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Summary: Currently the block frequency analysis is an approximation for irreducible loops. The new irreducible loop metadata is used to annotate the irreducible loop headers with their header weights based on the PGO profile (currently this is approximated to be evenly weighted) and to help improve the accuracy of the block frequency analysis for irreducible loops. This patch is a basic support for this. Reviewers: davidxl Reviewed By: davidxl Subscribers: mehdi_amini, llvm-commits, eraman Differential Revision: https://reviews.llvm.org/D39028 llvm-svn: 317278
86 lines
2.9 KiB
C++
86 lines
2.9 KiB
C++
//===- MachineBlockFrequencyInfo.h - MBB Frequency Analysis -----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Loops should be simplified before this analysis.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H
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#define LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H
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#include "llvm/ADT/Optional.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/Support/BlockFrequency.h"
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#include <cstdint>
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#include <memory>
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namespace llvm {
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template <class BlockT> class BlockFrequencyInfoImpl;
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class MachineBasicBlock;
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class MachineBranchProbabilityInfo;
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class MachineFunction;
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class MachineLoopInfo;
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class raw_ostream;
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/// MachineBlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation
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/// to estimate machine basic block frequencies.
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class MachineBlockFrequencyInfo : public MachineFunctionPass {
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using ImplType = BlockFrequencyInfoImpl<MachineBasicBlock>;
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std::unique_ptr<ImplType> MBFI;
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public:
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static char ID;
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MachineBlockFrequencyInfo();
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~MachineBlockFrequencyInfo() override;
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void getAnalysisUsage(AnalysisUsage &AU) const override;
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bool runOnMachineFunction(MachineFunction &F) override;
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/// calculate - compute block frequency info for the given function.
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void calculate(const MachineFunction &F,
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const MachineBranchProbabilityInfo &MBPI,
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const MachineLoopInfo &MLI);
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void releaseMemory() override;
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/// getblockFreq - Return block frequency. Return 0 if we don't have the
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/// information. Please note that initial frequency is equal to 1024. It means
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/// that we should not rely on the value itself, but only on the comparison to
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/// the other block frequencies. We do this to avoid using of floating points.
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///
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BlockFrequency getBlockFreq(const MachineBasicBlock *MBB) const;
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Optional<uint64_t> getBlockProfileCount(const MachineBasicBlock *MBB) const;
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Optional<uint64_t> getProfileCountFromFreq(uint64_t Freq) const;
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bool isIrrLoopHeader(const MachineBasicBlock *MBB);
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const MachineFunction *getFunction() const;
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const MachineBranchProbabilityInfo *getMBPI() const;
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void view(const Twine &Name, bool isSimple = true) const;
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// Print the block frequency Freq to OS using the current functions entry
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// frequency to convert freq into a relative decimal form.
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raw_ostream &printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const;
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// Convenience method that attempts to look up the frequency associated with
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// BB and print it to OS.
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raw_ostream &printBlockFreq(raw_ostream &OS,
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const MachineBasicBlock *MBB) const;
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uint64_t getEntryFreq() const;
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};
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} // end namespace llvm
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#endif // LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H
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