[PATCH 5/5] libdwfl: add interface for evaluating DWARF expressions in a frame

[Mark Wielaard]

Hi Omar,

On Mon, 2019-10-07 at 02:05 -0700, Omar Sandoval wrote:
> libdwfl can evaluate DWARF expressions in order to unwind the stack,
> but this functionality isn't exposed to clients of the library. Now that
> the pieces are in place, add dwfl_frame_eval_expr to provide this feature.

I think this is useful. But same issue as the previous patch that I am
not sure the error handling is correct for state->frame == NULL.

Also this could really use some examples and maybe a small testcase. 

That would show how to handle DWARF expressions to are simple location
descriptions (which calculate a location where a value can be found)
versus implicit location descriptions (e.g. DW_OP_value) versus
composite location descriptions (e.g. DW_OP_piece).

It might be that we don't care, because all we care about is whether or
not we can get a value, but it would validate the interface.

Having some examples/testcases would also show how/where to get the
DWARF expressions to use with this new function.

Thanks,

Mark