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* [Bug c++/94184] New: Global variable inline constructor elision. @ 2020-03-15 19:36 maxim.yegorushkin at gmail dot com 2020-03-15 19:52 ` [Bug c++/94184] " pinskia at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: maxim.yegorushkin at gmail dot com @ 2020-03-15 19:36 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94184 Bug ID: 94184 Summary: Global variable inline constructor elision. Product: gcc Version: 9.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: maxim.yegorushkin at gmail dot com Target Milestone: --- The following code: struct A { int a_; A(int a) : a_(a) {} }; struct B { int a_; constexpr B(int a) : a_(a) {} }; A a{1}; B b{1}; When compiled with `gcc-9.2 -O3 -march=skylake -mtune=skylake -std=gnu++17` generates a call to `A` constructor for variable `a`: _GLOBAL__sub_I_a: mov DWORD PTR [rip+0x200bd6],0x1 # 601030 <__TMC_END__> ret And no call for `B` constructor for variable `b`, as expected of `constexpr`. `clang-9.0 -O3 -march=skylake -mtune=skylake -std=gnu++17`, however, elides the constructor calls for both `a` and `b` global variables, regardless of `constexpr`. Why can't `gcc` elide the call to `A` constructor for `a`, since `A` constuctor is an inline function with a clear side-effect? https://gcc.godbolt.org/z/5y3cD5 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/94184] Global variable inline constructor elision. 2020-03-15 19:36 [Bug c++/94184] New: Global variable inline constructor elision maxim.yegorushkin at gmail dot com @ 2020-03-15 19:52 ` pinskia at gcc dot gnu.org 2022-10-17 13:40 ` trass3r at gmail dot com 2022-10-17 14:11 ` ppalka at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2020-03-15 19:52 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94184 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |enhancement Keywords| |missed-optimization --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- There is another bug about this already. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/94184] Global variable inline constructor elision. 2020-03-15 19:36 [Bug c++/94184] New: Global variable inline constructor elision maxim.yegorushkin at gmail dot com 2020-03-15 19:52 ` [Bug c++/94184] " pinskia at gcc dot gnu.org @ 2022-10-17 13:40 ` trass3r at gmail dot com 2022-10-17 14:11 ` ppalka at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: trass3r at gmail dot com @ 2022-10-17 13:40 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94184 Trass3r <trass3r at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |trass3r at gmail dot com --- Comment #2 from Trass3r <trass3r at gmail dot com> --- Even simpler example: const struct A { A() {} int a = 0; } a; The global ctor doesn't get eliminated while clang removes it: https://godbolt.org/z/9bjzMbx85 .section .text.startup,"ax",@progbits .type _GLOBAL__sub_I_example.cpp, @function _GLOBAL__sub_I_example.cpp: ret It works if you remove the member a. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/94184] Global variable inline constructor elision. 2020-03-15 19:36 [Bug c++/94184] New: Global variable inline constructor elision maxim.yegorushkin at gmail dot com 2020-03-15 19:52 ` [Bug c++/94184] " pinskia at gcc dot gnu.org 2022-10-17 13:40 ` trass3r at gmail dot com @ 2022-10-17 14:11 ` ppalka at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: ppalka at gcc dot gnu.org @ 2022-10-17 14:11 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94184 Patrick Palka <ppalka at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |DUPLICATE Status|UNCONFIRMED |RESOLVED CC| |ppalka at gcc dot gnu.org --- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> --- dup of PR102876 I think *** This bug has been marked as a duplicate of bug 102876 *** ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-10-17 14:11 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-03-15 19:36 [Bug c++/94184] New: Global variable inline constructor elision maxim.yegorushkin at gmail dot com 2020-03-15 19:52 ` [Bug c++/94184] " pinskia at gcc dot gnu.org 2022-10-17 13:40 ` trass3r at gmail dot com 2022-10-17 14:11 ` ppalka at gcc dot gnu.org
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