[clang] [clang-tools-extra] [llvm] [Clang] Fix linker error for function multiversioning (PR #71706)

[Tom Honermann via cfe-commits]

================
@@ -4282,10 +4300,19 @@ llvm::Constant *CodeGenModule::GetOrCreateMultiVersionResolver(GlobalDecl GD) {
   // Holds the name of the resolver, in ifunc mode this is the ifunc (which has
   // a separate resolver).
   std::string ResolverName = MangledName;
-  if (getTarget().supportsIFunc())
-    ResolverName += ".ifunc";
-  else if (FD->isTargetMultiVersion())
+  if (getTarget().supportsIFunc()) {
+    // In Aarch64, default versions of multiversioned functions are mangled to
+    // their 'normal' assembly name. This deviates from other targets which
+    // append a '.default' string. As a result we need to continue appending
+    // .ifunc in Aarch64.
+    // FIXME: Should Aarch64 mangling for 'default' multiversion function and
+    // in turn ifunc function match that of other targets?
----------------
tahonermann wrote:

@DanielKristofKiss, please ensure this comment and FIXME is addressed/removed by your follow up patch.

https://github.com/llvm/llvm-project/pull/71706