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* [Bug tree-optimization/107247] New: SLP reduction results fail to reduce to a single accumulator
@ 2022-10-13 12:37 rguenth at gcc dot gnu.org
2022-10-13 12:59 ` [Bug tree-optimization/107247] " rguenth at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-10-13 12:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107247
Bug ID: 107247
Summary: SLP reduction results fail to reduce to a single
accumulator
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
Target Milestone: ---
float fl[128];
int x[128];
float
foo (int n1)
{
float sum0, sum1, sum2, sum3;
sum0 = sum1 = sum2 = sum3 = 0.0f;
int n = (n1 / 4) * 4;
for (int i = 0; i < n; i += 4)
{
sum0 += fabs (fl[i]);
sum1 += fabs (fl[i + 1]);
sum2 += fabs (fl[i + 2]);
sum3 += fabs (fl[i + 3]);
x[i] = 1;
}
return sum0 + sum1 + sum2 + sum3;
}
shows how we fail to reduce the SLP reduction accumulators to a single one
before extracting the elements:
<bb 3> [local count: 567644343]:
# sum0_37 = PHI <sum0_29(7), 0.0(9)>
# sum1_39 = PHI <sum1_30(7), 0.0(9)>
# sum2_41 = PHI <sum2_31(7), 0.0(9)>
# sum3_43 = PHI <sum3_32(7), 0.0(9)>
# i_45 = PHI <i_34(7), 0(9)>
# vectp_fl.8_89 = PHI <vectp_fl.8_90(7), &fl(9)>
# vect_sum3_43.15_102 = PHI <vect_sum3_32.16_106(7), { 0.0, 0.0, 0.0, 0.0
}(9)>
# vect_sum3_43.15_103 = PHI <vect_sum3_32.16_107(7), { 0.0, 0.0, 0.0, 0.0
}(9)>
# vect_sum3_43.15_104 = PHI <vect_sum3_32.16_108(7), { 0.0, 0.0, 0.0, 0.0
}(9)>
# vect_sum3_43.15_105 = PHI <vect_sum3_32.16_109(7), { 0.0, 0.0, 0.0, 0.0
}(9)>
...
vect__12.14_98 = ABS_EXPR <vect__11.10_91>;
vect__12.14_99 = ABS_EXPR <vect__11.11_93>;
vect__12.14_100 = ABS_EXPR <vect__11.12_95>;
vect__12.14_101 = ABS_EXPR <vect__11.13_97>;
vect_sum3_32.16_106 = vect__12.14_98 + vect_sum3_43.15_102;
vect_sum3_32.16_107 = vect__12.14_99 + vect_sum3_43.15_103;
vect_sum3_32.16_108 = vect__12.14_100 + vect_sum3_43.15_104;
vect_sum3_32.16_109 = vect__12.14_101 + vect_sum3_43.15_105;
...
<bb 11> [local count: 94607391]:
# sum0_48 = PHI <sum0_29(3)>
# sum1_36 = PHI <sum1_30(3)>
# sum2_35 = PHI <sum2_31(3)>
# sum3_24 = PHI <sum3_32(3)>
# vect_sum3_32.16_110 = PHI <vect_sum3_32.16_106(3)>
# vect_sum3_32.16_111 = PHI <vect_sum3_32.16_107(3)>
# vect_sum3_32.16_112 = PHI <vect_sum3_32.16_108(3)>
# vect_sum3_32.16_113 = PHI <vect_sum3_32.16_109(3)>
_114 = BIT_FIELD_REF <vect_sum3_32.16_110, 32, 0>;
_115 = BIT_FIELD_REF <vect_sum3_32.16_110, 32, 32>;
_116 = BIT_FIELD_REF <vect_sum3_32.16_110, 32, 64>;
_117 = BIT_FIELD_REF <vect_sum3_32.16_110, 32, 96>;
_118 = BIT_FIELD_REF <vect_sum3_32.16_111, 32, 0>;
_119 = BIT_FIELD_REF <vect_sum3_32.16_111, 32, 32>;
_120 = BIT_FIELD_REF <vect_sum3_32.16_111, 32, 64>;
_121 = BIT_FIELD_REF <vect_sum3_32.16_111, 32, 96>;
_122 = BIT_FIELD_REF <vect_sum3_32.16_112, 32, 0>;
_123 = BIT_FIELD_REF <vect_sum3_32.16_112, 32, 32>;
_124 = BIT_FIELD_REF <vect_sum3_32.16_112, 32, 64>;
_125 = BIT_FIELD_REF <vect_sum3_32.16_112, 32, 96>;
_126 = BIT_FIELD_REF <vect_sum3_32.16_113, 32, 0>;
_127 = BIT_FIELD_REF <vect_sum3_32.16_113, 32, 32>;
_128 = BIT_FIELD_REF <vect_sum3_32.16_113, 32, 64>;
_129 = BIT_FIELD_REF <vect_sum3_32.16_113, 32, 96>;
_130 = _114 + _118;
_131 = _115 + _119;
_132 = _116 + _120;
_133 = _117 + _121;
_134 = _130 + _122;
_135 = _131 + _123;
_136 = _132 + _124;
_137 = _133 + _125;
_138 = _134 + _126;
_139 = _135 + _127;
_140 = _136 + _128;
_141 = _137 + _129;
...
instead of doing vector adds and a single series of extracts.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/107247] SLP reduction results fail to reduce to a single accumulator
2022-10-13 12:37 [Bug tree-optimization/107247] New: SLP reduction results fail to reduce to a single accumulator rguenth at gcc dot gnu.org
@ 2022-10-13 12:59 ` rguenth at gcc dot gnu.org
2022-10-13 14:28 ` cvs-commit at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-10-13 12:59 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107247
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
Last reconfirmed| |2022-10-13
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
I have a patch.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/107247] SLP reduction results fail to reduce to a single accumulator
2022-10-13 12:37 [Bug tree-optimization/107247] New: SLP reduction results fail to reduce to a single accumulator rguenth at gcc dot gnu.org
2022-10-13 12:59 ` [Bug tree-optimization/107247] " rguenth at gcc dot gnu.org
@ 2022-10-13 14:28 ` cvs-commit at gcc dot gnu.org
2022-10-13 14:30 ` rguenth at gcc dot gnu.org
2023-12-12 3:17 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-10-13 14:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107247
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:
https://gcc.gnu.org/g:e5139d18dfb8130876ea59178e8471fb1b34bb80
commit r13-3276-ge5139d18dfb8130876ea59178e8471fb1b34bb80
Author: Richard Biener <rguenther@suse.de>
Date: Thu Oct 13 14:56:01 2022 +0200
tree-optimization/107247 - reduce SLP reduction accumulator
The following makes sure to reduce a multi-vector SLP reduction
accumulator to a single vector using vector operations if
easily possible (if the number of lanes in the vector type is
a multiple of the number of scalar accumulators).
PR tree-optimization/107247
* tree-vect-loop.cc (vect_create_epilog_for_reduction):
Reduce multi vector SLP reduction accumulators. Check
the adjusted number of accumulator vectors against
one for the re-use in the epilogue.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/107247] SLP reduction results fail to reduce to a single accumulator
2022-10-13 12:37 [Bug tree-optimization/107247] New: SLP reduction results fail to reduce to a single accumulator rguenth at gcc dot gnu.org
2022-10-13 12:59 ` [Bug tree-optimization/107247] " rguenth at gcc dot gnu.org
2022-10-13 14:28 ` cvs-commit at gcc dot gnu.org
@ 2022-10-13 14:30 ` rguenth at gcc dot gnu.org
2023-12-12 3:17 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-10-13 14:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107247
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
This is now fixed for the cases not requiring permutations. One could think of
a three-lane SLP reduction with three four component vectors being reduced
by first "expanding" to four "three component" vectors, summing them and then
extracting from the lower three lanes. Likewise for a six-lane SLP reduction
which would get a more complex extraction of two-vector, six-lane pairs.
Unless a compelling case comes along I don't consider these important.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/107247] SLP reduction results fail to reduce to a single accumulator
2022-10-13 12:37 [Bug tree-optimization/107247] New: SLP reduction results fail to reduce to a single accumulator rguenth at gcc dot gnu.org
` (2 preceding siblings ...)
2022-10-13 14:30 ` rguenth at gcc dot gnu.org
@ 2023-12-12 3:17 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-12-12 3:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107247
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |13.0
^ permalink raw reply [flat|nested] 5+ messages in thread
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2022-10-13 12:37 [Bug tree-optimization/107247] New: SLP reduction results fail to reduce to a single accumulator rguenth at gcc dot gnu.org
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2022-10-13 14:28 ` cvs-commit at gcc dot gnu.org
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