Re: [Boost-bugs] [Boost C++ Libraries] #12330: boost::thread starts with invalid FPU control word value in Embarcadero C++ Builder

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #12330: boost::thread starts with invalid FPU control word value in Embarcadero C++ Builder
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2016-09-05 07:55:16

#12330: boost::thread starts with invalid FPU control word value in Embarcadero C++
Builder
-------------------------------------------------+-------------------------
  Reporter:  Ville-Valtteri Tiittanen <ville-    |      Owner:  viboes
  valtteri.tiittanen@…>                          |     Status:  assigned
      Type:  Support Requests                    |  Component:  thread
 Milestone:  To Be Determined                    |   Severity:  Regression
   Version:  Boost 1.55.0                        |   Keywords:
Resolution:                                      |
-------------------------------------------------+-------------------------

Comment (by Ville-Valtteri Tiittanen <ville-valtteri.tiittanen@…>):

 What need do you mean?
 - C++ standard specifies that floating point control word should be
 inherited from the parent thread.
 - Source code in the bug report is a full program
 - I have tested this with Boost 1.55.0, using Embarcadero C++ Builder
 10.1.
 - I am using bcc32c, which is the new compiler for this version. To run
 the program with bcc32c compiler, you need to compile for 32-bit target
 and uncheck "Project -> Options -> C++ Compiler -> Use 'classic' Borland
 compiler".

 You will need the same compiler to reproduce this bug.

 This works correctly in C++ Builder XE8, which is earlier version of the
 C++ Builder, and is using "classic Borland compiler". XE8 uses Boost
 1.39.0.

 That can be tested with the following program:


 {{{
 #include <tchar.h>
 #define BOOST_THREAD_USE_LIB
 #include <boost/thread.hpp>
 #include <cstdio>
 #include <cfloat>

 extern "C" { namespace boost { void tss_cleanup_implemented() { } } }

 void print_cw()
 {
         const unsigned int cw = _control87(0, 0);
         printf("%X\n", cw);
 }

 void print_cw_2()
 {
         _fpreset();
         print_cw();
 }

 int _tmain(int argc, _TCHAR* argv[])
 {
         print_cw();

         boost::thread t2(&print_cw);
         t2.join();

         boost::thread t3(&print_cw_2);
         t3.join();

         getchar();
         return 0;
 }
 }}}

 When compiled with the classic compiler, the output is correct:


 {{{
 1372
 1372
 1372
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/12330#comment:3>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.