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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug analyzer/106325] -Wanalyzer-null-dereference false positive due to analyzer not making assumptions for `__attribute__((nonnull))` Date: Tue, 06 Dec 2022 18:28:20 +0000 [thread overview] Message-ID: <bug-106325-4-Meb4Wg6spV@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-106325-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106325 --- Comment #7 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:dcfc7ac94dbcf6c86c0c58ce6dc1d8bd853e4093 commit r13-4520-gdcfc7ac94dbcf6c86c0c58ce6dc1d8bd853e4093 Author: David Malcolm <dmalcolm@redhat.com> Date: Tue Dec 6 13:26:57 2022 -0500 analyzer: use __attribute__((nonnull)) at top level of analysis [PR106325] PR analyzer/106325 reports false postives from -Wanalyzer-null-dereference on code like this: __attribute__((nonnull)) void foo_a (Foo *p) { foo_b (p); switch (p->type) { /* ... */ } } where foo_b (p) has a: g_return_if_fail (p); that expands to: if (!p) { return; } The analyzer "sees" the comparison against NULL in foo_b, and splits the analysis into the NULL and not-NULL cases; later, back in foo_a, at switch (p->type) it complains that p is NULL. Previously we were only using __attribute__((nonnull)) as something to complain about when it was violated; we weren't using it as a source of knowledge. This patch fixes things by making the analyzer respect __attribute__((nonnull)) at the top-level of the analysis: any such params are now assumed to be non-NULL, so that the analyzer assumes the g_return_if_fail inside foo_b doesn't fail when called from foo_a Doing so fixes the false positives. gcc/analyzer/ChangeLog: PR analyzer/106325 * region-model-manager.cc (region_model_manager::get_or_create_null_ptr): New. * region-model-manager.h (region_model_manager::get_or_create_null_ptr): New decl. * region-model.cc (region_model::on_top_level_param): Add "nonnull" param and make use of it. (region_model::push_frame): When handling a top-level entrypoint to the analysis, determine which params __attribute__((nonnull)) applies to, and pass to on_top_level_param. * region-model.h (region_model::on_top_level_param): Add "nonnull" param. gcc/testsuite/ChangeLog: PR analyzer/106325 * gcc.dg/analyzer/attr-nonnull-pr106325.c: New test. * gcc.dg/analyzer/attribute-nonnull.c (test_6): New. (test_7): New. Signed-off-by: David Malcolm <dmalcolm@redhat.com>
next prev parent reply other threads:[~2022-12-06 18:28 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-07-16 13:11 [Bug analyzer/106325] New: `analyzer-null-dereference` gets thrown on a parameter on a function marked with `__attribute__((nonnull))` alex at zrythm dot org 2022-07-16 13:14 ` [Bug analyzer/106325] " alex at zrythm dot org 2022-07-16 13:25 ` alex at zrythm dot org 2022-07-16 15:36 ` dmalcolm at gcc dot gnu.org 2022-12-05 22:58 ` [Bug analyzer/106325] -Wanalyzer-null-dereference false positive due to analyzer not making assumptions for `__attribute__((nonnull))` dmalcolm at gcc dot gnu.org 2022-12-05 23:00 ` dmalcolm at gcc dot gnu.org 2022-12-05 23:08 ` dmalcolm at gcc dot gnu.org 2022-12-06 18:28 ` cvs-commit at gcc dot gnu.org [this message] 2022-12-06 18:56 ` dmalcolm at gcc dot gnu.org 2023-03-29 18:18 ` cvs-commit at gcc dot gnu.org 2023-03-29 19:29 ` dmalcolm at gcc dot gnu.org
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