Make __start/__stop symbols dynamic and add testcase

bfd/
	* elflink.c (bfd_elf_define_start_stop): Make __start and __stop
	symbols dynamic.
ld/
	* testsuite/ld-elf/pr21964-3a.c: New file.
	* testsuite/ld-elf/pr21964-3c.c: New file.
	* testsuite/ld-elf/shared.exp: Run new __start/__stop testcase.

bfd/ChangeLog

@@ -1,3 +1,8 @@
+2018-01-30  Alan Modra  <amodra@gmail.com>
+
+	* elflink.c (bfd_elf_define_start_stop): Make __start and __stop
+	symbols dynamic.
+
 2018-01-29  Alan Modra  <amodra@gmail.com>
 
 	PR 22741

bfd/elflink.c

@@ -14354,8 +14354,13 @@ bfd_elf_define_start_stop (struct bfd_link_info *info,
 	  bed = get_elf_backend_data (info->output_bfd);
 	  (*bed->elf_backend_hide_symbol) (info, h, TRUE);
 	}
-      else if (ELF_ST_VISIBILITY (h->other) == STV_DEFAULT)
-	h->other = (h->other & ~ELF_ST_VISIBILITY (-1)) | STV_PROTECTED;
+      else
+	{
+	  if (ELF_ST_VISIBILITY (h->other) == STV_DEFAULT)
+	    h->other = (h->other & ~ELF_ST_VISIBILITY (-1)) | STV_PROTECTED;
+	  if (h->ref_dynamic || h->def_dynamic)
+	    bfd_elf_link_record_dynamic_symbol (info, h);
+	}
       return &h->root;
     }
   return NULL;

ld/ChangeLog

@@ -1,3 +1,9 @@
+2018-01-29  Alan Modra  <amodra@gmail.com>
+
+	* testsuite/ld-elf/pr21964-3a.c: New file.
+	* testsuite/ld-elf/pr21964-3c.c: New file.
+	* testsuite/ld-elf/shared.exp: Run new __start/__stop testcase.
+
 2018-01-29  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* testsuite/ld-elf/shared.exp (AFLAGS_PIC): Define on SPARC.

ld/testsuite/ld-elf/pr21964-3a.c

@@ -0,0 +1,11 @@
+extern int __start___verbose[];
+extern int __stop___verbose[];
+int
+foo3 (void)
+{
+  if (__start___verbose == __stop___verbose
+      || __start___verbose[0] != 6)
+    return -1;
+  else
+    return 0;
+}

ld/testsuite/ld-elf/pr21964-3c.c

@@ -0,0 +1,17 @@
+#include <stdio.h>
+
+extern int foo1 (void);
+extern int foo2 (void);
+extern int foo3 (void);
+
+static int my_var __attribute__((used, section("__verbose"))) = 6;
+
+int
+main ()
+{
+  if (foo1 () == 0
+      && foo2 () == 0
+      && foo3 () == 0)
+    printf ("PASS\n");
+  return 0;
+}

ld/testsuite/ld-elf/shared.exp

@@ -569,6 +569,9 @@ set build_tests {
   {"Build pr21964-2b.so"
    "-shared" "-fPIC"
    {pr21964-2b.c} {} "pr21964-2b.so"}
+  {"Build pr21964-3a.so"
+   "-shared" "-fPIC"
+   {pr21964-3a.c} {} "pr21964-3a.so"}
   {"Dump pr21978.so"
    "-shared" "-fPIC -g -O2"
    {pr21978a.c pr21978b.c} {{objdump {-Sl} pr21978.od}} "pr21978.so"}
@@ -705,6 +708,9 @@ set run_tests [list \
     [list "Run pr21964-1" \
      "-Wl,--no-as-needed,-rpath,tmpdir tmpdir/pr21964-1a.so tmpdir/pr21964-1b.so" "" \
      {pr21964-1c.c} "pr21964-1" "pass.out" ] \
+    [list "Run pr21964-3" \
+     "-Wl,--no-as-needed,-rpath,tmpdir tmpdir/pr21964-1a.so tmpdir/pr21964-1b.so tmpdir/pr21964-3a.so" "" \
+     {pr21964-3c.c} "pr21964-3" "pass.out" ] \
 ]
 
 # NetBSD ELF systems do not currently support the .*_array sections.