gdb/178: Floating Point NaN on first fp operation when compiling with -lpthread

[vladm at cs dot tut dot fi]

>Number:         178
>Category:       gdb
>Synopsis:       Floating Point NaN on first fp operation when compiling with -lpthread
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jul 23 12:48:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Marius VLAD (Digital Media Institute, Tampere Univ. of Technology, FINLAND)
>Release:        gdb-5.0
>Organization:
>Environment:
Linux Mandrake 8.0
Linux cookie.dmi.tut.fi 2.4.2-15mdk #1 Wed Mar 14 12:15:14 CET 2001 i686 unknown
Intel P3 800Mhz
256MB RAM (DRAM 400Mhz)
gcc 2.96 (gcc-gcc-2.96-0.44mdk)
gdb 5.0 (gdb-5.0-10mdk)
glibc (glibc-2.2.2-4mdk)
>Description:
I get a strange NAN value when running a program in gdb somewhere 
around first floating point operation, and this only occure
if I compile the program with -lpthread...
For example:
$cat test.cpp
#include <stdio.h>
int main()
{
  float f=1.0;
  printf("f=%5.3f\n",f);
  printf("f=%5.3f\n",f);
  return 0;
}
$ gcc -g -lpthread test.cpp
$ ./a.out
f=1.000
f=1.000
$ gdb a.out
GNU gdb 5.0
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This GDB was configured as "i386-mandrake-linux"...
(gdb) run
Starting program: /home/marius/work/VideoServer/a.out
[New Thread 1024 (LWP 4524)]
f=  nan
f=1.000

Program exited normally.
Current language:  auto; currently c
(gdb) b main
Breakpoint 1 at 0x8048476: file test.cpp, line 4.
(gdb) run
Starting program: /home/marius/work/VideoServer/a.out
[New Thread 1024 (LWP 4526)]
[Switching to Thread 1024 (LWP 4526)]

Breakpoint 1, main () at test.cpp:4
4         float f=1.0;
Current language:  auto; currently c++
(gdb) n
5         printf("f=%5.3f\n",f);
(gdb) p f
$1 = 1
(gdb) n
f=  nan
6         printf("f=%5.3f\n",f);
(gdb) p f
$2 = 1
(gdb) n
f=  nan
7         return 0;
(gdb) n
8       }
(gdb) n
0x400570de in __libc_start_main () from /lib/libc.so.6
(gdb) n
Single stepping until exit from function __libc_start_main,
which has no line number information.

Program exited normally.
(gdb)

>How-To-Repeat:
the error is persistent ...
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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Content-Type: application/octet-stream; name="test.cpp"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="test.cpp"

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