This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
C aliasing rules question.
- From: Richard Guenther <rguenth at tat dot physik dot uni-tuebingen dot de>
- To: gcc at gcc dot gnu dot org
- Date: Sun, 18 May 2003 23:38:01 +0200 (CEST)
- Subject: C aliasing rules question.
Hi!
gcc 3.3 now warns about
static inline int f_trunc(float f)
{
f -= 0.5f;
f += (3<<22);
return *((int*)&f) - 0x4b400000;
}
to violate C aliasing rules (I see the code is broken as is), is
the following "fix" to the code ok (gcc doesnt warn anymore), as
char* is special wrt aliasing?
static inline int f_trunc(float f)
{
f -= 0.5f;
f += (3<<22);
return *((int*)(char*)&f) - 0x4b400000;
}
Or is this still invalid? Is it at least ok to tell _gcc_ about the
aliasing?
Thanks,
Richard.