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Re: [PATCH, rs6000 v2] Make load cost more in vectorization cost for P8/P9
On Thu, Nov 07, 2019 at 11:22:12AM +0800, Kewen.Lin wrote:
> One updated patch to enable it everywhere attached.
> 2019-11-07 Kewen Lin <linkw@gcc.gnu.org>
>
> * config/rs6000/rs6000.c (rs6000_builtin_vectorization_cost): Make
> scalar_load, vector_load, unaligned_load and vector_gather_load cost
> more to conform hardware latency and insn cost settings.
> case unaligned_load:
> case vector_gather_load:
...
> - /* Word aligned. */
> - return 22;
> + /* Word aligned. */
> + return 44;
I don't think it should go up from 22 all the way to 44 (not all insns here
are loads). But exact cost doesn't really matter. Make it 30 perhaps?
44 (as well as 22) are awfully precise numbers for a very imprecise cost
like this ;-)
With either cost, whatever seems reasonable to you and works well in your
tests: approved for trunk. Thanks!
Segher