On Mon, 7 Dec 2020 at 13:01, Richard Biener <[email protected]> wrote:
>
> On Mon, 7 Dec 2020, Prathamesh Kulkarni wrote:
>
> > On Fri, 4 Dec 2020 at 17:18, Richard Biener <[email protected]> wrote:
> > >
> > > On Fri, 4 Dec 2020, Prathamesh Kulkarni wrote:
> > >
> > > > On Thu, 3 Dec 2020 at 16:35, Richard Biener <[email protected]> wrote:
> > > > >
> > > > > On Thu, 3 Dec 2020, Prathamesh Kulkarni wrote:
> > > > >
> > > > > > On Tue, 1 Dec 2020 at 16:39, Richard Biener <[email protected]>
> > > > > > 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 ?
>
> In case pcmpeqq is double-issue the first variant might be faster while
> the second variant has the advantage of the "free" pxor, but back-to-back
> pcmpeqq might have an issue.
>
> I think on GIMPLE the new code is preferable and adjustments are
> target business. I wouldn't be surprised if the x86 backend
> special-cases vcond to {-1,-1}, {0,0} already to arrive at the first
> variant.
>
> Did you check how
>
> a = x != y ? { -1, -1 } : {0, 0 };
> b = x != y ? { 1, 2 } : { 3, 4 };
>
> is handled before/after your patch? That is, make the comparison
> CSEd between two VEC_COND_EXPRs?
For the test-case:
__v2di f(__v2di, __v2di);
__v2di
baz (const __v2di x, const __v2di y)
{
__v2di a = (x != y);
__v2di b = (x != y) ? (__v2di) {1, 2} : (__v2di) {3, 4};
return f (a, b);
}
Before patch, isel converts both to .vcondeq:
__v2di b;
__v2di a;
__v2di _8;
<bb 2> [local count: 1073741824]:
a_4 = .VCONDEQ (x_2(D), y_3(D), { -1, -1 }, { 0, 0 }, 114);
b_5 = .VCONDEQ (x_2(D), y_3(D), { 1, 2 }, { 3, 4 }, 114);
_8 = f (a_4, b_5); [tail call]
return _8;
and results in following code-gen:
_Z3bazDv2_xS_:
.LFB5666:
pcmpeqq %xmm1, %xmm0
pcmpeqd %xmm1, %xmm1
movdqa %xmm0, %xmm2
pandn %xmm1, %xmm2
movdqa .LC0(%rip), %xmm1
pblendvb %xmm0, .LC1(%rip), %xmm1
movdqa %xmm2, %xmm0
jmp _Z1fDv2_xS_
With patch, isel converts a = (x != y) ? {-1, -1} : {0, 0} to
view_convert_expr and the other
to vcondeq:
__v2di b;
__v2di a;
vector(2) <signed-boolean:64> _1;
__v2di _8;
<bb 2> [local count: 1073741824]:
_1 = x_2(D) != y_3(D);
a_4 = VIEW_CONVERT_EXPR<__v2di>(_1);
b_5 = .VCONDEQ (x_2(D), y_3(D), { 1, 2 }, { 3, 4 }, 114);
_8 = f (a_4, b_5); [tail call]
return _8;
which results in following code-gen:
_Z3bazDv2_xS_:
.LFB5666:
pcmpeqq %xmm1, %xmm0
pxor %xmm2, %xmm2
movdqa .LC0(%rip), %xmm1
pblendvb %xmm0, .LC1(%rip), %xmm1
pcmpeqq %xmm0, %xmm2
movdqa %xmm2, %xmm0
jmp _Z1fDv2_xS_
Thanks,
Prathamesh
>
> Thanks,
> Richard.
>
>
> > Thanks,
> > Prathamesh
> > >
> > > > Thanks,
> > > > Prathamesh
> > > > >
> > > > > Richard.
> > > > >
> > > > >
> > > > >
> > > > > > Thanks,
> > > > > > Prathamesh
> > > > > > >
> > > > > > > > Thanks,
> > > > > > > > Prathamesh
> > > > > > > >
> > > > > > >
> > > > > > > --
> > > > > > > Richard Biener <[email protected]>
> > > > > > > SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409
> > > > > > > Nuernberg,
> > > > > > > Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
> > > > > >
> > > > >
> > > > > --
> > > > > Richard Biener <[email protected]>
> > > > > SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409
> > > > > Nuernberg,
> > > > > Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
> > > >
> > >
> > > --
> > > Richard Biener <[email protected]>
> > > SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
> > > Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
> >
>
> --
> Richard Biener <[email protected]>
> SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
> Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
