I believe you are right. I did a bit of archeology, but could not
find the purpose of this undef.
Before you added the '#define CALL_DUMMY_LOCATION ON_STACK' when you
changed the default value for CALL_DUMMY_LOCATION, there was no such
defined in tm-hppa.h... So the undef was useless, and now seems to
cause some breakage on hppa64.
Short of understanding completely the issues at hand, I simply ran the
testsuite with and without the #undef, and found that that results are
sensibly better without (ie, to my relief, you guess right about hppa64).
I have the following change ready:
2003-01-28 J. Brobecker <brobecker@gnat.com>
* config/pa/tm-hppa64.h (CALL_DUMMY_LOCATION): Remove #undef
causing some regressions due to a change in the default value
for this macro.