[x86] put nops into the WriteNop class and customize for Jaguar
1. Given that we already have a classification bucket with 'nop' in the name,
that's where 'nop' belongs. Right now, it's only used for prefix bytes and 'pause'.
2. Make the latency of this class '1' for Jaguar to tell the scheduler (and presumably
llvm-mca) how to model the resource requirements better even though a nop has no
dependencies.
Differential Revision: https://reviews.llvm.org/D44608
llvm-svn: 327853
diff --git a/llvm/lib/Target/X86/X86InstrFPStack.td b/llvm/lib/Target/X86/X86InstrFPStack.td
index 619b399..18071c6 100644
--- a/llvm/lib/Target/X86/X86InstrFPStack.td
+++ b/llvm/lib/Target/X86/X86InstrFPStack.td
@@ -667,10 +667,10 @@
} // Defs = [FPSW]
} // SchedRW
-// Operandless floating-point instructions for the disassembler.
-let SchedRW = [WriteMicrocoded] in {
-def FNOP : I<0xD9, MRM_D0, (outs), (ins), "fnop", [], IIC_FNOP>;
+// Operand-less floating-point instructions for the disassembler.
+def FNOP : I<0xD9, MRM_D0, (outs), (ins), "fnop", [], IIC_FNOP>, Sched<[WriteNop]>;
+let SchedRW = [WriteMicrocoded] in {
let Defs = [FPSW] in {
def WAIT : I<0x9B, RawFrm, (outs), (ins), "wait", [], IIC_WAIT>;
def FXAM : I<0xD9, MRM_E5, (outs), (ins), "fxam", [], IIC_FXAM>;