http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55177
Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
AssignedTo|unassigned at gcc dot |ebotcazou at gcc dot
|gnu.org |gnu.org
--- Comment #4 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2012-11-02
17:45:54 UTC ---
> The first example isn't *that* dumb, as a cut-down test case of real code
> which may look more complex in reality.
OK, and I can indeed think of some usage patterns in real life.
> If the real code really *is* as simple as my test case, you're right that
> perhaps we *could* optimise it ourselves by eschewing the normal accessor
> macros for explicit-endian values, and manually byteswapping the constant
> instead.
>
> But really, we shouldn't *have* to. The compiler can see what's happening, and
> it can deal with it a whole lot better than we can, especially when it comes
> to loads and stores.
Another category would be comparisons then:
int compare1 (int x)
{
return __builtin_bswap32 (x) == 0xdeadbeef;
}
int compare2 (int x, int y)
{
return __builtin_bswap32 (x) == __builtin_bswap32 (y);
}
Will have a look shortly.
