the function's prologue instructions so we can re-instate that prologue
if we hit an early return mid-function. Add some additional heuristics
to differentiate between prologue and epilogue instruction sequences.
This fixes the specific problem of correctly unwinding through a function
which has an epilogue one instruction after the last prologue setup
instruction has completed.
<rdar://problem/12091139>
llvm-svn: 166465
7cd5e831e5