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From: "hiraditya at msn dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug ipa/106991] new+delete pair not optimized by g++ at -O3 but optimized at -Os Date: Wed, 21 Sep 2022 21:37:53 +0000 [thread overview] Message-ID: <bug-106991-4-Fvem8NP1Eb@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-106991-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106991 --- Comment #3 from AK <hiraditya at msn dot com> --- Thanks for identifying the underlying issue @Jan After modifying the definition of operator delete. gcc does optimize it at -O3 as well. https://godbolt.org/z/1WPqaWrEr // source code #include<cassert> #include<cstdlib> int volatile gv = 0; void* operator new(long unsigned sz ) { ++gv; return malloc( sz ); } void operator delete(void *p, unsigned long) noexcept { --gv; free(p); } class c { int l; public: c() : l(0) {} int get(){ return l; } }; int caller( void ){ c *f = new c(); assert( f->get() == 0 ); delete f; return gv; } $ $ g++ -std=c++20 -O3 ``` operator new(unsigned long): mov eax, DWORD PTR gv[rip] add eax, 1 mov DWORD PTR gv[rip], eax jmp malloc operator delete(void*, unsigned long): mov eax, DWORD PTR gv[rip] sub eax, 1 mov DWORD PTR gv[rip], eax jmp free caller(): mov eax, DWORD PTR gv[rip] add eax, 1 mov DWORD PTR gv[rip], eax mov eax, DWORD PTR gv[rip] sub eax, 1 mov DWORD PTR gv[rip], eax mov eax, DWORD PTR gv[rip] ret gv: .zero 4 ```
prev parent reply other threads:[~2022-09-21 21:37 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-09-21 4:53 [Bug c++/106991] New: " hiraditya at msn dot com 2022-09-21 8:17 ` [Bug ipa/106991] " rguenth at gcc dot gnu.org 2022-09-21 11:18 ` hubicka at ucw dot cz 2022-09-21 21:37 ` hiraditya at msn dot com [this message]
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