include/llvm/CodeGen/LazyMachineBlockFrequencyInfo.h

   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.
  61   MachineBlockFrequencyInfo &getBFI() { return calculateIfNotAvailable(); }
  62
  63   /// Compute and return the block frequencies.
  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