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Re: Put scope blocks on a diet
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: "Richard Guenther" <richard dot guenther at gmail dot com>
- Cc: "Jan Hubicka" <hubicka at ucw dot cz>, "Jan Hubicka" <jh at suse dot cz>, gcc-patches at gcc dot gnu dot org, "Mark Mitchell" <mark at codesourcery dot com>
- Date: Tue, 27 Nov 2007 20:56:38 -0200
- Subject: Re: Put scope blocks on a diet
- References: <orlkcucny9.fsf@oliva.athome.lsd.ic.unicamp.br> <orprznl6tl.fsf@free.oliva.athome.lsd.ic.unicamp.br> <20071010084624.GA19060@atrey.karlin.mff.cuni.cz> <orzlyqjhq1.fsf@free.oliva.athome.lsd.ic.unicamp.br> <84fc9c000710110138i7e541407p26ff63fbcc76028a@mail.gmail.com> <20071011221238.GN20381@kam.mff.cuni.cz> <orir5dglqw.fsf@free.oliva.athome.lsd.ic.unicamp.br> <20071012061351.GA11752@atrey.karlin.mff.cuni.cz> <84fc9c000711270520n4e75f4b5idc1a8327f0ad2ba2@mail.gmail.com> <oroddfbis2.fsf@oliva.athome.lsd.ic.unicamp.br> <84fc9c000711271244w647cec69tc9332737bb0c7ef7@mail.gmail.com>
On Nov 27, 2007, "Richard Guenther" <richard.guenther@gmail.com> wrote:
> I agree here. I am currently evaluating what just reverting the following ...
>> 2. this patch delays the garbage-collection of some declarations after
>> inlining,
> ... part of the patch does to the memory usage regression.
If you're compiling with -g, it won't do anything at all, for the
!cfun->after_inlining is never even reached when debug_info_level >=
DINFO_LEVEL_NORMAL.
Also, please don't call it a memory usage regression. It's offensive.
If a patch unintentionally dropped entire basic blocks went in and
remained unfixed for months, would the fix that stops them from being
dropped be regarded as a regression in memory usage? This is
ridiculous!
Let's please revert the patch that introduced the bug in the first
place. Then we can make an assessment of how much the memory
optimization patch actually gets us without anyone being confused by
the distortions caused by the bug in the patch.
> This part doesn't fix a regression
I don't understand how you got this mistaken impression. Without this
part of the patch, or something equivalent, the regression in the
property that -g and -g0 emit the same code, introduced by Honza's
initial patch, remains. This fundamental property held before his
patch, and it stopped holding afterwards.
Do we consciously want to break this for GCC 4.3?
Also, considering how much scope information that patch causes us to
unintentionally discard, do we consciously want to introduce such a
major debug information regression in GCC 4.3, even with -O0?
--
Alexandre Oliva http://www.lsd.ic.unicamp.br/~oliva/
FSF Latin America Board Member http://www.fsfla.org/
Red Hat Compiler Engineer aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist oliva@{lsd.ic.unicamp.br, gnu.org}