RE: Polyhedron test: gas_dyn run-time performance regression compared with yesterday

["Jagasia, Harsha" <harsha dot jagasia at amd dot com>]

>> Result from http://www.suse.de/~gcctest/c++bench/polyhedron/
>> -ffast-math -funroll-loops -O3 -ftree-vectorize -march= ??? (opteron
I
>> think).
>> 14.59s -> 21.06s (44% slower)
>

I will look into it right now, but at first glance it does not look like
this benchmark is built with the cost model enabled.


Thanks,

>
>> Result on for my AMD Athlon64 4800+,
>> http://physik.fu-berlin.de/~tburnus/gcc-trunk/benchmark/
>> Yesterday: 2007-09-10-r128322
>> Today: 2007-09-11-r128363
>
>The problem was introduced by r128353 [1]:
>
>2007-09-10  Harsha Jagasia <harsha.jagasia@amd.com>
>            Jan Sjodin <jan.sjodin@amd.com>
>
>        * tree-vect-analyze.c (vect_analyze_operations): Change
>        comparison of loop iterations with threshold to less than
>        or equal to instead of less than. Reduce
>        min_scalar_loop_bound by one.
>        * tree-vect-transform.c (vect_estimate_min_profitable_iters):
>        Change prologue and epilogue iterations estimate to vf/2,
>        when unknown at compile-time. Change versioning guard
>        cost to taken_branch_cost. If peeling for alignment is
>        unknown at compile-time, change peel guard costs to one
>        taken branch and one not-taken branch per peeled loop.
>        If peeling for alignment is known but number of scalar loop
>        iterations is unknown at compile-time, change peel guard
>        costs to one taken branch per peeled loop. Change the cost
>        model equation to consider vector iterations as the loop
>        iterations less the prologue and epilogue iterations.
>        Change outside vector cost check to less than or equal to
>        zero instead of equal to zero.
>        (vect_do_peeling_for_loop_bound): Reduce
>        min_scalar_loop_bound by one.
>        * tree-vectorizer.h: Add TARG_COND_TAKEN_BRANCH_COST and
>        TARG_COND_NOT_TAKEN_BRANCH_COST.
>        ...
>
>[1]: http://gcc.gnu.org/ml/gcc-cvs/2007-09/msg00347.html
>
>Uros.
>