[RFA v2 13/13] Remove verbose code from backtrace command

Tom Tromey
2017-08-14T03:41:06Z

In https://sourceware.org/ml/gdb-patches/2017-06/msg00741.html,
Pedro asks:

> Doesn't the "info verbose on" bit affect frame filters too?

The answer is that yes, it could. However, it's not completely
effective, because the C code can't guess how many frames might need
to be unwound to satisfy the request -- a frame filter will request as
many frames as it needs.

Also, I tried removing this code from backtrace, and I think the
result is better without it. In particular, now the expansion line
occurs just before the frame that caused the expansion, like:

(gdb) bt no-filters
#0 0x00007ffff576cecd in poll () from /lib64/libc.so.6
Reading in symbols for ../../binutils-gdb/gdb/event-loop.c...done.
#1 0x00000000007ecc33 in gdb_wait_for_event (block=1)
at ../../binutils-gdb/gdb/event-loop.c:772
#2 0x00000000007ec006 in gdb_do_one_event ()
at ../../binutils-gdb/gdb/event-loop.c:347
#3 0x00000000007ec03e in start_event_loop ()
at ../../binutils-gdb/gdb/event-loop.c:371
Reading in symbols for ../../binutils-gdb/gdb/main.c...done.
#4 0x000000000086693d in captured_command_loop (
Reading in symbols for ../../binutils-gdb/gdb/exceptions.c...done.
data=0x0) at ../../binutils-gdb/gdb/main.c:325

So, I am proposing this patch to simply remove this code.

ChangeLog
2017-08-13 Tom Tromey <tom@tromey.com>

* stack.c (backtrace_command_1): Remove verbose code.
---
gdb/ChangeLog | 4 ++++
gdb/stack.c | 18 ------------------
2 files changed, 4 insertions(+), 18 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 0ed62ce..f621822 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,9 @@
2017-08-13 Tom Tromey <tom@tromey.com>

+ * stack.c (backtrace_command_1): Remove verbose code.
+
+2017-08-13 Tom Tromey <tom@tromey.com>
+
* python/py-framefilter.c (py_print_type): Don't catch
exceptions. Return void.
(py_print_value): Likewise.
diff --git a/gdb/stack.c b/gdb/stack.c
index 20cdd97..8ba2239 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -1798,24 +1798,6 @@ backtrace_command_1 (char *count_exp, int flags, int no_filters,
count = -1;
}

- if (info_verbose)
- {
- /* Read in symbols for all of the frames. Need to do this in a
- separate pass so that "Reading in symbols for xxx" messages
- don't screw up the appearance of the backtrace. Also if
- people have strong opinions against reading symbols for
- backtrace this may have to be an option. */
- i = count;
- for (fi = trailing; fi != NULL && i--; fi = get_prev_frame (fi))
- {
- CORE_ADDR pc;
-
- QUIT;
- pc = get_frame_address_in_block (fi);
- expand_symtab_containing_pc (pc, find_pc_mapped_section (pc));
- }
- }
-
for (i = 0, fi = trailing; fi && count--; i++, fi = get_prev_frame (fi))
{
QUIT;
--
2.9.4