Remove prototype checks for leaf maps in optimized code.

src/objects-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3406 matching lines @@
          instance_type() > LAST_JS_OBJECT_TYPE ||
          has_slow_elements_kind() || has_external_array_elements());
   set_bit_field3(IsObserved::update(bit_field3(), is_observed));
 }
 
 
 bool Map::is_observed() {
   return IsObserved::decode(bit_field3());
 }
 
+void Map::NotifyObjectLayoutChange() {
+  DeoptimizeDependentCodes(DependentCodes::kPrototypeCheckGroup);
+}
+
+bool Map::CanOmitPrototypeChecks() {
+  return !HasTransitionArray() && !is_dictionary_map();
+}
 
 void Map::AddDependentCode(DependentCodes::DependencyGroup group,
                            Handle<Code> code) {
   Handle<DependentCodes> codes =
       DependentCodes::Insert(Handle<DependentCodes>(dependent_codes()),
                              group, code);
   if (*codes != dependent_codes()) {
     set_dependent_codes(*codes);
   }
 }
@@ skipping 24 matching lines @@
   return HeapObject::RawField(
       this, FixedArray::OffsetOfElementAt(kCodesStartIndex + i));
 }
 
 
 void DependentCodes::clear_code_at(int i) {
   set_undefined(kCodesStartIndex + i);
 }
 
 
-void DependentCodes::ComputeGroupStartIndexes(GroupStartIndexes starts) {
-  starts[0] = 0;
-  for (int g = 1; g <= kGroupCount; g++) {
-    int count = number_of_codes(static_cast<DependencyGroup>(g - 1));
-    starts[g] = starts[g - 1] + count;
-  }
-}
-
-
 void DependentCodes::ExtendGroup(DependencyGroup group) {
-  GroupStartIndexes starts;
-  ComputeGroupStartIndexes(starts);
-  for (int g = kGroupCount - 2; g > group; g--) {
-    set_code_at(starts[g + 1], code_at(starts[g]));
+  GroupStartIndexes starts(this);
+  for (int g = kGroupCount - 1; g > group; g--) {
+    if (starts.at(g) < starts.at(g + 1)) {
+      set_code_at(starts.at(g + 1), code_at(starts.at(g)));
+    }
   }
 }
 
 
 void Code::set_flags(Code::Flags flags) {
   STATIC_ASSERT(Code::NUMBER_OF_KINDS <= KindField::kMax + 1);
   // Make sure that all call stubs have an arguments count.
   ASSERT((ExtractKindFromFlags(flags) != CALL_IC &&
           ExtractKindFromFlags(flags) != KEYED_CALL_IC) ||
          ExtractArgumentsCountFromFlags(flags) >= 0);
@@ skipping 2415 matching lines @@
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_