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-exception |
6 | // |
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 | |
18 | namespace llvm { |
19 | namespace dxil { |
20 | |
21 | // Implement cbuffer layout in |
22 | // https://learn.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-packing-rules |
23 | class 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(x: (Offset - Ch) / RowAlign, y&: Ch); |
33 | } |
34 | }; |
35 | |
36 | public: |
37 | LegacyCBufferLayout(const DataLayout &DL) : DL(DL) {} |
38 | TypeSize getTypeAllocSizeInBytes(Type *Ty); |
39 | |
40 | private: |
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(Size: Offset, Align: RowAlign); |
50 | } |
51 | }; |
52 | |
53 | TypeSize LegacyCBufferLayout::getTypeAllocSizeInBytes(Type *Ty) { |
54 | return getTypeAllocSize(Ty); |
55 | } |
56 | |
57 | TypeSize LegacyCBufferLayout::applyRowAlign(TypeSize Offset, Type *EltTy) { |
58 | TypeSize AlignedOffset = alignTo4Dwords(Offset); |
59 | |
60 | if (AlignedOffset == Offset) |
61 | return Offset; |
62 | |
63 | if (isa<StructType>(Val: EltTy) || isa<ArrayType>(Val: EltTy)) |
64 | return AlignedOffset; |
65 | TypeSize Size = DL.getTypeStoreSize(Ty: EltTy); |
66 | if ((Offset + Size) > AlignedOffset) |
67 | return AlignedOffset; |
68 | else |
69 | return Offset; |
70 | } |
71 | |
72 | TypeSize LegacyCBufferLayout::getTypeAllocSize(Type *Ty) { |
73 | if (auto *ST = dyn_cast<StructType>(Val: Ty)) { |
74 | LegacyStructLayout &Layout = getStructLayout(ST); |
75 | return Layout.Size; |
76 | } else if (auto *AT = dyn_cast<ArrayType>(Val: Ty)) { |
77 | unsigned NumElts = AT->getNumElements(); |
78 | if (NumElts == 0) |
79 | return TypeSize::getFixed(ExactSize: 0); |
80 | |
81 | TypeSize EltSize = getTypeAllocSize(Ty: AT->getElementType()); |
82 | TypeSize AlignedEltSize = alignTo4Dwords(Offset: EltSize); |
83 | // Each new element start 4 dwords aligned. |
84 | return TypeSize::getFixed(ExactSize: AlignedEltSize * (NumElts - 1) + EltSize); |
85 | } else { |
86 | // NOTE: Use type store size, not align to ABI on basic types for legacy |
87 | // layout. |
88 | return DL.getTypeStoreSize(Ty); |
89 | } |
90 | } |
91 | |
92 | LegacyCBufferLayout::LegacyStructLayout & |
93 | LegacyCBufferLayout::getStructLayout(StructType *ST) { |
94 | auto it = StructLayouts.find(Val: ST); |
95 | if (it != StructLayouts.end()) |
96 | return it->second; |
97 | |
98 | TypeSize Offset = TypeSize::getFixed(ExactSize: 0); |
99 | LegacyStructLayout Layout; |
100 | Layout.ST = ST; |
101 | for (Type *EltTy : ST->elements()) { |
102 | TypeSize EltSize = getTypeAllocSize(Ty: EltTy); |
103 | if (TypeSize ScalarSize = EltTy->getScalarType()->getPrimitiveSizeInBits()) |
104 | Offset = alignTo(Size: Offset, Align: ScalarSize >> 3); |
105 | Offset = applyRowAlign(Offset, EltTy); |
106 | Layout.Offsets.emplace_back(Args&: Offset); |
107 | Offset = Offset.getWithIncrement(RHS: EltSize); |
108 | } |
109 | Layout.Size = Offset; |
110 | StructLayouts[ST] = Layout; |
111 | return StructLayouts[ST]; |
112 | } |
113 | |
114 | CBufferDataLayout::CBufferDataLayout(const DataLayout &DL, const bool IsLegacy) |
115 | : DL(DL), IsLegacyLayout(IsLegacy), |
116 | LegacyDL(IsLegacy ? std::make_unique<LegacyCBufferLayout>(args: DL) : nullptr) { |
117 | } |
118 | |
119 | CBufferDataLayout::~CBufferDataLayout() = default; |
120 | |
121 | llvm::TypeSize CBufferDataLayout::getTypeAllocSizeInBytes(Type *Ty) { |
122 | if (IsLegacyLayout) |
123 | return LegacyDL->getTypeAllocSizeInBytes(Ty); |
124 | else |
125 | return DL.getTypeAllocSize(Ty); |
126 | } |
127 | |
128 | } // namespace dxil |
129 | } // namespace llvm |
130 | |