[PATCH] PR18399: Fix a bug-in Thumb1 on Folding SP Update

[Tim Northover]

Hi Zhaoshi,

> Please see http://llvm.org/bugs/show_bug.cgi?id=18399.

Thanks for working on this patch. It looks good to me, though could
you add an assert that the instruction found really is a tBX_LR? After
that, I think you should just commit it.

Cheers.

Tim.