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From: "solar-gcc at openwall dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/59124] [4.8/4.9/5 Regression] Wrong warnings "array subscript is above array bounds" Date: Wed, 18 Feb 2015 02:22:00 -0000 [thread overview] Message-ID: <bug-59124-4-Kfnv1PzX2L@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-59124-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59124 Alexander Peslyak <solar-gcc at openwall dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |solar-gcc at openwall dot com --- Comment #8 from Alexander Peslyak <solar-gcc at openwall dot com> --- Here's another testcase: $ gcc -S -Wall -O2 -funroll-loops testcase.c testcase.c: In function 'DES_std_set_key': testcase.c:14:17: warning: array subscript is above array bounds [-Warray-bounds] while (DES_key[i++]) k += 2; ^ =============== 8< =============== static int DES_KS_updates; static char DES_key[16]; void DES_std_set_key(char *key) { int i, j, k, l; j = key[0]; for (k = i = 0; (l = DES_key[i]) && (j = key[i]); i++) ; if (!j) { j = i; while (DES_key[i++]) k += 2; } if (k < j && ++DES_KS_updates) { } DES_key[0] = key[0]; } =============== >8 =============== GCC 4.7.4 and below report no warning, 4.8.0 and 4.9.2 report the warning above. Either -O2 -funroll-loops or -O3 result in the warning; simple -O2 does not. While i++ could potentially run beyond the end of DES_key[], depending on what's in DES_key[] and key[], this isn't the case in the program this snippet is taken from (and simplified), whereas the warning definitively claims "is" rather than "might be". For comparison, Dmitry's first testcase (from this bug's description) results in no warning with -O2 -funroll-loops (but does give the warning to me with -O3, as reported by Dmitry), whereas his second testcase (from comment 2) also reports the warning with -O2 -funroll-loops (but not with simple -O2). I tested this with 4.9.2. I hope this is similar enough to add to this bug (same affected versions, one of the two testcases also affected by -funroll-loops).
next prev parent reply other threads:[~2015-02-18 2:22 UTC|newest] Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-11-14 0:44 [Bug tree-optimization/59124] New: [4.8 " d.g.gorbachev at gmail dot com 2013-11-14 9:51 ` [Bug tree-optimization/59124] [4.8/4.9 " rguenth at gcc dot gnu.org 2013-11-14 17:56 ` d.g.gorbachev at gmail dot com 2013-11-21 14:39 ` rguenth at gcc dot gnu.org 2014-03-12 14:33 ` jakub at gcc dot gnu.org 2014-05-22 9:03 ` [Bug tree-optimization/59124] [4.8/4.9/4.10 " rguenth at gcc dot gnu.org 2014-12-19 13:25 ` [Bug tree-optimization/59124] [4.8/4.9/5 " jakub at gcc dot gnu.org 2015-01-27 9:50 ` rguenth at gcc dot gnu.org 2015-01-27 10:59 ` rguenth at gcc dot gnu.org 2015-02-18 2:22 ` solar-gcc at openwall dot com [this message] 2015-02-18 4:37 ` solar-gcc at openwall dot com 2015-02-19 14:14 ` rguenth at gcc dot gnu.org 2015-02-24 13:09 ` rguenth at gcc dot gnu.org 2015-04-16 12:14 ` [Bug tree-optimization/59124] [4.8/4.9/5/6 " georgmueller at gmx dot net 2015-05-26 15:34 ` georgmueller at gmx dot net 2015-06-01 23:49 ` daniel at imperfectcode dot com 2015-06-23 8:16 ` rguenth at gcc dot gnu.org 2015-06-26 19:53 ` [Bug tree-optimization/59124] [4.9/5/6 " jakub at gcc dot gnu.org 2015-06-26 20:26 ` jakub at gcc dot gnu.org 2015-09-10 21:04 ` pangbw at gmail dot com 2015-09-11 0:29 ` manu at gcc dot gnu.org 2015-09-11 16:13 ` pangbw at gmail dot com 2015-09-11 16:51 ` manu at gcc dot gnu.org 2015-09-17 18:18 ` pangbw at gmail dot com 2015-09-17 19:02 ` pangbw at gmail dot com 2015-09-18 17:59 ` pangbw at gmail dot com 2015-09-18 18:32 ` manu at gcc dot gnu.org 2015-09-18 19:17 ` manu at gcc dot gnu.org 2015-09-18 21:11 ` pangbw at gmail dot com 2015-09-22 20:06 ` pangbw at gmail dot com 2021-01-05 9:14 ` [Bug tree-optimization/59124] [6 " szotsaki at gmail dot com
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