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Postings from November 2004
At 5:53 PM +0100 11/13/04, Leopold Toetsch wrote:
>As the analysis of test errors of the new reigster allocator has
>shown, we have a problem WRT register allocation. This problem isn't
>new, but as the allocator is more efficiently reusing registers (or
>reusing them in a different way) it's exposed again.
We don't really have that much of a problem. What we have is just
something more simple -- the target of a continuation marks the start
of a basic block. That means that we have to assume everything we
don't get handed back from the function's dirty and should be
refetched.
Or, alternately, if we declare that the top half of the register set
is preserved on function call and return we can assume that the PMCs
and values in there are acceptable for use, though any that map to
lexicals or globals ought to be refetched, since we have the
possibility that the names have been rebound.
I'm perfectly fine in declaring that this is *only* legitimate in
mainline code, and that code generators don't have to deal with the
possibility that vtable or MMD function code has rebound names.
--
Dan
--------------------------------------it's like this-------------------
Dan Sugalski even samurai
dan@sidhe.org have teddy bears and even
teddy bears get drunk
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