> -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On > Behalf Of Joel Wolpert > Sent: Friday, August 07, 2009 5:42 PM > To: [email protected] > Subject: Re: z10 and overlapping/destructive moves > > Just curiously. Why do you call this an overlapping/destructive move.
That's what the PoOP calls it when discussing MVCL and why you can't do this with MVCL, only with MVC. >From the MVCL section: "As part of the execution of the instruction, the values of the two length fields are compared for the setting of the condition code, and a check is made for destructive overlap of the operands. Operands are said to overlap destructively when the first-operand location is used as a source after data has been moved into it, assuming the inspection for overlap is performed by the use of logical operand addresses. When the operands overlap destructively, no movement takes place, and condition code 3 is set." > ----- Original Message ----- > From: "Farley, Peter x23353" <[email protected]> > Newsgroups: bit.listserv.ibm-main > To: <[email protected]> > Sent: Friday, August 07, 2009 3:49 PM > Subject: z10 and overlapping/destructive moves > > > >I am in the midst of a CPU optimization exercise for a COBOL program and > > ran across the following code sequence generated by the compiler: > > > > MVI 254(3),X'40' > > MVC 255(119,3),254(3) > > > > This code is generated in response to a simple COBOL "MOVE SPACES TO > > variable" instruction, where the variable is 120 bytes long. This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. ---------------------------------------------------------------------- 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
