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Output mov %REG = 0 instead of xor %REG, %REG, %REG to clear a 

register so that LiveVariable analysis is not confused.

llvm-svn: 10773
This commit is contained in:
Alkis Evlogimenos 2004-01-12 07:22:45 +00:00
parent 69fba00b85
commit 975c8bde79
1 changed files with 3 additions and 3 deletions
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6
llvm/lib/Target/X86/InstSelectSimple.cpp
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@ -1452,7 +1452,7 @@ void ISel::emitDivRemOperation(MachineBasicBlock *BB,
static const unsigned Regs[] ={ X86::AL , X86::AX , X86::EAX };
static const unsigned MovOpcode[]={ X86::MOVrr8, X86::MOVrr16, X86::MOVrr32 };
static const unsigned SarOpcode[]={ X86::SARir8, X86::SARir16, X86::SARir32 };
static const unsigned ClrOpcode[]={ X86::XORrr8, X86::XORrr16, X86::XORrr32 };
static const unsigned ClrOpcode[]={ X86::MOVir8, X86::MOVir16, X86::MOVir32 };
static const unsigned ExtRegs[] ={ X86::AH , X86::DX , X86::EDX };
static const unsigned DivOpcode[][4] = {
@ -1473,8 +1473,8 @@ void ISel::emitDivRemOperation(MachineBasicBlock *BB,
BMI(BB, IP, SarOpcode[Class], 2, ShiftResult).addReg(Op0Reg).addZImm(31);
BMI(BB, IP, MovOpcode[Class], 1, ExtReg).addReg(ShiftResult);
} else {
// If unsigned, emit a zeroing instruction... (reg = xor reg, reg)
BMI(BB, IP, ClrOpcode[Class], 2, ExtReg).addReg(ExtReg).addReg(ExtReg);
// If unsigned, emit a zeroing instruction... (reg = 0)
BMI(BB, IP, ClrOpcode[Class], 2, ExtReg).addZImm(0);
}
// Emit the appropriate divide or remainder instruction...