Fix symver attribute with LTO

	* cgraph.c (cgraph_node_cannot_be_local_p_1): Prevent targets of
	symver attributes to be localized.
	* ipa-visibility.c (cgraph_externally_visible_p,
	varpool_node::externally_visible_p): Likewise.
	* symtab.c (symtab_node::verify_base): Check visibility of symbol
	versions.

	* lto-common.c (read_cgraph_and_symbols): Work around binutils
	PR25424


Co-Authored-By: Xi Ruoyao <xry111@mengyan1223.wang>

From-SVN: r279566

6 files changed, 54 insertions, 7 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3b703386ddd..5d938ae09d3 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,4 +1,14 @@
 2019-12-19  Jan Hubicka  <hubicka@ucw.cz>
+	    Xi Ruoyao  <xry111@mengyan1223.wang>
+
+	* cgraph.c (cgraph_node_cannot_be_local_p_1): Prevent targets of
+	symver attributes to be localized.
+	* ipa-visibility.c (cgraph_externally_visible_p,
+	varpool_node::externally_visible_p): Likewise.
+	* symtab.c (symtab_node::verify_base): Check visibility of symbol
+	versions.
+
+2019-12-19  Jan Hubicka  <hubicka@ucw.cz>
 	    Luo Xiong Hu  <luoxhu@linux.ibm.com
 
 	* ipa-fnsummary.h (ipa_size_summary): Remove copy consturctor.
diff --git a/gcc/cgraph.c b/gcc/cgraph.c
index ba5f2767e4b..5ba33a5a0cc 100644
--- a/gcc/cgraph.c
+++ b/gcc/cgraph.c
@@ -2226,6 +2226,9 @@ cgraph_node_cannot_be_local_p_1 (cgraph_node *node, void *)
 {
   return !(!node->force_output
 	   && !node->ifunc_resolver
+	   /* Limitation of gas requires us to output targets of symver aliases
+	      as global symbols.  This is binutils PR 25295.  */
+	   && !node->symver
 	   && ((DECL_COMDAT (node->decl)
 		&& !node->forced_by_abi
 		&& !node->used_from_object_file_p ()
diff --git a/gcc/ipa-visibility.c b/gcc/ipa-visibility.c
index f470465f935..d216a54a7ab 100644
--- a/gcc/ipa-visibility.c
+++ b/gcc/ipa-visibility.c
@@ -220,6 +220,14 @@ cgraph_externally_visible_p (struct cgraph_node *node,
       && lookup_attribute ("dllexport",
 			   DECL_ATTRIBUTES (node->decl)))
     return true;
+
+  /* Limitation of gas requires us to output targets of symver aliases as
+     global symbols.  This is binutils PR 25295.  */
+  ipa_ref *ref;
+  FOR_EACH_ALIAS (node, ref)
+    if (ref->referring->symver)
+      return true;
+
   if (node->resolution == LDPR_PREVAILING_DEF_IRONLY)
     return false;
   /* When doing LTO or whole program, we can bring COMDAT functoins static.
@@ -284,14 +292,13 @@ varpool_node::externally_visible_p (void)
 			   DECL_ATTRIBUTES (decl)))
     return true;
 
-  /* See if we have linker information about symbol not being used or
-     if we need to make guess based on the declaration.
+  /* Limitation of gas requires us to output targets of symver aliases as
+     global symbols.  This is binutils PR 25295.  */
+  ipa_ref *ref;
+  FOR_EACH_ALIAS (this, ref)
+    if (ref->referring->symver)
+      return true;
 
-     Even if the linker clams the symbol is unused, never bring internal
-     symbols that are declared by user as used or externally visible.
-     This is needed for i.e. references from asm statements.   */
-  if (used_from_object_file_p ())
-    return true;
   if (resolution == LDPR_PREVAILING_DEF_IRONLY)
     return false;
 
diff --git a/gcc/lto/ChangeLog b/gcc/lto/ChangeLog
index 9f974afb123..d0b1dba740e 100644
--- a/gcc/lto/ChangeLog
+++ b/gcc/lto/ChangeLog
@@ -1,3 +1,9 @@
+2019-12-19  Jan Hubicka  <hubicka@ucw.cz>
+	    Xi Ruoyao  <xry111@mengyan1223.wang>
+
+	* lto-common.c (read_cgraph_and_symbols): Work around binutils
+	PR25424
+
 2019-12-07  Jan Hubicka  <hubicka@ucw.cz>
 
 	* lto-partition.c (lto_balanced_map): Fix printing of tp_first_run.
diff --git a/gcc/lto/lto-common.c b/gcc/lto/lto-common.c
index 76a9d9383d5..ee07730a27d 100644
--- a/gcc/lto/lto-common.c
+++ b/gcc/lto/lto-common.c
@@ -2818,6 +2818,11 @@ read_cgraph_and_symbols (unsigned nfiles, const char **fnames)
 			   IDENTIFIER_POINTER
 			     (DECL_ASSEMBLER_NAME (snode->decl)));
 	  }
+	/* Symbol versions are always used externally, but linker does not
+	   report that correctly.
+	   This is binutils PR25924.  */
+	else if (snode->symver && *res == LDPR_PREVAILING_DEF_IRONLY)
+	  snode->resolution = LDPR_PREVAILING_DEF_IRONLY_EXP;
 	else
 	  snode->resolution = *res;
       }
diff --git a/gcc/symtab.c b/gcc/symtab.c
index 10b8ed1d178..9c52192fced 100644
--- a/gcc/symtab.c
+++ b/gcc/symtab.c
@@ -1156,6 +1156,22 @@ symtab_node::verify_base (void)
       error ("node is symver but not alias");
       error_found = true;
     }
+  /* Limitation of gas requires us to output targets of symver aliases as
+     global symbols.  This is binutils PR 25295.  */
+  if (symver
+      && (!TREE_PUBLIC (get_alias_target ()->decl)
+	  || DECL_VISIBILITY (get_alias_target ()->decl) != VISIBILITY_DEFAULT))
+    {
+      error ("symver target is not exported with default visibility");
+      error_found = true;
+    }
+  if (symver
+      && (!TREE_PUBLIC (decl)
+	  || DECL_VISIBILITY (decl) != VISIBILITY_DEFAULT))
+    {
+      error ("symver is not exported with default visibility");
+      error_found = true;
+    }
   if (same_comdat_group)
     {
       symtab_node *n = same_comdat_group;