[llvm] [DirectX] Add DXIL_MODULE_FLAG for ShaderFlags. (PR #83217)

[Tex Riddell via llvm-commits]

================
@@ -13,43 +13,58 @@ CONTAINER_PART(PSG1)
 
 #ifdef SHADER_FEATURE_FLAG
 
-SHADER_FEATURE_FLAG(0, Doubles, "Double-precision floating point")
-SHADER_FEATURE_FLAG(1, ComputeShadersPlusRawAndStructuredBuffers, "Raw and Structured buffers")
-SHADER_FEATURE_FLAG(2, UAVsAtEveryStage, "UAVs at every shader stage")
-SHADER_FEATURE_FLAG(3, Max64UAVs, "64 UAV slots")
-SHADER_FEATURE_FLAG(4, MinimumPrecision, "Minimum-precision data types")
-SHADER_FEATURE_FLAG(5, DX11_1_DoubleExtensions, "Double-precision extensions for 11.1")
-SHADER_FEATURE_FLAG(6, DX11_1_ShaderExtensions, "Shader extensions for 11.1")
-SHADER_FEATURE_FLAG(7, LEVEL9ComparisonFiltering, "Comparison filtering for feature level 9")
-SHADER_FEATURE_FLAG(8, TiledResources, "Tiled resources")
-SHADER_FEATURE_FLAG(9, StencilRef, "PS Output Stencil Ref")
-SHADER_FEATURE_FLAG(10, InnerCoverage, "PS Inner Coverage")
-SHADER_FEATURE_FLAG(11, TypedUAVLoadAdditionalFormats, "Typed UAV Load Additional Formats")
-SHADER_FEATURE_FLAG(12, ROVs, "Raster Ordered UAVs")
-SHADER_FEATURE_FLAG(13, ViewportAndRTArrayIndexFromAnyShaderFeedingRasterizer, "SV_RenderTargetArrayIndex or SV_ViewportArrayIndex from any shader feeding rasterizer")
-SHADER_FEATURE_FLAG(14, WaveOps, "Wave level operations")
-SHADER_FEATURE_FLAG(15, Int64Ops, "64-Bit integer")
-SHADER_FEATURE_FLAG(16, ViewID, "View Instancing")
-SHADER_FEATURE_FLAG(17, Barycentrics, "Barycentrics")
-SHADER_FEATURE_FLAG(18, NativeLowPrecision, "Use native low precision")
-SHADER_FEATURE_FLAG(19, ShadingRate, "Shading Rate")
-SHADER_FEATURE_FLAG(20, Raytracing_Tier_1_1, "Raytracing tier 1.1 features")
-SHADER_FEATURE_FLAG(21, SamplerFeedback, "Sampler feedback")
-SHADER_FEATURE_FLAG(22, AtomicInt64OnTypedResource, "64-bit Atomics on Typed Resources")
-SHADER_FEATURE_FLAG(23, AtomicInt64OnGroupShared, "64-bit Atomics on Group Shared")
-SHADER_FEATURE_FLAG(24, DerivativesInMeshAndAmpShaders, "Derivatives in mesh and amplification shaders")
-SHADER_FEATURE_FLAG(25, ResourceDescriptorHeapIndexing, "Resource descriptor heap indexing")
-SHADER_FEATURE_FLAG(26, SamplerDescriptorHeapIndexing, "Sampler descriptor heap indexing")
-SHADER_FEATURE_FLAG(27, RESERVED, "<RESERVED>")
-SHADER_FEATURE_FLAG(28, AtomicInt64OnHeapResource, "64-bit Atomics on Heap Resources")
-SHADER_FEATURE_FLAG(29, AdvancedTextureOps, "Advanced Texture Ops")
-SHADER_FEATURE_FLAG(30, WriteableMSAATextures, "Writeable MSAA Textures")
-
-SHADER_FEATURE_FLAG(31, NextUnusedBit, "Next reserved shader flag bit (not a flag)")
+// SHADER_FEATURE_FLAG(bit offset for the flag, bit offset for DXIL module flag, name, description.
+
+SHADER_FEATURE_FLAG(0,   2, Doubles, "Double-precision floating point")
+SHADER_FEATURE_FLAG(1,   4, ComputeShadersPlusRawAndStructuredBuffers, "Raw and Structured buffers")
+SHADER_FEATURE_FLAG(2,  16, UAVsAtEveryStage, "UAVs at every shader stage")
+SHADER_FEATURE_FLAG(3,  15, Max64UAVs, "64 UAV slots")
+SHADER_FEATURE_FLAG(4,   5, MinimumPrecision, "Minimum-precision data types")
+SHADER_FEATURE_FLAG(5,   6, DX11_1_DoubleExtensions, "Double-precision extensions for 11.1")
+SHADER_FEATURE_FLAG(6,   7, DX11_1_ShaderExtensions, "Shader extensions for 11.1")
+SHADER_FEATURE_FLAG(7,  14, LEVEL9ComparisonFiltering, "Comparison filtering for feature level 9")
+SHADER_FEATURE_FLAG(8,  12, TiledResources, "Tiled resources")
+SHADER_FEATURE_FLAG(9,  11, StencilRef, "PS Output Stencil Ref")
+SHADER_FEATURE_FLAG(10, 10, InnerCoverage, "PS Inner Coverage")
+SHADER_FEATURE_FLAG(11, 13, TypedUAVLoadAdditionalFormats, "Typed UAV Load Additional Formats")
+SHADER_FEATURE_FLAG(12, 18, ROVs, "Raster Ordered UAVs")
+SHADER_FEATURE_FLAG(13,  9, ViewportAndRTArrayIndexFromAnyShaderFeedingRasterizer, "SV_RenderTargetArrayIndex or SV_ViewportArrayIndex from any shader feeding rasterizer")
+SHADER_FEATURE_FLAG(14, 19, WaveOps, "Wave level operations")
+SHADER_FEATURE_FLAG(15, 20, Int64Ops, "64-Bit integer")
+SHADER_FEATURE_FLAG(16, 21, ViewID, "View Instancing")
+SHADER_FEATURE_FLAG(17, 22, Barycentrics, "Barycentrics")
+SHADER_FEATURE_FLAG(18, 23, NativeLowPrecision, "Use native low precision")
----------------
tex3d wrote:

`NativeLowPrecision`, and `MinimumPrecision`, are not 1:1 mappings between module flags and feature flags.  DxilModuleFlags has `LowPrecisionPresent` and `UseNativeLowPrecision`, which are used together to set the feature flags.  Neither are set if `LowPrecisionPresent` is unset, and one is set if `LowPrecisionPresent` is set, depending on the state of `UseNativeLowPrecision`.

DXC's code:
```cpp
  Flags |= m_bLowPrecisionPresent && !m_bUseNativeLowPrecision
               ? hlsl::DXIL::ShaderFeatureInfo_MinimumPrecision
               : 0;
  Flags |= m_bLowPrecisionPresent && m_bUseNativeLowPrecision
               ? hlsl::DXIL::ShaderFeatureInfo_NativeLowPrecision
               : 0;
```

https://github.com/llvm/llvm-project/pull/83217