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From: "xxs_chy at outlook dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/113105] New: Missing optimzation: fold `div(v, a) * b + rem(v, a)` to `div(v, a) * (b - a) + v` Date: Thu, 21 Dec 2023 08:50:49 +0000 [thread overview] Message-ID: <bug-113105-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113105 Bug ID: 113105 Summary: Missing optimzation: fold `div(v, a) * b + rem(v, a)` to `div(v, a) * (b - a) + v` Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: xxs_chy at outlook dot com Target Milestone: --- Godbolt example: https://godbolt.org/z/b5va37Tzx For example: unsigned char _bin2bcd(unsigned val) { return ((val / 10) << 4) + val % 10; } can be folded to: unsigned char new_bin2bcd(unsigned val) { return val / 10 * 6 + val; } This C snippet is extracted from https://github.com/torvalds/linux/blob/master/lib/bcd.c Both GCC and LLVM missed it.
next reply other threads:[~2023-12-21 8:50 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-12-21 8:50 xxs_chy at outlook dot com [this message] 2023-12-21 16:06 ` [Bug tree-optimization/113105] " pinskia at gcc dot gnu.org 2023-12-21 16:09 ` jakub at gcc dot gnu.org 2023-12-21 17:16 ` xxs_chy at outlook dot com 2023-12-21 17:50 ` jakub at gcc dot gnu.org 2023-12-21 22:51 ` jakub at gcc dot gnu.org 2023-12-23 10:02 ` xxs_chy at outlook dot com 2024-05-30 4:46 ` pinskia at gcc dot gnu.org
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