Bug#446067: g++-4.1 in etch has incorrect output

[Matthieu Lemerre]

Package: g++-4.1
Version: 4.1.1-21

The g++ shipped with debian is incorrect. g++ seems to be able to use
non-constant initializer for global variables (I don't known if this is
standard C++ behaviour) , but this doesn't work
when optimizations are on with the version of gcc shipped with debian.

I checked with other versions of gcc (4.2, 3.3) and it works perfectly.

I attach a sample test file and sample session.

Best Regards
Matthieu Lemerre

PS: I encountered the bug in fpu/fpu_const.cc in Bochs, so maybe the
debian package for bochs is affected by this bug too.


#if 0

~$ gcc test2.c
test2.c:29: error: initializer element is not constant


~$ g++ test2.c -Wall
test2.c: In function 'int main()':
test2.c:35: warning: format '%x' expects type 'unsigned int', but
argument 3 has type 'Bit64u'
~$ ./a.out
Reg: 3fff 0


~$ g++ test2.c -O2 -Wall
test2.c: In function 'int main()':
test2.c:35: warning: format '%x' expects type 'unsigned int', but
argument 3 has type 'Bit64u'
~$ ./a.out
Reg: 0 0
~$

~$ gcc -v
gcc version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)
#endif


test2.c:

  typedef unsigned long long Bit64u;
  typedef   signed int       Bit32s;
  typedef unsigned short     Bit16u;

struct floatx80 {
    Bit64u fraction;
    Bit16u exp;
};

#define BX_CONST64(x)  (x##LL)

#include <stdio.h>

inline struct floatx80 packFloatx80(int zSign, Bit32s zExp, Bit64u zSig)
{
  struct floatx80 z;
    z.fraction = zSig;
    z.exp = (zSign << 15) + zExp;
    return z;
}

extern const struct floatx80 Const_1;
const struct floatx80 Const_1    = packFloatx80(0, 0x3fff,
BX_CONST64(0x8000000000000000));

int
main()
{
  struct floatx80 reg = Const_1;
  printf("Reg: %x %x\n", reg.exp, reg.fraction);
}



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