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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/40635] bogus name and location in 'may be used uninitialized' warning Date: Wed, 15 Dec 2021 18:43:32 +0000 [thread overview] Message-ID: <bug-40635-4-spSFu20HiA@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-40635-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40635 --- Comment #16 from Martin Sebor <msebor at gcc dot gnu.org> --- With the patch in comment #13 committed in g:9695e1c23be5b5c55d572ced152897313ddb96ae GCC 12 prints the following for the test case in comment #0: pr40635.c: In function ‘server_init’: pr40635.c:14:9: warning: ‘s42’ may be used uninitialized in this function [-Wmaybe-uninitialized] 14 | int s42, x; | ^~~ But it doesn't show where the uninitialized variable is used. GCC 11 only points to the variable's use but doesn't say which variable it is: pr40635.c: In function ‘server_init’: pr40635.c:39:8: warning: ‘s42’ may be used uninitialized in this function [-Wmaybe-uninitialized] 39 | if (sockt_rd < 0) | ^ So things have gotten both better and worse. The reason why the GCC 12 warning doesn't point to the use is because the use statement (_28 = _16 < 0; in basic block 8 below) has no location: <bb 8> [local count: 1073741824]: # _16 = PHI <[pr40635.c:22:20] -1(12), s42_9(7), [pr40635.c:29:16] -1(14), s42_18(D)(11), s42_9(13)> [pr40635.c:38:5] foo (); _28 = _16 < 0; _5 = (int) _28; _4 = -_5; return _4; The location can still be found in the mergephi3 dump (pr40635.c.120t.mergephi3) and is gone from the phiopt2 dump (pr40635.c.121t.phiopt2): <bb 8> [local count: 5226752]: <bb 9> [local count: 1073741824]: # _16 = PHI <[../pr40635.c:22:20] -1(3), [../pr40635.c:30:12] s42_20(7), [../pr40635.c:29:16] -1(8)> [../pr40635.c:38:5] foo (); [../pr40635.c:39:8] if (_16 < 0) goto <bb 10>; [0.73%] else goto <bb 11>; [99.27%] <bb 10> [local count: 7838309]: <bb 11> [local count: 1073741824]: # _1 = PHI <[../pr40635.c:40:16] -1(10), [../pr40635.c:41:12] 0(9)> return _1; }
next prev parent reply other threads:[~2021-12-15 18:43 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <bug-40635-4@http.gcc.gnu.org/bugzilla/> 2013-11-01 21:56 ` manu at gcc dot gnu.org 2013-12-19 10:17 ` manu at gcc dot gnu.org 2013-12-19 10:40 ` philipp at marek dot priv.at 2013-12-19 10:51 ` manu at gcc dot gnu.org 2013-12-19 10:57 ` philipp at marek dot priv.at 2013-12-19 10:59 ` philipp at marek dot priv.at 2021-03-25 21:07 ` msebor at gcc dot gnu.org 2021-03-25 21:08 ` msebor at gcc dot gnu.org 2021-03-25 22:40 ` msebor at gcc dot gnu.org 2021-12-15 18:43 ` msebor at gcc dot gnu.org [this message] 2021-12-15 18:48 ` [Bug tree-optimization/40635] [12 Regression] " msebor at gcc dot gnu.org 2021-12-15 19:00 ` msebor at gcc dot gnu.org 2021-12-15 19:14 ` pinskia at gcc dot gnu.org 2021-12-18 10:46 ` pinskia at gcc dot gnu.org 2022-01-21 13:56 ` rguenth at gcc dot gnu.org 2022-03-17 19:25 ` msebor at gcc dot gnu.org 2022-03-17 22:00 ` pinskia at gcc dot gnu.org 2022-05-06 8:29 ` [Bug tree-optimization/40635] [12/13 " jakub at gcc dot gnu.org 2022-11-20 3:11 ` law at gcc dot gnu.org 2022-12-05 15:00 ` rguenth at gcc dot gnu.org 2022-12-05 15:51 ` cvs-commit at gcc dot gnu.org 2023-05-08 12:21 ` [Bug tree-optimization/40635] [12 " rguenth at gcc dot gnu.org
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