Article View: comp.lang.asm370
Article #320Re: ICM vs. L and LTR
From: Dave Andrews
Date: Thu, 13 Aug 1992 15:30
Date: Thu, 13 Aug 1992 15:30
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1681 bytes
In article <1992Aug12.163757.759@infonode.ingr.com> dwayne@dwayneb.b17d.ingr.com (Dwayne A. Blumenberg) writes: >I've noticed lately that some recent IBM code uses >the sequence: > > L Rx,AREA > LTR Rx,Rx > BNZ SOMEWHERE > >and I was wondering if > > ICM Rx,15,AREA > BNZ SOMEWHERE > >would be faster? A paper in the CME Newsletter #88 entitled "Measuring 370 Instructions" (by Ed Stewart) talks about the author's effort to measure how fast individual instructions are on a 3081K CPU. Pipelining and alignment and god knows what else all affect instruction execution rates, so IBM doesn't quote these much anymore. Anyway, he clocked the following instructions at the indicated MIPS: ICM 0,15,W1 10.4287 L 0,W1 41.8938 LTR 0,1 41.7416 So it appears that -- at least on a 3081K -- the L/LTR sequence is roughly twice as fast as the ICM. >-- >Dwayne A. Blumenberg | Internet: dwayne@dwayneb.b30.ingr.com >IBM Systems Programmer | UUCP: ...uunet!ingr!b30!dwayneb!dwayne >Intergraph Corp., M.S. GD3002 | Voice: (205) 730-3795 >Huntsville, AL 35894-0001 | FAX: (205) 730-3300 - David Andrews dandrews@bilver.oau.org
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Newsgroups: comp.lang.asm370 Path: arc1-ca.pugleaf.net!sparky!uunet!gatech!darwin.sura.net!cs.ucf.edu!tarpit!tous!bilver!dandrews From: dandrews@bilver.uucp (Dave Andrews) Subject: Re: ICM vs. L and LTR Organization: W. J. Vermillion - Winter Park, FL Date: Thu, 13 Aug 1992 15:30:01 GMT Message-ID: <1992Aug13.153001.2106@bilver.uucp> References: <1992Aug12.163757.759@infonode.ingr.com> Lines: 39