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Re: Alias Analysis Improvement Patch
- From: "Vladimir N. Makarov" <vmakarov at redhat dot com>
- To: law at redhat dot com
- Cc: Andreas Jaeger <aj at suse dot de>,"Sanjiv Kumar Gupta, Noida" <sanjivg at noida dot hcltech dot com>,gcc-patches at gcc dot gnu dot org
- Date: Fri, 13 Jun 2003 12:04:38 -0400
- Subject: Re: Alias Analysis Improvement Patch
- References: <200306120131.h5C1V18l015976@speedy.slc.redhat.com>
law@redhat.com wrote:
>
> >So I think this patch is not for approval in near future but for its
> >investigation. I am going to look at this patch for ia64 platform.
> Let me know what you find.
>
I've tried the patch on Itanium2 machine for the mainline gcc. I've got the
following results (the right column is for gcc with the new aliasing).
164.gzip 1400 366 383* 1400 367 382*
175.vpr 1400 303 463* 1400 305 459*
176.gcc X X
181.mcf 1800 717 251* 1800 715 252*
186.crafty 1000 199 503* 1000 198 506*
197.parser 1800 494 364* 1800 496 363*
252.eon 1300 475 273*
253.perlbmk 1800 370 487* 1800 372 484*
254.gap 1100 331 332* 1100 331 333*
255.vortex 1900 324 586* 1900 325 585*
256.bzip2 1500 393 382* 1500 393 382*
300.twolf 3000 561 535* 3000 625 480*
Code for eon generated with the new alias analysis works incorrectly.
In average gcc with the patch is worse especially for twolf. I think I
should search for the reason of degradation in counteraction of scheduler
and alias analysis.
The compiler is also slower ~25% (890s vs 1140 s) with the new alias
analysis on SPECINT2000.
I did not check the code size (it is not important for Itanium).
Practically the same picture is for SPECFP2000 tests (new aliasing results
in incorrect work of 4 tests).
Although I've found a test when the patch gives a big improvement (2%). It
is whetstone
Sanjiv, the results are frustrated ones but I am not giving up. I'll work
on it. Alias analysis is important thing. Theoretically it is better
approach then SSA one because it is flow sensitive. So I am going to find
what is wrong with the results. Although I am not sure that it will happen
soon.
Another thing is we should speed up it considerably to justify the patch
adoption.
Vlad