[clang] [AArch64][PAC] Support ptrauth builtins and -fptrauth-intrinsics. (PR #65996)

[Chuanqi Xu via cfe-commits]

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@@ -303,6 +303,10 @@ bool Module::directlyUses(const Module *Requested) {
   if (!Requested->Parent && Requested->Name == "_Builtin_stddef_max_align_t")
     return true;
 
+  // Anyone is allowed to use our builtin ptrauth.h and its accompanying module.
+  if (!Requested->Parent && Requested->Name == "ptrauth")
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ChuanqiXu9 wrote:

On the one hand, I don't think it is necessary to support modules in the first step. On the other hand, we can try to get the same semantics by adding new mechanism to modules. e.g., we can declare some modules are always directly usable in the module map.

https://github.com/llvm/llvm-project/pull/65996