[clang] Set __GCC_*STRUCTIVE_SIZE on Aarch64

Before this change, we would set this to Clang's default of {64, 64}.

Now, we explicitly set it to {256, 64} which matches our ARM behavior
for ARMv8 targets and GCC's behavior for AArch64 targets.

Author: majnemer

clang/lib/Basic/Targets/AArch64.h

@@ -227,6 +227,11 @@ class LLVM_LIBRARY_VISIBILITY AArch64TargetInfo : public TargetInfo {
   bool validatePointerAuthKey(const llvm::APSInt &value) const override;
 
   const char *getBFloat16Mangling() const override { return "u6__bf16"; };
+
+  std::pair<unsigned, unsigned> hardwareInterferenceSizes() const override {
+    return std::make_pair(256, 64);
+  }
+
   bool hasInt128Type() const override;
 
   bool hasBitIntType() const override { return true; }

clang/test/Preprocessor/init-aarch64.c

@@ -125,8 +125,8 @@
 // AARCH64-NEXT: #define __FP_FAST_FMAF 1
 // AARCH64-NEXT: #define __FUNCTION_MULTI_VERSIONING_SUPPORT_LEVEL 202430
 // AARCH64-NEXT: #define __GCC_ASM_FLAG_OUTPUTS__ 1
-// AARCH64-NEXT: #define __GCC_CONSTRUCTIVE_SIZE {{.+}}
-// AARCH64-NEXT: #define __GCC_DESTRUCTIVE_SIZE {{.+}}
+// AARCH64-NEXT: #define __GCC_CONSTRUCTIVE_SIZE 64
+// AARCH64-NEXT: #define __GCC_DESTRUCTIVE_SIZE 256
 // AARCH64-NEXT: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_1 1
 // AARCH64-NEXT: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16 1
 // AARCH64-NEXT: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_2 1