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From: "vlad at solidsands dot nl" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/111773] New: Inconsistent optimization of replaced operator new() Date: Wed, 11 Oct 2023 15:59:40 +0000 [thread overview] Message-ID: <bug-111773-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111773 Bug ID: 111773 Summary: Inconsistent optimization of replaced operator new() Product: gcc Version: 13.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: vlad at solidsands dot nl Target Milestone: --- #include <new> #include <cstdint> #include <cstdio> int a[10]; void* operator new(std::size_t) { return a; } int main() { int* p = static_cast<int*>(::operator new(sizeof(int))); std::ptrdiff_t x = a - p; printf("%ld %d", x, x == 0); return 0; } Here, GCC with -O1 optimizes 'x' to 0 and 'x == 0' to false at the same time. Compiler explorer link: https://godbolt.org/z/4Y3eeY56r --- Also, possibly related: #include <new> void* operator new(std::size_t sz) { throw std::bad_alloc{}; } int main() { int* p1 = static_cast<int*>(::operator new(sizeof(int))); return 10; } Here, again with -O1, terminate is not called, and the program returned successfully. However, the program returned 0 instead of 10. Compiler explorer link: https://godbolt.org/z/9oczTzP7s
next reply other threads:[~2023-10-11 15:59 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-10-11 15:59 vlad at solidsands dot nl [this message] 2023-10-11 16:05 ` [Bug c++/111773] " pinskia at gcc dot gnu.org 2023-10-12 8:15 ` [Bug ipa/111773] " rguenth at gcc dot gnu.org 2023-10-12 8:48 ` sjames at gcc dot gnu.org 2023-10-13 6:34 ` cvs-commit at gcc dot gnu.org 2023-10-13 6:43 ` rguenth at gcc dot gnu.org 2023-10-18 14:09 ` vlad at solidsands dot nl 2023-10-19 6:16 ` rguenth at gcc dot gnu.org
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