cvs commit: src/include _ctype.h

[Alexey Dokuchaev]

On Thu, Nov 01, 2007 at 12:55:26AM +0300, Andrey Chernov wrote:
> On Tue, Oct 30, 2007 at 10:03:31AM -1000, Juli Mallett wrote:
> > * "Andrey A. Chernov" <ache at FreeBSD.org> [ 2007-10-27 ]
> > 	[ cvs commit: src/include _ctype.h ]
> > > ache        2007-10-27 22:32:28 UTC
> > > 
> > >   FreeBSD src repository
> > > 
> > >   Modified files:
> > >     include              _ctype.h 
> > >   Log:
> > >   Micro-optimization of prev. commit, change
> > >   (_c < 0 || _c >= 128) to (_c & ~0x7F)
> > 
> > Isn't that a non-optimization in code and a minor pessimization of readability?
> > Maybe I'm getting rusty, but those seem to result in nearly identical code on
> > i386 with a relatively modern GCC.  Did you look at the compiler output for this
> > optimization?  Is there a specific expensive instruction you're trying to avoid?
> > For such thoroughyl bit-aligned range checks, you shouldn't even get a branch
> > for the former case.  Is there a platform other than i386 I should look at where
> > the previous expression is more clearly pessimized?  Or a different compiler
> > than GCC?
> 
> For ones who doubts there two tests compiled with -O2. As you may see the 
> result is almost identical (andl vs cmpl):

Q.E.D.  How about to restore original, more reader-friendly version then?

./danfe