Add --trace-array-abuse to help find OOB accesses.

src/objects.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 10387 matching lines @@
 MaybeObject* JSObject::SetElementWithoutInterceptor(uint32_t index,
                                                     Object* value,
                                                     PropertyAttributes attr,
                                                     StrictModeFlag strict_mode,
                                                     bool check_prototype,
                                                     SetPropertyMode set_mode) {
   ASSERT(HasDictionaryElements() ||
          HasDictionaryArgumentsElements() ||
          (attr & (DONT_DELETE | DONT_ENUM | READ_ONLY)) == 0);
   Isolate* isolate = GetIsolate();
+  if (FLAG_trace_array_abuse) {
+    if (IsExternalArrayElementsKind(GetElementsKind())) {
+      CheckArrayAbuse(this, "external elements write", index);
+    }
+  }
   switch (GetElementsKind()) {
     case FAST_SMI_ELEMENTS:
     case FAST_ELEMENTS:
     case FAST_HOLEY_SMI_ELEMENTS:
     case FAST_HOLEY_ELEMENTS:
       return SetFastElement(index, value, strict_mode, check_prototype);
     case FAST_DOUBLE_ELEMENTS:
     case FAST_HOLEY_DOUBLE_ELEMENTS:
       return SetFastDoubleElement(index, value, strict_mode, check_prototype);
     case EXTERNAL_PIXEL_ELEMENTS: {
@@ skipping 3474 matching lines @@
   set_year(Smi::FromInt(year), SKIP_WRITE_BARRIER);
   set_month(Smi::FromInt(month), SKIP_WRITE_BARRIER);
   set_day(Smi::FromInt(day), SKIP_WRITE_BARRIER);
   set_weekday(Smi::FromInt(weekday), SKIP_WRITE_BARRIER);
   set_hour(Smi::FromInt(hour), SKIP_WRITE_BARRIER);
   set_min(Smi::FromInt(min), SKIP_WRITE_BARRIER);
   set_sec(Smi::FromInt(sec), SKIP_WRITE_BARRIER);
 }
 
 } }  // namespace v8::internal