The question is very much hardware dependent, and is much less relevant to
predicting performance than it might have been half a century ago.
The relevant questions are:
Do you want to clear the high bits?
Do you want to preserved the condition code?
What will be more readable to your fellow programmers?
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
________________________________________
From: IBM Mainframe Assembler List [[email protected]] on behalf
of Schmitt, Michael [[email protected]]
Sent: Wednesday, March 10, 2021 6:26 PM
To: [email protected]
Subject: Add 1, Subtract 1
I was taught long ago to add 1 to a register using LA r#,1(,r#) and to subtract
1 using BCTR r#,0.
Is the fastest way now to use AHI r#,1 and AHI r#,-1?
