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* [Bug breakpoints/29480] New: [gdb] watchpoint condition on specific value change @ 2022-08-12 11:42 vries at gcc dot gnu.org 2022-08-12 17:02 ` [Bug breakpoints/29480] " tromey at sourceware dot org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: vries at gcc dot gnu.org @ 2022-08-12 11:42 UTC (permalink / raw) To: gdb-prs https://sourceware.org/bugzilla/show_bug.cgi?id=29480 Bug ID: 29480 Summary: [gdb] watchpoint condition on specific value change Product: gdb Version: HEAD Status: NEW Severity: enhancement Priority: P2 Component: breakpoints Assignee: unassigned at sourceware dot org Reporter: vries at gcc dot gnu.org Target Milestone: --- Somebody asked on IRC: ... is it possible to setup a watchpoint that fires off when the value of a memory location changes from one specific value to another? ... I wrote this test example: ... $ cat test.c int v = 0; int main (void) { v = 1; v = 2; v = 3; v = 2; return 0; } $ gcc -g test.c ... and decided I wanted to set a watchpoint on the change from 3 to 2. I suppose it's possible to do this in python somehow, but I decided to try something more simple. I wrote this patch that introduces two new convenience variables: ... diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c index 37f70a77721..90ec605aeeb 100644 --- a/gdb/breakpoint.c +++ b/gdb/breakpoint.c @@ -5062,7 +5062,10 @@ watchpoint_check (bpstat *bs) new_val))) { bs->old_val = b->val; + set_internalvar (lookup_internalvar ("_wp_old_val"), + bs->old_val.get ()); b->val = release_value (new_val); + set_internalvar (lookup_internalvar ("_wp_val"), b->val.get ()); b->val_valid = true; if (new_val != NULL) value_free_to_mark (mark); ... and managed to do: ... $ gdb -q -batch a.out -ex "watch v" -ex "cond 1 \$_wp_old_val == 3 && \$_wp_val == 2" -ex run Hardware watchpoint 1: v Hardware watchpoint 1: v Old value = 3 New value = 2 main () at test.c:12 12 return 0; ... -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug breakpoints/29480] [gdb] watchpoint condition on specific value change 2022-08-12 11:42 [Bug breakpoints/29480] New: [gdb] watchpoint condition on specific value change vries at gcc dot gnu.org @ 2022-08-12 17:02 ` tromey at sourceware dot org 2022-08-12 17:35 ` vries at gcc dot gnu.org 2022-09-30 9:16 ` vries at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: tromey at sourceware dot org @ 2022-08-12 17:02 UTC (permalink / raw) To: gdb-prs https://sourceware.org/bugzilla/show_bug.cgi?id=29480 Tom Tromey <tromey at sourceware dot org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |tromey at sourceware dot org --- Comment #1 from Tom Tromey <tromey at sourceware dot org> --- There's another bug somewhere, I think, about wanting access to the previous value. Seems like a good idea. -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug breakpoints/29480] [gdb] watchpoint condition on specific value change 2022-08-12 11:42 [Bug breakpoints/29480] New: [gdb] watchpoint condition on specific value change vries at gcc dot gnu.org 2022-08-12 17:02 ` [Bug breakpoints/29480] " tromey at sourceware dot org @ 2022-08-12 17:35 ` vries at gcc dot gnu.org 2022-09-30 9:16 ` vries at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: vries at gcc dot gnu.org @ 2022-08-12 17:35 UTC (permalink / raw) To: gdb-prs https://sourceware.org/bugzilla/show_bug.cgi?id=29480 --- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> --- (In reply to Tom Tromey from comment #1) > There's another bug somewhere, I think, about wanting > access to the previous value. > Seems like a good idea. Maybe this ( https://sourceware.org/bugzilla/show_bug.cgi?id=7349 ) one ? -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug breakpoints/29480] [gdb] watchpoint condition on specific value change 2022-08-12 11:42 [Bug breakpoints/29480] New: [gdb] watchpoint condition on specific value change vries at gcc dot gnu.org 2022-08-12 17:02 ` [Bug breakpoints/29480] " tromey at sourceware dot org 2022-08-12 17:35 ` vries at gcc dot gnu.org @ 2022-09-30 9:16 ` vries at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: vries at gcc dot gnu.org @ 2022-09-30 9:16 UTC (permalink / raw) To: gdb-prs https://sourceware.org/bugzilla/show_bug.cgi?id=29480 Tom de Vries <vries at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |UNCONFIRMED Ever confirmed|1 |0 --- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> --- https://sourceware.org/pipermail/gdb-patches/2022-September/192213.html -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-09-30 9:17 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-08-12 11:42 [Bug breakpoints/29480] New: [gdb] watchpoint condition on specific value change vries at gcc dot gnu.org 2022-08-12 17:02 ` [Bug breakpoints/29480] " tromey at sourceware dot org 2022-08-12 17:35 ` vries at gcc dot gnu.org 2022-09-30 9:16 ` vries at gcc dot gnu.org
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