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From: "gcc-bugzilla at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/16115] New: 3.5: problem with argument passing via temporary (breaks auto_ptr) Date: Mon, 21 Jun 2004 16:43:00 -0000 [thread overview] Message-ID: <20040621164318.16115.snyder@fnal.gov> (raw) The code y1.cc below seems to produce the wrong result if it is compiled with -O2. (It works ok, however, with either -O1 or -O3.) $ g++ -O2 -o y1 y1.cc $ ./y1 a bfffb690 d 0 0 dtor 1 bfffb690 $ In the last line of output, i expect the value of a printed by the destructor to be 0; however, it is still 1. Here is the generated code for the foo() and main() functions (passed through c++filt, omitting exception handling labels and cleanups): foo(auto_ptr): pushl %ebp xorl %edx, %edx movl %esp, %ebp xorl %eax, %eax subl $24, %esp movl %edx, 8(%esp) movl %eax, 4(%esp) movl $.LC0, (%esp) call printf leave ret main: pushl %ebp movl %esp, %ebp subl $40, %esp andl $-16, %esp subl $16, %esp movl %esi, -4(%ebp) leal -24(%ebp), %esi movl %ebx, -8(%ebp) movl $1, -24(%ebp) movl %esi, 4(%esp) movl $.LC1, (%esp) call printf movl %esi, (%esp) call foo(auto_ptr) movl -24(%ebp), %eax movl %esi, 8(%esp) movl $.LC2, (%esp) movl %eax, 4(%esp) call printf movl -8(%ebp), %ebx xorl %eax, %eax movl -4(%ebp), %esi movl %ebp, %esp popl %ebp ret ... .LC0: .string "d %x %x\n" .LC1: .string "a %x\n" .LC2: .string "dtor %x %x\n" It looks like something is going wrong with handling the temporary object that gets passed to foo(). With gcc 3.4, this code works as expected, so this is a regression. FYI, here is an earlier stage in the reduction of the test case, with the auto_ptr class left intact. Here, the problem shows up as a double deletion of the allocated object. Again, it shows up at -O2, but not at -O1 or -O3. $ g++ -O2 -o y y.cc $ ./y a ctor 804a008 a dtor 804a008 a dtor 804a008 $ y.cc ------------------------------------------- #include <memory> struct A { A() { printf ("a ctor %x\n", this); } ~A() { printf ("a dtor %x\n", this); } }; void foo (std::auto_ptr<A> a) { delete a.release(); } int main () { foo (std::auto_ptr<A> (new A)); } ------------------------------------------------ Environment: System: Linux karma 2.6.6 #15 Thu May 13 15:07:54 EDT 2004 i686 i686 i386 GNU/Linux Architecture: i686 <machine, os, target, libraries (multiple lines)> host: i686-pc-linux-gnu build: i686-pc-linux-gnu target: i686-pc-linux-gnu configured with: /home/sss/gcc/gcc/configure --prefix=/usr/local/gcc --enable-threads=posix --enable-long-long --enable-languages=c,c++,f95 How-To-Repeat: Compile the following with -O2 and run: y1.cc ------------------------------------------ extern "C" int printf(const char*, ...); struct auto_ptr { int _M_ptr; auto_ptr(int p) : _M_ptr(1) { printf ("a %x\n", this); } ~auto_ptr() { printf ("dtor %x %x\n", _M_ptr, this); } void release() { _M_ptr = 0; } auto_ptr(const auto_ptr&a) : _M_ptr (a._M_ptr) { printf ("b %x\n", this); } }; void foo (auto_ptr a) { a.release(); printf ("d %x %x\n", a._M_ptr, 0); } int main () { foo (0); } ------------------------------------------------ ------- Additional Comments From snyder at fnal dot gov 2004-06-21 16:43 ------- Fix: <how to correct or work around the problem, if known (multiple lines)> -- Summary: 3.5: problem with argument passing via temporary (breaks auto_ptr) Product: gcc Version: 3.5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: snyder at fnal dot gov CC: gcc-bugs at gcc dot gnu dot org GCC build triplet: i686-pc-linux-gnu GCC host triplet: i686-pc-linux-gnu GCC target triplet: i686-pc-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16115
next reply other threads:[~2004-06-21 16:43 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2004-06-21 16:43 gcc-bugzilla at gcc dot gnu dot org [this message] 2004-06-21 16:55 ` [Bug tree-optimization/16115] [3.5 regression] " bangerth at dealii dot org 2004-06-21 18:26 ` [Bug tree-optimization/16115] [3.5 regression] double-destruction " bangerth at dealii dot org 2004-06-22 6:34 ` pinskia at gcc dot gnu dot org 2004-06-22 8:00 ` rth at gcc dot gnu dot org 2004-06-22 21:08 ` rth at gcc dot gnu dot org 2004-06-22 21:48 ` rth at gcc dot gnu dot org 2004-06-24 20:07 ` cvs-commit at gcc dot gnu dot org 2004-06-24 20:08 ` cvs-commit at gcc dot gnu dot org 2004-06-24 21:16 ` pinskia at gcc dot gnu dot org 2004-07-06 7:16 ` cvs-commit at gcc dot gnu dot org 2004-07-06 7:23 ` mmitchel at gcc dot gnu dot org 2004-07-18 5:44 ` cvs-commit at gcc dot gnu dot org 2004-07-18 13:41 ` cvs-commit at gcc dot gnu dot org 2004-07-18 14:15 ` pinskia at gcc dot gnu dot org
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