Or if you are writing a compiler (or similar code generator, such as a sort compare generator, or a SQL implementation). One instruction saved X a million compiles = a million instructions saved. Some of us here do things of that type.
Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of John McKown Sent: Monday, February 17, 2014 10:09 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Branch (was: Performance question - adding) On Mon, Feb 17, 2014 at 12:03 PM, Paul Gilmartin <paulgboul...@aim.com>wrote: > On 2014-02-17, at 10:36, Ted MacNEIL wrote: > > > I have to ask: Why they big concern over a few instructions? > > Optimisation of a few is not worth > > the > effort these days. > > > Hmmm... No single instruction is worth optimizing. > > No single instruction among a million is worth optimizing. > > It's not worth optimising a million instructions because that would > imply optimizing each, which is not worth it. > > E.E. asked whether the code is in a loop. > > -- gil > > I guess that I ASSuMEd that the code was in a heavily used loop. If you remove 1 instruction from a loop which is executed a million times, assuming the instruction is "expensive", then it may well be worth the effort. Or maybe even replacing it with two "simpler" instructions (such as my thought on using IPM and SPM with an STOC instead of a JZ and ST). ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
