Are you suggesting the use SPM/IPM as an alternative to setting the
actual condition code?
K3n
On Tue, Jun 2, 2020 at 4:45 PM -0500, "Paul Gilmartin"
<[email protected]> wrote:
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
