Don't issue a warning for references in LTO IR to warning symbols

bfd/
	PR ld/16746
	* linker.c (_bfd_generic_link_add_one_symbol): Don't issue a
	warning for references in LTO IR to warning symbols.

ld/testsuite/
	PR ld/16746
	* ld-plugin/lto.exp: Add 4 tests for PR ld/16746.
	* ld-plugin/pr16746a.c: New file.
	* ld-plugin/pr16746b.c: Likewise.
	* ld-plugin/pr16746c.c: Likewise.
	* ld-plugin/pr16746d.c: Likewise.

8 files changed, 73 insertions, 8 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index ad651a6..edbcffa 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,10 @@
+2014-08-07  H.J. Lu  <hongjiu.lu@intel.com>
+	    Alan Modra  <amodra@gmail.com>
+
+	PR ld/16746
+	* linker.c (_bfd_generic_link_add_one_symbol): Don't issue a
+	warning for references in LTO IR to warning symbols.
+
 2014-08-07  Alan Modra  <amodra@gmail.com>
 
 	* linker.c (WARN, CWARN): Collapse these states to WARN.
diff --git a/bfd/linker.c b/bfd/linker.c
index 93c5465..d4b053c 100644
--- a/bfd/linker.c
+++ b/bfd/linker.c
@@ -1776,8 +1776,10 @@ _bfd_generic_link_add_one_symbol (struct bfd_link_info *info,
 	  break;
 
 	case WARNC:
-	  /* Issue a warning and cycle.  */
-	  if (h->u.i.warning != NULL)
+	  /* Issue a warning and cycle, except when the reference is
+	     in LTO IR.  */
+	  if (h->u.i.warning != NULL
+	      && (abfd->flags & BFD_PLUGIN) == 0)
 	    {
 	      if (! (*info->callbacks->warning) (info, h->u.i.warning,
 						 h->root.string, abfd,
@@ -1802,12 +1804,9 @@ _bfd_generic_link_add_one_symbol (struct bfd_link_info *info,
 	  break;
 
 	case WARN:
-	  /* Warn if this symbol has been referenced already,
-	     otherwise add a warning.  A symbol has been referenced if
-	     the u.undef.next field is not NULL, or it is the tail of the
-	     undefined symbol list.  The REF case above helps to
-	     ensure this.  */
-	  if (h->u.undef.next != NULL || info->hash->undefs_tail == h)
+	  /* Warn if this symbol has been referenced already from non-IR,
+	     otherwise add a warning.  */
+	  if (h->non_ir_ref)
 	    {
 	      if (! (*info->callbacks->warning) (info, string, h->root.string,
 						 hash_entry_bfd (h), NULL, 0))
diff --git a/ld/testsuite/ChangeLog b/ld/testsuite/ChangeLog
index da8f2f5..bcddeac 100644
--- a/ld/testsuite/ChangeLog
+++ b/ld/testsuite/ChangeLog
@@ -1,3 +1,12 @@
+2014-08-07  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/16746
+	* ld-plugin/lto.exp: Add 4 tests for PR ld/16746.
+	* ld-plugin/pr16746a.c: New file.
+	* ld-plugin/pr16746b.c: Likewise.
+	* ld-plugin/pr16746c.c: Likewise.
+	* ld-plugin/pr16746d.c: Likewise.
+
 2014-08-06  Alan Modra  <amodra@gmail.com>
 
 	* lib/ld-lib.exp (check_lto_fat_available): New.
diff --git a/ld/testsuite/ld-plugin/lto.exp b/ld/testsuite/ld-plugin/lto.exp
index 432c753..7ff5bfb 100644
--- a/ld/testsuite/ld-plugin/lto.exp
+++ b/ld/testsuite/ld-plugin/lto.exp
@@ -232,6 +232,18 @@ set lto_link_elf_tests [list \
   [list "Build libpr15146d.a" \
    "$plug_opt" "-flto -O2" \
    {pr15146d.c} {} "lib15146d.a"] \
+  [list "Build libpr16746a.a" \
+   "" "" \
+   {pr16746a.c pr16746b.c} {} "lib15146a.a"] \
+  [list "Build libpr16746b.a" \
+   "$plug_opt" "-O2 -flto" \
+   {pr16746c.c pr16746d.c} {} "lib15146b.a"] \
+  [list "PR ld/16746 (1)" \
+   "-O2 -flto -fuse-linker-plugin tmpdir/pr16746a.o tmpdir/pr16746c.o" "-O2 -flto" \
+   {dummy.c} {} "pr16746a.exe"] \
+  [list "PR ld/16746 (2)" \
+   "-O2 -flto -fuse-linker-plugin tmpdir/pr16746c.o tmpdir/pr16746a.o" "-O2 -flto" \
+   {dummy.c} {} "pr16746b.exe"] \
 ]
 
 # Check final symbols in executables.
@@ -335,6 +347,20 @@ if { [is_elf_format] && [check_lto_shared_available] } {
     } {
 	fail $testname
     }
+    set testname "PR ld/16746 (3)"
+    set exec_output [run_host_cmd "$CC" "-O2 -flto -fuse-linker-plugin tmpdir/pr16746b.o tmpdir/pr16746d.o"]
+    if { [ regexp "warning: foobar" $exec_output ] && ![ regexp "symbol from plugin" $exec_output ] } {
+	pass $testname
+    } {
+	fail $testname
+    }
+    set testname "PR ld/16746 (4)"
+    set exec_output [run_host_cmd "$CC" "-O2 -flto -fuse-linker-plugin tmpdir/pr16746d.o tmpdir/pr16746b.o"]
+    if { [ regexp "warning: foobar" $exec_output ] && ![ regexp "symbol from plugin" $exec_output ] } {
+	pass $testname
+    } {
+	fail $testname
+    }
 }
 
 set testname "Build liblto-11.a"
diff --git a/ld/testsuite/ld-plugin/pr16746a.c b/ld/testsuite/ld-plugin/pr16746a.c
new file mode 100644
index 0000000..1705ef1
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr16746a.c
@@ -0,0 +1,3 @@
+static const char __evoke_link_warning_foobar[]
+ __attribute__ ((used, section (".gnu.warning.foobar\n\t#")))
+ = "foobar";
diff --git a/ld/testsuite/ld-plugin/pr16746b.c b/ld/testsuite/ld-plugin/pr16746b.c
new file mode 100644
index 0000000..c3b7a78
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr16746b.c
@@ -0,0 +1,5 @@
+static const char __evoke_link_warning_foobar[]
+ __attribute__ ((used, section (".gnu.warning.foobar\n\t#")))
+ = "foobar";
+
+void foobar (void) {}
diff --git a/ld/testsuite/ld-plugin/pr16746c.c b/ld/testsuite/ld-plugin/pr16746c.c
new file mode 100644
index 0000000..fb68ab7
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr16746c.c
@@ -0,0 +1,8 @@
+extern void foobar (void);
+int
+main (int argc, char **argv)
+{
+  if (__builtin_constant_p (argc))
+    foobar ();
+  return 0;
+}
diff --git a/ld/testsuite/ld-plugin/pr16746d.c b/ld/testsuite/ld-plugin/pr16746d.c
new file mode 100644
index 0000000..1fee4dd
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr16746d.c
@@ -0,0 +1,8 @@
+extern void foobar (void);
+int
+main (int argc, char **argv)
+{
+  if (!__builtin_constant_p (argc))
+    foobar ();
+  return 0;
+}