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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/106902] [11/12/13/14 Regression] Program compiled with -O3 -mfma produces different result Date: Fri, 12 May 2023 06:27:26 +0000 [thread overview] Message-ID: <bug-106902-4-kfTqQ346w5@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-106902-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106902 --- Comment #21 from Richard Biener <rguenth at gcc dot gnu.org> --- (In reply to Alexander Monakov from comment #20) > I missed it the first time around, but placing PAREN_EXPR around the > complete expression won't work: nothing will prevent GCC from duplicating > evaluations of the sub-expressions, and then randomly forming FMAs like > here. It would just bury this class of bugs deeper. Hmm, true. > Now that we are in stage1, can we make some kind of progress here? Is there > any buy-in for: > > 1. Implementing fp-contract=on via GENERIC folding? > 2. Defaulting to fp-contract=on instead of fp-contract=fast under -std=gnu*? > 3. Enabling fp-contract=fast under -ffast-math? Sounds reasonable. Though I wouldn't use GENERIC folding but instead some folding-like code in c-family/ that for example would get invoked by genericization or via the gimplification hook? If we'd add GENERIC folding in fold-const.cc or match.pd the chance is that it will pick up FMAs "late".
next prev parent reply other threads:[~2023-05-12 6:27 UTC|newest] Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-09-10 18:58 [Bug tree-optimization/106902] New: Program compiled with -O3 -fmfa " jhllawrence963 at gmail dot com 2022-09-10 19:07 ` [Bug target/106902] Program compiled with -O3 -mfma " pinskia at gcc dot gnu.org 2022-09-12 8:01 ` [Bug target/106902] [11/12/13 Regression] " rguenth at gcc dot gnu.org 2022-09-12 14:08 ` marxin at gcc dot gnu.org 2022-09-12 14:10 ` [Bug target/106902] [11/12 " marxin at gcc dot gnu.org 2022-09-13 7:06 ` [Bug target/106902] [11/12/13 " rguenth at gcc dot gnu.org 2022-09-14 15:20 ` amonakov at gcc dot gnu.org 2022-09-15 9:33 ` amonakov at gcc dot gnu.org 2022-09-17 18:19 ` jhllawrence963 at gmail dot com 2022-09-17 18:23 ` jhllawrence963 at gmail dot com 2022-09-19 7:08 ` rguenth at gcc dot gnu.org 2022-09-19 7:14 ` amonakov at gcc dot gnu.org 2022-09-19 7:25 ` rguenth at gcc dot gnu.org 2022-09-19 8:14 ` amonakov at gcc dot gnu.org 2022-09-19 9:44 ` rguenth at gcc dot gnu.org 2022-09-27 18:31 ` amonakov at gcc dot gnu.org 2022-09-29 6:41 ` rguenth at gcc dot gnu.org 2022-09-29 11:28 ` amonakov at gcc dot gnu.org 2022-09-29 13:39 ` rguenther at suse dot de 2022-09-30 6:17 ` amonakov at gcc dot gnu.org 2023-05-11 17:32 ` [Bug target/106902] [11/12/13/14 " amonakov at gcc dot gnu.org 2023-05-12 6:27 ` rguenth at gcc dot gnu.org [this message] 2023-05-17 18:49 ` amonakov at gcc dot gnu.org 2023-05-17 18:54 ` pinskia at gcc dot gnu.org 2023-05-18 5:53 ` rguenth at gcc dot gnu.org 2023-05-18 8:31 ` amonakov at gcc dot gnu.org 2023-05-18 16:03 ` amonakov at gcc dot gnu.org 2023-05-18 16:52 ` rguenther at suse dot de 2023-05-29 10:07 ` jakub at gcc dot gnu.org
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