Reuse the nonexistent handler frontend for transition handlers

src/stub-cache.cc

 // Copyright 2012 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 "src/v8.h"
 
 #include "src/api.h"
 #include "src/arguments.h"
 #include "src/ast.h"
 #include "src/code-stubs.h"
@@ skipping 785 matching lines @@
 
 Register PropertyHandlerCompiler::Frontend(Register object_reg,
                                            Handle<Name> name) {
   Label miss;
   Register reg = FrontendHeader(object_reg, name, &miss);
   FrontendFooter(name, &miss);
   return reg;
 }
 
 
-void NamedLoadHandlerCompiler::NonexistentFrontend(Handle<Name> name) {
+void PropertyHandlerCompiler::NonexistentFrontend(Handle<Name> name,
+                                                  Register scratch1,
+                                                  Register scratch2) {
   Label miss;
 
   Register holder_reg;
   Handle<Map> last_map;
   if (holder().is_null()) {
     holder_reg = receiver();
     last_map = IC::TypeToMap(*type(), isolate());
     // If |type| has null as its prototype, |holder()| is
     // Handle<JSObject>::null().
     ASSERT(last_map->prototype() == isolate()->heap()->null_value());
   } else {
     holder_reg = FrontendHeader(receiver(), name, &miss);
     last_map = handle(holder()->map());
   }
 
-  if (last_map->is_dictionary_map() && !last_map->IsJSGlobalObjectMap()) {
-    if (!name->IsUniqueName()) {
-      ASSERT(name->IsString());
-      name = factory()->InternalizeString(Handle<String>::cast(name));
+  if (last_map->is_dictionary_map()) {
+    if (last_map->IsJSGlobalObjectMap()) {
+      Handle<JSGlobalObject> global =
+          holder().is_null()
+              ? Handle<JSGlobalObject>::cast(type()->AsConstant()->Value())
+              : Handle<JSGlobalObject>::cast(holder());
+      GenerateCheckPropertyCell(masm(), global, name, scratch1, &miss);
+    } else {
+      if (!name->IsUniqueName()) {
+        ASSERT(name->IsString());
+        name = factory()->InternalizeString(Handle<String>::cast(name));
+      }
+      ASSERT(holder().is_null() ||
+             holder()->property_dictionary()->FindEntry(name) ==
+                 NameDictionary::kNotFound);
+      GenerateDictionaryNegativeLookup(masm(), &miss, holder_reg, name,
+                                       scratch1, scratch2);
     }
-    ASSERT(holder().is_null() ||
-           holder()->property_dictionary()->FindEntry(name) ==
-               NameDictionary::kNotFound);
-    GenerateDictionaryNegativeLookup(masm(), &miss, holder_reg, name,
-                                     scratch2(), scratch3());
-  }
-
-  // If the last object in the prototype chain is a global object,
-  // check that the global property cell is empty.
-  if (last_map->IsJSGlobalObjectMap()) {
-    Handle<JSGlobalObject> global =
-        holder().is_null()
-            ? Handle<JSGlobalObject>::cast(type()->AsConstant()->Value())
-            : Handle<JSGlobalObject>::cast(holder());
-    GenerateCheckPropertyCell(masm(), global, name, scratch2(), &miss);
   }
 
   FrontendFooter(name, &miss);
 }
 
 
 Handle<Code> NamedLoadHandlerCompiler::CompileLoadField(
     Handle<Name> name, FieldIndex field, Representation representation) {
   Register reg = Frontend(receiver(), name);
   GenerateLoadField(reg, field, representation);
   return GetCode(kind(), Code::FAST, name);
 }
 
 
 Handle<Code> NamedLoadHandlerCompiler::CompileLoadConstant(
     Handle<Name> name, Handle<Object> value) {
   Frontend(receiver(), name);
   GenerateLoadConstant(value);
   return GetCode(kind(), Code::FAST, name);
 }
 
 
+Handle<Code> NamedLoadHandlerCompiler::CompileLoadNonexistent(
+    Handle<Name> name) {
+  NonexistentFrontend(name, scratch2(), scratch3());
+  GenerateLoadConstant(isolate()->factory()->undefined_value());
+  return GetCode(kind(), Code::FAST, name);
+}
+
+
 Handle<Code> NamedLoadHandlerCompiler::CompileLoadCallback(
     Handle<Name> name, Handle<ExecutableAccessorInfo> callback) {
   Register reg = CallbackFrontend(receiver(), name, callback);
   GenerateLoadCallback(reg, callback);
   return GetCode(kind(), Code::FAST, name);
 }
 
 
 Handle<Code> NamedLoadHandlerCompiler::CompileLoadCallback(
     Handle<Name> name, const CallOptimization& call_optimization) {
@@ skipping 89 matching lines @@
   bool is_nonexistent = holder()->map() == transition->GetBackPointer();
   if (is_nonexistent) {
     // Find the top object.
     Handle<JSObject> last;
     PrototypeIterator iter(isolate(), holder());
     while (!iter.IsAtEnd()) {
       last = Handle<JSObject>::cast(PrototypeIterator::GetCurrent(iter));
       iter.Advance();
     }
     if (!last.is_null()) set_holder(last);
-  }
-
-  Register holder_reg = FrontendHeader(receiver(), name, &miss);
-
-  // If no property was found, and the holder (the last object in the
-  // prototype chain) is in slow mode, we need to do a negative lookup on the
-  // holder.
-  if (is_nonexistent) {
-    GenerateNegativeHolderLookup(holder_reg, name, &miss);
+    NonexistentFrontend(name, scratch1(), scratch2());

[Igor Sheludko, 2014/08/04 10:27:58]

Now this thing will generate a frontend footer with a miss case...

+  } else {
+    Frontend(receiver(), name);

[Igor Sheludko, 2014/08/04 10:27:58]

... (same here) ...

+    ASSERT(holder()->HasFastProperties());
   }
 
   GenerateStoreTransition(transition, name, receiver(), this->name(), value(),
                           scratch1(), scratch2(), scratch3(), &miss, &slow);
 
   // Handle store cache miss.
   GenerateRestoreName(&miss, name);

[Igor Sheludko, 2014/08/04 10:27:58]

... and here goes another miss case. Maybe it would be better to move
FrontendFooter() call from NonexistentFrontend() and rename the latter one to
NonexistentFrontendHeader().

   TailCallBuiltin(masm(), MissBuiltin(kind()));
 
   GenerateRestoreName(&slow, name);
   TailCallBuiltin(masm(), SlowBuiltin(kind()));
   return GetCode(kind(), Code::FAST, name);
 }
 
 
 Handle<Code> NamedStoreHandlerCompiler::CompileStoreField(LookupResult* lookup,
                                                           Handle<Name> name) {
@@ skipping 294 matching lines @@
           Handle<FunctionTemplateInfo>(
               FunctionTemplateInfo::cast(signature->receiver()));
     }
   }
 
   is_simple_api_call_ = true;
 }
 
 
 } }  // namespace v8::internal