Add MEGAMORPHIC state support for KeyedLoadIC

src/ic/ic.cc

Index: src/ic/ic.cc
diff --git a/src/ic/ic.cc b/src/ic/ic.cc
index e6b691b9265664a4c28956cdf65481390e465779..62f055af578041fcd0271ab13831e77c57f2b325 100644
--- a/src/ic/ic.cc
+++ b/src/ic/ic.cc
@@ -606,11 +606,12 @@ void CompareIC::Clear(Isolate* isolate, Address address, Code* target,
 
 
 // static
-Handle<Code> KeyedLoadIC::generic_stub(Isolate* isolate) {
+Handle<Code> KeyedLoadIC::megamorphic_stub(Isolate* isolate) {
   if (FLAG_compiled_keyed_generic_loads) {
+    // TODO(dcarney): what do to here?

[Jakob Kummerow, 2015/01/29 15:58:55]

Put in a TODO comment into the hydrogen-generated stub that explains that it
needs to be updated not to use the KeyedLookupCache any more. And I'd suggest to
also add an UNREACHABLE right next to the comment to make sure it isn't
overlooked when someone tries to turn on the flag.

Medium term, the generated stub should be beefed up to the point where it can
replace the handwritten one, but that's not at the top of our to-do list
currently.

     return KeyedLoadGenericStub(isolate).GetCode();
   } else {
-    return isolate->builtins()->KeyedLoadIC_Generic();
+    return isolate->builtins()->KeyedLoadIC_Megamorphic();
   }
 }
 
@@ -706,7 +707,7 @@ MaybeHandle<Object> LoadIC::Load(Handle<Object> object, Handle<Name> name) {
       if (UseVector()) {
         ConfigureVectorState(GENERIC);
       } else {
-        set_target(*KeyedLoadIC::generic_stub(isolate()));
+        set_target(*KeyedLoadIC::megamorphic_stub(isolate()));
       }
       TRACE_IC("LoadIC", name);
       TRACE_GENERIC_IC(isolate(), "LoadIC", "name as array index");
@@ -972,9 +973,7 @@ void IC::PatchCache(Handle<Name> name, Handle<Code> code) {
       UNREACHABLE();
       break;
     case GENERIC:

[Jakob Kummerow, 2015/01/29 15:58:55]

nit: just combine it with the DEFAULT case.

-      // The generic keyed store stub re-uses store handlers, which can miss.
-      // That's ok, no reason to do anything.
-      DCHECK(target()->kind() == Code::KEYED_STORE_IC);
+      UNREACHABLE();
       break;
   }
 }
@@ -1022,7 +1021,7 @@ Handle<Code> LoadIC::megamorphic_stub() {
     return stub.GetCode();
   } else {
     DCHECK_EQ(Code::KEYED_LOAD_IC, kind());
-    return KeyedLoadIC::generic_stub(isolate());
+    return KeyedLoadIC::megamorphic_stub(isolate());
   }
 }
 
@@ -1091,8 +1090,6 @@ void LoadIC::UpdateCaches(LookupIterator* lookup) {
 
 
 void IC::UpdateMegamorphicCache(HeapType* type, Name* name, Code* code) {
-  // Megamorphic state isn't implemented for keyed loads currently.
-  if (kind() == Code::KEYED_LOAD_IC) return;
   Map* map = *TypeToMap(type, isolate());
   isolate()->stub_cache()->Set(name, map, code);
 }
@@ -1370,14 +1367,14 @@ Handle<Code> KeyedLoadIC::LoadElementStub(Handle<HeapObject> receiver) {
     // If the miss wasn't due to an unseen map, a polymorphic stub
     // won't help, use the generic stub.
     TRACE_GENERIC_IC(isolate(), "KeyedLoadIC", "same map added twice");
-    return generic_stub();
+    return megamorphic_stub(isolate());
   }
 
   // If the maximum number of receiver maps has been exceeded, use the generic
   // version of the IC.
   if (target_receiver_maps.length() > kMaxKeyedPolymorphism) {
     TRACE_GENERIC_IC(isolate(), "KeyedLoadIC", "max polymorph exceeded");
-    return generic_stub();
+    return megamorphic_stub(isolate());
   }
 
   if (FLAG_vector_ics) {
@@ -1407,7 +1404,7 @@ MaybeHandle<Object> KeyedLoadIC::Load(Handle<Object> object,
   }
 
   Handle<Object> load_handle;
-  Handle<Code> stub = generic_stub();
+  Handle<Code> stub = megamorphic_stub(isolate());
 
   // Check for non-string values that can be converted into an
   // internalized string directly or is representable as a smi.
@@ -1428,7 +1425,7 @@ MaybeHandle<Object> KeyedLoadIC::Load(Handle<Object> object,
 
   if (!UseVector()) {
     if (!is_target_set()) {
-      Code* generic = *generic_stub();
+      Code* generic = *megamorphic_stub(isolate());
       if (*stub == generic) {
         TRACE_GENERIC_IC(isolate(), "KeyedLoadIC", "set generic");
       }
@@ -1438,7 +1435,7 @@ MaybeHandle<Object> KeyedLoadIC::Load(Handle<Object> object,
     }
   } else {
     if (!is_vector_set() || stub.is_null()) {
-      Code* generic = *generic_stub();
+      Code* generic = *megamorphic_stub(isolate());
       if (!stub.is_null() && *stub == generic) {
         ConfigureVectorState(GENERIC);

[Jakob Kummerow, 2015/01/29 15:58:55]

In a follow-up CL, please port the renaming changes to vector based ICs. That
should be a simple renaming, and it should not hurt to postpone it for now.

         TRACE_GENERIC_IC(isolate(), "KeyedLoadIC", "set generic");