Merge pull request #805 from Sergio0694/dev/workaround-fxc-float-bug

Always emit 'asfloat' for float literals in D2D shaders
Sergio0694 · Jun 5, 2024 · 908d691 · 908d691
2 parents deab9f5 + b4c5b4d
commit 908d691
Show file tree

Hide file tree

Showing 10 changed files with 68 additions and 16 deletions.
diff --git a/src/ComputeSharp.SourceGeneration.Hlsl/SyntaxRewriters/HlslSourceRewriter.cs b/src/ComputeSharp.SourceGeneration.Hlsl/SyntaxRewriters/HlslSourceRewriter.cs
@@ -196,7 +196,7 @@ public sealed override SyntaxNode VisitDefaultExpression(DefaultExpressionSyntax
     }
 
     /// <inheritdoc/>
-    public sealed override SyntaxNode? VisitLiteralExpression(LiteralExpressionSyntax node)
+    public sealed unsafe override SyntaxNode? VisitLiteralExpression(LiteralExpressionSyntax node)
     {
         CancellationToken.ThrowIfCancellationRequested();
 
@@ -219,6 +219,7 @@ public sealed override SyntaxNode VisitDefaultExpression(DefaultExpressionSyntax
             // in HLSL, we can remove the suffix entirely. As for 64 bit values, we simply use the 'L' suffix.
             if (type.SpecialType == SpecialType.System_Single)
             {
+#if D3D12_SOURCE_GENERATOR
                 string literal = updatedNode.Token.ValueText;
 
                 // If the numeric literal is neither a decimal nor an exponential, add the ".0" suffix
@@ -228,6 +229,25 @@ public sealed override SyntaxNode VisitDefaultExpression(DefaultExpressionSyntax
                 }
 
                 return updatedNode.WithToken(Literal(literal, 0f));
+#else
+                // When compiling for D2D, we need to emit 'asfloat' expressions to work around an FXC
+                // bug that can cause it to sometimes emit incorrect values for float literals. For
+                // additional context, see: https://github.com/Sergio0694/ComputeSharp/issues/780.
+                //
+                // This code rewrites expressions as follows:
+                // C#:   3.14f
+                // HLSL: asfloat(1078523331)
+                float literalValue = (float)operation.ConstantValue.Value!;
+                uint literalValueAsUInt = *(uint*)&literalValue;
+
+                return
+                    InvocationExpression(IdentifierName("asfloat"))
+                    .AddArgumentListArguments(
+                        Argument(
+                            LiteralExpression(
+                                SyntaxKind.NumericLiteralExpression,
+                                Literal(literalValueAsUInt))));
+#endif
             }
             else if (type.SpecialType == SpecialType.System_Double)
             {

diff --git a/tests/ComputeSharp.D2D1.Tests.SourceGenerators/Test_D2DPixelShaderDescriptorGenerator.cs b/tests/ComputeSharp.D2D1.Tests.SourceGenerators/Test_D2DPixelShaderDescriptorGenerator.cs
@@ -186,8 +186,8 @@ partial struct MyShader : global::ComputeSharp.D2D1.Descriptors.ID2D1PixelShader
                         {
                             int2 xy = (int2)D2DGetScenePosition().xy;
                             float2 uv = xy / (float2)dispatchSize;
-                            float3 col = 0.5 + (0.5 * cos(time + float3(uv, uv.x) + float3(0, 2, 4)));
-                            return float4(col, 1.0);
+                            float3 col = asfloat(1056964608U) + (asfloat(1056964608U) * cos(time + float3(uv, uv.x) + float3(0, 2, 4)));
+                            return float4(col, asfloat(1065353216U));
                         }
                         """;
 
@@ -482,8 +482,8 @@ partial struct MyShader : global::ComputeSharp.D2D1.Descriptors.ID2D1PixelShader
                         {
                             int2 xy = (int2)D2DGetScenePosition().xy;
                             float2 uv = xy / (float2)dispatchSize;
-                            float3 col = 0.5 + (0.5 * cos(time + float3(uv, uv.x) + float3(0, 2, 4)));
-                            return float4(col, 1.0);
+                            float3 col = asfloat(1056964608U) + (asfloat(1056964608U) * cos(time + float3(uv, uv.x) + float3(0, 2, 4)));
+                            return float4(col, asfloat(1065353216U));
                         }
                         """;
 
@@ -830,8 +830,8 @@ partial struct MyShader : global::ComputeSharp.D2D1.Descriptors.ID2D1PixelShader
                         {
                             int2 xy = (int2)D2DGetScenePosition().xy;
                             float2 uv = xy / (float2)dispatchSize;
-                            float3 col = 0.5 + (0.5 * cos(time + float3(uv, uv.x) + float3(0, 2, 4)));
-                            return float4(col, 1.0);
+                            float3 col = asfloat(1056964608U) + (asfloat(1056964608U) * cos(time + float3(uv, uv.x) + float3(0, 2, 4)));
+                            return float4(col, asfloat(1065353216U));
                         }
                         """;
 
@@ -1124,8 +1124,8 @@ partial struct MyShader : global::ComputeSharp.D2D1.Descriptors.ID2D1PixelShader
                         {
                             int2 xy = (int2)D2DGetScenePosition().xy;
                             float2 uv = xy / (float2)dispatchSize;
-                            float3 col = 0.5 + (0.5 * cos(time + float3(uv, uv.x) + float3(0, 2, 4)));
-                            return float4(col, 1.0);
+                            float3 col = asfloat(1056964608U) + (asfloat(1056964608U) * cos(time + float3(uv, uv.x) + float3(0, 2, 4)));
+                            return float4(col, asfloat(1065353216U));
                         }
                         """;
 

diff --git a/tests/ComputeSharp.D2D1.Tests/Assets/Green32x32.png b/tests/ComputeSharp.D2D1.Tests/Assets/Green32x32.png
diff --git a/tests/ComputeSharp.D2D1.Tests/Assets/TerracedHills.png b/tests/ComputeSharp.D2D1.Tests/Assets/TerracedHills.png
diff --git a/tests/ComputeSharp.D2D1.Tests/ComputeSharp.D2D1.Tests.csproj b/tests/ComputeSharp.D2D1.Tests/ComputeSharp.D2D1.Tests.csproj
@@ -90,12 +90,15 @@
     <None Update="Assets\ContouredLayers.png">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
-    <None Include="..\ComputeSharp.Tests\Assets\TerracedHills.png" Link="Assets\TerracedHills.png">
+    <None Include="Assets\TerracedHills.png">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
     <None Update="Assets\RadialFadeOut.png">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
+    <None Update="Assets\Green32x32.png">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
     <None Include="..\..\samples\ComputeSharp.SwapChain\Textures\RustyMetal.png" Link="Assets\Textures\RustyMetal.png" CopyToOutputDirectory="PreserveNewest" />
   </ItemGroup>
 

diff --git a/tests/ComputeSharp.D2D1.Tests/D2D1ReflectionServicesTests.cs b/tests/ComputeSharp.D2D1.Tests/D2D1ReflectionServicesTests.cs
@@ -42,7 +42,7 @@ public void GetShaderInfo()
                 float4 input1 = D2DGetInput(1);
                 float4 input2 = D2DSampleInputAtPosition(2, xy + offset);
                 float value3 = __reserved__buffer[0];
-                float4 value4 = __reserved__texture.Sample(__sampler____reserved__texture, float2(0, 0.5));
+                float4 value4 = __reserved__texture.Sample(__sampler____reserved__texture, float2(0, asfloat(1056964608U)));
                 return input0 + input1 + input2 + value3 + value4;
             }
             """, shaderInfo.HlslSource);

diff --git a/tests/ComputeSharp.D2D1.Tests/ShaderRewriterTests.cs b/tests/ComputeSharp.D2D1.Tests/ShaderRewriterTests.cs
@@ -1,4 +1,5 @@
 using ComputeSharp.D2D1.Interop;
+using ComputeSharp.D2D1.Tests.Helpers;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
 #pragma warning disable CA1822
@@ -82,7 +83,7 @@ public void KnownNamedIntrinsic_ConditionalSelect()
             D2D_PS_ENTRY(Execute)
             {
                 bool4 mask4 = bool4(true, false, true, true);
-                float4 float4_1 = float4(1, 2, 3.14, 4);
+                float4 float4_1 = float4(1, 2, asfloat(1078523331U), 4);
                 float4 float4_2 = float4(5, 6, 7, 8);
                 float4 float4_r = (mask4 ? float4_1 : float4_2);
                 bool1x3 mask1x3 = bool1x3((bool)true, (bool)true, (bool)false);
@@ -93,7 +94,7 @@ public void KnownNamedIntrinsic_ConditionalSelect()
                 uint2x4 uint2x4_1 = uint2x4((uint)1, (uint)2, (uint)3, (uint)4, (uint)5, (uint)6, (uint)7, (uint)8);
                 uint2x4 uint2x4_2 = uint2x4((uint)111, (uint)222, (uint)333, (uint)444, (uint)555, (uint)666, (uint)777, (uint)888);
                 uint2x4 uint2x4_r = (mask2x4 ? uint2x4_1 : uint2x4_2);
-                float2x2 f2x2_r = mul((float2x4)uint2x4_r, float4x2((float2)float4_r.xy, (float2)float4_r.zw, (float2)float2(int1x3_r._m00, int1x3_r._m01), (float2)float2(int1x3_r._m02, 1.0)));
+                float2x2 f2x2_r = mul((float2x4)uint2x4_r, float4x2((float2)float4_r.xy, (float2)float4_r.zw, (float2)float2(int1x3_r._m00, int1x3_r._m01), (float2)float2(int1x3_r._m02, asfloat(1065353216U))));
                 return float4(f2x2_r._m00, f2x2_r._m01, f2x2_r._m10, f2x2_r._m11);
             }
             """, shaderInfo.HlslSource);
@@ -179,4 +180,32 @@ public float4 Execute()
                 mask2x3_r_or.M11 ? 1 : 0);
         }
     }
+
+    // See https://github.com/Sergio0694/ComputeSharp/issues/780
+    [TestMethod]
+    public void ProblematicFloatLiteralValue_IsRewrittenCorrectly()
+    {
+        D2D1TestRunner.RunAndCompareShader(
+            new ProblematicFloatLiteralValueShader(131072.65f),
+            32,
+            32,
+            "Green32x32.png");
+    }
+
+    [D2DInputCount(0)]
+    [D2DShaderProfile(D2D1ShaderProfile.PixelShader50)]
+    [D2DOutputBuffer(D2D1BufferPrecision.Float32)]
+    [D2DGeneratedPixelShaderDescriptor]
+    internal readonly partial struct ProblematicFloatLiteralValueShader(float x) : ID2D1PixelShader
+    {
+        public float4 Execute()
+        {
+            if (x != 131072.65f)
+            {
+                return 0;
+            }
+
+            return new float4(0.0f, 1.0f, 0.0f, 1.0f);
+        }
+    }
 }
diff --git a/tests/ComputeSharp.D2D1.Tests/ShadersTests.cs b/tests/ComputeSharp.D2D1.Tests/ShadersTests.cs
@@ -110,7 +110,7 @@ public unsafe void ContouredLayers()
     [TestMethod]
     public void TerracedHills()
     {
-        RunTest<TerracedHills>(0.000026f);
+        RunTest<TerracedHills>(0.000027f);
     }
 
     private static void RunTest<T>(float threshold = 0.00001f)

diff --git a/tests/ComputeSharp.D2D1.WinUI.Tests/ComputeSharp.D2D1.WinUI.Tests.csproj b/tests/ComputeSharp.D2D1.WinUI.Tests/ComputeSharp.D2D1.WinUI.Tests.csproj
@@ -42,7 +42,7 @@
       <Link>Assets\Shaders\ProteanClouds.png</Link>
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
-    <Content Include="..\ComputeSharp.Tests\Assets\TerracedHills.png">
+    <Content Include="..\ComputeSharp.D2D1.Tests\Assets\TerracedHills.png">
       <Link>Assets\Shaders\TerracedHills.png</Link>
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>

diff --git a/tests/ComputeSharp.D2D1.WinUI.Tests/Tests/ShadersTests.cs b/tests/ComputeSharp.D2D1.WinUI.Tests/Tests/ShadersTests.cs
@@ -68,7 +68,7 @@ public async Task ProteanClouds(WrapperType wrapperType)
     [DataRow(WrapperType.CanvasEffect)]
     public async Task TerracedHills(WrapperType wrapperType)
     {
-        await RunTestAsync<TerracedHills>(wrapperType, 0.000026f);
+        await RunTestAsync<TerracedHills>(wrapperType, 0.000027f);
     }
 
     private static async Task RunTestAsync<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] T>(WrapperType wrapperType, float threshold = 0.00001f)