[PATCH, GOOGLE] Backport patch r212222 to google 4.9 branch

[PATCH, GOOGLE] Backport patch r212222 to google 4.9 branch

[Carrot Wei]

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Hi

The more strict devirtualization condition in this patch helps to fix
google bug b/19872411.

Bootstraped and regression tested on x86-64.
OK for google 4.9 branch?

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Index: ipa-devirt.c
===================================================================
--- ipa-devirt.c	(revision 223167)
+++ ipa-devirt.c	(working copy)
@@ -537,7 +537,7 @@
    Lookup this pointer and get its type.    */
 
 tree
-method_class_type (tree t)
+method_class_type (const_tree t)
 {
   tree first_parm_type = TREE_VALUE (TYPE_ARG_TYPES (t));
   gcc_assert (TREE_CODE (t) == METHOD_TYPE);
@@ -890,6 +890,31 @@
     free_polymorphic_call_targets_hash ();
 }
 
+/* Return true when TYPE contains an polymorphic type and thus is interesting
+  for devirtualization machinery.  */
+
+bool
+contains_polymorphic_type_p (const_tree type)
+{
+  type = TYPE_MAIN_VARIANT (type);
+
+  if (RECORD_OR_UNION_TYPE_P (type))
+    {
+      if (TYPE_BINFO (type)
+          && polymorphic_type_binfo_p (TYPE_BINFO (type)))
+	return true;
+      for (tree fld = TYPE_FIELDS (type); fld; fld = DECL_CHAIN (fld))
+	if (TREE_CODE (fld) == FIELD_DECL
+	    && !DECL_ARTIFICIAL (fld)
+	    && contains_polymorphic_type_p (TREE_TYPE (fld)))
+	  return true;
+      return false;
+    }
+  if (TREE_CODE (type) == ARRAY_TYPE)
+    return contains_polymorphic_type_p (TREE_TYPE (type));
+  return false;
+}
+
 /* CONTEXT->OUTER_TYPE is a type of memory object where object of EXPECTED_TYPE
    is contained at CONTEXT->OFFSET.  Walk the memory representation of
    CONTEXT->OUTER_TYPE and find the outermost class type that match
@@ -1052,7 +1077,8 @@
    Return false if T does not look like virtual table reference.  */
 
 bool
-vtable_pointer_value_to_vtable (tree t, tree *v, unsigned HOST_WIDE_INT *offset)
+vtable_pointer_value_to_vtable (const_tree t, tree *v,
+				unsigned HOST_WIDE_INT *offset)
 {
   /* We expect &MEM[(void *)&virtual_table + 16B].
      We obtain object's BINFO from the context of the virtual table. 
@@ -1098,7 +1124,7 @@
    instance type.  */
 
 tree
-vtable_pointer_value_to_binfo (tree t)
+vtable_pointer_value_to_binfo (const_tree t)
 {
   tree vtable;
   unsigned HOST_WIDE_INT offset;
Index: ipa-prop.c
===================================================================
--- ipa-prop.c	(revision 223167)
+++ ipa-prop.c	(working copy)
@@ -394,11 +394,10 @@
 ipa_set_jf_known_type (struct ipa_jump_func *jfunc, HOST_WIDE_INT offset,
 		       tree base_type, tree component_type)
 {
-  gcc_assert (TREE_CODE (component_type) == RECORD_TYPE
-	      && TYPE_BINFO (component_type));
+  gcc_assert (contains_polymorphic_type_p (base_type)
+	      && contains_polymorphic_type_p (component_type));
   if (!flag_devirtualize)
     return;
-  gcc_assert (BINFO_VTABLE (TYPE_BINFO (component_type)));
   jfunc->type = IPA_JF_KNOWN_TYPE;
   jfunc->value.known_type.offset = offset,
   jfunc->value.known_type.base_type = base_type;
@@ -485,10 +484,9 @@
 {
   if (!flag_devirtualize)
     type_preserved = false;
-  gcc_assert (!type_preserved
-	      || (TREE_CODE (type) == RECORD_TYPE
-		  && TYPE_BINFO (type)
-		  && BINFO_VTABLE (TYPE_BINFO (type))));
+  if (!type_preserved)
+    type = NULL_TREE;
+  gcc_assert (!type_preserved || contains_polymorphic_type_p (type));
   jfunc->type = IPA_JF_ANCESTOR;
   jfunc->value.ancestor.formal_id = formal_id;
   jfunc->value.ancestor.offset = offset;
@@ -689,16 +687,10 @@
   gcc_checking_assert (DECL_P (arg)
 		       || TREE_CODE (arg) == MEM_REF
 		       || handled_component_p (arg));
-  /* Const calls cannot call virtual methods through VMT and so type changes do
-     not matter.  */
-  if (!flag_devirtualize || !gimple_vuse (call)
-      /* Be sure expected_type is polymorphic.  */
-      || !comp_type
-      || TREE_CODE (comp_type) != RECORD_TYPE
-      || !TYPE_BINFO (comp_type)
-      || !BINFO_VTABLE (TYPE_BINFO (comp_type)))
-    return true;
 
+  if (!flag_devirtualize)
+    return false;
+
   /* C++ methods are not allowed to change THIS pointer unless they
      are constructors or destructors.  */
   if (TREE_CODE	(base) == MEM_REF
@@ -710,8 +702,21 @@
       && !DECL_CXX_DESTRUCTOR_P (current_function_decl)
       && (SSA_NAME_VAR (TREE_OPERAND (base, 0))
 	  == DECL_ARGUMENTS (current_function_decl)))
-    return false;
+    {
+      gcc_assert (comp_type);
+      return false;
+    }
 
+  /* Const calls cannot call virtual methods through VMT and so type changes do
+     not matter.  */
+  if (!flag_devirtualize || !gimple_vuse (call)
+      /* Be sure expected_type is polymorphic.  */
+      || !comp_type
+      || TREE_CODE (comp_type) != RECORD_TYPE
+      || !TYPE_BINFO (TYPE_MAIN_VARIANT (comp_type))
+      || !BINFO_VTABLE (TYPE_BINFO (TYPE_MAIN_VARIANT (comp_type))))
+    return true;
+
   ao_ref_init (&ao, arg);
   ao.base = base;
   ao.offset = offset;
@@ -1111,8 +1116,9 @@
   index = ipa_get_param_decl_index (info, SSA_NAME_VAR (ssa));
   if (index >= 0 && param_type && POINTER_TYPE_P (param_type))
     {
-      bool type_p = !detect_type_change (op1, base, TREE_TYPE (param_type),
-					 call, jfunc, offset);
+      bool type_p = (contains_polymorphic_type_p (TREE_TYPE (param_type))
+		     && !detect_type_change (op1, base, TREE_TYPE (param_type),
+					     call, jfunc, offset));
       if (type_p || jfunc->type == IPA_JF_UNKNOWN)
 	ipa_set_ancestor_jf (jfunc, offset,
 			     type_p ? TREE_TYPE (param_type) : NULL, index,
@@ -1244,7 +1250,8 @@
     }
 
   bool type_p = false;
-  if (param_type && POINTER_TYPE_P (param_type))
+  if (param_type && POINTER_TYPE_P (param_type)
+      && contains_polymorphic_type_p (TREE_TYPE (param_type)))
     type_p = !detect_type_change (obj, expr, TREE_TYPE (param_type),
 				  call, jfunc, offset);
   if (type_p || jfunc->type == IPA_JF_UNKNOWN)
@@ -1267,12 +1274,10 @@
 
   if (!flag_devirtualize
       || TREE_CODE (op) != ADDR_EXPR
-      || TREE_CODE (TREE_TYPE (TREE_TYPE (op))) != RECORD_TYPE
+      || !contains_polymorphic_type_p (TREE_TYPE (TREE_TYPE (op)))
       /* Be sure expected_type is polymorphic.  */
       || !expected_type
-      || TREE_CODE (expected_type) != RECORD_TYPE
-      || !TYPE_BINFO (expected_type)
-      || !BINFO_VTABLE (TYPE_BINFO (expected_type)))
+      || !contains_polymorphic_type_p (expected_type))
     return;
 
   op = TREE_OPERAND (op, 0);
@@ -1280,7 +1285,7 @@
   if (!DECL_P (base)
       || max_size == -1
       || max_size != size
-      || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE
+      || !contains_polymorphic_type_p (TREE_TYPE (base))
       || is_global_var (base))
     return;
 
Index: ipa-utils.h
===================================================================
--- ipa-utils.h	(revision 223167)
+++ ipa-utils.h	(working copy)
@@ -87,15 +87,16 @@
 					     const ipa_polymorphic_call_context &);
 bool possible_polymorphic_call_target_p (tree, HOST_WIDE_INT,
 				         const ipa_polymorphic_call_context &,
-					 struct cgraph_node *n);
-tree method_class_type (tree);
+					 struct cgraph_node *);
+tree method_class_type (const_tree);
 tree get_polymorphic_call_info (tree, tree, tree *,
 				HOST_WIDE_INT *,
 				ipa_polymorphic_call_context *);
 bool get_polymorphic_call_info_from_invariant (ipa_polymorphic_call_context *,
 					       tree, tree, HOST_WIDE_INT);
-tree vtable_pointer_value_to_binfo (tree t);
-bool vtable_pointer_value_to_vtable (tree, tree *, unsigned HOST_WIDE_INT *);
+tree vtable_pointer_value_to_binfo (const_tree);
+bool vtable_pointer_value_to_vtable (const_tree, tree *, unsigned HOST_WIDE_INT *);
+bool contains_polymorphic_type_p (const_tree);
 
 /* Return vector containing possible targets of polymorphic call E.
    If FINALP is non-NULL, store true if the list is complette. 

Re: [PATCH, GOOGLE] Backport patch r212222 to google 4.9 branch

[Xinliang David Li]

ok.

David

On Wed, May 13, 2015 at 11:00 AM, Carrot Wei <carrot@google.com> wrote:
> Hi
>
> The more strict devirtualization condition in this patch helps to fix
> google bug b/19872411.
>
> Bootstraped and regression tested on x86-64.
> OK for google 4.9 branch?