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//===-- BranchFolding.h - Fold machine code branch instructions -*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_CODEGEN_BRANCHFOLDING_H
#define LLVM_LIB_CODEGEN_BRANCHFOLDING_H
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/CodeGen/LivePhysRegs.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/Support/BlockFrequency.h"
#include <vector>
namespace llvm {
class MachineBlockFrequencyInfo;
class MachineBranchProbabilityInfo;
class MachineFunction;
class MachineModuleInfo;
class MachineLoopInfo;
class TargetInstrInfo;
class TargetRegisterInfo;
class LLVM_LIBRARY_VISIBILITY BranchFolder {
public:
class MBFIWrapper;
explicit BranchFolder(bool defaultEnableTailMerge,
bool CommonHoist,
MBFIWrapper &MBFI,
const MachineBranchProbabilityInfo &MBPI,
// Min tail length to merge. Defaults to commandline
// flag. Ignored for optsize.
unsigned MinCommonTailLength = 0);
bool OptimizeFunction(MachineFunction &MF, const TargetInstrInfo *tii,
const TargetRegisterInfo *tri, MachineModuleInfo *mmi,
MachineLoopInfo *mli = nullptr,
bool AfterPlacement = false);
private:
class MergePotentialsElt {
unsigned Hash;
MachineBasicBlock *Block;
public:
MergePotentialsElt(unsigned h, MachineBasicBlock *b)
: Hash(h), Block(b) {}
unsigned getHash() const { return Hash; }
MachineBasicBlock *getBlock() const { return Block; }
void setBlock(MachineBasicBlock *MBB) {
Block = MBB;
}
bool operator<(const MergePotentialsElt &) const;
};
typedef std::vector<MergePotentialsElt>::iterator MPIterator;
std::vector<MergePotentialsElt> MergePotentials;
SmallPtrSet<const MachineBasicBlock*, 2> TriedMerging;
DenseMap<const MachineBasicBlock *, int> FuncletMembership;
class SameTailElt {
MPIterator MPIter;
MachineBasicBlock::iterator TailStartPos;
public:
SameTailElt(MPIterator mp, MachineBasicBlock::iterator tsp)
: MPIter(mp), TailStartPos(tsp) {}
MPIterator getMPIter() const {
return MPIter;
}
MergePotentialsElt &getMergePotentialsElt() const {
return *getMPIter();
}
MachineBasicBlock::iterator getTailStartPos() const {
return TailStartPos;
}
unsigned getHash() const {
return getMergePotentialsElt().getHash();
}
MachineBasicBlock *getBlock() const {
return getMergePotentialsElt().getBlock();
}
bool tailIsWholeBlock() const {
return TailStartPos == getBlock()->begin();
}
void setBlock(MachineBasicBlock *MBB) {
getMergePotentialsElt().setBlock(MBB);
}
void setTailStartPos(MachineBasicBlock::iterator Pos) {
TailStartPos = Pos;
}
};
std::vector<SameTailElt> SameTails;
bool AfterBlockPlacement;
bool EnableTailMerge;
bool EnableHoistCommonCode;
bool UpdateLiveIns;
unsigned MinCommonTailLength;
const TargetInstrInfo *TII;
const TargetRegisterInfo *TRI;
MachineModuleInfo *MMI;
MachineLoopInfo *MLI;
LivePhysRegs LiveRegs;
public:
/// \brief This class keeps track of branch frequencies of newly created
/// blocks and tail-merged blocks.
class MBFIWrapper {
public:
MBFIWrapper(const MachineBlockFrequencyInfo &I) : MBFI(I) {}
BlockFrequency getBlockFreq(const MachineBasicBlock *MBB) const;
void setBlockFreq(const MachineBasicBlock *MBB, BlockFrequency F);
raw_ostream &printBlockFreq(raw_ostream &OS,
const MachineBasicBlock *MBB) const;
raw_ostream &printBlockFreq(raw_ostream &OS,
const BlockFrequency Freq) const;
private:
const MachineBlockFrequencyInfo &MBFI;
DenseMap<const MachineBasicBlock *, BlockFrequency> MergedBBFreq;
};
private:
MBFIWrapper &MBBFreqInfo;
const MachineBranchProbabilityInfo &MBPI;
bool TailMergeBlocks(MachineFunction &MF);
bool TryTailMergeBlocks(MachineBasicBlock* SuccBB,
MachineBasicBlock* PredBB,
unsigned MinCommonTailLength);
void setCommonTailEdgeWeights(MachineBasicBlock &TailMBB);
void ReplaceTailWithBranchTo(MachineBasicBlock::iterator OldInst,
MachineBasicBlock *NewDest);
MachineBasicBlock *SplitMBBAt(MachineBasicBlock &CurMBB,
MachineBasicBlock::iterator BBI1,
const BasicBlock *BB);
unsigned ComputeSameTails(unsigned CurHash, unsigned minCommonTailLength,
MachineBasicBlock *SuccBB,
MachineBasicBlock *PredBB);
void RemoveBlocksWithHash(unsigned CurHash, MachineBasicBlock* SuccBB,
MachineBasicBlock* PredBB);
bool CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB,
MachineBasicBlock *SuccBB,
unsigned maxCommonTailLength,
unsigned &commonTailIndex);
bool OptimizeBranches(MachineFunction &MF);
bool OptimizeBlock(MachineBasicBlock *MBB);
void RemoveDeadBlock(MachineBasicBlock *MBB);
bool HoistCommonCode(MachineFunction &MF);
bool HoistCommonCodeInSuccs(MachineBasicBlock *MBB);
};
}
#endif /* LLVM_CODEGEN_BRANCHFOLDING_HPP */
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