Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!watcgl!watmum!smvorkoetter From: smvorkoetter@watmum.UUCP Newsgroups: comp.lang.c Subject: Re: Dhrystones Message-ID: <2617@watcgl.waterloo.edu> Date: Mon, 7-Dec-87 10:17:18 EST Article-I.D.: watcgl.2617 Posted: Mon Dec 7 10:17:18 1987 Date-Received: Sat, 12-Dec-87 09:12:35 EST References: <3368@rosevax.Rosemount.COM> <5096@ccv.bbn.COM> <19425@amdcad.AMD.COM> <9613@mimsy.UUCP> <19440@amdcad.AMD.COM> Sender: daemon@watcgl.waterloo.edu Reply-To: smvorkoetter@watmum.waterloo.edu (Stefan M. Vorkoetter) Organization: U. of Waterloo, Ontario Lines: 17 Keywords: C, performance, useful In article <19440@amdcad.AMD.COM> tim@amdcad.UUCP (Tim Olson) writes: )In article <9613@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes: )| In article <19425@amdcad.AMD.COM> tim@amdcad.AMD.COM (Tim Olson) writes: )| >... There exists quite a lot of "dead code" in Dhrystone )| >(expressions which aren't ever used) which good compilers can optimize )| >totally away. This isn't the case with real-world code. ) ) IntLoc3 = IntLoc2 * IntLoc1; ) 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 ;-) ) ) -- Tim Olson The first IntLoc2 assignment and the division must be done since the result is used to calculate the value for the second assignment.