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. Committed in r12-939 as the suggested wordings. BR, Kewen
