On 2021-03-12 00:41, Peter Relson wrote:
To add to what Charles M posted,
Don't forget that LA in AMODE 31 always zeroes bit 32, and LA in AMODE
24
zeroes bits 32-39 of the 64-bit GR.
That's another way that they are not functionally equivalent, if that
difference matters to you.
A good rule of thumb is that when you have equivalent alternatives,
choose
the one that has the smallest instruction byte footprint.
BCTR is a 2 byte instruction. But don't sacrifice the readability of
your
code.
If it's readability you want, do a macro DECR.
But BCTR has been in use since ... 1965 or so,
that's 55 years, so it' likely that people will
know what it does by now.
