[PATCH] RISC-V/objdump: Do not re-seacrh for mapping symbols when didn't find any.

[Nelson Chu]

Hi,

On Fri, Sep 6, 2024 at 7:58 PM <dmitry.bushev@syntacore.com> wrote:

> From: Dmitry Bushev <dmitry.bushev@syntacore.com>
>
> In object files without any mapping symbols it's better to not
> search up to start of a section upon each instruction entry. Instead,
> cache symbol number from which search was started and if no symbol found,
> next time do not search past that symbol.
>
> Signed-off-by: Dmitry Bushev <dmitry.bushev@syntacore.com>
> ---
>  opcodes/riscv-dis.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/opcodes/riscv-dis.c b/opcodes/riscv-dis.c
> index 8ab138e45ce..c754e1d9460 100644
> --- a/opcodes/riscv-dis.c
> +++ b/opcodes/riscv-dis.c
> @@ -69,6 +69,7 @@ struct riscv_private_data
>  /* Used for mapping symbols.  */
>  static int last_map_symbol = -1;
>  static bfd_vma last_stop_offset = 0;
> +static int no_mapping_symbols_before = 0;
>

Considering compatibility,
static int last_map_symbol = -1;
+static int no_map_symbol_before = 0;
static bfd_vma last_stop_offset = 0;
...


>    /* If the last stop offset is different from the current one, then
>       don't use the last_map_symbol to search.  We usually reset the
> @@ -1172,8 +1176,9 @@ riscv_search_mapping_symbol (bfd_vma memaddr,
>    if (!found)
>      {
>        n = from_last_map_symbol ? last_map_symbol : info->symtab_pos;
> +      int start_n = n;
>

If we cannot find any map_symbol for this section, then
`from_last_map_symbol' will always be false, so `n' should always be
`info->symtab_pos', so ...


> -      for (; n >= 0; n--)
> +      for (; n >= no_mapping_symbols_before; n--)
>         {
>           bfd_vma addr = bfd_asymbol_value (info->symtab[n]);
>           /* We have searched all possible symbols in the range.  */
> @@ -1187,6 +1192,10 @@ riscv_search_mapping_symbol (bfd_vma memaddr,
>               break;
>             }
>         }
> +      /* Remember that we already scanned all symbols before start_n and
> +       * didn't find any. Next time, do not scan those symbols again. */
> +      if (!found)
> +       no_mapping_symbols_before = start_n;
>

moved this to ...


>      }
>
>    if (found)
>


if (found)
{
..
}
else
  no_map_symbol_before = info->symtab_pos;


Thanks
Nelson
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