Re: Ada GC (was about Java VM)

Hans Boehm <boehm@parc.xerox.com> wrote:
>Based on measurements by Vincent Delacour, type information would help
>more if you could also know that non-nil pointers always point to the
>garbage collected heap (as might be true in an Ada implementation).


Actually, Ada 95 allows pointers into the stack. However any variable
that might be pointed at in that way has to be explicitly declared
"aliased". So it might make sense for aliased variables to have extra
garbage-collection dope.


>But this isn't free. It typically forces significant numbers of
>constants, etc. to be copied to the heap, solely to preserve this
>invariant.


Why copy them to the heap? Why not just mark them so they are
recognizable at run time?


>And one more nit: Ada is type secure only in the absence of explicit
>deallocation.


Yes, and a bunch of other low-level features!


- Bob
--

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