Re: Unaligned accesses in sha1dc

Linus Torvalds [off-list ref] writes:

Dereferencing an unaligned pointer may be "undefined" in some
technical meaning, but it sure as hell isn't undefined in reality, and
compilers that willfully do stupid things should not be catered to
overly. Reality is a lot more important.

Thanks for succinctly putting it this way.  I think you said the
above number of times, and I was looking for one of them to include
a reference to in the response I was preparing, but this message
made it unnecessary ;-)

And I think gcc can be tweaked to use "movbe" on x86 with the right
magic incantation (ie not just __builtin_bswap32(), but also the
switch to enable the new instructions).  So having code to detect gcc
and using __builtin_bswap32() would indeed be a good thing.