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[Bug c++/33604] [4.3 Regression] Revision 119502 causes significantly slower results with 4.3 compared to 4.2
- From: "bonzini at gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 6 Nov 2007 21:23:03 -0000
- Subject: [Bug c++/33604] [4.3 Regression] Revision 119502 causes significantly slower results with 4.3 compared to 4.2
- References: <bug-33604-15171@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #11 from bonzini at gnu dot org 2007-11-06 21:23 -------
michael dot olbrich at gmx dot net wrote:
> ------- Comment #10 from michael dot olbrich at gmx dot net 2007-11-06 21:01 -------
> 4.2 4.3 |
> ---------------
> 4.4s 15.9s |-O3
> 4.6s 16.3s |-O3 -fno-tree-vectorize
> X 18.9s |-O3 -fno-predictive-commoning
This is *good* news. :-) New optimizations in GCC 4.3 save 15% of the runtime.
It is then only an aliasing problem, maybe due to extra vdefs/vuses. I
haven't look at the code but, anyway, Danny/Diego---would a patch like this
make sense?
/* Since we clearly cannot lower the number of virtual operators
below the total number of memory statements in the function, we
may need to adjust MAX_ALIASED_VOPS beforehand. */
- if (MAX_ALIASED_VOPS < mem_ref_stats->num_mem_stmts)
- MAX_ALIASED_VOPS = mem_ref_stats->num_mem_stmts;
+ if (MAX_ALIASED_VOPS < mem_ref_stats->num_mem_stmts * AVG_ALIASED_VOPS)
+ MAX_ALIASED_VOPS = mem_ref_stats->num_mem_stmts * AVG_ALIASED_VOPS;
--
bonzini at gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |dnovillo at gcc dot gnu dot
| |org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33604