Re: [harder@ifa.au.dk: Speed of all-completions]

[David Kastrup <dak@gnu.org>]

Andreas Schwab <schwab@suse.de> writes:

> David Kastrup <dak@gnu.org> writes:
> 
> > Andreas Schwab <schwab@suse.de> writes:
> >
> >> This is due to this change:
> >> 
> >> 	(Ftry_completion, Fall_completions, Ftest_completion): Bind
> >> 	case-fold-search to the value of completion-ignore-case when
> >> 	checking completion-regexp-list.
> >> 
> >> I've checked in a fix that avoids the overhead of specbind when
> >> completion-regexp-list is empty.
> >
> > At the cost of being more expensive when it isn't.
> 
> Why is it more expensive?  The check for CONSP (completion-regexp-list)
> has to be done anyway, and can be CSE'd by the compiler.

Because you are redoing the binding for every element in the loop,
while it is needed only once.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum