On Sun, May 5, 2019 at 8:03 AM bin.cheng <bin.ch...@linux.alibaba.com> wrote:
>
> > ------------------------------------------------------------------
> > Sender:Jakub Jelinek <ja...@redhat.com>
> > Sent At:2019 Apr. 17 (Wed.) 19:27
> > Recipient:Bin.Cheng <amker.ch...@gmail.com>
> > Cc:bin.cheng <bin.ch...@linux.alibaba.com>; GCC Patches
> > <gcc-patches@gcc.gnu.org>
> > Subject:Re: [PATCH PR90078]Capping comp_cost computation in ivopts
> >
> >
> > On Wed, Apr 17, 2019 at 07:14:05PM +0800, Bin.Cheng wrote:
> > > > As
> > > > #define INFTY 10000000
> > > > what is the reason to keep the previous condition as well?
> > > > I mean, if cost1.cost == INFTY or cost2.cost == INFTY,
> > > > cost1.cost + cost2.cost >= INFTY too.
> > > > Unless costs can go negative.
> > > It's a bit complicated, but in general, costs can go negative.
> >
> > Ok, no objections from me then (but as I don't know anything about it,
> > not an ack either; you are ivopts maintainer, so you don't need one).
>
> Hi,
> The previous patch was reverted on GCC-9 because of PR90240. PR90240 is now
> fixed by another patch. This is the updated patch for PR90078. It promotes
> type
> of ivopts cost from int to int64_t, as well as change behavior of
> infinite_cost overflow
> from saturation to assert.
> Please note, implicit conversions are kept in cost computation as before
> without
> introducing any narrowing.
>
> Bootstrap/test on x86_64 along with PR90240 patch. Is it OK?
Do not include system headers in .c files, instead those need to be
(and are already)
included via system.h.
/* The infinite cost. */
-#define INFTY 10000000
+#define INFTY 1000000000L
do we actually need this? What happens on a ilp32 host? That is, I believe
you can drop the 'L' (it fits into an int anyways)
@@ -256,6 +259,7 @@ operator- (comp_cost cost1, comp_cost cost2)
return infinite_cost;
gcc_assert (!cost2.infinite_cost_p ());
+ gcc_assert (cost1.cost - cost2.cost < infinite_cost.cost);
cost1.cost -= cost2.cost;
cost1.complexity -= cost2.complexity;
probably a pre-existing issue, but we do not seem to handle underflow
here in general, nor check that underflow doesn't get us below -INFTY.
I guess we really don't want negative costs? That doesn't seem to be
documented and I was also wondering why the cost isn't unsigned...
@@ -638,7 +646,7 @@ struct iv_ca
comp_cost cand_use_cost;
/* Total cost of candidates. */
- unsigned cand_cost;
+ int64_t cand_cost;
/* Number of times each invariant variable is used. */
unsigned *n_inv_var_uses;
shows this "issue". Can't we use uint64_t throughout the patch?
Otherwise this looks OK.
Thanks,
Richard.
> Thanks,
> bin
> 2019-05-05 Bin Cheng <bin.ch...@linux.alibaba.com>
>
> PR tree-optimization/90078
> * tree-ssa-loop-ivopts.c (inttypes.h): Include new header file.
> (INFTY): Increase the value for infinite cost.
> (struct comp_cost): Promote type of members to int64_t.
> (infinite_cost): Don't set complexity in initialization.
> (comp_cost::operator +,-,+=,-+,/=,*=): Assert when cost computation
> overflows to infinite_cost.
> (adjust_setup_cost): Promote type of parameter and cost computation
> to int64_t.
> (struct ainc_cost_data, struct iv_ca): Promote type of member to
> int64_t.
> (get_scaled_computation_cost_at, determine_iv_cost): Promote type of
> cost computation to int64_t.
> (determine_group_iv_costs, iv_ca_dump, find_optimal_iv_set): Use
> int64_t's format specifier in dump.
>
> 2018-05-05 Bin Cheng <bin.ch...@linux.alibaba.com>
>
> PR tree-optimization/90078
> * g++.dg/tree-ssa/pr90078.C: New test.
