1 //===- BlockFrequencyInfo.h - Block Frequency Analysis ----------*- 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 // Loops should be simplified before this analysis. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_ANALYSIS_BLOCKFREQUENCYINFO_H 14 #define LLVM_ANALYSIS_BLOCKFREQUENCYINFO_H 15 16 #include "llvm/IR/PassManager.h" 17 #include "llvm/Pass.h" 18 #include "llvm/Support/BlockFrequency.h" 19 #include "llvm/Support/Printable.h" 20 #include <cstdint> 21 #include <memory> 22 #include <optional> 23 24 namespace llvm { 25 26 class BasicBlock; 27 class BranchProbabilityInfo; 28 class Function; 29 class LoopInfo; 30 class Module; 31 class raw_ostream; 32 template <class BlockT> class BlockFrequencyInfoImpl; 33 34 enum PGOViewCountsType { PGOVCT_None, PGOVCT_Graph, PGOVCT_Text }; 35 36 /// BlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation to 37 /// estimate IR basic block frequencies. 38 class BlockFrequencyInfo { 39 using ImplType = BlockFrequencyInfoImpl<BasicBlock>; 40 41 std::unique_ptr<ImplType> BFI; 42 43 public: 44 BlockFrequencyInfo(); 45 BlockFrequencyInfo(const Function &F, const BranchProbabilityInfo &BPI, 46 const LoopInfo &LI); 47 BlockFrequencyInfo(const BlockFrequencyInfo &) = delete; 48 BlockFrequencyInfo &operator=(const BlockFrequencyInfo &) = delete; 49 BlockFrequencyInfo(BlockFrequencyInfo &&Arg); 50 BlockFrequencyInfo &operator=(BlockFrequencyInfo &&RHS); 51 ~BlockFrequencyInfo(); 52 53 /// Handle invalidation explicitly. 54 bool invalidate(Function &F, const PreservedAnalyses &PA, 55 FunctionAnalysisManager::Invalidator &); 56 57 const Function *getFunction() const; 58 const BranchProbabilityInfo *getBPI() const; 59 void view(StringRef = "BlockFrequencyDAGs") const; 60 61 /// getblockFreq - Return block frequency. Return 0 if we don't have the 62 /// information. Please note that initial frequency is equal to ENTRY_FREQ. It 63 /// means that we should not rely on the value itself, but only on the 64 /// comparison to the other block frequencies. We do this to avoid using of 65 /// floating points. 66 BlockFrequency getBlockFreq(const BasicBlock *BB) const; 67 68 /// Returns the estimated profile count of \p BB. 69 /// This computes the relative block frequency of \p BB and multiplies it by 70 /// the enclosing function's count (if available) and returns the value. 71 std::optional<uint64_t> 72 getBlockProfileCount(const BasicBlock *BB, bool AllowSynthetic = false) const; 73 74 /// Returns the estimated profile count of \p Freq. 75 /// This uses the frequency \p Freq and multiplies it by 76 /// the enclosing function's count (if available) and returns the value. 77 std::optional<uint64_t> getProfileCountFromFreq(BlockFrequency Freq) const; 78 79 /// Returns true if \p BB is an irreducible loop header 80 /// block. Otherwise false. 81 bool isIrrLoopHeader(const BasicBlock *BB); 82 83 // Set the frequency of the given basic block. 84 void setBlockFreq(const BasicBlock *BB, BlockFrequency Freq); 85 86 /// Set the frequency of \p ReferenceBB to \p Freq and scale the frequencies 87 /// of the blocks in \p BlocksToScale such that their frequencies relative 88 /// to \p ReferenceBB remain unchanged. 89 void setBlockFreqAndScale(const BasicBlock *ReferenceBB, BlockFrequency Freq, 90 SmallPtrSetImpl<BasicBlock *> &BlocksToScale); 91 92 /// calculate - compute block frequency info for the given function. 93 void calculate(const Function &F, const BranchProbabilityInfo &BPI, 94 const LoopInfo &LI); 95 96 BlockFrequency getEntryFreq() const; 97 void releaseMemory(); 98 void print(raw_ostream &OS) const; 99 100 // Compare to the other BFI and verify they match. 101 void verifyMatch(BlockFrequencyInfo &Other) const; 102 }; 103 104 /// Print the block frequency @p Freq relative to the current functions entry 105 /// frequency. Returns a Printable object that can be piped via `<<` to a 106 /// `raw_ostream`. 107 Printable printBlockFreq(const BlockFrequencyInfo &BFI, BlockFrequency Freq); 108 109 /// Convenience function equivalent to calling 110 /// `printBlockFreq(BFI, BFI.getBlocakFreq(&BB))`. 111 Printable printBlockFreq(const BlockFrequencyInfo &BFI, const BasicBlock &BB); 112 113 /// Analysis pass which computes \c BlockFrequencyInfo. 114 class BlockFrequencyAnalysis 115 : public AnalysisInfoMixin<BlockFrequencyAnalysis> { 116 friend AnalysisInfoMixin<BlockFrequencyAnalysis>; 117 118 static AnalysisKey Key; 119 120 public: 121 /// Provide the result type for this analysis pass. 122 using Result = BlockFrequencyInfo; 123 124 /// Run the analysis pass over a function and produce BFI. 125 Result run(Function &F, FunctionAnalysisManager &AM); 126 }; 127 128 /// Printer pass for the \c BlockFrequencyInfo results. 129 class BlockFrequencyPrinterPass 130 : public PassInfoMixin<BlockFrequencyPrinterPass> { 131 raw_ostream &OS; 132 133 public: 134 explicit BlockFrequencyPrinterPass(raw_ostream &OS) : OS(OS) {} 135 136 PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); 137 }; 138 139 /// Legacy analysis pass which computes \c BlockFrequencyInfo. 140 class BlockFrequencyInfoWrapperPass : public FunctionPass { 141 BlockFrequencyInfo BFI; 142 143 public: 144 static char ID; 145 146 BlockFrequencyInfoWrapperPass(); 147 ~BlockFrequencyInfoWrapperPass() override; 148 149 BlockFrequencyInfo &getBFI() { return BFI; } 150 const BlockFrequencyInfo &getBFI() const { return BFI; } 151 152 void getAnalysisUsage(AnalysisUsage &AU) const override; 153 154 bool runOnFunction(Function &F) override; 155 void releaseMemory() override; 156 void print(raw_ostream &OS, const Module *M) const override; 157 }; 158 159 } // end namespace llvm 160 161 #endif // LLVM_ANALYSIS_BLOCKFREQUENCYINFO_H 162