While the GC should work on MacOS X Server, MacOS X and Darwin, I only tested
it on MacOS X Server.
I've added a PPC assembly version of GC_push_regs(), thus the setjmp() hack is
no longer necessary. Incremental collection is supported via mprotect/signal.
The current solution isn't really optimal because the signal handler must decode
the faulting PPC machine instruction in order to find the correct heap address.
Further, it must poke around in the register state which the kernel saved away
in some obscure register state structure before it calls the signal handler -
needless to say the layout of this structure is no where documented.
Threads and dynamic libraries are not yet supported (adding dynamic library
support via the low-level dyld API shouldn't be that hard).

The original MacOS X port was brought to you by Andrew Stone.


June, 1 2000

Dietmar Planitzer
dave.pl@ping.at

Note from Andrew Begel:

One more fix to enable gc.a to link successfully into a shared library for
MacOS X. You have to add -fno-common to the CFLAGS in the Makefile. MacOSX
disallows common symbols in anything that eventually finds its way into a
shared library. (I don't completely understand why, but -fno-common seems to
work and doesn't mess up the garbage collector's functionality).