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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/102124] [11/12 Regression] -ftree-loop-vectorize Causing Data To Lose Sign Bit on AARCH64 Platform
Date: Mon, 30 Aug 2021 08:44:55 +0000 [thread overview]
Message-ID: <bug-102124-4-fJwIgQrTRZ@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-102124-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102124
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Before vectorization the loop body is:
_1 = a_19(D) + i_29;
_2 = *_1;
_3 = (int) _2;
_4 = b_20(D) + i_29;
_5 = *_4;
_6 = (int) _5;
_7 = _3 - _6;
ab_21 = _7 | ab_25;
_10 = _6 - _3;
ba_22 = _10 | ba_27;
where _2 and _5 are unsigned char and _3, _6, _7, _10 are int.
It is vectorized as
vect_patt_54.17_61 = WIDEN_MINUS_LO_EXPR <vect__2.13_56, vect__5.16_17>;
vect_patt_54.17_62 = WIDEN_MINUS_HI_EXPR <vect__2.13_56, vect__5.16_17>;
vect_patt_53.18_63 = [vec_unpack_lo_expr] vect_patt_54.17_61;
vect_patt_53.18_64 = [vec_unpack_hi_expr] vect_patt_54.17_61;
vect_patt_53.18_65 = [vec_unpack_lo_expr] vect_patt_54.17_62;
vect_patt_53.18_66 = [vec_unpack_hi_expr] vect_patt_54.17_62;
_7 = _3 - _6;
vect_ab_21.19_67 = vect_patt_53.18_63 | vect_ab_25.9_13;
vect_ab_21.19_68 = vect_patt_53.18_64 | vect_ab_21.19_67;
vect_ab_21.19_69 = vect_patt_53.18_65 | vect_ab_21.19_68;
vect_ab_21.19_70 = vect_patt_53.18_66 | vect_ab_21.19_69;
ab_21 = _7 | ab_25;
which means it is vectorized as if it was instead of (int) _2 - (int) _6
(int) (unsigned short) ((unsigned short) _2 - (unsigned short) _6).
next prev parent reply other threads:[~2021-08-30 8:44 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-30 8:07 [Bug c/102124] New: GCC 11.2.1 -ftree-loop-vectorize Causing Data To Lose Sign Bit changyp6 at gmail dot com
2021-08-30 8:11 ` [Bug c/102124] " changyp6 at gmail dot com
2021-08-30 8:32 ` [Bug target/102124] [11/12 Regression] -ftree-loop-vectorize Causing Data To Lose Sign Bit on AARCH64 Platform jakub at gcc dot gnu.org
2021-08-30 8:44 ` jakub at gcc dot gnu.org [this message]
2021-08-30 9:28 ` changyp6 at gmail dot com
2021-08-30 10:05 ` jakub at gcc dot gnu.org
2021-08-30 10:07 ` [Bug tree-optimization/102124] " jakub at gcc dot gnu.org
2021-08-30 10:15 ` jakub at gcc dot gnu.org
2021-09-01 4:19 ` changyp6 at gmail dot com
2021-09-01 11:40 ` cvs-commit at gcc dot gnu.org
2021-09-01 11:41 ` cvs-commit at gcc dot gnu.org
2021-09-01 11:48 ` jakub at gcc dot gnu.org
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