On Tue, 23 Apr 2013, Niels Möller wrote:
Martin Storsjö <[email protected]> writes:
Hmm, yes, I think that might have been the case. So since we can't
rely on that being aligned anyway, we could just as well skip the 8
byte offset.
If it works now, I don't think we should touch this code further before
release.
Yes, that's probably wisest.
For later optimization (if it really makes a difference to performance
if we use aligned or unaligned loads and stores here? I don't know),
one could keep the 8 byte extra allocation, then do something like
lea 8(%rsp), %r10
and $-16, %r10
(%r10 should always be free for scratch use at both entry and exit,
right?). Then %r10 will be 16 byte aligned, and hold either %rsp or %rsp
+ 8. And we can then do fully aligned loads and stores of the xmm
registers via offsets from %r10.
That would probably work. I don't know these things well enough to say
whether there's any serious performance to be gained by doing this,
compared to the inconvenience of wasting one register.
// Martin
_______________________________________________
nettle-bugs mailing list
[email protected]
http://lists.lysator.liu.se/mailman/listinfo/nettle-bugs
