crasher in dwarf2loc.c

[Michael Snyder]

Hey Daniel, 

I've got a core dump coming from dwarf_expr_frame_base.
First you call get_frame_function, and then you immediately
use its return value.  But get_frame_function can return zero, 
so I think you need to check for zero before using it.

Michael

PS: more details:  get_frame_block returns zero, because
frame_address_in_block returns a pc that is not in any block.

The crash occurs while running recurse.exp, when we have a
watchpoint on a local variable in an inner frame, and we 
continue -- so I don't know the exact context; but I'm 
willing to bet that it is trying to evaluate the local
variable after the stack frame has been destroyed.