Fix missing type feedback check for Generic*String addition.

src/hydrogen.cc

 // Copyright 2013 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 8341 matching lines @@
                      Deoptimizer::SOFT);
     right_type = handle(Type::Any(), isolate());
   } else {
     if (!maybe_string_add) right = TruncateToNumber(right, &right_type);
     right_rep = Representation::FromType(right_type);
   }
 
   // Special case for string addition here.
   if (op == Token::ADD &&
       (left_type->Is(Type::String()) || right_type->Is(Type::String()))) {
+    // Validate type feedback for left argument.
     if (left_type->Is(Type::String())) {
       IfBuilder if_isstring(this);
       if_isstring.If<HIsStringAndBranch>(left);
       if_isstring.Then();
       if_isstring.ElseDeopt("Expected string for LHS of binary operation");
-    } else if (left_type->Is(Type::Number())) {
+    }
+
+    // Validate type feedback for right argument.
+    if (right_type->Is(Type::String())) {
+      IfBuilder if_isstring(this);
+      if_isstring.If<HIsStringAndBranch>(right);
+      if_isstring.Then();
+      if_isstring.ElseDeopt("Expected string for RHS of binary operation");
+    }
+
+    // Convert left argument as necessary.
+    if (left_type->Is(Type::Number())) {
+      ASSERT(right_type->Is(Type::String()));
       left = BuildNumberToString(left, left_type);
-    } else {
+    } else if (!left_type->Is(Type::String())) {
       ASSERT(right_type->Is(Type::String()));
       HValue* function = AddLoadJSBuiltin(Builtins::STRING_ADD_RIGHT);
       Add<HPushArgument>(left);
       Add<HPushArgument>(right);
       return NewUncasted<HInvokeFunction>(function, 2);
     }
 
-    if (right_type->Is(Type::String())) {
-      IfBuilder if_isstring(this);
-      if_isstring.If<HIsStringAndBranch>(right);
-      if_isstring.Then();
-      if_isstring.ElseDeopt("Expected string for RHS of binary operation");
-    } else if (right_type->Is(Type::Number())) {
+    // Convert right argument as necessary.
+    if (right_type->Is(Type::Number())) {
+      ASSERT(left_type->Is(Type::String()));
       right = BuildNumberToString(right, right_type);
-    } else {
+    } else if (!right_type->Is(Type::String())) {
       ASSERT(left_type->Is(Type::String()));
       HValue* function = AddLoadJSBuiltin(Builtins::STRING_ADD_LEFT);
       Add<HPushArgument>(left);
       Add<HPushArgument>(right);
       return NewUncasted<HInvokeFunction>(function, 2);
     }
 
     return NewUncasted<HStringAdd>(left, right, STRING_ADD_CHECK_NONE);
   }
 
@@ skipping 1937 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal