[Bug c++/56220] New: g++ failed to initialize a __thread local bool variable.

["gccbug at xiahaiqu dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56220

             Bug #: 56220
           Summary: g++ failed to initialize a __thread local bool
                    variable.
    Classification: Unclassified
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: gccbug@xiahaiqu.com


c++ front end failed to initialize a "__thread" local "bool" variable with
value "true" in a multi-threaded environment. I also did more tests, it could
initialize the variable to "false" correctly. Also it could initialize an "int"
variable correctly.

The bug would also be reproduced with both driver "gcc" and "g++":

witch@desktop:/tmp$ g++ --version
g++ (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

witch@desktop:/tmp$ cat t.cpp
#include <stdio.h>
#include <pthread.h>

void g(bool x) {
    printf("%d\n", x);
}

void* f(void* arg) {
    static __thread bool i = true;
    g(i);
    return NULL;
}

int main() {
    pthread_t a, b;
    pthread_create(&a, NULL, &f, NULL);
    pthread_create(&b, NULL, &f, NULL);
    pthread_join(a, NULL);
    pthread_join(b, NULL);
    return 0;
}
witch@desktop:/tmp$ g++ t.cpp -O2 -pthread
witch@desktop:/tmp$ ./a.out 
1
1
witch@desktop:/tmp$ g++ t.cpp -O0 -pthread
witch@desktop:/tmp$ ./a.out 
0
0