On Fri, 4 Dec 2020 at 17:18, Richard Biener <rguent...@suse.de> wrote:
>
> On Fri, 4 Dec 2020, Prathamesh Kulkarni wrote:
>
> > On Thu, 3 Dec 2020 at 16:35, Richard Biener <rguent...@suse.de> wrote:
> > >
> > > 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
> > Thanks for the suggestions, does the attached patch look OK ?
> > Sorry, I am not sure how to check if target can actually expand vec_cmp ?
> > I assume that since expand_vec_cmp_expr_p queries optab and if it gets
> > a valid cmp icode, that
> > should be sufficient ?
>
> Yes
Hi Richard,
I tested the patch, and it shows one regression for pr78102.c, because
of extra pcmpeqq in code-gen for x != y on x86.
For the test-case:
__v2di
baz (const __v2di x, const __v2di y)
{
return x != y;
}
Before patch:
baz:
pcmpeqq %xmm1, %xmm0
pcmpeqd %xmm1, %xmm1
pandn %xmm1, %xmm0
ret
After patch,
Before ISEL:
vector(2) <signed-boolean:64> _1;
__v2di _4;
<bb 2> [local count: 1073741824]:
_1 = x_2(D) != y_3(D);
_4 = VEC_COND_EXPR <_1, { -1, -1 }, { 0, 0 }>;
return _4;
After ISEL:
vector(2) <signed-boolean:64> _1;
__v2di _4;
<bb 2> [local count: 1073741824]:
_1 = x_2(D) != y_3(D);
_4 = VIEW_CONVERT_EXPR<__v2di>(_1);
return _4;
which results in:
pcmpeqq %xmm1, %xmm0
pxor %xmm1, %xmm1
pcmpeqq %xmm1, %xmm0
ret
IIUC, the new code-gen is essentially comparing two args for equality, and then
comparing the result against zero to invert it, so it looks correct ?
I am not sure which of the above two sequences is better tho ?
If the new code-gen is OK, would it be OK to adjust the test-case ?
Thanks,
Prathamesh
>
> > Thanks,
> > Prathamesh
> > >
> > > 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)
> >
>
> --
> Richard Biener <rguent...@suse.de>
> SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
> Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
pr97872-2.diff
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