[clang] ObjcRuntime.h: Add mips64, aarch64, and riscv64 to non-legacy dispatch (PR #76694)

[Hugo Melder via cfe-commits]

https://github.com/hmelder created https://github.com/llvm/llvm-project/pull/76694

This PR updates the list of architectures for which libobjc2 has fast-path objc_msgSend implementations.

Related to: https://github.com/gnustep/libobjc2/pull/261

>From 97a9a2753c52d6b377d929a4a6e717ab3c69b68d Mon Sep 17 00:00:00 2001
From: hmelder <service at hugomelder.com>
Date: Tue, 2 Jan 2024 01:46:19 +0100
Subject: [PATCH] Add mips64, aarch64, and riscv64 to ObjcRuntime dispatch

---
 clang/include/clang/Basic/ObjCRuntime.h | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/clang/include/clang/Basic/ObjCRuntime.h b/clang/include/clang/Basic/ObjCRuntime.h
index 500b2462f00773..29392ad0a0f577 100644
--- a/clang/include/clang/Basic/ObjCRuntime.h
+++ b/clang/include/clang/Basic/ObjCRuntime.h
@@ -101,10 +101,17 @@ class ObjCRuntime {
     // The GNUstep runtime uses a newer dispatch method by default from
     // version 1.6 onwards
     if (getKind() == GNUstep && getVersion() >= VersionTuple(1, 6)) {
-      if (Arch == llvm::Triple::arm ||
-          Arch == llvm::Triple::x86 ||
-          Arch == llvm::Triple::x86_64)
-        return false;
+      switch (Arch) {
+        case llvm::Triple::arm:
+        case llvm::Triple::x86:
+        case llvm::Triple::x86_64:
+        case llvm::Triple::aarch64:
+        case llvm::Triple::mips64:
+        case llvm::Triple::riscv64:
+          return false;
+        default:
+          return true;
+      }
     }
     else if ((getKind() ==  MacOSX) && isNonFragile() &&
              (getVersion() >= VersionTuple(10, 0)) &&