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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/89800] -Waggressive-loop-optimization warning doesn't have useful location Date: Wed, 01 Sep 2021 18:19:00 +0000 [thread overview] Message-ID: <bug-89800-4-oh55C1P2Wk@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-89800-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89800 Martin Sebor <msebor at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |msebor at gcc dot gnu.org Status|NEW |RESOLVED Target Milestone|--- |12.0 Known to fail| |10.2.0, 11.2.0, 8.3.0, | |9.2.0 Component|tree-optimization |middle-end Assignee|unassigned at gcc dot gnu.org |msebor at gcc dot gnu.org Resolution|--- |FIXED --- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> --- GCC 12 prints the full inlining stack for the test case in comment #0 (thanks to r12-1992 and related): In function ‘T foo(T, int) [with T = int]’, inlined from ‘int bar(int)’ at pr89800.C:10:28, inlined from ‘int main()’ at pr89800.C:14:13: pr89800.C:5:3: warning: iteration 2147483647 invokes undefined behavior [-Waggressive-loop-optimizations] 5 | while (n--) | ^~~~~ pr89800.C:5:3: note: within this loop Similarly, for the bigger test case GCC prints the following output (-Wno-system-headers is no longer necessary): In file included from /build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/stl_algobase.h:66, from /build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/array:43, from pr89800-2.C:1: In function ‘constexpr void std::__advance(_InputIterator&, _Distance, std::input_iterator_tag) [with _InputIterator = std::_Fwd_list_const_iterator<int>; _Distance = long int]’, inlined from ‘constexpr void std::advance(_InputIterator&, _Distance) [with _InputIterator = std::_Fwd_list_const_iterator<int>; _Distance = long int]’ at /build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/stl_iterator_base_funcs.h:207:21, inlined from ‘constexpr _BidirectionalIterator std::prev(_BidirectionalIterator, typename std::iterator_traits<_Iter>::difference_type) [with _BidirectionalIterator = std::_Fwd_list_const_iterator<int>]’ at /build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/stl_iterator_base_funcs.h:233:19, inlined from ‘typename T::value_type back(const T&) [with T = std::forward_list<int>]’ at pr89800-2.C:9:20: /build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/stl_iterator_base_funcs.h:153:7: warning: iteration 9223372036854775807 invokes undefined behavior [-Waggressive-loop-optimizations] 153 | while (__n--) | ^~~~~ /build/gcc-master/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/stl_iterator_base_funcs.h:153:7: note: within this loop With that I think we can resolve this as fixed. (The poor phrasing should be handled separately. Please open a new bug for it.)
parent reply other threads:[~2021-09-01 18:19 UTC|newest] Thread overview: expand[flat|nested] mbox.gz Atom feed [parent not found: <bug-89800-4@http.gcc.gnu.org/bugzilla/>]
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