[clang] [Clang][ARM] Only try to redefine builtins for non-CUDA (PR #128222)

[Artem Belevich via cfe-commits]

================
@@ -27,6 +27,8 @@
 extern "C" {
 #endif
 
+#if !defined(__CUDA_ARCH__)
+
----------------
Artem-B wrote:

Unfortunately, this will be observable to any code that happens to need those builtins, and they are actually not provided by the compiler (i.e. `__has_builtin(__wfi)` would be host on the *host*).

In that case, any use of `__wfi()` in the host code will break compilation because host-side code will not be able to find it.

I think a more robust fix would be to provide only declarations for these maybe-builtin functions, so the compiler always sees the correct signature of the functions that are conditionally provided depending on `__has_builtin()`.





https://github.com/llvm/llvm-project/pull/128222