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

14 files changed, 134 insertions, 29 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index ea44948..70c64c6 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,38 @@
+2016-07-15  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+	    Nick Clifton  <nickc@redhat.com>
+
+	* 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
+
 2016-07-15  Nick Clifton  <nickc@redhat.com>
 
 	* testsuite/ld-arc/arc.exp: Always run the sda-relocs test in
diff --git a/ld/NEWS b/ld/NEWS
index b988df0..2a0b4ac 100644
--- a/ld/NEWS
+++ b/ld/NEWS
@@ -1,5 +1,12 @@
 -*- text -*-
 
+Changes in 2.28:
+
+* Extended the --out-implib=<file> option, previously restricted to x86 PE
+  targets, to any ELF based target.  This allows the generation of an import
+  library for an ELF executable, which can then be used by another application
+  to link against the executable.
+
 Changes in 2.27:
 
 * Add a configure option --enable-relro to decide whether -z relro should
diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em
index 47fa549..dd4d35a 100644
--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -1027,6 +1027,20 @@ gld${EMULATION_NAME}_after_open (void)
   if (!is_elf_hash_table (htab))
     return;
 
+  if (command_line.out_implib_filename)
+    {
+      unlink_if_ordinary (command_line.out_implib_filename);
+      link_info.out_implib_bfd
+	= bfd_openw (command_line.out_implib_filename,
+		     bfd_get_target (link_info.output_bfd));
+
+      if (link_info.out_implib_bfd == NULL)
+	{
+	  einfo ("%F%s: Can't open for writing: %E\n",
+		 command_line.out_implib_filename);
+	}
+    }
+
   if (emit_note_gnu_build_id != NULL)
     {
       bfd *abfd;
diff --git a/ld/emultempl/pe.em b/ld/emultempl/pe.em
index c13fa4d..7b8fec7 100644
--- a/ld/emultempl/pe.em
+++ b/ld/emultempl/pe.em
@@ -138,7 +138,6 @@ static const char *emit_build_id;
 #ifdef DLL_SUPPORT
 static int pe_enable_stdcall_fixup = -1; /* 0=disable 1=enable.  */
 static char *pe_out_def_filename = NULL;
-static char *pe_implib_filename = NULL;
 static int pe_enable_auto_image_base = 0;
 static unsigned long pe_auto_image_base = 0x61500000;
 static char *pe_dll_search_prefix = NULL;
@@ -228,8 +227,7 @@ fragment <<EOF
 #define OPTION_STDCALL_ALIASES		(OPTION_KILL_ATS + 1)
 #define OPTION_ENABLE_STDCALL_FIXUP	(OPTION_STDCALL_ALIASES + 1)
 #define OPTION_DISABLE_STDCALL_FIXUP	(OPTION_ENABLE_STDCALL_FIXUP + 1)
-#define OPTION_IMPLIB_FILENAME		(OPTION_DISABLE_STDCALL_FIXUP + 1)
-#define OPTION_THUMB_ENTRY		(OPTION_IMPLIB_FILENAME + 1)
+#define OPTION_THUMB_ENTRY		(OPTION_DISABLE_STDCALL_FIXUP + 1)
 #define OPTION_WARN_DUPLICATE_EXPORTS	(OPTION_THUMB_ENTRY + 1)
 #define OPTION_IMP_COMPAT		(OPTION_WARN_DUPLICATE_EXPORTS + 1)
 #define OPTION_ENABLE_AUTO_IMAGE_BASE	(OPTION_IMP_COMPAT + 1)
@@ -323,7 +321,6 @@ gld${EMULATION_NAME}_add_options
     {"add-stdcall-alias", no_argument, NULL, OPTION_STDCALL_ALIASES},
     {"enable-stdcall-fixup", no_argument, NULL, OPTION_ENABLE_STDCALL_FIXUP},
     {"disable-stdcall-fixup", no_argument, NULL, OPTION_DISABLE_STDCALL_FIXUP},
-    {"out-implib", required_argument, NULL, OPTION_IMPLIB_FILENAME},
     {"warn-duplicate-exports", no_argument, NULL, OPTION_WARN_DUPLICATE_EXPORTS},
     /* getopt() allows abbreviations, so we do this to stop it from
        treating -c as an abbreviation for these --compat-implib.  */
@@ -461,7 +458,6 @@ gld_${EMULATION_NAME}_list_options (FILE *file)
   fprintf (file, _("                                     export, place into import library instead.\n"));
   fprintf (file, _("  --export-all-symbols               Automatically export all globals to DLL\n"));
   fprintf (file, _("  --kill-at                          Remove @nn from exported symbols\n"));
-  fprintf (file, _("  --out-implib <file>                Generate import library\n"));
   fprintf (file, _("  --output-def <file>                Generate a .DEF file for the built DLL\n"));
   fprintf (file, _("  --warn-duplicate-exports           Warn about duplicate exports\n"));
   fprintf (file, _("  --compat-implib                    Create backward compatible import libs;\n\
@@ -804,9 +800,6 @@ gld${EMULATION_NAME}_handle_option (int optc)
     case OPTION_DISABLE_STDCALL_FIXUP:
       pe_enable_stdcall_fixup = 0;
       break;
-    case OPTION_IMPLIB_FILENAME:
-      pe_implib_filename = xstrdup (optarg);
-      break;
     case OPTION_WARN_DUPLICATE_EXPORTS:
       pe_dll_warn_dup_exports = 1;
       break;
@@ -2070,8 +2063,9 @@ gld_${EMULATION_NAME}_finish (void)
     )
     {
       pe_dll_fill_sections (link_info.output_bfd, &link_info);
-      if (pe_implib_filename)
-	pe_dll_generate_implib (pe_def_file, pe_implib_filename, &link_info);
+      if (command_line.out_implib_filename)
+	pe_dll_generate_implib (pe_def_file, command_line.out_implib_filename,
+				&link_info);
     }
 #if defined(TARGET_IS_shpe)
   /* ARM doesn't need relocs.  */
diff --git a/ld/emultempl/pep.em b/ld/emultempl/pep.em
index ab7c473..60deeed 100644
--- a/ld/emultempl/pep.em
+++ b/ld/emultempl/pep.em
@@ -153,7 +153,6 @@ static const char *emit_build_id;
 #ifdef DLL_SUPPORT
 static int    pep_enable_stdcall_fixup = 1; /* 0=disable 1=enable (default).  */
 static char * pep_out_def_filename = NULL;
-static char * pep_implib_filename = NULL;
 static int    pep_enable_auto_image_base = 0;
 static char * pep_dll_search_prefix = NULL;
 #endif
@@ -217,7 +216,6 @@ enum options
   OPTION_STDCALL_ALIASES,
   OPTION_ENABLE_STDCALL_FIXUP,
   OPTION_DISABLE_STDCALL_FIXUP,
-  OPTION_IMPLIB_FILENAME,
   OPTION_WARN_DUPLICATE_EXPORTS,
   OPTION_IMP_COMPAT,
   OPTION_ENABLE_AUTO_IMAGE_BASE,
@@ -296,7 +294,6 @@ gld${EMULATION_NAME}_add_options
     {"add-stdcall-alias", no_argument, NULL, OPTION_STDCALL_ALIASES},
     {"enable-stdcall-fixup", no_argument, NULL, OPTION_ENABLE_STDCALL_FIXUP},
     {"disable-stdcall-fixup", no_argument, NULL, OPTION_DISABLE_STDCALL_FIXUP},
-    {"out-implib", required_argument, NULL, OPTION_IMPLIB_FILENAME},
     {"warn-duplicate-exports", no_argument, NULL, OPTION_WARN_DUPLICATE_EXPORTS},
     /* getopt() allows abbreviations, so we do this to stop it from
        treating -c as an abbreviation for these --compat-implib.  */
@@ -427,7 +424,6 @@ gld_${EMULATION_NAME}_list_options (FILE *file)
   fprintf (file, _("                                     export, place into import library instead.\n"));
   fprintf (file, _("  --export-all-symbols               Automatically export all globals to DLL\n"));
   fprintf (file, _("  --kill-at                          Remove @nn from exported symbols\n"));
-  fprintf (file, _("  --out-implib <file>                Generate import library\n"));
   fprintf (file, _("  --output-def <file>                Generate a .DEF file for the built DLL\n"));
   fprintf (file, _("  --warn-duplicate-exports           Warn about duplicate exports.\n"));
   fprintf (file, _("  --compat-implib                    Create backward compatible import libs;\n\
@@ -761,9 +757,6 @@ gld${EMULATION_NAME}_handle_option (int optc)
     case OPTION_DISABLE_STDCALL_FIXUP:
       pep_enable_stdcall_fixup = 0;
       break;
-    case OPTION_IMPLIB_FILENAME:
-      pep_implib_filename = xstrdup (optarg);
-      break;
     case OPTION_WARN_DUPLICATE_EXPORTS:
       pep_dll_warn_dup_exports = 1;
       break;
@@ -1851,8 +1844,9 @@ gld_${EMULATION_NAME}_finish (void)
 	  && pep_def_file->num_exports != 0))
     {
       pep_dll_fill_sections (link_info.output_bfd, &link_info);
-      if (pep_implib_filename)
-	pep_dll_generate_implib (pep_def_file, pep_implib_filename, &link_info);
+      if (command_line.out_implib_filename)
+	pep_dll_generate_implib (pep_def_file,
+				 command_line.out_implib_filename, &link_info);
     }
 
   if (pep_out_def_filename)
diff --git a/ld/ld.h b/ld/ld.h
index 85a48ad..410ee99 100644
--- a/ld/ld.h
+++ b/ld/ld.h
@@ -163,6 +163,9 @@ typedef struct
      input files.  */
   bfd_boolean accept_unknown_input_arch;
 
+  /* Name of the import library to generate.  */
+  char *out_implib_filename;
+
   /* If TRUE we'll just print the default output on stdout.  */
   bfd_boolean print_output_format;
 
diff --git a/ld/ld.texinfo b/ld/ld.texinfo
index bc16764..b2dff10 100644
--- a/ld/ld.texinfo
+++ b/ld/ld.texinfo
@@ -1721,6 +1721,16 @@ command @code{OUTPUT_FORMAT} can also specify the output format, but
 this option overrides it.  @xref{BFD}.
 @end ifclear
 
+@kindex --out-implib
+@item --out-implib @var{file}
+Create an import library in @var{file} corresponding to the executable
+the linker is generating (eg. a DLL or ELF program).  This import
+library (which should be called @code{*.dll.a} or @code{*.a} for DLLs)
+may be used to link clients against the generated executable; this
+behaviour makes it possible to skip a separate import library creation
+step (eg. @code{dlltool} for DLLs).  This option is only available for
+the i386 PE and ELF targetted ports of the linker.
+
 @kindex -pie
 @kindex --pic-executable
 @item -pie
@@ -2580,16 +2590,6 @@ automatically or implicitly exported symbols.
 [This option is specific to the i386 PE targeted port of the linker]
 
 @cindex DLLs, creating
-@kindex --out-implib
-@item --out-implib @var{file}
-The linker will create the file @var{file} which will contain an
-import lib corresponding to the DLL the linker is generating. This
-import lib (which should be called @code{*.dll.a} or @code{*.a}
-may be used to link clients against the generated DLL; this behaviour
-makes it possible to skip a separate @code{dlltool} import library
-creation step.
-[This option is specific to the i386 PE targeted port of the linker]
-
 @kindex --enable-auto-image-base
 @item --enable-auto-image-base
 @itemx --enable-auto-image-base=@var{value}
diff --git a/ld/ldexp.c b/ld/ldexp.c
index 649954f..68c4bc5 100644
--- a/ld/ldexp.c
+++ b/ld/ldexp.c
@@ -1183,6 +1183,7 @@ exp_fold_tree_1 (etree_type *tree)
 	      h->u.def.value = expld.result.value;
 	      h->u.def.section = expld.result.section;
 	      h->linker_def = ! tree->assign.type.lineno;
+	      h->ldscript_def = 1;
 	      if (tree->type.node_class == etree_provide)
 		tree->type.node_class = etree_provided;
 
diff --git a/ld/ldlex.h b/ld/ldlex.h
index cf943e4..52f7198 100644
--- a/ld/ldlex.h
+++ b/ld/ldlex.h
@@ -35,6 +35,7 @@ enum option_values
   OPTION_DYNAMIC_LINKER,
   OPTION_NO_DYNAMIC_LINKER,
   OPTION_SYSROOT,
+  OPTION_OUT_IMPLIB,
   OPTION_EB,
   OPTION_EL,
   OPTION_EMBEDDED_RELOCS,
diff --git a/ld/lexsup.c b/ld/lexsup.c
index 6d28e91..6e279ae 100644
--- a/ld/lexsup.c
+++ b/ld/lexsup.c
@@ -164,6 +164,8 @@ static const struct ld_option ld_options[] =
     'o', N_("FILE"), N_("Set output file name"), EXACTLY_TWO_DASHES },
   { {NULL, required_argument, NULL, '\0'},
     'O', NULL, N_("Optimize output file"), ONE_DASH },
+  { {"out-implib", required_argument, NULL, OPTION_OUT_IMPLIB},
+    '\0', N_("FILE"), N_("Generate import library"), TWO_DASHES },
 #ifdef ENABLE_PLUGINS
   { {"plugin", required_argument, NULL, OPTION_PLUGIN},
     '\0', N_("PLUGIN"), N_("Load named plugin"), ONE_DASH },
@@ -1004,6 +1006,9 @@ parse_args (unsigned argc, char **argv)
 	case OPTION_OFORMAT:
 	  lang_add_output_format (optarg, NULL, NULL, 0);
 	  break;
+	case OPTION_OUT_IMPLIB:
+	  command_line.out_implib_filename = xstrdup (optarg);
+	  break;
 	case OPTION_PRINT_SYSROOT:
 	  if (*ld_sysroot)
 	    puts (ld_sysroot);
diff --git a/ld/testsuite/ld-elf/elf.exp b/ld/testsuite/ld-elf/elf.exp
index 2dfd0e8..832f313 100644
--- a/ld/testsuite/ld-elf/elf.exp
+++ b/ld/testsuite/ld-elf/elf.exp
@@ -136,6 +136,22 @@ foreach t $test_list {
     run_dump_test [file rootname $t]
 }
 
+# Check that the --out-implib option work correctly.
+run_ld_link_tests {
+    {"Generate empty import library"
+     "--out-implib=tmpdir/implib.lib" ""
+     "--defsym NO_GLOBAL=1"
+     {implib.s}
+     {{ld empty-implib.out}}
+     "implib"}
+    {"Generate import library"
+     "-Tdata=0x1000 --out-implib=tmpdir/implib.lib" ""
+     ""
+     {implib.s}
+     {{readelf {-s tmpdir/implib.lib} implib.rd}}
+     "implib"}
+}
+
 if { [istarget *-*-linux*]
      || [istarget *-*-nacl*]
      || [istarget *-*-gnu*] } {
diff --git a/ld/testsuite/ld-elf/empty-implib.out b/ld/testsuite/ld-elf/empty-implib.out
new file mode 100644
index 0000000..b123064
--- /dev/null
+++ b/ld/testsuite/ld-elf/empty-implib.out
@@ -0,0 +1,2 @@
+.*: .*: no symbol found for import library
+.*: .*: failed to generate import library
diff --git a/ld/testsuite/ld-elf/implib.rd b/ld/testsuite/ld-elf/implib.rd
new file mode 100644
index 0000000..9f854a5
--- /dev/null
+++ b/ld/testsuite/ld-elf/implib.rd
@@ -0,0 +1,11 @@
+File: tmpdir/implib.lib
+
+Symbol table '.symtab' contains 3 entries:
+   Num:    Value +Size Type    Bind   Vis      Ndx Name
+     0: [0-9a-f]+     0 NOTYPE  LOCAL  DEFAULT  UND 
+     1: 0+100[0-3]     1 OBJECT  GLOBAL DEFAULT  ABS exported1
+     2: 0+100[0-3]     1 OBJECT  GLOBAL DEFAULT  ABS exported2
+
+File: tmpdir/implib
+
+#...
diff --git a/ld/testsuite/ld-elf/implib.s b/ld/testsuite/ld-elf/implib.s
new file mode 100644
index 0000000..a86a940
--- /dev/null
+++ b/ld/testsuite/ld-elf/implib.s
@@ -0,0 +1,22 @@
+.ifndef NO_GLOBAL
+	.bss
+	.comm	exported1,1
+
+	.data
+	.global	exported2
+	.type	exported2, %object
+	.size	exported2, 1
+exported2:
+	.byte	21
+.endif
+
+	.bss
+not_exported1:
+	.space	1
+	.size	not_exported1, 1
+
+	.data
+	.type	not_exported2, %object
+	.size	not_exported2, 1
+not_exported2:
+	.byte	42