Remove _Unwind_{Get,Set}{GR,IP} from ARM EHABI build.

[logan]

Summary

I found that declaring _Unwind_{Get,Set}{GR,IP} as the external
functions will break the build with libgcc, which does not define
these functions in their libraries.

Besides, IMO, since these are not part of the ARM EHABI specification
it will be better to avoid introducing ABI backward incompatible
changes.

This commit partially reverts r219629.

Please have a look. Thanks.

(p.s. This is the 1/6 patch to fix the backtrace_test and libgcc support.)

[rengolin]

LGTM, Thanks!

--renato

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Fix the conditional compilation guard.

It seems that I forgot to delete this when I was rebasing.

[logan]

Thanks. Committed with rL226818.

include/unwind.h

_Unwind_VRS_Set(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
                 void *valuep);
 
 extern _Unwind_VRS_Result
 _Unwind_VRS_Pop(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
                 uint32_t discriminator,
                 _Unwind_VRS_DataRepresentation representation);
 #endif
 
+#if LIBCXXABI_ARM_EHABI
+static inline uintptr_t _Unwind_GetGR(struct _Unwind_Context* context,
+                                      int index) {
+  uintptr_t value = 0;
+  _Unwind_VRS_Get(context, _UVRSC_CORE, (uint32_t)index, _UVRSD_UINT32, &value);
+  return value;
+}
+
+static inline void _Unwind_SetGR(struct _Unwind_Context* context, int index,
+                                 uintptr_t new_value) {
+  _Unwind_VRS_Set(context, _UVRSC_CORE, (uint32_t)index,
+                  _UVRSD_UINT32, &new_value);
+}
+
+static inline uintptr_t _Unwind_GetIP(struct _Unwind_Context* context) {
+  // remove the thumb-bit before returning
+  return (_Unwind_GetGR(context, 15) & (~(uintptr_t)0x1));
+}
+
+static inline void _Unwind_SetIP(struct _Unwind_Context* context,
+                                 uintptr_t new_value) {
+  uintptr_t thumb_bit = _Unwind_GetGR(context, 15) & ((uintptr_t)0x1);
+  _Unwind_SetGR(context, 15, new_value | thumb_bit);
+}
+#else
 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);
+#endif
 
 extern uintptr_t _Unwind_GetRegionStart(struct _Unwind_Context *context);
 extern uintptr_t
     _Unwind_GetLanguageSpecificData(struct _Unwind_Context *context);
 #if __USING_SJLJ_EXCEPTIONS__
 extern _Unwind_Reason_Code
     _Unwind_SjLj_ForcedUnwind(_Unwind_Exception *exception_object,
                               _Unwind_Stop_Fn stop, void *stop_parameter);

src/Unwind/Unwind-EHABI.cpp

 // Generates mask discriminator for _Unwind_VRS_Pop, e.g. for _UVRSC_VFP /
 // _UVRSD_DOUBLE.
 uint32_t RegisterRange(uint8_t start, uint8_t count_minus_one) {
   return ((uint32_t)start << 16) | ((uint32_t)count_minus_one + 1);
 }
 
 } // end anonymous namespace
 
-uintptr_t _Unwind_GetGR(struct _Unwind_Context* context, int index) {
-  uintptr_t value = 0;
-  _Unwind_VRS_Get(context, _UVRSC_CORE, (uint32_t)index, _UVRSD_UINT32, &value);
-  return value;
-}
-
-void _Unwind_SetGR(struct _Unwind_Context* context, int index, uintptr_t
-    new_value) {
-  _Unwind_VRS_Set(context, _UVRSC_CORE, (uint32_t)index,
-                  _UVRSD_UINT32, &new_value);
-}
-
-uintptr_t _Unwind_GetIP(struct _Unwind_Context* context) {
-  // remove the thumb-bit before returning
-  return (_Unwind_GetGR(context, 15) & (~(uintptr_t)0x1));
-}
-
-void _Unwind_SetIP(struct _Unwind_Context* context, uintptr_t new_value) {
-  uintptr_t thumb_bit = _Unwind_GetGR(context, 15) & ((uintptr_t)0x1);
-  _Unwind_SetGR(context, 15, new_value | thumb_bit);
-}
-
 /**
  * Decodes an EHT entry.
  *
  * @param data Pointer to EHT.
  * @param[out] off Offset from return value (in bytes) to begin interpretation.
  * @param[out] len Number of bytes in unwind code.
  * @return Pointer to beginning of unwind code.
  */