestLevel) ? subscription.Level : highestLevel;
+            }
+
+            // Enable the EventPipe session.
+            EventPipeProviderConfiguration[] providerConfiguration = new EventPipeProviderConfiguration[]
+            {
+                new EventPipeProviderConfiguration(NativeRuntimeEventSource.EventSourceName, (ulong)aggregatedKeywords, (uint)highestLevel, null)
+            };
+
+            m_sessionID = EventPipeInternal.Enable(null, EventPipeSerializationFormat.NetTrace, DefaultEventListenerCircularMBSize, providerConfiguration);
+            Debug.Assert(m_sessionID != 0);
+
+            // Get the session information that is required to properly dispatch events.
+            EventPipeSessionInfo sessionInfo;
+            unsafe
+            {
+                if (!EventPipeInternal.GetSessionInfo(m_sessionID, &sessionInfo))
+                {
+                    Debug.Fail("GetSessionInfo returned false.");
+                }
+            }
+
+            m_syncTimeUtc = DateTime.FromFileTimeUtc(sessionInfo.StartTimeAsUTCFileTime);
+            m_syncTimeQPC = sessionInfo.StartTimeStamp;
+            m_timeQPCFrequency = sessionInfo.TimeStampFrequency;
+
+            // Start the dispatch task.
+            StartDispatchTask();
+        }
+
+        private void StartDispatchTask()
+        {
+            Debug.Assert(Monitor.IsEntered(m_dispatchControlLock));
+
+            if (m_dispatchTask == null)
+            {
+                m_stopDispatchTask = false;
+                // Create a SafeWaitHandle that won't release the handle when done
+                m_dispatchTaskWaitHandle.SafeWaitHandle = new SafeWaitHandle(EventPipeInternal.GetWaitHandle(m_sessionID), false);
+
+                m_dispatchTask = Task.Factory.StartNew(DispatchEventsToEventListeners, CancellationToken.None, TaskCreationOptions.LongRunning, TaskScheduler.Default);
+            }
+        }
+
+        private void StopDispatchTask()
+        {
+            Debug.Assert(Monitor.IsEntered(m_dispatchControlLock));
+
+            if (m_dispatchTask != null)
+            {
+                m_stopDispatchTask = true;
+                Debug.Assert(!m_dispatchTaskWaitHandle.SafeWaitHandle.IsInvalid);
+                EventWaitHandle.Set(m_dispatchTaskWaitHandle.SafeWaitHandle);
+                m_dispatchTask.Wait();
+                m_dispatchTask = null;
+            }
+        }
+
+        private unsafe void DispatchEventsToEventListeners()
+        {
+            // Struct to fill with the call to GetNextEvent.
+            EventPipeEventInstanceData instanceData;
+
+            while (!m_stopDispatchTask)
+            {
+                bool eventsReceived = false;
+                // Get the next event.
+                while (!m_stopDispatchTask && EventPipeInternal.GetNextEvent(m_sessionID, &instanceData))
+                {
+                    eventsReceived = true;
+
+                    // Filter based on provider.
+                    if (instanceData.ProviderID == m_RuntimeProviderID)
+                    {
+                        // Dispatch the event.
+                        ReadOnlySpan<byte> payload = new ReadOnlySpan<byte>((void*)instanceData.Payload, (int)instanceData.PayloadLength);
+                        DateTime dateTimeStamp = TimeStampToDateTime(instanceData.TimeStamp);
+                        NativeRuntimeEventSource.Log.ProcessEvent(instanceData.EventID, instanceData.ThreadID, dateTimeStamp, instanceData.ActivityId, instanceData.ChildActivityId, payload);
+                    }
+                }
+
+                // Wait for more events.
+                if (!m_stopDispatchTask)
+                {
+                    if (!eventsReceived)
+                    {
+                        // Future TODO: this would make more sense to handle in EventPipeSession/EventPipe native code.
+                        Debug.Assert(!m_dispatchTaskWaitHandle.SafeWaitHandle.IsInvalid);
+                        m_dispatchTaskWaitHandle.WaitOne();
+                    }
+
+                    Thread.Sleep(10);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Converts a QueryPerformanceCounter (QPC) timestamp to a UTC DateTime.
+        /// </summary>
+        private DateTime TimeStampToDateTime(long timeStamp)
+        {
+            if (timeStamp == long.MaxValue)
+            {
+                return DateTime.MaxValue;
+            }
+
+            Debug.Assert((m_syncTimeUtc.Ticks != 0) && (m_syncTimeQPC != 0) && (m_timeQPCFrequency != 0));
+            long inTicks = (long)((timeStamp - m_syncTimeQPC) * 10000000.0 / m_timeQPCFrequency) + m_syncTimeUtc.Ticks;
+            if ((inTicks < 0) || (DateTime.MaxTicks < inTicks))
+            {
+                inTicks = DateTime.MaxTicks;
+            }
+
+            return new DateTime(inTicks, DateTimeKind.Utc);
+        }
+    }
+#endif // FEATURE_PERFTRACING
+}

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventPipeEventProvider.cs

@@ -0,0 +1,89 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Diagnostics.Tracing
+{
+    internal sealed class EventPipeEventProvider : IEventProvider
+    {
+        // The EventPipeProvider handle.
+        private IntPtr m_provHandle = IntPtr.Zero;
+
+        // Register an event provider.
+        unsafe uint IEventProvider.EventRegister(
+            EventSource eventSource,
+            Interop.Advapi32.EtwEnableCallback enableCallback,
+            void* callbackContext,
+            ref long registrationHandle)
+        {
+            uint returnStatus = 0;
+            m_provHandle = EventPipeInternal.CreateProvider(eventSource.Name, enableCallback);
+            if (m_provHandle != IntPtr.Zero)
+            {
+                // Fixed registration handle because a new EventPipeEventProvider
+                // will be created for each new EventSource.
+                registrationHandle = 1;
+            }
+            else
+            {
+                // Unable to create the provider.
+                returnStatus = 1;
+            }
+
+            return returnStatus;
+        }
+
+        // Unregister an event provider.
+        uint IEventProvider.EventUnregister(long registrationHandle)
+        {
+            EventPipeInternal.DeleteProvider(m_provHandle);
+            return 0;
+        }
+
+        // Write an event.
+        unsafe EventProvider.WriteEventErrorCode IEventProvider.EventWriteTransfer(
+            long registrationHandle,
+            in EventDescriptor eventDescriptor,
+            IntPtr eventHandle,
+            Guid* activityId,
+            Guid* relatedActivityId,
+            int userDataCount,
+            EventProvider.EventData* userData)
+        {
+            if (eventHandle != IntPtr.Zero)
+            {
+                if (userDataCount == 0)
+                {
+                    EventPipeInternal.WriteEventData(eventHandle, null, 0, activityId, relatedActivityId);
+                    return EventProvider.WriteEventErrorCode.NoError;
+                }
+
+                // If Channel == 11, this is a TraceLogging event.
+                // The first 3 descriptors contain event metadata that is emitted for ETW and should be discarded on EventPipe.
+                // EventPipe metadata is provided via the EventPipeEventProvider.DefineEventHandle.
+                if (eventDescriptor.Channel == 11)
+                {
+                    userData += 3;
+                    userDataCount -= 3;
+                    Debug.Assert(userDataCount >= 0);
+                }
+                EventPipeInternal.WriteEventData(eventHandle, userData, (uint)userDataCount, activityId, relatedActivityId);
+            }
+
+            return EventProvider.WriteEventErrorCode.NoError;
+        }
+
+        // Get or set the per-thread activity ID.
+        int IEventProvider.EventActivityIdControl(Interop.Advapi32.ActivityControl ControlCode, ref Guid ActivityId)
+        {
+            return EventPipeInternal.EventActivityIdControl((uint)ControlCode, ref ActivityId);
+        }
+
+        // Define an EventPipeEvent handle.
+        unsafe IntPtr IEventProvider.DefineEventHandle(uint eventID, string eventName, long keywords, uint eventVersion, uint level, byte* pMetadata, uint metadataLength)
+        {
+            IntPtr eventHandlePtr = EventPipeInternal.DefineEvent(m_provHandle, eventID, keywords, eventVersion, level, pMetadata, metadataLength);
+            return eventHandlePtr;
+        }
+    }
+}

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventPipeMetadataGenerator.cs

@@ -0,0 +1,412 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+using System.Reflection;
+using EventMetadata = System.Diagnostics.Tracing.EventSource.EventMetadata;
+
+namespace System.Diagnostics.Tracing
+{
+#if FEATURE_PERFTRACING
+    internal sealed class EventPipeMetadataGenerator
+    {
+        public static EventPipeMetadataGenerator Instance = new EventPipeMetadataGenerator();
+
+        private EventPipeMetadataGenerator() { }
+
+        public byte[]? GenerateEventMetadata(EventMetadata eventMetadata)
+        {
+            ParameterInfo[] parameters = eventMetadata.Parameters;
+            EventParameterInfo[] eventParams = new EventParameterInfo[parameters.Length];
+            for (int i = 0; i < parameters.Length; i++)
+            {
+                eventParams[i].SetInfo(parameters[i].Name!, parameters[i].ParameterType);
+            }
+
+            return GenerateMetadata(
+                eventMetadata.Descriptor.EventId,
+                eventMetadata.Name,
+                eventMetadata.Descriptor.Keywords,
+                eventMetadata.Descriptor.Level,
+                eventMetadata.Descriptor.Version,
+                eventParams);
+        }
+
+        public byte[]? GenerateEventMetadata(
+            int eventId,
+            string eventName,
+            EventKeywords keywords,
+            EventLevel level,
+            uint version,
+            TraceLoggingEventTypes eventTypes)
+        {
+            TraceLoggingTypeInfo[] typeInfos = eventTypes.typeInfos;
+            string[]? paramNames = eventTypes.paramNames;
+            EventParameterInfo[] eventParams = new EventParameterInfo[typeInfos.Length];
+            for (int i = 0; i < typeInfos.Length; i++)
+            {
+                string paramName = string.Empty;
+                if (paramNames != null)
+                {
+                    paramName = paramNames[i];
+                }
+                eventParams[i].SetInfo(paramName, typeInfos[i].DataType, typeInfos[i]);
+            }
+
+            return GenerateMetadata(eventId, eventName, (long)keywords, (uint)level, version, eventParams);
+        }
+
+        internal unsafe byte[]? GenerateMetadata(
+            int eventId,
+            string eventName,
+            long keywords,
+            uint level,
+            uint version,
+            EventParameterInfo[] parameters)
+        {
+            byte[]? metadata = null;
+            try
+            {
+                // eventID          : 4 bytes
+                // eventName        : (eventName.Length + 1) * 2 bytes
+                // keywords         : 8 bytes
+                // eventVersion     : 4 bytes
+                // level            : 4 bytes
+                // parameterCount   : 4 bytes
+                uint metadataLength = 24 + ((uint)eventName.Length + 1) * 2;
+                uint defaultMetadataLength = metadataLength;
+
+                // Check for an empty payload.
+                // Write<T> calls with no arguments by convention have a parameter of
+                // type NullTypeInfo which is serialized as nothing.
+                if ((parameters.Length == 1) && (parameters[0].ParameterType == typeof(EmptyStruct)))
+                {
+                    parameters = Array.Empty<EventParameterInfo>();
+                }
+
+                // Increase the metadataLength for parameters.
+                foreach (EventParameterInfo parameter in parameters)
+                {
+                    int pMetadataLength = parameter.GetMetadataLength();
+                    // The call above may return -1 which means we failed to get the metadata length.
+                    // We then return a default metadata blob (with parameterCount of 0) to prevent it from generating malformed metadata.
+                    if (pMetadataLength < 0)
+                    {
+                        parameters = Array.Empty<EventParameterInfo>();
+                        metadataLength = defaultMetadataLength;
+                        break;
+                    }
+                    metadataLength += (uint)pMetadataLength;
+                }
+
+                metadata = new byte[metadataLength];
+
+                // Write metadata: eventID, eventName, keywords, eventVersion, level, parameterCount, param1 type, param1 name...
+                fixed (byte* pMetadata = metadata)
+                {
+                    uint offset = 0;
+                    WriteToBuffer(pMetadata, metadataLength, ref offset, (uint)eventId);
+                    fixed (char* pEventName = eventName)
+                    {
+                        WriteToBuffer(pMetadata, metadataLength, ref offset, (byte*)pEventName, ((uint)eventName.Length + 1) * 2);
+                    }
+                    WriteToBuffer(pMetadata, metadataLength, ref offset, keywords);
+                    WriteToBuffer(pMetadata, metadataLength, ref offset, version);
+                    WriteToBuffer(pMetadata, metadataLength, ref offset, level);
+                    WriteToBuffer(pMetadata, metadataLength, ref offset, (uint)parameters.Length);
+                    foreach (EventParameterInfo parameter in parameters)
+                    {
+                        if (!parameter.GenerateMetadata(pMetadata, ref offset, metadataLength))
+                        {
+                            // If we fail to generate metadata for any parameter, we should return the "default" metadata without any parameters
+                            return GenerateMetadata(eventId, eventName, keywords, level, version, Array.Empty<EventParameterInfo>());
+                        }
+                    }
+                    Debug.Assert(metadataLength == offset);
+                }
+            }
+            catch
+            {
+                // If a failure occurs during metadata generation, make sure that we don't return
+                // malformed metadata.  Instead, return a null metadata blob.
+                // Consumers can either build in knowledge of the event or skip it entirely.
+                metadata = null;
+            }
+
+            return metadata;
+        }
+
+        // Copy src to buffer and modify the offset.
+        // Note: We know the buffer size ahead of time to make sure no buffer overflow.
+        internal static unsafe void WriteToBuffer(byte* buffer, uint bufferLength, ref uint offset, byte* src, uint srcLength)
+        {
+            Debug.Assert(bufferLength >= (offset + srcLength));
+            for (int i = 0; i < srcLength; i++)
+            {
+                *(byte*)(buffer + offset + i) = *(byte*)(src + i);
+            }
+            offset += srcLength;
+        }
+
+        // Copy uint value to buffer.
+        internal static unsafe void WriteToBuffer(byte* buffer, uint bufferLength, ref uint offset, uint value)
+        {
+            Debug.Assert(bufferLength >= (offset + 4));
+            *(uint*)(buffer + offset) = value;
+            offset += 4;
+        }
+
+        // Copy long value to buffer.
+        internal static unsafe void WriteToBuffer(byte* buffer, uint bufferLength, ref uint offset, long value)
+        {
+            Debug.Assert(bufferLength >= (offset + 8));
+            *(long*)(buffer + offset) = value;
+            offset += 8;
+        }
+
+        // Copy char value to buffer.
+        internal static unsafe void WriteToBuffer(byte* buffer, uint bufferLength, ref uint offset, char value)
+        {
+            Debug.Assert(bufferLength >= (offset + 2));
+            *(char*)(buffer + offset) = value;
+            offset += 2;
+        }
+    }
+
+    internal struct EventParameterInfo
+    {
+        internal string ParameterName;
+        internal Type ParameterType;
+        internal TraceLoggingTypeInfo? TypeInfo;
+
+        internal void SetInfo(string name, Type type, TraceLoggingTypeInfo? typeInfo = null)
+        {
+            ParameterName = name;
+            ParameterType = type;
+            TypeInfo = typeInfo;
+        }
+
+        internal unsafe bool GenerateMetadata(byte* pMetadataBlob, ref uint offset, uint blobSize)
+        {
+            TypeCode typeCode = GetTypeCodeExtended(ParameterType);
+            if (typeCode == TypeCode.Object)
+            {
+                // Each nested struct is serialized as:
+                //     TypeCode.Object              : 4 bytes
+                //     Number of properties         : 4 bytes
+                //     Property description 0...N
+                //     Nested struct property name  : NULL-terminated string.
+                EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, (uint)TypeCode.Object);
+
+                if (!(TypeInfo is InvokeTypeInfo invokeTypeInfo))
+                {
+                    return false;
+                }
+
+                // Get the set of properties to be serialized.
+                PropertyAnalysis[]? properties = invokeTypeInfo.properties;
+                if (properties != null)
+                {
+                    // Write the count of serializable properties.
+                    EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, (uint)properties.Length);
+
+                    foreach (PropertyAnalysis prop in properties)
+                    {
+                        if (!GenerateMetadataForProperty(prop, pMetadataBlob, ref offset, blobSize))
+                        {
+                            return false;
+                        }
+                    }
+                }
+                else
+                {
+                    // This struct has zero serializable properties so we just write the property count.
+                    EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, (uint)0);
+                }
+
+                // Top-level structs don't have a property name, but for simplicity we write a NULL-char to represent the name.
+                EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, '\0');
+            }
+            else
+            {
+                // Write parameter type.
+                EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, (uint)typeCode);
+
+                // Write parameter name.
+                fixed (char* pParameterName = ParameterName)
+                {
+                    EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, (byte*)pParameterName, ((uint)ParameterName.Length + 1) * 2);
+                }
+            }
+            return true;
+        }
+
+        private static unsafe bool GenerateMetadataForProperty(PropertyAnalysis property, byte* pMetadataBlob, ref uint offset, uint blobSize)
+        {
+            Debug.Assert(property != null);
+            Debug.Assert(pMetadataBlob != null);
+
+            // Check if this property is a nested struct.
+            if (property.typeInfo is InvokeTypeInfo invokeTypeInfo)
+            {
+                // Each nested struct is serialized as:
+                //     TypeCode.Object              : 4 bytes
+                //     Number of properties         : 4 bytes
+                //     Property description 0...N
+                //     Nested struct property name  : NULL-terminated string.
+                EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, (uint)TypeCode.Object);
+
+                // Get the set of properties to be serialized.
+                PropertyAnalysis[]? properties = invokeTypeInfo.properties;
+                if (properties != null)
+                {
+                    // Write the count of serializable properties.
+                    EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, (uint)properties.Length);
+
+                    foreach (PropertyAnalysis prop in properties)
+                    {
+                        if (!GenerateMetadataForProperty(prop, pMetadataBlob, ref offset, blobSize))
+                        {
+                            return false;
+                        }
+                    }
+                }
+                else
+                {
+                    // This struct has zero serializable properties so we just write the property count.
+                    EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, (uint)0);
+                }
+
+                // Write the property name.
+                fixed (char* pPropertyName = property.name)
+                {
+                    EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, (byte*)pPropertyName, ((uint)property.name.Length + 1) * 2);
+                }
+            }
+            else
+            {
+                // Each primitive type is serialized as:
+                //     TypeCode : 4 bytes
+                //     PropertyName : NULL-terminated string
+                TypeCode typeCode = GetTypeCodeExtended(property.typeInfo.DataType);
+
+                // EventPipe does not support this type.  Throw, which will cause no metadata to be registered for this event.
+                if (typeCode == TypeCode.Object)
+                {
+                    return false;
+                }
+
+                // Write the type code.
+                EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, (uint)typeCode);
+
+                // Write the property name.
+                fixed (char* pPropertyName = property.name)
+                {
+                    EventPipeMetadataGenerator.WriteToBuffer(pMetadataBlob, blobSize, ref offset, (byte*)pPropertyName, ((uint)property.name.Length + 1) * 2);
+                }
+            }
+            return true;
+        }
+
+        internal int GetMetadataLength()
+        {
+            int ret = 0;
+
+            TypeCode typeCode = GetTypeCodeExtended(ParameterType);
+            if (typeCode == TypeCode.Object)
+            {
+                if (!(TypeInfo is InvokeTypeInfo typeInfo))
+                {
+                    return -1;
+                }
+
+                // Each nested struct is serialized as:
+                //     TypeCode.Object      : 4 bytes
+                //     Number of properties : 4 bytes
+                //     Property description 0...N
+                //     Nested struct property name  : NULL-terminated string.
+                ret += sizeof(uint)  // TypeCode
+                     + sizeof(uint); // Property count
+
+                // Get the set of properties to be serialized.
+                PropertyAnalysis[]? properties = typeInfo.properties;
+                if (properties != null)
+                {
+                    foreach (PropertyAnalysis prop in properties)
+                    {
+                        ret += (int)GetMetadataLengthForProperty(prop);
+                    }
+                }
+
+                // For simplicity when writing a reader, we write a NULL char
+                // after the metadata for a top-level struct (for its name) so that
+                // readers don't have do special case the outer-most struct.
+                ret += sizeof(char);
+            }
+            else
+            {
+                ret += (int)(sizeof(uint) + ((ParameterName.Length + 1) * 2));
+            }
+
+            return ret;
+        }
+
+        private static uint GetMetadataLengthForProperty(PropertyAnalysis property)
+        {
+            Debug.Assert(property != null);
+
+            uint ret = 0;
+
+            // Check if this property is a nested struct.
+            if (property.typeInfo is InvokeTypeInfo invokeTypeInfo)
+            {
+                // Each nested struct is serialized as:
+                //     TypeCode.Object      : 4 bytes
+                //     Number of properties : 4 bytes
+                //     Property description 0...N
+                //     Nested struct property name  : NULL-terminated string.
+                ret += sizeof(uint)  // TypeCode
+                     + sizeof(uint); // Property count
+
+                // Get the set of properties to be serialized.
+                PropertyAnalysis[]? properties = invokeTypeInfo.properties;
+                if (properties != null)
+                {
+                    foreach (PropertyAnalysis prop in properties)
+                    {
+                        ret += GetMetadataLengthForProperty(prop);
+                    }
+                }
+
+                // Add the size of the property name.
+                ret += (uint)((property.name.Length + 1) * 2);
+            }
+            else
+            {
+                ret += (uint)(sizeof(uint) + ((property.name.Length + 1) * 2));
+            }
+
+            return ret;
+        }
+
+        private static TypeCode GetTypeCodeExtended(Type parameterType)
+        {
+            // Guid is not part of TypeCode, we decided to use 17 to represent it, as it's the "free slot"
+            // see https://github.com/dotnet/coreclr/issues/16105#issuecomment-361749750 for more
+            const TypeCode GuidTypeCode = (TypeCode)17;
+
+            if (parameterType == typeof(Guid)) // Guid is not a part of TypeCode enum
+                return GuidTypeCode;
+
+            // IntPtr and UIntPtr are converted to their non-pointer types.
+            if (parameterType == typeof(IntPtr))
+                return IntPtr.Size == 4 ? TypeCode.Int32 : TypeCode.Int64;
+
+            if (parameterType == typeof(UIntPtr))
+                return UIntPtr.Size == 4 ? TypeCode.UInt32 : TypeCode.UInt64;
+
+            return Type.GetTypeCode(parameterType);
+        }
+    }
+
+#endif // FEATURE_PERFTRACING
+}

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventPipePayloadDecoder.cs

@@ -0,0 +1,149 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+using System.Buffers.Binary;
+using System.Reflection;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace System.Diagnostics.Tracing
+{
+#if FEATURE_PERFTRACING
+    internal static class EventPipePayloadDecoder
+    {
+        /// <summary>
+        /// Given the metadata for an event and an event payload, decode and deserialize the event payload.
+        /// </summary>
+        internal static object[] DecodePayload(ref EventSource.EventMetadata metadata, ReadOnlySpan<byte> payload)
+        {
+            ParameterInfo[] parameters = metadata.Parameters;
+            object[] decodedFields = new object[parameters.Length];
+            for (int i = 0; i < parameters.Length; i++)
+            {
+                // It is possible that an older version of the event was emitted.
+                // If this happens, the payload might be missing arguments at the end.
+                // We can just leave these unset.
+                if (payload.Length <= 0)
+                {
+                    break;
+                }
+
+                Type parameterType = parameters[i].ParameterType;
+                if (parameterType == typeof(IntPtr))
+                {
+                    if (IntPtr.Size == 8)
+                    {
+                        decodedFields[i] = (IntPtr)BinaryPrimitives.ReadInt64LittleEndian(payload);
+                    }
+                    else
+                    {
+                        decodedFields[i] = (IntPtr)BinaryPrimitives.ReadInt32LittleEndian(payload);
+                    }
+                    payload = payload.Slice(IntPtr.Size);
+                }
+                else if (parameterType == typeof(int))
+                {
+                    decodedFields[i] = BinaryPrimitives.ReadInt32LittleEndian(payload);
+                    payload = payload.Slice(sizeof(int));
+                }
+                else if (parameterType == typeof(uint))
+                {
+                    decodedFields[i] = BinaryPrimitives.ReadUInt32LittleEndian(payload);
+                    payload = payload.Slice(sizeof(uint));
+                }
+                else if (parameterType == typeof(long))
+                {
+                    decodedFields[i] = BinaryPrimitives.ReadInt64LittleEndian(payload);
+                    payload = payload.Slice(sizeof(long));
+                }
+                else if (parameterType == typeof(ulong))
+                {
+                    decodedFields[i] = BinaryPrimitives.ReadUInt64LittleEndian(payload);
+                    payload = payload.Slice(sizeof(ulong));
+                }
+                else if (parameterType == typeof(byte))
+                {
+                    decodedFields[i] = MemoryMarshal.Read<byte>(payload);
+                    payload = payload.Slice(sizeof(byte));
+                }
+                else if (parameterType == typeof(sbyte))
+                {
+                    decodedFields[i] = MemoryMarshal.Read<sbyte>(payload);
+                    payload = payload.Slice(sizeof(sbyte));
+                }
+                else if (parameterType == typeof(short))
+                {
+                    decodedFields[i] = BinaryPrimitives.ReadInt16LittleEndian(payload);
+                    payload = payload.Slice(sizeof(short));
+                }
+                else if (parameterType == typeof(ushort))
+                {
+                    decodedFields[i] = BinaryPrimitives.ReadUInt16LittleEndian(payload);
+                    payload = payload.Slice(sizeof(ushort));
+                }
+                else if (parameterType == typeof(float))
+                {
+                    decodedFields[i] = BitConverter.Int32BitsToSingle(BinaryPrimitives.ReadInt32LittleEndian(payload));
+                    payload = payload.Slice(sizeof(float));
+                }
+                else if (parameterType == typeof(double))
+                {
+                    decodedFields[i] = BitConverter.Int64BitsToDouble(BinaryPrimitives.ReadInt64LittleEndian(payload));
+                    payload = payload.Slice(sizeof(double));
+                }
+                else if (parameterType == typeof(bool))
+                {
+                    // The manifest defines a bool as a 32bit type (WIN32 BOOL), not 1 bit as CLR Does.
+                    decodedFields[i] = (BinaryPrimitives.ReadInt32LittleEndian(payload) == 1);
+                    payload = payload.Slice(sizeof(int));
+                }
+                else if (parameterType == typeof(Guid))
+                {
+                    const int sizeOfGuid = 16;
+                    decodedFields[i] = new Guid(payload.Slice(0, sizeOfGuid));
+                    payload = payload.Slice(sizeOfGuid);
+                }
+                else if (parameterType == typeof(char))
+                {
+                    decodedFields[i] = (char)BinaryPrimitives.ReadUInt16LittleEndian(payload);
+                    payload = payload.Slice(sizeof(char));
+                }
+                else if (parameterType == typeof(string))
+                {
+                    // Try to find null terminator (0x00) from the byte span
+                    // NOTE: we do this by hand instead of using IndexOf because payload may be unaligned due to
+                    // mixture of different types being stored in the same buffer. (see eventpipe.cpp:CopyData)
+                    int byteCount = -1;
+                    for (int j = 1; j < payload.Length; j += 2)
+                    {
+                        if (payload[j - 1] == (byte)(0) && payload[j] == (byte)(0))
+                        {
+                            byteCount = j + 1;
+                            break;
+                        }
+                    }
+
+                    ReadOnlySpan<char> charPayload;
+                    if (byteCount < 0)
+                    {
+                        charPayload = MemoryMarshal.Cast<byte, char>(payload);
+                        payload = default;
+                    }
+                    else
+                    {
+                        charPayload = MemoryMarshal.Cast<byte, char>(payload.Slice(0, byteCount - 2));
+                        payload = payload.Slice(byteCount);
+                    }
+                    decodedFields[i] = BitConverter.IsLittleEndian ? new string(charPayload) : Encoding.Unicode.GetString(MemoryMarshal.Cast<char, byte>(charPayload));
+                }
+                else
+                {
+                    Debug.Fail("Unsupported type encountered.");
+                }
+            }
+
+            return decodedFields;
+        }
+    }
+#endif // FEATURE_PERFTRACING
+}

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventProvider.cs

@@ -13,7 +13,7 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.Numerics;
 using System.Runtime.InteropServices;
-#if CORECLR && TARGET_WINDOWS
+#if (CORECLR || MONO) && TARGET_WINDOWS
 using Internal.Win32;
 #endif
 #if ES_BUILD_AGAINST_DOTNET_V35
@@ -288,10 +288,8 @@ namespace System.Diagnostics.Tracing
                             filterData = null;
 
                         // read filter data only when a session is being *added*
-                        byte[]? data;
-                        int keyIndex;
                         if (bEnabling &&
-                            GetDataFromController(etwSessionId, filterData, out command, out data, out keyIndex))
+                            GetDataFromController(etwSessionId, filterData, out command, out byte[]? data, out int keyIndex))
                         {
                             args = new Dictionary<string, string?>(4);
                             // data can be null if the filterArgs had a very large size which failed our sanity check
@@ -469,42 +467,59 @@ namespace System.Diagnostics.Tracing
             // does not have this issue.
 #if (TARGET_WINDOWS && (ES_SESSION_INFO || !ES_BUILD_STANDALONE))
             int buffSize = 256;     // An initial guess that probably works most of the time.
-            byte* buffer;
-            while (true)
+            byte* stackSpace = stackalloc byte[buffSize];
+            byte* buffer = stackSpace;
+            try
             {
-                byte* space = stackalloc byte[buffSize];
-                buffer = space;
-                int hr = 0;
-
-                fixed (Guid* provider = &m_providerId)
+                while (true)
                 {
-                    hr = Interop.Advapi32.EnumerateTraceGuidsEx(Interop.Advapi32.TRACE_QUERY_INFO_CLASS.TraceGuidQueryInfo,
-                        provider, sizeof(Guid), buffer, buffSize, out buffSize);
+                    int hr = 0;
+
+                    fixed (Guid* provider = &m_providerId)
+                    {
+                        hr = Interop.Advapi32.EnumerateTraceGuidsEx(Interop.Advapi32.TRACE_QUERY_INFO_CLASS.TraceGuidQueryInfo,
+                            provider, sizeof(Guid), buffer, buffSize, out buffSize);
+                    }
+                    if (hr == 0)
+                        break;
+                    if (hr != Interop.Errors.ERROR_INSUFFICIENT_BUFFER)
+                        return;
+
+                    if (buffer != stackSpace)
+                    {
+                        byte* toFree = buffer;
+                        buffer = null;
+                        Marshal.FreeHGlobal((IntPtr)toFree);
+                    }
+                    buffer = (byte*)Marshal.AllocHGlobal(buffSize);
+                }
+
+                var providerInfos = (Interop.Advapi32.TRACE_GUID_INFO*)buffer;
+                var providerInstance = (Interop.Advapi32.TRACE_PROVIDER_INSTANCE_INFO*)&providerInfos[1];
+                int processId = unchecked((int)Interop.Kernel32.GetCurrentProcessId());
+                // iterate over the instances of the EventProvider in all processes
+                for (int i = 0; i < providerInfos->InstanceCount; i++)
+                {
+                    if (providerInstance->Pid == processId)
+                    {
+                        var enabledInfos = (Interop.Advapi32.TRACE_ENABLE_INFO*)&providerInstance[1];
+                        // iterate over the list of active ETW sessions "listening" to the current provider
+                        for (int j = 0; j < providerInstance->EnableCount; j++)
+                            action(enabledInfos[j].LoggerId, enabledInfos[j].MatchAllKeyword, ref sessionList);
+                    }
+                    if (providerInstance->NextOffset == 0)
+                        break;
+                    Debug.Assert(0 <= providerInstance->NextOffset && providerInstance->NextOffset < buffSize);
+                    byte* structBase = (byte*)providerInstance;
+                    providerInstance = (Interop.Advapi32.TRACE_PROVIDER_INSTANCE_INFO*)&structBase[providerInstance->NextOffset];
                 }
-                if (hr == 0)
-                    break;
-                if (hr != Interop.Errors.ERROR_INSUFFICIENT_BUFFER)
-                    return;
             }
-
-            var providerInfos = (Interop.Advapi32.TRACE_GUID_INFO*)buffer;
-            var providerInstance = (Interop.Advapi32.TRACE_PROVIDER_INSTANCE_INFO*)&providerInfos[1];
-            int processId = unchecked((int)Interop.Kernel32.GetCurrentProcessId());
-            // iterate over the instances of the EventProvider in all processes
-            for (int i = 0; i < providerInfos->InstanceCount; i++)
+            finally
             {
-                if (providerInstance->Pid == processId)
+                if (buffer != null && buffer != stackSpace)
                 {
-                    var enabledInfos = (Interop.Advapi32.TRACE_ENABLE_INFO*)&providerInstance[1];
-                    // iterate over the list of active ETW sessions "listening" to the current provider
-                    for (int j = 0; j < providerInstance->EnableCount; j++)
-                        action(enabledInfos[j].LoggerId, enabledInfos[j].MatchAllKeyword, ref sessionList);
+                    Marshal.FreeHGlobal((IntPtr)buffer);
                 }
-                if (providerInstance->NextOffset == 0)
-                    break;
-                Debug.Assert(0 <= providerInstance->NextOffset && providerInstance->NextOffset < buffSize);
-                byte* structBase = (byte*)providerInstance;
-                providerInstance = (Interop.Advapi32.TRACE_PROVIDER_INSTANCE_INFO*)&structBase[providerInstance->NextOffset];
             }
 #else
 #if !ES_BUILD_PCL && TARGET_WINDOWS  // TODO command arguments don't work on PCL builds...

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventSource.cs

@@ -649,10 +649,8 @@ namespace System.Diagnostics.Tracing
         {
             m_config = ValidateSettings(settings);
 
-            Guid eventSourceGuid;
-            string? eventSourceName;
 
-            GetMetadata(out eventSourceGuid, out eventSourceName, out _, out _);
+            GetMetadata(out Guid eventSourceGuid, out string? eventSourceName, out _, out _);
 
             if (eventSourceGuid.Equals(Guid.Empty) || eventSourceName == null)
             {
@@ -1373,28 +1371,29 @@ namespace System.Diagnostics.Tracing
             int dataCount,
             IntPtr data)
         {
+#if FEATURE_MANAGED_ETW || FEATURE_PERFTRACING
+            bool allAreNull = true;
 #if FEATURE_MANAGED_ETW
-            if (m_etwProvider == null)
+            allAreNull &= (m_etwProvider == null);
+            if (m_etwProvider != null
+                && !m_etwProvider.WriteEventRaw(ref eventDescriptor, eventHandle, activityID, relatedActivityID, dataCount, data))
             {
                 ThrowEventSourceException(eventName);
             }
-            else
-            {
-                if (!m_etwProvider.WriteEventRaw(ref eventDescriptor, eventHandle, activityID, relatedActivityID, dataCount, data))
-                    ThrowEventSourceException(eventName);
-            }
 #endif // FEATURE_MANAGED_ETW
 #if FEATURE_PERFTRACING
-            if (m_eventPipeProvider == null)
+            allAreNull &= (m_eventPipeProvider == null);
+            if (m_eventPipeProvider != null
+                && !m_eventPipeProvider.WriteEventRaw(ref eventDescriptor, eventHandle, activityID, relatedActivityID, dataCount, data))
             {
                 ThrowEventSourceException(eventName);
             }
-            else
-            {
-                if (!m_eventPipeProvider.WriteEventRaw(ref eventDescriptor, eventHandle, activityID, relatedActivityID, dataCount, data))
-                    ThrowEventSourceException(eventName);
-            }
 #endif // FEATURE_PERFTRACING
+            if (allAreNull)
+            {
+                ThrowEventSourceException(eventName);
+            }
+#endif // FEATURE_MANAGED_ETW || FEATURE_PERFTRACING
         }
 
         // FrameworkEventSource is on the startup path for the framework, so we have this internal overload that it can use
@@ -2150,49 +2149,95 @@ namespace System.Diagnostics.Tracing
             }
         }
 
-        private unsafe void WriteEventString(EventLevel level, long keywords, string msgString)
+        // WriteEventString is used for logging an error message (or similar) to
+        // ETW and EventPipe providers. It is not a general purpose API, it will
+        // log the message with Level=LogAlways and Keywords=All to make sure whoever
+        // is listening gets the message.
+        private unsafe void WriteEventString(string msgString)
         {
+#if FEATURE_MANAGED_ETW || FEATURE_PERFTRACING
+            bool allAreNull = true;
 #if FEATURE_MANAGED_ETW
-            if (m_etwProvider != null)
+            allAreNull &= (m_etwProvider == null);
+#endif // FEATURE_MANAGED_ETW
+#if FEATURE_PERFTRACING
+            allAreNull &= (m_eventPipeProvider == null);
+#endif // FEATURE_PERFTRACING
+            if (allAreNull)
             {
-                const string EventName = "EventSourceMessage";
-                if (SelfDescribingEvents)
-                {
-                    EventSourceOptions opt = new EventSourceOptions
-                    {
-                        Keywords = (EventKeywords)unchecked(keywords),
-                        Level = level
-                    };
-                    var msg = new { message = msgString };
-                    var tlet = new TraceLoggingEventTypes(EventName, EventTags.None, new Type[] { msg.GetType() });
-                    WriteMultiMergeInner(EventName, ref opt, tlet, null, null, msg);
-                }
-                else
-                {
-                    // We want the name of the provider to show up so if we don't have a manifest we create
-                    // on that at least has the provider name (I don't define any events).
-                    if (m_rawManifest == null && m_outOfBandMessageCount == 1)
-                    {
-                        ManifestBuilder manifestBuilder = new ManifestBuilder(Name, Guid, Name, null, EventManifestOptions.None);
-                        manifestBuilder.StartEvent(EventName, new EventAttribute(0) { Level = EventLevel.LogAlways, Task = (EventTask)0xFFFE });
-                        manifestBuilder.AddEventParameter(typeof(string), "message");
-                        manifestBuilder.EndEvent();
-                        SendManifest(manifestBuilder.CreateManifest());
-                    }
+                return;
+            }
 
-                    // We use this low level routine to bypass the enabled checking, since the eventSource itself is only partially inited.
-                    fixed (char* msgStringPtr = msgString)
+            EventLevel level = EventLevel.LogAlways;
+            long keywords = -1;
+            const string EventName = "EventSourceMessage";
+            if (SelfDescribingEvents)
+            {
+                EventSourceOptions opt = new EventSourceOptions
+                {
+                    Keywords = (EventKeywords)unchecked(keywords),
+                    Level = level
+                };
+                var msg = new { message = msgString };
+                var tlet = new TraceLoggingEventTypes(EventName, EventTags.None, new Type[] { msg.GetType() });
+                WriteMultiMergeInner(EventName, ref opt, tlet, null, null, msg);
+            }
+            else
+            {
+                // We want the name of the provider to show up so if we don't have a manifest we create
+                // on that at least has the provider name (I don't define any events).
+                if (m_rawManifest == null && m_outOfBandMessageCount == 1)
+                {
+                    ManifestBuilder manifestBuilder = new ManifestBuilder(Name, Guid, Name, null, EventManifestOptions.None);
+                    manifestBuilder.StartEvent(EventName, new EventAttribute(0) { Level = level, Task = (EventTask)0xFFFE });
+                    manifestBuilder.AddEventParameter(typeof(string), "message");
+                    manifestBuilder.EndEvent();
+                    SendManifest(manifestBuilder.CreateManifest());
+                }
+
+                // We use this low level routine to bypass the enabled checking, since the eventSource itself is only partially inited.
+                fixed (char* msgStringPtr = msgString)
+                {
+                    EventDescriptor descr = new EventDescriptor(0, 0, 0, (byte)level, 0, 0, keywords);
+                    EventProvider.EventData data = default;
+                    data.Ptr = (ulong)msgStringPtr;
+                    data.Size = (uint)(2 * (msgString.Length + 1));
+                    data.Reserved = 0;
+#if FEATURE_MANAGED_ETW
+                    if (m_etwProvider != null)
                     {
-                        EventDescriptor descr = new EventDescriptor(0, 0, 0, (byte)level, 0, 0, keywords);
-                        EventProvider.EventData data = default;
-                        data.Ptr = (ulong)msgStringPtr;
-                        data.Size = (uint)(2 * (msgString.Length + 1));
-                        data.Reserved = 0;
                         m_etwProvider.WriteEvent(ref descr, IntPtr.Zero, null, null, 1, (IntPtr)((void*)&data));
                     }
+#endif // FEATURE_MANAGED_ETW
+#if FEATURE_PERFTRACING
+                    if (m_eventPipeProvider != null)
+                    {
+                        if (m_writeEventStringEventHandle == IntPtr.Zero)
+                        {
+                            lock (m_createEventLock)
+                            {
+                                if (m_writeEventStringEventHandle == IntPtr.Zero)
+                                {
+                                    string eventName = "EventSourceMessage";
+                                    EventParameterInfo paramInfo = default(EventParameterInfo);
+                                    paramInfo.SetInfo("message", typeof(string));
+                                    byte[]? metadata = EventPipeMetadataGenerator.Instance.GenerateMetadata(0, eventName, keywords, (uint)level, 0, new EventParameterInfo[] { paramInfo });
+                                    uint metadataLength = (metadata != null) ? (uint)metadata.Length : 0;
+
+                                    fixed (byte* pMetadata = metadata)
+                                    {
+                                        m_writeEventStringEventHandle = m_eventPipeProvider.m_eventProvider.DefineEventHandle(0, eventName, keywords, 0, (uint)level, pMetadata, metadataLength);
+                                    }
+                                }
+                            }
+                        }
+
+                        m_eventPipeProvider.WriteEvent(ref descr, m_writeEventStringEventHandle, null, null, 1, (IntPtr)((void*)&data));
+                    }
+#endif // FEATURE_PERFTRACING
                 }
             }
-#endif // FEATURE_MANAGED_ETW
+#endif // FEATURE_MANAGED_ETW || FEATURE_PERFTRACING
         }
 
         /// <summary>
@@ -2871,13 +2916,10 @@ namespace System.Diagnostics.Tracing
             if (m_eventData == null)
             {
                 Guid eventSourceGuid = Guid.Empty;
-                string? eventSourceName = null;
-                EventMetadata[]? eventData = null;
-                byte[]? manifest = null;
 
                 // Try the GetMetadata provided by the ILTransform in ProjectN. The default sets all to null, and in that case we fall back
                 // to the reflection approach.
-                GetMetadata(out eventSourceGuid, out eventSourceName, out eventData, out manifest);
+                GetMetadata(out eventSourceGuid, out string? eventSourceName, out EventMetadata[]? eventData, out byte[]? manifest);
 
                 if (eventSourceGuid.Equals(Guid.Empty) || eventSourceName == null || eventData == null || manifest == null)
                 {
@@ -3808,7 +3850,7 @@ namespace System.Diagnostics.Tracing
                     msg = "Reached message limit.   End of EventSource error messages.";
                 }
 
-                WriteEventString(EventLevel.LogAlways, -1, msg);
+                WriteEventString(msg);
                 WriteStringToAllListeners("EventSourceMessage", msg);
             }
             catch { }      // If we fail during last chance logging, well, we have to give up....
@@ -3865,6 +3907,8 @@ namespace System.Diagnostics.Tracing
         private volatile OverideEventProvider m_etwProvider = null!;   // This hooks up ETW commands to our 'OnEventCommand' callback
 #endif
 #if FEATURE_PERFTRACING
+        private object m_createEventLock = new object();
+        private IntPtr m_writeEventStringEventHandle = IntPtr.Zero;
         private volatile OverideEventProvider m_eventPipeProvider = null!;
 #endif
         private bool m_completelyInited;                // The EventSource constructor has returned without exception.
@@ -5551,8 +5595,7 @@ namespace System.Diagnostics.Tracing
             if (channelTab.Count == MaxCountChannels)
                 ManifestError(SR.EventSource_MaxChannelExceeded);
 
-            ChannelInfo? info;
-            if (!channelTab.TryGetValue((int)channel, out info))
+            if (!channelTab.TryGetValue((int)channel, out ChannelInfo? info))
             {
                 // If we were not given an explicit channel, allocate one.
                 if (channelKeyword != 0)
@@ -5876,8 +5919,7 @@ namespace System.Diagnostics.Tracing
 #if FEATURE_MANAGED_ETW_CHANNELS
         private string? GetChannelName(EventChannel channel, string eventName, string? eventMessage)
         {
-            ChannelInfo? info = null;
-            if (channelTab == null || !channelTab.TryGetValue((int)channel, out info))
+            if (channelTab == null || !channelTab.TryGetValue((int)channel, out ChannelInfo? info))
             {
                 if (channel < EventChannel.Admin) // || channel > EventChannel.Debug)
                     ManifestError(SR.Format(SR.EventSource_UndefinedChannel, channel, eventName));
@@ -5909,9 +5951,8 @@ namespace System.Diagnostics.Tracing
             if (task == EventTask.None)
                 return "";
 
-            string? ret;
             taskTab ??= new Dictionary<int, string>();
-            if (!taskTab.TryGetValue((int)task, out ret))
+            if (!taskTab.TryGetValue((int)task, out string? ret))
                 ret = taskTab[(int)task] = eventName;
             return ret;
         }
@@ -5944,8 +5985,7 @@ namespace System.Diagnostics.Tracing
                     return "win:Receive";
             }
 
-            string? ret;
-            if (opcodeTab == null || !opcodeTab.TryGetValue((int)opcode, out ret))
+            if (opcodeTab == null || !opcodeTab.TryGetValue((int)opcode, out string? ret))
             {
                 ManifestError(SR.Format(SR.EventSource_UndefinedOpcode, opcode, eventName), true);
                 ret = null;
@@ -6052,7 +6092,6 @@ namespace System.Diagnostics.Tracing
         {
             StringBuilder? stringBuilder = null;        // We lazily create this
             int writtenSoFar = 0;
-            int chIdx = -1;
             for (int i = 0; ;)
             {
                 if (i >= eventMessage.Length)
@@ -6063,6 +6102,7 @@ namespace System.Diagnostics.Tracing
                     return stringBuilder.ToString();
                 }
 
+                int chIdx;
                 if (eventMessage[i] == '%')
                 {
                     // handle format message escaping character '%' by escaping it
@@ -6125,8 +6165,7 @@ namespace System.Diagnostics.Tracing
 
         private int TranslateIndexToManifestConvention(int idx, string evtName)
         {
-            List<int>? byteArrArgIndices;
-            if (perEventByteArrayArgIndices.TryGetValue(evtName, out byteArrArgIndices))
+            if (perEventByteArrayArgIndices.TryGetValue(evtName, out List<int>? byteArrArgIndices))
             {
                 foreach (int byArrIdx in byteArrArgIndices)
                 {

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/NativeRuntimeEventSource.cs

@@ -0,0 +1,49 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Diagnostics.Tracing
+{
+    /// <summary>
+    /// NativeRuntimeEventSource is an EventSource that represents the ETW/EventPipe events emitted by the native runtime.
+    /// Most of NativeRuntimeEventSource is auto-generated by scripts/genRuntimeEventSources.py based on the contents of the Microsoft-Windows-DotNETRuntime provider.
+    /// </summary>
+    [EventSource(Guid = "5E5BB766-BBFC-5662-0548-1D44FAD9BB56", Name = "Microsoft-Windows-DotNETRuntime")]
+    internal sealed partial class NativeRuntimeEventSource : EventSource
+    {
+        internal const string EventSourceName = "Microsoft-Windows-DotNETRuntime";
+        internal static NativeRuntimeEventSource Log = new NativeRuntimeEventSource();
+
+        // The NativeRuntimeEventSource GUID is {5e5bb766-bbfc-5662-0548-1d44fad9bb56}
+        private NativeRuntimeEventSource() : base(new Guid(0x5e5bb766, 0xbbfc, 0x5662, 0x05, 0x48, 0x1d, 0x44, 0xfa, 0xd9, 0xbb, 0x56), EventSourceName) { }
+
+        /// <summary>
+        /// Dispatch a single event with the specified event ID and payload.
+        /// </summary>
+        /// <param name="eventID">The eventID corresponding to the event as defined in the auto-generated portion of the NativeRuntimeEventSource class.</param>
+        /// <param name="osThreadID">The thread ID of the operating system thread.</param>
+        /// <param name="timeStamp">The current timestamp.</param>
+        /// <param name="activityId">The ID of the current activity.</param>
+        /// <param name="childActivityId">The ID of the current child activity.</param>
+        /// <param name="payload">A span pointing to the data payload for the event.</param>
+        [NonEvent]
+        internal unsafe void ProcessEvent(uint eventID, uint osThreadID, DateTime timeStamp, Guid activityId, Guid childActivityId, ReadOnlySpan<byte> payload)
+        {
+            // Make sure the eventID is valid.
+            if (eventID >= m_eventData!.Length)
+            {
+                return;
+            }
+
+            // Decode the payload.
+            object[] decodedPayloadFields = EventPipePayloadDecoder.DecodePayload(ref m_eventData[eventID], payload);
+            WriteToAllListeners(
+                eventId: (int)eventID,
+                osThreadId: &osThreadID,
+                timeStamp: &timeStamp,
+                activityID: &activityId,
+                childActivityID: &childActivityId,
+                args: decodedPayloadFields);
+        }
+    }
+}

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/RuntimeEventSource.cs

@@ -0,0 +1,85 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Threading;
+
+namespace System.Diagnostics.Tracing
+{
+    /// <summary>
+    /// RuntimeEventSource is an EventSource that represents events emitted by the managed runtime.
+    /// </summary>
+    [EventSource(Guid = "49592C0F-5A05-516D-AA4B-A64E02026C89", Name = "System.Runtime")]
+    internal sealed class RuntimeEventSource : EventSource
+    {
+        internal const string EventSourceName = "System.Runtime";
+
+        private static RuntimeEventSource? s_RuntimeEventSource;
+        private PollingCounter? _gcHeapSizeCounter;
+        private IncrementingPollingCounter? _gen0GCCounter;
+        private IncrementingPollingCounter? _gen1GCCounter;
+        private IncrementingPollingCounter? _gen2GCCounter;
+        private PollingCounter? _cpuTimeCounter;
+        private PollingCounter? _workingSetCounter;
+        private PollingCounter? _threadPoolThreadCounter;
+        private IncrementingPollingCounter? _monitorContentionCounter;
+        private PollingCounter? _threadPoolQueueCounter;
+        private IncrementingPollingCounter? _completedItemsCounter;
+        private IncrementingPollingCounter? _allocRateCounter;
+        private PollingCounter? _timerCounter;
+
+#if !MONO
+        private IncrementingPollingCounter? _exceptionCounter;
+        private PollingCounter? _gcTimeCounter;
+        private PollingCounter? _gen0SizeCounter;
+        private PollingCounter? _gen1SizeCounter;
+        private PollingCounter? _gen2SizeCounter;
+        private PollingCounter? _lohSizeCounter;
+        private PollingCounter? _assemblyCounter;
+#endif
+
+        public static void Initialize()
+        {
+            s_RuntimeEventSource = new RuntimeEventSource();
+        }
+
+        private RuntimeEventSource() : base(new Guid(0x49592C0F, 0x5A05, 0x516D, 0xAA, 0x4B, 0xA6, 0x4E, 0x02, 0x02, 0x6C, 0x89), EventSourceName, EventSourceSettings.EtwSelfDescribingEventFormat)
+        {
+        }
+
+        protected override void OnEventCommand(EventCommandEventArgs command)
+        {
+            if (command.Command == EventCommand.Enable)
+            {
+                // NOTE: These counters will NOT be disposed on disable command because we may be introducing
+                // a race condition by doing that. We still want to create these lazily so that we aren't adding
+                // overhead by at all times even when counters aren't enabled.
+
+                // On disable, PollingCounters will stop polling for values so it should be fine to leave them around.
+                _cpuTimeCounter ??= new PollingCounter("cpu-usage", this, () => RuntimeEventSourceHelper.GetCpuUsage()) { DisplayName = "CPU Usage", DisplayUnits = "%" };
+                _workingSetCounter ??= new PollingCounter("working-set", this, () => (double)(Environment.WorkingSet / 1000000)) { DisplayName = "Working Set", DisplayUnits = "MB" };
+                _gcHeapSizeCounter ??= new PollingCounter("gc-heap-size", this, () => (double)(GC.GetTotalMemory(false) / 1000000)) { DisplayName = "GC Heap Size", DisplayUnits = "MB" };
+                _gen0GCCounter ??= new IncrementingPollingCounter("gen-0-gc-count", this, () => GC.CollectionCount(0)) { DisplayName = "Gen 0 GC Count", DisplayRateTimeScale = new TimeSpan(0, 1, 0) };
+                _gen1GCCounter ??= new IncrementingPollingCounter("gen-1-gc-count", this, () => GC.CollectionCount(1)) { DisplayName = "Gen 1 GC Count", DisplayRateTimeScale = new TimeSpan(0, 1, 0) };
+                _gen2GCCounter ??= new IncrementingPollingCounter("gen-2-gc-count", this, () => GC.CollectionCount(2)) { DisplayName = "Gen 2 GC Count", DisplayRateTimeScale = new TimeSpan(0, 1, 0) };
+                _threadPoolThreadCounter ??= new PollingCounter("threadpool-thread-count", this, () => ThreadPool.ThreadCount) { DisplayName = "ThreadPool Thread Count" };
+                _monitorContentionCounter ??= new IncrementingPollingCounter("monitor-lock-contention-count", this, () => Monitor.LockContentionCount) { DisplayName = "Monitor Lock Contention Count", DisplayRateTimeScale = new TimeSpan(0, 0, 1) };
+                _threadPoolQueueCounter ??= new PollingCounter("threadpool-queue-length", this, () => ThreadPool.PendingWorkItemCount) { DisplayName = "ThreadPool Queue Length" };
+                _completedItemsCounter ??= new IncrementingPollingCounter("threadpool-completed-items-count", this, () => ThreadPool.CompletedWorkItemCount) { DisplayName = "ThreadPool Completed Work Item Count", DisplayRateTimeScale = new TimeSpan(0, 0, 1) };
+                _allocRateCounter ??= new IncrementingPollingCounter("alloc-rate", this, () => GC.GetTotalAllocatedBytes()) { DisplayName = "Allocation Rate", DisplayUnits = "B", DisplayRateTimeScale = new TimeSpan(0, 0, 1) };
+                _timerCounter ??= new PollingCounter("active-timer-count", this, () => Timer.ActiveCount) { DisplayName = "Number of Active Timers" };
+
+#if !MONO
+                _exceptionCounter ??= new IncrementingPollingCounter("exception-count", this, () => Exception.GetExceptionCount()) { DisplayName = "Exception Count", DisplayRateTimeScale = new TimeSpan(0, 0, 1) };
+                _gcTimeCounter ??= new PollingCounter("time-in-gc", this, () => GC.GetLastGCPercentTimeInGC()) { DisplayName = "% Time in GC since last GC", DisplayUnits = "%" };
+                _gen0SizeCounter ??= new PollingCounter("gen-0-size", this, () => GC.GetGenerationSize(0)) { DisplayName = "Gen 0 Size", DisplayUnits = "B" };
+                _gen1SizeCounter ??= new PollingCounter("gen-1-size", this, () => GC.GetGenerationSize(1)) { DisplayName = "Gen 1 Size", DisplayUnits = "B" };
+                _gen2SizeCounter ??= new PollingCounter("gen-2-size", this, () => GC.GetGenerationSize(2)) { DisplayName = "Gen 2 Size", DisplayUnits = "B" };
+                _lohSizeCounter ??= new PollingCounter("loh-size", this, () => GC.GetGenerationSize(3)) { DisplayName = "LOH Size", DisplayUnits = "B" };
+                _assemblyCounter ??= new PollingCounter("assembly-count", this, () => System.Reflection.Assembly.GetAssemblyCount()) { DisplayName = "Number of Assemblies Loaded" };
+#endif
+            }
+
+        }
+    }
+}

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/RuntimeEventSourceHelper.Unix.cs

@@ -0,0 +1,14 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Diagnostics.Tracing
+{
+    internal static class RuntimeEventSourceHelper
+    {
+        private static Interop.Sys.ProcessCpuInformation s_cpuInfo;
+
+        internal static int GetCpuUsage() =>
+            Interop.Sys.GetCpuUtilization(ref s_cpuInfo) / Environment.ProcessorCount;
+    }
+}

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/RuntimeEventSourceHelper.Windows.cs

@@ -0,0 +1,49 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Diagnostics.Tracing
+{
+    internal static class RuntimeEventSourceHelper
+    {
+        private static long s_prevProcUserTime = 0;
+        private static long s_prevProcKernelTime = 0;
+        private static long s_prevSystemUserTime = 0;
+        private static long s_prevSystemKernelTime = 0;
+
+        internal static int GetCpuUsage()
+        {
+            // Returns the current process' CPU usage as a percentage
+
+            int cpuUsage;
+
+            if (!Interop.Kernel32.GetProcessTimes(Interop.Kernel32.GetCurrentProcess(), out _, out _, out long procKernelTime, out long procUserTime))
+            {
+                return 0;
+            }
+
+            if (!Interop.Kernel32.GetSystemTimes(out _, out long systemUserTime, out long systemKernelTime))
+            {
+                return 0;
+            }
+
+            if (s_prevSystemUserTime == 0 && s_prevSystemKernelTime == 0) // These may be 0 when we report CPU usage for the first time, in which case we should just return 0.
+            {
+                cpuUsage = 0;
+            }
+            else
+            {
+                long totalProcTime = (procUserTime - s_prevProcUserTime) + (procKernelTime - s_prevProcKernelTime);
+                long totalSystemTime = (systemUserTime - s_prevSystemUserTime) + (systemKernelTime - s_prevSystemKernelTime);
+                cpuUsage = (int)(totalProcTime * 100 / totalSystemTime);
+            }
+
+            s_prevProcUserTime = procUserTime;
+            s_prevProcKernelTime = procKernelTime;
+            s_prevSystemUserTime = systemUserTime;
+            s_prevSystemKernelTime = systemKernelTime;
+
+            return cpuUsage;
+        }
+    }
+}

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/TraceLogging/TraceLoggingEventHandleTable.cs

@@ -0,0 +1,61 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Threading;
+
+namespace System.Diagnostics.Tracing
+{
+#if FEATURE_PERFTRACING
+    /// <summary>
+    /// Per-EventSource data structure for caching EventPipe EventHandles associated with TraceLogging events.
+    /// </summary>
+    internal sealed class TraceLoggingEventHandleTable
+    {
+        private const int DefaultLength = 10;
+        private IntPtr[] m_innerTable;
+
+        internal TraceLoggingEventHandleTable()
+        {
+            m_innerTable = new IntPtr[DefaultLength];
+        }
+
+        internal IntPtr this[int eventID]
+        {
+            get
+            {
+                IntPtr ret = IntPtr.Zero;
+                IntPtr[] innerTable = Volatile.Read(ref m_innerTable);
+
+                if (eventID >= 0 && eventID < innerTable.Length)
+                {
+                    ret = innerTable[eventID];
+                }
+
+                return ret;
+            }
+        }
+
+        internal void SetEventHandle(int eventID, IntPtr eventHandle)
+        {
+            // Set operations must be serialized to ensure that re-size operations don't lose concurrent writes.
+            Debug.Assert(Monitor.IsEntered(this));
+
+            if (eventID >= m_innerTable.Length)
+            {
+                int newSize = m_innerTable.Length * 2;
+                if (newSize <= eventID)
+                {
+                    newSize = eventID + 1;
+                }
+
+                IntPtr[] newTable = new IntPtr[newSize];
+                Array.Copy(m_innerTable, newTable, m_innerTable.Length);
+                Volatile.Write(ref m_innerTable, newTable);
+            }
+
+            m_innerTable[eventID] = eventHandle;
+        }
+    }
+#endif
+}

src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/TraceLogging/TraceLoggingEventSource.cs

@@ -523,8 +523,7 @@ namespace System.Diagnostics.Tracing
 
             fixed (EventSourceOptions* pOptions = &options)
             {
-                EventDescriptor descriptor;
-                NameInfo? nameInfo = this.UpdateDescriptor(eventName, eventTypes, ref options, out descriptor);
+                NameInfo? nameInfo = this.UpdateDescriptor(eventName, eventTypes, ref options, out EventDescriptor descriptor);
                 if (nameInfo == null)
                 {
                     return;
@@ -591,9 +590,8 @@ namespace System.Diagnostics.Tracing
             {
                 fixed (EventSourceOptions* pOptions = &options)
                 {
-                    EventDescriptor descriptor;
                     options.Opcode = options.IsOpcodeSet ? options.Opcode : GetOpcodeWithDefault(options.Opcode, eventName);
-                    NameInfo? nameInfo = this.UpdateDescriptor(eventName, eventTypes, ref options, out descriptor);
+                    NameInfo? nameInfo = this.UpdateDescriptor(eventName, eventTypes, ref options, out EventDescriptor descriptor);
                     if (nameInfo == null)
                     {
                         return;
@@ -764,8 +762,7 @@ namespace System.Diagnostics.Tracing
                     if (m_traits[i].StartsWith("ETW_", StringComparison.Ordinal))
                     {
                         string etwTrait = m_traits[i].Substring(4);
-                        byte traitNum;
-                        if (!byte.TryParse(etwTrait, out traitNum))
+                        if (!byte.TryParse(etwTrait, out byte traitNum))
                         {
                             if (etwTrait == "GROUP")
                             {