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From: tim@proton.amd.com (Tim Olson)
Newsgroups: comp.arch
Subject: Re: loop unrolling (was:Re: Register Count)
Message-ID: <1991Jan23.154727.26972@mozart.amd.com>
Date: 23 Jan 91 15:47:27 GMT
References: <PCG.91Jan19120851@odin.cs.aber.ac.uk> <48303@apple.Apple.COM> <PCG.91Jan22172644@odin.cs.aber.ac.uk>
Sender: usenet@mozart.amd.com (Usenet News)
Reply-To: tim@amd.com (Tim Olson)
Organization: Advanced Micro Devices, Austin, TX
Lines: 18

In article <PCG.91Jan22172644@odin.cs.aber.ac.uk> pcg@cs.aber.ac.uk (Piercarlo Grandi) writes:
| I can only say that it is hard for me to imagine, not being an hardware
| designer, relevant cases where the register file is not in the critical
| path or does not influence it. I'd like the opinion of someone who has
| dealt firsthand with this kind of issue. I think that if there are
| relevant cases, they could teach us something.

Register file access is not on the most critical path in the Am29000
(and we have 192 3-ported registers!).  Usually cache lookups and TLB
matching tend to be more critical, because they involve an immediate
comparison of tags after the access, and the arrays are usually larger
than register file arrays.


--
	-- Tim Olson
	Advanced Micro Devices
	(tim@amd.com)