1 //===- LoopVectorize.h ------------------------------------------*- C++ -*-===// 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 // This is the LLVM loop vectorizer. This pass modifies 'vectorizable' loops 10 // and generates target-independent LLVM-IR. 11 // The vectorizer uses the TargetTransformInfo analysis to estimate the costs 12 // of instructions in order to estimate the profitability of vectorization. 13 // 14 // The loop vectorizer combines consecutive loop iterations into a single 15 // 'wide' iteration. After this transformation the index is incremented 16 // by the SIMD vector width, and not by one. 17 // 18 // This pass has three parts: 19 // 1. The main loop pass that drives the different parts. 20 // 2. LoopVectorizationLegality - A unit that checks for the legality 21 // of the vectorization. 22 // 3. InnerLoopVectorizer - A unit that performs the actual 23 // widening of instructions. 24 // 4. LoopVectorizationCostModel - A unit that checks for the profitability 25 // of vectorization. It decides on the optimal vector width, which 26 // can be one, if vectorization is not profitable. 27 // 28 // There is a development effort going on to migrate loop vectorizer to the 29 // VPlan infrastructure and to introduce outer loop vectorization support (see 30 // docs/Proposal/VectorizationPlan.rst and 31 // http://lists.llvm.org/pipermail/llvm-dev/2017-December/119523.html). For this 32 // purpose, we temporarily introduced the VPlan-native vectorization path: an 33 // alternative vectorization path that is natively implemented on top of the 34 // VPlan infrastructure. See EnableVPlanNativePath for enabling. 35 // 36 //===----------------------------------------------------------------------===// 37 // 38 // The reduction-variable vectorization is based on the paper: 39 // D. Nuzman and R. Henderson. Multi-platform Auto-vectorization. 40 // 41 // Variable uniformity checks are inspired by: 42 // Karrenberg, R. and Hack, S. Whole Function Vectorization. 43 // 44 // The interleaved access vectorization is based on the paper: 45 // Dorit Nuzman, Ira Rosen and Ayal Zaks. Auto-Vectorization of Interleaved 46 // Data for SIMD 47 // 48 // Other ideas/concepts are from: 49 // A. Zaks and D. Nuzman. Autovectorization in GCC-two years later. 50 // 51 // S. Maleki, Y. Gao, M. Garzaran, T. Wong and D. Padua. An Evaluation of 52 // Vectorizing Compilers. 53 // 54 //===----------------------------------------------------------------------===// 55 56 #ifndef LLVM_TRANSFORMS_VECTORIZE_LOOPVECTORIZE_H 57 #define LLVM_TRANSFORMS_VECTORIZE_LOOPVECTORIZE_H 58 59 #include "llvm/IR/PassManager.h" 60 #include "llvm/Support/CommandLine.h" 61 #include <functional> 62 63 namespace llvm { 64 65 class AAResults; 66 class AssumptionCache; 67 class BlockFrequencyInfo; 68 class DemandedBits; 69 class DominatorTree; 70 class Function; 71 class Loop; 72 class LoopAccessInfo; 73 class LoopInfo; 74 class OptimizationRemarkEmitter; 75 class ProfileSummaryInfo; 76 class ScalarEvolution; 77 class TargetLibraryInfo; 78 class TargetTransformInfo; 79 80 extern cl::opt<bool> EnableLoopInterleaving; 81 extern cl::opt<bool> EnableLoopVectorization; 82 83 struct LoopVectorizeOptions { 84 /// If false, consider all loops for interleaving. 85 /// If true, only loops that explicitly request interleaving are considered. 86 bool InterleaveOnlyWhenForced; 87 88 /// If false, consider all loops for vectorization. 89 /// If true, only loops that explicitly request vectorization are considered. 90 bool VectorizeOnlyWhenForced; 91 92 /// The current defaults when creating the pass with no arguments are: 93 /// EnableLoopInterleaving = true and EnableLoopVectorization = true. This 94 /// means that interleaving default is consistent with the cl::opt flag, while 95 /// vectorization is not. 96 /// FIXME: The default for EnableLoopVectorization in the cl::opt should be 97 /// set to true, and the corresponding change to account for this be made in 98 /// opt.cpp. The initializations below will become: 99 /// InterleaveOnlyWhenForced(!EnableLoopInterleaving) 100 /// VectorizeOnlyWhenForced(!EnableLoopVectorization). 101 LoopVectorizeOptions() 102 : InterleaveOnlyWhenForced(false), VectorizeOnlyWhenForced(false) {} 103 LoopVectorizeOptions(bool InterleaveOnlyWhenForced, 104 bool VectorizeOnlyWhenForced) 105 : InterleaveOnlyWhenForced(InterleaveOnlyWhenForced), 106 VectorizeOnlyWhenForced(VectorizeOnlyWhenForced) {} 107 108 LoopVectorizeOptions &setInterleaveOnlyWhenForced(bool Value) { 109 InterleaveOnlyWhenForced = Value; 110 return *this; 111 } 112 113 LoopVectorizeOptions &setVectorizeOnlyWhenForced(bool Value) { 114 VectorizeOnlyWhenForced = Value; 115 return *this; 116 } 117 }; 118 119 /// Storage for information about made changes. 120 struct LoopVectorizeResult { 121 bool MadeAnyChange; 122 bool MadeCFGChange; 123 124 LoopVectorizeResult(bool MadeAnyChange, bool MadeCFGChange) 125 : MadeAnyChange(MadeAnyChange), MadeCFGChange(MadeCFGChange) {} 126 }; 127 128 /// The LoopVectorize Pass. 129 struct LoopVectorizePass : public PassInfoMixin<LoopVectorizePass> { 130 private: 131 /// If false, consider all loops for interleaving. 132 /// If true, only loops that explicitly request interleaving are considered. 133 bool InterleaveOnlyWhenForced; 134 135 /// If false, consider all loops for vectorization. 136 /// If true, only loops that explicitly request vectorization are considered. 137 bool VectorizeOnlyWhenForced; 138 139 public: 140 LoopVectorizePass(LoopVectorizeOptions Opts = {}); 141 142 ScalarEvolution *SE; 143 LoopInfo *LI; 144 TargetTransformInfo *TTI; 145 DominatorTree *DT; 146 BlockFrequencyInfo *BFI; 147 TargetLibraryInfo *TLI; 148 DemandedBits *DB; 149 AAResults *AA; 150 AssumptionCache *AC; 151 std::function<const LoopAccessInfo &(Loop &)> *GetLAA; 152 OptimizationRemarkEmitter *ORE; 153 ProfileSummaryInfo *PSI; 154 155 PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); 156 157 // Shim for old PM. 158 LoopVectorizeResult 159 runImpl(Function &F, ScalarEvolution &SE_, LoopInfo &LI_, 160 TargetTransformInfo &TTI_, DominatorTree &DT_, 161 BlockFrequencyInfo &BFI_, TargetLibraryInfo *TLI_, DemandedBits &DB_, 162 AAResults &AA_, AssumptionCache &AC_, 163 std::function<const LoopAccessInfo &(Loop &)> &GetLAA_, 164 OptimizationRemarkEmitter &ORE_, ProfileSummaryInfo *PSI_); 165 166 bool processLoop(Loop *L); 167 }; 168 169 /// Reports a vectorization failure: print \p DebugMsg for debugging 170 /// purposes along with the corresponding optimization remark \p RemarkName. 171 /// If \p I is passed, it is an instruction that prevents vectorization. 172 /// Otherwise, the loop \p TheLoop is used for the location of the remark. 173 void reportVectorizationFailure(const StringRef DebugMsg, 174 const StringRef OREMsg, const StringRef ORETag, 175 OptimizationRemarkEmitter *ORE, Loop *TheLoop, Instruction *I = nullptr); 176 177 /// Reports an informative message: print \p Msg for debugging purposes as well 178 /// as an optimization remark. Uses either \p I as location of the remark, or 179 /// otherwise \p TheLoop. 180 void reportVectorizationInfo(const StringRef OREMsg, const StringRef ORETag, 181 OptimizationRemarkEmitter *ORE, Loop *TheLoop, 182 Instruction *I = nullptr); 183 184 } // end namespace llvm 185 186 #endif // LLVM_TRANSFORMS_VECTORIZE_LOOPVECTORIZE_H 187
Indexes created Mon Jun 15 00:25:07 UTC 2026