[clang] [llvm] [IR][IPO] Don't rewrite the signature of optnone functions (PR #211804)

[Joseph Huber via cfe-commits]

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@@ -2921,6 +2921,12 @@ bool Attributor::isValidFunctionSignatureRewrite(
     return false;
 
   Function *Fn = Arg.getParent();
+  if (!Fn->canChangeSignature()) {
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jhuber6 wrote:

I took a closer look, and the attributor already gates `optnone` functions on `shouldInitialize`, so this was a complete no-op. I've dropped it for now, we can investigate allowing the attributor to search through `optnone` functions later.

https://github.com/llvm/llvm-project/pull/211804