Re: What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" instruction?
On Fri, 26 Jul 2019 at 08:52, Mike Schwab wrote: > Well, the hardware does move a 256 byte area aligned on a 256 bytes > boundary very efficiently. And would allow you to load the register > with an address without storing the last byte. So a storage pool with > allocation of multiples of 256 bytes would greatly helped. > I thought of that... But then for generality maybe the instruction should be something like Load and Zero Rightmost Sufficient-to-address-a-cache-line Bits. Tony H. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" instruction?
Take some (any) big C or COBOL program and run it through the relevant compiler with the pseudo-assembler output option turned on, OPT and ARCH(9 or 10). Then do an ISPF FIND for the op code. No guarantees of course. Charles -Original Message- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Peter Relson Sent: Thursday, July 25, 2019 5:04 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" instruction? I don't know the answer, but the usual answer is: because either the Java team or the compiler team found something beneficial to having it. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" instruction?
Well, the hardware does move a 256 byte area aligned on a 256 bytes boundary very efficiently. And would allow you to load the register with an address without storing the last byte. So a storage pool with allocation of multiples of 256 bytes would greatly helped. On Thu, Jul 25, 2019 at 10:53 PM Phil Smith III wrote: > > Peter Relson wrote: > > >I don't know the answer, but the usual answer is: > > >because either the Java team or the compiler team found something > > >beneficial to having it. > > > > Which leads one to wonder.at what point does the C in CISC make this a losing > proposition? Are we there yet? > > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" instruction?
Peter Relson wrote: >I don't know the answer, but the usual answer is: >because either the Java team or the compiler team found something >beneficial to having it. Which leads one to wonder.at what point does the C in CISC make this a losing proposition? Are we there yet? -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" instruction?
I don't know the answer, but the usual answer is: because either the Java team or the compiler team found something beneficial to having it. Peter Relson z/OS Core Technology Design -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" instruction?
Argh. A "LOAD LOGICAL 24 BITS" would actually still be useful. Of course, we need the other 24 bits :-). LAN (and LAA) are weird instructions. The and part (AND or OR) (does this read like "Alice in Wonderland" yet?) is performed on the *second* operand -- the field in storage. They have some fairly obvious uses (similar to CS), but the names seem misleading to me. As for LZRF... maybe somebody finally got an Easter egg into the architecture. You'd think that a L / NILL sequence wouldn't likely be the worst bottleneck they needed to solve last year. sas On Wed, Jul 24, 2019 at 6:00 PM zMan wrote: > Obviously it's for little-Endian 24-bit addressing mode! > > On Wed, Jul 24, 2019 at 3:18 PM Tony Harminc wrote: > > > On Wed, 24 Jul 2019 at 08:35, Vernooij, Kees (ITOP NM) - KLM < > > kees.verno...@klm.com> wrote: > > > > > I cannot answer your question, it is probably depending on how the > > > hardware works on different machines. > > > > > > Another question: what is the purpose of this instruction? > > > > > > I think that's what the OP was asking. > > > > Is it executed that often that it is worthwhile to make an instruction to > > > replace 2 instructions (Load+AND, MOVE+AND) or is there another reason? > > > > > > > In fact there is an earlier Load and AND instruction LAN/LANG that can do > > just the same thing in one instruction, though it also sets the condition > > code based on the result, and requires full or double word alignment, > which > > LZRF/LZRG do not. > > > > Paging Dan Greiner... > > > > Tony H. > > > > -- > > For IBM-MAIN subscribe / signoff / archive access instructions, > > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > > > > > -- > zMan -- "I've got a mainframe and I'm not afraid to use it" > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > -- sas -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" instruction?
Obviously it's for little-Endian 24-bit addressing mode! On Wed, Jul 24, 2019 at 3:18 PM Tony Harminc wrote: > On Wed, 24 Jul 2019 at 08:35, Vernooij, Kees (ITOP NM) - KLM < > kees.verno...@klm.com> wrote: > > > I cannot answer your question, it is probably depending on how the > > hardware works on different machines. > > > > Another question: what is the purpose of this instruction? > > > I think that's what the OP was asking. > > Is it executed that often that it is worthwhile to make an instruction to > > replace 2 instructions (Load+AND, MOVE+AND) or is there another reason? > > > > In fact there is an earlier Load and AND instruction LAN/LANG that can do > just the same thing in one instruction, though it also sets the condition > code based on the result, and requires full or double word alignment, which > LZRF/LZRG do not. > > Paging Dan Greiner... > > Tony H. > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > -- zMan -- "I've got a mainframe and I'm not afraid to use it" -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" instruction?
On Wed, 24 Jul 2019 at 08:35, Vernooij, Kees (ITOP NM) - KLM < kees.verno...@klm.com> wrote: > I cannot answer your question, it is probably depending on how the > hardware works on different machines. > > Another question: what is the purpose of this instruction? I think that's what the OP was asking. Is it executed that often that it is worthwhile to make an instruction to > replace 2 instructions (Load+AND, MOVE+AND) or is there another reason? > In fact there is an earlier Load and AND instruction LAN/LANG that can do just the same thing in one instruction, though it also sets the condition code based on the result, and requires full or double word alignment, which LZRF/LZRG do not. Paging Dan Greiner... Tony H. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" instruction?
I cannot answer your question, it is probably depending on how the hardware works on different machines. Another question: what is the purpose of this instruction? Is it executed that often that it is worthwhile to make an instruction to replace 2 instructions (Load+AND, MOVE+AND) or is there another reason? Kees. > -Original Message- > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On > Behalf Of Jerry Callen > Sent: 24 July, 2019 14:22 > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" > instruction? > > Is it Friday yet? > > The z13 (I think) added this puppy: > > = > > LOAD AND ZERO RIGHTMOST BYTE > > The second operand, with the rightmost byte set to zero, is placed at the > first-operand location. For LZRF, the first and second operands are 32 > bits, and for LZRG, the first and second operands are 64 bits. > > The displacement is treated as a 20-bit signed binary integer. > > It is unpredictable whether an access exception is recognized for the > rightmost byte of the second operand. > > = > > Why? > > -- Jerry > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN For information, services and offers, please visit our web site: http://www.klm.com. This e-mail and any attachment may contain confidential and privileged material intended for the addressee only. If you are not the addressee, you are notified that no part of the e-mail or any attachment may be disclosed, copied or distributed, and that any other action related to this e-mail or attachment is strictly prohibited, and may be unlawful. If you have received this e-mail by error, please notify the sender immediately by return e-mail, and delete this message. Koninklijke Luchtvaart Maatschappij NV (KLM), its subsidiaries and/or its employees shall not be liable for the incorrect or incomplete transmission of this e-mail or any attachments, nor responsible for any delay in receipt. Koninklijke Luchtvaart Maatschappij N.V. (also known as KLM Royal Dutch Airlines) is registered in Amstelveen, The Netherlands, with registered number 33014286 -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
What's the intent of the "LOAD AND ZERO RIGHTMOST BYTE" instruction?
Is it Friday yet? The z13 (I think) added this puppy: = LOAD AND ZERO RIGHTMOST BYTE The second operand, with the rightmost byte set to zero, is placed at the first-operand location. For LZRF, the first and second operands are 32 bits, and for LZRG, the first and second operands are 64 bits. The displacement is treated as a 20-bit signed binary integer. It is unpredictable whether an access exception is recognized for the rightmost byte of the second operand. = Why? -- Jerry -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
