[PATCH] RISC-V: PR27584, surpress local and empty name symbols for nm.

[Nelson Chu]

Thanks, Palmer :)  Committed.

Nelson

On Wed, Apr 14, 2021 at 11:38 AM Palmer Dabbelt <palmer@dabbelt.com> wrote:
>
> On Tue, 13 Apr 2021 20:31:20 PDT (-0700), nelson.chu@sifive.com wrote:
> > The local ".L0" symbol are usually generated to mark where the
> > auipc instruction is, and clang also uses ".LBB" to do the same
> > thing.  Besides, clang also uses the empty name symbols for label
> > differences.  Arm surpress their mapping symbols by regarding them
> > as special symbols, and MIPS surpress all local symbols.  Therefore,
> > maybe RISC-V also need to surpress the local and empty name symbols
> > for nm and related tools.  User can use "--special-syms" to show
> > these surpressed symbols if they want.
> >
> > bfd/
> >     * elfnn-riscv.c (riscv_elf_is_target_special_symbol): Added to
> >     omit local and empty symbols since they usually generated to
> >     mark the auipc instructions.
> > ---
> >  bfd/elfnn-riscv.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> >
> > diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
> > index 5e29278..a944b33 100644
> > --- a/bfd/elfnn-riscv.c
> > +++ b/bfd/elfnn-riscv.c
> > @@ -5094,6 +5094,16 @@ riscv_elf_obj_attrs_arg_type (int tag)
> >    return (tag & 1) != 0 ? ATTR_TYPE_FLAG_STR_VAL : ATTR_TYPE_FLAG_INT_VAL;
> >  }
> >
> > +/* PR27584, Omit local and empty symbols since they usually generated
> > +   for pcrel relocations.  */
> > +
> > +static bool
> > +riscv_elf_is_target_special_symbol (bfd *abfd, asymbol *sym)
> > +{
> > +  return (!strcmp (sym->name, "")
> > +       || _bfd_elf_is_local_label_name (abfd, sym->name));
> > +}
> > +
> >  #define TARGET_LITTLE_SYM                    riscv_elfNN_vec
> >  #define TARGET_LITTLE_NAME                   "elfNN-littleriscv"
> >  #define TARGET_BIG_SYM                               riscv_elfNN_be_vec
> > @@ -5106,6 +5116,7 @@ riscv_elf_obj_attrs_arg_type (int tag)
> >  #define bfd_elfNN_bfd_reloc_type_lookup              riscv_reloc_type_lookup
> >  #define bfd_elfNN_bfd_merge_private_bfd_data \
> >    _bfd_riscv_elf_merge_private_bfd_data
> > +#define bfd_elfNN_bfd_is_target_special_symbol       riscv_elf_is_target_special_symbol
> >
> >  #define elf_backend_copy_indirect_symbol     riscv_elf_copy_indirect_symbol
> >  #define elf_backend_create_dynamic_sections  riscv_elf_create_dynamic_sections
>
> LGTM.  IIRC we already suppress these elsewhere, so this is either a
> regression or we forgot to look at nm.
>
> Thanks!