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From: "user202729 at protonmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/115576] [14/15 regression] Worse code generated for simple struct conversion since r14-2386-gbdf2737cda53a8 Date: Wed, 26 Jun 2024 07:10:54 +0000 [thread overview] Message-ID: <bug-115576-4-kUFswnprGH@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-115576-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115576 --- Comment #5 from user202729 <user202729 at protonmail dot com> --- I think this can be resolved by implementing some code in combine.cc to replace: (set:TI (reg:TI 101) (zero_extend:TI (...:DI ...))) (set:DI (reg:DI ...) (subreg:DI (reg:TI 101) 8)) with (set:TI (reg:TI 101) (zero_extend:TI (...:DI ...))) (set:DI (reg:DI ...) (const_int 0)) This certainly is always an improvement, because 0 is simpler than extracting the subregister. After that, a few other passes of combine rescanning should be able to constant fold the 0 forward. Unfortunately, I don't know how to modify combine.cc or some other files to handle this pattern. Can anyone give a suggestion? (maybe add a define_peephole2 in common.md ? )
prev parent reply other threads:[~2024-06-26 7:10 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-06-21 7:44 [Bug rtl-optimization/115576] New: [14 regression] Worse code generated for simple struct conversion jzwinck at gmail dot com 2024-06-21 7:49 ` [Bug c++/115576] " pinskia at gcc dot gnu.org 2024-06-21 7:52 ` [Bug c++/115576] [14/15 " rguenth at gcc dot gnu.org 2024-06-21 17:44 ` [Bug target/115576] " pinskia at gcc dot gnu.org 2024-06-25 8:17 ` user202729 at protonmail dot com 2024-06-26 7:10 ` user202729 at protonmail dot com [this message]
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