On Thu, 3 Dec 2020, Prathamesh Kulkarni wrote:
> On Tue, 1 Dec 2020 at 16:39, Richard Biener <rguent...@suse.de> wrote:
> >
> > On Tue, 1 Dec 2020, Prathamesh Kulkarni wrote:
> >
> > > Hi,
> > > For the test mentioned in PR, I was trying to see if we could do
> > > specialized expansion for vcond in target when operands are -1 and 0.
> > > arm_expand_vcond gets the following operands:
> > > (reg:V8QI 113 [ _2 ])
> > > (reg:V8QI 117)
> > > (reg:V8QI 118)
> > > (lt (reg/v:V8QI 115 [ a ])
> > > (reg/v:V8QI 116 [ b ]))
> > > (reg/v:V8QI 115 [ a ])
> > > (reg/v:V8QI 116 [ b ])
> > >
> > > where r117 and r118 are set to vector constants -1 and 0 respectively.
> > > However, I am not sure if there's a way to check if the register is
> > > constant during expansion time (since we don't have df analysis yet) ?
> > >
> > > Alternatively, should we add a target hook that returns true if the
> > > result of vector comparison is set to all-ones or all-zeros, and then
> > > use this hook in gimple ISEL to effectively turn VEC_COND_EXPR into nop ?
> >
> > Would everything match-up for a .VEC_CMP IFN producing a non-mask
> > vector type? ISEL could special case the a ? -1 : 0 case this way.
> I think the vec_cmp pattern matches but it produces a masked vector type.
> In the attached patch, I simply replaced:
> _1 = a < b
> x = _1 ? -1 : 0
> with
> x = view_convert_expr<_1>
>
> For the test-case, isel generates:
> vector(8) <signed-boolean:8> _1;
> vector(8) signed char _2;
> uint8x8_t _5;
>
> <bb 2> [local count: 1073741824]:
> _1 = a_3(D) < b_4(D);
> _2 = VIEW_CONVERT_EXPR<vector(8) signed char>(_1);
> _5 = VIEW_CONVERT_EXPR<uint8x8_t>(_2);
> return _5;
>
> and results in desired code-gen:
> f1:
> vcgt.s8 d0, d1, d0
> bx lr
>
> Altho I guess, we should remove the redundant conversions during isel itself ?
> and result in:
> _1 = a_3(D) < b_4(D)
> _5 = VIEW_CONVERT_EXPR<uint8x8_t>(_1)
>
> (Patch is lightly tested with only vect.exp)
+ /* For targets where result of comparison is all-ones or all-zeros,
+ a < b ? -1 : 0 can be reduced to a < b. */
+
+ if (integer_minus_onep (op1) && integer_zerop (op2))
+ {
So this really belongs here:
tree op0_type = TREE_TYPE (op0);
tree op0a_type = TREE_TYPE (op0a);
<---
if (used_vec_cond_exprs >= 2
&& (get_vcond_mask_icode (mode, TYPE_MODE (op0_type))
!= CODE_FOR_nothing)
&& expand_vec_cmp_expr_p (op0a_type, op0_type, tcode))
{
+ gassign *def_stmt = dyn_cast<gassign *> (SSA_NAME_DEF_STMT (op0));
+ tree op0a = gimple_assign_rhs1 (def_stmt);
+ tree op0_type = TREE_TYPE (op0);
+ tree op0a_type = TREE_TYPE (op0a);
+ enum tree_code tcode = gimple_assign_rhs_code (def_stmt);
+
+ if (expand_vec_cmp_expr_p (op0a_type, op0_type, tcode))
+ {
+ tree conv_op = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (lhs), op0);
+ gassign *new_stmt = gimple_build_assign (lhs, conv_op);
+ gsi_replace (gsi, new_stmt, true);
and you need to verify that the mode of the lhs and the mode of op0
agree and that the target can actually expand_vec_cmp_expr_p
Richard.
> Thanks,
> Prathamesh
> >
> > > Thanks,
> > > Prathamesh
> > >
> >
> > --
> > Richard Biener <rguent...@suse.de>
> > SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
> > Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
