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Re: Serious performance regression -- some tree optimizer questions
- From: Ulrich Weigand <Ulrich dot Weigand at de dot ibm dot com>
- To: Mircea Namolaru <NAMOLARU at il dot ibm dot com>
- Cc: Ayal Zaks <ZAKS at il dot ibm dot com>, dberlin at dberlin dot org, dje at watson dot ibm dot com, gcc at gcc dot gnu dot org, Leehod Baruch <LEEHOD at il dot ibm dot com>, rakdver at atrey dot karlin dot mff dot cuni dot cz
- Date: Thu, 13 Jan 2005 15:45:20 +0100
- Subject: Re: Serious performance regression -- some tree optimizer questions
Mircea Namolaru/Haifa/IBM wrote on 01/13/2005 03:12:13 PM:
> >> IBM Haifa has some patches waiting for GCC 4.1 to address sign
> >> extension problems.
> > Zdenek's latest patch addressed all sign-extension problems
> > I've been seeing with my test case -- are the Haifa patches
> > concerned with the same issues or different ones?
> Regarding our intended patch you can look at:
> - The overview of the algorithm:
> - The RFC for the implementation:
Thanks for the pointers. It does look that these patches
address a completely different issue; they do not change
the type of a variable (which is what causes the overflow
semantics problems), but solely try to optimize the placement
of sign-extend operations. Also, the pass apparently will
operate on RTL, while I was disussing issues in the tree
loop optimizer ...
So, your patches look certainly valuable (in fact I think
they'll most likely benefit s390 as well), but are completely
unrelated to the problem I raised in this thread (and which
Zdenek's latest patch solves for me).
Mit freundlichen Gruessen / Best Regards
Dr. Ulrich Weigand
Linux for S/390 Design & Development
IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032 Boeblingen
Phone: +49-7031/16-3727 --- Email: Ulrich.Weigand@de.ibm.com