[clang] [Clang][AArch64] Fix Pure Scalables Types argument passing and return (PR #112747)

[Eli Friedman via cfe-commits]

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@@ -353,6 +427,17 @@ AArch64ABIInfo::classifyArgumentType(QualType Ty, bool IsVariadic,
         nullptr, true, Align);
   }
 
+  // In AAPCS named arguments of a Pure Scalable Type are passed expanded in
+  // registers, or indirectly if there are not enough registers.
+  if (Kind == AArch64ABIKind::AAPCS && !IsVariadic) {
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efriedma-quic wrote:

I'm pretty sure "IsVariadic" is whether the function type is variadic, not whether the argument is named.

https://github.com/llvm/llvm-project/pull/112747