https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65162
Oleg Endo <olegendo at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2015-02-22
Ever confirmed|0 |1
--- Comment #1 from Oleg Endo <olegendo at gcc dot gnu.org> ---
(In reply to Oleg Endo from comment #0)
> The following example is taken from libav, which contains quite some uses of
> this code pattern.
>
> typedef unsigned short int uint16_t;
> union unaligned_16 { uint16_t l; } __attribute__((packed));
>
> int
> test (unsigned char* buf, int bits_per_component)
> {
> (((union unaligned_16 *)(buf))->l) =
> __builtin_bswap16 (bits_per_component == 10 ? 1 : 0);
>
> return 0;
> }
>
BTW, it should actually translate to something like:
mov r6,r0
cmp/eq #10,r0
movt r0
mov.b r0,@(1,r4)
mov #0,r0
rts
mov.b r0,@r4
or
mov r6,r0
cmp/eq #10,r0
movt r0
mov.b r0,@(1,r4)
shlr8 r0
rts
mov.b r0,@r4
