On 2020-06-02, at 15:30:33, Dan Greiner wrote: > > Using the indexed branch allows for many more possible actions -- not just > binary true/false -- but may necessitate accommodating all possible branch > cases following each return. I also agree that the indexed branch approach > may be more complicated to maintain. > But the prudent programmer will test the range before branching.
> As to how to set [and preserve] the condition code, many experienced > assembler programmers have yet to discover the "newer" instruction SET > PROGRAM MASK (SPM) [and INSERT PROGRAM MASK (IPM)]. I say "newer" with > tongue pressed firmly in cheek, since these unprivileged instructions have > been around since the introduction of the S/370 (five decades ago). > Only half. I belive SPM is older; IPM appeared only with XA when BALR no longer sufficed to capture the PM. -- gil
