------- Comment #6 from jakub at gcc dot gnu dot org 2009-05-20 20:05 -------
There are plenty other possible builtin bswap optimizations. E.g.
extern void bar (void);
void foo (int x)
{
if (__builtin_bswap32 (x) == __builtin_bswap32 (0x1234567))
bar ();
}
should be optimized into if (x == 0x1234567) (only for EQ_EXPR/NE_EXPR),
similarly __builtin_bswap32 (x) == 0x1234567 should be optimized into
x == __builtin_bswap32 (0x1234567) because the latter can be swapped at compile
time, similarly __builtin_bswap32 (__builtin_bswap32 (x) | 0x1234) could
be optimized into x | __builtin_bswap32 (0x1234) (similarly for ^ or & or ~),
etc. The question is if enough projects start using these builtins to make it
worth spending compile time on it and what exact optimizations are useful on
real-world code.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40210
