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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/110992] [13/14 Regression] missed VRP optimization due to transformation of `a & -zero_one_valued_p` into `a * zero_one_valued_p` Date: Fri, 15 Sep 2023 03:19:01 +0000 [thread overview] Message-ID: <bug-110992-4-8xzMIgzQJp@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-110992-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110992 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Target Milestone|14.0 |13.3 Summary|[14 Regression] Dead Code |[13/14 Regression] missed |Elimination Regression at |VRP optimization due to |-O3 since |transformation of `a & |r14-1654-g7ceed7e3e29 |-zero_one_valued_p` into `a | |* zero_one_valued_p` --- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Hmm, I think this is a ranger issue really. Take: ``` int f(unsigned b, short c) { int bt = b; int bt1 = bt; int t = bt1 & -(c!=0); // int t = bt1 * (c!=0); if (!t) return 0; foo(bt == 0); return 0; } ``` That `bt == 0` should be figured out that is 0 there. We could figure that out in GCC 12 even. But in GCC 13+ we could not. That is traced back to r13-793-g8fb94fc6097c but really the ranger should figure out if you have a*b != 0, then both a and b should be non-zero ... But currently that is not support .... It looks like we only handle `a & b` that way ...
next prev parent reply other threads:[~2023-09-15 3:19 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-08-11 13:24 [Bug tree-optimization/110992] New: [14 Regression] Dead Code Elimination Regression at -O3 since r14-1654-g7ceed7e3e29 scherrer.sv at gmail dot com 2023-08-11 17:38 ` [Bug tree-optimization/110992] " pinskia at gcc dot gnu.org 2023-08-26 0:30 ` pinskia at gcc dot gnu.org 2023-09-14 21:11 ` pinskia at gcc dot gnu.org 2023-09-14 21:22 ` pinskia at gcc dot gnu.org 2023-09-15 3:19 ` pinskia at gcc dot gnu.org [this message] 2023-09-15 3:54 ` [Bug tree-optimization/110992] [13/14 Regression] missed VRP optimization due to transformation of `a & -zero_one_valued_p` into `a * zero_one_valued_p` pinskia at gcc dot gnu.org 2023-09-15 4:13 ` pinskia at gcc dot gnu.org 2023-09-15 4:33 ` pinskia at gcc dot gnu.org 2023-09-15 16:28 ` pinskia at gcc dot gnu.org 2023-09-15 22:45 ` pinskia at gcc dot gnu.org 2023-09-16 16:33 ` pinskia at gcc dot gnu.org 2023-09-18 23:51 ` pinskia at gcc dot gnu.org 2024-03-07 23:24 ` law at gcc dot gnu.org 2024-03-09 6:40 ` law at gcc dot gnu.org 2024-03-09 8:55 ` xry111 at gcc dot gnu.org 2024-05-21 9:16 ` [Bug tree-optimization/110992] [13/14/15 " jakub at gcc dot gnu.org
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