From: H.J. Lu <hjl@gnu.org>
Date: Sat, 27 Feb 1999 21:54:23 +0000 (+0000)
Subject: frame.h: Update some comments.
X-Git-Tag: prereleases/egcs-1.1.2-prerelease-3~18
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3e4536775e57afd965db7a7b95b965e5afcaa85e;p=thirdparty%2Fgcc.git

frame.h: Update some comments.

        * frame.h: Update some comments.
        * crtstuff.c (TARGET_ATTRIBUTE_WEAK): Define.
        (__register_frame_info, __deregister_frame_info): Declare using
        TARGET_WEAK_ATTRIBUTE.
        (__do_global_dtors_aux): Check if __deregister_frame_info is
        zero before calling it.
        (__do_global_dtors): Likewise.
        (frame_dummy): Check if __register_frame_info is zero before
        calling it.
        (__frame_dummy): Likewise.

Co-Authored-By: Jeffrey A Law <law@cygnus.com>

From-SVN: r25486
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e8cb1929738b..c2e7878ace0d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,17 @@
+Sat Feb 27 22:48:38 1999  H.J. Lu  (hjl@gnu.org)
+			  Jeffrey A Law  (law@cygnus.com)
+
+	* frame.h: Update some comments.
+	* crtstuff.c (TARGET_ATTRIBUTE_WEAK): Define.
+	(__register_frame_info, __deregister_frame_info): Declare using
+	TARGET_WEAK_ATTRIBUTE.
+	(__do_global_dtors_aux): Check if __deregister_frame_info is
+	zero before calling it.
+	(__do_global_dtors): Likewise.
+	(frame_dummy): Check if __register_frame_info is zero before
+	calling it.
+	(__frame_dummy): Likewise.
+	
 Sat Feb 27 19:47:39 1999  Marc Espie <espie@openbsd.org>
 
 	* config/t-openbsd (T_CFLAGS): Add -Dmkstemps=my_mkstemps.
diff --git a/gcc/crtstuff.c b/gcc/crtstuff.c
index 8e50ac740d71..a1b9ef8706e7 100644
--- a/gcc/crtstuff.c
+++ b/gcc/crtstuff.c
@@ -56,6 +56,45 @@ Boston, MA 02111-1307, USA.  */
 #include <stddef.h>
 #include "frame.h"
 
+/* This really belongs in gansidecl.h, but for the egcs-1.1.x branch, the
+   only code which uses weak attributes is in this file and this file does
+   not include gansidecl.h.  */
+#ifndef TARGET_ATTRIBUTE_WEAK
+# if SUPPORTS_WEAK
+#  define TARGET_ATTRIBUTE_WEAK       __attribute__ ((weak))
+# else
+#  define TARGET_ATTRIBUTE_WEAK
+# endif
+#endif
+
+/* We do not want to add the weak attribute to the declarations of these
+   routines in frame.h because that will cause the definition of these
+   symbols to be weak as well.
+
+   This exposes a core issue, how to handle creating weak references vs
+   how to create weak definitions.  Either we have to have the definition
+   of TARGET_WEAK_ATTRIBUTE be conditional in the shared header files or
+   have a second declaration if we want a function's references to be weak,
+   but not its definition.
+
+   Making TARGET_WEAK_ATTRIBUTE conditional seems like a good solution until
+   one thinks about scaling to larger problems -- ie, the condition under
+   which TARGET_WEAK_ATTRIBUTE is active will eventually get far too
+   complicated.
+
+   So, we take an approach similar to #pragma weak -- we have a second
+   declaration for functions that we want to have weak references.
+
+   Neither way is particularly good.  */
+   
+/* References to __register_frame_info and __deregister_frame_info should
+   be weak in this file if at all possible.  */
+extern void __register_frame_info (void *, struct object *)
+				  TARGET_ATTRIBUTE_WEAK;
+
+extern void *__deregister_frame_info (void *)
+				     TARGET_ATTRIBUTE_WEAK;
+
 /* Provide default definitions for the pseudo-ops used to switch to the
    .ctors and .dtors sections.
  
@@ -142,7 +181,8 @@ __do_global_dtors_aux ()
     }
 
 #ifdef EH_FRAME_SECTION_ASM_OP
-  __deregister_frame_info (__EH_FRAME_BEGIN__);
+  if (__deregister_frame_info)
+    __deregister_frame_info (__EH_FRAME_BEGIN__);
 #endif
   completed = 1;
 }
@@ -170,7 +210,8 @@ static void
 frame_dummy ()
 {
   static struct object object;
-  __register_frame_info (__EH_FRAME_BEGIN__, &object);
+  if (__register_frame_info)
+    __register_frame_info (__EH_FRAME_BEGIN__, &object);
 }
 
 static void __attribute__ ((__unused__))
@@ -254,7 +295,8 @@ __do_global_dtors ()
     (*p) ();
 
 #ifdef EH_FRAME_SECTION_ASM_OP
-  __deregister_frame_info (__EH_FRAME_BEGIN__);
+  if (__deregister_frame_info)
+    __deregister_frame_info (__EH_FRAME_BEGIN__);
 #endif
 }
 
@@ -266,7 +308,8 @@ void
 __frame_dummy ()
 {
   static struct object object;
-  __register_frame_info (__EH_FRAME_BEGIN__, &object);
+  if (__register_frame_info)
+    __register_frame_info (__EH_FRAME_BEGIN__, &object);
 }
 #endif
 #endif
diff --git a/gcc/frame.h b/gcc/frame.h
index 7493d92f80bd..9d0d693975b3 100644
--- a/gcc/frame.h
+++ b/gcc/frame.h
@@ -34,6 +34,11 @@ struct object {
   struct object *next;
 };
 
+/* Note the following routines are exported interfaces from libgcc; do not
+   change these interfaces.  Instead create new interfaces.  Also note
+   references to these functions may be made weak in files where they
+   are referenced.  */
+
 extern void __register_frame (void * );
 extern void __register_frame_table (void *);
 extern void __deregister_frame (void *);