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Re: frame_register_unwind(): "frame != NULL" assertion failure


Here's one possible "fix" for the assertion failure.  I've come to the
conclusion that the real culprit is get_next_frame(), but, unfortunately,
the rest of gdb is not yet ready for it to return the sentinel frame.
(See the comment in the patch for more info.)  So, until it is, I propose
that we use this hack...

	* frame.c (create_sentinel_frame): Make static.  Add forward
	declaration.
	(frame_register_unwind): Add hack for converting NULL frames
	into a sentinel frame.
I think, if there is going to be a hac, then it should be in read_next_frame_reg().

However, can you please first investigate modifying the start of mips_init_extra_frame_info() where it does:

proc_desc = get_next_frame (fci) ? .....

to, when get_next_frame(fci) is null, call:

find_proc_desc (get_frame_pc (fci), fci, 1);

that is the current, and not prev frame.

Andrew



Index: frame.c
===================================================================
RCS file: /cvs/src/src/gdb/frame.c,v
retrieving revision 1.66
diff -u -p -r1.66 frame.c
--- frame.c 2 Feb 2003 20:31:43 -0000 1.66
+++ frame.c 13 Feb 2003 23:20:22 -0000
@@ -39,6 +39,8 @@
#include "command.h"
#include "gdbcmd.h"
+static struct frame_info * create_sentinel_frame (struct regcache *regcache);
+
/* Flag to indicate whether backtraces should stop at main. */
static int backtrace_below_main;
@@ -180,6 +182,15 @@ frame_register_unwind (struct frame_info
gdb_assert (realnump != NULL);
/* gdb_assert (bufferp != NULL); */
+ /* Note: kevinb/2003-02-13: This is a hack. The problem is that
+ get_next_frame() can return NULL when it really ought to be
+ returning the sentinel frame. So, when we detect frame == NULL,
+ just use the sentinel frame instead. + FIXME: Remove this hack once get_next_frame() has been fixed
+ to never return NULL. */
+ if (frame == NULL)
+ frame = create_sentinel_frame (current_regcache);
+
/* NOTE: cagney/2002-11-27: A program trying to unwind a NULL frame
is broken. There is always a frame. If there, for some reason,
isn't, there is some pretty busted code as it should have
@@ -429,7 +440,7 @@ frame_map_regnum_to_name (int regnum)
/* Create a sentinel frame. */
-struct frame_info *
+static struct frame_info *
create_sentinel_frame (struct regcache *regcache)
{
struct frame_info *frame = FRAME_OBSTACK_ZALLOC (struct frame_info);




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