From 756e95f19845d6194524bd9f4c37851f3f7b8de5 Mon Sep 17 00:00:00 2001 From: Mark Kettenis Date: Fri, 7 May 2004 23:19:14 +0000 Subject: [PATCH] * frame.c (get_prev_frame_1): Work around GCC bug. * frame.h: Add comment about GCC bug. --- gdb/ChangeLog | 5 +++++ gdb/frame.c | 10 +++++----- gdb/frame.h | 17 ++++++++++++++++- 3 files changed, 26 insertions(+), 6 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index d7d33e6aba8..8fb8c981aa1 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2004-05-08 Mark Kettenis + + * frame.c (get_prev_frame_1): Work around GCC bug. + * frame.h: Add comment about GCC bug. + 2004-05-07 Andrew Cagney * observer.c: Include "commands.h" and "gdbcmd.h". diff --git a/gdb/frame.c b/gdb/frame.c index 8fb03442202..eba8605d63e 100644 --- a/gdb/frame.c +++ b/gdb/frame.c @@ -1609,6 +1609,7 @@ static struct frame_info * get_prev_frame_1 (struct frame_info *this_frame) { struct frame_info *prev_frame; + struct frame_id this_id; 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 unwind to the prev frame. Be careful to not apply this test to 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) { @@ -1663,16 +1665,14 @@ get_prev_frame_1 (struct frame_info *this_frame) go backwards) and sentinel frames (the test is meaningless). */ if (this_frame->next->level >= 0 && this_frame->next->type != SIGTRAMP_FRAME - && frame_id_inner (get_frame_id (this_frame), - get_frame_id (this_frame->next))) + && frame_id_inner (this_id, get_frame_id (this_frame->next))) error ("Previous frame inner to this frame (corrupt stack?)"); /* 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 test above, avoid comparing the inner-most and sentinel frames. */ if (this_frame->level > 0 - && frame_id_eq (get_frame_id (this_frame), - get_frame_id (this_frame->next))) + && frame_id_eq (this_id, get_frame_id (this_frame->next))) error ("Previous frame identical to this frame (corrupt stack?)"); /* Allocate the new frame but do not wire it in to the frame chain. diff --git a/gdb/frame.h b/gdb/frame.h index 2ab8b8edf6b..55d357cf14d 100644 --- a/gdb/frame.h +++ b/gdb/frame.h @@ -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 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 frame_unwind_id (struct frame_info *next_frame); -- 2.30.2