[clang] [Clang][ARM][Sema] Check validity of ldrexd/strexd builtin calls (PR #164919)

[Simon Tatham via cfe-commits]

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@@ -24,3 +24,27 @@ int test_strex(char *addr) {
   res |= __builtin_arm_strex(42, (long long *)addr); // expected-error {{address argument to load or store exclusive builtin must be a pointer to 1,2 or 4 byte type}}
   return res;
 }
+
+int test_ldrexd(char *addr) {
+  int sum = 0;
+  sum += __builtin_arm_ldrexd(addr); // expected-error {{load and store exclusive builtins are not available on this architecture}}
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statham-arm wrote:

Wow, that's surely a bug in Tablegen!

I especially like the way that the complaint "Diagnostics should not start with a capital letter" starts with a capital letter :slightly_smiling_face: 

I'm happy with 'eight-byte'. It might not be worded exactly the same as the other messages, but it conveys the important information.

https://github.com/llvm/llvm-project/pull/164919