Related articles |
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Register allocation patent stevec@pact.srf.ac.uk (1995-11-27) |
Re: Register allocation patent preston@tera.com (1995-11-28) |
Re: Register allocation patent burley@cygnus.com (1995-11-29) |
Re: Register allocation patent wilken@garlic.ece.ucdavis.edu (1995-11-29) |
Re: Register allocation patent wills@rchland.ibm.com (1995-11-30) |
Register allocation patent preston@tera.com (1995-12-09) |
Newsgroups: | comp.compilers |
From: | wills@rchland.ibm.com (William Schmidt) |
Keywords: | registers, optimize, legal |
Organization: | IBM Rochester MN |
References: | 95-11-214 |
Date: | Thu, 30 Nov 1995 20:23:58 GMT |
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?
|>
No, the patent is in full force. The state of intellectual property in the
computer world is that almost all of the major companies have signed
cross-license agreements with one another, allowing each to use the other's
patented intellectual property. If a company markets a compiler that
uses Chaitin's technique, and that company does not have an agreement with
IBM to use the technique, this is a violation of U.S. patent law.
Incidentally, thanks to Preston Briggs, Rice University owns a dependent
patent covering Briggs's optimistic coloring heuristics (modifications to the
Chaitin technique). A company using his extensions needs to have an agreement
in place with Rice.
I know all this because I accidentally ran across the Rice patent a year ago,
and had to spend some time with IP attorneys determining whether we had the
appropriate agreement with Rice. (We did; the optimistic coloring work was
done partially with funding support from IBM.)
--
William Schmidt (507) 253-0852 t/l 553-0852
GZA/030-2 wills@rchland.ibm.com (internal)
IBM Rochester wjs@vnet.ibm.com (external)
--
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