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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/96793] __builtin_floor produces wrong result when rounding direction is FE_DOWNWARD Date: Wed, 23 Dec 2020 08:21:03 +0000 [thread overview] Message-ID: <bug-96793-4-0btzVw7KPK@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-96793-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96793 --- Comment #22 from Uroš Bizjak <ubizjak at gmail dot com> --- https://gcc.gnu.org/g:edb28850520d1137d12a1cc1c0e89c11e6b0c6ef commit r8-10691-gedb28850520d1137d12a1cc1c0e89c11e6b0c6ef Author: Uros Bizjak <ubizjak@gmail.com> Date: Wed Dec 23 09:18:12 2020 +0100 i386: Fix __builtin_floor with FE_DOWNWARD rounding direction [PR96793] x86_expand_floorceil expander uses x86_sse_copysign_to_positive, which is unable to change the sign from - to +. When FE_DOWNWARD rounding direction is in effect, the expanded sequence that involves subtraction can trigger x - x = -0.0 special rule. x86_sse_copysign_to_positive fails to change the sign of the intermediate value, assumed to always be positive, back to positive. The patch adds one extra fabs that strips the sign from the intermediate value when flag_rounding_math is in effect. 2020-12-22 Uroš Bizjak <ubizjak@gmail.com> gcc/ PR target/96793 * config/i386/i386.c (ix86_expand_floorceil): Remove the sign of the intermediate value for flag_rounding_math. (ix86_expand_floorceildf_32): Ditto. gcc/testsuite/ PR target/96793 * gcc.target/i386/pr96793.c: New test.
next prev parent reply other threads:[~2020-12-23 8:21 UTC|newest] Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-08-26 9:10 [Bug c/96793] New: " chfast at gmail dot com 2020-08-26 9:11 ` [Bug c/96793] " chfast at gmail dot com 2020-08-26 9:11 ` chfast at gmail dot com 2020-08-26 9:12 ` chfast at gmail dot com 2020-08-26 9:21 ` chfast at gmail dot com 2020-08-26 10:46 ` [Bug target/96793] " rguenth at gcc dot gnu.org 2020-08-26 11:17 ` ubizjak at gmail dot com 2020-08-28 7:26 ` ubizjak at gmail dot com 2020-08-28 7:26 ` ubizjak at gmail dot com 2020-08-28 8:58 ` chfast at gmail dot com 2020-08-28 9:00 ` ubizjak at gmail dot com 2020-08-28 9:40 ` rguenth at gcc dot gnu.org 2020-08-28 9:48 ` ubizjak at gmail dot com 2020-08-28 9:54 ` ubizjak at gmail dot com 2020-08-28 11:31 ` glisse at gcc dot gnu.org 2020-08-28 12:20 ` glisse at gcc dot gnu.org 2020-08-28 14:06 ` chfast at gmail dot com 2020-08-28 14:31 ` chfast at gmail dot com 2020-08-28 14:37 ` ubizjak at gmail dot com 2020-12-22 12:17 ` ubizjak at gmail dot com 2020-12-22 17:20 ` ubizjak at gmail dot com 2020-12-22 20:13 ` ubizjak at gmail dot com 2020-12-23 8:20 ` ubizjak at gmail dot com 2020-12-23 8:21 ` ubizjak at gmail dot com [this message] 2020-12-23 8:21 ` ubizjak at gmail dot com
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