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From: "eggert at cs dot ucla.edu" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug analyzer/109628] New: -Wanalyzer-use-of-uninitialized-value false positive on static storage Date: Tue, 25 Apr 2023 22:17:08 +0000 [thread overview] Message-ID: <bug-109628-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109628 Bug ID: 109628 Summary: -Wanalyzer-use-of-uninitialized-value false positive on static storage Product: gcc Version: 13.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: analyzer Assignee: dmalcolm at gcc dot gnu.org Reporter: eggert at cs dot ucla.edu Target Milestone: --- Created attachment 54919 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54919&action=edit compile with "gcc -fanalyzer -S" to reproduce the bug I ran into this problem when compiling GNU coreutils fmt.c. This is with gcc (GCC) 13.0.1 20230401 (Red Hat 13.0.1-0) on x86-64. Compile the attached program with: gzip -d u.i.gz gcc -fanalyzer -S u.i GCC outputs the following diagnostic which is a false positive because 'this' points to the static array unused_word_type, and static storage by definition is initialized. u.i: In function ‘base_cost’: u.i:5950:7: warning: use of uninitialized value ‘((unsigned char*)&*this)[16]’ [CWE-457] [-Wanalyzer-use-of-uninitialized-value] 5950 | if (this->paren) | ^~~~ ‘fmt_paragraph’: events 1-4 | | 5894 | fmt_paragraph (void) | | ^~~~~~~~~~~~~ | | | | | (1) entry to ‘fmt_paragraph’ |...... | 5903 | for (start = word_limit - 1; start >= unused_word_type; start--) | | ~~~~~~~~~~~~~~~~~~~~~~~~~ | | | | | (2) following ‘true’ branch... | 5904 | { | 5905 | best = ((COST) (! (! ((COST) 0 < (COST) -1)) ? (COST) -1 : ((((COST) 1 << ((sizeof (COST) * 8 | | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | | | | | (3) ...to here | 5906 | ) - 2)) - 1) * 2 + 1))); | | ~~~~~~~~~~~~~~~~~~~~~~~ |...... | 5913 | wcost = line_cost (w, len) + w->best_cost; | | ~~~~~~~~~~~~~~~~~~ | | | | | (4) calling ‘line_cost’ from ‘fmt_paragraph’ | +--> ‘line_cost’: events 5-7 | | 5957 | line_cost (WORD *next, int len) | | ^~~~~~~~~ | | | | | (5) entry to ‘line_cost’ |...... | 5961 | if (next == word_limit) | | ~ | | | | | (6) following ‘true’ branch... | 5962 | return 0; | | ~ | | | | | (7) ...to here | <------+ | ‘fmt_paragraph’: events 8-9 | | 5913 | wcost = line_cost (w, len) + w->best_cost; | | ^~~~~~~~~~~~~~~~~~ | | | | | (8) returning to ‘fmt_paragraph’ from ‘line_cost’ |...... | 5922 | if (w == word_limit) | | ~ | | | | | (9) following ‘true’ branch... | ‘fmt_paragraph’: event 10 | |cc1: | (10): ...to here | ‘fmt_paragraph’: event 11 | | 5927 | start->best_cost = best + base_cost (start); | | ^~~~~~~~~~~~~~~~~ | | | | | (11) calling ‘base_cost’ from ‘fmt_paragraph’ | +--> ‘base_cost’: events 12-13 | | 5932 | base_cost (WORD *this) | | ^~~~~~~~~ | | | | | (12) entry to ‘base_cost’ |...... | 5950 | if (this->paren) | | ~~~~ | | | | | (13) use of uninitialized value ‘((unsigned char*)&*this)[16]’ here |
next reply other threads:[~2023-04-25 22:17 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-04-25 22:17 eggert at cs dot ucla.edu [this message] 2024-02-16 19:21 ` [Bug analyzer/109628] " dmalcolm at gcc dot gnu.org
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