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From: tim@amdcad.AMD.COM (Tim Olson)
Newsgroups: comp.lang.c
Subject: Re: Dhrystones
Message-ID: <19488@amdcad.AMD.COM>
Date: Wed, 31-Dec-69 18:59:59 EST
Article-I.D.: amdcad.19488
Posted: Wed Dec 31 18:59:59 1969
Date-Received: Sun, 13-Dec-87 11:47:44 EST
References: <3368@rosevax.Rosemount.COM> <5096@ccv.bbn.COM> <19425@amdcad.AMD.COM> <9613@mimsy.UUCP> <19440@amdcad.AMD.COM> <2617@watcgl.waterloo.edu>
Reply-To: tim@amdcad.UUCP (Tim Olson)
Organization: Advanced Micro Devices
Lines: 21
Keywords: C, performance, useful

In article <2617@watcgl.waterloo.edu> smvorkoetter@watmum.waterloo.edu (Stefan M. Vorkoetter) writes:
| In article <19440@amdcad.AMD.COM> tim@amdcad.UUCP (Tim Olson) writes:
| )		IntLoc2 = IntLoc3 / IntLoc1;
| )		IntLoc2 = 7 * (IntLoc3 - IntLoc2) - IntLoc1;
| )
| )The first assignment into IntLoc2 is replaced in the next expression --
| )no need to calculate it (and we take a divide out of the loop -- big win ;-)
| )
| The first IntLoc2 assignment and the division must be done since the result is
| used to calculate the value for the second assignment.

Sorry.  I noticed that neither expression generated code, and didn't
notice the use of IntLoc2 in the second expression.  What *really*
happened is that the compiler determined that the second expression was
dead code, which *then* made the first expression dead.

Thanks for catching that.

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