Working on reconciling out-of-tree patches to compiler-rt for building for iOS.

[beanz]

Summary

This is one of many changes needed for compiler-rt to get it building on iOS.

Darwin doesn't have _Unwind_VRS_Get, instead use _Unwind_GetIP directly.

Note: this change does not enable building for iOS, as there are more changes to come.

[beanz]

Adding Kuba and Justin for review.

[samsonov]

lib/sanitizer_common/sanitizer_unwind_posix_libcdep.cc

85

Why not !SANITIZER_MAC?

[beanz]

Updating based on feedback from samsonov.

[samsonov]

LGTM

lib/sanitizer_common/sanitizer_unwind_posix_libcdep.cc

 #define UNWIND_STOP _URC_END_OF_STACK
 #define UNWIND_CONTINUE _URC_NO_REASON
 #else
 #define UNWIND_STOP _URC_NORMAL_STOP
 #define UNWIND_CONTINUE _URC_NO_REASON
 #endif
 
 uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
-#ifdef __arm__
+#if defined(__arm__) && !defined(__APPLE__)
   uptr val;
   _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
       15 /* r15 = PC */, _UVRSD_UINT32, &val);
   CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
   // Clear the Thumb bit.
   return val & ~(uptr)1;
 #else
   return _Unwind_GetIP(ctx);