Re: [PATCH v2] gdb/dwarf: disable per-BFD resource sharing for -readnow objfiles

[Tom Tromey <tom@tromey.com>]

Simon> I think the most sensible fix would be to not share a dwarf2_per_bfd
Simon> between two objfiles loaded with different methods.  That means that two
Simon> objfiles sharing the same BFD and loaded the same way would share a
Simon> dwarf2_per_bfd.  Two objfiles sharing the same BFD but loaded with
Simon> different methods would use two different dwarf2_per_bfd structures.

It seems to me that -readnow is a funny situation, because it is
intended to do something unusual.

For all other kinds of possible sharing, I think that deferring to
whatever was already done and recorded in the per-BFD object should work fine.
The idea here is just to bypass the reading step when possible.
So IMO it's fine to ignore the index cache if the psymtabs have already
been scanned -- reading from the cache won't give any benefits relative
to reusing the per-BFD object.

This seems like it would mainly be an issue for the ordering of checks
in dwarf2_initialize_objfile.  When I look there, it seems correct
already though -- the existing per-BFD is checked before trying to do
any scan or reading from the index cache.

Simon> 	* dwarf2/read.c (dwarf2_has_info): Don't share dwarf2_per_bfd
Simon> 	with objfiles using READNOW.

Thank you.  This looks good to me.  Thanks especially for the test case.

I think the ChangeLog entry should probably mention the PR though.

Tom