Article View: comp.arch
Article #22503Re: 64-bit addresses
From: Robert Firth
Date: Wed, 21 Feb 1990 19:07
Date: Wed, 21 Feb 1990 19:07
18 lines
1246 bytes
1246 bytes
In article <2054@osc.COM> jgk@osc.osc.COM (Joe Keane) writes:
>I agree this [ pooling constants]
is hard, but it's an interesting optimization and can only
>improve your performance. Of course it's completely impossible if your
>constants are embedded in the instruction stream.
Sorry, I don't see that. Since the average constant is smaller than
the average address, taking constants out of line and pooling them
seems to me a guaranteed pessimisation
(a) you don't save bits in the instruction, and may need more
(b) the extra indirection is one more memory reference, which
is pure overhead
(c) you have reduced locality by adding a gratuitous reference to
another part of the address space
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!tut.cis.ohio-state.edu!pt.cs.cmu.edu!sei!firth From: firth@sei.cmu.edu (Robert Firth) Newsgroups: comp.arch Subject: Re: 64-bit addresses Message-ID: <6190@bd.sei.cmu.edu> Date: 21 Feb 90 19:07:52 GMT References: <9708@spool.cs.wisc.edu> <20270@cfctech.cfc.com> <11112@encore.Encore.COM> <10795@snow-white.udel.EDU> <2027@osc.COM> <162@gollum.twg.com> <2054@osc.COM> Reply-To: firth@sei.cmu.edu (Robert Firth) Organization: Software Engineering Institute, Pittsburgh, PA Lines: 18