Customized support for feedback on calls to Array.

src/objects.cc

 // Copyright 2013 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 "v8.h"
 
 #include "accessors.h"
 #include "allocation-site-scopes.h"
 #include "api.h"
 #include "arguments.h"
@@ skipping 11208 matching lines @@
                   info->host()->constant_pool());
       }
     }
   }
 }
 
 
 void SharedFunctionInfo::ClearTypeFeedbackInfo() {
   FixedArray* vector = feedback_vector();
   Heap* heap = GetHeap();
-  for (int i = 0; i < vector->length(); i++) {
+  Context* context = GetIsolate()->context();
+  JSFunction* array_function = context != NULL
+      ? context->native_context()->array_function()
+      : NULL;
+  int length = vector->length();
+
+  for (int i = 0; i < length; i++) {
     Object* obj = vector->get(i);
-    if (!obj->IsAllocationSite()) {
-      vector->set(
-          i,
-          TypeFeedbackInfo::RawUninitializedSentinel(heap),
-          SKIP_WRITE_BARRIER);
+    if (obj->IsHeapObject()) {
+      InstanceType instance_type =
+          HeapObject::cast(obj)->map()->instance_type();
+      switch (instance_type) {
+        case ALLOCATION_SITE_TYPE: break;

[danno, 2014/05/22 08:20:43]

Perhaps comments here explaining why each of these cases shouldn't clear
feedback?

[mvstanton, 2014/05/22 09:29:47]

Done.

+        case JS_FUNCTION_TYPE:
+          if (obj == array_function) break;
+          // Fall through...
+        default:
+          vector->set(i, TypeFeedbackInfo::RawUninitializedSentinel(heap),
+                      SKIP_WRITE_BARRIER);
+      }
     }
   }
 }
 
 
 BailoutId Code::TranslatePcOffsetToAstId(uint32_t pc_offset) {
   DisallowHeapAllocation no_gc;
   ASSERT(kind() == FUNCTION);
   BackEdgeTable back_edges(this, &no_gc);
   for (uint32_t i = 0; i < back_edges.length(); i++) {
@@ skipping 6028 matching lines @@
 #define ERROR_MESSAGES_TEXTS(C, T) T,
   static const char* error_messages_[] = {
       ERROR_MESSAGES_LIST(ERROR_MESSAGES_TEXTS)
   };
 #undef ERROR_MESSAGES_TEXTS
   return error_messages_[reason];
 }
 
 
 } }  // namespace v8::internal