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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/107160] [13 regression] r13-2641-g0ee1548d96884d causes verification failure in spec2006
Date: Thu, 13 Oct 2022 12:05:31 +0000 [thread overview]
Message-ID: <bug-107160-4-TxSh4BD3wA@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-107160-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107160
--- Comment #14 from Richard Biener <rguenth at gcc dot gnu.org> ---
Aha, so the issue is that we have a vectorized epilogue here and the epilogue
of _that_ ends up doing
<bb 11> [local count: 94607391]:
# sum0_48 = PHI <sum0_28(3)>
# sum1_47 = PHI <sum1_29(3)>
# sum2_46 = PHI <sum2_30(3)>
# sum3_45 = PHI <sum3_31(3)>
# vect_sum3_31.16_101 = PHI <vect_sum3_31.16_97(3)>
# vect_sum3_31.16_102 = PHI <vect_sum3_31.16_98(3)>
# vect_sum3_31.16_103 = PHI <vect_sum3_31.16_99(3)>
# vect_sum3_31.16_104 = PHI <vect_sum3_31.16_100(3)>
_105 = BIT_FIELD_REF <vect_sum3_31.16_101, 32, 0>;
_106 = BIT_FIELD_REF <vect_sum3_31.16_101, 32, 32>;
...
this is from the main vect
<bb 17> [local count: 81467476]:
# sum0_135 = PHI <sum0_62(12)>
# sum1_136 = PHI <sum1_58(12)>
# sum2_137 = PHI <sum2_54(12)>
# sum3_138 = PHI <sum3_50(12)>
# vect_sum3_50.25_159 = PHI <vect_sum3_50.25_158(12)>
this is from the epilogue
<bb 15> [local count: 105119324]:
# sum0_15 = PHI <sum0_135(17), _129(11)>
# sum1_77 = PHI <sum1_136(17), _130(11)>
# sum2_75 = PHI <sum2_137(17), _131(11)>
# sum3_13 = PHI <sum3_138(17), _132(11)>
# _160 = PHI <vect_sum3_50.25_159(17), vect_sum3_31.16_101(11)>
_161 = BIT_FIELD_REF <_160, 32, 0>;
_162 = BIT_FIELD_REF <_160, 32, 32>;
_163 = BIT_FIELD_REF <_160, 32, 64>;
_164 = BIT_FIELD_REF <_160, 32, 96>;
_74 = _161 + _162;
_76 = _74 + _163;
_78 = _76 + _164;
so we fail to accumulate the main loops accumulators and just
use the first one. On x86 the vectorized epilogue uses a smaller
vector size but the same number of accumulators.
It seems it's simply unexpected to have the unrolled SLP reduction
and a vectorized epilogue with the same vector mode (but not unrolled).
I can reproduce the failure when patching the x86 cost model to force
unrolling by 2 (maybe we want a --param to force that to aid debugging...).
next prev parent reply other threads:[~2022-10-13 12:05 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-05 16:21 [Bug target/107160] New: " seurer at gcc dot gnu.org
2022-10-06 10:43 ` [Bug target/107160] " rguenth at gcc dot gnu.org
2022-10-06 14:04 ` seurer at gcc dot gnu.org
2022-10-06 19:08 ` seurer at gcc dot gnu.org
2022-10-10 2:29 ` linkw at gcc dot gnu.org
2022-10-10 19:14 ` seurer at gcc dot gnu.org
2022-10-12 8:31 ` linkw at gcc dot gnu.org
2022-10-13 9:57 ` linkw at gcc dot gnu.org
2022-10-13 10:16 ` rguenth at gcc dot gnu.org
2022-10-13 10:31 ` linkw at gcc dot gnu.org
2022-10-13 11:05 ` rguenther at suse dot de
2022-10-13 11:45 ` linkw at gcc dot gnu.org
2022-10-13 11:50 ` rguenther at suse dot de
2022-10-13 12:01 ` marxin at gcc dot gnu.org
2022-10-13 12:05 ` rguenth at gcc dot gnu.org [this message]
2022-10-13 12:23 ` rguenth at gcc dot gnu.org
2022-10-13 13:17 ` cvs-commit at gcc dot gnu.org
2022-10-13 13:19 ` [Bug target/107160] [12/13 " rguenth at gcc dot gnu.org
2022-10-14 2:54 ` [Bug target/107160] [12 " linkw at gcc dot gnu.org
2022-10-17 13:10 ` cvs-commit at gcc dot gnu.org
2022-10-17 13:11 ` rguenth at gcc dot gnu.org
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