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AArch64: Consolidate branch inversion logic

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llvm-svn: 277431
This commit is contained in:
Matt Arsenault 2016-08-02 08:30:06 +00:00
parent 3d29ff4eb8
commit b4071777e1
1 changed files with 23 additions and 21 deletions
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44
lib/Target/AArch64/AArch64BranchRelaxation.cpp
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@ -73,8 +73,10 @@ class AArch64BranchRelaxation : public MachineFunctionPass {
MachineBasicBlock *splitBlockBeforeInstr(MachineInstr &MI);
void adjustBlockOffsets(MachineBasicBlock &MBB);
bool isBlockInRange(const MachineInstr &MI, const MachineBasicBlock &BB) const;
void invertConditionalBranch(MachineInstr &MI) const;
unsigned insertInvertedConditionalBranch(MachineBasicBlock &MBB,
unsigned insertInvertedConditionalBranch(MachineBasicBlock &SrcBB,
MachineBasicBlock::iterator InsPt,
const DebugLoc &DL,
const MachineInstr &OldBr,
MachineBasicBlock &NewDestBB) const;
unsigned insertUnconditionalBranch(MachineBasicBlock &MBB,
@ -226,7 +228,7 @@ AArch64BranchRelaxation::splitBlockBeforeInstr(MachineInstr &MI) {
// Note the new unconditional branch is not being recorded.
// There doesn't seem to be meaningful DebugInfo available; this doesn't
// correspond to anything in the source.
BuildMI(OrigBB, DebugLoc(), TII->get(AArch64::B)).addMBB(NewBB);
insertUnconditionalBranch(*OrigBB, *NewBB, DebugLoc());
// Insert an entry into BlockInfo to align it properly with the block numbers.
BlockInfo.insert(BlockInfo.begin() + NewBB->getNumber(), BasicBlockInfo());
@ -315,25 +317,19 @@ static inline void invertBccCondition(MachineInstr &MI) {
CCOp.setImm(AArch64CC::getInvertedCondCode(CC));
}
/// Invert the branch condition of \p MI and change the destination to \p NewB
void AArch64BranchRelaxation::invertConditionalBranch(MachineInstr &MI) const {
MI.setDesc(TII->get(getOppositeConditionOpcode(MI.getOpcode())));
if (MI.getOpcode() == AArch64::Bcc)
invertBccCondition(MI);
}
/// Insert a conditional branch at the end of \p MBB to \p NewDestBB, using the
/// inverse condition of branch \p OldBr.
/// \returns The number of bytes added to the block.
unsigned AArch64BranchRelaxation::insertInvertedConditionalBranch(
MachineBasicBlock &MBB,
MachineBasicBlock &SrcMBB,
MachineBasicBlock::iterator InsPt,
const DebugLoc &DL,
const MachineInstr &OldBr,
MachineBasicBlock &NewDestBB) const {
unsigned OppositeCondOpc = getOppositeConditionOpcode(OldBr.getOpcode());
MachineInstrBuilder MIB =
BuildMI(&MBB, OldBr.getDebugLoc(), TII->get(OppositeCondOpc))
BuildMI(SrcMBB, InsPt, DL, TII->get(OppositeCondOpc))
.addOperand(OldBr.getOperand(0));
unsigned Opc = OldBr.getOpcode();
@ -414,8 +410,13 @@ bool AArch64BranchRelaxation::fixupConditionalBranch(MachineInstr &MI) {
DEBUG(dbgs() << " Invert condition and swap its destination with "
<< *BMI);
changeBranchDestBlock(*BMI, *DestBB);
invertConditionalBranch(MI);
changeBranchDestBlock(MI, *NewDest);
int NewSize =
insertInvertedConditionalBranch(*MBB, MI.getIterator(),
MI.getDebugLoc(), MI, *NewDest);
int OldSize = TII->getInstSizeInBytes(MI);
BlockInfo[MBB->getNumber()].Size += (NewSize - OldSize);
MI.eraseFromParent();
return true;
}
}
@ -447,15 +448,16 @@ bool AArch64BranchRelaxation::fixupConditionalBranch(MachineInstr &MI) {
<< ", invert condition and change dest. to BB#"
<< NextBB.getNumber() << '\n');
// Insert a new conditional branch and a new unconditional branch.
BlockInfo[MBB->getNumber()].Size
+= insertInvertedConditionalBranch(*MBB, MI, NextBB);
unsigned &MBBSize = BlockInfo[MBB->getNumber()].Size;
BlockInfo[MBB->getNumber()].Size +=
insertUnconditionalBranch(*MBB, *DestBB, MI.getDebugLoc());
// Insert a new conditional branch and a new unconditional branch.
MBBSize += insertInvertedConditionalBranch(*MBB, MBB->end(),
MI.getDebugLoc(), MI, NextBB);
MBBSize += insertUnconditionalBranch(*MBB, *DestBB, MI.getDebugLoc());
// Remove the old conditional branch. It may or may not still be in MBB.
BlockInfo[MBB->getNumber()].Size -= TII->getInstSizeInBytes(MI);
MBBSize -= TII->getInstSizeInBytes(MI);
MI.eraseFromParent();
// Finally, keep the block offsets up to date.