diff options
Diffstat (limited to 'llvm/lib/Target/X86/X86InstrInfo.td')
| -rw-r--r-- | llvm/lib/Target/X86/X86InstrInfo.td | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/llvm/lib/Target/X86/X86InstrInfo.td b/llvm/lib/Target/X86/X86InstrInfo.td index 9b69018fa8b..aac9f38c8a9 100644 --- a/llvm/lib/Target/X86/X86InstrInfo.td +++ b/llvm/lib/Target/X86/X86InstrInfo.td @@ -3734,18 +3734,21 @@ let Defs = [EFLAGS], isReMaterializable = 1, isAsCheapAsAMove = 1, def MOV8r0 : I<0x30, MRMInitReg, (outs GR8 :$dst), (ins), "xor{b}\t$dst, $dst", [(set GR8:$dst, 0)]>; + +// We want to rewrite MOV16r0 in terms of MOV32r0, because it's a smaller +// encoding and avoids a partial-register update sometimes, but doing so +// at isel time interferes with rematerialization in the current register +// allocator. For now, this is rewritten when the instruction is lowered +// to an MCInst. +def MOV16r0 : I<0x31, MRMInitReg, (outs GR16:$dst), (ins), + "", + [(set GR16:$dst, 0)]>, OpSize; def MOV32r0 : I<0x31, MRMInitReg, (outs GR32:$dst), (ins), "xor{l}\t$dst, $dst", [(set GR32:$dst, 0)]>; } -// Use xorl instead of xorw since we don't care about the high 16 bits, -// it's smaller, and it avoids a partial-register update. -let AddedComplexity = 1 in -def : Pat<(i16 0), - (EXTRACT_SUBREG (MOV32r0), x86_subreg_16bit)>; - //===----------------------------------------------------------------------===// // Thread Local Storage Instructions // |
