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* frame.c (get_prev_frame_1): Work around GCC bug. 

* frame.h: Add comment about GCC bug.
This commit is contained in:
Mark Kettenis 2004-05-07 23:19:14 +00:00
parent 2b4855ab6b
commit 756e95f198
3 changed files with 26 additions and 6 deletions
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5
gdb/ChangeLog
View File

@ -1,3 +1,8 @@
2004-05-08 Mark Kettenis <kettenis@gnu.org>
* frame.c (get_prev_frame_1): Work around GCC bug.
* frame.h: Add comment about GCC bug.
2004-05-07 Andrew Cagney <cagney@redhat.com> 2004-05-07 Andrew Cagney <cagney@redhat.com>
* observer.c: Include "commands.h" and "gdbcmd.h". * observer.c: Include "commands.h" and "gdbcmd.h".

10
gdb/frame.c
View File

@ -1609,6 +1609,7 @@ static struct frame_info *
get_prev_frame_1 (struct frame_info *this_frame) get_prev_frame_1 (struct frame_info *this_frame)
{ {
struct frame_info *prev_frame; struct frame_info *prev_frame;
struct frame_id this_id;
gdb_assert (this_frame != NULL); gdb_assert (this_frame != NULL);
@ -1646,7 +1647,8 @@ get_prev_frame_1 (struct frame_info *this_frame)
/* Check that this frame's ID was valid. If it wasn't, don't try to /* Check that this frame's ID was valid. If it wasn't, don't try to
unwind to the prev frame. Be careful to not apply this test to unwind to the prev frame. Be careful to not apply this test to
the sentinel frame. */ the sentinel frame. */
if (this_frame->level >= 0 && !frame_id_p (get_frame_id (this_frame))) this_id = get_frame_id (this_frame);
if (this_frame->level >= 0 && !frame_id_p (this_id))
{ {
if (frame_debug) if (frame_debug)
{ {
@ -1663,16 +1665,14 @@ get_prev_frame_1 (struct frame_info *this_frame)
go backwards) and sentinel frames (the test is meaningless). */ go backwards) and sentinel frames (the test is meaningless). */
if (this_frame->next->level >= 0 if (this_frame->next->level >= 0
&& this_frame->next->type != SIGTRAMP_FRAME && this_frame->next->type != SIGTRAMP_FRAME
&& frame_id_inner (get_frame_id (this_frame), && frame_id_inner (this_id, get_frame_id (this_frame->next)))
get_frame_id (this_frame->next)))
error ("Previous frame inner to this frame (corrupt stack?)"); error ("Previous frame inner to this frame (corrupt stack?)");
/* Check that this and the next frame are not identical. If they /* Check that this and the next frame are not identical. If they
are, there is most likely a stack cycle. As with the inner-than are, there is most likely a stack cycle. As with the inner-than
test above, avoid comparing the inner-most and sentinel frames. */ test above, avoid comparing the inner-most and sentinel frames. */
if (this_frame->level > 0 if (this_frame->level > 0
&& frame_id_eq (get_frame_id (this_frame), && frame_id_eq (this_id, get_frame_id (this_frame->next)))
get_frame_id (this_frame->next)))
error ("Previous frame identical to this frame (corrupt stack?)"); error ("Previous frame identical to this frame (corrupt stack?)");
/* Allocate the new frame but do not wire it in to the frame chain. /* Allocate the new frame but do not wire it in to the frame chain.

17
gdb/frame.h
View File

@ -310,7 +310,22 @@ extern CORE_ADDR get_frame_base (struct frame_info *);
/* Return the per-frame unique identifer. Can be used to relocate a /* Return the per-frame unique identifer. Can be used to relocate a
frame after a frame cache flush (and other similar operations). If frame after a frame cache flush (and other similar operations). If
FI is NULL, return the null_frame_id. */ FI is NULL, return the null_frame_id.
NOTE: kettenis/20040508: These functions return a structure. On
platforms where structures are returned in static storage (vax,
m68k), this may trigger compiler bugs in code like:
if (frame_id_eq (get_frame_id (l), get_frame_id (r)))
where the return value from the first get_frame_id (l) gets
overwritten by the second get_frame_id (r). Please avoid writing
code like this. Use code like:
struct frame_id id = get_frame_id (l);
if (frame_id_eq (id, get_frame_id (r)))
instead, since that avoids the bug. */
extern struct frame_id get_frame_id (struct frame_info *fi); extern struct frame_id get_frame_id (struct frame_info *fi);
extern struct frame_id frame_unwind_id (struct frame_info *next_frame); extern struct frame_id frame_unwind_id (struct frame_info *next_frame);