Add output alias function

src/include/migraph/operation.hpp

@@ -43,6 +43,9 @@ struct operation
      * the same the `output` shape.
      */
     argument compute(context& ctx, const shape& output, const std::vector<argument>& input) const;
+    /// An optional method to return which argument the output will alias. If
+    /// there is no aliased output then -1 can be returned.
+    int output_alias(const std::vector<shape>& input) const;
     /// An optional stream operator to print the operation. When this is not
     /// implemented, it will just print the operation's name.
     friend std::ostream& operator<<(std::ostream& os, const operation& op);
@@ -108,12 +111,32 @@ compute_op(const T& x, context& ctx, const shape& output_shape, const std::vecto
     return compute_op(rank<1>{}, x, ctx, output_shape, input);
 }
 
+template <class T>
+int output_alias_op(rank<0>, const T&, const std::vector<shape>&)
+{
+    return -1;
+}
+
+template <class T>
+auto output_alias_op(rank<1>, const T& x, const std::vector<shape>& shapes)
+    -> decltype(x.output_alias(shapes))
+{
+    return x.output_alias(shapes);
+}
+
+template <class T>
+int output_alias_op(const T& x, const std::vector<shape>& shapes)
+{
+    return output_alias_op(rank<1>{}, x, shapes);
+}
+
 /*
  * Type-erased interface for:
  *
  * struct operation
  * {
  *      std::string name() const;
+ *      int output_alias(const std::vector<shape>& input) const;
  *      shape compute_shape(const std::vector<shape>& input) const;
  *      argument compute(context& ctx,const shape& output,const std::vector<argument>& input) const;
  *     friend std::ostream & operator<<(std::ostream & os,const operation & op) ;
@@ -185,6 +208,12 @@ struct operation
         return (*this).private_detail_te_get_handle().name();
     }
 
+    int output_alias(const std::vector<shape>& input) const
+    {
+        assert((*this).private_detail_te_handle_mem_var);
+        return (*this).private_detail_te_get_handle().output_alias(input);
+    }
+
     shape compute_shape(const std::vector<shape>& input) const
     {
         assert((*this).private_detail_te_handle_mem_var);
@@ -217,6 +246,7 @@ struct operation
         virtual const std::type_info& type() const                                = 0;
 
         virtual std::string name() const                                   = 0;
+        virtual int output_alias(const std::vector<shape>& input) const    = 0;
         virtual shape compute_shape(const std::vector<shape>& input) const = 0;
         virtual argument
         compute(context& ctx, const shape& output, const std::vector<argument>& input) const = 0;
@@ -254,8 +284,15 @@ struct operation
 
         std::string name() const override { return private_detail_te_value.name(); }
 
+        int output_alias(const std::vector<shape>& input) const override
+        {
+
+            return output_alias_op(private_detail_te_value, input);
+        }
+
         shape compute_shape(const std::vector<shape>& input) const override
         {
+
             return private_detail_te_value.compute_shape(input);
         }
 

tools/include/operation.hpp

@@ -43,6 +43,9 @@ struct operation
      * the same the `output` shape.
      */
     argument compute(context& ctx, const shape& output, const std::vector<argument>& input) const;
+    /// An optional method to return which argument the output will alias. If
+    /// there is no aliased output then -1 can be returned.
+    int output_alias(const std::vector<shape>& input) const;
     /// An optional stream operator to print the operation. When this is not
     /// implemented, it will just print the operation's name.
     friend std::ostream& operator<<(std::ostream& os, const operation& op);
@@ -108,10 +111,30 @@ compute_op(const T& x, context& ctx, const shape& output_shape, const std::vecto
     return compute_op(rank<1>{}, x, ctx, output_shape, input);
 }
 
+
+template<class T>
+int output_alias_op(rank<0>, const T&, const std::vector<shape>&)
+{
+    return -1;
+}
+
+template<class T>
+auto output_alias_op(rank<1>, const T& x, const std::vector<shape>& shapes) -> decltype(x.output_alias(shapes))
+{
+    return x.output_alias(shapes);
+}
+
+template<class T>
+int output_alias_op(const T& x, const std::vector<shape>& shapes)
+{
+    return output_alias_op(rank<1>{}, x, shapes);
+}
+
 <%
  interface(
      'operation',
      virtual('name', returns = 'std::string', const = True),
+     virtual('output_alias', returns = 'int', input = 'const std::vector<shape>&', const = True, default = 'output_alias_op'),
      virtual('compute_shape', returns = 'shape', input = 'const std::vector<shape>&', const = True),
      virtual('compute',
              returns = 'argument',