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Re: [tree-ssa] Write to global memory not hoisted out of loop
- From: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- To: Richard Guenther <rguenth at tat dot physik dot uni-tuebingen dot de>
- Cc: Steven Bosscher <stevenb at suse dot de>, gcc at gcc dot gnu dot org
- Date: Fri, 30 Apr 2004 22:57:58 +0200
- Subject: Re: [tree-ssa] Write to global memory not hoisted out of loop
- References: <Pine.LNX.4.53.0404301458020.8230@bellatrix.tat.physik.uni-tuebingen.de>
Hello,
> > > Writes to global memory are not hoisted out of a computation loop.
> >
> > Try this with the LNO branch, iirc it can do this.
>
> Not as of gcc (GCC) 3.5-tree-ssa-lno 20040430 (merged 20040425) (-O2
> -ftree-loop-optimize -ffast-math), neither with static nor without.
tree-ssa aliasing probably does not take restricted pointers into
account, since it decides that all the accesses in the loop may alias.
Consequently none of the optimizations that could cause the store
to be hoisted out detects the possibility.
Zdenek