Wasm: enable stack trace exceptions, simple exceptions test, upgrade emscripten (#8319)

eng/install-emscripten.cmd

@@ -5,14 +5,14 @@ git clone https://github.com/emscripten-core/emsdk.git
 
 cd emsdk
 rem checkout a known good version to avoid a random break when emscripten changes the top of tree.
-git checkout c1f0ad9
+git checkout def6e49
 
 powershell -NoProfile -NoLogo -ExecutionPolicy ByPass -command "& """%~dp0update-machine-certs.ps1""" %*"
 
 rem Use the python that is downloaded to native-tools explicitly as its not on the path
-call "%1"\..\native-tools\bin\python3 emsdk.py install 2.0.0
+call "%1"\..\native-tools\bin\python3 emsdk.py install 2.0.3
 if %errorlevel% NEQ 0 goto fail
-call emsdk activate 2.0.0
+call emsdk activate 2.0.3
 if %errorlevel% NEQ 0 goto fail
 
 exit /b 0

src/ILCompiler.WebAssembly/src/CodeGen/ILToWebAssemblyImporter.cs

@@ -4539,13 +4539,25 @@ namespace Internal.IL
 
         void ThrowOrRethrow(StackEntry exceptionObject)
         {
+            int offset = GetTotalParameterOffset() + GetTotalLocalOffset();
+            LLVMValueRef shadowStack = _builder.BuildGEP(_currentFunclet.GetParam(0),
+                new LLVMValueRef[] { LLVMValueRef.CreateConstInt(LLVMTypeRef.Int32, (uint)offset, false) },
+                String.Empty);
+            LLVMValueRef exSlot = _builder.BuildBitCast(shadowStack, LLVMTypeRef.CreatePointer(LLVMTypeRef.CreatePointer(LLVMTypeRef.Int8, 0), 0));
+            _builder.BuildStore(exceptionObject.ValueAsType(LLVMTypeRef.CreatePointer(LLVMTypeRef.Int8, 0), _builder), exSlot);
+            LLVMValueRef[] llvmArgs = new LLVMValueRef[] { shadowStack };
+            MetadataType helperType = _compilation.TypeSystemContext.SystemModule.GetKnownType("System", "Exception");
+            MethodDesc helperMethod = helperType.GetKnownMethod("DispatchExWasm", null);
+            LLVMValueRef fn = LLVMFunctionForMethod(helperMethod, helperMethod, null, false, null, null, out bool hasHiddenParam, out LLVMValueRef dictPtrPtrStore, out LLVMValueRef fatFunctionPtr);
+            ExceptionRegion currentExceptionRegion = GetCurrentTryRegion();
+            _builder.BuildCall(fn, llvmArgs, string.Empty);
+
             if (RhpThrowEx.Handle.Equals(IntPtr.Zero))
             {
                 RhpThrowEx = Module.AddFunction("RhpThrowEx", LLVMTypeRef.CreateFunction(LLVMTypeRef.Void, new LLVMTypeRef[] { LLVMTypeRef.CreatePointer(LLVMTypeRef.Int8, 0) }, false));
             }
 
             LLVMValueRef[] args = new LLVMValueRef[] { exceptionObject.ValueAsType(LLVMTypeRef.CreatePointer(LLVMTypeRef.Int8, 0), _builder) };
-            ExceptionRegion currentExceptionRegion = GetCurrentTryRegion();
             if (currentExceptionRegion == null)
             {
                 _builder.BuildCall(RhpThrowEx, args, "");

src/System.Private.CoreLib/src/System.Private.CoreLib.csproj

@@ -239,6 +239,7 @@
     <Compile Include="System\Delegate.DefaultParameters.cs" />
     <Compile Include="System\RuntimeTypeHandle.cs" />
     <Compile Include="System\Exception.CoreRT.cs" />
+    <Compile Include="System\Exception.CoreRT.Wasm.cs" Condition="'$(Platform)'=='wasm'"/>
     <Compile Include="System\RuntimeExceptionHelpers.cs" />
     <Compile Include="System\EETypePtr.cs" />
     <Compile Include="System\Runtime\RuntimeImports.cs" />

src/System.Private.CoreLib/src/System/Diagnostics/StackTrace.CoreRT.Wasm.cs

@@ -22,10 +22,11 @@ namespace System.Diagnostics
             // at S_P_CoreLib_System_Diagnostics_StackTrace__InitializeForCurrentThread (wasm-function[12314]:275)
             // at S_P_CoreLib_System_Diagnostics_StackTrace___ctor_0(wasm-function[12724]:118)
             skipFrames += 2; // METHODS_TO_SKIP is a constant so just change here
+            // at S_P_CoreLib_System_Exception__DispatchExWasm(wasm-function[2360]:39)
 
             fixed (byte* curChar = backtraceBuffer)
             {
-                callstackLen = emscripten_get_callstack(8 /* original source stack if source maps available, not tested */, curChar, backtraceBuffer.Length);
+                callstackLen = emscripten_get_callstack(0, curChar, backtraceBuffer.Length);
             }
             int _numOfFrames = 1;
             int lineStartIx = 0;

src/System.Private.CoreLib/src/System/Exception.CoreRT.Wasm.cs

@@ -0,0 +1,42 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+
+namespace System
+{
+    public partial class Exception
+    {
+        [DllImport("*")]
+        internal static extern void RhpThrowEx(object exception);
+
+        private static void DispatchExWasm(object exception)
+        {
+            AppendExceptionStackFrameWasm(exception, new StackTrace(1).ToString());
+            //RhpThrowEx(exception); can't as not handling the transition unmanaged->managed in the landing pads.
+        }
+
+        private static void AppendExceptionStackFrameWasm(object exceptionObj, string stackTraceString)
+        {
+            // This method is called by the runtime's EH dispatch code and is not allowed to leak exceptions
+            // back into the dispatcher.
+            try
+            {
+                Exception ex = exceptionObj as Exception;
+                if (ex == null)
+                    Environment.FailFast("Exceptions must derive from the System.Exception class");
+
+                if (!RuntimeExceptionHelpers.SafeToPerformRichExceptionSupport)
+                    return;
+
+                ex._stackTraceString = stackTraceString.Replace("__", ".").Replace("_", ".");
+            }
+            catch
+            {
+                // We may end up with a confusing stack trace or a confusing ETW trace log, but at least we
+                // can continue to dispatch this exception.
+            }
+        }
+    }
+}

tests/src/Simple/Exceptions/Exceptions.cmd

@@ -1,6 +1,12 @@
 @echo off
 setlocal
-"%1\%2"
+
+IF /i "%__Mode%"=="wasm" (
+    call %EMSDK_NODE% "%1\%2"
+) ELSE (
+    "%1\%2"
+)
+
 set ErrorCode=%ERRORLEVEL%
 IF "%ErrorCode%"=="100" (
     echo %~n0: pass

tests/src/Simple/Exceptions/Exceptions.cs

@@ -3,6 +3,10 @@
 
 using System;
 using System.Text;
+#if CODEGEN_WASM
+using System.Runtime.InteropServices;
+using Console=BringUpTest.Console;
+#endif
 
 public class BringUpTest
 {
@@ -53,7 +57,11 @@ public class BringUpTest
             }
 
             string stackTrace = e.StackTrace;
+#if CODEGEN_WASM && !DEBUG  //Wasm doesn't get useful names in release mode, e.g. it gets at wasm-function[10259]:0x4b5182
+            if (!stackTrace.Contains("wasm-function"))
+#else
             if (!stackTrace.Contains("BringUpTest.Main"))
+#endif
             {
                 Console.WriteLine("Unexpected stack trace: " + stackTrace);
                 return Fail;
@@ -198,5 +206,45 @@ public class BringUpTest
         CreateSomeGarbage();
         return true;
     }
+
+#if CODEGEN_WASM
+    internal class Console
+    {
+        private static unsafe void PrintString(string s)
+        {
+            int length = s.Length;
+            fixed (char* curChar = s)
+            {
+                for (int i = 0; i < length; i++)
+                {
+                    TwoByteStr curCharStr = new TwoByteStr();
+                    curCharStr.first = (byte)(*(curChar + i));
+                    printf((byte*)&curCharStr, null);
+                }
+            }
+        }
+
+        internal static void WriteLine(string s)
+        {
+            PrintString(s);
+            PrintString("\n");
+        }
+
+        internal static void WriteLine(string format, string p)
+        {
+            PrintString(string.Format(format, p));
+            PrintString("\n");
+        }
+    }
+
+    struct TwoByteStr
+    {
+        public byte first;
+        public byte second;
+    }
+
+    [DllImport("*")]
+    private static unsafe extern int printf(byte* str, byte* unused);
+#endif
 }