Restrict to translate uniform block to StructuredBuffer

include/GLSLANG/ShaderLang.h

@@ -26,7 +26,7 @@
 
 // Version number for shader translation API.
 // It is incremented every time the API changes.
-#define ANGLE_SH_VERSION 236
+#define ANGLE_SH_VERSION 237
 
 enum ShShaderSpec
 {
@@ -315,9 +315,8 @@ const ShCompileOptions SH_ADD_BASE_VERTEX_TO_VERTEX_ID = UINT64_C(1) << 48;
 // This works around the dynamic lvalue indexing of swizzled vectors on various platforms.
 const ShCompileOptions SH_REMOVE_DYNAMIC_INDEXING_OF_SWIZZLED_VECTOR = UINT64_C(1) << 49;
 
-// This flag works a driver bug that fails to allocate ShaderResourceView for StructuredBuffer
-// on Windows 7 and earlier.
-const ShCompileOptions SH_DONT_TRANSLATE_UNIFORM_BLOCK_TO_STRUCTUREDBUFFER = UINT64_C(1) << 50;
+// This flag works around a slow fxc compile performance issue with dynamic uniform indexing.
+const ShCompileOptions SH_ALLOW_TRANSLATE_UNIFORM_BLOCK_TO_STRUCTUREDBUFFER = UINT64_C(1) << 50;
 
 // This flag indicates whether Bresenham line raster emulation code should be generated.  This
 // emulation is necessary if the backend uses a differnet algorithm to draw lines.  Currently only

include/platform/FeaturesD3D.h

@@ -207,11 +207,13 @@ struct FeaturesD3D : FeatureSetBase
         "Some drivers corrupt texture data when clearing for robust resource initialization.",
         &members, "http://crbug.com/941620"};
 
-    // Don't translate uniform block to StructuredBuffer on Windows 7 and earlier. This is targeted
-    // to work around a bug that fails to allocate ShaderResourceView for StructuredBuffer.
-    Feature dontTranslateUniformBlockToStructuredBuffer = {
-        "dont_translate_uniform_block_to_structured_buffer", FeatureCategory::D3DWorkarounds,
-        "Fails to allocate ShaderResourceView for StructuredBuffer on some drivers", &members};
+    // Allow translating uniform block to StructuredBuffer. This is targeted to work around a slow
+    // fxc compile performance issue with dynamic uniform indexing. http://anglebug.com/3682
+    Feature allowTranslateUniformBlockToStructuredBuffer = {
+        "allow_translate_uniform_block_to_structured_buffer", FeatureCategory::D3DWorkarounds,
+        "There is a slow fxc compile performance issue with dynamic uniform indexing if "
+        "translating a uniform block with a large array member to cbuffer.",
+        &members, "http://anglebug.com/3682"};
 };
 
 inline FeaturesD3D::FeaturesD3D()  = default;

src/compiler.gni

@@ -148,6 +148,8 @@ angle_translator_sources = [
   "src/compiler/translator/tree_ops/PruneNoOps.h",
   "src/compiler/translator/tree_ops/RecordConstantPrecision.cpp",
   "src/compiler/translator/tree_ops/RecordConstantPrecision.h",
+  "src/compiler/translator/tree_ops/RecordUniformBlocksTranslatedToStructuredBuffers.cpp",
+  "src/compiler/translator/tree_ops/RecordUniformBlocksTranslatedToStructuredBuffers.h",
   "src/compiler/translator/tree_ops/RegenerateStructNames.cpp",
   "src/compiler/translator/tree_ops/RegenerateStructNames.h",
   "src/compiler/translator/tree_ops/RemoveArrayLengthMethod.cpp",

src/compiler/translator/OutputHLSL.cpp

@@ -297,20 +297,22 @@ const TConstantUnion *OutputHLSL::writeConstantUnionArray(TInfoSinkBase &out,
     return constUnionIterated;
 }
 
-OutputHLSL::OutputHLSL(sh::GLenum shaderType,
-                       ShShaderSpec shaderSpec,
-                       int shaderVersion,
-                       const TExtensionBehavior &extensionBehavior,
-                       const char *sourcePath,
-                       ShShaderOutput outputType,
-                       int numRenderTargets,
-                       int maxDualSourceDrawBuffers,
-                       const std::vector<ShaderVariable> &uniforms,
-                       ShCompileOptions compileOptions,
-                       sh::WorkGroupSize workGroupSize,
-                       TSymbolTable *symbolTable,
-                       PerformanceDiagnostics *perfDiagnostics,
-                       const std::vector<InterfaceBlock> &shaderStorageBlocks)
+OutputHLSL::OutputHLSL(
+    sh::GLenum shaderType,
+    ShShaderSpec shaderSpec,
+    int shaderVersion,
+    const TExtensionBehavior &extensionBehavior,
+    const char *sourcePath,
+    ShShaderOutput outputType,
+    int numRenderTargets,
+    int maxDualSourceDrawBuffers,
+    const std::vector<ShaderVariable> &uniforms,
+    ShCompileOptions compileOptions,
+    sh::WorkGroupSize workGroupSize,
+    TSymbolTable *symbolTable,
+    PerformanceDiagnostics *perfDiagnostics,
+    const std::map<int, const TInterfaceBlock *> &uniformBlocksTranslatedToStructuredBuffers,
+    const std::vector<InterfaceBlock> &shaderStorageBlocks)
     : TIntermTraverser(true, true, true, symbolTable),
       mShaderType(shaderType),
       mShaderSpec(shaderSpec),
@@ -321,6 +323,7 @@ OutputHLSL::OutputHLSL(sh::GLenum shaderType,
       mCompileOptions(compileOptions),
       mInsideFunction(false),
       mInsideMain(false),
+      mUniformBlocksTranslatedToStructuredBuffers(uniformBlocksTranslatedToStructuredBuffers),
       mNumRenderTargets(numRenderTargets),
       mMaxDualSourceDrawBuffers(maxDualSourceDrawBuffers),
       mCurrentFunctionMetadata(nullptr),
@@ -371,8 +374,7 @@ OutputHLSL::OutputHLSL(sh::GLenum shaderType,
 
     unsigned int firstUniformRegister =
         ((compileOptions & SH_SKIP_D3D_CONSTANT_REGISTER_ZERO) != 0) ? 1u : 0u;
-    mResourcesHLSL = new ResourcesHLSL(mStructureHLSL, outputType, compileOptions, uniforms,
-                                       firstUniformRegister);
+    mResourcesHLSL = new ResourcesHLSL(mStructureHLSL, outputType, uniforms, firstUniformRegister);
 
     if (mOutputType == SH_HLSL_3_0_OUTPUT)
     {
@@ -659,7 +661,8 @@ void OutputHLSL::header(TInfoSinkBase &out,
     out << mStructureHLSL->structsHeader();
 
     mResourcesHLSL->uniformsHeader(out, mOutputType, mReferencedUniforms, mSymbolTable);
-    out << mResourcesHLSL->uniformBlocksHeader(mReferencedUniformBlocks);
+    out << mResourcesHLSL->uniformBlocksHeader(mReferencedUniformBlocks,
+                                               mUniformBlocksTranslatedToStructuredBuffers);
     mSSBOOutputHLSL->writeShaderStorageBlocksHeader(out);
 
     if (!mEqualityFunctions.empty())
@@ -1647,14 +1650,18 @@ bool OutputHLSL::visitBinary(Visit visit, TIntermBinary *node)
                 {
                     const TInterfaceBlock *interfaceBlock =
                         GetInterfaceBlockOfUniformBlockNearestIndexOperator(node->getLeft());
-                    if (interfaceBlock &&
-                        mResourcesHLSL->shouldTranslateUniformBlockToStructuredBuffer(
-                            *interfaceBlock))
+                    if (interfaceBlock && mUniformBlocksTranslatedToStructuredBuffers.count(
+                                              interfaceBlock->uniqueId().get()) != 0)
                     {
-                        const TField *field = interfaceBlock->fields()[0];
-                        if (field->type()->isMatrix())
+                        // If the uniform block member's type is not structure, we had explicitly
+                        // packed the member into a structure, so need to add an operator of field
+                        // slection.
+                        const TField *field    = interfaceBlock->fields()[0];
+                        const TType *fieldType = field->type();
+                        if (fieldType->isMatrix() || fieldType->isVectorArray() ||
+                            fieldType->isScalarArray())
                         {
-                            out << "._matrix_" << Decorate(field->name());
+                            out << "." << Decorate(field->name());
                         }
                     }
                 }
@@ -1678,14 +1685,18 @@ bool OutputHLSL::visitBinary(Visit visit, TIntermBinary *node)
                 {
                     const TInterfaceBlock *interfaceBlock =
                         GetInterfaceBlockOfUniformBlockNearestIndexOperator(node->getLeft());
-                    if (interfaceBlock &&
-                        mResourcesHLSL->shouldTranslateUniformBlockToStructuredBuffer(
-                            *interfaceBlock))
+                    if (interfaceBlock && mUniformBlocksTranslatedToStructuredBuffers.count(
+                                              interfaceBlock->uniqueId().get()) != 0)
                     {
-                        const TField *field = interfaceBlock->fields()[0];
-                        if (field->type()->isMatrix())
+                        // If the uniform block member's type is not structure, we had explicitly
+                        // packed the member into a structure, so need to add an operator of field
+                        // slection.
+                        const TField *field    = interfaceBlock->fields()[0];
+                        const TType *fieldType = field->type();
+                        if (fieldType->isMatrix() || fieldType->isVectorArray() ||
+                            fieldType->isScalarArray())
                         {
-                            out << "._matrix_" << Decorate(field->name());
+                            out << "." << Decorate(field->name());
                         }
                     }
                 }
@@ -1746,8 +1757,8 @@ bool OutputHLSL::visitBinary(Visit visit, TIntermBinary *node)
                     node->getLeft()->getType().getInterfaceBlock();
                 const TIntermConstantUnion *index = node->getRight()->getAsConstantUnion();
                 const TField *field               = interfaceBlock->fields()[index->getIConst(0)];
-                if (structInStd140UniformBlock ||
-                    mResourcesHLSL->shouldTranslateUniformBlockToStructuredBuffer(*interfaceBlock))
+                if (structInStd140UniformBlock || mUniformBlocksTranslatedToStructuredBuffers.count(
+                                                      interfaceBlock->uniqueId().get()) != 0)
                 {
                     out << "_";
                 }

src/compiler/translator/OutputHLSL.h

@@ -37,20 +37,22 @@ using ReferencedVariables = std::map<int, const TVariable *>;
 class OutputHLSL : public TIntermTraverser
 {
   public:
-    OutputHLSL(sh::GLenum shaderType,
-               ShShaderSpec shaderSpec,
-               int shaderVersion,
-               const TExtensionBehavior &extensionBehavior,
-               const char *sourcePath,
-               ShShaderOutput outputType,
-               int numRenderTargets,
-               int maxDualSourceDrawBuffers,
-               const std::vector<ShaderVariable> &uniforms,
-               ShCompileOptions compileOptions,
-               sh::WorkGroupSize workGroupSize,
-               TSymbolTable *symbolTable,
-               PerformanceDiagnostics *perfDiagnostics,
-               const std::vector<InterfaceBlock> &shaderStorageBlocks);
+    OutputHLSL(
+        sh::GLenum shaderType,
+        ShShaderSpec shaderSpec,
+        int shaderVersion,
+        const TExtensionBehavior &extensionBehavior,
+        const char *sourcePath,
+        ShShaderOutput outputType,
+        int numRenderTargets,
+        int maxDualSourceDrawBuffers,
+        const std::vector<ShaderVariable> &uniforms,
+        ShCompileOptions compileOptions,
+        sh::WorkGroupSize workGroupSize,
+        TSymbolTable *symbolTable,
+        PerformanceDiagnostics *perfDiagnostics,
+        const std::map<int, const TInterfaceBlock *> &uniformBlocksTranslatedToStructuredBuffers,
+        const std::vector<InterfaceBlock> &shaderStorageBlocks);
 
     ~OutputHLSL() override;
 
@@ -179,6 +181,8 @@ class OutputHLSL : public TIntermTraverser
     // Indexed by block id, not instance id.
     ReferencedInterfaceBlocks mReferencedUniformBlocks;
 
+    std::map<int, const TInterfaceBlock *> mUniformBlocksTranslatedToStructuredBuffers;
+
     ReferencedVariables mReferencedAttributes;
     ReferencedVariables mReferencedVaryings;
     ReferencedVariables mReferencedOutputVariables;

src/compiler/translator/ResourcesHLSL.cpp

@@ -24,11 +24,6 @@ namespace
 {
 
 constexpr const ImmutableString kAngleDecorString("angle_");
-// D3D11_COMMONSHADER_INPUT_RESOURCE_SLOT_COUNT = 128;
-const unsigned int kMaxInputResourceSlotCount = 128u;
-// If uniform block member's array size is larger than kMinArraySizeUseStructuredBuffer,
-// then we translate uniform block to StructuredBuffer for compiling performance.
-const unsigned int kMinArraySizeUseStructuredBuffer = 50u;
 
 static const char *UniformRegisterPrefix(const TType &type)
 {
@@ -104,46 +99,72 @@ void OutputUniformIndexArrayInitializer(TInfoSinkBase &out,
     out << "}";
 }
 
-// Check whether all fields match std140 storage layout, and do not need to add paddings
-// when translating std140 uniform block to StructuredBuffer.
-static bool ShouldPadUniformBlockMemberForStructuredBuffer(const TType &type)
+static TString InterfaceBlockScalarVectorFieldPaddingString(const TType &type)
 {
-    const TStructure *structure = type.getStruct();
-    if (structure)
+    switch (type.getBasicType())
     {
-        const TFieldList &fields = structure->fields();
-        for (size_t i = 0; i < fields.size(); i++)
-        {
-            if (ShouldPadUniformBlockMemberForStructuredBuffer(*fields[i]->type()))
+        case EbtFloat:
+            switch (type.getNominalSize())
             {
-                return true;
+                case 1:
+                    return "float3 padding;";
+                case 2:
+                    return "float2 padding;";
+                case 3:
+                    return "float padding;";
+                default:
+                    break;
             }
-        }
-        return false;
-    }
-    else if (type.isMatrix())
-    {
-        if ((type.getLayoutQualifier().matrixPacking != EmpRowMajor && type.getRows() == 4) ||
-            (type.getLayoutQualifier().matrixPacking == EmpRowMajor && type.getCols() == 4))
-        {
-            return false;
-        }
-    }
-    else
-    {
-        if (type.isVector() && type.getNominalSize() == 4)
-        {
-            return false;
-        }
+            break;
+        case EbtInt:
+            switch (type.getNominalSize())
+            {
+                case 1:
+                    return "int3 padding;";
+                case 2:
+                    return "int2 padding;";
+                case 3:
+                    return "int padding";
+                default:
+                    break;
+            }
+            break;
+        case EbtUInt:
+            switch (type.getNominalSize())
+            {
+                case 1:
+                    return "uint3 padding;";
+                case 2:
+                    return "uint2 padding;";
+                case 3:
+                    return "uint padding;";
+                default:
+                    break;
+            }
+            break;
+        case EbtBool:
+            switch (type.getNominalSize())
+            {
+                case 1:
+                    return "bool3 padding;";
+                case 2:
+                    return "bool2 padding;";
+                case 3:
+                    return "bool padding;";
+                default:
+                    break;
+            }
+            break;
+        default:
+            break;
     }
-
-    return true;
+    return "";
 }
+
 }  // anonymous namespace
 
 ResourcesHLSL::ResourcesHLSL(StructureHLSL *structureHLSL,
                              ShShaderOutput outputType,
-                             ShCompileOptions compileOptions,
                              const std::vector<ShaderVariable> &uniforms,
                              unsigned int firstUniformRegister)
     : mUniformRegister(firstUniformRegister),
@@ -153,7 +174,6 @@ ResourcesHLSL::ResourcesHLSL(StructureHLSL *structureHLSL,
       mSamplerCount(0),
       mStructureHLSL(structureHLSL),
       mOutputType(outputType),
-      mCompileOptions(compileOptions),
       mUniforms(uniforms)
 {}
 
@@ -676,7 +696,8 @@ void ResourcesHLSL::imageMetadataUniforms(TInfoSinkBase &out, unsigned int regIn
 }
 
 TString ResourcesHLSL::uniformBlocksHeader(
-    const ReferencedInterfaceBlocks &referencedInterfaceBlocks)
+    const ReferencedInterfaceBlocks &referencedInterfaceBlocks,
+    const std::map<int, const TInterfaceBlock *> &uniformBlockTranslatedToStructuredBuffer)
 {
     TString interfaceBlocks;
 
@@ -691,7 +712,7 @@ TString ResourcesHLSL::uniformBlocksHeader(
 
         // In order to avoid compile performance issue, translate uniform block to structured
         // buffer. anglebug.com/3682.
-        if (shouldTranslateUniformBlockToStructuredBuffer(interfaceBlock))
+        if (uniformBlockTranslatedToStructuredBuffer.count(interfaceBlock.uniqueId().get()) != 0)
         {
             unsigned int structuredBufferRegister = mSRVRegister;
             if (instanceVariable != nullptr && instanceVariable->getType().isArray())
@@ -820,10 +841,22 @@ TString ResourcesHLSL::uniformBlockWithOneLargeArrayMemberString(
     {
         if (arrayIndex == GL_INVALID_INDEX || arrayIndex == 0)
         {
-            hlsl += "struct matrix" + Decorate(field.name()) + " { " + typeString + " _matrix_" +
+            hlsl += "struct pack" + Decorate(interfaceBlock.name()) + " { " + typeString + " " +
                     Decorate(field.name()) + "; };\n";
         }
-        typeString = "matrix" + Decorate(field.name());
+        typeString = "pack" + Decorate(interfaceBlock.name());
+    }
+    else if (fieldType.isVectorArray() || fieldType.isScalarArray())
+    {
+        // If the member is an array of scalars or vectors, std140 rules require the base array
+        // stride are rounded up to the base alignment of a vec4.
+        if (arrayIndex == GL_INVALID_INDEX || arrayIndex == 0)
+        {
+            hlsl += "struct pack" + Decorate(interfaceBlock.name()) + " { " + typeString + " " +
+                    Decorate(field.name()) + ";\n";
+            hlsl += InterfaceBlockScalarVectorFieldPaddingString(fieldType) + " };\n";
+        }
+        typeString = "pack" + Decorate(interfaceBlock.name());
     }
 
     if (instanceVariable != nullptr)
@@ -890,7 +923,7 @@ TString ResourcesHLSL::uniformBlockMembersString(const TInterfaceBlock &interfac
         if (blockStorage == EbsStd140)
         {
             // 2 and 3 component vector types in some cases need pre-padding
-            hlsl += padHelper.prePaddingString(fieldType);
+            hlsl += padHelper.prePaddingString(fieldType, false);
         }
 
         hlsl += "    " + InterfaceBlockFieldTypeString(field, blockStorage, false) + " " +
@@ -918,18 +951,4 @@ TString ResourcesHLSL::uniformBlockStructString(const TInterfaceBlock &interface
            "{\n" +
            uniformBlockMembersString(interfaceBlock, blockStorage) + "};\n\n";
 }
-
-bool ResourcesHLSL::shouldTranslateUniformBlockToStructuredBuffer(
-    const TInterfaceBlock &interfaceBlock)
-{
-    const TType &fieldType = *interfaceBlock.fields()[0]->type();
-    // Restrict field and sub-fields types match std140 storage layout rules, even the uniform
-    // does not use std140 qualifier.
-    bool shouldPadUniformBlockMember = ShouldPadUniformBlockMemberForStructuredBuffer(fieldType);
-
-    return (mCompileOptions & SH_DONT_TRANSLATE_UNIFORM_BLOCK_TO_STRUCTUREDBUFFER) == 0 &&
-           mSRVRegister < kMaxInputResourceSlotCount && interfaceBlock.fields().size() == 1u &&
-           !shouldPadUniformBlockMember && fieldType.getNumArraySizes() == 1u &&
-           fieldType.getOutermostArraySize() >= kMinArraySizeUseStructuredBuffer;
-}
 }  // namespace sh

src/compiler/translator/ResourcesHLSL.h

@@ -24,7 +24,6 @@ class ResourcesHLSL : angle::NonCopyable
   public:
     ResourcesHLSL(StructureHLSL *structureHLSL,
                   ShShaderOutput outputType,
-                  ShCompileOptions compileOptions,
                   const std::vector<ShaderVariable> &uniforms,
                   unsigned int firstUniformRegister);
 
@@ -39,7 +38,9 @@ class ResourcesHLSL : angle::NonCopyable
     void samplerMetadataUniforms(TInfoSinkBase &out, unsigned int regIndex);
     unsigned int getSamplerCount() const { return mSamplerCount; }
     void imageMetadataUniforms(TInfoSinkBase &out, unsigned int regIndex);
-    TString uniformBlocksHeader(const ReferencedInterfaceBlocks &referencedInterfaceBlocks);
+    TString uniformBlocksHeader(
+        const ReferencedInterfaceBlocks &referencedInterfaceBlocks,
+        const std::map<int, const TInterfaceBlock *> &uniformBlockTranslatedToStructuredBuffer);
     TString shaderStorageBlocksHeader(const ReferencedInterfaceBlocks &referencedInterfaceBlocks);
 
     // Used for direct index references
@@ -68,7 +69,6 @@ class ResourcesHLSL : angle::NonCopyable
 
     unsigned int getReadonlyImage2DRegisterIndex() const { return mReadonlyImage2DRegisterIndex; }
     unsigned int getImage2DRegisterIndex() const { return mImage2DRegisterIndex; }
-    bool shouldTranslateUniformBlockToStructuredBuffer(const TInterfaceBlock &interfaceBlock);
 
   private:
     TString uniformBlockString(const TInterfaceBlock &interfaceBlock,
@@ -138,7 +138,6 @@ class ResourcesHLSL : angle::NonCopyable
     unsigned int mImageCount;
     StructureHLSL *mStructureHLSL;
     ShShaderOutput mOutputType;
-    ShCompileOptions mCompileOptions;
 
     const std::vector<ShaderVariable> &mUniforms;
     std::map<std::string, unsigned int> mUniformBlockRegisterMap;

src/compiler/translator/StructureHLSL.cpp

@@ -23,13 +23,13 @@ namespace
 TString Define(const TStructure &structure,
                bool useHLSLRowMajorPacking,
                bool useStd140Packing,
-               bool forcePackingEnd,
+               bool forcePadding,
                Std140PaddingHelper *padHelper)
 {
     const TFieldList &fields    = structure.fields();
     const bool isNameless       = (structure.symbolType() == SymbolType::Empty);
     const TString &structName   = QualifiedStructNameString(structure, useHLSLRowMajorPacking,
-                                                          useStd140Packing, forcePackingEnd);
+                                                          useStd140Packing, forcePadding);
     const TString declareString = (isNameless ? "struct" : "struct " + structName);
 
     TString string;
@@ -52,7 +52,8 @@ TString Define(const TStructure &structure,
 
             if (padHelper)
             {
-                string += padHelper->prePaddingString(fieldType);
+                string += padHelper->prePaddingString(
+                    fieldType, (memberSize != fields.size() - 1) && forcePadding);
             }
 
             string += "    " + fieldTypeString + " " + DecorateField(field->name(), structure) +
@@ -61,7 +62,7 @@ TString Define(const TStructure &structure,
             if (padHelper)
             {
                 string += padHelper->postPaddingString(fieldType, useHLSLRowMajorPacking,
-                                                       memberSize == 0 && forcePackingEnd);
+                                                       memberSize == 0 && forcePadding);
             }
         }
     }
@@ -118,7 +119,7 @@ TString Std140PaddingHelper::next()
     return str(value);
 }
 
-int Std140PaddingHelper::prePadding(const TType &type)
+int Std140PaddingHelper::prePadding(const TType &type, bool forcePadding)
 {
     if (type.getBasicType() == EbtStruct || type.isMatrix() || type.isArray())
     {
@@ -139,9 +140,20 @@ int Std140PaddingHelper::prePadding(const TType &type)
 
     if (mElementIndex + numComponents > 4)
     {
-        // no padding needed, HLSL will align the field to a new register
-        mElementIndex = numComponents;
-        return 0;
+        if (forcePadding)
+        {
+            // If this structure will be used as HLSL StructuredBuffer member's type, we should add
+            // padding between the structure's members to follow the std140 rules manually.
+            const int forcePaddingCount = 4 - mElementIndex;
+            mElementIndex               = numComponents;
+            return forcePaddingCount;
+        }
+        else
+        {
+            // no padding needed, HLSL will align the field to a new register
+            mElementIndex = numComponents;
+            return 0;
+        }
     }
 
     const int alignment     = numComponents == 3 ? 4 : numComponents;
@@ -155,9 +167,9 @@ int Std140PaddingHelper::prePadding(const TType &type)
     return paddingCount;
 }
 
-TString Std140PaddingHelper::prePaddingString(const TType &type)
+TString Std140PaddingHelper::prePaddingString(const TType &type, bool forcePadding)
 {
-    int paddingCount = prePadding(type);
+    int paddingCount = prePadding(type, forcePadding);
 
     TString padding;
 
@@ -173,8 +185,21 @@ TString Std140PaddingHelper::postPaddingString(const TType &type,
                                                bool useHLSLRowMajorPacking,
                                                bool forcePadding)
 {
-    if (!forcePadding && !type.isMatrix() && !type.isArray() && type.getBasicType() != EbtStruct)
+    if (!type.isMatrix() && !type.isArray() && type.getBasicType() != EbtStruct)
     {
+        if (forcePadding)
+        {
+            // If this structure will be used as HLSL StructuredBuffer member's type, we
+            // should force to pad the end of the structure to follow the std140 rules.
+            TString forcePaddingStr;
+            const int paddingOffset = mElementIndex % 4;
+            const int paddingCount  = paddingOffset != 0 ? (4 - paddingOffset) : 0;
+            for (int paddingIndex = 0; paddingIndex < paddingCount; paddingIndex++)
+            {
+                forcePaddingStr += "    float pad_" + next() + ";\n";
+            }
+            return forcePaddingStr;
+        }
         return "";
     }
 
@@ -229,12 +254,12 @@ Std140PaddingHelper StructureHLSL::getPaddingHelper()
 TString StructureHLSL::defineQualified(const TStructure &structure,
                                        bool useHLSLRowMajorPacking,
                                        bool useStd140Packing,
-                                       bool forcePackingEnd)
+                                       bool forcePadding)
 {
     if (useStd140Packing)
     {
         Std140PaddingHelper padHelper = getPaddingHelper();
-        return Define(structure, useHLSLRowMajorPacking, useStd140Packing, forcePackingEnd,
+        return Define(structure, useHLSLRowMajorPacking, useStd140Packing, forcePadding,
                       &padHelper);
     }
     else
@@ -282,19 +307,19 @@ StructureHLSL::DefinedStructs::iterator StructureHLSL::defineVariants(const TStr
                                    defineQualified(structure, true, true, false) +
                                    "#pragma pack_matrix(column_major)\n";
 
-    // Must use packed structure for StructuredBuffer element type, if qualifier of structure is
-    // std140.
-    TString std140PackingEndString         = defineQualified(structure, false, true, true);
-    TString std140RowMajorPackEndingString = "#pragma pack_matrix(row_major)\n" +
-                                             defineQualified(structure, true, true, true) +
-                                             "#pragma pack_matrix(column_major)\n";
+    // Must force to pad the structure's elements for StructuredBuffer's element type, if qualifier
+    // of structure is std140.
+    TString std140ForcePaddingString         = defineQualified(structure, false, true, true);
+    TString std140RowMajorForcePaddingString = "#pragma pack_matrix(row_major)\n" +
+                                               defineQualified(structure, true, true, true) +
+                                               "#pragma pack_matrix(column_major)\n";
 
     mStructDeclarations.push_back(structString);
     mStructDeclarations.push_back(rowMajorString);
     mStructDeclarations.push_back(std140String);
     mStructDeclarations.push_back(std140RowMajorString);
-    mStructDeclarations.push_back(std140PackingEndString);
-    mStructDeclarations.push_back(std140RowMajorPackEndingString);
+    mStructDeclarations.push_back(std140ForcePaddingString);
+    mStructDeclarations.push_back(std140RowMajorForcePaddingString);
     return addedStruct;
 }
 
@@ -596,7 +621,7 @@ void StructureHLSL::storeStd140ElementIndex(const TStructure &structure,
 
     for (const TField *field : fields)
     {
-        padHelper.prePadding(*field->type());
+        padHelper.prePadding(*field->type(), false);
     }
 
     // Add remaining element index to the global map, for use with nested structs in standard

src/compiler/translator/StructureHLSL.h

@@ -32,8 +32,8 @@ class Std140PaddingHelper
     Std140PaddingHelper &operator=(const Std140PaddingHelper &other);
 
     int elementIndex() const { return mElementIndex; }
-    int prePadding(const TType &type);
-    TString prePaddingString(const TType &type);
+    int prePadding(const TType &type, bool forcePadding);
+    TString prePaddingString(const TType &type, bool forcePadding);
     TString postPaddingString(const TType &type, bool useHLSLRowMajorPacking, bool forcePadding);
 
   private:

src/compiler/translator/TranslatorHLSL.cpp

@@ -12,6 +12,7 @@
 #include "compiler/translator/tree_ops/BreakVariableAliasingInInnerLoops.h"
 #include "compiler/translator/tree_ops/ExpandIntegerPowExpressions.h"
 #include "compiler/translator/tree_ops/PruneEmptyCases.h"
+#include "compiler/translator/tree_ops/RecordUniformBlocksTranslatedToStructuredBuffers.h"
 #include "compiler/translator/tree_ops/RemoveDynamicIndexing.h"
 #include "compiler/translator/tree_ops/RewriteAtomicFunctionExpressions.h"
 #include "compiler/translator/tree_ops/RewriteElseBlocks.h"
@@ -183,11 +184,25 @@ bool TranslatorHLSL::translate(TIntermBlock *root,
         }
     }
 
-    sh::OutputHLSL outputHLSL(getShaderType(), getShaderSpec(), getShaderVersion(),
-                              getExtensionBehavior(), getSourcePath(), getOutputType(),
-                              numRenderTargets, maxDualSourceDrawBuffers, getUniforms(),
-                              compileOptions, getComputeShaderLocalSize(), &getSymbolTable(),
-                              perfDiagnostics, mShaderStorageBlocks);
+    mUniformBlocksTranslatedToStructuredBuffers.clear();
+    // In order to get the exact maximum of slots are available for shader resources, which would
+    // been bound with StructuredBuffer, we only translate uniform block with a large array member
+    // into StructuredBuffer when shader version is 300.
+    if (getShaderVersion() == 300 &&
+        (compileOptions & SH_ALLOW_TRANSLATE_UNIFORM_BLOCK_TO_STRUCTUREDBUFFER) != 0)
+    {
+        if (!sh::RecordUniformBlocksTranslatedToStructuredBuffers(
+                root, mUniformBlocksTranslatedToStructuredBuffers))
+        {
+            return false;
+        }
+    }
+
+    sh::OutputHLSL outputHLSL(
+        getShaderType(), getShaderSpec(), getShaderVersion(), getExtensionBehavior(),
+        getSourcePath(), getOutputType(), numRenderTargets, maxDualSourceDrawBuffers, getUniforms(),
+        compileOptions, getComputeShaderLocalSize(), &getSymbolTable(), perfDiagnostics,
+        mUniformBlocksTranslatedToStructuredBuffers, mShaderStorageBlocks);
 
     outputHLSL.output(root, getInfoSink().obj);
 

src/compiler/translator/TranslatorHLSL.h

@@ -46,6 +46,7 @@ class TranslatorHLSL : public TCompiler
     unsigned int mReadonlyImage2DRegisterIndex;
     unsigned int mImage2DRegisterIndex;
     std::set<std::string> mUsedImage2DFunctionNames;
+    std::map<int, const TInterfaceBlock *> mUniformBlocksTranslatedToStructuredBuffers;
 };
 
 }  // namespace sh

src/compiler/translator/Types.h

@@ -231,10 +231,15 @@ class TType
     bool isInterfaceBlock() const { return type == EbtInterfaceBlock; }
 
     bool isVector() const { return primarySize > 1 && secondarySize == 1; }
+    bool isVectorArray() const { return primarySize > 1 && secondarySize == 1 && isArray(); }
     bool isScalar() const
     {
         return primarySize == 1 && secondarySize == 1 && !mStructure && !isArray();
     }
+    bool isScalarArray() const
+    {
+        return primarySize == 1 && secondarySize == 1 && !mStructure && isArray();
+    }
     bool isScalarFloat() const { return isScalar() && type == EbtFloat; }
     bool isScalarInt() const { return isScalar() && (type == EbtInt || type == EbtUInt); }
 

src/compiler/translator/UtilsHLSL.cpp

@@ -1009,7 +1009,7 @@ TString StructNameString(const TStructure &structure)
 TString QualifiedStructNameString(const TStructure &structure,
                                   bool useHLSLRowMajorPacking,
                                   bool useStd140Packing,
-                                  bool forcePackingEnd)
+                                  bool forcePadding)
 {
     if (structure.symbolType() == SymbolType::Empty)
     {
@@ -1031,9 +1031,9 @@ TString QualifiedStructNameString(const TStructure &structure,
         prefix += "rm_";
     }
 
-    if (forcePackingEnd)
+    if (forcePadding)
     {
-        prefix += "pe_";
+        prefix += "fp_";
     }
 
     return prefix + StructNameString(structure);

src/compiler/translator/tree_ops/RecordUniformBlocksTranslatedToStructuredBuffers.h

+//
+// Copyright 2020 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// RecordUniformBlocksTranslatedToStructuredBuffers.h:
+// Collect all uniform blocks which will been translated to StructuredBuffers on Direct3D
+// backend.
+//
+
+#ifndef COMPILER_TRANSLATOR_TREEOPS_RECORDUNIFORMBLOCKSTRANSLATEDTOSTRUCTUREDBUFFERS_H_
+#define COMPILER_TRANSLATOR_TREEOPS_RECORDUNIFORMBLOCKSTRANSLATEDTOSTRUCTUREDBUFFERS_H_
+
+#include "compiler/translator/IntermNode.h"
+
+namespace sh
+{
+class TIntermNode;
+
+ANGLE_NO_DISCARD bool RecordUniformBlocksTranslatedToStructuredBuffers(
+    TIntermNode *root,
+    std::map<int, const TInterfaceBlock *> &uniformBlockTranslatedToStructuredBuffer);
+}  // namespace sh
+
+#endif  // COMPILER_TRANSLATOR_TREEOPS_RECORDACCESSUNIFORMBLOCKENTIREARRAYMEMBER_H_

src/libANGLE/renderer/d3d/ShaderD3D.cpp

@@ -125,9 +125,9 @@ ShaderD3D::ShaderD3D(const gl::ShaderState &state,
     {
         mAdditionalOptions |= SH_FORCE_ATOMIC_VALUE_RESOLUTION;
     }
-    if (features.dontTranslateUniformBlockToStructuredBuffer.enabled)
+    if (features.allowTranslateUniformBlockToStructuredBuffer.enabled)
     {
-        mAdditionalOptions |= SH_DONT_TRANSLATE_UNIFORM_BLOCK_TO_STRUCTUREDBUFFER;
+        mAdditionalOptions |= SH_ALLOW_TRANSLATE_UNIFORM_BLOCK_TO_STRUCTUREDBUFFER;
     }
     if (extensions.multiview || extensions.multiview2)
     {

src/libANGLE/renderer/d3d/d3d11/renderer11_utils.cpp

@@ -2482,9 +2482,10 @@ void InitializeFeatures(const Renderer11DeviceCaps &deviceCaps,
     // Intel, they've been blocklisted to the DX9 runtime.
     ANGLE_FEATURE_CONDITION(features, allowClearForRobustResourceInit, true);
 
-    // There is an issue(crbug.com/1112112) when translating uniform block to StructuredBuffer,
-    // so disable this feature temporarily.
-    ANGLE_FEATURE_CONDITION(features, dontTranslateUniformBlockToStructuredBuffer, true);
+    // Allow translating uniform block to StructuredBuffer on Windows 10. This is targeted
+    // to work around a slow fxc compile performance issue with dynamic uniform indexing.
+    ANGLE_FEATURE_CONDITION(features, allowTranslateUniformBlockToStructuredBuffer,
+                            IsWin10OrGreater());
 
     // Call platform hooks for testing overrides.
     auto *platform = ANGLEPlatformCurrent();

src/libANGLE/renderer/driver_utils.cpp

@@ -21,6 +21,10 @@
 #    include <sys/utsname.h>
 #endif
 
+#if defined(ANGLE_PLATFORM_WINDOWS)
+#    include <versionhelpers.h>
+#endif
+
 namespace rx
 {
 // Intel
@@ -284,4 +288,15 @@ bool IsWayland()
     return isWayland;
 }
 
+bool IsWin10OrGreater()
+{
+#if defined(ANGLE_ENABLE_WINDOWS_UWP)
+    return true;
+#elif defined(ANGLE_PLATFORM_WINDOWS)
+    return IsWindows10OrGreater();
+#else
+    return false;
+#endif
+}
+
 }  // namespace rx

src/libANGLE/renderer/driver_utils.h

@@ -186,6 +186,7 @@ inline bool IsIOS()
 }
 
 bool IsWayland();
+bool IsWin10OrGreater();
 
 struct OSVersion
 {