Re: [ANNOUNCE] Git v2.19.0-rc0

> On Wed, Aug 22, 2018 at 6:08 PM Duy Nguyen <pclouds@gmail.com> wrote:
> >
> > On Wed, Aug 22, 2018 at 6:03 PM Jeff King <peff@peff.net> wrote:
> > >
> > > On Wed, Aug 22, 2018 at 07:14:42AM -0400, Derrick Stolee wrote:
> > >
> > > > The other thing I was going to recommend (and I'll try to test this out
> > > > myself later) is to see if 'the_hash_algo->rawsz' is being treated as a
> > > > volatile variable, since it is being referenced through a pointer. Perhaps
> > > > storing the value locally and then casing on it would help?
> > >
> > > I tried various sprinkling of "const" around the declarations to make it
> > > clear that the values wouldn't change once we saw them. But I couldn't
> > > detect any difference. At most I think that would let us hoist the "if"
> > > out of the loop, but gcc still seems unwilling to expand the memcmp when
> > > there are other branches.
> > >
> > > I think if that's the thing we want to have happen, we really do need to
> > > just write it out on that branch rather than saying "memcmp".
> >
> > This reminds me of an old discussion about memcpy() vs doing explicit
> > compare loop with lots of performance measurements..
> 
> Ah found it. Not sure if it is still relevant in light of multiple hash support
> 
> https://public-inbox.org/git/20110427225114.GA16765@elte.hu/