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Re: inline functions

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On Wednesday, November 28 2012, Ben Pfaff wrote:

> James Kuyper <jameskuyper@verizon.net> writes:
>
>> It's not just a matter of ancient compilers that can't combine debugging
>> with optimization. In my experience, debugging code that has been
>> significantly optimized is both quite possible, and exceedingly
>> difficult, because the code that I'm watching behaves quite differently
>> from the code that I wrote. One of the first things I do, when debugging
>> appears to be necessary, is to determine whether the bug disappears when
>> optimizations are turned off. If it doesn't, I normally leave them
>> turned off during debugging, for the sake of my own sanity.
>
> Yesterday I noticed this in the GCC 4.8 changes:
>
>     A new general optimization level, -Og, has been introduced.
>     It addresses the need for fast compilation and a superior
>     debugging experience while providing a reasonable level of
>     runtime performance.  Overall experience for development
>     should be better than the default optimization level -O0.

Yeah, the -Og flag has been discussed for quite some time, but it is
still pretty recent and may need some improvements, of course.

Anyway, this subject (debugging optimized programs) is interesting,
difficult, and there are some good approaches that try to address it.
One of the most recent projects is what we call "Variable-tracking at
assignments", a project from Alexandre Oliva at Red Hat, which aims to
improve the debugging experience for local variables that have been
optimized out.  It's a pretty good attempt to tackle some subset of the
whole problem.

More about it: http://gcc.gnu.org/wiki/Var_Tracking_Assignments

I am a GDB developer, and when I talk to people about whether they
should disable optimizations or not, I often say that they should.
"Compile your program with -O0 -g3", I say.  But fortunately, given the
efforts being made on the compiler front, even -O2 programs have better
debuginfo today than they used to some years ago.

-- 
Sergio

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inline functions "BartC" <bc@freeuk.com> - 2012-11-24 12:20 +0000
  Re: inline functions SG <sgesemann@gmail.invalid> - 2012-11-24 14:52 +0100
    Re: inline functions "BartC" <bc@freeuk.com> - 2012-11-24 14:48 +0000
      Re: inline functions Joost Kraaijeveld <J.Kraaijeveld@Askesis.nl> - 2012-11-24 15:59 +0100
      Re: inline functions Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2012-11-24 16:25 +0100
      Re: inline functions Johann Klammer <klammerj@NOSPAM.a1.net> - 2012-11-24 19:18 +0100
  Re: inline functions Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-11-24 15:07 +0000
    Re: inline functions "BartC" <bc@freeuk.com> - 2012-11-24 15:33 +0000
      Re: inline functions Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2012-11-24 17:17 +0100
        Re: inline functions "BartC" <bc@freeuk.com> - 2012-11-24 16:39 +0000
          Re: inline functions Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2012-11-24 18:13 +0100
            Re: inline functions Jens Gustedt <jens.gustedt@loria.fr> - 2012-11-24 19:36 +0100
              Re: inline functions Sergio Durigan Junior <sergiodj@riseup.net> - 2012-12-05 03:19 -0200
                Re: inline functions Jens Gustedt <jens.gustedt@loria.fr> - 2012-12-05 10:57 +0100
                Re: inline functions Sergio Durigan Junior <sergiodj@riseup.net> - 2012-12-05 15:34 -0200
        Re: inline functions Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-11-25 09:43 +0000
          Re: inline functions Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2012-11-25 11:32 +0100
            Re: inline functions Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-11-27 21:55 +0000
        Re: inline functions "christian.bau" <christian.bau@cbau.wanadoo.co.uk> - 2012-11-26 04:16 -0800
          Re: inline functions David Brown <david@westcontrol.removethisbit.com> - 2012-11-26 14:13 +0100
            Re: inline functions Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-11-28 21:27 +0000
              Re: inline functions James Kuyper <jameskuyper@verizon.net> - 2012-11-28 16:40 -0500
                Re: inline functions Ben Pfaff <blp@cs.stanford.edu> - 2012-11-28 14:15 -0800
                Re: inline functions Sergio Durigan Junior <sergiodj@riseup.net> - 2012-11-29 00:02 -0200
                Re: inline functions Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-29 07:24 -0800
                Re: inline functions James Kuyper <jameskuyper@verizon.net> - 2012-11-29 11:04 -0500
                Re: inline functions Sergio Durigan Junior <sergiodj@riseup.net> - 2012-11-29 14:44 -0200
                Re: inline functions Les Cargill <lcargill99@comcast.com> - 2012-11-29 12:44 -0600
                Re: inline functions Sergio Durigan Junior <sergiodj@riseup.net> - 2012-11-29 20:43 -0200
                Re: inline functions Les Cargill <lcargill99@comcast.com> - 2012-11-29 20:14 -0600
                Re: inline functions Ian Collins <ian-news@hotmail.com> - 2012-11-30 07:44 +1300
                Re: inline functions Sergio Durigan Junior <sergiodj@riseup.net> - 2012-11-29 20:38 -0200
                Re: inline functions Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-12-05 03:17 +0000
                Re: inline functions Noob <root@127.0.0.1> - 2012-12-05 11:26 +0100
      Re: inline functions David Brown <david@westcontrol.removethisbit.com> - 2012-11-26 11:23 +0100
        Re: inline functions "BartC" <bc@freeuk.com> - 2012-11-26 13:01 +0000
          Re: inline functions David Brown <david@westcontrol.removethisbit.com> - 2012-11-26 14:24 +0100
            Re: inline functions Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-26 05:35 -0800
              Re: inline functions Les Cargill <lcargill99@comcast.com> - 2012-11-26 07:57 -0600
                Re: inline functions Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-26 07:07 -0800
              Re: inline functions Rosario1903 <Rosario@invalid.invalid> - 2012-11-27 09:46 +0100
              Re: inline functions David Brown <david@westcontrol.removethisbit.com> - 2012-11-27 10:50 +0100
            Re: inline functions "BartC" <bc@freeuk.com> - 2012-11-26 14:14 +0000
              Re: inline functions "BartC" <bc@freeuk.com> - 2012-11-26 15:14 +0000
              Re: inline functions Rosario1903 <Rosario@invalid.invalid> - 2012-11-27 09:46 +0100
                Re: inline functions "BartC" <bc@freeuk.com> - 2012-11-27 14:41 +0000
              Re: inline functions David Brown <david@westcontrol.removethisbit.com> - 2012-11-27 11:01 +0100
                Re: inline functions "BartC" <bc@freeuk.com> - 2012-11-27 14:37 +0000
                Re: inline functions Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2012-11-27 18:22 +0100
                Re: inline functions James Kuyper <jameskuyper@verizon.net> - 2012-11-27 12:55 -0500
                Re: inline functions Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-11-27 22:06 +0000
                Re: inline functions David Brown <david@westcontrol.removethisbit.com> - 2012-11-29 09:47 +0100
          Re: inline functions glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-11-26 14:39 +0000
  Re: inline functions Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-11-24 07:20 -0800
    Re: inline functions James Kuyper <jameskuyper@verizon.net> - 2012-11-24 10:44 -0500
  Re: inline functions James Kuyper <jameskuyper@verizon.net> - 2012-11-24 10:35 -0500
  Re: inline functions Philip Lantz <prl@canterey.us> - 2012-11-24 22:56 -0800
  Re: inline functions James Dow Allen <jdallen2000@yahoo.com> - 2012-11-25 01:18 -0800

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