Re: [PATCH] crypto/sha256.c crypto/sha512.c

[Jean-Luc Cooke]

If you take a peek in your/Plumb's crypto/md5.c you've reduced the F1() macro
to the identical operation as the new Ch() inline function.

It reduces gcc's tenancy to re-load values in functions such like:
  (x & y) ^ (~x & z)
  (x & y) ^ (x & z) ^ (y & z)

This works out much nicer:
   z ^ (x & (y ^ z))
   (x & y) | (z & (x | y))

I've seen this in a few .c files (gcc -S blah.c; vim blah.s)

The Ch() and Maj() operations are used a lot in sha256/512.

JLC

On Tue, Jan 27, 2004 at 03:14:53PM -0500, James Morris wrote:
> On Tue, 27 Jan 2004, Jean-Luc Cooke wrote:
> 
> > Optimized the choice and majority fuctions a bit.
> > 
> > Patch:
> >   http://jlcooke.ca/lkml/faster_sha2.patch
> > 
> > Test suite:
> >   http://jlcooke.ca/lkml/faster_sha2.c
> >   build with:
> >     gcc -O3 -s faster_sha2.c -o faster_sha2
> > 
> 
> What kind of performance improvement does this provide?

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