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///===- LazyMachineBlockFrequencyInfo.h - Lazy Block Frequency -*- C++ -*--===//
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///
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/// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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/// See https://llvm.org/LICENSE.txt for license information.
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/// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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///
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///===---------------------------------------------------------------------===//
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/// \file
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/// This is an alternative analysis pass to MachineBlockFrequencyInfo.  The
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/// difference is that with this pass the block frequencies are not computed
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/// when the analysis pass is executed but rather when the BFI result is
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/// explicitly requested by the analysis client.
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///
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///===---------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_LAZYMACHINEBLOCKFREQUENCYINFO_H
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#define LLVM_CODEGEN_LAZYMACHINEBLOCKFREQUENCYINFO_H
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#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
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#include "llvm/CodeGen/MachineDominators.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineLoopInfo.h"
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namespace llvm {
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/// This is an alternative analysis pass to MachineBlockFrequencyInfo.
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/// The difference is that with this pass, the block frequencies are not
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/// computed when the analysis pass is executed but rather when the BFI result
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/// is explicitly requested by the analysis client.
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///
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/// This works by checking querying if MBFI is available and otherwise
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/// generating MBFI on the fly.  In this case the passes required for (LI, DT)
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/// are also queried before being computed on the fly.
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///
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/// Note that it is expected that we wouldn't need this functionality for the
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/// new PM since with the new PM, analyses are executed on demand.
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class LazyMachineBlockFrequencyInfoPass : public MachineFunctionPass {
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private:
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  /// If generated on the fly this own the instance.
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  mutable std::unique_ptr<MachineBlockFrequencyInfo> OwnedMBFI;
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  /// If generated on the fly this own the instance.
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  mutable std::unique_ptr<MachineLoopInfo> OwnedMLI;
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  /// If generated on the fly this own the instance.
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  mutable std::unique_ptr<MachineDominatorTree> OwnedMDT;
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  /// The function.
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  MachineFunction *MF = nullptr;
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  /// Calculate MBFI and all other analyses that's not available and
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  /// required by BFI.
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  MachineBlockFrequencyInfo &calculateIfNotAvailable() const;
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public:
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  static char ID;
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  LazyMachineBlockFrequencyInfoPass();
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  /// Compute and return the block frequencies.
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  MachineBlockFrequencyInfo &getBFI() { return calculateIfNotAvailable(); }
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  /// Compute and return the block frequencies.
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  const MachineBlockFrequencyInfo &getBFI() const {
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    return calculateIfNotAvailable();
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  }
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  void getAnalysisUsage(AnalysisUsage &AU) const override;
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  bool runOnMachineFunction(MachineFunction &F) override;
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  void releaseMemory() override;
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  void print(raw_ostream &OS, const Module *M) const override;
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};
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}
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#endif