PING [PATCH] gold: Support SHF_GNU_RETAIN

[Cary Coutant]

+      elfcpp::Elf_Xword ignored_flags;
+      elfcpp::ELFOSABI osabi = object->osabi();
+      if (osabi == elfcpp::ELFOSABI_GNU
+         || osabi == elfcpp::ELFOSABI_FREEBSD)
+       ignored_flags = elfcpp::SHF_GNU_RETAIN;
+      else
+       ignored_flags = 0;

Rather than scatter OS ABI logic all over the place, I'd rather create
a class Osabi that can abstract this logic into one place, and use it
like this:

+      // Get the section flags and mask out any flags that do not
+      // take part in section matching.
+      elfcpp::Elf_Xword sh_flags
+         = (this->get_output_section_flags(shdr.get_sh_flags())
+            & ~object->osabi().ignored_sh_flags());

I've promoted this to the top of the if...else chain so that it gets
done only once in Layout::layout().

In Sized_relobj_file::do_layout(), we can do this:

       if (is_pass_one && parameters->options().gc_sections())
        {
+         elfcpp::ELFOSABI osabi = this->osabi();
          if (this->is_section_name_included(name)
              || layout->keep_input_section (this, name)
              || sh_type == elfcpp::SHT_INIT_ARRAY
-             || sh_type == elfcpp::SHT_FINI_ARRAY)
+             || sh_type == elfcpp::SHT_FINI_ARRAY
+             || ((osabi == elfcpp::ELFOSABI_GNU
+                  || osabi == elfcpp::ELFOSABI_FREEBSD)
+                 && shdr.get_sh_flags() & elfcpp::SHF_GNU_RETAIN) != 0)
            {
              symtab->gc()->worklist().push_back(Section_id(this, i));
            }

The parentheses are messed up here. Using the new Osabi class, I've
simplified this to:

+             || this->osabi().has_shf_retain(shdr.get_sh_flags()))

Updated patch is attached. Will commit shortly.

Thanks for working on this!

-cary
-------------- next part --------------
A non-text attachment was scrubbed...
Name: retain.patch
Type: application/octet-stream
Size: 12697 bytes
Desc: not available
URL: <https://sourceware.org/pipermail/binutils/attachments/20201214/567fef89/attachment-0001.obj>