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From: "bernd.edlinger at hotmail dot de" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/103830] New: volatile optimized away Date: Sun, 26 Dec 2021 10:00:14 +0000 [thread overview] Message-ID: <bug-103830-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103830 Bug ID: 103830 Summary: volatile optimized away Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-optimization Assignee: unassigned at gcc dot gnu.org Reporter: bernd.edlinger at hotmail dot de Target Milestone: --- the following test case is intentionally writing at address 0, it is IMHO invalid to optimize it away (at -Og): $ cat empty-inline.cc /* This testcase is part of GDB, the GNU debugger. Copyright 2021 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ /* PR 25987 */ struct MyClass; struct ptr { MyClass* get() { return t; } /* line 21 */ MyClass* t; }; struct MyClass { void call(); }; void MyClass::call() { *(volatile char*)(nullptr) = 1; /* line 26 */ } static void intermediate(ptr p) { p.get()->call(); /* line 29 */ } int main() { intermediate(ptr{new MyClass}); } /* EOF */ previously this used to SIGSEGV in line 26, but no longer with git master from December 18th at least. I think it is rather common to have something at address zero, for instance interrupt tables or device registers, and therefore it's not OK to optimize those volatile accesses away.
next reply other threads:[~2021-12-26 10:00 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-12-26 10:00 bernd.edlinger at hotmail dot de [this message] 2021-12-26 10:10 ` [Bug rtl-optimization/103830] " pinskia at gcc dot gnu.org 2021-12-26 10:19 ` [Bug ipa/103830] [12 Regression] null pointer access optimized away by removing function call at -Og pinskia at gcc dot gnu.org 2021-12-27 16:20 ` jakub at gcc dot gnu.org 2022-01-04 13:35 ` rguenth at gcc dot gnu.org 2022-01-04 14:52 ` hubicka at kam dot mff.cuni.cz 2022-01-28 12:02 ` rguenth at gcc dot gnu.org 2022-01-28 12:04 ` rguenth at gcc dot gnu.org 2022-01-28 12:06 ` rguenth at gcc dot gnu.org 2022-01-28 12:08 ` bernd.edlinger at hotmail dot de
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