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Re: Optimising std::find on x86 and PPC
- From: Gabriel Dos Reis <gdr at integrable-solutions dot net>
- To: Paolo Carlini <pcarlini at suse dot de>
- Cc: Theodore Papadopoulo <Theodore dot Papadopoulo at sophia dot inria dot fr>, Chris Jefferson <caj at cs dot york dot ac dot uk>, gcc at gcc dot gnu dot org, libstdc++ <libstdc++ at gcc dot gnu dot org>, Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- Date: 14 Dec 2004 22:40:53 +0100
- Subject: Re: Optimising std::find on x86 and PPC
- Organization: Integrable Solutions
- References: <200412141909.iBEJ9XZ7027097@mururoa.inria.fr><41BF4753.3070803@suse.de> <41BF4E0F.5020703@suse.de>
Paolo Carlini <pcarlini@suse.de> writes:
| Paolo Carlini wrote:
|
| > Hi Theodore and thanks for the interesting analysis.
|
| I would like to add, that both gcc3.3.3 and other compilers are
| definitely able to unroll the loop at issue, therefore I'm tempted to
| consider the current behavior just a serious (performance) regression
| (i.e., correctness vs aliasing and other subtleties should not be in
| the way)
That is a clear regression.
Tree-ssa has been sold on the name of bringing better methodology to
optimizations; given Theo's analysis, I think this issue no longer
belongs to V3. It should be brought to GCC main list
-- Gaby