bug#35321: [PATCH] * src/bytecode.c (exec_byte_code) Unroll Blist3 and Blist4

[Eli Zaretskii]

> From: Alex Gramiak <agrambot@gmail.com>
> Cc: 35321@debbugs.gnu.org
> Date: Fri, 19 Apr 2019 15:31:01 -0600
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> From: Alex Gramiak <agrambot@gmail.com>
> >> Cc: 35321@debbugs.gnu.org
> >> Date: Fri, 19 Apr 2019 14:30:03 -0600
> >> 
> >> > Does this produce any tangible performance gains?
> >> 
> >> It seems to be within error. I was just in the byte compiler recently
> >> and saw that Blist3/4 don't use list3/4 like Blist2 uses list2. If
> >> you're worried about touching older code for little gain, then I guess
> >> it's safer to leave it alone.
> >
> > Is there any reason other than performance to make the change?
> 
> There's no functional difference, so the only remaining aspects are
> readability and similarity with the other BlistX cases. I suppose it
> loses on the readability front, and it's not much of an issue to be
> dissimilar to Blist2. Perhaps it's best to leave this alone after all.
> 
> > Also, are Blist3/4 used frequently enough to justify the change?
> 
> They're used any time (list x y z) and (list w x y z) are byte-compiled,
> so I imagine they're used quite a bit.

OK, thanks.  I'm undecided on this.  Stefan, any comments?