On 2020-06-02, at 15:53:34, Keven wrote: > > Are you suggesting the use SPM/IPM as an alternative to setting the > actual condition code? > K3n > I opposed it; its proponent outranked me.
> On Tue, Jun 2, 2020 at 4:45 PM -0500, "Paul Gilmartin" > > 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
