[Bug c++/15519] New: GDB 7.6 is 94x slower than GDB 7.5.1 using a certain core file

[Bug c++/15519] New: GDB 7.6 is 94x slower than GDB 7.5.1 using a certain core file

[psmith at gnu dot org]

http://sourceware.org/bugzilla/show_bug.cgi?id=15519

             Bug #: 15519
           Summary: GDB 7.6 is 94x slower than GDB 7.5.1 using a certain
                    core file
           Product: gdb
           Version: 7.6
            Status: NEW
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned@sourceware.org
        ReportedBy: psmith@gnu.org
    Classification: Unclassified


Please see this thread: http://sourceware.org/ml/gdb/2013-05/msg00074.html

I couldn't pick a particular component: the slowdown appears when running a
macro on a core file from a C++ program; the macro walks through a list of
objects referenced by another object.  Other core dumps from the same
executable do not show this slowdown, and so far we haven't been able to
reproduce it using live debugging.

Bisecting via Git declares the slowdown to have been introduced with this
commit:

677b1bfabd372790dca4dad32fcb05dd77658728 is the first bad commit
commit 677b1bfabd372790dca4dad32fcb05dd77658728
Author: Keith Seitz <keiths@redhat.com>
Date:   Fri Nov 16 20:54:28 2012 +0000


I'll see if I can get more details.

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[Bug c++/15519] GDB 7.6 is 94x slower than GDB 7.5.1 using a certain core file

[psmith at gnu dot org]

http://sourceware.org/bugzilla/show_bug.cgi?id=15519

--- Comment #1 from psmith at gnu dot org 2013-05-22 23:16:32 UTC ---
Created attachment 7037
  --> http://sourceware.org/bugzilla/attachment.cgi?id=7037
gprof output of FAST gdb run

This is the result of running gdb from the last "fast" commit,
e8127d61d885e62b8cd3bde1d1d0989819295268.  GDB built with -g -pg.

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[Bug c++/15519] GDB 7.6 is 94x slower than GDB 7.5.1 using a certain core file

[psmith at gnu dot org]

http://sourceware.org/bugzilla/show_bug.cgi?id=15519

--- Comment #2 from psmith at gnu dot org 2013-05-22 23:19:28 UTC ---
Created attachment 7038
  --> http://sourceware.org/bugzilla/attachment.cgi?id=7038
gprof output of SLOW gdb run

This is the result of running gdb from the first "slow" commit,
677b1bfabd372790dca4dad32fcb05dd77658728.  GDB built with -g -pg.

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[Bug c++/15519] GDB 7.6 is 94x slower than GDB 7.5.1 using a certain core file

[jan.kratochvil at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15519

Jan Kratochvil <jan.kratochvil at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jan.kratochvil at redhat dot com

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[Bug c++/15519] GDB 7.6 is 94x slower than GDB 7.5.1 using a certain core file

[jan.kratochvil at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15519

Jan Kratochvil <jan.kratochvil at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING

--- Comment #5 from Jan Kratochvil <jan.kratochvil at redhat dot com> ---
It seems to be fixed now, could you verify it, Paul?

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[Bug c++/15519] GDB 7.6 is 94x slower than GDB 7.5.1 using a certain core file

[psmith at gnu dot org]

http://sourceware.org/bugzilla/show_bug.cgi?id=15519

psmith at gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|---                         |FIXED

--- Comment #6 from psmith at gnu dot org ---
Thanks Jan; I tested this morning's snapshot (7.6.50.20130610) and the massive
slowdown is not there.  Nice!

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[Bug c++/15519] GDB 7.6 is 94x slower than GDB 7.5.1 using a certain core file

[cvs-commit at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=15519

--- Comment #7 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
CVSROOT:    /cvs/src
Module name:    src
Branch:     gdb_7_6-branch
Changes by:    devans@sourceware.org    2013-06-27 22:18:33

Modified files:
    gdb            : ChangeLog cp-namespace.c 
    gdb/testsuite  : ChangeLog 
    gdb/testsuite/gdb.cp: derivation.cc derivation.exp 
Added files:
    gdb/testsuite/gdb.cp: derivation2.cc 

Log message:
    PR 15519
    * cp-namespace.c (find_symbol_in_baseclass): Call
    cp_lookup_symbol_in_namespace instead of cp_lookup_symbol_namespace.
    Check result of call to lookup_symbol_static.
    Call lookup_static_symbol_aux unconditionally.
    Call check_typedef on base types before accessing them.
    (cp_lookup_nested_symbol): Fix comment.

    testsuite/
    * gdb.cp/derivation2.cc: New file.
    * gdb.cp/derivation.cc (main): Call foo2.
    * gdb.cp/derivation.exp: Add tests for typedefs in another
    file, and when there's an active block.

    testsuite/
    * gdb.cp/derivation.exp: Make tests have unique names.

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/ChangeLog.diff?cvsroot=src&only_with_tag=gdb_7_6-branch&r1=1.15260.2.55&r2=1.15260.2.56
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/cp-namespace.c.diff?cvsroot=src&only_with_tag=gdb_7_6-branch&r1=1.65.2.1&r2=1.65.2.2
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/ChangeLog.diff?cvsroot=src&only_with_tag=gdb_7_6-branch&r1=1.3580.2.22&r2=1.3580.2.23
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/gdb.cp/derivation2.cc.diff?cvsroot=src&only_with_tag=gdb_7_6-branch&r1=NONE&r2=1.2.2.2
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/gdb.cp/derivation.cc.diff?cvsroot=src&only_with_tag=gdb_7_6-branch&r1=1.5&r2=1.5.2.1
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/gdb.cp/derivation.exp.diff?cvsroot=src&only_with_tag=gdb_7_6-branch&r1=1.24&r2=1.24.2.1

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