public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug analyzer/104576] New: False positive from -Wanalyzer-use-of-uninitialized-value from PR 63311
@ 2022-02-16 22:47 dmalcolm at gcc dot gnu.org
2022-02-16 22:51 ` [Bug analyzer/104576] " dmalcolm at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: dmalcolm at gcc dot gnu.org @ 2022-02-16 22:47 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104576
Bug ID: 104576
Summary: False positive from
-Wanalyzer-use-of-uninitialized-value from PR 63311
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: analyzer
Assignee: dmalcolm at gcc dot gnu.org
Reporter: dmalcolm at gcc dot gnu.org
Target Milestone: ---
The reproducers for PR 63311, both Fortran and C (attachment 33852) currently
generate false positives from -Wanalyzer-use-of-uninitialized-value when
optimization is off (and they are silent when optimization is on).
It seems to be an issue with -fanalyzer thinking that __builtin_sinf could
clobber *flag (which presumably it can't, being pure or const), thus allowing
for the "flag is false" branch to skip initialization of t and tt, and then
later executing the "flag is true" branch.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug analyzer/104576] False positive from -Wanalyzer-use-of-uninitialized-value from PR 63311
2022-02-16 22:47 [Bug analyzer/104576] New: False positive from -Wanalyzer-use-of-uninitialized-value from PR 63311 dmalcolm at gcc dot gnu.org
@ 2022-02-16 22:51 ` dmalcolm at gcc dot gnu.org
2022-02-17 2:41 ` cvs-commit at gcc dot gnu.org
2022-02-17 13:28 ` dmalcolm at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: dmalcolm at gcc dot gnu.org @ 2022-02-16 22:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104576
--- Comment #1 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
Potentially just a dup of PR analyzer/104434, but there might be additional
issues with the reproducer.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug analyzer/104576] False positive from -Wanalyzer-use-of-uninitialized-value from PR 63311
2022-02-16 22:47 [Bug analyzer/104576] New: False positive from -Wanalyzer-use-of-uninitialized-value from PR 63311 dmalcolm at gcc dot gnu.org
2022-02-16 22:51 ` [Bug analyzer/104576] " dmalcolm at gcc dot gnu.org
@ 2022-02-17 2:41 ` cvs-commit at gcc dot gnu.org
2022-02-17 13:28 ` dmalcolm at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-02-17 2:41 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104576
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by David Malcolm <dmalcolm@gcc.gnu.org>:
https://gcc.gnu.org/g:5fbcbcaff7248604e04b39464f4fbd64fbf6e43b
commit r12-7270-g5fbcbcaff7248604e04b39464f4fbd64fbf6e43b
Author: David Malcolm <dmalcolm@redhat.com>
Date: Wed Feb 16 18:21:58 2022 -0500
analyzer: const functions have no side effects [PR104576]
PR analyzer/104576 tracks that we issue a false positive from
-Wanalyzer-use-of-uninitialized-value for the reproducers of PR 63311
when optimization is disabled.
The root cause is that the analyzer was considering that a call to
__builtin_sinf could have side-effects.
This patch fixes things by generalizing the handling for "pure"
functions to also consider "const" functions.
gcc/analyzer/ChangeLog:
PR analyzer/104576
* region-model.cc: Include "calls.h".
(region_model::on_call_pre): Use flags_from_decl_or_type to
generalize check for DECL_PURE_P to also check for ECF_CONST.
gcc/testsuite/ChangeLog:
PR analyzer/104576
* gcc.dg/analyzer/torture/uninit-pr63311.c: New test.
* gcc.dg/analyzer/uninit-pr104576.c: New test.
* gfortran.dg/analyzer/uninit-pr63311.f90: New test.
Signed-off-by: David Malcolm <dmalcolm@redhat.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug analyzer/104576] False positive from -Wanalyzer-use-of-uninitialized-value from PR 63311
2022-02-16 22:47 [Bug analyzer/104576] New: False positive from -Wanalyzer-use-of-uninitialized-value from PR 63311 dmalcolm at gcc dot gnu.org
2022-02-16 22:51 ` [Bug analyzer/104576] " dmalcolm at gcc dot gnu.org
2022-02-17 2:41 ` cvs-commit at gcc dot gnu.org
@ 2022-02-17 13:28 ` dmalcolm at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: dmalcolm at gcc dot gnu.org @ 2022-02-17 13:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104576
David Malcolm <dmalcolm at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |FIXED
--- Comment #3 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
Should be fixed by the above patch.
(In reply to David Malcolm from comment #1)
> Potentially just a dup of PR analyzer/104434, but there might be additional
> issues with the reproducer.
Not quite: this one covers "const" functions not having side-effects, whereas
PR analyzer/104434 concerns the return values of const/pure functions.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-02-17 13:28 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-02-16 22:47 [Bug analyzer/104576] New: False positive from -Wanalyzer-use-of-uninitialized-value from PR 63311 dmalcolm at gcc dot gnu.org
2022-02-16 22:51 ` [Bug analyzer/104576] " dmalcolm at gcc dot gnu.org
2022-02-17 2:41 ` cvs-commit at gcc dot gnu.org
2022-02-17 13:28 ` dmalcolm at gcc dot gnu.org
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).