[ic] Remove disabled --collect-megamorphic-maps-from-stub-cache option.

... and stop checking that the native contexts of maps recorded in feedback vector
match function's native context - the feedback vector machinery already guarantees
that.

BUG=v8:6325

Change-Id: Iacd3f3a5f703694ff57b774b9658e186ad66641b
Reviewed-on: https://chromium-review.googlesource.com/490084Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44982}

src/feedback-vector.h

@@ -483,9 +483,6 @@ class FeedbackNexus {
     return NULL;
   }
 
-  // TODO(mvstanton): remove FindAllMaps, it didn't survive a code review.
-  void FindAllMaps(MapHandleList* maps) const { ExtractMaps(maps); }
-
   virtual InlineCacheState StateFromFeedback() const = 0;
   virtual int ExtractMaps(MapHandleList* maps) const;
   virtual MaybeHandle<Object> FindHandlerForMap(Handle<Map> map) const;

src/flag-definitions.h

@@ -363,8 +363,6 @@ DEFINE_INT(max_inlined_nodes_cumulative, 400,
            "maximum cumulative number of AST nodes considered for inlining")
 DEFINE_BOOL(loop_invariant_code_motion, true, "loop invariant code motion")
 DEFINE_BOOL(fast_math, true, "faster (but maybe less accurate) math functions")
-DEFINE_BOOL(collect_megamorphic_maps_from_stub_cache, false,
-            "crankshaft harvests type feedback from stub cache")
 DEFINE_BOOL(hydrogen_stats, false, "print statistics for hydrogen")
 DEFINE_BOOL(trace_check_elimination, false, "trace check elimination phase")
 DEFINE_BOOL(trace_environment_liveness, false,

src/ic/stub-cache.cc

@@ -111,43 +111,5 @@ void StubCache::Clear() {
   }
 }
 
-
-void StubCache::CollectMatchingMaps(SmallMapList* types, Handle<Name> name,
-                                    Handle<Context> native_context,
-                                    Zone* zone) {
-  for (int i = 0; i < kPrimaryTableSize; i++) {
-    if (primary_[i].key == *name) {
-      Map* map = primary_[i].map;
-      // Map can be nullptr, if the stub is constant function call
-      // with a primitive receiver.
-      if (map == nullptr) continue;
-
-      int offset = PrimaryOffset(*name, map);
-      if (entry(primary_, offset) == &primary_[i] &&
-          TypeFeedbackOracle::IsRelevantFeedback(map, *native_context)) {
-        types->AddMapIfMissing(Handle<Map>(map), zone);
-      }
-    }
-  }
-
-  for (int i = 0; i < kSecondaryTableSize; i++) {
-    if (secondary_[i].key == *name) {
-      Map* map = secondary_[i].map;
-      // Map can be nullptr, if the stub is constant function call
-      // with a primitive receiver.
-      if (map == nullptr) continue;
-
-      // Lookup in primary table and skip duplicates.
-      int primary_offset = PrimaryOffset(*name, map);
-
-      // Lookup in secondary table and add matches.
-      int offset = SecondaryOffset(*name, primary_offset);
-      if (entry(secondary_, offset) == &secondary_[i] &&
-          TypeFeedbackOracle::IsRelevantFeedback(map, *native_context)) {
-        types->AddMapIfMissing(Handle<Map>(map), zone);
-      }
-    }
-  }
-}
 }  // namespace internal
 }  // namespace v8

src/ic/stub-cache.h

@@ -45,9 +45,6 @@ class StubCache {
   Object* Get(Name* name, Map* map);
   // Clear the lookup table (@ mark compact collection).
   void Clear();
-  // Collect all maps that match the name.
-  void CollectMatchingMaps(SmallMapList* types, Handle<Name> name,
-                           Handle<Context> native_context, Zone* zone);
 
   enum Table { kPrimary, kSecondary };
 

src/type-info.cc

@@ -388,8 +388,7 @@ void TypeFeedbackOracle::PropertyReceiverTypes(FeedbackSlot slot,
   receiver_types->Clear();
   if (!slot.IsInvalid()) {
     LoadICNexus nexus(feedback_vector_, slot);
-    CollectReceiverTypes(isolate()->load_stub_cache(), &nexus, name,
-                         receiver_types);
+    CollectReceiverTypes(&nexus, receiver_types);
   }
 }
 
@@ -412,8 +411,8 @@ void TypeFeedbackOracle::AssignmentReceiverTypes(FeedbackSlot slot,
                                                  Handle<Name> name,
                                                  SmallMapList* receiver_types) {
   receiver_types->Clear();
-  CollectReceiverTypes(isolate()->store_stub_cache(), slot, name,
-                       receiver_types);
+  StoreICNexus nexus(feedback_vector_, slot);
+  CollectReceiverTypes(&nexus, receiver_types);
 }
 
 void TypeFeedbackOracle::KeyedAssignmentReceiverTypes(
@@ -430,27 +429,6 @@ void TypeFeedbackOracle::CountReceiverTypes(FeedbackSlot slot,
   if (!slot.IsInvalid()) CollectReceiverTypes(slot, receiver_types);
 }
 
-void TypeFeedbackOracle::CollectReceiverTypes(StubCache* stub_cache,
-                                              FeedbackSlot slot,
-                                              Handle<Name> name,
-                                              SmallMapList* types) {
-  StoreICNexus nexus(feedback_vector_, slot);
-  CollectReceiverTypes(stub_cache, &nexus, name, types);
-}
-
-void TypeFeedbackOracle::CollectReceiverTypes(StubCache* stub_cache,
-                                              FeedbackNexus* nexus,
-                                              Handle<Name> name,
-                                              SmallMapList* types) {
-  if (FLAG_collect_megamorphic_maps_from_stub_cache &&
-      nexus->ic_state() == MEGAMORPHIC) {
-    types->Reserve(4, zone());
-    stub_cache->CollectMatchingMaps(types, name, native_context_, zone());
-  } else {
-    CollectReceiverTypes(nexus, types);
-  }
-}
-
 void TypeFeedbackOracle::CollectReceiverTypes(FeedbackSlot slot,
                                               SmallMapList* types) {
   FeedbackSlotKind kind = feedback_vector_->GetKind(slot);
@@ -468,20 +446,13 @@ void TypeFeedbackOracle::CollectReceiverTypes(FeedbackSlot slot,
 void TypeFeedbackOracle::CollectReceiverTypes(FeedbackNexus* nexus,
                                               SmallMapList* types) {
   MapHandleList maps;
-  if (nexus->ic_state() == MONOMORPHIC) {
-    Map* map = nexus->FindFirstMap();
-    if (map != NULL) maps.Add(handle(map));
-  } else if (nexus->ic_state() == POLYMORPHIC) {
-    nexus->FindAllMaps(&maps);
-  } else {
+  if (nexus->ExtractMaps(&maps) == 0) {
     return;
   }
+
   types->Reserve(maps.length(), zone());
   for (int i = 0; i < maps.length(); i++) {
-    Handle<Map> map(maps.at(i));
-    if (IsRelevantFeedback(*map, *native_context_)) {
-      types->AddMapIfMissing(maps.at(i), zone());
-    }
+    types->AddMapIfMissing(maps.at(i), zone());
   }
 }
 

src/type-info.h

@@ -58,13 +58,6 @@ class TypeFeedbackOracle: public ZoneObject {
   void CollectReceiverTypes(FeedbackSlot slot, SmallMapList* types);
   void CollectReceiverTypes(FeedbackNexus* nexus, SmallMapList* types);
 
-  static bool IsRelevantFeedback(Map* map, Context* native_context) {
-    Object* constructor = map->GetConstructor();
-    return !constructor->IsJSFunction() ||
-           JSFunction::cast(constructor)->context()->native_context() ==
-               native_context;
-  }
-
   Handle<JSFunction> GetCallTarget(FeedbackSlot slot);
   Handle<AllocationSite> GetCallAllocationSite(FeedbackSlot slot);
   Handle<JSFunction> GetCallNewTarget(FeedbackSlot slot);
@@ -91,11 +84,6 @@ class TypeFeedbackOracle: public ZoneObject {
   Isolate* isolate() const { return isolate_; }
 
  private:
-  void CollectReceiverTypes(StubCache* stub_cache, FeedbackSlot slot,
-                            Handle<Name> name, SmallMapList* types);
-  void CollectReceiverTypes(StubCache* stub_cache, FeedbackNexus* nexus,
-                            Handle<Name> name, SmallMapList* types);
-
   // Returns true if there is at least one string map and if
   // all maps are string maps.
   bool HasOnlyStringMaps(SmallMapList* receiver_types);

test/cctest/test-feedback-vector.cc

@@ -350,7 +350,7 @@ TEST(VectorLoadICStates) {
   CompileRun("f({ blarg: 3, torino: 10, foo: 2 })");
   CHECK_EQ(POLYMORPHIC, nexus.StateFromFeedback());
   MapHandleList maps;
-  nexus.FindAllMaps(&maps);
+  nexus.ExtractMaps(&maps);
   CHECK_EQ(4, maps.length());
 
   // Finally driven megamorphic.
@@ -429,7 +429,7 @@ TEST(VectorLoadICOnSmi) {
   CHECK_EQ(POLYMORPHIC, nexus.StateFromFeedback());
 
   MapHandleList maps;
-  nexus.FindAllMaps(&maps);
+  nexus.ExtractMaps(&maps);
   CHECK_EQ(2, maps.length());
 
   // One of the maps should be the o map.
@@ -452,7 +452,7 @@ TEST(VectorLoadICOnSmi) {
   CompileRun("f(100)");
   CHECK_EQ(POLYMORPHIC, nexus.StateFromFeedback());
   MapHandleList maps2;
-  nexus.FindAllMaps(&maps2);
+  nexus.ExtractMaps(&maps2);
   CHECK_EQ(2, maps2.length());
 }