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Re: GCC Status Report (2004-03-09)
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>
- Cc: ebotcazou at libertysurf dot fr, gcc-patches at gcc dot gnu dot org, gcc at gcc dot gnu dot org
- Date: Fri, 19 Mar 2004 03:14:18 -0500
- Subject: Re: GCC Status Report (2004-03-09)
- References: <10403190126.AA20411@vlsi1.ultra.nyu.edu>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Thu, Mar 18, 2004 at 08:26:30PM -0500, Richard Kenner wrote:
> I don't know what to think about /u overall. It's becoming more and more
> clear that it's the source of a lot of trouble and probably is becoming
> less and less useful with aliasing code around anyway. I'd be in favor
> of trying the experiment of only using it on data that's *never* explicitly
> stored (like constant-pool or items with static initializers). So we
> disallow stores to /u.
That would be certainly safest and the UNCHANGING would really mean
unchanging. But I hope we could at least extend it to objects which are
*never* stored into in current function (see if the object is initialized
in the function currently expanded into RTL, if not, use RTX_UNCHANGING_P
for it as well, otherwise perhaps use some other bit or alias set).