Add support for creating ELF import libraries

2016-07-15  Thomas Preud'homme  <thomas.preudhomme@arm.com>

bfd/
	* elf-bfd.h (elf_backend_filter_implib_symbols): Declare backend hook.
	(_bfd_elf_filter_global_symbols): Declare.
	* elf.c (_bfd_elf_filter_global_symbols): New function.
	* elflink.c (elf_filter_global_symbols): Likewise.
	(elf_output_implib): Likewise.
	(bfd_elf_final_link): Call above function, failing if it does.
	* elfxx-target.h (elf_backend_filter_implib_symbols): Define macro and
	default it to NULL.
	(elf_backend_copy_indirect_symbol): Fix spacing.
	(elf_backend_hide_symbol): Likewise.
	(elfNN_bed): Initialize elf_backend_filter_implib_symbols backend hook.

include/
	* bfdlink.h (struct bfd_link_info): Declare new ldscript_def and
	out_implib_bfd fields.

2016-07-15  Thomas Preud'homme  <thomas.preudhomme@arm.com>
	    Nick Clifton  <nickc@redhat.com>

ld/
	* emultempl/elf32.em (gld${EMULATION_NAME}_after_open): Open import
	library file for writing and initialize implib_bfd field of link_info
	structure.
	* emultempl/pe.em (pe_implib_filename): Remove variable declaration.
	(OPTION_IMPLIB_FILENAME): Remove macro definition.
	(gld${EMULATION_NAME}_add_options): Remove --out-implib option.
	(gld_${EMULATION_NAME}_list_options): Likewise.
	(gld${EMULATION_NAME}_handle_option): Likewise.
	(gld_${EMULATION_NAME}_finish): Use command_line.out_implib_filename
	instead of pe_implib_filename.
	* emultempl/pep.em (pep_implib_filename): Remove variable declaration.
	(OPTION_IMPLIB_FILENAME): Remove enumerator.
	(gld${EMULATION_NAME}_add_options): Remove --out-implib option.
	(gld_${EMULATION_NAME}_list_options): Likewise.
	(gld${EMULATION_NAME}_handle_option): Likewise.
	(gld_${EMULATION_NAME}_finish): Use command_line.out_implib_filename
	instead of pep_implib_filename.
	* ld.h (args_type): Declare new out_implib_filename field.
	* ld.texinfo (--out-implib): Move documentation to arch-independent
	part and rephrase to apply to ELF targets.
	* ldexp.c (exp_fold_tree_1): Set ldscript_def field to 1 for symbols
	defined in linker scripts.
	* ldlex.h (enum option_values): Declare new OPTION_OUT_IMPLIB
	enumerator.
	* lexsup.c (ld_options): Add entry for new --out-implib switch.
	(parse_args): Handle OPTION_OUT_IMPLIB case.
	* testsuite/ld-elf/elf.exp (Generate empty import library): New test.
	(Generate import library): Likewise.
	* testsuite/ld-elf/implib.s: Likewise.
	* testsuite/ld-elf/implib.rd: New file.
	* testsuite/ld-elf/empty-implib.out: Likewise

1 files changed, 37 insertions, 0 deletions

diff --git a/bfd/elf.c b/bfd/elf.c
index cb4de50..ebcf40a 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -3870,6 +3870,43 @@ sym_is_global (bfd *abfd, asymbol *sym)
 	  || bfd_is_com_section (bfd_get_section (sym)));
 }
 
+/* Filter global symbols of ABFD to include in the import library.  All
+   SYMCOUNT symbols of ABFD can be examined from their pointers in
+   SYMS.  Pointers of symbols to keep should be stored contiguously at
+   the beginning of that array.
+
+   Returns the number of symbols to keep.  */
+
+unsigned int
+_bfd_elf_filter_global_symbols (bfd *abfd, struct bfd_link_info *info,
+				asymbol **syms, long symcount)
+{
+  long src_count, dst_count = 0;
+
+  for (src_count = 0; src_count < symcount; src_count++)
+    {
+      asymbol *sym = syms[src_count];
+      char *name = (char *) bfd_asymbol_name (sym);
+      struct bfd_link_hash_entry *h;
+
+      if (!sym_is_global (abfd, sym))
+	continue;
+
+      h = bfd_link_hash_lookup (info->hash, name, FALSE, FALSE, FALSE);
+      if (h->type != bfd_link_hash_defined && h->type != bfd_link_hash_defweak)
+	continue;
+
+      if (h->linker_def || h->ldscript_def)
+	continue;
+
+      syms[dst_count++] = sym;
+    }
+
+  syms[dst_count] = NULL;
+
+  return dst_count;
+}
+
 /* Don't output section symbols for sections that are not going to be
    output, that are duplicates or there is no BFD section.  */