Define the x86 pause instruction.

[oota-llvm.git] / lib / Target / X86 / X86InstrSSE.td

diff --git a/lib/Target/X86/X86InstrSSE.td b/lib/Target/X86/X86InstrSSE.td
index 0f782c9a8fde14824a9db8b481fa41b020cd9850..829f65c4623f01f5ae40b73f03206a6f32d0b65f 100644 (file)
--- a/lib/Target/X86/X86InstrSSE.td
+++ b/lib/Target/X86/X86InstrSSE.td
@@ -2417,6 +2417,10 @@ def LFENCE : I<0xAE, MRM_E8, (outs), (ins),
 def MFENCE : I<0xAE, MRM_F0, (outs), (ins),
                "mfence", [(int_x86_sse2_mfence)]>, TB, Requires<[HasSSE2]>;
 
+// Pause. This "instruction" is encoded as "rep; nop", so even though it
+// was introduced with SSE2, it's backward compabitle.
+def PAUSE : I<0x90, RawFrm, (outs), (ins), "pause", []>, REP;
+
 //TODO: custom lower this so as to never even generate the noop
 def : Pat<(membarrier (i8 imm), (i8 imm), (i8 imm), (i8 imm),
            (i8 0)), (NOOP)>;