Allow for optimized code map to have zero entries.

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 <iomanip>
 #include <sstream>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 9524 matching lines @@
     if (FLAG_trace_opt) {
       PrintF("[evicting entry from optimizing code map (%s) for ", reason);
       ShortPrint();
       PrintF(" (context-independent code)]\n");
     }
   }
   if (dst != length) {
     // Always trim even when array is cleared because of heap verifier.
     GetHeap()->RightTrimFixedArray<Heap::CONCURRENT_TO_SWEEPER>(code_map,
                                                                 length - dst);
-    if (code_map->length() == kEntriesStart) ClearOptimizedCodeMap();
+    if (code_map->length() == kEntriesStart &&
+        code_map->get(kSharedCodeIndex)->IsUndefined()) {
+      ClearOptimizedCodeMap();
+    }
   }
 }
 
 
 void SharedFunctionInfo::TrimOptimizedCodeMap(int shrink_by) {
   FixedArray* code_map = FixedArray::cast(optimized_code_map());
   DCHECK(shrink_by % kEntryLength == 0);
   DCHECK(shrink_by <= code_map->length() - kEntriesStart);
   // Always trim even when array is cleared because of heap verifier.
   GetHeap()->RightTrimFixedArray<Heap::SEQUENTIAL_TO_SWEEPER>(code_map,
                                                               shrink_by);
-  if (code_map->length() == kEntriesStart) {
+  if (code_map->length() == kEntriesStart &&
+      code_map->get(kSharedCodeIndex)->IsUndefined()) {
     ClearOptimizedCodeMap();
   }
 }
 
 
 static void GetMinInobjectSlack(Map* map, void* data) {
   int slack = map->unused_property_fields();
   if (*reinterpret_cast<int*>(data) > slack) {
     *reinterpret_cast<int*>(data) = slack;
   }
@@ skipping 6337 matching lines @@
                                             Handle<Object> new_value) {
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 }  // namespace internal
 }  // namespace v8