Add more JSArray verification for --verify-heap

src/objects-debug.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/objects.h"
 
 #include "src/bootstrapper.h"
 #include "src/disasm.h"
 #include "src/disassembler.h"
 #include "src/field-type.h"
@@ skipping 754 matching lines @@
   }
 }
 
 
 void JSArray::JSArrayVerify() {
   JSObjectVerify();
   Isolate* isolate = GetIsolate();
   CHECK(length()->IsNumber() || length()->IsUndefined(isolate));
   // If a GC was caused while constructing this array, the elements
   // pointer may point to a one pointer filler map.
-  if (ElementsAreSafeToExamine()) {
-    CHECK(elements()->IsUndefined(isolate) || elements()->IsFixedArray() ||
-          elements()->IsFixedDoubleArray());
+  if (!ElementsAreSafeToExamine()) return;
+  if (elements()->IsUndefined(isolate)) return;
+  CHECK(elements()->IsFixedArray() || elements()->IsFixedDoubleArray());
+  if (!length()->IsNumber()) return;
+  // Verify that the length and the elements backing store are in sync.
+  if (length()->IsSmi() && HasFastElements()) {
+    int size = Smi::cast(length())->value();
+    // Holey / Packed backing stores might have slack or might have not been
+    // properly initialized yet.
+    CHECK(size <= elements()->length() ||
+          elements() == isolate->heap()->empty_fixed_array());
+  } else {
+    CHECK(HasDictionaryElements());
+    uint32_t size;
+    CHECK(length()->ToArrayLength(&size));
+    if (size != 0) {
+      SeededNumberDictionary* dict = SeededNumberDictionary::cast(elements());
+      // The dictionary can never have more elements than the array length.
+      CHECK(static_cast<uint32_t>(dict->NumberOfElements()) <= size);
+    }
   }
 }
 
 
 void JSSet::JSSetVerify() {
   CHECK(IsJSSet());
   JSObjectVerify();
   VerifyHeapPointer(table());
   CHECK(table()->IsOrderedHashTable() || table()->IsUndefined(GetIsolate()));
   // TODO(arv): Verify OrderedHashTable too.
@@ skipping 670 matching lines @@
 
   // Both are done at the same time.
   CHECK_EQ(new_it.done(), old_it.done());
 }
 
 
 #endif  // DEBUG
 
 }  // namespace internal
 }  // namespace v8