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