Re: PING^2: [PATCH v3] elf: Always honor the first definition in shared object and archive

[Alan Modra <amodra@gmail.com>]

On Fri, Apr 05, 2024 at 05:00:28AM -0700, H.J. Lu wrote:
> On Fri, Apr 5, 2024 at 3:15 AM Nick Clifton <nickc@redhat.com> wrote:
> >
> > Hi H.J.
> >
> > >>> GCC doesn't put builtin function symbol references, which are defined in
> > >>> the shared C library, in the IR symbol table.  When linker rescans shared
> > >>> objects and archives for newly added symbol references generated from the
> > >>> IR inputs, it skips definitions of the builtin functions in shared
> > >>> objects and archives.
> > >>>
> > >>> Add first_hash to elf_link_hash_table to track unreferenced definitions
> > >>> defined first in shared objects and archives.  Always use them to resolve
> > >>> any references.
> >
> > Approved - please apply.
> >
> > Cheers
> >    Nick
> >
> 
> I am checking in the v2 patch:
> 
> https://sourceware.org/pipermail/binutils/2024-April/133395.html

I had some further requests to make.
1) If you are going to use a bfd_hash_table based first_hash, please
don't use bfd_link_hash_table.  Instead extend bfd_hash_entry with a
single abfd field.  You'll need to write a newfunc, but that's about
all that is required.  There are multiple examples of this in the
source, eg. bfd/stabs.c stab_link_includes_entry.

2) You are accessing freed memory in _bfd_elf_link_hash_table_free.
Free first_hash before freeing the main hash table.  That needs fixing
immediately.

3) Please ensure tests have different names.  This
  [list {pr31482a} \
   {-Wl,--no-as-needed,-R,tmpdir} {} \
   {pr31482a.c} {pr31482a.exe} {pass.out} {-flto} {c} {} \
   {tmpdir/pr31482b.a tmpdir/pr31482c.so}] \
  [list {pr31482b} \
   {-Wl,--no-as-needed,-R,tmpdir} {} \
   {pr31482a.c} {pr31482b.exe} {pass1.out} {-flto} {c} {} \
   {tmpdir/pr31482c.so tmpdir/pr31482b.a}] \
  [list {pr31489a} \
   {-Wl,--as-needed,-R,tmpdir} {} \
   {pr31482a.c} {pr31489a.exe} {pass.out} {-flto} {c} {} \
   {tmpdir/pr31482b.a tmpdir/pr31482c.so}] \
  [list {pr31489b} \
   {-Wl,--as-needed,-R,tmpdir} {} \
   {pr31482a.c} {pr31489b.exe} {pass1.out} {-flto} {c} {} \
   {tmpdir/pr31482c.so tmpdir/pr31482b.a}] \
has two tests called pr31489a and two called pr31489b.
"FAIL: pr31489a" as the output of make check isn't as helpful as it
could be.  Better would be to add --no-as-needed and --as-needed to
the test names.

-- 
Alan Modra
Australia Development Lab, IBM