* configure.in: Disable collect2 for nextstep. Instead use

        crtbegin/crtend.
        * configure: Rebuilt.
        * config/nextstep.h (STARTFILE_SPEC): Add crtbegin.
        (ENDFILE_SPEC): Define.
        (OBJECT_FORMAT_MACHO): Define.
        (EH_FRAME_SECTION_ASM_OP): Define.
        * crtstuff.c: Handle MACHO.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@22487 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 70 insertions, 0 deletions

diff --git a/gcc/crtstuff.c b/gcc/crtstuff.c
index 8e50ac740d7..ce2c9561e64 100644
--- a/gcc/crtstuff.c
+++ b/gcc/crtstuff.c
@@ -56,6 +56,8 @@ Boston, MA 02111-1307, USA.  */
 #include <stddef.h>
 #include "frame.h"
 
+#ifndef OBJECT_FORMAT_MACHO
+
 /* Provide default definitions for the pseudo-ops used to switch to the
    .ctors and .dtors sections.
  
@@ -458,3 +460,71 @@ STATIC ui32 __FRAME_END__[] __attribute__ ((__unused__)) = { 0 };
 #endif /* EH_FRAME_SECTION */
 
 #endif /* defined(CRT_END) */
+
+#else  /* OBJECT_FORMAT_MACHO */
+
+/* For Mach-O format executables, we assume that the system's runtime is
+   smart enough to handle constructors and destructors, but doesn't have
+   an init section (if it can't even handle constructors/destructors
+   you should be using INVOKE__main, not crtstuff). All we need to do
+   is install/deinstall the frame information for exceptions. We do this
+   by putting a constructor in crtbegin.o and a destructor in crtend.o.
+
+   crtend.o also puts in the terminating zero in the frame information
+   segment. */
+
+/* The crtstuff for other object formats use the symbol __EH_FRAME_BEGIN__
+   to figure out the start of the exception frame, but here we use
+   getsectbynamefromheader to find this value. Either method would work,
+   but this method avoids creating any global symbols, which seems
+   cleaner. */
+
+#include <mach-o/ldsyms.h>
+extern const struct section *
+  getsectbynamefromheader (const struct mach_header *,
+			   const char *, const char *);
+
+#ifdef CRT_BEGIN
+
+static void __reg_frame_ctor () __attribute__ ((constructor));
+
+static void
+__reg_frame_ctor ()
+{
+  static struct object object;
+  const struct section *eh_frame;
+
+  eh_frame = getsectbynamefromheader (&_mh_execute_header,
+				      "__TEXT", "__eh_frame");
+  __register_frame_info ((void *) eh_frame->addr, &object);
+}
+
+#endif /* CRT_BEGIN */
+
+#ifdef CRT_END
+
+static void __dereg_frame_dtor () __attribute__ ((destructor));
+
+static
+void __dereg_frame_dtor ()
+{
+  const struct section *eh_frame;
+
+  eh_frame = getsectbynamefromheader (&_mh_execute_header,
+				      "__TEXT", "__eh_frame");
+  __deregister_frame_info ((void *) eh_frame->addr);
+}
+
+/* Terminate the frame section with a final zero. */
+
+/* Force cc1 to switch to .data section.  */
+static void * force_to_data[0] __attribute__ ((__unused__)) = { };
+
+typedef unsigned int ui32 __attribute__ ((mode (SI)));
+asm (EH_FRAME_SECTION_ASM_OP);
+static ui32 __FRAME_END__[] __attribute__ ((__unused__)) = { 0 };
+
+#endif /* CRT_END */
+
+#endif /* OBJECT_FORMAT_MACHO */
+