X86: change zext moves to use sub-register infrastructure.
32-bit writes on amd64 zero out the high bits of the corresponding 64-bit
register. LLVM makes use of this for zero-extension, but until now relied on
custom MCLowering and other code to fixup instructions. Now we have proper
handling of sub-registers, this can be done by creating SUBREG_TO_REG
instructions at selection-time.
Should be no change in functionality.
llvm-svn: 182921
diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index ed3677e..4f0c2f2 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -451,9 +451,6 @@
{ X86::MOVZX32rr16, X86::MOVZX32rm16, 0 },
{ X86::MOVZX32_NOREXrr8, X86::MOVZX32_NOREXrm8, 0 },
{ X86::MOVZX32rr8, X86::MOVZX32rm8, 0 },
- { X86::MOVZX64rr16, X86::MOVZX64rm16, 0 },
- { X86::MOVZX64rr32, X86::MOVZX64rm32, 0 },
- { X86::MOVZX64rr8, X86::MOVZX64rm8, 0 },
{ X86::PABSBrr128, X86::PABSBrm128, TB_ALIGN_16 },
{ X86::PABSDrr128, X86::PABSDrm128, TB_ALIGN_16 },
{ X86::PABSWrr128, X86::PABSWrm128, TB_ALIGN_16 },
@@ -1381,7 +1378,6 @@
case X86::MOVSX32rr8:
case X86::MOVZX32rr8:
case X86::MOVSX64rr8:
- case X86::MOVZX64rr8:
if (!TM.getSubtarget<X86Subtarget>().is64Bit())
// It's not always legal to reference the low 8-bit of the larger
// register in 32-bit mode.
@@ -1389,9 +1385,7 @@
case X86::MOVSX32rr16:
case X86::MOVZX32rr16:
case X86::MOVSX64rr16:
- case X86::MOVZX64rr16:
- case X86::MOVSX64rr32:
- case X86::MOVZX64rr32: {
+ case X86::MOVSX64rr32: {
if (MI.getOperand(0).getSubReg() || MI.getOperand(1).getSubReg())
// Be conservative.
return false;
@@ -1404,17 +1398,14 @@
case X86::MOVSX32rr8:
case X86::MOVZX32rr8:
case X86::MOVSX64rr8:
- case X86::MOVZX64rr8:
SubIdx = X86::sub_8bit;
break;
case X86::MOVSX32rr16:
case X86::MOVZX32rr16:
case X86::MOVSX64rr16:
- case X86::MOVZX64rr16:
SubIdx = X86::sub_16bit;
break;
case X86::MOVSX64rr32:
- case X86::MOVZX64rr32:
SubIdx = X86::sub_32bit;
break;
}