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

["Guillermo E. Martinez" <guillermo.e.martinez@oracle.com>]

On 10/6/22 09:12, Dodji Seketeli wrote:
> 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.
> 

Ohh, cool.

> 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.
> 

OK, perfect!.

> 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.
> 

OK.

> 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.
> 

Perfect!.

> 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?
> 

Totally agree.

> 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.
> 

Thanks!.

> Cheers,
>