[Metal][Generator] Fix the SetBuffers methods in protocols. Fixes #9649 (#9651)

Add fixes for Metal for XAM_CORE_4. Fixing the methods takes us to a dangerous path, so we do not do it unless we have issues about the methods.

Fixes https://github.com/xamarin/xamarin-macios/issues/9649

src/Metal/MTLArgumentEncoder.cs

@@ -1,11 +1,40 @@
 using System;
+using System.Runtime.InteropServices;
+using Foundation;
+using ObjCRuntime;
 
 namespace Metal {
+
+
 	public static partial class MTLArgumentEncoder_Extensions {
+#if XAMCORE_4_0
+		public static void SetBuffers (this IMTLArgumentEncoder encoder, IMTLBuffer[] buffers, nuint[] offsets, NSRange range)
+		{
+			if (buffers == null)
+				throw new ArgumentNullException (nameof (buffers));
+			if (offsets == null)
+				throw new ArgumentNullException (nameof (offsets));
+
+			var bufferPtrArray = buffers.Length <= 1024 ? stackalloc IntPtr[buffers.Length] : new IntPtr [buffers.Length];
+			// get all intptr from the array to pass to the lower level call
+			for (var i = 0; i < buffers.Length; i++) {
+				bufferPtrArray [i] = buffers [i].Handle;
+			}
+
+			unsafe {
+				fixed (void* buffersPtr = bufferPtrArray)
+				fixed (void* offsetsPtr = offsets) { // can use fixed
+					encoder.SetBuffers ((IntPtr) buffersPtr, (IntPtr) offsetsPtr, range);
+				}
+			}
+			GC.KeepAlive (buffers)
+		}
+#else 
 		public unsafe static void SetBuffers (this IMTLArgumentEncoder This, IMTLBuffer [] buffers, nint [] offsets, Foundation.NSRange range)
 		{
 			fixed (void* handle = offsets)
 				This.SetBuffers (buffers, (IntPtr)handle, range);
 		}
+#endif
 	}
 }

src/Metal/MTLComputeCommandEncoder.cs

@@ -0,0 +1,36 @@
+using System;
+using System.Runtime.InteropServices;
+using Foundation;
+using ObjCRuntime;
+
+namespace Metal {
+
+#if XAMCORE_4_0
+
+	// add some extension methods to make the API of the protocol nicer
+	public static class IMTLComputeCommandEncoderExtensions {
+
+		public static void SetBuffers (this IMTLComputeCommandEncoder table, IMTLBuffer[] buffers, nuint[] offsets, NSRange range)
+		{
+			if (buffers == null)
+				throw new ArgumentNullException (nameof (buffers));
+			if (offsets == null)
+				throw new ArgumentNullException (nameof (offsets));
+
+			var bufferPtrArray = buffers.Length <= 1024 ? stackalloc IntPtr[buffers.Length] : new IntPtr [buffers.Length];
+			// get all intptr from the array to pass to the lower level call
+			for (var i = 0; i < buffers.Length; i++) {
+				bufferPtrArray [i] = buffers [i].Handle;
+			}
+
+			unsafe {
+				fixed (void* buffersPtr = bufferPtrArray)
+				fixed (void* offsetsPtr = offsets) { // can use fixed
+					table.SetBuffers ((IntPtr) buffersPtr, (IntPtr) offsetsPtr, range);
+				}
+			}
+			GC.KeepAlive (buffers)
+		}
+	}
+#endif
+}

src/frameworks.sources

@@ -1078,6 +1078,7 @@ METAL_SOURCES = \
 	Metal/MTLArgumentEncoder.cs \
 	Metal/MTLBlitPassSampleBufferAttachmentDescriptorArray.cs \
 	Metal/MTLCompat.cs \
+	Metal/MTLComputeCommandEncoder.cs \
 	Metal/MTLComputePassSampleBufferAttachmentDescriptorArray.cs \
 	Metal/MTLDevice.cs \
 	Metal/MTLIntersectionFunctionTable.cs \

src/metal.cs

@@ -495,9 +495,16 @@ namespace Metal {
 		[Export ("dispatchThreadgroupsWithIndirectBuffer:indirectBufferOffset:threadsPerThreadgroup:")]
 		void DispatchThreadgroups (IMTLBuffer indirectBuffer, nuint indirectBufferOffset, MTLSize threadsPerThreadgroup);
 
+#if XAMCORE_4_0
+		[Abstract]
+		[Export ("setBuffers:offsets:withRange:")]
+		void SetBuffers (IntPtr buffers, IntPtr offsets, NSRange range);
+#else
 		[Abstract]
 		[Export ("setBuffers:offsets:withRange:")]
 		void SetBuffers (IMTLBuffer [] buffers, IntPtr offsets, NSRange range);
+#endif
+
 
 		[Abstract]
 		[Export ("setSamplerStates:lodMinClamps:lodMaxClamps:withRange:")]
@@ -3911,9 +3918,15 @@ namespace Metal {
 		[Export ("setBuffer:offset:atIndex:")]
 		void SetBuffer ([NullAllowed] IMTLBuffer buffer, nuint offset, nuint index);
 
+#if XAMCORE_4_0
+		[Abstract]
+		[Export ("setBuffers:offsets:withRange:")]
+		void SetBuffers (IntPtr buffers, IntPtr offsets, NSRange range);
+#else
 		[Abstract]
 		[Export ("setBuffers:offsets:withRange:")]
 		void SetBuffers (IMTLBuffer[] buffers, IntPtr offsets, NSRange range);
+#endif
 
 		[Abstract]
 		[Export ("setTexture:atIndex:")]

tests/generator/BGenTests.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;

tests/monotouch-test/Metal/MTLArgumentEncoderTest.cs

@@ -0,0 +1,69 @@
+#if !__WATCHOS__
+
+using System;
+using Foundation;
+using Metal;
+
+using NUnit.Framework;
+
+namespace MonoTouchFixtures.Metal {
+
+	[TestFixture]
+	public class MTLArgumentEncoderTest {
+		IMTLDevice device;
+		IMTLLibrary library;
+		IMTLFunction function;
+		IMTLArgumentEncoder encoder;
+
+		[SetUp]
+		public void SetUp ()
+		{
+			device = MTLDevice.SystemDefault;
+			// some older hardware won't have a default
+			if (device == null)
+				Assert.Inconclusive ("Metal is not supported");
+
+			library = device.CreateDefaultLibrary ();
+			if (library == null)  // this happens on a simulator
+				Assert.Inconclusive ("Could not get the functions library for the device.");
+
+			if (library.FunctionNames.Length == 0)
+				Assert.Inconclusive ("Could not get functions for the pipeline.");
+
+			function = library.CreateFunction (library.FunctionNames [0]);
+			encoder = function.CreateArgumentEncoder (0);
+		}
+
+		[TearDown]
+		public void TearDown ()
+		{
+			library?.Dispose ();
+			library = null;
+			function?.Dispose ();
+			function = null;
+			encoder?.Dispose ();
+			encoder = null;
+		}
+
+#if XAMCORE_4_0
+		[Test]
+		public void SetBuffers ()
+		{
+			Assert.Throws<ArgumentNullException> (() => {
+				encoder.SetBuffers (null, new nuint [0], new NSRange ());
+			}, "Null buffers should throw.");
+
+			Assert.Throws<ArgumentNullException> (() => {
+				encoder.SetBuffers (new IMTLBuffer [0], null, new NSRange ());
+			}, "Null offsets should throw.");
+
+			// assert we do not crash or throw, we are testing the extension method
+			Assert.DoesNotThrow (() => {
+				encoder.SetBuffers (new IMTLBuffer [0], new nuint [0], new NSRange ());
+
+			}, "Should not throw");
+		}
+#endif
+	}
+}
+#endif

tests/monotouch-test/Metal/MTLComputeCommandEncoderTest.cs

@@ -0,0 +1,69 @@
+#if !__WATCHOS__
+
+using System;
+using Foundation;
+using Metal;
+
+using NUnit.Framework;
+
+namespace MonoTouchFixtures.Metal {
+
+	[TestFixture]
+	public class MTLComputeCommandEncoderTest {
+		IMTLDevice device;
+		IMTLCommandQueue commandQ;
+		IMTLCommandBuffer commandBuffer;
+		IMTLComputeCommandEncoder encoder;
+
+		[SetUp]
+		public void SetUp ()
+		{
+			device = MTLDevice.SystemDefault;
+			// some older hardware won't have a default
+			if (device == null)
+				Assert.Inconclusive ("Metal is not supported");
+
+			commandQ = device.CreateCommandQueue ();
+			if (commandQ == null)  // this happens on a simulator
+				Assert.Inconclusive ("Could not get the functions library for the device.");
+
+			commandBuffer = commandQ.CommandBuffer ();
+			if (commandBuffer == null) // happens on sim
+				Assert.Inconclusive ("Could not get the command buffer for the device.");
+
+			encoder = commandBuffer.ComputeCommandEncoder;
+		}
+
+		[TearDown]
+		public void TearDown ()
+		{
+			commandQ?.Dispose ();
+			commandQ = null;
+			commandBuffer?.Dispose ();
+			commandBuffer = null;
+			encoder?.Dispose ();
+			encoder = null;
+		}
+
+#if XAMCORE_4_0
+		[Test]
+		public void SetBuffers ()
+		{
+			Assert.Throws<ArgumentNullException> (() => {
+				encoder.SetBuffers (null, new nuint [0], new NSRange ());
+			}, "Null buffers should throw.");
+
+			Assert.Throws<ArgumentNullException> (() => {
+				encoder.SetBuffers (new IMTLBuffer [0], null, new NSRange ());
+			}, "Null offsets should throw.");
+
+			// assert we do not crash or throw, we are testing the extension method
+			Assert.DoesNotThrow (() => {
+				encoder.SetBuffers (new IMTLBuffer [0], new nuint [0], new NSRange ());
+
+			}, "Should not throw");
+		}
+#endif
+	}
+}
+#endif