--- a/gcc/symtab.c	Fri Oct 27 22:46:09 2017 +0900
+++ b/gcc/symtab.c	Thu Oct 25 07:37:49 2018 +0900
@@ -1,5 +1,5 @@
 /* Symbol table.
-   Copyright (C) 2012-2017 Free Software Foundation, Inc.
+   Copyright (C) 2012-2018 Free Software Foundation, Inc.
    Contributed by Jan Hubicka
 
 This file is part of GCC.
@@ -37,8 +37,9 @@
 #include "calls.h"
 #include "stringpool.h"
 #include "attribs.h"
+#include "builtins.h"
 
-static const char *ipa_ref_use_name[] = {"read","write","addr","alias","chkp"};
+static const char *ipa_ref_use_name[] = {"read","write","addr","alias"};
 
 const char * const ld_plugin_symbol_resolution_names[]=
 {
@@ -946,6 +947,12 @@
     node->dump (f);
 }
 
+DEBUG_FUNCTION void
+symbol_table::debug (void)
+{
+  dump (stderr);
+}
+
 /* Return the cgraph node that has ASMNAME for its DECL_ASSEMBLER_NAME.
    Return NULL if there's no such node.  */
 
@@ -991,6 +998,13 @@
           error ("function symbol is not function");
           error_found = true;
 	}
+      else if ((lookup_attribute ("ifunc", DECL_ATTRIBUTES (decl))
+		!= NULL)
+	       != dyn_cast <cgraph_node *> (this)->ifunc_resolver)
+	{
+          error ("inconsistent `ifunc' attribute");
+          error_found = true;
+	}
     }
   else if (is_a <varpool_node *> (this))
     {
@@ -1945,11 +1959,11 @@
       return true;
     }
 
-  /* If target is defined and not extern, we know it will be output and thus
-     it will bind to non-NULL.
-     Play safe for flag_delete_null_pointer_checks where weak definition maye
+  /* If target is defined and either comdat or not extern, we know it will be
+     output and thus it will bind to non-NULL.
+     Play safe for flag_delete_null_pointer_checks where weak definition may
      be re-defined by NULL.  */
-  if (definition && !DECL_EXTERNAL (decl)
+  if (definition && (!DECL_EXTERNAL (decl) || DECL_COMDAT (decl))
       && (flag_delete_null_pointer_checks || !DECL_WEAK (decl)))
     {
       if (!DECL_WEAK (decl))
@@ -2191,7 +2205,7 @@
 void
 symtab_node::increase_alignment (unsigned int align)
 {
-  gcc_assert (can_increase_alignment_p () && align < MAX_OFILE_ALIGNMENT);
+  gcc_assert (can_increase_alignment_p () && align <= MAX_OFILE_ALIGNMENT);
   ultimate_alias_target()->call_for_symbol_and_aliases (increase_alignment_1,
 						        (void *)(size_t) align,
 						        true);
@@ -2246,13 +2260,13 @@
   if (transparent_alias)
     return definition
 	   && get_alias_target()->binds_to_current_def_p (ref);
-  if (lookup_attribute ("ifunc", DECL_ATTRIBUTES (decl)))
+  cgraph_node *cnode = dyn_cast <cgraph_node *> (this);
+  if (cnode && cnode->ifunc_resolver)
     return false;
   if (decl_binds_to_current_def_p (decl))
     return true;
 
   /* Inline clones always binds locally.  */
-  cgraph_node *cnode = dyn_cast <cgraph_node *> (this);
   if (cnode && cnode->global.inlined_to)
     return true;
 
@@ -2292,3 +2306,58 @@
 
   return false;
 }
+
+/* Return true if symbol should be output to the symbol table.  */
+
+bool
+symtab_node::output_to_lto_symbol_table_p (void)
+{
+  /* Only externally visible symbols matter.  */
+  if (!TREE_PUBLIC (decl))
+    return false;
+  if (!real_symbol_p ())
+    return false;
+  /* FIXME: variables probably should not be considered as real symbols at
+     first place.  */
+  if (VAR_P (decl) && DECL_HARD_REGISTER (decl))
+    return false;
+  /* FIXME: Builtins corresponding to real functions probably should have
+     symbol table entries.  */
+  if (TREE_CODE (decl) == FUNCTION_DECL && fndecl_built_in_p (decl))
+    return false;
+
+  /* We have real symbol that should be in symbol table.  However try to trim
+     down the refernces to libraries bit more because linker will otherwise
+     bring unnecesary object files into the final link.
+     FIXME: The following checks can easily be confused i.e. by self recursive
+     function or self-referring variable.  */
+
+  /* We keep external functions in symtab for sake of inlining
+     and devirtualization.  We do not want to see them in symbol table as
+     references unless they are really used.  */
+  cgraph_node *cnode = dyn_cast <cgraph_node *> (this);
+  if (cnode && (!definition || DECL_EXTERNAL (decl))
+      && cnode->callers)
+    return true;
+
+ /* Ignore all references from external vars initializers - they are not really
+    part of the compilation unit until they are used by folding.  Some symbols,
+    like references to external construction vtables can not be referred to at
+    all.  We decide this at can_refer_decl_in_current_unit_p.  */
+ if (!definition || DECL_EXTERNAL (decl))
+    {
+      int i;
+      struct ipa_ref *ref;
+      for (i = 0; iterate_referring (i, ref); i++)
+	{
+	  if (ref->use == IPA_REF_ALIAS)
+	    continue;
+          if (is_a <cgraph_node *> (ref->referring))
+	    return true;
+	  if (!DECL_EXTERNAL (ref->referring->decl))
+	    return true;
+	}
+      return false;
+    }
+  return true;
+}