The difference, if any, should be in the cache loading. In practice. if I have to set up multiple base registers then I would wrap everything in a macro, using LAY if there were only two base registers. For 3 or more I'd use LHI to load the last with 4096 and use LA for the second through last. Of course, 2048 works just as well.
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 עַם יִשְׂרָאֵל חַי ________________________________________ From: IBM Mainframe Discussion List <[email protected]> on behalf of Tony Harminc <[email protected]> Sent: Friday, November 10, 2023 3:17 PM To: [email protected] Subject: Re: LA vs LHI On Fri, 10 Nov 2023 at 08:27, Seymour J Metz <[email protected]> wrote: > I know that it's model dependent and also depends on the cache loading, > but are there cases where there is a measurable performance difference > between these? > > LAY Rx,4096 > LHI Rx,4096 > It seems highly implausible to me that there'd be any difference. Surely the LAY case of base and index register = 0 are special cased, and there need be no waiting for the actual value of R0 to settle. A case I find a bit more interesting is setting up the typical second base register. LAY Rx,4096(,Ry) ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
