Re: [gold][patch] Reduce heap usage for string merge sections

[Ian Lance Taylor <iant at google dot com>]

Cary Coutant <ccoutant@google.com> writes:

>         * merge.cc (Output_merge_string::do_add_input_section): Count strings
>         to reserve space in merged_strings vector. Keep total input size
>         for stats.
>         (Output_merge_string::do_print_merge_stats): Print total input size.
>         * merge.h (Output_merge_string): Add input_size_ field.


> +  // Count the number of strings in the section and size the list.
> +  size_t count = 0;
> +  for (const Char_type* pl = p; pl < pend; ++pl)
> +    {
> +      if (*pl == 0)
> +	++count;
> +    }

In the case where Char_type is char, I have a feeling this loop would be
a tiny bit faster if written as

  const Char_type* pl = p;
  while (pl < pend)
    {
      pl += strlen(pl) + 1;
      if (pl > pend)
        warning(...);
      ++count;
    }

This is simply because the compiler will optimize strlen for the
specific compilation target.  See
Stringpool_template<char>::string_length for a similar optimization in
the Stringpool code.


Also, since you have the exact count, it would be a tiny bit better to
allocate the vector at that size rather than allocating a default vector
and then using reserve.  You could this by adding a parameter to the
Merged_strings_list constructor which is passed to merged_strings.


This is OK with or without those changes.

Thanks.

Ian