This is the mail archive of the
mailing list for the GCC project.
Re: [tree-ssa] cfg.texi needs reviewing by a native speaker (Was: Re: "Documentation by paper")
- From: law at redhat dot com
- To: Jan Hubicka <jh at suse dot cz>
- Cc: Jan Hubicka <hubicka at ucw dot cz>, Steven Bosscher <stevenb at suse dot de>, Robert Dewar <dewar at gnat dot com>, Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>, gcc-patches at gcc dot gnu dot org, dnovillo at redhat dot com
- Date: Mon, 09 Feb 2004 15:58:49 -0700
- Subject: Re: [tree-ssa] cfg.texi needs reviewing by a native speaker (Was: Re: "Documentation by paper")
- Reply-to: law at redhat dot com
In message <20040209223920.GP20341@kam.mff.cuni.cz>, Jan Hubicka writes:
>> For example, the code to predict goto as not being executed simply doesn't
>> exist in the tree-ssa code. I'll also note that adding this predictor
>> actually makes things significantly worse for perl.
>Isn't it because the GOTOs are inserted/removed randomly during
>gimplification/optimization so this info simply don't make sense
>anymore? It works only when GOTOs writen by users are predicted by this
No, the code doesn't exist at all.
And if you insert it (carefully making sure that it only applies to user
written gotos) then it still loses badly. I haven't investigated why.
>> And it would seem to me that the looping predictors should be independent
>> of the gimplification code. Can you explain why they are not?
>They are using the continue hint
True, but we should be able to do something that is very similar (though
not exact) using the loop discovery and analysis code.
> and also know that copied loop headers
Well, the tree-ssa branch copies loop headers quite effectivel now.
However, we don't create preheaders, which is a problem unto itself, but
which as far as I can tell doesn't make a difference on the prediction
>See analyze_brprob script in the contrib directory. It has some info
>about use in it and you can see data collected by profiled tester at
>http://www.suse.de/~aj/SPEC (see result files and analyze_brprob