VectorICs: megamorphic keyed loads in crankshaft don't need a vector.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 0ea1bd59bd42890451fd6de40e34dbe43335e9c9..e15e40e534f07c4cef6ab04ec75f6d1aef8a2be8 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -5407,11 +5407,8 @@ void HOptimizedGraphBuilder::VisitVariableProxy(VariableProxy* expr) {
                                     variable->name(),
                                     ast_context()->is_for_typeof());
         if (FLAG_vector_ics) {
-          Handle<SharedFunctionInfo> current_shared =
-              function_state()->compilation_info()->shared_info();
-          instr->SetVectorAndSlot(
-              handle(current_shared->feedback_vector(), isolate()),
-              expr->VariableFeedbackSlot());
+          instr->SetVectorAndSlot(handle(current_feedback_vector(), isolate()),
+                                  expr->VariableFeedbackSlot());
         }
         return ast_context()->ReturnInstruction(instr, expr->id());
       }
@@ -6902,10 +6899,8 @@ HInstruction* HOptimizedGraphBuilder::BuildNamedGeneric(
     HLoadNamedGeneric* result =
         New<HLoadNamedGeneric>(object, name, PREMONOMORPHIC);
     if (FLAG_vector_ics) {
-      Handle<SharedFunctionInfo> current_shared =
-          function_state()->compilation_info()->shared_info();
       Handle<TypeFeedbackVector> vector =
-          handle(current_shared->feedback_vector(), isolate());
+          handle(current_feedback_vector(), isolate());
       FeedbackVectorICSlot slot = expr->AsProperty()->PropertyFeedbackSlot();
       result->SetVectorAndSlot(vector, slot);
     }
@@ -6925,13 +6920,17 @@ HInstruction* HOptimizedGraphBuilder::BuildKeyedGeneric(
     HValue* key,
     HValue* value) {
   if (access_type == LOAD) {
+    InlineCacheState initial_state =
+        FLAG_vector_ics ? expr->AsProperty()->GetInlineCacheState()
+                        : PREMONOMORPHIC;
     HLoadKeyedGeneric* result =
-        New<HLoadKeyedGeneric>(object, key, PREMONOMORPHIC);
-    if (FLAG_vector_ics) {
-      Handle<SharedFunctionInfo> current_shared =
-          function_state()->compilation_info()->shared_info();
+        New<HLoadKeyedGeneric>(object, key, initial_state);
+    // HLoadKeyedGeneric with vector ics benefits from being encoded as
+    // MEGAMORPHIC because the vector/slot combo becomes unnecessary.
+    if (initial_state != MEGAMORPHIC) {
+      // We need to pass vector information.
       Handle<TypeFeedbackVector> vector =
-          handle(current_shared->feedback_vector(), isolate());
+          handle(current_feedback_vector(), isolate());
       FeedbackVectorICSlot slot = expr->AsProperty()->PropertyFeedbackSlot();
       result->SetVectorAndSlot(vector, slot);
     }
@@ -9316,10 +9315,8 @@ void HOptimizedGraphBuilder::VisitCall(Call* expr) {
           expr->IsUsingCallFeedbackICSlot(isolate())) {
         // We've never seen this call before, so let's have Crankshaft learn
         // through the type vector.
-        Handle<SharedFunctionInfo> current_shared =
-            function_state()->compilation_info()->shared_info();
         Handle<TypeFeedbackVector> vector =
-            handle(current_shared->feedback_vector(), isolate());
+            handle(current_feedback_vector(), isolate());
         FeedbackVectorICSlot slot = expr->CallFeedbackICSlot();
         call_function->SetVectorAndSlot(vector, slot);
       }