unwind: Fix libc++abi and libgcc build.

loganchien · loganchien · commit ff8fbf9f9054 · 2015-07-24T00:16:48.000Z
To build libc++abi without libunwind, we should make sure that all
function calls to _Unwind_{Get,Set}{GR,IP}() are inlined as function
calls to _Unwind_VRS_{Get,Set}().  Otherwise, libc++abi.so will fail to
link since libgcc does not provide these symbol at all.

This commit fixes the problem by providing both the inlined version and
exported version.

llvm-svn: 243073
diff --git a/libunwind/include/unwind.h b/libunwind/include/unwind.h
@@ -204,12 +204,55 @@ _Unwind_VRS_Pop(_Unwind_Context *context, _Unwind_VRS_RegClass regclass,
                 _Unwind_VRS_DataRepresentation representation);
 #endif
 
+#if !_LIBUNWIND_ARM_EHABI
+
 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);
 
+#else  // _LIBUNWIND_ARM_EHABI
+
+#if defined(_LIBUNWIND_UNWIND_LEVEL1_EXTERNAL_LINKAGE)
+#define _LIBUNWIND_EXPORT_UNWIND_LEVEL1 extern
+#else
+#define _LIBUNWIND_EXPORT_UNWIND_LEVEL1 static __inline__
+#endif
+
+// These are de facto helper functions for ARM, which delegate the function
+// calls to _Unwind_VRS_Get/Set().  These are not a part of ARM EHABI
+// specification, thus these function MUST be inlined.  Please don't replace
+// these with the "extern" function declaration; otherwise, the program
+// including this <unwind.h> header won't be ABI compatible and will result in
+// link error when we are linking the program with libgcc.
+
+_LIBUNWIND_EXPORT_UNWIND_LEVEL1
+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;
+}
+
+_LIBUNWIND_EXPORT_UNWIND_LEVEL1
+void _Unwind_SetGR(struct _Unwind_Context *context, int index,
+                   uintptr_t value) {
+  _Unwind_VRS_Set(context, _UVRSC_CORE, (uint32_t)index, _UVRSD_UINT32, &value);
+}
+
+_LIBUNWIND_EXPORT_UNWIND_LEVEL1
+uintptr_t _Unwind_GetIP(struct _Unwind_Context *context) {
+  // remove the thumb-bit before returning
+  return _Unwind_GetGR(context, 15) & (~(uintptr_t)0x1);
+}
+
+_LIBUNWIND_EXPORT_UNWIND_LEVEL1
+void _Unwind_SetIP(struct _Unwind_Context *context, uintptr_t value) {
+  uintptr_t thumb_bit = _Unwind_GetGR(context, 15) & ((uintptr_t)0x1);
+  _Unwind_SetGR(context, 15, value | thumb_bit);
+}
+#endif  // _LIBUNWIND_ARM_EHABI
+
 extern uintptr_t _Unwind_GetRegionStart(struct _Unwind_Context *context);
 extern uintptr_t
     _Unwind_GetLanguageSpecificData(struct _Unwind_Context *context);
diff --git a/libunwind/src/UnwindLevel1.c b/libunwind/src/UnwindLevel1.c
@@ -12,6 +12,13 @@
 //
 //===----------------------------------------------------------------------===//
 
+// ARM EHABI does not specify _Unwind_{Get,Set}{GR,IP}().  Thus, we are
+// defining inline functions to delegate the function calls to
+// _Unwind_VRS_{Get,Set}().  However, some applications might declare the
+// function protetype directly (instead of including <unwind.h>), thus we need
+// to export these functions from libunwind.so as well.
+#define _LIBUNWIND_UNWIND_LEVEL1_EXTERNAL_LINKAGE 1
+
 #include <inttypes.h>
 #include <stdint.h>
 #include <stdbool.h>
@@ -496,39 +503,4 @@ _LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *context,
   unw_set_reg(cursor, UNW_REG_IP, value);
 }
 
-#else
-
-_LIBUNWIND_EXPORT 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);
-  _LIBUNWIND_TRACE_API("_Unwind_GetGR(context=%p, reg=%d) => 0x%" PRIx64 "\n",
-                       (void *)context, index, (uint64_t)value);
-  return value;
-}
-
-_LIBUNWIND_EXPORT void _Unwind_SetGR(struct _Unwind_Context *context, int index,
-                                     uintptr_t value) {
-  _LIBUNWIND_TRACE_API("_Unwind_SetGR(context=%p, reg=%d, value=0x%0"PRIx64")\n",
-                       (void *)context, index, (uint64_t)value);
-  _Unwind_VRS_Set(context, _UVRSC_CORE, (uint32_t)index, _UVRSD_UINT32, &value);
-}
-
-_LIBUNWIND_EXPORT uintptr_t _Unwind_GetIP(struct _Unwind_Context *context) {
-  // remove the thumb-bit before returning
-  uintptr_t value = _Unwind_GetGR(context, 15) & (~(uintptr_t)0x1);
-  _LIBUNWIND_TRACE_API("_Unwind_GetIP(context=%p) => 0x%" PRIx64 "\n",
-                       (void *)context, (uint64_t)value);
-  return value;
-}
-
-_LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *context,
-                                     uintptr_t value) {
-  _LIBUNWIND_TRACE_API("_Unwind_SetIP(context=%p, value=0x%0" PRIx64 ")\n",
-                       (void *)context, (uint64_t)value);
-  uintptr_t thumb_bit = _Unwind_GetGR(context, 15) & ((uintptr_t)0x1);
-  _Unwind_SetGR(context, 15, value | thumb_bit);
-}
-
 #endif // !_LIBUNWIND_ARM_EHABI
-
