+#if USE_KEYMGR
+
+namespace {
+
+// LibgccObject - This is the structure defined in libgcc. There is no #include
+// provided for this structure, so we also define it here. libgcc calls it
+// "struct object". The structure is undocumented in libgcc.
+struct LibgccObject {
+ void *unused1;
+ void *unused2;
+ void *unused3;
+
+ /// frame - Pointer to the exception table.
+ void *frame;
+
+ /// encoding - The encoding of the object?
+ union {
+ struct {
+ unsigned long sorted : 1;
+ unsigned long from_array : 1;
+ unsigned long mixed_encoding : 1;
+ unsigned long encoding : 8;
+ unsigned long count : 21;
+ } b;
+ size_t i;
+ } encoding;
+
+ /// fde_end - libgcc defines this field only if some macro is defined. We
+ /// include this field even if it may not there, to make libgcc happy.
+ char *fde_end;
+
+ /// next - At least we know it's a chained list!
+ struct LibgccObject *next;
+};
+
+// "kemgr" stuff. Apparently, all frame tables are stored there.
+extern "C" void _keymgr_set_and_unlock_processwide_ptr(int, void *);
+extern "C" void *_keymgr_get_and_lock_processwide_ptr(int);
+#define KEYMGR_GCC3_DW2_OBJ_LIST 302 /* Dwarf2 object list */
+
+/// LibgccObjectInfo - libgcc defines this struct as km_object_info. It
+/// probably contains all dwarf tables that are loaded.
+struct LibgccObjectInfo {
+
+ /// seenObjects - LibgccObjects already parsed by the unwinding runtime.
+ ///
+ struct LibgccObject* seenObjects;
+
+ /// unseenObjects - LibgccObjects not parsed yet by the unwinding runtime.
+ ///
+ struct LibgccObject* unseenObjects;
+
+ unsigned unused[2];
+};
+
+/// darwin_register_frame - Since __register_frame does not work with darwin's
+/// libgcc,we provide our own function, which "tricks" libgcc by modifying the
+/// "Dwarf2 object list" key.
+void DarwinRegisterFrame(void* FrameBegin) {
+ // Get the key.
+ LibgccObjectInfo* LOI = (struct LibgccObjectInfo*)
+ _keymgr_get_and_lock_processwide_ptr(KEYMGR_GCC3_DW2_OBJ_LIST);
+ assert(LOI && "This should be preallocated by the runtime");
+
+ // Allocate a new LibgccObject to represent this frame. Deallocation of this
+ // object may be impossible: since darwin code in libgcc was written after
+ // the ability to dynamically register frames, things may crash if we
+ // deallocate it.
+ struct LibgccObject* ob = (struct LibgccObject*)
+ malloc(sizeof(struct LibgccObject));
+
+ // Do like libgcc for the values of the field.
+ ob->unused1 = (void *)-1;
+ ob->unused2 = 0;
+ ob->unused3 = 0;
+ ob->frame = FrameBegin;
+ ob->encoding.i = 0;
+ ob->encoding.b.encoding = llvm::dwarf::DW_EH_PE_omit;
+
+ // Put the info on both places, as libgcc uses the first or the the second
+ // field. Note that we rely on having two pointers here. If fde_end was a
+ // char, things would get complicated.
+ ob->fde_end = (char*)LOI->unseenObjects;
+ ob->next = LOI->unseenObjects;
+
+ // Update the key's unseenObjects list.
+ LOI->unseenObjects = ob;
+
+ // Finally update the "key". Apparently, libgcc requires it.
+ _keymgr_set_and_unlock_processwide_ptr(KEYMGR_GCC3_DW2_OBJ_LIST,
+ LOI);
+
+}
+
+}
+#endif // __APPLE__
+#endif // __GNUC__
+