[llvm] Add option to turn off optimization for X86 assembler (PR #75895)

[Craig Topper via llvm-commits]

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@@ -3670,11 +3674,11 @@ bool X86AsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
 }
 
 bool X86AsmParser::processInstruction(MCInst &Inst, const OperandVector &Ops) {
-  if (ForcedVEXEncoding != VEXEncoding_VEX3 &&
+  if (AsmOptimize && ForcedVEXEncoding != VEXEncoding_VEX3 &&
       X86::optimizeInstFromVEX3ToVEX2(Inst, MII.get(Inst.getOpcode())))
     return true;
 
-  if (X86::optimizeShiftRotateWithImmediateOne(Inst))
+  if (AsmOptimize && X86::optimizeShiftRotateWithImmediateOne(Inst))
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topperc wrote:

@kongy does your assembler not optimize shifts/rotates by 1 to use the short form? That seems like a pretty basic optimization that has been around for x86 for a very long time.

https://github.com/llvm/llvm-project/pull/75895