Enabling -ftree-slp-vectorize on -O2/Os

[Allan Sandfeld Jensen]

On Montag, 28. Mai 2018 12:58:20 CEST Richard Biener wrote:
> compile-time effects of the patch on that. Embedded folks may want to rhn
> their favorite benchmark and report results as well.
> 
> So I did a -O2 -march=haswell [-ftree-slp-vectorize] SPEC CPU 2006 compile
> and run and the compile-time
> effect where measurable (SPEC records on a second granularity) is within
> one second per benchmark
> apart from 410.bwaves (from 3s to 5s)  and 481.wrf (76s to 78s).
> Performance-wise I notice significant
> slowdowns for SPEC FP and some for SPEC INT (I only did a train run
> sofar).  I'll re-run with ref input now
> and will post those numbers.
> 
If you continue to see slowdowns, could you check with either no avx, or with 
-mprefer-avx128? The occational AVX256 instructions might be downclocking the 
CPU. But yes that would be a problem for this change on its own.

'Allan