On 6/13/2016 11:18 AM, Charles Mills wrote:
Does that mean that for standard "old-fashioned" AMODE 31 72-byte savearea
linkage I am obligated to save the high word of R1 before issuing LINK in a
called program? If so, this would seem to be a compatibility issue for older
code that uses LINK. Or is R1 fair game as a work register in a called
The fine manual states-
Upon return to the caller, the GPRs contain whatever values the
called program placed there.
So it all depends on how the 'interface' to the LINK'd to program is
defined. If R1 is unpredictable on return then use the high half as you
wish. If R1 defined as unchanged or returns a 32 bit value you need to
save and restore the high half.
Greg
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