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* [Bug gdb/16481] New: Python finish breakpoint does not work with a mix of inlined and tailcalled functions
@ 2014-01-21 22:51 simon.marchi at polymtl dot ca
2014-01-21 22:58 ` [Bug python/16481] " simon.marchi at polymtl dot ca
2023-12-15 19:59 ` ssbssa at sourceware dot org
0 siblings, 2 replies; 3+ messages in thread
From: simon.marchi at polymtl dot ca @ 2014-01-21 22:51 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=16481
Bug ID: 16481
Summary: Python finish breakpoint does not work with a mix of
inlined and tailcalled functions
Product: gdb
Version: HEAD
Status: NEW
Severity: normal
Priority: P2
Component: gdb
Assignee: unassigned at sourceware dot org
Reporter: simon.marchi at polymtl dot ca
This may seem a little far fetched, but I hit this while trying to track memory
allocations with a python script. I put a Python breakpoint on __libc_malloc,
which in turn sets a finish breakpoint so that I can get the pointer to the
allocated region. I noticed that some times, the finish breakpoint is never
hit.
I put up a very simple test case here:
https://gist.github.com/simark/8548964
Compile with
$ gcc -g test.c -O3
Run with
$ gdb -x finish.py a.out
As the name describe, hopefully_inlined is inlined, hopefully_tailcalled is
tailcalled (did I just invent a verb?).
The python script sets a breakpoint on the hopefully_notinlined function, which
instanciantes a finish breakpoint. On exit of the function, we should see "I am
here", but we don't.
I diagnosed the problem, and something wrong seems to happen here:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=gdb/breakpoint.c;h=c8e7e8842e2ed418d78b23c466018c88bb5e2aae;hb=HEAD#l5172
>From what I understand, for kinds of breakpoints where it makes sens, GDB
checks that the current stack frame is the same as when the breakpoint was set.
For the breakpoint to cause a stop, they have to match. The comparison in this
case returns false. One of the frames has its artifical_depth to zero while the
other has it to one. I am not sure which one is right, but I think that they
should be equal...
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* [Bug python/16481] Python finish breakpoint does not work with a mix of inlined and tailcalled functions
2014-01-21 22:51 [Bug gdb/16481] New: Python finish breakpoint does not work with a mix of inlined and tailcalled functions simon.marchi at polymtl dot ca
@ 2014-01-21 22:58 ` simon.marchi at polymtl dot ca
2023-12-15 19:59 ` ssbssa at sourceware dot org
1 sibling, 0 replies; 3+ messages in thread
From: simon.marchi at polymtl dot ca @ 2014-01-21 22:58 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=16481
Simon Marchi <simon.marchi at polymtl dot ca> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|gdb |python
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* [Bug python/16481] Python finish breakpoint does not work with a mix of inlined and tailcalled functions
2014-01-21 22:51 [Bug gdb/16481] New: Python finish breakpoint does not work with a mix of inlined and tailcalled functions simon.marchi at polymtl dot ca
2014-01-21 22:58 ` [Bug python/16481] " simon.marchi at polymtl dot ca
@ 2023-12-15 19:59 ` ssbssa at sourceware dot org
1 sibling, 0 replies; 3+ messages in thread
From: ssbssa at sourceware dot org @ 2023-12-15 19:59 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=16481
Hannes Domani <ssbssa at sourceware dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |15.1
CC| |ssbssa at sourceware dot org
Resolution|--- |FIXED
Status|NEW |RESOLVED
--- Comment #1 from Hannes Domani <ssbssa at sourceware dot org> ---
I didn't know about this bug report, but I fixed this a few days ago with this
commit:
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=80ffe7226459e3edf840d0c23462d93cb560d2de
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2014-01-21 22:51 [Bug gdb/16481] New: Python finish breakpoint does not work with a mix of inlined and tailcalled functions simon.marchi at polymtl dot ca
2014-01-21 22:58 ` [Bug python/16481] " simon.marchi at polymtl dot ca
2023-12-15 19:59 ` ssbssa at sourceware dot org
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