EVM-C: reorder and add create_address to evm_result

include/evm.h

@@ -77,30 +77,43 @@ struct evm_result {
     /// The value is valid only if evm_result::code == ::EVM_SUCCESS.
     int64_t gas_left;
 
-    /// The reference to output data. The memory containing the output data
-    /// is owned by EVM and is freed with evm_release_result_fn().
-    uint8_t const* output_data;
+    union
+    {
+        struct
+        {
+            /// The reference to output data. The memory containing the output
+            /// data is owned by EVM and is freed with evm_result::release().
+            uint8_t const* output_data;
+
+            /// The size of the output data.
+            size_t output_size;
+        };
+
+        /// The address of the successfully created contract.
+        ///
+        /// This field has valid value only if the evm_result comes from a
+        /// successful CREATE opcode execution
+        /// (i.e. evm_call_fn(..., EVM_CREATE, ...)).
+        struct evm_uint160be create_address;
+    };
 
-    /// The size of the output data.
-    size_t output_size;
+    /// The pointer to the result release implementation.
+    ///
+    /// This function pointer must be set by the VM implementation and works
+    /// similary to C++ virtual destructor. Attaching the releaser to the result
+    /// itself allows VM composition.
+    evm_release_result_fn release;
 
     /// @name Optional
     /// The optional information that EVM is not required to provide.
     /// @{
 
-    /// The pointer to EVM-owned memory. For EVM internal use.
-    /// @see output_data.
-    void* internal_memory;
-
     /// The error message explaining the result code.
     char const* error_message;
 
-    /// The pointer to the result release implementation.
-    ///
-    /// This function pointer must be set by the VM implementation and works
-    /// similary to C++ virtual destructor. Attaching the releaser to the result
-    /// itself allows VM composition.
-    evm_release_result_fn release;
+    /// The pointer to EVM-owned memory. For EVM internal use.
+    /// @see output_data.
+    void* internal_memory;
 
     /// @}
 };