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* [Bug middle-end/104232] New: spurious -Wuse-after-free after conditional free @ 2022-01-25 20:31 msebor at gcc dot gnu.org 2022-01-25 20:32 ` [Bug middle-end/104232] [12 Regression] " msebor at gcc dot gnu.org ` (7 more replies) 0 siblings, 8 replies; 9+ messages in thread From: msebor at gcc dot gnu.org @ 2022-01-25 20:31 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104232 Bug ID: 104232 Summary: spurious -Wuse-after-free after conditional free Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: middle-end Assignee: unassigned at gcc dot gnu.org Reporter: msebor at gcc dot gnu.org Target Milestone: --- The test case below was reduced from https://bugzilla.redhat.com/show_bug.cgi?id=2043195 (it's been greatly simplified). It shows a false positive caused by the warning's overly simplistic PHI handling: the warning warns on any PHI use with an operand that's been passed to free in a block that dominates the use. $ cat rhbz2043195.c && gcc -O2 -S -Wall -fdump-tree-waccess3=/dev/stdout rhbz2043195.c static inline void freep (void *p) { __builtin_free (*(void**)p); } char *f (void); int g (void) { __attribute__ ((__cleanup__ (freep))) char *s = 0, *t = 0; t = f (); if (!t) return 0; s = f (); return 1; } ;; Function g (g, funcdef_no=1, decl_uid=1984, cgraph_uid=2, symbol_order=1) In function ‘freep’, inlined from ‘g’ at rhbz2043195.c:10:47: rhbz2043195.c:3:3: warning: pointer ‘s’ used after ‘__builtin_free’ [-Wuse-after-free] 3 | __builtin_free (*(void**)p); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ In function ‘freep’, inlined from ‘g’ at rhbz2043195.c:10:55: rhbz2043195.c:3:3: note: call to ‘__builtin_free’ here 3 | __builtin_free (*(void**)p); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ pointer_query counters: index cache size: 21 index entries: 3 access cache size: 6 access entries: 3 hits: 1 misses: 3 failures: 0 max_depth: 3 int g () { char * s; char * _1; char * _2; int _3; <bb 2> [local count: 1073741824]: _1 = f (); if (_1 == 0B) goto <bb 4>; [30.95%] else goto <bb 3>; [69.05%] <bb 3> [local count: 741418729]: _2 = f (); <bb 4> [local count: 1073741824]: # _3 = PHI <0(2), 1(3)> # s_10 = PHI <_1(2), _2(3)> __builtin_free (_1); __builtin_free (s_10); return _3; } ^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug middle-end/104232] [12 Regression] spurious -Wuse-after-free after conditional free 2022-01-25 20:31 [Bug middle-end/104232] New: spurious -Wuse-after-free after conditional free msebor at gcc dot gnu.org @ 2022-01-25 20:32 ` msebor at gcc dot gnu.org 2022-01-25 20:35 ` msebor at gcc dot gnu.org ` (6 subsequent siblings) 7 siblings, 0 replies; 9+ messages in thread From: msebor at gcc dot gnu.org @ 2022-01-25 20:32 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104232 Martin Sebor <msebor at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Blocks| |104075 Assignee|unassigned at gcc dot gnu.org |msebor at gcc dot gnu.org Ever confirmed|0 |1 Status|UNCONFIRMED |ASSIGNED Keywords| |diagnostic Last reconfirmed| |2022-01-25 URL| |https://bugzilla.redhat.com | |/show_bug.cgi?id=2043195 Summary|spurious -Wuse-after-free |[12 Regression] spurious |after conditional free |-Wuse-after-free after | |conditional free Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104075 [Bug 104075] bogus/missing -Wuse-after-free ^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug middle-end/104232] [12 Regression] spurious -Wuse-after-free after conditional free 2022-01-25 20:31 [Bug middle-end/104232] New: spurious -Wuse-after-free after conditional free msebor at gcc dot gnu.org 2022-01-25 20:32 ` [Bug middle-end/104232] [12 Regression] " msebor at gcc dot gnu.org @ 2022-01-25 20:35 ` msebor at gcc dot gnu.org 2022-01-26 7:50 ` rguenth at gcc dot gnu.org ` (5 subsequent siblings) 7 siblings, 0 replies; 9+ messages in thread From: msebor at gcc dot gnu.org @ 2022-01-25 20:35 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104232 Martin Sebor <msebor at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- URL|https://bugzilla.redhat.com |https://bugzilla.redhat.com |/show_bug.cgi?id=2043195 |/show_bug.cgi?id=2043915 --- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> --- The correct URL is https://bugzilla.redhat.com/show_bug.cgi?id=2043915 ^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug middle-end/104232] [12 Regression] spurious -Wuse-after-free after conditional free 2022-01-25 20:31 [Bug middle-end/104232] New: spurious -Wuse-after-free after conditional free msebor at gcc dot gnu.org 2022-01-25 20:32 ` [Bug middle-end/104232] [12 Regression] " msebor at gcc dot gnu.org 2022-01-25 20:35 ` msebor at gcc dot gnu.org @ 2022-01-26 7:50 ` rguenth at gcc dot gnu.org 2022-01-31 15:41 ` msebor at gcc dot gnu.org ` (4 subsequent siblings) 7 siblings, 0 replies; 9+ messages in thread From: rguenth at gcc dot gnu.org @ 2022-01-26 7:50 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104232 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Target Milestone|--- |12.0 Priority|P3 |P1 ^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug middle-end/104232] [12 Regression] spurious -Wuse-after-free after conditional free 2022-01-25 20:31 [Bug middle-end/104232] New: spurious -Wuse-after-free after conditional free msebor at gcc dot gnu.org ` (2 preceding siblings ...) 2022-01-26 7:50 ` rguenth at gcc dot gnu.org @ 2022-01-31 15:41 ` msebor at gcc dot gnu.org 2022-01-31 15:46 ` msebor at gcc dot gnu.org ` (3 subsequent siblings) 7 siblings, 0 replies; 9+ messages in thread From: msebor at gcc dot gnu.org @ 2022-01-31 15:41 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104232 Martin Sebor <msebor at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |patch --- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> --- Patch: https://gcc.gnu.org/pipermail/gcc-patches/2022-January/ ^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug middle-end/104232] [12 Regression] spurious -Wuse-after-free after conditional free 2022-01-25 20:31 [Bug middle-end/104232] New: spurious -Wuse-after-free after conditional free msebor at gcc dot gnu.org ` (3 preceding siblings ...) 2022-01-31 15:41 ` msebor at gcc dot gnu.org @ 2022-01-31 15:46 ` msebor at gcc dot gnu.org 2022-01-31 15:47 ` msebor at gcc dot gnu.org ` (2 subsequent siblings) 7 siblings, 0 replies; 9+ messages in thread From: msebor at gcc dot gnu.org @ 2022-01-31 15:46 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104232 --- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> --- *** Bug 104269 has been marked as a duplicate of this bug. *** ^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug middle-end/104232] [12 Regression] spurious -Wuse-after-free after conditional free 2022-01-25 20:31 [Bug middle-end/104232] New: spurious -Wuse-after-free after conditional free msebor at gcc dot gnu.org ` (4 preceding siblings ...) 2022-01-31 15:46 ` msebor at gcc dot gnu.org @ 2022-01-31 15:47 ` msebor at gcc dot gnu.org 2022-01-31 19:06 ` cvs-commit at gcc dot gnu.org 2022-01-31 19:08 ` msebor at gcc dot gnu.org 7 siblings, 0 replies; 9+ messages in thread From: msebor at gcc dot gnu.org @ 2022-01-31 15:47 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104232 --- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> --- The full link to the patch: https://gcc.gnu.org/pipermail/gcc-patches/2022-January/589366.html ^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug middle-end/104232] [12 Regression] spurious -Wuse-after-free after conditional free 2022-01-25 20:31 [Bug middle-end/104232] New: spurious -Wuse-after-free after conditional free msebor at gcc dot gnu.org ` (5 preceding siblings ...) 2022-01-31 15:47 ` msebor at gcc dot gnu.org @ 2022-01-31 19:06 ` cvs-commit at gcc dot gnu.org 2022-01-31 19:08 ` msebor at gcc dot gnu.org 7 siblings, 0 replies; 9+ messages in thread From: cvs-commit at gcc dot gnu.org @ 2022-01-31 19:06 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104232 --- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Martin Sebor <msebor@gcc.gnu.org>: https://gcc.gnu.org/g:48d3191e7bd6245bd2df625731f1ad9207a26655 commit r12-6947-g48d3191e7bd6245bd2df625731f1ad9207a26655 Author: Martin Sebor <msebor@redhat.com> Date: Mon Jan 31 12:04:55 2022 -0700 Constrain PHI handling in -Wuse-after-free [PR104232]. Resolves: PR middle-end/104232 - spurious -Wuse-after-free after conditional free gcc/ChangeLog: PR middle-end/104232 * gimple-ssa-warn-access.cc (pointers_related_p): Add argument. Handle PHIs. Add a synonymous overload. (pass_waccess::check_pointer_uses): Call pointers_related_p. gcc/testsuite/ChangeLog: PR middle-end/104232 * g++.dg/warn/Wuse-after-free4.C: New test. * gcc.dg/Wuse-after-free-2.c: New test. * gcc.dg/Wuse-after-free-3.c: New test. ^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug middle-end/104232] [12 Regression] spurious -Wuse-after-free after conditional free 2022-01-25 20:31 [Bug middle-end/104232] New: spurious -Wuse-after-free after conditional free msebor at gcc dot gnu.org ` (6 preceding siblings ...) 2022-01-31 19:06 ` cvs-commit at gcc dot gnu.org @ 2022-01-31 19:08 ` msebor at gcc dot gnu.org 7 siblings, 0 replies; 9+ messages in thread From: msebor at gcc dot gnu.org @ 2022-01-31 19:08 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104232 Martin Sebor <msebor at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |FIXED Status|ASSIGNED |RESOLVED --- Comment #6 from Martin Sebor <msebor at gcc dot gnu.org> --- Fixed in r12-6947. ^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2022-01-31 19:08 UTC | newest] Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-01-25 20:31 [Bug middle-end/104232] New: spurious -Wuse-after-free after conditional free msebor at gcc dot gnu.org 2022-01-25 20:32 ` [Bug middle-end/104232] [12 Regression] " msebor at gcc dot gnu.org 2022-01-25 20:35 ` msebor at gcc dot gnu.org 2022-01-26 7:50 ` rguenth at gcc dot gnu.org 2022-01-31 15:41 ` msebor at gcc dot gnu.org 2022-01-31 15:46 ` msebor at gcc dot gnu.org 2022-01-31 15:47 ` msebor at gcc dot gnu.org 2022-01-31 19:06 ` cvs-commit at gcc dot gnu.org 2022-01-31 19:08 ` msebor at gcc dot gnu.org
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