on 2021/9/18 上午6:26, Segher Boessenkool wrote: > Hi! > > On Wed, Sep 15, 2021 at 04:52:49PM +0800, Kewen.Lin wrote: >> This patch follows the discussion here[1], where Segher suggested >> parameterizing those exact magic constants for density heuristics, >> to make it easier to tweak if need. >> >> Since these heuristics are quite internal, I make these parameters >> as undocumented and be mainly used by developers. > > Okido. > >> + if (data->nloads > (unsigned int) rs6000_density_load_num_threshold >> + && load_pct > (unsigned int) rs6000_density_load_pct_threshold) > > Those variables are unsigned int already. Don't cast please. >
Unfortunately this is required by bootstrapping. The UInteger for the param definition is really confusing, in the underlying implementation it's still "signed". If you grep "(unsigned) param", you can see a few examples. I guess the "UInteger" is mainly for the param value range checking. >> +-param=rs6000-density-pct-threshold= >> +Target Undocumented Joined UInteger Var(rs6000_density_pct_threshold) >> Init(85) IntegerRange(0, 99) Param > > So make this and all other percentages (0, 100) please. > I thought 99 is enough for the RHS in ">". just realized it's more clear with 100. Will fix! >> +When costing for loop vectorization, we probably need to penalize the loop >> body cost if the existing cost model may not adequately reflect delays from >> unavailable vector resources. We collect the cost for vectorized statements >> and non-vectorized statements separately, check the proportion of vec_cost >> to total cost of vec_cost and non vec_cost, and penalize only if the >> proportion exceeds the threshold specified by this parameter. The default >> value is 85. > > It would be good if we can use line breaks in the source code for things > like this, but I don't think we can. This message is mainly used for > "--help=param", and it is good there to have as short messages as you > can. But given the nature of params you need quite a few words often, > and you do not want to say so little that things are no clear, either. > > So, dunno :-) I did some testings, the line breaks writing can still survive in the "--help=param" show, the lines are concatenated with " ". Although there seems no this kind of writing practices, I am guessing you want me to do line breaks for their descriptions? If so, I will make them short as the above "Target Undocumented..." line. Or do you want it to align source code ColumnLimit 80 (for these cases, it would look shorter)? > > Oksy for trunk with these fixes and what Bill mentioned in the other > thread. Thanks! > OK, thanks again! BR, Kewen
