[Bug gdb/12938] New: RFE: Find the regression point in the code

[Bug gdb/12938] New: RFE: Find the regression point in the code

[jan.kratochvil at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12938

           Summary: RFE: Find the regression point in the code
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: gdb
        AssignedTo: unassigned@sourceware.org
        ReportedBy: jan.kratochvil@redhat.com


Diego Novillo has asked to find where the execution of two inferiors (with two
different executables) starts to differ - to find the exact regression point in
the code.

Currently I use reverse execution to iterate down throught the code where the
behavior still does / does not differ.

The problem with the automatic way may be to properly differentiate ignorable
vs. significant execution differences.

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[Bug gdb/12938] RFE: Find the regression point in the code

[pedro at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12938

Pedro Alves <pedro at codesourcery dot com> changed:

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                 CC|                            |pedro at codesourcery dot
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--- Comment #1 from Pedro Alves <pedro at codesourcery dot com> 2011-06-28 10:02:58 UTC ---
A while ago someone posted
<http://comments.gmane.org/gmane.comp.gdb.devel/27441>
showing an approach for this use case that builds on top of gdb, rather than
built in:

"(...) which was written to run two gdb's debugging a stage1 and
stage2 generation of a compiler and single step until a line number differs.
It is written in Python and uses pexpect"

>From tgdb-0.1.tar.gz's README.

"TwinGDB is a front end to GDB which runs two instances of gdb on two
executables and will automatically single step them until a deviation
(seen by line number) occurs.  Typically this is useful if you are
developing a program for a different archicture or if you are in
compiler development where a second generation build fails to behave
in exactly the same way as the first generation.  It can also be used
to explore when a particular command line option takes effect.  There
are probably more uses as well..

This program is in a pre alpha state, nevetheless, the author uses
it to debug GNU Modula-2.

As single stepping gdb is not exactly fast, the program can be
configured to skip functions, skip source files which reside in
particular directories, start stepping at a particular function and
finish at another etc."

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[Bug gdb/12938] RFE: Find the regression point in the code

[dje at google dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12938

dje at google dot com changed:

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                 CC|                            |dje at google dot com

--- Comment #2 from dje at google dot com 2011-09-20 22:13:25 UTC ---
Copied from 13207 for reference sake:
Such a script feels like more of a contrib-like patch, than part of gdb proper,
but it still feels like something gdb could/should provide.
When it works, it's a real timesaver, and the basic infrastructure shouldn't be
that hard to write in python (and if it is then we've found good places where
python needs to be extended).

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[Bug gdb/12938] RFE: Find the regression point in the code

[dje at google dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12938

--- Comment #3 from dje at google dot com 2011-09-20 22:15:12 UTC ---
*** Bug 13207 has been marked as a duplicate of this bug. ***

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[Bug gdb/12938] RFE: Find the regression point in the code

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12938

Tom Tromey <tromey at redhat dot com> changed:

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           Keywords|                            |archer
                 CC|                            |tromey at redhat dot com

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