[EMAIL PROTECTED] writes:
> On Mon, Jun 12, 2006 at 12:30:50PM +0000, [EMAIL PROTECTED] wrote:
> > On Mon, Jun 12, 2006 at 02:21:21PM +0200, Richard Guenther wrote:
> > > On 6/12/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> > > >On Mon, Jun 12, 2006 at 01:01:47PM +0100, Andrew Haley wrote:
> > > >>
> > > >> I'm starting to be a little suspicious about host2little(). I wonder
> > > >> if that's well-defined.
> > > >>
> > > >> I'm just guessing here becasue I can't see the code. Is it possible
> > > >
> > > > template<typename T> T swap_endian(T x)
> > > > {
> > > > char* a = reinterpret_cast<char*>(&x);
> > > > char* b = a + sizeof(T) - 1;
> > > > while (a<b) {
> > > > char tmp = *a;
> > > > *a++ = *b;
> > > > *b-- = tmp;
> > > > }
> > > > return x;
> > > > }
> > > >
> > > > template<typename T> T host2little(T x)
> > > > {
> > > > unsigned u = 1; return (*reinterpret_cast<char*>(&u) ? x :
> > > > swap_endian(x));
> > > > }
> > >
> > > You are violating aliasing rules. Try -fno-strict-aliasing, which
> > > should make the code
> > > work, or fix it.
> >
> > Hmmm - don't grok; I'll do some googling. Compiling now with
> > -fno-strict-aliasing, but the manual says -O2 includes
> > -strict-aliasing, so what gives?
>
> Indeed, -fno-strict-aliasing makes no difference; its still broken.
Well, that is interesting! I think both Richard Guenther and I both
thought you had an aliasing problem somewhere: all those pointer casts
are something of a red flag...
OK, well, we're stuck until you can make a test case.
Andrew.
