[libcxxabi] Make new preprocessor guards for SJLJ and ARM_EHABI

[jroelofs]

Summary

This is in preparation to commit ARM EHABI support. Not functional change intended.

[jroelofs]

(forgot to cc cfe-commits)

[jroelofs]

It just occurred to me that these should be called LIBUNWIND_* because they're part of the unwinder, and not actually libcxxabi.

[jroelofs]

Renamed the guards: s/LIBCXXABI/LIBUNWIND/

include/unwind.h

 #include <stddef.h>
 
 #if defined(__APPLE__)
 #define LIBUNWIND_UNAVAIL __attribute__ (( unavailable ))
 #else
 #define LIBUNWIND_UNAVAIL
 #endif
 
+#if defined(__USING_SJLJ_EXCEPTIONS__)
+#  define LIBCXXABI_SJLJ 1
+#else
+#  define LIBCXXABI_SJLJ 0
+#endif
+
+#if __arm__ && !LIBCXXABI_SJLJ
+#  define LIBCXXABI_ARM_EHABI 1
+#else
+#  define LIBCXXABI_ARM_EHABI 0
+#endif
+
 typedef enum {
   _URC_NO_REASON = 0,
   _URC_FOREIGN_EXCEPTION_CAUGHT = 1,
   _URC_FATAL_PHASE2_ERROR = 2,
   _URC_FATAL_PHASE1_ERROR = 3,
   _URC_NORMAL_STOP = 4,
   _URC_END_OF_STACK = 5,
   _URC_HANDLER_FOUND = 6,

 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 //
 // The following are the base functions documented by the C++ ABI
 //
-#if __arm__
+#if LIBCXXABI_SJLJ
 extern _Unwind_Reason_Code
     _Unwind_SjLj_RaiseException(struct _Unwind_Exception *exception_object);
 extern void _Unwind_SjLj_Resume(struct _Unwind_Exception *exception_object);
 #else
 extern _Unwind_Reason_Code
     _Unwind_RaiseException(struct _Unwind_Exception *exception_object);
 extern void _Unwind_Resume(struct _Unwind_Exception *exception_object);
 #endif
 extern void _Unwind_DeleteException(struct _Unwind_Exception *exception_object);
 extern uintptr_t _Unwind_GetGR(struct _Unwind_Context *context, int index);
 extern void _Unwind_SetGR(struct _Unwind_Context *context, int index,
                           uintptr_t new_value);
 extern uintptr_t _Unwind_GetIP(struct _Unwind_Context *context);
 extern void _Unwind_SetIP(struct _Unwind_Context *, uintptr_t new_value);
 extern uintptr_t _Unwind_GetRegionStart(struct _Unwind_Context *context);
 extern uintptr_t
     _Unwind_GetLanguageSpecificData(struct _Unwind_Context *context);
-#if __arm__
+#if LIBCXXABI_SJLJ
 extern _Unwind_Reason_Code
     _Unwind_SjLj_ForcedUnwind(struct _Unwind_Exception *exception_object,
                               _Unwind_Stop_Fn stop, void *stop_parameter);
 #else
 extern _Unwind_Reason_Code
     _Unwind_ForcedUnwind(struct _Unwind_Exception *exception_object,
                          _Unwind_Stop_Fn stop, void *stop_parameter);
 #endif
 
-#if __arm__
+#if LIBCXXABI_SJLJ
 typedef struct _Unwind_FunctionContext *_Unwind_FunctionContext_t;
 extern void _Unwind_SjLj_Register(_Unwind_FunctionContext_t fc);
 extern void _Unwind_SjLj_Unregister(_Unwind_FunctionContext_t fc);
 #endif
 
 //
 // The following are semi-suppoted extensions to the C++ ABI
 //
 
 //
 //  called by __cxa_rethrow().
 //
-#if __arm__
+#if LIBCXXABI_SJLJ
 extern _Unwind_Reason_Code
     _Unwind_SjLj_Resume_or_Rethrow(struct _Unwind_Exception *exception_object);
 #else
 extern _Unwind_Reason_Code
     _Unwind_Resume_or_Rethrow(struct _Unwind_Exception *exception_object);
 #endif
 
 // _Unwind_Backtrace() is a gcc extension that walks the stack and calls the

src/cxa_exception.cpp

__cxa_throw(void* thrown_object, std::type_info* tinfo, void (*dest)(void*))
     exception_header->terminateHandler  = std::get_terminate();
     exception_header->exceptionType = tinfo;
     exception_header->exceptionDestructor = dest;
     setExceptionClass(&exception_header->unwindHeader);
     exception_header->referenceCount = 1;  // This is a newly allocated exception, no need for thread safety.
     globals->uncaughtExceptions += 1;   // Not atomically, since globals are thread-local
 
     exception_header->unwindHeader.exception_cleanup = exception_cleanup_func;
-#if __arm__
+#if LIBCXXABI_SJLJ
     _Unwind_SjLj_RaiseException(&exception_header->unwindHeader);
 #else
     _Unwind_RaiseException(&exception_header->unwindHeader);
 #endif
     //  This only happens when there is no handler, or some unexpected unwinding
     //     error happens.
     failed_throw(exception_header);
 }
__cxa_rethrow()
     else  // this is a foreign exception
     {
         // The only way to communicate to __cxa_end_catch that we've rethrown
         //   a foreign exception, so don't delete us, is to pop the stack here
         //   which must be empty afterwards.  Then __cxa_end_catch will do
         //   nothing
         globals->caughtExceptions = 0;
     }
-#if __arm__
+#if LIBCXXABI_SJLJ
     _Unwind_SjLj_RaiseException(&exception_header->unwindHeader);
 #else
     _Unwind_RaiseException(&exception_header->unwindHeader);
 #endif
 
     //  If we get here, some kind of unwinding error has occurred.
     //  There is some weird code generation bug happening with 
     //     Apple clang version 4.0 (tags/Apple/clang-418.0.2) (based on LLVM 3.1svn)
if ( thrown_object != NULL )
         dep_exception_header->primaryException = thrown_object;
         __cxa_increment_exception_refcount(thrown_object);
         dep_exception_header->exceptionType = exception_header->exceptionType;
         dep_exception_header->unexpectedHandler = std::get_unexpected();
         dep_exception_header->terminateHandler = std::get_terminate();
         setDependentExceptionClass(&dep_exception_header->unwindHeader);
         __cxa_get_globals()->uncaughtExceptions += 1;
         dep_exception_header->unwindHeader.exception_cleanup = dependent_exception_cleanup;
-#if __arm__
+#if LIBCXXABI_SJLJ
         _Unwind_SjLj_RaiseException(&dep_exception_header->unwindHeader);
 #else
         _Unwind_RaiseException(&dep_exception_header->unwindHeader);
 #endif
         // Some sort of unwinding error.  Note that terminate is a handler.
         __cxa_begin_catch(&dep_exception_header->unwindHeader);
     }
     // If we return client will call terminate()