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From: "mhov at undo dot io" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug gdb/27979] New: Performance regression of ~10% in conditional
 breakpoint testcase
Date: Mon, 14 Jun 2021 12:44:46 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D27979

            Bug ID: 27979
           Summary: Performance regression of ~10% in conditional
                    breakpoint testcase
           Product: gdb
           Version: 10.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: mhov at undo dot io
  Target Milestone: ---

Created attachment 13491
  --> https://sourceware.org/bugzilla/attachment.cgi?id=3D13491&action=3Ded=
it
reproducer program

There seems to be a performance regression from 9.2 to 10.2 that is observa=
ble
in the time to run the following command on the attached reproducer program.
This has been used to benchmark the performance of conditional breakpoints.

  $ gcc --version
    gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0
  $ gcc -g repro.c
  $ ./gdb --batch --ex "b foo if bar=3D=3D0x7ffffff" --ex "run" --args ./a.=
out

Also attached is a log from the libera.chat #gdb channel where this regress=
ion
was discussed.

As can be seen in the attached chat log, bisection by Simon suggests that t=
his
commit is to blame:
https://sourceware.org/git/gitweb.cgi?p=3Dbinutils-gdb.git;h=3D1009d92fc621=
bc4d017029b90a5bfab16e17fde5

I'm not currently in a position to delve deeper into this, so I'm posting h=
ere
in case anyone wants to pick it up.

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