Per-Isolate cache for polymorphic stubs

BUG=1385
TEST=Existing tests still pass; running d8 with --dump-counters shows fewer polymorphic stubs being compiled

Review URL: http://codereview.chromium.org/7094003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8183 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -3703,7 +3703,7 @@ class Internals {
   static const int kFullStringRepresentationMask = 0x07;
   static const int kExternalTwoByteRepresentationTag = 0x02;
 
-  static const int kJSObjectType = 0xa1;
+  static const int kJSObjectType = 0xa2;
   static const int kFirstNonstringType = 0x80;
   static const int kForeignType = 0x85;
 

src/heap.cc

@@ -877,6 +877,9 @@ void Heap::MarkCompactPrologue(bool is_compacting) {
   CompletelyClearInstanceofCache();
 
   if (is_compacting) FlushNumberStringCache();
+  if (FLAG_cleanup_code_caches_at_gc) {
+    polymorphic_code_cache()->set_cache(undefined_value());
+  }
 
   ClearNormalizedMapCaches();
 }
@@ -1661,6 +1664,11 @@ MaybeObject* Heap::AllocateCodeCache() {
 }
 
 
+MaybeObject* Heap::AllocatePolymorphicCodeCache() {
+  return AllocateStruct(POLYMORPHIC_CODE_CACHE_TYPE);
+}
+
+
 const Heap::StringTypeTable Heap::string_type_table[] = {
 #define STRING_TYPE_ELEMENT(type, size, name, camel_name)                      \
   {type, size, k##camel_name##MapRootIndex},
@@ -2168,6 +2176,11 @@ bool Heap::CreateInitialObjects() {
   }
   set_non_monomorphic_cache(NumberDictionary::cast(obj));
 
+  { MaybeObject* maybe_obj = AllocatePolymorphicCodeCache();
+    if (!maybe_obj->ToObject(&obj)) return false;
+  }
+  set_polymorphic_code_cache(PolymorphicCodeCache::cast(obj));
+
   set_instanceof_cache_function(Smi::FromInt(0));
   set_instanceof_cache_map(Smi::FromInt(0));
   set_instanceof_cache_answer(Smi::FromInt(0));

src/heap.h

@@ -120,6 +120,7 @@ inline Heap* _inline_get_heap_();
   V(Foreign, prototype_accessors, PrototypeAccessors)                          \
   V(NumberDictionary, code_stubs, CodeStubs)                                   \
   V(NumberDictionary, non_monomorphic_cache, NonMonomorphicCache)              \
+  V(PolymorphicCodeCache, polymorphic_code_cache, PolymorphicCodeCache)        \
   V(Code, js_entry_code, JsEntryCode)                                          \
   V(Code, js_construct_entry_code, JsConstructEntryCode)                       \
   V(FixedArray, natives_source_cache, NativesSourceCache)                      \
@@ -477,6 +478,9 @@ class Heap {
   // Allocates an empty code cache.
   MUST_USE_RESULT MaybeObject* AllocateCodeCache();
 
+  // Allocates an empty PolymorphicCodeCache.
+  MUST_USE_RESULT MaybeObject* AllocatePolymorphicCodeCache();
+
   // Clear the Instanceof cache (used when a prototype changes).
   inline void ClearInstanceofCache();
 

src/ic.cc

@@ -1636,79 +1636,40 @@ MaybeObject* KeyedIC::ComputeStub(JSObject* receiver,
     return generic_stub;
   }
 
-  // TODO(1385): Currently MEGAMORPHIC stubs are cached in the receiver map stub
-  // cache, but that can put receiver types together from unrelated call sites
-  // into the same stub--they always handle the union of all receiver maps seen
-  // at all call sites involving the receiver map. This is only an
-  // approximation: ideally, there would be a global cache that mapped sets of
-  // receiver maps to MEGAMORPHIC stubs. The complexity of the MEGAMORPHIC stub
-  // computation also leads to direct manipulation of the stub cache from the IC
-  // code, which the global cache solution would avoid.
-  Code::Kind kind = this->kind();
-  Code::Flags flags = Code::ComputeFlags(kind,
-                                         NOT_IN_LOOP,
-                                         MEGAMORPHIC,
-                                         strict_mode);
-  String* megamorphic_name = GetStubNameForCache(MEGAMORPHIC);
-  Object* maybe_cached_stub = receiver->map()->FindInCodeCache(megamorphic_name,
-                                                               flags);
-
-  // Create a set of all receiver maps that have been seen at the IC call site
-  // and those seen by the MEGAMORPHIC cached stub, if that's the stub that's
-  // been selected.
-  MapList receiver_maps;
-  if (!maybe_cached_stub->IsUndefined()) {
-    GetReceiverMapsForStub(Code::cast(maybe_cached_stub), &receiver_maps);
-  }
-  bool added_map = false;
-  for (int i = 0; i < target_receiver_maps.length(); ++i) {
-    if (AddOneReceiverMapIfMissing(&receiver_maps,
-                                   target_receiver_maps.at(i))) {
-      added_map = true;
-    }
-  }
-  ASSERT(receiver_maps.length() > 0);
-
-  // If the maximum number of receiver maps has been exceeded, use the Generic
+  // If the maximum number of receiver maps has been exceeded, use the generic
   // version of the IC.
-  if (receiver_maps.length() > KeyedIC::kMaxKeyedPolymorphism) {
+  if (target_receiver_maps.length() > KeyedIC::kMaxKeyedPolymorphism) {
     return generic_stub;
   }
 
-  // If no maps have been seen at the call site that aren't in the cached
-  // stub, then use it.
-  if (!added_map) {
-    ASSERT(!maybe_cached_stub->IsUndefined());
+  PolymorphicCodeCache* cache = isolate()->heap()->polymorphic_code_cache();
+  Code::Flags flags = Code::ComputeFlags(this->kind(),
+                                         NOT_IN_LOOP,
+                                         MEGAMORPHIC,
+                                         strict_mode);
+  Object* maybe_cached_stub = cache->Lookup(&target_receiver_maps, flags);
+  // If there is a cached stub, use it.
+  if (!maybe_cached_stub->IsUndefined()) {
     ASSERT(maybe_cached_stub->IsCode());
     return Code::cast(maybe_cached_stub);
   }
-
-  // Lookup all of the receiver maps in the cache, they should all already
-  // have MONOMORPHIC stubs.
-  CodeList handler_ics(KeyedIC::kMaxKeyedPolymorphism);
-  for (int current = 0; current < receiver_maps.length(); ++current) {
-    Map* receiver_map(receiver_maps.at(current));
+  // Collect MONOMORPHIC stubs for all target_receiver_maps.
+  CodeList handler_ics(target_receiver_maps.length());
+  for (int i = 0; i < target_receiver_maps.length(); ++i) {
+    Map* receiver_map(target_receiver_maps.at(i));
     MaybeObject* maybe_cached_stub = ComputeMonomorphicStubWithoutMapCheck(
-        receiver_map,
-        strict_mode,
-        generic_stub);
+        receiver_map, strict_mode, generic_stub);
     Code* cached_stub;
-    if (!maybe_cached_stub->To(&cached_stub)) {
-      return maybe_cached_stub;
-    }
+    if (!maybe_cached_stub->To(&cached_stub)) return maybe_cached_stub;
     handler_ics.Add(cached_stub);
   }
-
-  Code* stub;
   // Build the MEGAMORPHIC stub.
-  maybe_stub = ConstructMegamorphicStub(&receiver_maps,
+  Code* stub;
+  maybe_stub = ConstructMegamorphicStub(&target_receiver_maps,
                                         &handler_ics,
                                         strict_mode);
   if (!maybe_stub->To(&stub)) return maybe_stub;
-
-  MaybeObject* maybe_update = receiver->UpdateMapCodeCache(
-      megamorphic_name,
-      stub);
+  MaybeObject* maybe_update = cache->Update(&target_receiver_maps, flags, stub);
   if (maybe_update->IsFailure()) return maybe_update;
   return stub;
 }

src/objects-debug.cc

@@ -289,6 +289,12 @@ void CodeCache::CodeCacheVerify() {
 }
 
 
+void PolymorphicCodeCache::PolymorphicCodeCacheVerify() {
+  VerifyHeapPointer(cache());
+  ASSERT(cache()->IsUndefined() || cache()->IsPolymorphicCodeCacheHashTable());
+}
+
+
 void FixedArray::FixedArrayVerify() {
   for (int i = 0; i < length(); i++) {
     Object* e = get(i);

src/objects-inl.h

@@ -688,6 +688,11 @@ bool Object::IsCodeCacheHashTable() {
 }
 
 
+bool Object::IsPolymorphicCodeCacheHashTable() {
+  return IsHashTable();
+}
+
+
 bool Object::IsMapCache() {
   return IsHashTable();
 }
@@ -1903,6 +1908,7 @@ CAST_ACCESSOR(JSFunctionResultCache)
 CAST_ACCESSOR(NormalizedMapCache)
 CAST_ACCESSOR(CompilationCacheTable)
 CAST_ACCESSOR(CodeCacheHashTable)
+CAST_ACCESSOR(PolymorphicCodeCacheHashTable)
 CAST_ACCESSOR(MapCache)
 CAST_ACCESSOR(String)
 CAST_ACCESSOR(SeqString)
@@ -3338,6 +3344,8 @@ void SharedFunctionInfo::set_native(bool value) {
 ACCESSORS(CodeCache, default_cache, FixedArray, kDefaultCacheOffset)
 ACCESSORS(CodeCache, normal_type_cache, Object, kNormalTypeCacheOffset)
 
+ACCESSORS(PolymorphicCodeCache, cache, Object, kCacheOffset)
+
 bool Script::HasValidSource() {
   Object* src = this->source();
   if (!src->IsString()) return true;

src/objects-printer.cc

@@ -472,6 +472,13 @@ void CodeCache::CodeCachePrint(FILE* out) {
 }
 
 
+void PolymorphicCodeCache::PolymorphicCodeCachePrint(FILE* out) {
+  HeapObject::PrintHeader(out, "PolymorphicCodeCache");
+  PrintF(out, "\n - cache: ");
+  cache()->ShortPrint(out);
+}
+
+
 void FixedArray::FixedArrayPrint(FILE* out) {
   HeapObject::PrintHeader(out, "FixedArray");
   PrintF(out, " - length: %d", length());

src/objects.h

@@ -316,6 +316,7 @@ static const int kVariableSizeSentinel = 0;
   V(TYPE_SWITCH_INFO_TYPE)                                                     \
   V(SCRIPT_TYPE)                                                               \
   V(CODE_CACHE_TYPE)                                                           \
+  V(POLYMORPHIC_CODE_CACHE_TYPE)                                               \
                                                                                \
   V(FIXED_ARRAY_TYPE)                                                          \
   V(SHARED_FUNCTION_INFO_TYPE)                                                 \
@@ -427,7 +428,8 @@ static const int kVariableSizeSentinel = 0;
   V(SIGNATURE_INFO, SignatureInfo, signature_info)                             \
   V(TYPE_SWITCH_INFO, TypeSwitchInfo, type_switch_info)                        \
   V(SCRIPT, Script, script)                                                    \
-  V(CODE_CACHE, CodeCache, code_cache)
+  V(CODE_CACHE, CodeCache, code_cache)                                         \
+  V(POLYMORPHIC_CODE_CACHE, PolymorphicCodeCache, polymorphic_code_cache)
 
 #ifdef ENABLE_DEBUGGER_SUPPORT
 #define STRUCT_LIST_DEBUGGER(V)                                                \
@@ -544,6 +546,7 @@ enum InstanceType {
   TYPE_SWITCH_INFO_TYPE,
   SCRIPT_TYPE,
   CODE_CACHE_TYPE,
+  POLYMORPHIC_CODE_CACHE_TYPE,
   // The following two instance types are only used when ENABLE_DEBUGGER_SUPPORT
   // is defined. However as include/v8.h contain some of the instance type
   // constants always having them avoids them getting different numbers
@@ -752,6 +755,7 @@ class MaybeObject BASE_EMBEDDED {
   V(NormalizedMapCache)                        \
   V(CompilationCacheTable)                     \
   V(CodeCacheHashTable)                        \
+  V(PolymorphicCodeCacheHashTable)             \
   V(MapCache)                                  \
   V(Primitive)                                 \
   V(GlobalObject)                              \
@@ -2840,11 +2844,6 @@ class NormalizedMapCache: public FixedArray {
 #ifdef DEBUG
   void NormalizedMapCacheVerify();
 #endif
-
- private:
-  static int Hash(Map* fast);
-
-  static bool CheckHit(Map* slow, Map* fast, PropertyNormalizationMode mode);
 };
 
 
@@ -3964,6 +3963,21 @@ class Map: public HeapObject {
   // following back pointers.
   void ClearNonLiveTransitions(Heap* heap, Object* real_prototype);
 
+  // Computes a hash value for this map, to be used in HashTables and such.
+  int Hash();
+
+  // Compares this map to another to see if they describe equivalent objects.
+  // If |mode| is set to CLEAR_INOBJECT_PROPERTIES, |other| is treated as if
+  // it had exactly zero inobject properties.
+  // The "shared" flags of both this map and |other| are ignored.
+  bool EquivalentToForNormalization(Map* other, PropertyNormalizationMode mode);
+
+  // Returns true if this map and |other| describe equivalent objects.
+  // The "shared" flags of both this map and |other| are ignored.
+  bool EquivalentTo(Map* other) {
+    return EquivalentToForNormalization(other, KEEP_INOBJECT_PROPERTIES);
+  }
+
   // Dispatched behavior.
 #ifdef OBJECT_PRINT
   inline void MapPrint() {
@@ -5373,6 +5387,49 @@ class CodeCacheHashTable: public HashTable<CodeCacheHashTableShape,
 };
 
 
+class PolymorphicCodeCache: public Struct {
+ public:
+  DECL_ACCESSORS(cache, Object)
+
+  MUST_USE_RESULT MaybeObject* Update(MapList* maps,
+                                      Code::Flags flags,
+                                      Code* code);
+  Object* Lookup(MapList* maps, Code::Flags flags);
+
+  static inline PolymorphicCodeCache* cast(Object* obj);
+
+#ifdef OBJECT_PRINT
+  inline void PolymorphicCodeCachePrint() {
+    PolymorphicCodeCachePrint(stdout);
+  }
+  void PolymorphicCodeCachePrint(FILE* out);
+#endif
+#ifdef DEBUG
+  void PolymorphicCodeCacheVerify();
+#endif
+
+  static const int kCacheOffset = HeapObject::kHeaderSize;
+  static const int kSize = kCacheOffset + kPointerSize;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(PolymorphicCodeCache);
+};
+
+
+class PolymorphicCodeCacheHashTable
+    : public HashTable<CodeCacheHashTableShape, HashTableKey*> {
+ public:
+  Object* Lookup(MapList* maps, int code_kind);
+  MUST_USE_RESULT MaybeObject* Put(MapList* maps, int code_kind, Code* code);
+
+  static inline PolymorphicCodeCacheHashTable* cast(Object* obj);
+
+  static const int kInitialSize = 64;
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(PolymorphicCodeCacheHashTable);
+};
+
+
 enum AllowNullsFlag {ALLOW_NULLS, DISALLOW_NULLS};
 enum RobustnessFlag {ROBUST_STRING_TRAVERSAL, FAST_STRING_TRAVERSAL};