Use distinct maps for oddballs with special handling in the type system.

src/types.cc

 // Copyright 2014 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 "types.h"
 
 #include "string-stream.h"
 #include "types-inl.h"
 
 namespace v8 {
@@ skipping 122 matching lines @@
 int TypeImpl<Config>::LubBitset(i::Object* value) {
   if (value->IsSmi()) return kSignedSmall & kTaggedInt;
   i::Map* map = i::HeapObject::cast(value)->map();
   if (map->instance_type() == HEAP_NUMBER_TYPE) {
     int32_t i;
     uint32_t u;
     return kTaggedPtr & (
         value->ToInt32(&i) ? (Smi::IsValid(i) ? kSignedSmall : kOtherSigned32) :
         value->ToUint32(&u) ? kUnsigned32 : kFloat);
   }
-  if (map->instance_type() == ODDBALL_TYPE) {
-    if (value->IsUndefined()) return kUndefined;
-    if (value->IsNull()) return kNull;
-    if (value->IsBoolean()) return kBoolean;
-    if (value->IsTheHole()) return kAny;  // TODO(rossberg): kNone?
-    if (value->IsUninitialized()) return kNone;
-    UNREACHABLE();
-  }
   return LubBitset(map);
 }
 
 
 template<class Config>
 int TypeImpl<Config>::LubBitset(i::Map* map) {
   switch (map->instance_type()) {
     case STRING_TYPE:
     case ASCII_STRING_TYPE:
     case CONS_STRING_TYPE:
@@ skipping 10 matching lines @@
     case ASCII_INTERNALIZED_STRING_TYPE:
     case EXTERNAL_INTERNALIZED_STRING_TYPE:
     case EXTERNAL_ASCII_INTERNALIZED_STRING_TYPE:
     case EXTERNAL_INTERNALIZED_STRING_WITH_ONE_BYTE_DATA_TYPE:
     case SHORT_EXTERNAL_INTERNALIZED_STRING_TYPE:
     case SHORT_EXTERNAL_ASCII_INTERNALIZED_STRING_TYPE:
     case SHORT_EXTERNAL_INTERNALIZED_STRING_WITH_ONE_BYTE_DATA_TYPE:
       return kString;
     case SYMBOL_TYPE:
       return kSymbol;
-    case ODDBALL_TYPE:
+    case ODDBALL_TYPE: {
+      Heap* heap = map->GetHeap();
+      if (map == heap->undefined_map()) return kUndefined;
+      if (map == heap->the_hole_map()) return kAny;  // TODO(rossberg): kNone?
+      if (map == heap->null_map()) return kNull;
+      if (map == heap->boolean_map()) return kBoolean;
+      if (map == heap->uninitialized_map()) return kNone;
+      ASSERT(map == heap->oddball_map());
       return kOddball;

[rossberg, 2014/04/07 09:04:03]

I think you could now return kInternal here and eliminate the Oddball type.

[Benedikt Meurer, 2014/04/07 09:30:19]

Done.

+    }
     case HEAP_NUMBER_TYPE:
       return kFloat & kTaggedPtr;
     case JS_VALUE_TYPE:
     case JS_DATE_TYPE:
     case JS_OBJECT_TYPE:
     case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
     case JS_GENERATOR_OBJECT_TYPE:
     case JS_MODULE_TYPE:
     case JS_GLOBAL_OBJECT_TYPE:
     case JS_BUILTINS_OBJECT_TYPE:
@@ skipping 51 matching lines @@
     return kNone;
   }
 }
 
 
 // Most precise _current_ type of a value (usually its class).
 template<class Config>
 typename TypeImpl<Config>::TypeHandle TypeImpl<Config>::NowOf(
     i::Object* value, Region* region) {
   if (value->IsSmi() ||
-      i::HeapObject::cast(value)->map()->instance_type() == HEAP_NUMBER_TYPE ||
-      i::HeapObject::cast(value)->map()->instance_type() == ODDBALL_TYPE) {
+      i::HeapObject::cast(value)->map()->instance_type() == HEAP_NUMBER_TYPE) {
     return Of(value, region);
   }
   return Class(i::handle(i::HeapObject::cast(value)->map()), region);
 }
 
 
 // Check this <= that.
 template<class Config>
 bool TypeImpl<Config>::SlowIs(TypeImpl* that) {
   // Fast path for bitsets.
@@ skipping 410 matching lines @@
 template class TypeImpl<HeapTypeConfig>::Iterator<i::Object>;
 
 template TypeImpl<ZoneTypeConfig>::TypeHandle
   TypeImpl<ZoneTypeConfig>::Convert<HeapType>(
     TypeImpl<HeapTypeConfig>::TypeHandle, TypeImpl<ZoneTypeConfig>::Region*);
 template TypeImpl<HeapTypeConfig>::TypeHandle
   TypeImpl<HeapTypeConfig>::Convert<Type>(
     TypeImpl<ZoneTypeConfig>::TypeHandle, TypeImpl<HeapTypeConfig>::Region*);
 
 } }  // namespace v8::internal