This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: C compile time
- From: Richard Guenther <rguenth at tat dot physik dot uni-tuebingen dot de>
- To: Mark Mitchell <mark at codesourcery dot com>
- Cc: gcc at gcc dot gnu dot org, <jh at suse dot cz>, Benjamin Kosnik <bkoz at redhat dot com>
- Date: Thu, 19 Jun 2003 16:41:48 +0200 (CEST)
- Subject: Re: C compile time
>> It would be nice if some of the inlining issues got sorted out for 3.4,
>> and -Winline became deterministic again.
>
>For 3.4, we could consider going back to the "bottom-up" inlining
>strategy. That might be better than what we have now, even though it's
>inherently quadratic. Implementing bottom-up inlining wouldn't be
>terribly hard; all the same tree-inlining machinery would work.
>
>One of the things we seem to forget in all the inlining discussion is
>that inlining has never worked well. In fact, one of the big
>motivations in going to function-at-a-time was to try to fix all the
>lameness in the RTL inliner! On many large C++ programs, the 2.95 era
>compilers would simply exhaust all memory trying to do inlining...
>
>I'm pretty convinced that there's no easy fix, unfortunately.
I think at least with a callgraph available we can do better. Also
implementing more user hints (like __attribute__((leafify))) correctly
needs a callgraph due to our function deffering stuff.
Richard.