[PATCH] Generate better location ranges for some register-described variables.

[Alexey Samsonov]

Yeah, well, we can add "FrameTeardown" machine instruction flag in addition to "FrameSetup", and annotate machine instructions added in frame lowering code. But do we expect many users of this flag (assuming that this usage is also somewhat questionable)?

I can also make this patch even less general and just special-case the frame pointer and the stack pointer registers, so that the code wouldn't pretend to solve a general problem we're facing.

http://reviews.llvm.org/D3933