Starting with 2757acf6, the `top` variable in `nlr_jump()` in
`nlraarch64.c` was assigned to register `x19` by the compiler. However,
the assembly code writes over that register with
ldp x19, x20, [%0, #32]
since `%0` is now `x19`. This causes the next line
ldp lr, x9, [%0, #16]
to load the wrong values.
To fix the issue, we move the value of the `top` variable from an unknown
register to a known register at the beginning of the asm code then only use
known/hard-coded registers after that.
Fixes issue #11754.
Signed-off-by: David Lechner <david@pybricks.com>
The proper way to do this is to test for __APPLE__ and __MACH__, where
__APPLE__ tests for an Apple OS and __MACH__ tests that it is based on CMU
Mach. Using both tests ensures that just Darwin (Apple's open source base
for MacOS, iOS, etc.) is recognized. __APPLE__ by itself will test for any
Apple OS, which can include older OS 7-9 and any future Apple OS. __MACH__
tests for any OS based on CMU Mach, including Darwin and GNU Hurd.
Fixes#7232.
David Lechner