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It's not safe to rematerialize MOV32r0 etc. by simply cloning the original

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instruction. These are implemented with xor which will modify the conditional
code. They should be rematerialized as move instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41802 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-09-10 20:48:53 +00:00
parent 9c7a9f186c
commit b0869ed44d
1 changed files with 22 additions and 3 deletions
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25
lib/Target/X86/X86RegisterInfo.cpp
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@ -265,9 +265,28 @@ void X86RegisterInfo::reMaterialize(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I,
unsigned DestReg,
const MachineInstr *Orig) const {
MachineInstr *MI = Orig->clone();
MI->getOperand(0).setReg(DestReg);
MBB.insert(I, MI);
// MOV32r0 etc. are implemented with xor which clobbers condition code.
// Re-materialize them as movri instructions to avoid side effects.
switch (Orig->getOpcode()) {
case X86::MOV8r0:
BuildMI(MBB, I, TII.get(X86::MOV8ri), DestReg).addImm(0);
break;
case X86::MOV16r0:
BuildMI(MBB, I, TII.get(X86::MOV16ri), DestReg).addImm(0);
break;
case X86::MOV32r0:
BuildMI(MBB, I, TII.get(X86::MOV32ri), DestReg).addImm(0);
break;
case X86::MOV64r0:
BuildMI(MBB, I, TII.get(X86::MOV64ri32), DestReg).addImm(0);
break;
default: {
MachineInstr *MI = Orig->clone();
MI->getOperand(0).setReg(DestReg);
MBB.insert(I, MI);
break;
}
}
}
static const MachineInstrBuilder &FuseInstrAddOperand(MachineInstrBuilder &MIB,