Re: backend question

"Fergus Henderson" <fjh@students.cs.mu.OZ.AU> writes:
|> "Nick Maclaren" <nmm1@cus.cam.ac.uk> writes:
|> >Fergus Henderson <fjh@cs.mu.OZ.AU> wrote:
|> >>"David Chase" <chase@world.std.com> writes:
|> >>
|> >>>Standard C doesn't give you enough control to write a precise garbage
|> >>>collector (one that can see all the pointers, and exactly all the
|> >>>pointers),
|> >>
|> >>It does (albeit with a potentially significant performance cost).
|> >>See my recent paper at ISMM'02 [1].
|> >
|> >Well, I have looked at it but can't say that I have studied it. I
|> >think that you have assumed quite a few extra constraints - mainly of
|> >the form that the C program is half sane!
|>
|> Certainly. But we were talking about using C as a target language.
|> For that case, the high-level language compiler has complete control
|> over what C code is generated.


Then I am puzzled by the original remarks. Any general purpose
language can be used in that way - Fortran II and 66 were, heavily.
As with mathematical Turing machines, any general purpose language can
be compiled into any other, with some niggles about details.


The only question is how many of the features have to be emulated,
which affects the overheads.


|> Note that even assembler doesn't give you enough control to write a
|> precise garbage collector that will work for arbitrary assembler programs!
|> So C is no worse than assembler in that respect.


Agreed.




Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email: nmm1@cam.ac.uk
Tel.: +44 1223 334761 Fax: +44 1223 334679

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