rust-lang/llvm — pull request #4 by neykov (2014-02-19 21:03:22+00:00)
Title: Add stack overflow check for ARM Thumb instruction set.

Besides the mechanical changes between the ARM and Thumb functions,
because of the different instruction sets, there is difference in how the
stack limit is located. The ARM version uses hardware which isn't available
on the lower-end Thumb processors (namely system co-processor and MMU)
therefore the stack limit is placed at a predefined location in
memory - STACK_LIMIT. It is the responsibility of the wrapping runtime
to manage this location with the correct value. It can vary from a simple
constant defined by the linker to actively managed variable by a RTOS
implementation.