Track up to 5 stable maps as field type.

src/types.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "types.h"
 
 #include "string-stream.h"
 #include "types-inl.h"
 
 namespace v8 {
@@ skipping 341 matching lines @@
       i::Map* map = i::HeapObject::cast(object)->map();
       for (Iterator<i::Map> it = that->Classes(); !it.Done(); it.Advance()) {
         if (*it.Current() == map) return true;
       }
     }
   }
   return this->Is(that);
 }
 
 
+// Check if this contains only (currently) stable classes.
+template<class Config>
+bool TypeImpl<Config>::NowStable() {
+  DisallowHeapAllocation no_allocation;
+  for (Iterator<i::Map> it = this->Classes(); !it.Done(); it.Advance()) {
+    if (!it.Current()->is_stable()) return false;
+  }
+  return true;
+}
+
+
 // Check this overlaps that.
 template<class Config>
 bool TypeImpl<Config>::Maybe(TypeImpl* that) {
   DisallowHeapAllocation no_allocation;
 
   // (T1 \/ ... \/ Tn) overlaps T <=> (T1 overlaps T) \/ ... \/ (Tn overlaps T)
   if (this->IsUnion()) {
     UnionHandle unioned = handle(this->AsUnion());
     for (int i = 0; i < unioned->Length(); ++i) {
       if (unioned->Get(i)->Maybe(that)) return true;
@@ skipping 389 matching lines @@
 template class TypeImpl<HeapTypeConfig>::Iterator<i::Object>;
 
 template TypeImpl<ZoneTypeConfig>::TypeHandle
   TypeImpl<ZoneTypeConfig>::Convert<HeapType>(
     TypeImpl<HeapTypeConfig>::TypeHandle, TypeImpl<ZoneTypeConfig>::Region*);
 template TypeImpl<HeapTypeConfig>::TypeHandle
   TypeImpl<HeapTypeConfig>::Convert<Type>(
     TypeImpl<ZoneTypeConfig>::TypeHandle, TypeImpl<HeapTypeConfig>::Region*);
 
 } }  // namespace v8::internal