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xchg which references a memory operand does not need to lock prefix. Atomicity is guaranteed. 

llvm-svn: 49946
This commit is contained in:
Evan Cheng 2008-04-19 01:20:30 +00:00
parent 41eb949aaf
commit 7f4240a47c
1 changed files with 15 additions and 14 deletions
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29
llvm/lib/Target/X86/X86InstrInfo.td
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@ -2543,6 +2543,21 @@ def EH_RETURN : I<0xC3, RawFrm, (outs), (ins GR32:$addr),
// Atomic support
//
// Atomic swap. These are just normal xchg instructions. But since a memory
// operand is referenced, the atomicity is ensured.
let Constraints = "$val = $dst", Defs = [EFLAGS] in {
def XCHG32rm : I<0x87, MRMSrcMem, (outs GR32:$dst), (ins i32mem:$ptr, GR32:$val),
"xchg{l}\t{$val, $ptr|$ptr, $val}",
[(set GR32:$dst, (atomic_swap_32 addr:$ptr, GR32:$val))]>;
def XCHG16rm : I<0x87, MRMSrcMem, (outs GR16:$dst), (ins i16mem:$ptr, GR16:$val),
"xchg{w}\t{$val, $ptr|$ptr, $val}",
[(set GR16:$dst, (atomic_swap_16 addr:$ptr, GR16:$val))]>,
OpSize;
def XCHG8rm : I<0x86, MRMSrcMem, (outs GR8:$dst), (ins i8mem:$ptr, GR8:$val),
"xchg{b}\t{$val, $ptr|$ptr, $val}",
[(set GR8:$dst, (atomic_swap_8 addr:$ptr, GR8:$val))]>;
}
// Atomic compare and swap.
let Defs = [EAX, EFLAGS], Uses = [EAX] in {
def LCMPXCHG32 : I<0xB1, MRMDestMem, (outs), (ins i32mem:$ptr, GR32:$swap),
@ -2566,20 +2581,6 @@ def LCMPXCHG8 : I<0xB0, MRMDestMem, (outs), (ins i8mem:$ptr, GR8:$swap),
[(X86cas addr:$ptr, GR8:$swap, 1)]>, TB, LOCK;
}
// Atomic swap
let Constraints = "$val = $dst", Defs = [EFLAGS] in {
def LXCHG32 : I<0x87, MRMSrcMem, (outs GR32:$dst), (ins i32mem:$ptr, GR32:$val),
"lock xchg{l}\t{$val, $ptr|$ptr, $val}",
[(set GR32:$dst, (atomic_swap_32 addr:$ptr, GR32:$val))]>, LOCK;
def LXCHG16 : I<0x87, MRMSrcMem, (outs GR16:$dst), (ins i16mem:$ptr, GR16:$val),
"lock xchg{w}\t{$val, $ptr|$ptr, $val}",
[(set GR16:$dst, (atomic_swap_16 addr:$ptr, GR16:$val))]>,
OpSize, LOCK;
def LXCHG8 : I<0x86, MRMSrcMem, (outs GR8:$dst), (ins i8mem:$ptr, GR8:$val),
"lock xchg{b}\t{$val, $ptr|$ptr, $val}",
[(set GR8:$dst, (atomic_swap_8 addr:$ptr, GR8:$val))]>, LOCK;
}
// Atomic exchange and add
let Constraints = "$val = $dst", Defs = [EFLAGS] in {
def LXADD32 : I<0xC1, MRMSrcMem, (outs GR32:$dst), (ins i32mem:$ptr, GR32:$val),