3.4 / 3.5 / tree-ssa comparisons

[Andrew Pinski]

On Apr 3, 2004, at 15:49, Richard Guenther wrote:

> The automated tester at  
> http://www.tat.physik.uni-tuebingen.de/~rguenth/gcc/monitor- 
> summary.html
> completed its first 3.5 build.  I never checked 3.5, and so I'm  
> surprised on the numbers it got:
>
> bootstrap time (52min) is inbetween 3.4 (50min) and tree-ssa (62min),  
> build times for the tramp3d-v3 test, too(!), I did expect them to  
> improve compared to 3.4, not already regress again..., they are now
> 2.43min vs. 2.28min (3.4) and 2.75min (tree-ssa).  Also performance of  
> the resulting binary is better(!) for 3.5 (6.9s/it) than for tree-ssa  
> (7.68s/it) and of course 3.4 is slowest (8.85s/it).  This means we'll  
> regress in both compile and runtime if merging tree-ssa now, but we  
> won't have a runtime regression towards 3.4 then, only a compile time  
> performance regression.
>
> The obvious question is, why is 3.5 so much better than 3.4?  And of  
> course, why is tree-ssa not better than 3.5 for C++ expression  
> template numeric code?

You could check the tree-ssa with my patch at  
<http://gcc.gnu.org/ml/gcc-patches/2004-04/msg00169.html>,
it should give both a runtime improvement and a compile time  
improvement.


Thanks,
Andrew Pinski