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* [Bug c/103089] New: -Wmaybe-uninitialized -O2 false positive @ 2021-11-04 20:48 xantares09 at hotmail dot com 2021-11-04 20:54 ` [Bug tree-optimization/103089] " pinskia at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: xantares09 at hotmail dot com @ 2021-11-04 20:48 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103089 Bug ID: 103089 Summary: -Wmaybe-uninitialized -O2 false positive Product: gcc Version: 11.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: xantares09 at hotmail dot com Target Milestone: --- Created attachment 51736 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51736&action=edit minimal reproducer on this example gcc 11.2, 11.1 gives a false positive for -Wmaybe-uninitialized (at O2 only) $ gcc -c -O2 -Wmaybe-uninitialized ks.c ks.c: In function ‘DurbinMatrix’: ks.c:21:18: warning: ‘*H_67 + _146’ may be used uninitialized [-Wmaybe-uninitialized] 21 | H[(m - 1) * m] += (2 * h - 1 > 0 ? pow (2 * h - 1, (double) m) : 0); | ^~ ks.c:21:18: warning: ‘*H_67 + _146’ may be used uninitialized [-Wmaybe-uninitialized] we can see the whole H array is initialized because H[i * m + j] covers the whole (0, m*m( range: H = (double *) malloc ((m * m) * sizeof (double)); for (i = 0; i < m; i++) for (j = 0; j < m; j++) if (i - j + 1 < 0) H[i * m + j] = 0; else H[i * m + j] = 1; ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/103089] -Wmaybe-uninitialized -O2 false positive 2021-11-04 20:48 [Bug c/103089] New: -Wmaybe-uninitialized -O2 false positive xantares09 at hotmail dot com @ 2021-11-04 20:54 ` pinskia at gcc dot gnu.org 2021-11-04 21:04 ` xantares09 at hotmail dot com 2021-11-04 21:16 ` xantares09 at hotmail dot com 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-11-04 20:54 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103089 --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- If I add: if (n <= 0 || m <= 0) __builtin_unreachable(); before the malloc, I get no warning. I think the warning is correct if either n or m is negative. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/103089] -Wmaybe-uninitialized -O2 false positive 2021-11-04 20:48 [Bug c/103089] New: -Wmaybe-uninitialized -O2 false positive xantares09 at hotmail dot com 2021-11-04 20:54 ` [Bug tree-optimization/103089] " pinskia at gcc dot gnu.org @ 2021-11-04 21:04 ` xantares09 at hotmail dot com 2021-11-04 21:16 ` xantares09 at hotmail dot com 2 siblings, 0 replies; 4+ messages in thread From: xantares09 at hotmail dot com @ 2021-11-04 21:04 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103089 --- Comment #2 from xantares09 at hotmail dot com --- indeed, I assumed both were positive, I guess there's no bug then ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/103089] -Wmaybe-uninitialized -O2 false positive 2021-11-04 20:48 [Bug c/103089] New: -Wmaybe-uninitialized -O2 false positive xantares09 at hotmail dot com 2021-11-04 20:54 ` [Bug tree-optimization/103089] " pinskia at gcc dot gnu.org 2021-11-04 21:04 ` xantares09 at hotmail dot com @ 2021-11-04 21:16 ` xantares09 at hotmail dot com 2 siblings, 0 replies; 4+ messages in thread From: xantares09 at hotmail dot com @ 2021-11-04 21:16 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103089 xantares09 at hotmail dot com changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |INVALID Status|UNCONFIRMED |RESOLVED --- Comment #3 from xantares09 at hotmail dot com --- my bad, thanks for the reply ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-11-04 21:16 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-11-04 20:48 [Bug c/103089] New: -Wmaybe-uninitialized -O2 false positive xantares09 at hotmail dot com 2021-11-04 20:54 ` [Bug tree-optimization/103089] " pinskia at gcc dot gnu.org 2021-11-04 21:04 ` xantares09 at hotmail dot com 2021-11-04 21:16 ` xantares09 at hotmail dot com
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