> ------------------------------------------------------------------
> Sender:Richard Biener <richard.guent...@gmail.com>
> Sent At:2019 Apr. 29 (Mon.) 20:01
> Recipient:bin.cheng <bin.ch...@linux.alibaba.com>
> Cc:GCC Patches <gcc-patches@gcc.gnu.org>; mliska <mli...@suse.cz>
> Subject:Re: [PATCH PR90240][RFC]Avoid scaling cost overflow by introducing
> scaling bound
>
>
> On Sat, Apr 27, 2019 at 6:13 AM bin.cheng <bin.ch...@linux.alibaba.com> wrote:
> >
> > > Hi,
> >
> > This is the draft patch avoiding scaling cost overflow by introducing a
> > scaling bound
> > in IVOPTs. For now the bound is 20, and scaling factor will be further
> > scaled wrto
> > this bound. For example, scaling factor like 1, 1000, 2000(max) would be
> > scaled to
> > 1, 10, 20 correspondingly.
> >
> > HI Martin, I remember you introduced comp_cost/cost_scaling to improve one
> > case
> > in spec2017. Unfortunately I don't have access to the benchmark now, could
> > you help
> > verify that if this patch has performance issue on it please? Thanks
> >
> > Bootstrap and test on x86_64, and this is for further comment/discussion.
>
> + float factor = 1.0f * bfreq / lfreq;
> + if (adjust_factor_p)
> + {
> + factor *= COST_SCALING_FACTOR_BOUND;
> + factor = factor * lfreq / max_freq;
> + }
> + body[i]->aux = (void *)(intptr_t)(int) factor;
>
> float computations on the host shouldn't be done.
Fixed.
>
> I wonder if changing comp_cost::cost to int64_t would help instead? See also
> my
> suggestion to use gmp.
Next patch for PR90078 changes the cost to int64_t.
>
> Otherwise the approach looks sane to me - can we then even assert that
> no overflows
> happen and thus INFTY only appears if we manually set such cost?
Next patch for PR90078 changes to assert on cost overflow.
Attachment is the updated patch. Bootstrap/test on x86_64 along with PR90078
patch.
Is it OK?
Thanks,
bin
2019-05-05 Bin Cheng <bin.ch...@linux.alibaba.com>
PR tree-optimization/90240
* tree-ssa-loop-ivopts.c (get_scaled_computation_cost_at): Scale cost
with respect to scaling factor pre-computed for each basic block.
(try_improve_iv_set): Return bool if best_cost equals to iv_ca cost.
(find_optimal_iv_set_1): Free iv_ca set if it has infinite_cost.
(COST_SCALING_FACTOR_BOUND, determine_scaling_factor): New.
(tree_ssa_iv_optimize_loop): Call determine_scaling_factor. Extend
live range for array of loop's basic blocks. Cleanup aux field of
loop's basic blocks.
2018-05-05 Bin Cheng <bin.ch...@linux.alibaba.com>
PR tree-optimization/90240
* gfortran.dg/graphite/pr90240.f: New test.
0001-pr90240.patch
Description: Binary data
