On what machine? Things done to speed up the code on one processor can slow it down on another. I'd go for what is most readable, or encapsulate it in a macro that generated different code for different boxen.
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Assembler List <[email protected]> on behalf of Schmitt, Michael <[email protected]> Sent: Monday, August 10, 2020 3:12 PM To: [email protected] Subject: Clearing a register There are many ways to set a register to binary zero. My question is, which is the most efficient? 1. XR Rn,Rn 2. SR Rn,RN 3. SRA Rn,Rn 4. LHI Rn,0 5. Other instruction 6. Depends on hardware 7. Depends on other factors. (What?) 8. They are have equal performance 9. Method X has worse performance but other advantages. (What?) ____________________________________ Michael Schmitt | DXC.technology (469) 808-4403 | [email protected] DXC Technology Company - Headquarters: 1775 Tysons Boulevard, Tysons, Virginia 22102, USA. DXC Technology Company -- This message is transmitted to you by or on behalf of DXC Technology Company or one of its affiliates. It is intended exclusively for the addressee. The substance of this message, along with any attachments, may contain proprietary, confidential or privileged information or information that is otherwise legally exempt from disclosure. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient of this message, you are not authorized to read, print, retain, copy or disseminate any part of this message. If you have received this message in error, please destroy and delete all copies and notify the sender by return e-mail. Regardless of content, this e-mail shall not operate to bind DXC Technology Company or any of its affiliates to any order or other contract unless pursuant to explicit written agreement or government initiative expressly permitting the use of e-mail for such purpose. --.
