[ic] Simplify handling of primitive maps.

src/ic/arm/handler-compiler-arm.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.
 
 #if V8_TARGET_ARCH_ARM
 
 #include "src/ic/handler-compiler.h"
 
 #include "src/api-arguments.h"
 #include "src/field-type.h"
@@ skipping 389 matching lines @@
   DCHECK(!value_reg.is(scratch));
   __ JumpIfSmi(value_reg, miss_label);
   if (field_type->IsClass()) {
     __ ldr(map_reg, FieldMemOperand(value_reg, HeapObject::kMapOffset));
     __ CmpWeakValue(map_reg, Map::WeakCellForMap(field_type->AsClass()),
                     scratch);
     __ b(ne, miss_label);
   }
 }
 
-
 Register PropertyHandlerCompiler::CheckPrototypes(
     Register object_reg, Register holder_reg, Register scratch1,
-    Register scratch2, Handle<Name> name, Label* miss, PrototypeCheckType check,
+    Register scratch2, Handle<Name> name, Label* miss,
     ReturnHolder return_what) {
   Handle<Map> receiver_map = map();
 
   // Make sure there's no overlap between holder and object registers.
   DCHECK(!scratch1.is(object_reg) && !scratch1.is(holder_reg));
   DCHECK(!scratch2.is(object_reg) && !scratch2.is(holder_reg) &&
          !scratch2.is(scratch1));
 
   Handle<Cell> validity_cell =
       Map::GetOrCreatePrototypeChainValidityCell(receiver_map, isolate());
   if (!validity_cell.is_null()) {
     DCHECK_EQ(Smi::FromInt(Map::kPrototypeChainValid), validity_cell->value());
     __ mov(scratch1, Operand(validity_cell));
     __ ldr(scratch1, FieldMemOperand(scratch1, Cell::kValueOffset));
     __ cmp(scratch1, Operand(Smi::FromInt(Map::kPrototypeChainValid)));
     __ b(ne, miss);
   }
 
-  // The prototype chain of primitives (and their JSValue wrappers) depends
-  // on the native context, which can't be guarded by validity cells.
-  // |object_reg| holds the native context specific prototype in this case;
-  // we need to check its map.
-  if (check == CHECK_ALL_MAPS) {
-    __ ldr(scratch1, FieldMemOperand(object_reg, HeapObject::kMapOffset));
-    Handle<WeakCell> cell = Map::WeakCellForMap(receiver_map);
-    __ CmpWeakValue(scratch1, cell, scratch2);
-    __ b(ne, miss);
-  }
-
   // Keep track of the current object in register reg.
   Register reg = object_reg;
   int depth = 0;
 
   Handle<JSObject> current = Handle<JSObject>::null();
   if (receiver_map->IsJSGlobalObjectMap()) {
     current = isolate()->global_object();
   }
 
-  Handle<JSObject> prototype = Handle<JSObject>::null();
-  Handle<Map> current_map = receiver_map;
+  Handle<Map> current_map(receiver_map->GetPrototypeChainRootMap(isolate()),
+                          isolate());
   Handle<Map> holder_map(holder()->map());
   // Traverse the prototype chain and check the maps in the prototype chain for
   // fast and global objects or do negative lookup for normal objects.
   while (!current_map.is_identical_to(holder_map)) {
     ++depth;
 
-    prototype = handle(JSObject::cast(current_map->prototype()));
     if (current_map->IsJSGlobalObjectMap()) {
       GenerateCheckPropertyCell(masm(), Handle<JSGlobalObject>::cast(current),
                                 name, scratch2, miss);
     } else if (current_map->is_dictionary_map()) {
       DCHECK(!current_map->IsJSGlobalProxyMap());  // Proxy maps are fast.
       DCHECK(name->IsUniqueName());
       DCHECK(current.is_null() ||
              current->property_dictionary()->FindEntry(name) ==
                  NameDictionary::kNotFound);
 
       if (depth > 1) {
         Handle<WeakCell> weak_cell =
             Map::GetOrCreatePrototypeWeakCell(current, isolate());
         __ LoadWeakValue(reg, weak_cell, miss);
       }
       GenerateDictionaryNegativeLookup(masm(), miss, reg, name, scratch1,
                                        scratch2);
     }
 
     reg = holder_reg;  // From now on the object will be in holder_reg.
     // Go to the next object in the prototype chain.
-    current = prototype;
+    current = handle(JSObject::cast(current_map->prototype()));
     current_map = handle(current->map());
   }
 
   DCHECK(!current_map->IsJSGlobalProxyMap());
 
   // Log the check depth.
   LOG(isolate(), IntEvent("check-maps-depth", depth + 1));
 
   bool return_holder = return_what == RETURN_HOLDER;
   if (return_holder && depth != 0) {
@@ skipping 181 matching lines @@
   // Return the generated code.
   return GetCode(kind(), name);
 }
 
 
 #undef __
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM