re PR lto/61886 (LTO breaks fread with _FORTIFY_SOURCE=2)

	PR ipa/61886
	PR middle-end/25140
	* ipa-reference.c (is_improper): Break out from ...
	(is_proper_for_analysis): ... here; fix WRT aliases.
	(analyze_function, generate_summary,
	ipa_reference_write_optimization_summary,
	ipa_reference_read_optimization_summary): Use ipa_reference_var_uid.
	* ipa-refrence.h (ipa_reference_var_uid): New inline.
	* tree-ssa-alias.c (ref_maybe_used_by_call_p_1,
	call_may_clobber_ref_p_1): Use ipa_reference_var_uid.

	* gcc.c-torture/execute/alias-3.c: New testcase.

From-SVN: r231442

gcc/ipa-reference.c

@@ -167,8 +167,8 @@ set_reference_optimization_summary (struct cgraph_node *node,
   ipa_reference_opt_sum_vector[node->uid] = info;
 }
 
-/* Return a bitmap indexed by DECL_UID for the static variables that
-   are *not* read during the execution of the function FN.  Returns
+/* Return a bitmap indexed by ipa_reference_var_uid for the static variables
+   that are *not* read during the execution of the function FN.  Returns
    NULL if no data is available.  */
 
 bitmap
@@ -187,8 +187,8 @@ ipa_reference_get_not_read_global (struct cgraph_node *fn)
     return NULL;
 }
 
-/* Return a bitmap indexed by DECL_UID for the static variables that
-   are *not* written during the execution of the function FN.  Note
+/* Return a bitmap indexed by ipa_reference_var_uid for the static variables
+   that are *not* written during the execution of the function FN.  Note
    that variables written may or may not be read during the function
    call.  Returns NULL if no data is available.  */
 
@@ -207,40 +207,51 @@ ipa_reference_get_not_written_global (struct cgraph_node *fn)
   else
     return NULL;
 }
-
 
-/* Return true if the variable T is the right kind of static variable to
-   perform compilation unit scope escape analysis.  */
 
-static inline bool
-is_proper_for_analysis (tree t)
+/* Hepler for is_proper_for_analysis.  */
+static bool
+is_improper (symtab_node *n, void *v ATTRIBUTE_UNUSED)
 {
+  tree t = n->decl;
   /* If the variable has the "used" attribute, treat it as if it had a
      been touched by the devil.  */
   if (DECL_PRESERVE_P (t))
-    return false;
+    return true;
 
   /* Do not want to do anything with volatile except mark any
      function that uses one to be not const or pure.  */
   if (TREE_THIS_VOLATILE (t))
-    return false;
+    return true;
 
   /* We do not need to analyze readonly vars, we already know they do not
      alias.  */
   if (TREE_READONLY (t))
-    return false;
+    return true;
 
   /* We can not track variables with address taken.  */
   if (TREE_ADDRESSABLE (t))
-    return false;
+    return true;
 
-  /* TODO: We could track public variables that are not addressable, but currently
-     frontends don't give us those.  */
+  /* TODO: We could track public variables that are not addressable, but
+     currently frontends don't give us those.  */
   if (TREE_PUBLIC (t))
+    return true;
+
+  return false;
+}
+
+/* Return true if the variable T is the right kind of static variable to
+   perform compilation unit scope escape analysis.  */
+
+static inline bool
+is_proper_for_analysis (tree t)
+{
+  if (bitmap_bit_p (ignore_module_statics, ipa_reference_var_uid (t)))
     return false;
 
-  /* TODO: Check aliases.  */
-  if (bitmap_bit_p (ignore_module_statics, DECL_UID (t)))
+  if (symtab_node::get (t)
+	->call_for_symbol_and_aliases (is_improper, NULL, true))
     return false;
 
   return true;
@@ -452,21 +463,22 @@ analyze_function (struct cgraph_node *fn)
       /* This is a variable we care about.  Check if we have seen it
 	 before, and if not add it the set of variables we care about.  */
       if (all_module_statics
-	  && bitmap_set_bit (all_module_statics, DECL_UID (var)))
+	  && bitmap_set_bit (all_module_statics, ipa_reference_var_uid (var)))
 	{
 	  if (dump_file)
 	    splay_tree_insert (reference_vars_to_consider,
-			       DECL_UID (var), (splay_tree_value)var);
+			       ipa_reference_var_uid (var),
+			       (splay_tree_value)var);
 	}
       switch (ref->use)
 	{
 	case IPA_REF_LOAD:
-          bitmap_set_bit (local->statics_read, DECL_UID (var));
+          bitmap_set_bit (local->statics_read, ipa_reference_var_uid (var));
 	  break;
 	case IPA_REF_STORE:
 	  if (ref->cannot_lead_to_return ())
 	    break;
-          bitmap_set_bit (local->statics_written, DECL_UID (var));
+          bitmap_set_bit (local->statics_written, ipa_reference_var_uid (var));
 	  break;
 	case IPA_REF_ADDR:
 	  break;
@@ -547,7 +559,7 @@ generate_summary (void)
 	    var = ref->referred->decl;
 	    if (!is_proper_for_analysis (var))
 	      continue;
-	    bitmap_set_bit (ignore_module_statics, DECL_UID (var));
+	    bitmap_set_bit (ignore_module_statics, ipa_reference_var_uid (var));
 	  }
       }
   FOR_EACH_DEFINED_FUNCTION (node)
@@ -975,13 +987,15 @@ ipa_reference_write_optimization_summary (void)
       symtab_node *snode = lto_symtab_encoder_deref (encoder, i);
       varpool_node *vnode = dyn_cast <varpool_node *> (snode);
       if (vnode
-	  && bitmap_bit_p (all_module_statics, DECL_UID (vnode->decl))
+	  && bitmap_bit_p (all_module_statics,
+			    ipa_reference_var_uid (vnode->decl))
 	  && referenced_from_this_partition_p (vnode, encoder))
 	{
 	  tree decl = vnode->decl;
-	  bitmap_set_bit (ltrans_statics, DECL_UID (decl));
+	  bitmap_set_bit (ltrans_statics, ipa_reference_var_uid (decl));
 	  splay_tree_insert (reference_vars_to_consider,
-			     DECL_UID (decl), (splay_tree_value)decl);
+			     ipa_reference_var_uid (decl),
+			     (splay_tree_value)decl);
 	  ltrans_statics_bitcount ++;
 	}
     }
@@ -1067,7 +1081,8 @@ ipa_reference_read_optimization_summary (void)
 	      unsigned int var_index = streamer_read_uhwi (ib);
 	      tree v_decl = lto_file_decl_data_get_var_decl (file_data,
 							     var_index);
-	      bitmap_set_bit (all_module_statics, DECL_UID (v_decl));
+	      bitmap_set_bit (all_module_statics,
+			      ipa_reference_var_uid (v_decl));
 	      if (dump_file)
 		fprintf (dump_file, " %s", fndecl_name (v_decl));
 	    }
@@ -1107,7 +1122,8 @@ ipa_reference_read_optimization_summary (void)
 		    unsigned int var_index = streamer_read_uhwi (ib);
 		    tree v_decl = lto_file_decl_data_get_var_decl (file_data,
 								   var_index);
-		    bitmap_set_bit (info->statics_not_read, DECL_UID (v_decl));
+		    bitmap_set_bit (info->statics_not_read,
+				    ipa_reference_var_uid (v_decl));
 		    if (dump_file)
 		      fprintf (dump_file, " %s", fndecl_name (v_decl));
 		  }
@@ -1129,7 +1145,8 @@ ipa_reference_read_optimization_summary (void)
 		    unsigned int var_index = streamer_read_uhwi (ib);
 		    tree v_decl = lto_file_decl_data_get_var_decl (file_data,
 								   var_index);
-		    bitmap_set_bit (info->statics_not_written, DECL_UID (v_decl));
+		    bitmap_set_bit (info->statics_not_written,
+				    ipa_reference_var_uid (v_decl));
 		    if (dump_file)
 		      fprintf (dump_file, " %s", fndecl_name (v_decl));
 		  }

gcc/ipa-reference.h

@@ -26,5 +26,11 @@ bitmap ipa_reference_get_not_read_global (struct cgraph_node *fn);
 bitmap ipa_reference_get_not_written_global (struct cgraph_node *fn);
 void ipa_reference_c_finalize (void);
 
+inline int
+ipa_reference_var_uid (tree t)
+{
+  return DECL_UID (symtab_node::get (t)->ultimate_alias_target (NULL)->decl);
+}
+
 #endif  /* GCC_IPA_REFERENCE_H  */
 

gcc/testsuite/ChangeLog

+2015-12-08  Jan Hubicka  <hubicka@ucw.cz>
+
+	PR ipa/61886
+	PR middle-end/25140
+	* gcc.c-torture/execute/alias-3.c: New testcase.
+
 2015-12-08  Martin Sebor  <msebor@redhat.com>
 
 	PR c++/68711

gcc/testsuite/gcc.c-torture/execute/alias-3.c

+/* { dg-require-alias "" } */
+static int a=0;
+extern int b __attribute__ ((alias("a")));
+__attribute__ ((noinline))
+static inc()
+{
+  b++;
+}
+int
+main()
+{
+  a=0;
+  inc ();
+  if (a!=1)
+    __builtin_abort ();
+  return 0;
+}

gcc/tree-ssa-alias.c

@@ -1739,15 +1739,21 @@ ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *ref)
       && TREE_STATIC (base))
     {
       struct cgraph_node *node = cgraph_node::get (callee);
-      bitmap not_read;
 
       /* FIXME: Callee can be an OMP builtin that does not have a call graph
 	 node yet.  We should enforce that there are nodes for all decls in the
 	 IL and remove this check instead.  */
-      if (node
-	  && (not_read = ipa_reference_get_not_read_global (node))
-	  && bitmap_bit_p (not_read, DECL_UID (base)))
-	goto process_args;
+      if (node)
+	{
+	  enum availability avail;
+	  bitmap not_read;
+
+	  node = node->ultimate_alias_target (&avail);
+	  if (avail >= AVAIL_AVAILABLE
+	      && (not_read = ipa_reference_get_not_read_global (node))
+	      && bitmap_bit_p (not_read, ipa_reference_var_uid (base)))
+	    goto process_args;
+	}
     }
 
   /* Check if the base variable is call-used.  */
@@ -2128,12 +2134,18 @@ call_may_clobber_ref_p_1 (gcall *call, ao_ref *ref)
       && TREE_STATIC (base))
     {
       struct cgraph_node *node = cgraph_node::get (callee);
-      bitmap not_written;
 
-      if (node
-	  && (not_written = ipa_reference_get_not_written_global (node))
-	  && bitmap_bit_p (not_written, DECL_UID (base)))
-	return false;
+      if (node)
+	{
+	  bitmap not_written;
+	  enum availability avail;
+
+	  node = node->ultimate_alias_target (&avail);
+	  if (avail >= AVAIL_AVAILABLE
+	      && (not_written = ipa_reference_get_not_written_global (node))
+	      && bitmap_bit_p (not_written, ipa_reference_var_uid (base)))
+	    return false;
+	}
     }
 
   /* Check if the base variable is call-clobbered.  */