1 ///===- LazyMachineBlockFrequencyInfo.h - Lazy Block Frequency -*- 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 /// \file 9 /// This is an alternative analysis pass to MachineBlockFrequencyInfo. The 10 /// difference is that with this pass the block frequencies are not computed 11 /// when the analysis pass is executed but rather when the BFI result is 12 /// explicitly requested by the analysis client. 13 /// 14 ///===---------------------------------------------------------------------===// 15 16 #ifndef LLVM_ANALYSIS_LAZYMACHINEBLOCKFREQUENCYINFO_H 17 #define LLVM_ANALYSIS_LAZYMACHINEBLOCKFREQUENCYINFO_H 18 19 #include "llvm/CodeGen/MachineBlockFrequencyInfo.h" 20 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h" 21 #include "llvm/CodeGen/MachineDominators.h" 22 #include "llvm/CodeGen/MachineLoopInfo.h" 23 24 namespace llvm { 25 /// This is an alternative analysis pass to MachineBlockFrequencyInfo. 26 /// The difference is that with this pass, the block frequencies are not 27 /// computed when the analysis pass is executed but rather when the BFI result 28 /// is explicitly requested by the analysis client. 29 /// 30 /// This works by checking querying if MBFI is available and otherwise 31 /// generating MBFI on the fly. In this case the passes required for (LI, DT) 32 /// are also queried before being computed on the fly. 33 /// 34 /// Note that it is expected that we wouldn't need this functionality for the 35 /// new PM since with the new PM, analyses are executed on demand. 36 37 class LazyMachineBlockFrequencyInfoPass : public MachineFunctionPass { 38 private: 39 /// If generated on the fly this own the instance. 40 mutable std::unique_ptr<MachineBlockFrequencyInfo> OwnedMBFI; 41 42 /// If generated on the fly this own the instance. 43 mutable std::unique_ptr<MachineLoopInfo> OwnedMLI; 44 45 /// If generated on the fly this own the instance. 46 mutable std::unique_ptr<MachineDominatorTree> OwnedMDT; 47 48 /// The function. 49 MachineFunction *MF = nullptr; 50 51 /// Calculate MBFI and all other analyses that's not available and 52 /// required by BFI. 53 MachineBlockFrequencyInfo &calculateIfNotAvailable() const; 54 55 public: 56 static char ID; 57 58 LazyMachineBlockFrequencyInfoPass(); 59 60 /// Compute and return the block frequencies. getBFI()61 MachineBlockFrequencyInfo &getBFI() { return calculateIfNotAvailable(); } 62 63 /// Compute and return the block frequencies. getBFI()64 const MachineBlockFrequencyInfo &getBFI() const { 65 return calculateIfNotAvailable(); 66 } 67 68 void getAnalysisUsage(AnalysisUsage &AU) const override; 69 70 bool runOnMachineFunction(MachineFunction &F) override; 71 void releaseMemory() override; 72 void print(raw_ostream &OS, const Module *M) const override; 73 }; 74 } 75 #endif 76