old-cross-binutils/gdb/testsuite/gdb.python/py-frame-inline.c

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/* This test is part of GDB, the GNU debugger.
Copyright 2011-2015 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
volatile int v = 42;
__attribute__((__always_inline__)) static inline int
f (void)
{
/* Provide first stub line so that GDB understand the PC is already inside
the inlined function and does not expect a step into it. */
v++;
v++; /* break-here */
return v;
}
__attribute__((__noinline__)) static int
g (void)
{
volatile int l = v;
return f ();
}
int
main (void)
{
Fix PR backtrace/15558 This PR is about an assertion failure in GDB that can be triggered by setting "backtrace limit" to a value that causes GDB to stop unwinding after an inline frame. In this case, an assertion in inline_frame_this_id will trigger: /* We need a valid frame ID, so we need to be based on a valid frame. (...). */ gdb_assert (frame_id_p (*this_id)); Looking at the function: static void inline_frame_this_id (struct frame_info *this_frame, void **this_cache, struct frame_id *this_id) { struct symbol *func; /* In order to have a stable frame ID for a given inline function, we must get the stack / special addresses from the underlying real frame's this_id method. So we must call get_prev_frame. Because we are inlined into some function, there must be previous frames, so this is safe - as long as we're careful not to create any cycles. */ *this_id = get_frame_id (get_prev_frame (this_frame)); we see we're computing the frame id for the inline frame. If this is an inline frame, which is a virtual frame constructed based on debug info, on top of a real stack frame, we should _always_ be able to find where the frame was inlined into, as that ultimately just means peeling off the virtual frames on top of the real stack frame. If there ultimately was no prev (real) stack frame, then we wouldn't have been able to construct the inline frame either, by design. That's what the assertion catches. So we have an inline frame, we should _always_ be able to compute its ID, even if that means bypassing the user backtrace limits to get at the real stack frame's info. The problem is that inline_frame_id calls get_prev_frame, and that takes user backtrace limits into account. Code that wants to bypass the limits calls get_prev_frame_1 instead. Note how get_prev_frame_1 already skips all checks for inline frames: /* If we are unwinding from an inline frame, all of the below tests were already performed when we unwound from the next non-inline frame. We must skip them, since we can not get THIS_FRAME's ID until we have unwound all the way down to the previous non-inline frame. */ if (get_frame_type (this_frame) == INLINE_FRAME) return get_prev_frame_if_no_cycle (this_frame); And note how the related frame_unwind_caller_id function also uses get_prev_frame_1: struct frame_id frame_unwind_caller_id (struct frame_info *next_frame) { struct frame_info *this_frame; /* Use get_prev_frame_1, and not get_prev_frame. The latter will truncate the frame chain, leading to this function unintentionally returning a null_frame_id (e.g., when a caller requests the frame ID of "main()"s caller. */ next_frame = skip_artificial_frames (next_frame); this_frame = get_prev_frame_1 (next_frame); if (this_frame) return get_frame_id (skip_artificial_frames (this_frame)); else return null_frame_id; } get_prev_frame_1 is currently static in frame.c. As a _1 suffix is not a good name for an extern function, I've renamed it. Tested on x86-64 Fedora 17. gdb/ 2014-04-18 Pedro alves <palves@redhat.com> Tom Tromey <tromey@redhat.com> PR backtrace/15558 * frame.c (get_prev_frame_1): Rename to ... (get_prev_frame_always): ... this, and make extern. Adjust. (skip_artificial_frames): Use get_prev_frame_always. (frame_unwind_caller_id, frame_pop, get_prev_frame) (get_frame_unwind_stop_reason): Adjust to rename. * frame.h (get_prev_frame_always): Declare. * inline-frame.c: Include frame.h. (inline_frame_this_id): Use get_prev_frame_always. gdb/testsuite/ 2014-04-18 Tom Tromey <palves@redhat.com> Pedro alves <tromey@redhat.com> PR backtrace/15558 * gdb.opt/inline-bt.exp: Test backtracing from an inline function with a backtrace limit. * gdb.python/py-frame-inline.exp: Test running to an inline function with a backtrace limit, and printing the newest frame. * gdb.python/py-frame-inline.c (main): Call f.
2014-04-18 09:15:21 +00:00
int x = g ();
x += f ();
return x;
}