Re: [PATCH] RISC-V: fix linker message when relaxation deletes bytes

["Clément Chigot" <chigot@adacore.com>]

Gentle ping

Thanks,
Clément

On Thu, Oct 6, 2022 at 1:46 PM Clément Chigot <chigot@adacore.com> wrote:
>
> The section relaxation can delete some bytes resulting in the symbols'
> value being modified.
> As the linker messages retrieve a symbol information using the
> outsymbols field of abfd, it must be updated as well.
>
> bfd/ChangeLog:
>
>         * elfnn-riscv.c (riscv_relax_delete_bytes): Update
>         abfd->outsymbols.
>
> ld/ChangeLog:
>
>         * testsuite/ld-riscv-elf/ld-riscv-elf.exp: New test.
>         * testsuite/ld-riscv-elf/undefined-align.d: New test.
>         * testsuite/ld-riscv-elf/undefined-align.s: New test.
> ---
>  bfd/elfnn-riscv.c                           | 23 +++++++++++++++++++++
>  ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp  |  1 +
>  ld/testsuite/ld-riscv-elf/undefined-align.d |  5 +++++
>  ld/testsuite/ld-riscv-elf/undefined-align.s | 10 +++++++++
>  4 files changed, 39 insertions(+)
>  create mode 100644 ld/testsuite/ld-riscv-elf/undefined-align.d
>  create mode 100644 ld/testsuite/ld-riscv-elf/undefined-align.s
>
> diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
> index 3d2ddf4e651..7a6b66dcd8a 100644
> --- a/bfd/elfnn-riscv.c
> +++ b/bfd/elfnn-riscv.c
> @@ -4060,6 +4060,7 @@ riscv_relax_delete_bytes (bfd *abfd,
>    unsigned int sec_shndx = _bfd_elf_section_from_bfd_section (abfd, sec);
>    struct bfd_elf_section_data *data = elf_section_data (sec);
>    bfd_byte *contents = data->this_hdr.contents;
> +  asymbol **outsyms = bfd_get_outsymbols (abfd);
>
>    /* Actually delete the bytes.  */
>    sec->size -= count;
> @@ -4158,6 +4159,28 @@ riscv_relax_delete_bytes (bfd *abfd,
>         }
>      }
>
> +  /* As linker messages are getting symbols through outsymbols field of abfd,
> +     it must be adjusted too.  */
> +  if (outsyms == NULL)
> +    {
> +      if (!bfd_generic_link_read_symbols (abfd))
> +       link_info->callbacks->einfo (_("%F%P: %pB: could not read symbols: %E\n"), abfd);
> +      outsyms = bfd_get_outsymbols (abfd);
> +    }
> +
> +  for (i = 0; i < bfd_get_symcount (abfd); i++)
> +    {
> +      asymbol *sym = outsyms[i];
> +
> +      if (sym->section != sec)
> +       continue;
> +
> +      /* If the symbol is in the range of memory we just moved, we
> +        have to adjust its value.  */
> +      if (sym->value > addr && sym->value <= toaddr)
> +       sym->value -= count;
> +    }
> +
>    return true;
>  }
>
> diff --git a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
> index df89e0ee68b..86f1d05bc08 100644
> --- a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
> +++ b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
> @@ -176,6 +176,7 @@ if [istarget "riscv*-*-*"] {
>         [list "Weak reference 64" "-T weakref.ld -m[riscv_choose_lp64_emul]" "" \
>             "-march=rv64i -mabi=lp64" {weakref64.s} \
>             {{objdump -d weakref64.d}} "weakref64"]]
> +    run_dump_test "undefined-align"
>
>      # The following tests require shared library support.
>      if ![check_shared_lib_support] {
> diff --git a/ld/testsuite/ld-riscv-elf/undefined-align.d b/ld/testsuite/ld-riscv-elf/undefined-align.d
> new file mode 100644
> index 00000000000..c8cbb84ac7c
> --- /dev/null
> +++ b/ld/testsuite/ld-riscv-elf/undefined-align.d
> @@ -0,0 +1,5 @@
> +#name: undefined with alignment
> +#source: undefined-align.s
> +#as:
> +#ld: --relax
> +#error: \A[^\n]*\.o: in function `_start':\n\(\.text\+0x0\): undefined reference to `foo'\Z
> diff --git a/ld/testsuite/ld-riscv-elf/undefined-align.s b/ld/testsuite/ld-riscv-elf/undefined-align.s
> new file mode 100644
> index 00000000000..577557c663a
> --- /dev/null
> +++ b/ld/testsuite/ld-riscv-elf/undefined-align.s
> @@ -0,0 +1,10 @@
> +# Make sure that the linker messages take into account the modification
> +# of a symbol's value made during the section relaxation.
> +# Here, "_start" will have an offset made by ".align 4" which will be
> +# removed during the relaxation of R_RISCV_ALIGN.
> +       .text
> +       .align  4
> +       .globl  _start
> +       .type   _start, @function
> +_start:
> +       call    foo
> --
> 2.25.1
>