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* [Bug c++/105646] New: g++ does not raise xxx is used uninitialized warning under some conditions @ 2022-05-18 14:07 cfy1990 at gmail dot com 2022-05-18 14:13 ` [Bug c++/105646] " cfy1990 at gmail dot com ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: cfy1990 at gmail dot com @ 2022-05-18 14:07 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105646 Bug ID: 105646 Summary: g++ does not raise xxx is used uninitialized warning under some conditions Product: gcc Version: 12.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: cfy1990 at gmail dot com Target Milestone: --- g++ version: g++ (Compiler-Explorer-Build-gcc--binutils-2.38) 12.1.0 Code link: https://godbolt.org/z/5MansKa5c Compile arguments: -std=c++11 -Wextra -Wall -O2 Code: int f1(); int f2(){ bool v2{v2}; // used uninitialized warning auto const & a = f1(); return a; } int f3(){ auto const & a = f1(); bool v3{v3}; // no warning in g++, got uninitialized warning in clang return a; } ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/105646] g++ does not raise xxx is used uninitialized warning under some conditions 2022-05-18 14:07 [Bug c++/105646] New: g++ does not raise xxx is used uninitialized warning under some conditions cfy1990 at gmail dot com @ 2022-05-18 14:13 ` cfy1990 at gmail dot com 2022-09-29 8:24 ` [Bug tree-optimization/105646] g++ does not raise "xxx may be used uninitialized" warning on dead code when optimizing cvs-commit at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: cfy1990 at gmail dot com @ 2022-05-18 14:13 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105646 --- Comment #1 from cfy1990 at gmail dot com --- When compile without -O2, g++ will generate "'v3' may be used uninitialized" warning. code link: https://godbolt.org/z/r3sY4srx9 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/105646] g++ does not raise "xxx may be used uninitialized" warning on dead code when optimizing 2022-05-18 14:07 [Bug c++/105646] New: g++ does not raise xxx is used uninitialized warning under some conditions cfy1990 at gmail dot com 2022-05-18 14:13 ` [Bug c++/105646] " cfy1990 at gmail dot com @ 2022-09-29 8:24 ` cvs-commit at gcc dot gnu.org 2022-09-29 8:24 ` rguenth at gcc dot gnu.org 2022-10-27 0:54 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: cvs-commit at gcc dot gnu.org @ 2022-09-29 8:24 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105646 --- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>: https://gcc.gnu.org/g:a1cd4d52d6ef90b977fb2d80c1cf17f3efa5b01d commit r13-2926-ga1cd4d52d6ef90b977fb2d80c1cf17f3efa5b01d Author: Richard Biener <rguenther@suse.de> Date: Fri Aug 19 15:11:14 2022 +0200 tree-optimization/105646 - re-interpret always executed in uninit diag The following fixes PR105646, not diagnosing int f1(); int f3(){ auto const & a = f1(); bool v3{v3}; return a; } with optimization because the early uninit diagnostic pass only diagnoses always executed cases. The patch does this by re-interpreting what always executed means and choosing to ignore exceptional and abnormal control flow for this. At the same time it improves things as suggested in a comment - when the value-numbering run done without optimizing figures there's a fallthru path, consider blocks on it as always executed. PR tree-optimization/105646 * tree-ssa-uninit.cc (warn_uninitialized_vars): Pre-compute the set of fallthru reachable blocks from function entry and use that to determine wlims.always_executed. * g++.dg/uninit-pr105646.C: New testcase. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/105646] g++ does not raise "xxx may be used uninitialized" warning on dead code when optimizing 2022-05-18 14:07 [Bug c++/105646] New: g++ does not raise xxx is used uninitialized warning under some conditions cfy1990 at gmail dot com 2022-05-18 14:13 ` [Bug c++/105646] " cfy1990 at gmail dot com 2022-09-29 8:24 ` [Bug tree-optimization/105646] g++ does not raise "xxx may be used uninitialized" warning on dead code when optimizing cvs-commit at gcc dot gnu.org @ 2022-09-29 8:24 ` rguenth at gcc dot gnu.org 2022-10-27 0:54 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: rguenth at gcc dot gnu.org @ 2022-09-29 8:24 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105646 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|ASSIGNED |RESOLVED Known to work| |13.0 Resolution|--- |FIXED --- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> --- Fixed on trunk. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/105646] g++ does not raise "xxx may be used uninitialized" warning on dead code when optimizing 2022-05-18 14:07 [Bug c++/105646] New: g++ does not raise xxx is used uninitialized warning under some conditions cfy1990 at gmail dot com ` (2 preceding siblings ...) 2022-09-29 8:24 ` rguenth at gcc dot gnu.org @ 2022-10-27 0:54 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2022-10-27 0:54 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105646 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Target Milestone|--- |13.0 ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-10-27 0:54 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-05-18 14:07 [Bug c++/105646] New: g++ does not raise xxx is used uninitialized warning under some conditions cfy1990 at gmail dot com 2022-05-18 14:13 ` [Bug c++/105646] " cfy1990 at gmail dot com 2022-09-29 8:24 ` [Bug tree-optimization/105646] g++ does not raise "xxx may be used uninitialized" warning on dead code when optimizing cvs-commit at gcc dot gnu.org 2022-09-29 8:24 ` rguenth at gcc dot gnu.org 2022-10-27 0:54 ` pinskia at gcc dot gnu.org
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