Output mov %REG = 0 instead of xor %REG, %REG, %REG to clear a
register so that LiveVariable analysis is not confused.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10773 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/InstSelectSimple.cpp b/lib/Target/X86/InstSelectSimple.cpp
index 0cd2481..745c219 100644
--- a/lib/Target/X86/InstSelectSimple.cpp
+++ b/lib/Target/X86/InstSelectSimple.cpp
@@ -1452,7 +1452,7 @@
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 @@
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...