[PATCH] [lbc++abi] [unwinder] Support Cortex-m0

[Saleem Abdulrasool]

Please drop `ARM_RETURN` and use `JMP(lr)`.  That is duplicating an existing macro which is already in use.

Im not sure I understand why you are creating a new macro for the thumb check.  `__ARM_ARCH_ISA_THUMB == 1` is sufficient to identify if you only have Thumb-1.  However, do you really want to use thumb instructions if you only have Thumb-1?

I dont understand the need for the `ARM_HAS_NO_VFP`.  Isn't `__VFP_FP__` usable for your check there?  I don't think we need yet another macro, particularly if there is one that is defined by the compiler.

Finally, is `__ARM_WMMX` supposed to be defined for ARMv6M/s?

http://reviews.llvm.org/D5314