[Bug c++/30332] [4.1/4.2/4.3 regression] bit-field: optimization BUG?

["rguenth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #4 from rguenth at gcc dot gnu dot org  2007-02-21 15:12 -------
With 4.1.3 for C we have, even without optimizing

> ./xgcc -B. -o t t.c -Wall
t.c: In function 'main':
t.c:13: warning: format '%llx' expects type 'long long unsigned int', but
argument 2 has type 'long unsigned int:33'
> ./t
9

For C++ we for all optimizations get
> ./t
200000009


The difference after gimplification is

main ()
{
  <unnamed type> D.2220;
  int D.2221;
  struct S x;
  <unnamed type> z;

  x.a = 8589934591;
  D.2220 = x.a;
  z = D.2220 + 10;
  printf (&"%llx\n"[0], z);
  D.2221 = 0;
  return D.2221;
}

vs.

int main() ()
{
  long long unsigned int D.2823;
  int D.2824;

  {
    struct S x;
    long long unsigned int z;

    x.a = 8589934591;
    D.2823 = x.a;
    z = D.2823 + 10;
    printf (&"%llx\n"[0], z);
    D.2824 = 0;
    return D.2824;
  }
  D.2824 = 0;
  return D.2824;
}

i.e. typeof(+x.a) yields a different result for C and C++.  For C we leave
bitfield types bigger than int alone and don't promote them.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30332