Re: [PATCH] CTF as a fallback when no DWARF debug info is present

[Dodji Seketeli <dodji@seketeli.org>]

Hey again Guillermo,

So, even before you sent the patch, I was "playing" with the idea of
re-organizing the code of the readers to make front-ends/readers be
first class citizens in libabigail.

The idea is to have all the front-ends share/implement an abstract
interface: the Front End Interface, named abigail::fe_iface.  So there
would be abigail::elf_reader::reader, abigail::dwarf_reader::reader and
abigail::ctf_reader::reader and abigtail::abixml_reader::reader
front-ends, all implementing the abigail::fe_iface.  They would all have
to grok their intended input, build the IR as a result and pass it to
the middle-end.

Most of the craft of analyzing the ELF part would be of course in
located in the abigail::elf_reader::reader type.

The abigail::{dwarf,ctf}_reader::reader types would just have to use the
elf_reader::reader type to handle ELF stuff.

An example of what that would look like is in the
"users/dodji/front-end" branch at
https://sourceware.org/git/?p=libabigail.git;a=shortlog;h=refs/heads/users/dodji/front-end.

The interface of the new elf-reader type is at
https://sourceware.org/git/?p=libabigail.git;a=blob;f=include/abg-elf-reader.h;hb=refs/heads/users/dodji/front-end.

The abigail::fe_iface interface it implements is at
https://sourceware.org/git/?p=libabigail.git;a=blob;f=include/abg-fe-iface.h;hb=refs/heads/users/dodji/front-end.

It's not yet documented, but after the discussion we had on your patch,
I tried to implement a helper function
abigail::tools_utils::file_has_dwarf_debug_info() using the new
abigail::elf_reader::reader type.

You can see it at
https://sourceware.org/git/?p=libabigail.git;a=blob;f=src/abg-tools-utils.cc;hb=refs/heads/users/dodji/front-end#l423

So, that function file_has_dwarf_debug_info() can be used to determine
if an ELF file has debug info (even taking into account split debug
information).  Based on that information, the tool could chose the right
front-end to use.

This is still work-in-progress, but the branch passes "make distcheck",
for what it's worth.

If you are interested, maybe you could base the subsequent versions of
your patch on this branch?  What do you think?

In any case, I'll keep exploring this topic on that branch and I'll send
a message to the list a bit later to present it a little bit further.

Cheers,

-- 
		Dodji