ld: Extract _bfd_elf_link_iterate_on_relocs

DT_RELR encodes consecutive R_*_RELATIVE relocations in GOT (the global
offset table) and data sections in a compact format:

https://groups.google.com/g/generic-abi/c/bX460iggiKg

On some targets, R_*_RELATIVE relocations are counted and the GOT offsets
are allocated when setting the dynamic section sizes after seeing all
relocations.  R_*_RELATIVE relocations are generated while relocating
sections after section layout has been finalized.

To prepare for DT_RELR implementation on these targets, extract
_bfd_elf_link_iterate_on_relocs from _bfd_elf_link_check_relocs so
that a backend can scan relocations in elf_backend_always_size_sections

For x86 targets, the old check_relocs is renamed to scan_relocs and a
new check_relocs is added to chek input sections and create dynamic
relocation sections so that they will be mapped to output sections.
scan_relocs is now called from elf_backend_always_size_sections.

Since relocations are scanned after __start, __stop, .startof. and
.sizeof. symbols have been finalized on x86, __[start|stop]_SECNAME for
--gc-sections -z start-stop-gc are now zero when all SECNAME sections
been garbage collected.  This is no need for elf_x86_start_stop_gc_p.

bfd/

	* elf-bfd.h (_bfd_elf_link_iterate_on_relocs): New.
	* elf32-i386.c (elf_i386_convert_load_reloc): Don't call
	elf_x86_start_stop_gc_p.
	(elf_i386_check_relocs): Renamed to ...
	(elf_i386_scan_relocs): This.  Don't call
	_bfd_elf_make_dynamic_reloc_section.
	(elf_i386_always_size_sections): New.
	(elf_backend_check_relocs): Removed.
	(elf_backend_always_size_sections): New.
	* elf64-x86-64.c (elf_x86_64_convert_load_reloc): Don't call
	elf_x86_start_stop_gc_p.
	(elf_x86_64_check_relocs): Renamed to ...
	(elf_x86_64_scan_relocs): This.  Don't call
	_bfd_elf_make_dynamic_reloc_section.
	(elf_x86_64_always_size_sections): New.
	(elf_backend_check_relocs): Removed.
	(elf_backend_always_size_sections): New.
	* elflink.c (elf_link_check_or_scan_relocs):
	New.  Extracted from _bfd_elf_link_check_relocs.
	(_bfd_elf_link_check_relocs): Call elf_link_check_or_scan_relocs.
	* elfxx-x86.c (_bfd_x86_elf_check_relocs): New.
	* elfxx-x86.h (X86_64_NEED_DYNAMIC_RELOC_TYPE_P): New.
	(I386_NEED_DYNAMIC_RELOC_TYPE_P): Likewise.
	(X86_NEED_DYNAMIC_RELOC_TYPE_P): Likewise.
	(_bfd_x86_elf_check_relocs): Likewise.
	(elf_backend_check_relocs): Likewise.
	(elf_backend_always_size_sections): Removed.
	(elf_x86_start_stop_gc_p): Likewise.

ld/

	* testsuite/ld-i386/pr27491-1a.d: Updated.
	* testsuite/ld-x86-64/pr27491-1a.d: Likewise.

1 files changed, 85 insertions, 0 deletions

diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
index ca4b90e..25f7717 100644
--- a/bfd/elfxx-x86.c
+++ b/bfd/elfxx-x86.c
@@ -892,6 +892,91 @@ _bfd_x86_elf_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
   return _bfd_elf_link_check_relocs (abfd, info);
 }
 
+/* Look through the relocs for a section before allocation to make the
+   dynamic reloc section.  */
+
+bool
+_bfd_x86_elf_check_relocs (bfd *abfd,
+			   struct bfd_link_info *info,
+			   asection *sec,
+			   const Elf_Internal_Rela *relocs)
+{
+  struct elf_x86_link_hash_table *htab;
+  Elf_Internal_Shdr *symtab_hdr;
+  struct elf_link_hash_entry **sym_hashes;
+  const Elf_Internal_Rela *rel;
+  const Elf_Internal_Rela *rel_end;
+  asection *sreloc;
+  const struct elf_backend_data *bed;
+  bool is_x86_64;
+
+  if (bfd_link_relocatable (info))
+    return true;
+
+  bed = get_elf_backend_data (abfd);
+  htab = elf_x86_hash_table (info, bed->target_id);
+  if (htab == NULL)
+    {
+      sec->check_relocs_failed = 1;
+      return false;
+    }
+
+  is_x86_64 = bed->target_id == X86_64_ELF_DATA;
+
+  symtab_hdr = &elf_symtab_hdr (abfd);
+  sym_hashes = elf_sym_hashes (abfd);
+
+  rel_end = relocs + sec->reloc_count;
+  for (rel = relocs; rel < rel_end; rel++)
+    {
+      unsigned int r_type;
+      unsigned int r_symndx;
+      struct elf_link_hash_entry *h;
+
+      r_symndx = htab->r_sym (rel->r_info);
+      r_type = ELF32_R_TYPE (rel->r_info);
+
+      if (r_symndx >= NUM_SHDR_ENTRIES (symtab_hdr))
+	{
+	  /* xgettext:c-format */
+	  _bfd_error_handler (_("%pB: bad symbol index: %d"),
+			      abfd, r_symndx);
+	  goto error_return;
+	}
+
+      if (r_symndx < symtab_hdr->sh_info)
+	h = NULL;
+      else
+	{
+	  h = sym_hashes[r_symndx - symtab_hdr->sh_info];
+	  while (h->root.type == bfd_link_hash_indirect
+		 || h->root.type == bfd_link_hash_warning)
+	    h = (struct elf_link_hash_entry *) h->root.u.i.link;
+	}
+
+      if (X86_NEED_DYNAMIC_RELOC_TYPE_P (is_x86_64, r_type)
+	  && NEED_DYNAMIC_RELOCATION_P (is_x86_64, info, true, h, sec,
+					r_type, htab->pointer_r_type))
+	{
+	  /* We may copy these reloc types into the output file.
+	     Create a reloc section in dynobj and make room for
+	     this reloc.  */
+	  sreloc = _bfd_elf_make_dynamic_reloc_section
+	    (sec, htab->elf.dynobj, ABI_64_P (abfd) ? 3 : 2,
+	     abfd, sec->use_rela_p);
+
+	  if (sreloc != NULL)
+	    return true;
+
+  error_return:
+	  sec->check_relocs_failed = 1;
+	  return false;
+	}
+    }
+
+  return true;
+}
+
 bool
 _bfd_elf_x86_valid_reloc_p (asection *input_section,
 			    struct bfd_link_info *info,