That's what the book says -- except for unconditional branches, BCT and BXLE (and the relative and G variants) which predicts a branch.
-----Original Message----- From: IBM Mainframe Assembler List [mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU] On Behalf Of Tony Thigpen Sent: 16 May 2017 14:44 To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: Quick error termination of an assembler routine (Was: Performance of Decimal Floating Point Instruction) Peter, I never have gotten a handle on "branch prediction" within the i-cache discussion. Are you saying that, for the most part, we should always try to code so that the normal path is to not-branch wherever possible? (I know, within limits.) Tony Thigpen Peter Relson wrote on 05/16/2017 08:31 AM: > <snip> > Well, in reality you are right of course (who cares about the > i-cache?) but in theory one is branching around and NOT crashing, so > not wasting the i-cache is a desirable goal. > </snip> > > A program coded with any thought for performance would not be > "branching around and NOT crashing". It would be branching out of line > upon detecting the error so that the normal path takes no branch at all. > > Thus instead of "BZ NOERROR" (or JZ or whatever), "BNZ ERROR". > > Peter Relson > z/OS Core Technology Design > > --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
