FWIW,
If the "branch technique" is faster, and depending on how high a
percentage "most of the time" (as in "most of the time CURRENT will be
zero") is, then the branch technique given as the alternative to no-branch
is likely not optimal. Even with branch prediction technology, it is still
better to have the "expected path" not take a branch.
So, for example (when LT is available),
LT Rx,CURRENT
JNZ Need_To_Add
Return_From_Need_To_Add DS 0H
...
Need_To_Add DS 0H
A Rx,SUM
ST Rx,SUM
J Return_From_Need_To_Add
Then you get to factor in how much "readability" is worth to you.
Peter Relson
z/OS Core Technology Design
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