[Bug libstdc++/58104] New: std::call_once appears to fail on standard code

[Bug libstdc++/58104] New: std::call_once appears to fail on standard code

[barto at visionpro dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58104

            Bug ID: 58104
           Summary: std::call_once appears to fail on standard code
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: barto at visionpro dot com

When using std::call_once the code on Linux(gcc 4.7.0) or MacOS (gcc 4.7.3 or
4.8.1) fails to execute

562_ /opt/local/bin/gcc-mp-4.8 -v
Using built-in specs.
COLLECT_GCC=/opt/local/bin/gcc-mp-4.8
COLLECT_LTO_WRAPPER=/opt/local/libexec/gcc/x86_64-apple-darwin12/4.8.1/lto-wrapper
Target: x86_64-apple-darwin12
Configured with: ../gcc-4.8.1/configure --prefix=/opt/local
--build=x86_64-apple-darwin12
--enable-languages=c,c++,objc,obj-c++,lto,fortran,java
--libdir=/opt/local/lib/gcc48 --includedir=/opt/local/include/gcc48
--infodir=/opt/local/share/info --mandir=/opt/local/share/man
--datarootdir=/opt/local/share/gcc-4.8 --with-local-prefix=/opt/local
--with-system-zlib --disable-nls --program-suffix=-mp-4.8
--with-gxx-include-dir=/opt/local/include/gcc48/c++/ --with-gmp=/opt/local
--with-mpfr=/opt/local --with-mpc=/opt/local --with-ppl=/opt/local
--with-cloog=/opt/local --enable-cloog-backend=isl
--disable-cloog-version-check --enable-stage1-checking --enable-lto
--enable-libstdcxx-time --with-as=/opt/local/bin/as --with-ld=/opt/local/bin/ld
--with-ar=/opt/local/bin/ar --with-bugurl=https://trac.macports.org/newticket
--with-pkgversion='MacPorts gcc48 4.8.1_1+universal'
Thread model: posix
gcc version 4.8.1 (MacPorts gcc48 4.8.1_1+universal) 

The code that fails is taken directly from the c++ documentation site:

http://en.cppreference.com/w/cpp/thread/call_once

#include <iostream>
#include <thread>
#include <mutex>

std::once_flag flag;

void do_once()
{
    std::call_once(flag, [](){ std::cout << "Called once" << std::endl; });
}

int main()
{
    std::thread t1(do_once);
    std::thread t2(do_once);
    std::thread t3(do_once);
    std::thread t4(do_once);

    t1.join();
    t2.join();
    t3.join();
    t4.join();
}

The bug appears in the call to call_once (thanks for detail from Jeremy
Huddleston Sequoia on the MacPorts mailing list for the assembly trace)

__once_proxy is just looking up some other function (__once_call) using
__emutls_get_address and executing it (makes sense based on the name).
__emutls_get_address is returning 3 in this instance, so something looks wrong
with emutls:

(lldb) disassemble -n __once_proxy
libstdc++.6.dylib`__once_proxy:
  0x1000e974e:  pushq  %rbp
  0x1000e974f:  movq   %rsp, %rbp
  0x1000e9752:  leaq   463719(%rip), %rdi        ; __emutls_v._ZSt11
_ZSt11__once_call
  0x1000e9759:  callq  0x100101880               ;
libstdc++.6.dylib.__TEXT.__text + 602364
-> 0x1000e975e:  movq   (%rax), %rax
  0x1000e9761:  callq  *%rax
  0x1000e9763:  popq   %rbp
  0x1000e9764:  ret    
(lldb) disassemble -s 0x100101880
libstdc++.6.dylib`__emutls_get_address:
...
(lldb) register read
General Purpose Registers:
      rax = 0x0000000000000003
...

Further this has been shown to fail on 4.7 [gcc version 4.7.3 (MacPorts gcc47
4.7.3_1+universal)]
and in the development build for gcc 4.9 (again through Jeremy)

If this is a configuration issue, what configuration flag is required to make
the feature work?

What versions of the Mac/Linux version of gcc have been shown to work?

[Bug libstdc++/58104] std::call_once appears to fail on standard code

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58104

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Works for me.

Are you using the -pthread flag?

You haven't actually said what fails, what fails to execute?

[Bug libstdc++/58104] std::call_once appears to fail on standard code

[DBarto at visionpro dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58104

--- Comment #2 from DBarto at visionpro dot com ---
I added the -pthread flag and nothing changed.

The code failed to execute at the point noted in the assembly output.

    David

On Aug 8, 2013, at 9:10 AM, redi at gcc dot gnu.org <gcc-bugzilla@gcc.gnu.org>
 wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58104
> 
> --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
> Works for me.
> 
> Are you using the -pthread flag?
> 
> You haven't actually said what fails, what fails to execute?
> 
> -- 
> You are receiving this mail because:
> You reported the bug.

[Bug libstdc++/58104] std::call_once appears to fail on standard code

[DBarto at visionpro dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58104

--- Comment #3 from DBarto at visionpro dot com ---
/opt/local/bin/g++-mp-4.7 -std=c++11 -Wall -Wextra  -pthread -g use_once.cpp -o
use_once
./use_once
571_ ./use_once
Segmentation fault: 11

gdb use_once
(gdb) r
Starting program: /Users/barto/mvp/trunk/unit_test/use_once 
Reading symbols for shared libraries +++.............................. done

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: 13 at address: 0x0000000000000000
[Switching to process 22829 thread 0x1203]
0x0000000100074b20 in __once_proxy ()
(gdb) where
#0  0x0000000100074b20 in __once_proxy ()
#1  0x00007fff8f7e0ff0 in pthread_once ()
#2  0x0000000100001165 in __gthread_once (__once=0x1000055e0,
__func=0x100074b10 <__once_proxy>) at gthr-default.h:718
#3  0x000000010000142d in call_once<do_once()::<lambda()> >
(__once=@0x1000055e0, __f=@0x100293e6f) at mutex:822
#4  0x0000000100001247 in do_once () at use_once.cpp:47
#5  0x0000000100002a29 in
_ZNSt12_Bind_simpleIFPFvvEvEE9_M_invokeIIEEEvSt12_Index_tupleIIXspT_EEE
(this=0x100303aa0) at functional:1598
#6  0x0000000100002979 in std::_Bind_simple<void (*()())()>::operator()
(this=0x100303aa0) at functional:1586
#7  0x0000000100002912 in std::thread::_Impl<std::_Bind_simple<void (*()())()>
>::_M_run (this=0x100303a88) at thread:115
#8  0x00000001000754b0 in execute_native_thread_routine ()
#9  0x00007fff8f7cc1e1 in thread_start ()

On Aug 8, 2013, at 9:10 AM, redi at gcc dot gnu.org <gcc-bugzilla@gcc.gnu.org>
 wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58104
> 
> --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
> Works for me.
> 
> Are you using the -pthread flag?
> 
> You haven't actually said what fails, what fails to execute?
> 
> -- 
> You are receiving this mail because:
> You reported the bug.

[Bug libstdc++/58104] std::call_once appears to fail on standard code

[barto at visionpro dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58104

--- Comment #4 from barto at visionpro dot com ---
Adding the -pthread flag allows the code to compile and execute on Linux.

MacOS still fails to execute.

[Bug libstdc++/58104] std::call_once appears to fail on standard code

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58104

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
"Failed to execute" and "segmentation fault" are not the same thing, it would
help if you actually say what the problem is!

[Bug libstdc++/58104] std::call_once appears to fail on standard code

[barto at visionpro dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58104

--- Comment #6 from barto at visionpro dot com ---
Compiling the code listed in the original bug report with gcc4.8 using the
-pthread flag the program fails to complete execution due to a segmentation
fault while attempting to acquire a std::once_flag object in a call to
std::call_once.

This but only occurs on MacOS X builds.

The code works correctly on Linux with the -pthread option to the compiler.

[Bug target/58104] std::call_once appears to fail on standard code

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58104

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |darwin
          Component|libstdc++                   |target

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
It works ok for others on Mac OS X:
http://gcc.gnu.org/ml/gcc-testresults/2013-07/msg01805.html

[Bug target/58104] std::call_once appears to fail on standard code

[barto at visionpro dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58104

barto at visionpro dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #8 from barto at visionpro dot com ---
So it is a configuration issue related to MacPorts and not specific to gcc or
the libraries.
Closing the bug at gcc.org.