On Mon, Mar 03, 2014 at 05:04:45PM +0800, lin zuojian wrote:
> > No. As I wrote earlier, the alternative is to use unaligned stores for ARM,
> > I've asked Lin to benchmark that compared to his patch, but haven't seen
> > that done yet.
> I have not benchmark yet.But according to what I hear from an ARM Engineer in
> Huawei,
> unaligned accessing usually slow.And not recommand to use too much.
It is expected it will not be as fast as aligned store, the question is if
an unaligned 32-bit store is faster than 4 8-bit stores, and/or if the cost of
the unaligned stores is bad enough (note, usually it is just a few stores in
the prologue and epilogue) to offset for the penalties introduced by
realigning the stack (typically one extra register that has to be live, plus
the cost of the realignment itself).
Jakub
