Got it. Assuming the J *+2 is actually JNx *+2, where 'x' is the expected condition (Z following an LTR of a return code, for example).
Charles -----Original Message----- From: IBM Mainframe Assembler List [mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU] On Behalf Of Tom Marchant Sent: Thursday, May 11, 2017 12:36 PM To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: Quick error termination of an assembler routine (Was: Performance of Decimal Floating Point Instruction) On Thu, 11 May 2017 10:44:25 -0700, Charles Mills wrote: >What is *wrong* with DC H'0'? It has the advantage of being incredibly >straightforward. I had to spend a minute thinking about J *+2; I pretty much >guarantee you anyone with six months of HLASM experience would "get" DC H'0'. I wouldn't say that anything is wrong with it. But when it is included in code for a condition that should never occur and you haven't (yet) coded a proper error routine, the instruction before it is typically a branch over it. I don't know how big the branch taken hit on the pipeline is in that case. But in the J *+2 case, the normal path is to fall through, and only take the branch under the error condition.
