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, 19 insertions, 4 deletions

diff --git a/bfd/elflink.c b/bfd/elflink.c
index 08c161713cc..059461b5725 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -4008,10 +4008,13 @@ _bfd_elf_notice_as_needed (bfd *ibfd,
   return (*info->callbacks->notice) (info, NULL, NULL, ibfd, NULL, act, 0);
 }
 
-/* Check relocations an ELF object file.  */
+/* Call ACTION on each relocation in an ELF object file.  */
 
 bool
-_bfd_elf_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
+_bfd_elf_link_iterate_on_relocs
+  (bfd *abfd, struct bfd_link_info *info,
+   bool (*action) (bfd *, struct bfd_link_info *, asection *,
+		   const Elf_Internal_Rela *))
 {
   const struct elf_backend_data *bed = get_elf_backend_data (abfd);
   struct elf_link_hash_table *htab = elf_hash_table (info);
@@ -4035,7 +4038,6 @@ _bfd_elf_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
      different format.  It probably can't be done.  */
   if ((abfd->flags & DYNAMIC) == 0
       && is_elf_hash_table (&htab->root)
-      && bed->check_relocs != NULL
       && elf_object_id (abfd) == elf_hash_table_id (htab)
       && (*bed->relocs_compatible) (abfd->xvec, info->output_bfd->xvec))
     {
@@ -4070,7 +4072,7 @@ _bfd_elf_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
 	  if (internal_relocs == NULL)
 	    return false;
 
-	  ok = (*bed->check_relocs) (abfd, info, o, internal_relocs);
+	  ok = action (abfd, info, o, internal_relocs);
 
 	  if (elf_section_data (o)->relocs != internal_relocs)
 	    free (internal_relocs);
@@ -4083,6 +4085,19 @@ _bfd_elf_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
   return true;
 }
 
+/* Check relocations in an ELF object file.  This is called after
+   all input files have been opened.  */
+
+bool
+_bfd_elf_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
+{
+  const struct elf_backend_data *bed = get_elf_backend_data (abfd);
+  if (bed->check_relocs != NULL)
+    return _bfd_elf_link_iterate_on_relocs (abfd, info,
+					    bed->check_relocs);
+  return true;
+}
+
 /* Add symbols from an ELF object file to the linker hash table.  */
 
 static bool