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/Compiler.h" 20 #include "llvm/Support/Printable.h" 21 #include <cstdint> 22 #include <memory> 23 #include <optional> 24 25 namespace llvm { 26 27 class BasicBlock; 28 class BranchProbabilityInfo; 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 LLVM_ABI BlockFrequencyInfo(); 45 LLVM_ABI BlockFrequencyInfo(const Function &F, 46 const BranchProbabilityInfo &BPI, 47 const LoopInfo &LI); 48 BlockFrequencyInfo(const BlockFrequencyInfo &) = delete; 49 BlockFrequencyInfo &operator=(const BlockFrequencyInfo &) = delete; 50 LLVM_ABI BlockFrequencyInfo(BlockFrequencyInfo &&Arg); 51 LLVM_ABI BlockFrequencyInfo &operator=(BlockFrequencyInfo &&RHS); 52 LLVM_ABI ~BlockFrequencyInfo(); 53 54 /// Handle invalidation explicitly. 55 LLVM_ABI bool invalidate(Function &F, const PreservedAnalyses &PA, 56 FunctionAnalysisManager::Invalidator &); 57 58 LLVM_ABI const Function *getFunction() const; 59 LLVM_ABI const BranchProbabilityInfo *getBPI() const; 60 LLVM_ABI void view(StringRef = "BlockFrequencyDAGs") const; 61 62 /// getblockFreq - Return block frequency. Return 0 if we don't have the 63 /// information. Please note that initial frequency is equal to ENTRY_FREQ. It 64 /// means that we should not rely on the value itself, but only on the 65 /// comparison to the other block frequencies. We do this to avoid using of 66 /// floating points. 67 LLVM_ABI BlockFrequency getBlockFreq(const BasicBlock *BB) const; 68 69 /// Returns the estimated profile count of \p BB. 70 /// This computes the relative block frequency of \p BB and multiplies it by 71 /// the enclosing function's count (if available) and returns the value. 72 LLVM_ABI std::optional<uint64_t> 73 getBlockProfileCount(const BasicBlock *BB, bool AllowSynthetic = false) const; 74 75 /// Returns the estimated profile count of \p Freq. 76 /// This uses the frequency \p Freq and multiplies it by 77 /// the enclosing function's count (if available) and returns the value. 78 LLVM_ABI std::optional<uint64_t> 79 getProfileCountFromFreq(BlockFrequency Freq) const; 80 81 /// Returns true if \p BB is an irreducible loop header 82 /// block. Otherwise false. 83 LLVM_ABI bool isIrrLoopHeader(const BasicBlock *BB); 84 85 // Set the frequency of the given basic block. 86 LLVM_ABI void setBlockFreq(const BasicBlock *BB, BlockFrequency Freq); 87 88 /// Set the frequency of \p ReferenceBB to \p Freq and scale the frequencies 89 /// of the blocks in \p BlocksToScale such that their frequencies relative 90 /// to \p ReferenceBB remain unchanged. 91 LLVM_ABI void 92 setBlockFreqAndScale(const BasicBlock *ReferenceBB, BlockFrequency Freq, 93 SmallPtrSetImpl<BasicBlock *> &BlocksToScale); 94 95 /// calculate - compute block frequency info for the given function. 96 LLVM_ABI void calculate(const Function &F, const BranchProbabilityInfo &BPI, 97 const LoopInfo &LI); 98 99 LLVM_ABI BlockFrequency getEntryFreq() const; 100 LLVM_ABI void releaseMemory(); 101 LLVM_ABI void print(raw_ostream &OS) const; 102 103 // Compare to the other BFI and verify they match. 104 LLVM_ABI void verifyMatch(BlockFrequencyInfo &Other) const; 105 }; 106 107 /// Print the block frequency @p Freq relative to the current functions entry 108 /// frequency. Returns a Printable object that can be piped via `<<` to a 109 /// `raw_ostream`. 110 LLVM_ABI Printable printBlockFreq(const BlockFrequencyInfo &BFI, 111 BlockFrequency Freq); 112 113 /// Convenience function equivalent to calling 114 /// `printBlockFreq(BFI, BFI.getBlocakFreq(&BB))`. 115 LLVM_ABI Printable printBlockFreq(const BlockFrequencyInfo &BFI, 116 const BasicBlock &BB); 117 118 /// Analysis pass which computes \c BlockFrequencyInfo. 119 class BlockFrequencyAnalysis 120 : public AnalysisInfoMixin<BlockFrequencyAnalysis> { 121 friend AnalysisInfoMixin<BlockFrequencyAnalysis>; 122 123 LLVM_ABI static AnalysisKey Key; 124 125 public: 126 /// Provide the result type for this analysis pass. 127 using Result = BlockFrequencyInfo; 128 129 /// Run the analysis pass over a function and produce BFI. 130 LLVM_ABI Result run(Function &F, FunctionAnalysisManager &AM); 131 }; 132 133 /// Printer pass for the \c BlockFrequencyInfo results. 134 class BlockFrequencyPrinterPass 135 : public PassInfoMixin<BlockFrequencyPrinterPass> { 136 raw_ostream &OS; 137 138 public: BlockFrequencyPrinterPass(raw_ostream & OS)139 explicit BlockFrequencyPrinterPass(raw_ostream &OS) : OS(OS) {} 140 141 LLVM_ABI PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); 142 isRequired()143 static bool isRequired() { return true; } 144 }; 145 146 /// Legacy analysis pass which computes \c BlockFrequencyInfo. 147 class LLVM_ABI BlockFrequencyInfoWrapperPass : public FunctionPass { 148 BlockFrequencyInfo BFI; 149 150 public: 151 static char ID; 152 153 BlockFrequencyInfoWrapperPass(); 154 ~BlockFrequencyInfoWrapperPass() override; 155 getBFI()156 BlockFrequencyInfo &getBFI() { return BFI; } getBFI()157 const BlockFrequencyInfo &getBFI() const { return BFI; } 158 159 void getAnalysisUsage(AnalysisUsage &AU) const override; 160 161 bool runOnFunction(Function &F) override; 162 void releaseMemory() override; 163 void print(raw_ostream &OS, const Module *M) const override; 164 }; 165 166 } // end namespace llvm 167 168 #endif // LLVM_ANALYSIS_BLOCKFREQUENCYINFO_H 169