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- Newsgroups: comp.arch
- Message-ID: <4f=QdEW00jei0dLvEO@cs.cmu.edu>
- Date: Tue, 15 Dec 1992 07:06:40 -0500
- From: William.Lott@cs.cmu.edu
- Subject: Re: Any use for Branch if Even/Odd ?
- In-Reply-To: <endecotp.723992157@cs.man.ac.uk>
- References: <endecotp.723992157@cs.man.ac.uk>
- Lines: 13
-
- endecotp@cs.man.ac.uk (Phil Endecott) writes:
- > Can anyone think of a use for the branch if even and branch if odd
- > instructions on the Alpha? I'm completely baffled.
- >
- > --Phil.
-
- In our lisp system all pointers have the low bit 1 and all
- non-pointers have the low bit 0. So if your compiler can figure out
- that it can use this instruction to handle ``if (obj & 1) ...'' then
- our garbage collector might be a wee bit faster.
-
- -William Lott
- CMU Common Lisp Group
-