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[PATCH] PR ld/21382: Handle symbol defined in IR and referenced in DSO


We need to make an IR symbol visible if it is defined in an IR object
and referenced in a dynamic object.  When --as-needed is used, since
linker removes the IR symbol reference of the dynamic object if the
dynamic object isn't needed in the first pass, the IR definition isn't
visible to the dynamic object even if the dynamic object becomes needed
in the second pass.  Add ir_def_dynamic_ref to bfd_link_hash_entry to
track IR symbol which is defined in an IR object and referenced in a
dynamic object.  ir_def_dynamic_ref is preserved when restoring the
symbol table for unneeded dynamic object.

OK for master?

H.J.
---
bfd/

	PR ld/21382
	* elflink.c (elf_link_add_object_symbols): Preserve
	re_def_dynamic_ref when restoring the symbol table for unneeded
	dynamic object.

include/

	PR ld/21382
	* bfdlink.h (bfd_link_hash_entry): Add ir_def_dynamic_ref.

ld/

	PR ld/21382
	* plugin.c (is_visible_from_outside): Symbol may be visible
	from outside if ir_def_dynamic_ref is set.
	(plugin_notice): Set ir_def_dynamic_ref if the symbol is
	defined in an IR object and referenced in a dynamic object.
	* testsuite/ld-plugin/lto.exp: Run PR ld/21382 tests.
	* testsuite/ld-plugin/pr21382a.c: New file.
	* testsuite/ld-plugin/pr21382b.c: Likewise.
---
 bfd/elflink.c                     |  6 ++++++
 include/bfdlink.h                 |  4 ++++
 ld/plugin.c                       | 23 +++++++++++++++++------
 ld/testsuite/ld-plugin/lto.exp    |  9 +++++++++
 ld/testsuite/ld-plugin/pr21382a.c | 17 +++++++++++++++++
 ld/testsuite/ld-plugin/pr21382b.c |  7 +++++++
 6 files changed, 60 insertions(+), 6 deletions(-)
 create mode 100644 ld/testsuite/ld-plugin/pr21382a.c
 create mode 100644 ld/testsuite/ld-plugin/pr21382b.c

diff --git a/bfd/elflink.c b/bfd/elflink.c
index dfcc51e..14c4a52 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -4887,6 +4887,7 @@ error_free_dyn:
 	  struct elf_link_hash_entry *h;
 	  bfd_size_type size;
 	  unsigned int alignment_power;
+	  unsigned int ir_def_dynamic_ref;
 
 	  for (p = htab->root.table.table[i]; p != NULL; p = p->next)
 	    {
@@ -4908,6 +4909,10 @@ error_free_dyn:
 		  size = 0;
 		  alignment_power = 0;
 		}
+	      /* Preserve re_def_dynamic_ref so that this symbol will
+		 be exported when the dynamic lib becomes needed in the
+		 second pass.  */
+	      ir_def_dynamic_ref = h->root.ir_def_dynamic_ref;
 	      memcpy (p, old_ent, htab->root.table.entsize);
 	      old_ent = (char *) old_ent + htab->root.table.entsize;
 	      h = (struct elf_link_hash_entry *) p;
@@ -4924,6 +4929,7 @@ error_free_dyn:
 		  if (alignment_power > h->root.u.c.p->alignment_power)
 		    h->root.u.c.p->alignment_power = alignment_power;
 		}
+	      h->root.ir_def_dynamic_ref = ir_def_dynamic_ref;
 	    }
 	}
 
diff --git a/include/bfdlink.h b/include/bfdlink.h
index 3835fcb..5dc1377 100644
--- a/include/bfdlink.h
+++ b/include/bfdlink.h
@@ -104,6 +104,10 @@ struct bfd_link_hash_entry
      IR object file.  */
   unsigned int non_ir_ref : 1;
 
+  /* Symbol is defined in an IR object and referenced in a dynamic
+     object.  */
+  unsigned int ir_def_dynamic_ref : 1;
+
   /* Symbol is a built-in define.  These will be overridden by PROVIDE
      in a linker script.  */
   unsigned int linker_def : 1;
diff --git a/ld/plugin.c b/ld/plugin.c
index 03e2e69..3a44eb2 100644
--- a/ld/plugin.c
+++ b/ld/plugin.c
@@ -629,7 +629,9 @@ is_visible_from_outside (struct ld_plugin_symbol *lsym,
 
   if (bfd_link_relocatable (&link_info))
     return TRUE;
-  if (link_info.export_dynamic || bfd_link_dll (&link_info))
+  if (blhe->ir_def_dynamic_ref
+      || link_info.export_dynamic
+      || bfd_link_dll (&link_info))
     {
       /* Check if symbol is hidden by version script.  */
       if (bfd_hide_sym_by_version (link_info.version_info,
@@ -1316,12 +1318,21 @@ plugin_notice (struct bfd_link_info *info,
       /* If this is a ref, set non_ir_ref.  */
       else if (bfd_is_und_section (section))
 	{
+	   if (h->type == bfd_link_hash_defweak
+	       || h->type == bfd_link_hash_defined)
+	     {
+	       /* Check if the symbol is defined in an IR object and
+		  referenced in a dynamic object.  */
+	       if ((abfd->flags & DYNAMIC) != 0
+		   && is_ir_dummy_bfd (h->u.def.section->owner))
+		 h->ir_def_dynamic_ref = TRUE;
+	     }
 	  /* Replace the undefined dummy bfd with the real one.  */
-	  if ((h->type == bfd_link_hash_undefined
-	       || h->type == bfd_link_hash_undefweak)
-	      && (h->u.undef.abfd == NULL
-		  || (h->u.undef.abfd->flags & BFD_PLUGIN) != 0))
-	    h->u.undef.abfd = abfd;
+	   else if ((h->type == bfd_link_hash_undefined
+		     || h->type == bfd_link_hash_undefweak)
+		    && (h->u.undef.abfd == NULL
+			|| (h->u.undef.abfd->flags & BFD_PLUGIN) != 0))
+	     h->u.undef.abfd = abfd;
 	  h->non_ir_ref = TRUE;
 	}
 
diff --git a/ld/testsuite/ld-plugin/lto.exp b/ld/testsuite/ld-plugin/lto.exp
index 80c084b..f0bc345 100644
--- a/ld/testsuite/ld-plugin/lto.exp
+++ b/ld/testsuite/ld-plugin/lto.exp
@@ -289,6 +289,12 @@ set lto_link_elf_tests [list \
   [list "PR ld/14918" \
    "-flto" "-flto" \
    {pr14918.c} {{"readelf" {-d --wide} "pr14918.d"}} "pr14918.exe" "c"] \
+  [list "Build pr21382a.o" \
+   "" "-O2 -flto" \
+   {pr21382a.c} {} "" "c"] \
+  [list "Build pr21382.so" \
+   "-shared" "-O2 -fpic" \
+   {pr21382b.c} {} "pr21382.so" "c"] \
 ]
 
 # Check final symbols in executables.
@@ -387,6 +393,9 @@ set lto_run_elf_shared_tests [list \
   [list "LTO 7" \
    "-O2 -flto -fuse-linker-plugin tmpdir/lto-7b.o tmpdir/lto-7c.o tmpdir/lto-7a.o -Wl,--no-as-needed tmpdir/liblto-7.so" "" \
    {dummy.c} "lto-7.exe" "lto-7.out" "" "c"] \
+  [list "Run pr21382" \
+   "-O2 -flto -fuse-linker-plugin -Wl,--as-needed tmpdir/pr21382a.o tmpdir/pr21382.so" "" \
+   {dummy.c} "pr21382.exe" "pass.out" "" "c"] \
 ]
 
 # LTO run-time tests for ELF
diff --git a/ld/testsuite/ld-plugin/pr21382a.c b/ld/testsuite/ld-plugin/pr21382a.c
new file mode 100644
index 0000000..09b9d75
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr21382a.c
@@ -0,0 +1,17 @@
+#include <stdio.h>
+
+extern void y (void);
+
+void
+x (void)
+{
+  printf ("PASS\n");
+}
+
+
+int
+main (void)
+{
+  y ();
+  return 0;
+}
diff --git a/ld/testsuite/ld-plugin/pr21382b.c b/ld/testsuite/ld-plugin/pr21382b.c
new file mode 100644
index 0000000..c5b74a9
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr21382b.c
@@ -0,0 +1,7 @@
+extern void x (void);
+
+void
+y (void)
+{
+  x ();
+}
-- 
2.9.3


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