[TypeFeedbackVector] special ic slots for interpreter compare/binary ops.

src/code-stub-assembler.cc

 // Copyright 2016 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/code-stub-assembler.h"
 #include "src/code-factory.h"
 #include "src/frames-inl.h"
 #include "src/frames.h"
 #include "src/ic/handler-configuration.h"
 #include "src/ic/stub-cache.h"
@@ skipping 3564 matching lines @@
       LoadFromParentFrame(JavaScriptFrameConstants::kFunctionOffset);
   Node* literals = LoadObjectField(function, JSFunction::kLiteralsOffset);
   return LoadObjectField(literals, LiteralsArray::kFeedbackVectorOffset);
 }
 
 void CodeStubAssembler::UpdateFeedback(compiler::Node* feedback,
                                        compiler::Node* type_feedback_vector,
                                        compiler::Node* slot_id) {
   Label combine_feedback(this), record_feedback(this), end(this);
 
+  // This method is used for binary op and compare feedback. These
+  // vector nodes are initialized with a smi 0, so we can simply OR
+  // our new feedback in place.
   Node* previous_feedback =
       LoadFixedArrayElement(type_feedback_vector, slot_id);
-  Node* is_uninitialized = WordEqual(
-      previous_feedback,
-      HeapConstant(TypeFeedbackVector::UninitializedSentinel(isolate())));
-  BranchIf(is_uninitialized, &record_feedback, &combine_feedback);
-
-  Bind(&record_feedback);
-  {
-    StoreFixedArrayElement(type_feedback_vector, slot_id, SmiTag(feedback),
-                           SKIP_WRITE_BARRIER);
-    Goto(&end);
-  }
-
-  Bind(&combine_feedback);
-  {
-    Node* untagged_previous_feedback = SmiUntag(previous_feedback);
-    Node* combined_feedback = Word32Or(untagged_previous_feedback, feedback);
-    StoreFixedArrayElement(type_feedback_vector, slot_id,
-                           SmiTag(combined_feedback), SKIP_WRITE_BARRIER);
-    Goto(&end);
-  }
-
-  Bind(&end);
+  Node* untagged_previous_feedback = SmiUntag(previous_feedback);
+  Node* combined_feedback = Word32Or(untagged_previous_feedback, feedback);
+  StoreFixedArrayElement(type_feedback_vector, slot_id,
+                         SmiTag(combined_feedback), SKIP_WRITE_BARRIER);
 }
 
 compiler::Node* CodeStubAssembler::LoadReceiverMap(compiler::Node* receiver) {
   Variable var_receiver_map(this, MachineRepresentation::kTagged);
   // TODO(ishell): defer blocks when it works.
   Label load_smi_map(this /*, Label::kDeferred*/), load_receiver_map(this),
       if_result(this);
 
   Branch(WordIsSmi(receiver), &load_smi_map, &load_receiver_map);
   Bind(&load_smi_map);
@@ skipping 1518 matching lines @@
                        Heap::kTheHoleValueRootIndex);
 
   // Store the WeakCell in the feedback vector.
   StoreFixedArrayElement(feedback_vector, slot, cell, UPDATE_WRITE_BARRIER,
                          CodeStubAssembler::SMI_PARAMETERS);
   return cell;
 }
 
 }  // namespace internal
 }  // namespace v8