low level optimization

[Jim Giles]

> [...]     but why is it so horrible to you to document
> to the users of your optimized libraries that certain
> arguments to certain functions must be carefully
> non-aliased?  [...]

It's not horrible.  You miss my point if you believe that I would
oppose that.  You give me a portable way to declare to the compiler
that two (or more) arguments are assumed not to be aliased and I will 
rejoice.

The problem is that what people are recommending is _not_ portable
and is _not_ an explicit declaration (so the end user has to guess 
which variables the compiler optimized in this way and which are 
safe to alias).

J. Giles