The COBOL compiler for a 4000 byte move, from to the same with OPT(2) generates
LAY R10,5072(,R9) FROM LA R7,1072(,R9) TO MVC 0(256,R7),0(R10) MVC 256(256,R7),256(R10) MVC 512(256,R7),512(R10) MVC 768(256,R7),768(R10) MVC 1024(256,R7),1024(R10) MVC 1280(256,R7),1280(R10) MVC 1536(256,R7),1536(R10) MVC 1792(256,R7),1792(R10) MVC 2048(256,R7),2048(R10) MVC 2304(256,R7),2304(R10) MVC 2560(256,R7),2560(R10) MVC 2816(256,R7),2816(R10) MVC 3072(256,R7),3072(R10) MVC 3328(256,R7),3328(R10) MVC 3584(256,R7),3584(R10) MVC 3840(160,R7),3840(R10) However for 5000 bytes it generates: LAY R7,6072(,R9) LA R10,0(,R7) LA R7,1072(,R9) LHI R11,0x13 EQU * MVC 0(256,R7),0(R10) LA R10,256(,R10) LA R7,256(,R7) BRCT R11,L0128 MVC 0(136,R7),0(R10) And yes the change occurred at 4097 bytes. -----Original Message----- From: IBM Mainframe Assembler List <ASSEMBLER-LIST@LISTSERV.UGA.EDU> On Behalf Of Charles Mills Sent: Tuesday, October 20, 2020 10:54 To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: Conditional MVCL macro? @Ed, can you elaborate a little on your reasoning? (Not doubting it; just curious.) Is it that the interruptibility provides a significant improvement over MVCL? Or the support for lengths greater than 16M? Or ... ? When I asked Dr. Shum about move strategies he seemed to indicate that for data that was already or would soon anyway be in cache an MVC loop was generally faster than MVCL. (I did not ask about MVCLE at the time; not sure why. He did not suggest it.) Charles -----Original Message----- From: IBM Mainframe Assembler List [mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU] On Behalf Of Ed Jaffe Sent: Tuesday, October 20, 2020 6:52 AM To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: Conditional MVCL macro? We've switched almost exclusively to MVCLE except for short, fixed-length moves.
