Richard Biener <richard.guent...@gmail.com> writes:
> On Thu, May 24, 2018 at 10:31 AM Jakub Jelinek <ja...@redhat.com> wrote:
>> On Thu, May 24, 2018 at 09:21:35AM +0100, Richard Sandiford wrote:
>> > vect_recog_divmod_pattern currently bails out if the target has
>> > native support for integer division, but I think in practice
>> > it's always going to be better to open-code it anyway, just as
>> > we usually open-code scalar divisions by constants.
>> >
>> > I think the only currently affected target is MIPS MSA, where for:
>
>> Isn't powerpcspe affected too? It has a divv2si3 pattern.
Ah, yeah. I forgot to update the description after you mentioned
that on IRC, sorry.
>> > --- gcc/tree-vect-patterns.c 2018-05-16 12:48:59.115202362 +0100
>> > +++ gcc/tree-vect-patterns.c 2018-05-24 09:18:10.445466941 +0100
>> > @@ -2639,7 +2639,6 @@ vect_recog_divmod_pattern (vec<gimple *>
>> > enum tree_code rhs_code;
>> > stmt_vec_info stmt_vinfo = vinfo_for_stmt (last_stmt);
>> > vec_info *vinfo = stmt_vinfo->vinfo;
>> > - optab optab;
>> > tree q;
>> > int dummy_int, prec;
>> > stmt_vec_info def_stmt_vinfo;
>> > @@ -2674,17 +2673,6 @@ vect_recog_divmod_pattern (vec<gimple *>
>> > if (vectype == NULL_TREE)
>> > return NULL;
>> >
>> > - /* If the target can handle vectorized division or modulo natively,
>> > - don't attempt to optimize this. */
>> > - optab = optab_for_tree_code (rhs_code, vectype, optab_default);
>> > - if (optab != unknown_optab)
>> > - {
>> > - machine_mode vec_mode = TYPE_MODE (vectype);
>> > - int icode = (int) optab_handler (optab, vec_mode);
>> > - if (icode != CODE_FOR_nothing)
>> > - return NULL;
>> > - }
>> > -
>
>> Shouldn't we instead keep it, but only do it if
>> optimize_bb_for_size_p (gimple_bb (last_stmt)) ?
>> I mean, a hw division is very likely shorter than what we replace it
> with...
>
> Good idea. While loops are checked for optimize_loop_nest_for_speed if
> not forced vect BB vectorization has no such predicate.
Like this, if it passes testing?
Thanks,
Richard
2018-05-24 Richard Sandiford <richard.sandif...@linaro.org>
gcc/
* tree-vect-patterns.c: Include predict.h.
(vect_recog_divmod_pattern): Restrict check for division support
to when optimizing for size.
gcc/testsuite/
* gcc.dg/vect/bb-slp-div-1.c: New XFAILed test.
Index: gcc/tree-vect-patterns.c
===================================================================
*** gcc/tree-vect-patterns.c 2018-05-24 13:50:21.656138942 +0100
--- gcc/tree-vect-patterns.c 2018-05-24 13:50:21.819134113 +0100
*************** vect_recog_divmod_pattern (vec<gimple *>
*** 2674,2688 ****
if (vectype == NULL_TREE)
return NULL;
! /* If the target can handle vectorized division or modulo natively,
! don't attempt to optimize this. */
! optab = optab_for_tree_code (rhs_code, vectype, optab_default);
! if (optab != unknown_optab)
{
! machine_mode vec_mode = TYPE_MODE (vectype);
! int icode = (int) optab_handler (optab, vec_mode);
! if (icode != CODE_FOR_nothing)
! return NULL;
}
prec = TYPE_PRECISION (itype);
--- 2674,2692 ----
if (vectype == NULL_TREE)
return NULL;
! if (optimize_bb_for_size_p (gimple_bb (last_stmt)))
{
! /* If the target can handle vectorized division or modulo natively,
! don't attempt to optimize this, since native division is likely
! to give smaller code. */
! optab = optab_for_tree_code (rhs_code, vectype, optab_default);
! if (optab != unknown_optab)
! {
! machine_mode vec_mode = TYPE_MODE (vectype);
! int icode = (int) optab_handler (optab, vec_mode);
! if (icode != CODE_FOR_nothing)
! return NULL;
! }
}
prec = TYPE_PRECISION (itype);
Index: gcc/testsuite/gcc.dg/vect/bb-slp-div-1.c
===================================================================
*** /dev/null 2018-04-20 16:19:46.369131350 +0100
--- gcc/testsuite/gcc.dg/vect/bb-slp-div-1.c 2018-05-24 13:50:21.818134143
+0100
***************
*** 0 ****
--- 1,19 ----
+ /* { dg-do compile } */
+ /* { dg-additional-options "-msve-vector-bits=256" { target aarch64_sve } } */
+
+ int x[8];
+
+ void
+ f (void)
+ {
+ x[0] /= 2;
+ x[1] /= 3;
+ x[2] /= 4;
+ x[3] /= 5;
+ x[4] /= 6;
+ x[5] /= 7;
+ x[6] /= 8;
+ x[7] /= 9;
+ }
+
+ /* { dg-final { scan-tree-dump "basic block vectorized" "slp2" { xfail *-*-*
} } } */
