Re: [PATCH] PR ld/19579/21306 Properly turn common symbol into definition

[Alan Modra <amodra at gmail dot com>]

On Thu, Apr 06, 2017 at 03:44:47PM -0700, H.J. Lu wrote:
> On Thu, Apr 6, 2017 at 3:40 PM, Alan Modra <amodra@gmail.com> wrote:
> > On Thu, Apr 06, 2017 at 10:45:32AM -0700, H.J. Lu wrote:
> >> Since common symbols that are turned into definitions don't have the
> >> DEF_REGULAR flag set, we need to check ELF_COMMON_DEF_P for common
> >> symbols.
> >>
> >> bfd/
> >>
> >>       PR ld/19579
> >>       PR ld/21306
> >>       * elf32-s390.c (elf_s390_finish_dynamic_symbol): Check
> >>       ELF_COMMON_DEF_P for common symbols.
> >>       * elf64-s390.c (elf_s390_finish_dynamic_symbol): Likewise.
> >>       * elf64-x86-64.c (elf_x86_64_relocate_section): Likewise.
> >>       * elflink.c (_bfd_elf_merge_symbol): Revert commits
> >>       202ac193bbbecc96a4978d1ac3d17148253f9b01 and
> >>       07492f668d2173da7a2bda3707ff0985e0f460b6.
> >>
> >> ld/
> >>
> >>       PR ld/19579
> >>       PR ld/21306
> >>       * testsuite/ld-elf/pr19579a.c (main): Updated.
> >
> > This is OK.  Thanks for looking at s390 too.  Which other targets do
> > you have cross-compilers installed or test natively in order to see
> > 19579 failures?  (I'm assuming that's why you made the s390 changes,
> 
> 19579 test needs a target compiler to compile.  I updated s390
> since the s390 code in question is in PR 19579.
> 
> > and would like to know the targets that might yet need attention.)
> >
> 
> It is hard to tell if other targets are affected since we don't need to
> check ELF_COMMON_DEF_P everywhere.

Right.  If I find myself bored with nothing else to do, I may audit
all the uses of def_regular in code that runs after lang_common, in
order to see whether we can delete ELF_COMMON_DEF_P and set
def_regular for commons instead.  It isn't hard to make your previous
patch work; You just need to define bfd_elfNN_bfd_define_common_symbol
conditionally in elfxx-target.h.  Search for "generic linker" there.

For now, I think adding ELF_COMMON_DEF_P as necessary is the best we
can do.

-- 
Alan Modra
Australia Development Lab, IBM