Re: Register allocation with shadowed locals at same level

[Rob Kendrick <rjek@...>]

On Mon, 18 Jan 2010 11:10:48 -0200
Roberto Ierusalimschy <roberto@inf.puc-rio.br> wrote:

> > Nod.  Although a simple algorithm to detect if there's already a
> > local with the same name declared within the same scope, and to
> > reuse that register (after emptying it) would be a solution to the
> > problem. [...]
> 
> You cannot do that. Inner functions may still use the first variable,
> even if its name is shadowed.

Although only if such functions are defined between declarations.  Are
there any other cases, other than functions, that lock such variables?

> 
> > [...] having a spare register for some more locals, should you need
> > them.
> 
> Have you ever needed more registers than the compiler provides?

I've not, but I have certainly seen people complain about hitting the
limit before.  The issue for me is how these values are essentially
leaked in some circumstances.

B.