Re: gcc compile-time performance

[Geoff Keating <geoffk at geoffk dot org>]

"David S. Miller" <davem@redhat.com> writes:

>    From: dewar@gnat.com (Robert Dewar)
>    Date: Sun, 19 May 2002 08:10:15 -0400 (EDT)
>    
>    Depending on the source representation, this is something that should only
>    cost when used, and it won't be used much in practice.
>    
> The minimum is a function call per character, that can't
> cost the same as a simple char dereference.

You ought to be able to optimise this down to a single array or bitmap
lookup per character, to determine whether the character is the first
one of a multibyte sequence or a state-changing character.  The C
standard guarantees that most of the characters that appear in a C
program are always single bytes, so it'll be rare that you ever have
to actually call back to the C library.

-- 
- Geoffrey Keating <geoffk@geoffk.org> <geoffk@redhat.com>