Re: remote dwarf info using libunwind

[Wu Zhou <woodzltc at cn dot ibm dot com>]

Alexandre Oliva wrote:
> Here's the patch I've just completed, that works on x86, and fixes a
> potential libunwind memory leak while at that.
>
> As it turns out, libunwind already has all that we need, we were just
> missing the proper way to use it.  dwarf_find_proc_info() was not it,
> since it's specifically designed to operate on the local process.
> Part of the libunwind-ptrace interface offers access to everything we
> need as far as locating unwind tables et al is concerned, while still
> using our own callbacks to interact with the process using ptrace or
> whatever.  

I am not sure too why we didn't use libunwind-ptrace.a directly before.  One reason might be that it 
is not really a part of libunwind API.  But my point is, as long as it is general enough, why can't 
we make it part of libunwind API?

> I'm not sure why we don't just bite the bullet and use all
> of the libunwind interface (it looks like it would be much simpler and
> would get us what we want), but I figured I wouldn't remove any such
> code for now.

> +
> +void
> +lib::unwind::StackTraceCreator::unwind_destroy (unwargs *args)
> +{
> +	unw_destroy_addr_space ((unw_addr_space_t)args->unwas);
> +	args->unwas = 0;
> +	_UPT_destroy ((void*)args->UPTarg);
> +	args->UPTarg = 0;
> +}

This should be unwind_finish, I guess.  There is no member function named unwind_destroy in 
lib/unwind/StackTraceCreator.java, there is a member named unwind_finish instead.

Regards
- Wu Zhou