[PATCH] ARM and Thumb Segmented Stacks

[Alex Crichton]

> Out of curiosity, hasn't rust moved away from using segmented stacks?
> Or that was on X86 only?

We did indeed drop segmented stacks, our green tasks now use one large
stack instead of lots of little ones. We are still using the
__morestack prologue to detect stack overflow, however. For us
whenever the __morestack prologue is triggered it means that the task
has overflowed the stack and we start the task failure machinery.

We're still trying to get away from this (it's kinda overkill for what
we're doing), but for the time being it's the best solution we have
that LLVM implements.