[hydrogen] optimize switch with string clauses

src/ast.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 674 matching lines @@
     receiver_types_.Reserve(kMaxKeyedPolymorphism);
     oracle->CollectKeyedReceiverTypes(this->id(), &receiver_types_);
   }
 }
 
 
 void CaseClause::RecordTypeFeedback(TypeFeedbackOracle* oracle) {
   TypeInfo info = oracle->SwitchType(this);
   if (info.IsSmi()) {
     compare_type_ = SMI_ONLY;
+  } else if (info.IsSymbol()) {
+    compare_type_ = SYMBOL_ONLY;
   } else if (info.IsNonPrimitive()) {
     compare_type_ = OBJECT_ONLY;
   } else {
     ASSERT(compare_type_ == NONE);
   }
 }
 
 
 static bool CanCallWithoutIC(Handle<JSFunction> target, int arity) {
   SharedFunctionInfo* info = target->shared();
@@ skipping 483 matching lines @@
                        int pos)
     : label_(label),
       statements_(statements),
       position_(pos),
       compare_type_(NONE),
       compare_id_(AstNode::GetNextId(isolate)),
       entry_id_(AstNode::GetNextId(isolate)) {
 }
 
 } }  // namespace v8::internal