On Thu, 20 May 2021 at 10:52, Kewen.Lin via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> on 2021/5/19 下午6:01, Richard Biener wrote:
> > On Wed, May 19, 2021 at 11:47 AM Kewen.Lin <li...@linux.ibm.com> wrote:
> >>
> >> Hi Richi,
> >>
> >> on 2021/5/19 下午4:15, Richard Biener wrote:
> >>> On Wed, May 19, 2021 at 8:20 AM Kewen.Lin <li...@linux.ibm.com> wrote:
> >>>>
> >>>> Hi,
> >>>>
> >>>> This patch is to replace the current hardcoded weight factor 50
> >>>> for those statements in an inner loop relative to the loop being
> >>>> vectorized with a specific parameter vect-inner-loop-weight-factor.
> >>>>
> >>>> The motivation behind this change is: if targets want to have one
> >>>> unique function to gather some information in each add_stmt_cost
> >>>> call, no matter that it's put before or after the cost tweaking
> >>>> part for inner loop, it may have the need to adjust (expand or
> >>>> shrink) the gathered data as the factor. Now the factor is
> >>>> hardcoded, it's not easily maintained. Since it's possible that
> >>>> targets have their own decisions on this costing like the others,
> >>>> I used parameter instead of one unique macro here.
> >>>>
> >>>> Testing is ongoing, is it ok for trunk if everything goes well?
> >>>
> >>> Certainly an improvement. I suppose we might want to put
> >>> the factor into vinfo->inner_loop_cost_factor. That way
> >>> we could adjust it easily in common code in the vectorizer
> >>> when we for example have (non-guessed) profile data.
> >>>
> >>> "weight_factor" is kind-of double-speak and I'm missing 'cost' ...
> >>> so, bike-shedding to vect_inner_loop_cost_factor?
> >>>
> >>> Just suggestions - as said, the patch is an improvement already.
> >>>
> >>
> >> Thanks for your nice suggestions! I've updated the patch accordingly
> >> and attached it. Does it look better to you?
> >
> > Minor nit:
> >
> > +@item vect-inner-loop-cost-factor
> > +The factor which loop vectorizer uses to over weight those statements in
> > +an inner loop relative to the loop being vectorized.
> > +
> >
> > the default value should be documented here, not..
> >
> > +-param=vect-inner-loop-cost-factor=
> > +Common Joined UInteger Var(param_vect_inner_loop_cost_factor)
> > Init(50) IntegerRange(1, 999999) Param Optimization
> > +Indicates the factor which loop vectorizer uses to over weight those
> > statements in an inner loop relative to the loop being vectorized.
> > The default value is 50.
> > +
> >
> > here (based on statistical analysis of existing cases). Also the
> > params.opt docs
> > should be the "brief" one - but for simplicity simply make both docs
> > identical
> > (apart from the default value doc). I suggest
> >
> > "The factor which the loop vectorizer applies to the cost of statements
> > in an inner loop relative to the loop being vectorized."
> >
>
> Thanks for catching this and the suggestion!
>
> Bootstrapped/regtested on powerpc64le-linux-gnu P9, x86_64-redhat-linux
> and aarch64-linux-gnu.
>
This breaks the build for arm targets:
/tmp/158661_3.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/config/arm/arm.c:
In function 'unsigned int arm_add_stmt_cost(vec_info*, void*, int,
vect_cost_for_stmt, _stmt_v
ec_info*, tree, int, vect_cost_model_location)':
/tmp/158661_3.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/config/arm/arm.c:12230:4:
error: 'loop_vec_info' was not declared in this scope
loop_vec_info loop_vinfo = dyn_cast<loop_vec_info> (vinfo);
^
/tmp/158661_3.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/config/arm/arm.c:12230:18:
error: expected ';' before 'loop_vinfo'
loop_vec_info loop_vinfo = dyn_cast<loop_vec_info> (vinfo);
Can you fix it?
Thanks,
Christophe
> Committed in r12-939 as the suggested wordings.
>
> BR,
> Kewen
