Re: [PATCH 1/3] gdb/ctf: don't create a buildsym_compunit when building partial symbols

[Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>]

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> A CTF archive contains conflicting type info and is treated as a CU.
> Since one can't switch scope among CUs in CTF, not reading archives
> might not be a problem. Please go ahead and make the change. It can
> be revisited when we come up a test case that shows otherwise.
> 
> Thanks.

Hi Wei-Min,

I'm not sure we are on the same page.  I don't know much about CTF, so
let's make sure I understand things right.  I am not sure how CTF debug
info is organized, and in particular what an "archive" is.  If you can
explain this or give a reference, that would be useful.

I'll attach the output of "readelf --ctf=.ctf" for the file I am working
with.

My understanding from the readelf output is that there is some debug
info (function, types, etc) described at the top-level.  It doesn't seem
associated to a source file, and it seems to contain things that are
global.

Then there is one "archive" for each compiled .c file, such as:

  CTF archive member: /home/simark/src/babeltrace/src/lib/current-thread.c:

Each archive contains very little data, my guess is that it only
contains what is not already described at the top-level?

Right now, in GDB, we create one CU (partial_symtab, and then
compunit_symtab after expansion) for the top-level, and the one CU for
each archive.  My patch does not change that.  It only removes a
"new buildsym_compunit" call that just seems useless / to do nothing.

In other words, no user-visible changes are expected from this patch.

Simon

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