Re: Register allocation patent

stevec@pact.srf.ac.uk (Stephen Clarke) writes:
>What is the status of IBM's patent on register allocation and spilling
>via graph coloring? Most people seem to reference Chaitin's work when
>describing their register allocators, including numerous commercial
>companies; is the patent unenforceable?


Well, it's still a patent and I would imagine IBM can enforce it. But
recall that the existence of a patent doesn't prohibit anyone using
the technique; instead, it means that commercial users need to obtain
a license.


Also, technical papers have to include adequate bibliographies and
comparisons with other work. When I see a paper on register
allocation, a question I want answered is: "How does this compare to
Chaitin's work?" So you'll see lots of papers that reference Chaitin,
even if only to say "We're not at all like Chaitin!"


Preston Briggs
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