[llvm-commits] [llvm] r49946 - /llvm/trunk/lib/Target/X86/X86InstrInfo.td

[Evan Cheng]

Author: evancheng
Date: Fri Apr 18 20:20:30 2008
New Revision: 49946

URL: http://llvm.org/viewvc/llvm-project?rev=49946&view=rev
Log:
xchg which references a memory operand does not need to lock prefix. Atomicity is guaranteed.

Modified:
    llvm/trunk/lib/Target/X86/X86InstrInfo.td

Modified: llvm/trunk/lib/Target/X86/X86InstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrInfo.td?rev=49946&r1=49945&r2=49946&view=diff

==============================================================================
--- llvm/trunk/lib/Target/X86/X86InstrInfo.td (original)
+++ llvm/trunk/lib/Target/X86/X86InstrInfo.td Fri Apr 18 20:20:30 2008
@@ -2543,6 +2543,21 @@
 // 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 @@
                [(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),