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| author | Evan Cheng <evan.cheng@apple.com> | 2011-04-01 22:09:28 +0000 |
|---|---|---|
| committer | Evan Cheng <evan.cheng@apple.com> | 2011-04-01 22:09:28 +0000 |
| commit | 0539c159fb6e3f8d09d4790d8d6a4615c26d3e98 (patch) | |
| tree | f3880efee5ef9b2d6b16e8ec1bf9598c3ac6d397 /lib | |
| parent | ad8180a0b85cbb66d30ba011d358279e6d461a16 (diff) | |
| download | llvm-0539c159fb6e3f8d09d4790d8d6a4615c26d3e98.tar.gz llvm-0539c159fb6e3f8d09d4790d8d6a4615c26d3e98.tar.bz2 llvm-0539c159fb6e3f8d09d4790d8d6a4615c26d3e98.tar.xz | |
Avoid de-referencing pass beginning of a basic block. No small test case possible. rdar://9216009
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128743 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Target/ARM/ARMConstantIslandPass.cpp | 39 |
1 files changed, 21 insertions, 18 deletions
diff --git a/lib/Target/ARM/ARMConstantIslandPass.cpp b/lib/Target/ARM/ARMConstantIslandPass.cpp index 13d1b33d11..baf95a33dd 100644 --- a/lib/Target/ARM/ARMConstantIslandPass.cpp +++ b/lib/Target/ARM/ARMConstantIslandPass.cpp @@ -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; + } } } } |