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From: "rob.desbois at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/60367] Default argument object is not getting constructed Date: Mon, 03 Mar 2014 11:20:00 -0000 [thread overview] Message-ID: <bug-60367-4-4zqcFITs9c@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-60367-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60367 --- Comment #5 from rob.desbois at gmail dot com --- The following is a side-by-side diff of the disassembly of the incorrect version vs. a correct version (defaulting the parameter with = foo{}). The object foo has a single member of type char initialized in default, move, and copy ctors. incorrect version | correct version -------------------------------------------|----------------------------------- push %rbp push %rbp mov %rsp,%rbp mov %rsp,%rbp push %rbx push %rbx sub $0x28,%rsp | sub $0x18,%rsp lea -0x11(%rbp),%rax lea -0x11(%rbp),%rax mov %rax,%rdi mov %rax,%rdi callq 0x400bbe <_ZN3fooC2Ev> | callq 0x400bb8 <_ZN3fooC2Ev> movzbl -0x11(%rbp),%eax | lea -0x11(%rbp),%rax mov %al,-0x30(%rbp) < lea -0x30(%rbp),%rax < mov %rax,%rdi mov %rax,%rdi callq 0x4009f0 <_Z6test_a3foo> | callq 0x400a50 <_Z6test_b3foo> lea -0x11(%rbp),%rax lea -0x11(%rbp),%rax mov %rax,%rdi mov %rax,%rdi callq 0x400bfe <_ZN3fooD2Ev> | callq 0x400bf8 <_ZN3fooD2Ev> mov $0x0,%eax mov $0x0,%eax jmp 0x400b65 <main+85> | jmp 0x400b5e <main+78> mov %rax,%rbx mov %rax,%rbx lea -0x11(%rbp),%rax lea -0x11(%rbp),%rax mov %rax,%rdi mov %rax,%rdi callq 0x400bfe <_ZN3fooD2Ev> | callq 0x400bf8 <_ZN3fooD2Ev> mov %rbx,%rax mov %rbx,%rax mov %rax,%rdi mov %rax,%rdi callq 0x4008b0 <_Unwind_Resume@plt> callq 0x4008b0 <_Unwind_Resume@plt> add $0x28,%rsp | add $0x18,%rsp pop %rbx pop %rbx pop %rbp pop %rbp retq retq It does look like the incorrect version on the left could be bitwise-copying the default-constructed object. As an aside - both versions have a single constructor call but TWO destructor calls...
next prev parent reply other threads:[~2014-03-03 11:20 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-02-28 17:30 [Bug c++/60367] New: " rob.desbois at gmail dot com 2014-03-02 15:14 ` [Bug c++/60367] " rob.desbois at gmail dot com 2014-03-02 22:24 ` rob.desbois at gmail dot com 2014-03-03 10:32 ` rob.desbois at gmail dot com 2014-03-03 11:20 ` rob.desbois at gmail dot com [this message] 2014-03-04 11:20 ` redi at gcc dot gnu.org 2014-03-04 11:20 ` redi at gcc dot gnu.org 2014-03-10 19:23 ` jason at gcc dot gnu.org 2014-03-11 21:08 ` reichelt at gcc dot gnu.org 2014-05-13 16:05 ` jason at gcc dot gnu.org 2014-05-13 16:06 ` jason at gcc dot gnu.org 2014-07-08 17:33 ` redi at gcc dot gnu.org 2015-03-03 18:13 ` vhaisman at gmail dot com 2015-03-03 18:15 ` redi at gcc dot gnu.org
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