src/hotspot/share/c1/c1_Instruction.cpp

*** 145,155 ****
    }
  
    return false;
  }
  
! bool Instruction::maybe_flattened_array() const {
    if (ValueArrayFlatten) {
      ciType* type = declared_type();
      if (type != NULL) {
        if (type->is_value_array_klass()) {
          ciValueKlass* element_klass = type->as_value_array_klass()->element_klass()->as_value_klass();
--- 145,155 ----
    }
  
    return false;
  }
  
! bool Instruction::maybe_flattened_array() {
    if (ValueArrayFlatten) {
      ciType* type = declared_type();
      if (type != NULL) {
        if (type->is_value_array_klass()) {
          ciValueKlass* element_klass = type->as_value_array_klass()->element_klass()->as_value_klass();
*** 165,174 ****
--- 165,178 ----
            //    (ValueType[] <: <any interface>[])
            // We will add a runtime check for flat-ness.
            return true;
          }
        }
+     } else if (as_Phi() != NULL) {
+       // Type info gets lost during Phi merging, but we might be storing into a
+       // flattened array, so we should do a runtime check.
+       return true;
      }
    }
  
    return false;
  }