[llvm] [AArch64] Don't tail call memset if it would convert to a bzero. (PR #98969)

[Eli Friedman via llvm-commits]

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@@ -144,7 +145,16 @@ bool attributesPermitTailCall(const Function *F, const Instruction *I,
 /// optimization.
 bool returnTypeIsEligibleForTailCall(const Function *F, const Instruction *I,
                                      const ReturnInst *Ret,
-                                     const TargetLoweringBase &TLI);
+                                     const TargetLoweringBase &TLI,
+                                     bool ReturnsFirstArg = false);
+
+/// Check whether B is a bitcast of a pointer type to another pointer type,
+/// which is equal to A.
+bool isPointerBitcastEqualTo(const Value *A, const Value *B);
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efriedma-quic wrote:

Is `isPointerBitcastEqualTo` really necessary?  With opaque pointer types, we should never see a bitcast like this.

https://github.com/llvm/llvm-project/pull/98969