Well what you say about the assembler list makes a certain amount of sense, but I would assert that it is not actually an assembler question -- the question would be equally relevant if I were a masochist coding in machine language or were writing a compiler -- it has nothing to do with the assembler.
In any event, others (and the excellent link below) answered my question. It certainly seemed reasonable to me that a CPU could tell the difference between BCTR Rn,0 and BCTR Rn,not_zero but I thought I had heard the opposite somewhere. Thanks all. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Edward Jaffe Sent: Monday, October 23, 2006 9:54 AM To: [email protected] Subject: Re: BCTR out of favor? Charles Mills wrote: > Do I recall correctly hearing that BCTR Rn,0 is no longer the favored way of > decrementing a register, perhaps because the cache logic sees it as a > potential branch, and that AHI Rn,-1 should be substituted? > > Similarly, that AHI is preferable to LA for adding a small increment to a > register, perhaps because LA may invoke or "reserve" the address translation > logic? > Wrong forum. You'd be much better off bringing up this sort of topic on ASSEMBLER-LIST. I suggest you peruse Dave Bond's excellent presentation from SHARE in Baltimore as well as the papers and presentations referenced therein: http://shareew.prod.web.sba.com/client_files/callpapers/attach/SHARE_in_Balt imore/S8192DB073718.pdf ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
