130 lines · cpp
1//===- Target/DirectX/CBufferDataLayout.cpp - Cbuffer layout helper -------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// Utils to help cbuffer layout.10//11//===----------------------------------------------------------------------===//12 13#include "CBufferDataLayout.h"14 15#include "llvm/IR/DerivedTypes.h"16#include "llvm/IR/IRBuilder.h"17 18namespace llvm {19namespace dxil {20 21// Implement cbuffer layout in22// https://learn.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-packing-rules23class LegacyCBufferLayout {24 struct LegacyStructLayout {25 StructType *ST;26 SmallVector<uint32_t> Offsets;27 TypeSize Size = {0, false};28 std::pair<uint32_t, uint32_t> getElementLegacyOffset(unsigned Idx) const {29 assert(Idx < Offsets.size() && "Invalid element idx!");30 uint32_t Offset = Offsets[Idx];31 uint32_t Ch = Offset & (RowAlign - 1);32 return std::make_pair((Offset - Ch) / RowAlign, Ch);33 }34 };35 36public:37 LegacyCBufferLayout(const DataLayout &DL) : DL(DL) {}38 TypeSize getTypeAllocSizeInBytes(Type *Ty);39 40private:41 TypeSize applyRowAlign(TypeSize Offset, Type *EltTy);42 TypeSize getTypeAllocSize(Type *Ty);43 LegacyStructLayout &getStructLayout(StructType *ST);44 const DataLayout &DL;45 SmallDenseMap<StructType *, LegacyStructLayout> StructLayouts;46 // 4 Dwords align.47 static const uint32_t RowAlign = 16;48 static TypeSize alignTo4Dwords(TypeSize Offset) {49 return alignTo(Offset, RowAlign);50 }51};52 53TypeSize LegacyCBufferLayout::getTypeAllocSizeInBytes(Type *Ty) {54 return getTypeAllocSize(Ty);55}56 57TypeSize LegacyCBufferLayout::applyRowAlign(TypeSize Offset, Type *EltTy) {58 TypeSize AlignedOffset = alignTo4Dwords(Offset);59 60 if (AlignedOffset == Offset)61 return Offset;62 63 if (isa<StructType>(EltTy) || isa<ArrayType>(EltTy))64 return AlignedOffset;65 TypeSize Size = DL.getTypeStoreSize(EltTy);66 if ((Offset + Size) > AlignedOffset)67 return AlignedOffset;68 else69 return Offset;70}71 72TypeSize LegacyCBufferLayout::getTypeAllocSize(Type *Ty) {73 if (auto *ST = dyn_cast<StructType>(Ty)) {74 LegacyStructLayout &Layout = getStructLayout(ST);75 return Layout.Size;76 } else if (auto *AT = dyn_cast<ArrayType>(Ty)) {77 unsigned NumElts = AT->getNumElements();78 if (NumElts == 0)79 return TypeSize::getFixed(0);80 81 TypeSize EltSize = getTypeAllocSize(AT->getElementType());82 TypeSize AlignedEltSize = alignTo4Dwords(EltSize);83 // Each new element start 4 dwords aligned.84 return TypeSize::getFixed(AlignedEltSize * (NumElts - 1) + EltSize);85 } else {86 // NOTE: Use type store size, not align to ABI on basic types for legacy87 // layout.88 return DL.getTypeStoreSize(Ty);89 }90}91 92LegacyCBufferLayout::LegacyStructLayout &93LegacyCBufferLayout::getStructLayout(StructType *ST) {94 auto it = StructLayouts.find(ST);95 if (it != StructLayouts.end())96 return it->second;97 98 TypeSize Offset = TypeSize::getFixed(0);99 LegacyStructLayout Layout;100 Layout.ST = ST;101 for (Type *EltTy : ST->elements()) {102 TypeSize EltSize = getTypeAllocSize(EltTy);103 if (TypeSize ScalarSize = EltTy->getScalarType()->getPrimitiveSizeInBits())104 Offset = alignTo(Offset, ScalarSize >> 3);105 Offset = applyRowAlign(Offset, EltTy);106 Layout.Offsets.emplace_back(Offset);107 Offset = Offset.getWithIncrement(EltSize);108 }109 Layout.Size = Offset;110 StructLayouts[ST] = Layout;111 return StructLayouts[ST];112}113 114CBufferDataLayout::CBufferDataLayout(const DataLayout &DL, const bool IsLegacy)115 : DL(DL), IsLegacyLayout(IsLegacy),116 LegacyDL(IsLegacy ? std::make_unique<LegacyCBufferLayout>(DL) : nullptr) {117}118 119CBufferDataLayout::~CBufferDataLayout() = default;120 121llvm::TypeSize CBufferDataLayout::getTypeAllocSizeInBytes(Type *Ty) {122 if (IsLegacyLayout)123 return LegacyDL->getTypeAllocSizeInBytes(Ty);124 else125 return DL.getTypeAllocSize(Ty);126}127 128} // namespace dxil129} // namespace llvm130