1 //===- MachineBlockFrequencyInfo.h - MBB 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_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H 14 #define LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H 15 16 #include "llvm/CodeGen/MachineFunctionPass.h" 17 #include "llvm/CodeGen/MachinePassManager.h" 18 #include "llvm/Support/BlockFrequency.h" 19 #include "llvm/Support/Compiler.h" 20 #include <cstdint> 21 #include <memory> 22 #include <optional> 23 24 namespace llvm { 25 26 template <class BlockT> class BlockFrequencyInfoImpl; 27 class MachineBasicBlock; 28 class MachineBranchProbabilityInfo; 29 class MachineFunction; 30 class MachineLoopInfo; 31 class raw_ostream; 32 33 /// MachineBlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation 34 /// to estimate machine basic block frequencies. 35 class MachineBlockFrequencyInfo { 36 using ImplType = BlockFrequencyInfoImpl<MachineBasicBlock>; 37 std::unique_ptr<ImplType> MBFI; 38 39 public: 40 LLVM_ABI MachineBlockFrequencyInfo(); // Legacy pass manager only. 41 LLVM_ABI explicit MachineBlockFrequencyInfo( 42 MachineFunction &F, MachineBranchProbabilityInfo &MBPI, 43 MachineLoopInfo &MLI); 44 LLVM_ABI MachineBlockFrequencyInfo(MachineBlockFrequencyInfo &&); 45 LLVM_ABI ~MachineBlockFrequencyInfo(); 46 47 /// Handle invalidation explicitly. 48 LLVM_ABI bool invalidate(MachineFunction &F, const PreservedAnalyses &PA, 49 MachineFunctionAnalysisManager::Invalidator &); 50 51 /// calculate - compute block frequency info for the given function. 52 LLVM_ABI void calculate(const MachineFunction &F, 53 const MachineBranchProbabilityInfo &MBPI, 54 const MachineLoopInfo &MLI); 55 56 LLVM_ABI void print(raw_ostream &OS); 57 58 LLVM_ABI void releaseMemory(); 59 60 /// getblockFreq - Return block frequency. Return 0 if we don't have the 61 /// information. Please note that initial frequency is equal to 1024. It means 62 /// that we should not rely on the value itself, but only on the comparison to 63 /// the other block frequencies. We do this to avoid using of floating points. 64 /// For example, to get the frequency of a block relative to the entry block, 65 /// divide the integral value returned by this function (the 66 /// BlockFrequency::getFrequency() value) by getEntryFreq(). 67 LLVM_ABI BlockFrequency getBlockFreq(const MachineBasicBlock *MBB) const; 68 69 /// Compute the frequency of the block, relative to the entry block. 70 /// This API assumes getEntryFreq() is non-zero. getBlockFreqRelativeToEntryBlock(const MachineBasicBlock * MBB)71 double getBlockFreqRelativeToEntryBlock(const MachineBasicBlock *MBB) const { 72 assert(getEntryFreq() != BlockFrequency(0) && 73 "getEntryFreq() should not return 0 here!"); 74 return static_cast<double>(getBlockFreq(MBB).getFrequency()) / 75 static_cast<double>(getEntryFreq().getFrequency()); 76 } 77 78 LLVM_ABI std::optional<uint64_t> 79 getBlockProfileCount(const MachineBasicBlock *MBB) const; 80 LLVM_ABI std::optional<uint64_t> 81 getProfileCountFromFreq(BlockFrequency Freq) const; 82 83 LLVM_ABI bool isIrrLoopHeader(const MachineBasicBlock *MBB) const; 84 85 /// incrementally calculate block frequencies when we split edges, to avoid 86 /// full CFG traversal. 87 LLVM_ABI void onEdgeSplit(const MachineBasicBlock &NewPredecessor, 88 const MachineBasicBlock &NewSuccessor, 89 const MachineBranchProbabilityInfo &MBPI); 90 91 LLVM_ABI const MachineFunction *getFunction() const; 92 LLVM_ABI const MachineBranchProbabilityInfo *getMBPI() const; 93 94 /// Pop up a ghostview window with the current block frequency propagation 95 /// rendered using dot. 96 LLVM_ABI void view(const Twine &Name, bool isSimple = true) const; 97 98 /// Divide a block's BlockFrequency::getFrequency() value by this value to 99 /// obtain the entry block - relative frequency of said block. 100 LLVM_ABI BlockFrequency getEntryFreq() const; 101 }; 102 103 /// Print the block frequency @p Freq relative to the current functions entry 104 /// frequency. Returns a Printable object that can be piped via `<<` to a 105 /// `raw_ostream`. 106 LLVM_ABI Printable printBlockFreq(const MachineBlockFrequencyInfo &MBFI, 107 BlockFrequency Freq); 108 109 /// Convenience function equivalent to calling 110 /// `printBlockFreq(MBFI, MBFI.getBlockFreq(&MBB))`. 111 LLVM_ABI Printable printBlockFreq(const MachineBlockFrequencyInfo &MBFI, 112 const MachineBasicBlock &MBB); 113 114 class MachineBlockFrequencyAnalysis 115 : public AnalysisInfoMixin<MachineBlockFrequencyAnalysis> { 116 friend AnalysisInfoMixin<MachineBlockFrequencyAnalysis>; 117 LLVM_ABI static AnalysisKey Key; 118 119 public: 120 using Result = MachineBlockFrequencyInfo; 121 122 LLVM_ABI Result run(MachineFunction &MF, 123 MachineFunctionAnalysisManager &MFAM); 124 }; 125 126 /// Printer pass for the \c MachineBlockFrequencyInfo results. 127 class MachineBlockFrequencyPrinterPass 128 : public PassInfoMixin<MachineBlockFrequencyPrinterPass> { 129 raw_ostream &OS; 130 131 public: MachineBlockFrequencyPrinterPass(raw_ostream & OS)132 explicit MachineBlockFrequencyPrinterPass(raw_ostream &OS) : OS(OS) {} 133 134 LLVM_ABI PreservedAnalyses run(MachineFunction &MF, 135 MachineFunctionAnalysisManager &MFAM); 136 isRequired()137 static bool isRequired() { return true; } 138 }; 139 140 class LLVM_ABI MachineBlockFrequencyInfoWrapperPass 141 : public MachineFunctionPass { 142 MachineBlockFrequencyInfo MBFI; 143 144 public: 145 static char ID; 146 147 MachineBlockFrequencyInfoWrapperPass(); 148 149 void getAnalysisUsage(AnalysisUsage &AU) const override; 150 151 bool runOnMachineFunction(MachineFunction &F) override; 152 releaseMemory()153 void releaseMemory() override { MBFI.releaseMemory(); } 154 getMBFI()155 MachineBlockFrequencyInfo &getMBFI() { return MBFI; } 156 getMBFI()157 const MachineBlockFrequencyInfo &getMBFI() const { return MBFI; } 158 }; 159 } // end namespace llvm 160 161 #endif // LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H 162