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Avoid de-referencing pass beginning of a basic block. No small test case possible. rdar://9216009

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128743 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2011-04-01 22:09:28 +00:00
parent ad8180a0b8
commit 0539c159fb
1 changed files with 21 additions and 18 deletions
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39
lib/Target/ARM/ARMConstantIslandPass.cpp
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@ -1650,24 +1650,27 @@ bool ARMConstantIslands::OptimizeThumb2Branches(MachineFunction &MF) {
unsigned BrOffset = GetOffsetOf(Br.MI) + 4 - 2;
unsigned DestOffset = BBOffsets[DestBB->getNumber()];
if (BrOffset < DestOffset && (DestOffset - BrOffset) <= 126) {
MachineBasicBlock::iterator CmpMI = Br.MI; --CmpMI;
if (CmpMI->getOpcode() == ARM::tCMPi8) {
unsigned Reg = CmpMI->getOperand(0).getReg();
Pred = llvm::getInstrPredicate(CmpMI, PredReg);
if (Pred == ARMCC::AL &&
CmpMI->getOperand(1).getImm() == 0 &&
isARMLowRegister(Reg)) {
MachineBasicBlock *MBB = Br.MI->getParent();
MachineInstr *NewBR =
BuildMI(*MBB, CmpMI, Br.MI->getDebugLoc(), TII->get(NewOpc))
.addReg(Reg).addMBB(DestBB, Br.MI->getOperand(0).getTargetFlags());
CmpMI->eraseFromParent();
Br.MI->eraseFromParent();
Br.MI = NewBR;
BBSizes[MBB->getNumber()] -= 2;
AdjustBBOffsetsAfter(MBB, -2);
++NumCBZ;
MadeChange = true;
MachineBasicBlock::iterator CmpMI = Br.MI;
if (CmpMI != Br.MI->getParent()->begin()) {
--CmpMI;
if (CmpMI->getOpcode() == ARM::tCMPi8) {
unsigned Reg = CmpMI->getOperand(0).getReg();
Pred = llvm::getInstrPredicate(CmpMI, PredReg);
if (Pred == ARMCC::AL &&
CmpMI->getOperand(1).getImm() == 0 &&
isARMLowRegister(Reg)) {
MachineBasicBlock *MBB = Br.MI->getParent();
MachineInstr *NewBR =
BuildMI(*MBB, CmpMI, Br.MI->getDebugLoc(), TII->get(NewOpc))
.addReg(Reg).addMBB(DestBB,Br.MI->getOperand(0).getTargetFlags());
CmpMI->eraseFromParent();
Br.MI->eraseFromParent();
Br.MI = NewBR;
BBSizes[MBB->getNumber()] -= 2;
AdjustBBOffsetsAfter(MBB, -2);
++NumCBZ;
MadeChange = true;
}
}
}
}