Support cross compiling to BSD and CI it
(cherry picked from commit 1f3fc08c5994ca69c84c9e745d59ec2bb2fd820a)
Change-Id: I415e92952afc661cfb5ef91a76c0637678a04a19
It is still necessary.
Please do your research, or f ask the author, which happens to be me.
An evaluator like this is not an environment where "it compiles, so
it works" will ever hold.
This reverts commit 1c40182b12.
The darwin_stop_world implementation is slightly different. sp goes to
altstack_lo instead of lo in this case. Assuming that is an
implementation detail.
But the fix is the same, when we detect alstack_lo outside of the
expected stack range, we reset it to hi - stack_limit.
Here stack_limit is calculated with pthread_get_stacksize_np since
that is the BSD equivalent to pthread_attr_getstacksize.
Fixes the problem where a stack pointer outside the original
thread causes the collector to crash.
It could be made more accurate by recording the stack pointer
every time we switch to a coroutine. We can use this information
to update our own coroutine stacks like normal data. When the
stack pointer is on a thread, we can add a field to GC_thread
"fallback_sp" to be used when the thread sp is outside the original
thread range.
