[llvm] [X86][APX] Try to replace non-NF with NF instructions when optimizeCompareInstr (PR #130488)

[Shengchen Kan via llvm-commits]

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@@ -5441,6 +5443,16 @@ bool X86InstrInfo::optimizeCompareInstr(MachineInstr &CmpInstr, Register SrcReg,
           continue;
         }
 
+        // Try to replace non-NF with NF instructions.
+        if (HasNF && Inst.registerDefIsDead(X86::EFLAGS, TRI)) {
+          unsigned NewOp = X86::getNFVariant(Inst.getOpcode());
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KanRobert wrote:

Would it introduce more times of table lookup? 

https://github.com/llvm/llvm-project/pull/130488