[llvm] [PAC][InstCombine] Replace auth+sign with resign (PR #130807)

[Kristof Beyls via llvm-commits]

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@@ -2978,6 +2978,29 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
         Intrinsic::getOrInsertDeclaration(II->getModule(), NewIntrin);
     return CallInst::Create(NewFn, CallArgs);
   }
+  case Intrinsic::ptrauth_sign: {
+    // auth + sign can be replaced with resign, which prevents unsafe
+    // spills and reloads of intermediate authenticated value.
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kbeyls wrote:

Thanks!
After I wrote my initial comment above I wondered if this is the first peephole pattern added to InstCombine that is implemented because of security reasons rather than because of performance reasons.
Anyway thanks for that improved comment!

https://github.com/llvm/llvm-project/pull/130807