> -----Original Message----- > From: IBM Mainframe Assembler List > [mailto:[email protected]] On Behalf Of john gilmore > Sent: Thursday, October 07, 2010 10:52 PM > To: [email protected] > Subject: Re: 16 bytes the same <Snipped> > Apart from its obvious usefulness in processing right-to-left > text like that of Arabic, Farsi, and Hebrew, the TRTR > instruction is valuable for locating the rightmost non-blank > character in left-to-right text.
Useful, yes. CPU efficient, not. During an application-level MIPS reduction project in the recent past I had the opportunity to measure (on a z10) finding the rightmost non-blank using TRTR against loops of CLC's of various sizes and against a CLI loop, and IIRC the CLC's almost always beat the TRTR for average CPU consumed. I think that the CLI loop was more expensive than the TRTR, especially for longer spans of blanks (>1000), but I may be mis-remembering that measurement. I did not measure TRTR against alternate algorithms using 4-byte or 8-byte register-to-storage compares. Unfortunately I don't have the numbers any more so I can't offer you any positive proof. If I find any round tuits I will try to replicate those tests, but don't hold your breath waiting for me. It will be quite interesting to see if the z196 has changed that comparison in any way. Peter -- 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.
