1 //===--------- X86InterleavedAccess.cpp ----------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===--------------------------------------------------------------------===//
11 /// This file contains the X86 implementation of the interleaved accesses
12 /// optimization generating X86-specific instructions/intrinsics for
13 /// interleaved access groups.
15 //===--------------------------------------------------------------------===//
17 #include "X86ISelLowering.h"
18 #include "X86TargetMachine.h"
22 /// \brief This class holds necessary information to represent an interleaved
23 /// access group and supports utilities to lower the group into
24 /// X86-specific instructions/intrinsics.
25 /// E.g. A group of interleaving access loads (Factor = 2; accessing every
27 /// %wide.vec = load <8 x i32>, <8 x i32>* %ptr
28 /// %v0 = shuffle <8 x i32> %wide.vec, <8 x i32> undef, <0, 2, 4, 6>
29 /// %v1 = shuffle <8 x i32> %wide.vec, <8 x i32> undef, <1, 3, 5, 7>
31 class X86InterleavedAccessGroup {
32 /// \brief Reference to the wide-load instruction of an interleaved access
34 Instruction *const Inst;
36 /// \brief Reference to the shuffle(s), consumer(s) of the (load) 'Inst'.
37 ArrayRef<ShuffleVectorInst *> Shuffles;
39 /// \brief Reference to the starting index of each user-shuffle.
40 ArrayRef<unsigned> Indices;
42 /// \brief Reference to the interleaving stride in terms of elements.
43 const unsigned Factor;
45 /// \brief Reference to the underlying target.
46 const X86Subtarget &Subtarget;
52 /// \brief Breaks down a vector \p 'Inst' of N elements into \p NumSubVectors
53 /// sub vectors of type \p T. Returns true and the sub-vectors in
54 /// \p DecomposedVectors if it decomposes the Inst, returns false otherwise.
55 bool decompose(Instruction *Inst, unsigned NumSubVectors, VectorType *T,
56 SmallVectorImpl<Instruction *> &DecomposedVectors);
58 /// \brief Performs matrix transposition on a 4x4 matrix \p InputVectors and
59 /// returns the transposed-vectors in \p TransposedVectors.
62 /// In-V0 = p1, p2, p3, p4
63 /// In-V1 = q1, q2, q3, q4
64 /// In-V2 = r1, r2, r3, r4
65 /// In-V3 = s1, s2, s3, s4
67 /// Out-V0 = p1, q1, r1, s1
68 /// Out-V1 = p2, q2, r2, s2
69 /// Out-V2 = p3, q3, r3, s3
70 /// Out-V3 = P4, q4, r4, s4
71 void transpose_4x4(ArrayRef<Instruction *> InputVectors,
72 SmallVectorImpl<Value *> &TrasposedVectors);
75 /// In order to form an interleaved access group X86InterleavedAccessGroup
76 /// requires a wide-load instruction \p 'I', a group of interleaved-vectors
77 /// \p Shuffs, reference to the first indices of each interleaved-vector
78 /// \p 'Ind' and the interleaving stride factor \p F. In order to generate
79 /// X86-specific instructions/intrinsics it also requires the underlying
80 /// target information \p STarget.
81 explicit X86InterleavedAccessGroup(Instruction *I,
82 ArrayRef<ShuffleVectorInst *> Shuffs,
83 ArrayRef<unsigned> Ind,
85 const X86Subtarget &STarget,
87 : Inst(I), Shuffles(Shuffs), Indices(Ind), Factor(F), Subtarget(STarget),
88 DL(Inst->getModule()->getDataLayout()), Builder(B) {}
90 /// \brief Returns true if this interleaved access group can be lowered into
91 /// x86-specific instructions/intrinsics, false otherwise.
92 bool isSupported() const;
94 /// \brief Lowers this interleaved access group into X86-specific
95 /// instructions/intrinsics.
96 bool lowerIntoOptimizedSequence();
99 bool X86InterleavedAccessGroup::isSupported() const {
100 VectorType *ShuffleVecTy = Shuffles[0]->getType();
101 uint64_t ShuffleVecSize = DL.getTypeSizeInBits(ShuffleVecTy);
102 Type *ShuffleEltTy = ShuffleVecTy->getVectorElementType();
104 if (DL.getTypeSizeInBits(Inst->getType()) < Factor * ShuffleVecSize)
107 // Currently, lowering is supported for 64 bits on AVX.
108 if (!Subtarget.hasAVX() || ShuffleVecSize != 256 ||
109 DL.getTypeSizeInBits(ShuffleEltTy) != 64 || Factor != 4)
115 bool X86InterleavedAccessGroup::decompose(
116 Instruction *VecInst, unsigned NumSubVectors, VectorType *SubVecTy,
117 SmallVectorImpl<Instruction *> &DecomposedVectors) {
118 Type *VecTy = VecInst->getType();
120 assert(VecTy->isVectorTy() &&
121 DL.getTypeSizeInBits(VecTy) >=
122 DL.getTypeSizeInBits(SubVecTy) * NumSubVectors &&
123 "Invalid Inst-size!!!");
124 assert(VecTy->getVectorElementType() == SubVecTy->getVectorElementType() &&
125 "Element type mismatched!!!");
127 if (!isa<LoadInst>(VecInst))
130 LoadInst *LI = cast<LoadInst>(VecInst);
131 Type *VecBasePtrTy = SubVecTy->getPointerTo(LI->getPointerAddressSpace());
134 Builder.CreateBitCast(LI->getPointerOperand(), VecBasePtrTy);
136 // Generate N loads of T type
137 for (unsigned i = 0; i < NumSubVectors; i++) {
138 // TODO: Support inbounds GEP
139 Value *NewBasePtr = Builder.CreateGEP(VecBasePtr, Builder.getInt32(i));
140 Instruction *NewLoad =
141 Builder.CreateAlignedLoad(NewBasePtr, LI->getAlignment());
142 DecomposedVectors.push_back(NewLoad);
148 void X86InterleavedAccessGroup::transpose_4x4(
149 ArrayRef<Instruction *> Matrix,
150 SmallVectorImpl<Value *> &TransposedMatrix) {
151 assert(Matrix.size() == 4 && "Invalid matrix size");
152 TransposedMatrix.resize(4);
154 // dst = src1[0,1],src2[0,1]
155 uint32_t IntMask1[] = {0, 1, 4, 5};
156 ArrayRef<uint32_t> Mask = makeArrayRef(IntMask1, 4);
157 Value *IntrVec1 = Builder.CreateShuffleVector(Matrix[0], Matrix[2], Mask);
158 Value *IntrVec2 = Builder.CreateShuffleVector(Matrix[1], Matrix[3], Mask);
160 // dst = src1[2,3],src2[2,3]
161 uint32_t IntMask2[] = {2, 3, 6, 7};
162 Mask = makeArrayRef(IntMask2, 4);
163 Value *IntrVec3 = Builder.CreateShuffleVector(Matrix[0], Matrix[2], Mask);
164 Value *IntrVec4 = Builder.CreateShuffleVector(Matrix[1], Matrix[3], Mask);
166 // dst = src1[0],src2[0],src1[2],src2[2]
167 uint32_t IntMask3[] = {0, 4, 2, 6};
168 Mask = makeArrayRef(IntMask3, 4);
169 TransposedMatrix[0] = Builder.CreateShuffleVector(IntrVec1, IntrVec2, Mask);
170 TransposedMatrix[2] = Builder.CreateShuffleVector(IntrVec3, IntrVec4, Mask);
172 // dst = src1[1],src2[1],src1[3],src2[3]
173 uint32_t IntMask4[] = {1, 5, 3, 7};
174 Mask = makeArrayRef(IntMask4, 4);
175 TransposedMatrix[1] = Builder.CreateShuffleVector(IntrVec1, IntrVec2, Mask);
176 TransposedMatrix[3] = Builder.CreateShuffleVector(IntrVec3, IntrVec4, Mask);
179 // Lowers this interleaved access group into X86-specific
180 // instructions/intrinsics.
181 bool X86InterleavedAccessGroup::lowerIntoOptimizedSequence() {
182 SmallVector<Instruction *, 4> DecomposedVectors;
183 VectorType *VecTy = Shuffles[0]->getType();
184 // Try to generate target-sized register(/instruction).
185 if (!decompose(Inst, Factor, VecTy, DecomposedVectors))
188 SmallVector<Value *, 4> TransposedVectors;
189 // Perform matrix-transposition in order to compute interleaved
190 // results by generating some sort of (optimized) target-specific
192 transpose_4x4(DecomposedVectors, TransposedVectors);
194 // Now replace the unoptimized-interleaved-vectors with the
195 // transposed-interleaved vectors.
196 for (unsigned i = 0; i < Shuffles.size(); i++)
197 Shuffles[i]->replaceAllUsesWith(TransposedVectors[Indices[i]]);
202 // Lower interleaved load(s) into target specific instructions/
203 // intrinsics. Lowering sequence varies depending on the vector-types, factor,
204 // number of shuffles and ISA.
205 // Currently, lowering is supported for 4x64 bits with Factor = 4 on AVX.
206 bool X86TargetLowering::lowerInterleavedLoad(
207 LoadInst *LI, ArrayRef<ShuffleVectorInst *> Shuffles,
208 ArrayRef<unsigned> Indices, unsigned Factor) const {
209 assert(Factor >= 2 && Factor <= getMaxSupportedInterleaveFactor() &&
210 "Invalid interleave factor");
211 assert(!Shuffles.empty() && "Empty shufflevector input");
212 assert(Shuffles.size() == Indices.size() &&
213 "Unmatched number of shufflevectors and indices");
215 // Create an interleaved access group.
216 IRBuilder<> Builder(LI);
217 X86InterleavedAccessGroup Grp(LI, Shuffles, Indices, Factor, Subtarget,
220 return Grp.isSupported() && Grp.lowerIntoOptimizedSequence();