[llvm] [X86] Avoid useless DomTree in flags copy lowering (PR #97628)

[Phoebe Wang via llvm-commits]

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@@ -688,7 +707,7 @@ bool X86FlagsCopyLoweringPass::runOnMachineFunction(MachineFunction &MF) {
       }
 #endif
 
-  return true;
+  return !Copies.empty();
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phoebewang wrote:

Shouldn't we always return `true` with checking `MI.getOperand(0).getReg() == X86::EFLAGS`?

https://github.com/llvm/llvm-project/pull/97628