Add _OOP_find_proc_info

[sdmaclea]

This code was added to CoreCLR as part of dotnet/coreclr#26082. I am submitting the code exactly as it was committed in dotnet/coreclr#26082. We are open to refactoring to make this fit the libunwind design.

The code was written to avoid having to reimplement libunwind's dwarf parser so that we could implement out of process unwind for arm. It also allowed us to remove dwarf parse code for other architectures.

The PR is not necessarily complete. For instance this prototype should be made available in some header.

int
_OOP_find_proc_info(
    unw_word_t start_ip,
    unw_word_t end_ip,
    unw_word_t eh_frame_table,
    unw_word_t eh_frame_table_len,
    unw_word_t exidx_frame_table,
    unw_word_t exidx_frame_table_len,
    unw_addr_space_t as,
    unw_word_t ip,
    unw_proc_info_t *pi,
    int need_unwind_info,
    void *arg);

/cc @mikem8361 @djwatson

[am11]

nit: use the libunwind header.

[djwatson]

+1 Yea if possible change to libunwind header.

[am11]

Can it be exercised with a test in this repo?

[sdmaclea]

I'll take a look at writing a test.

[djwatson]

I'm not opposed to this, but at a minimum should be part of the build and have a test.

If you think it should be a public function, should probably have some documentation too, although I'm okay letting it be undocumented.

[sdmaclea]

Sure. I'll clean this up next week.
I just finished integrating Windows libunwind into .NET Core master. It seems to be working.

[djwatson]

Closing for now, feel free to reopen with tests & build additions.