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From: "ppluzhnikov at google dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/53265] Warn when undefined behavior implies smaller iteration count Date: Mon, 29 Apr 2013 23:18:00 -0000 [thread overview] Message-ID: <bug-53265-4-J6HiA6a3mZ@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-53265-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53265 --- Comment #27 from Paul Pluzhnikov <ppluzhnikov at google dot com> 2013-04-29 23:18:29 UTC --- Here is a reduced test case in which g++ (GCC) 4.9.0 20130426 (experimental) produces infinite loop with -O2 due to aggressive loop optimization, but doesn't warn (making the bug in user code hard to find). g++ -O2 test.cc -Wall && ./a.out Segmentation fault g++ -O2 test.cc -Wall -fno-aggressive-loop-optimizations && ./a.out && echo ok ok struct Puzzle { int r[9]; int ignored[18]; } p; int a, b; int main() { int c = 0; for (b = 0; b < 27; b++) { if (p.r[b] == 0) c |= p.r[a]; if (c != 0) return c; } return c; }
next prev parent reply other threads:[~2013-04-29 23:18 UTC|newest] Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-05-07 14:09 [Bug tree-optimization/53265] New: " amonakov at gcc dot gnu.org 2012-05-07 14:21 ` [Bug tree-optimization/53265] " rguenth at gcc dot gnu.org 2013-01-29 17:23 ` jakub at gcc dot gnu.org 2013-01-31 12:13 ` jakub at gcc dot gnu.org 2013-03-11 10:15 ` rguenth at gcc dot gnu.org 2013-03-11 14:14 ` rguenth at gcc dot gnu.org 2013-03-11 14:16 ` rguenth at gcc dot gnu.org 2013-03-11 14:17 ` rguenth at gcc dot gnu.org 2013-03-11 15:49 ` jakub at gcc dot gnu.org 2013-03-11 15:59 ` rguenth at gcc dot gnu.org 2013-03-11 16:16 ` amonakov at gcc dot gnu.org 2013-03-11 16:42 ` manu at gcc dot gnu.org 2013-03-11 16:50 ` manu at gcc dot gnu.org 2013-03-11 17:11 ` jakub at gcc dot gnu.org 2013-03-12 11:25 ` jakub at gcc dot gnu.org 2013-03-12 11:26 ` jakub at gcc dot gnu.org 2013-03-12 11:30 ` jakub at gcc dot gnu.org 2013-03-12 11:48 ` jakub at gcc dot gnu.org 2013-03-12 12:37 ` jakub at gcc dot gnu.org 2013-03-12 12:41 ` jakub at gcc dot gnu.org 2013-03-12 14:15 ` jakub at gcc dot gnu.org 2013-03-12 20:10 ` jakub at gcc dot gnu.org 2013-03-12 21:48 ` jakub at gcc dot gnu.org 2013-03-13 10:36 ` jakub at gcc dot gnu.org 2013-03-13 11:01 ` rguenth at gcc dot gnu.org 2013-03-14 9:14 ` jakub at gcc dot gnu.org 2013-03-14 10:55 ` jakub at gcc dot gnu.org 2013-04-29 23:18 ` ppluzhnikov at google dot com [this message] 2013-04-30 6:07 ` jakub at gcc dot gnu.org 2013-04-30 6:46 ` jakub at gcc dot gnu.org 2014-02-16 13:14 ` jackie.rosen at hushmail dot com 2023-06-09 16:52 ` pinskia at gcc dot gnu.org
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