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Re: undocumented optimization options
- From: "Richard Guenther" <richard dot guenther at gmail dot com>
- To: "Razya Ladelsky" <RAZYA at il dot ibm dot com>
- Cc: "Mark Mitchell" <mark at codesourcery dot com>, ctice at apple dot com, gcc at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org, "Gerald Pfeifer" <gerald at pfeifer dot com>, "Janis Johnson" <janis187 at us dot ibm dot com>, stevenb dot gcc at gmail dot com, "Kenneth Zadeck" <zadeck at naturalbridge dot com>
- Date: Tue, 20 Nov 2007 13:51:51 +0100
- Subject: Re: undocumented optimization options
- References: <47387E5F.email@example.com> <OFE58B8D7A.029CA307-ONC2257399.003D2164-C2257399.003F2FAB@il.ibm.com>
On Nov 20, 2007 12:32 PM, Razya Ladelsky <RAZYA@il.ibm.com> wrote:
> Mark Mitchell <firstname.lastname@example.org> wrote on 12/11/2007 18:25:03:
> > Richard Guenther wrote:
> > > For options that are not enabled by default at any -O level the
> > documentation
> > > should be a help for the user to decide whether to enable or not
> enable it.
> > > So, yes, if there are non-standard terms used or if there are not
> > > side-effects (like performing function versioning for ipa-cp)
> > those should be
> > > documented.
> > >
> > > For example googling for "interprocedural constant propagation" gives
> > > an idea what it does by citing papers. Googling for "matrix
> > > transposing" instead gives you only patches ;)
> > To echo Richard: this is a user manual, so we don't need to say exactly
> > what the option does, but we have to say when you should use it. :-) In
> > other words, we certainly don't want to say anything about SSA names or
> > whatever, but we do want to explain what it's for. For interprocedural
> > constant propagation, maybe something like:
> > ==
> > This optimization analyzes the program to determine when values passed
> > to, or return from, functions are constants and then optimizes
> > accordingly. This optimization can substantially increase performance
> > if the application has lots of functions that return constants, but,
> > because this optimization can create multiple copies of code fragments,
> > it may significantly increase code size.
> > ==
> Described these two optimizations in more detail.
> O.K now?
> 2007-11-20 Razya Ladelsky <email@example.com>
> * doc/invoke.texi (fipa-cp, fipa-matrix-reorg): Add documentation.