text: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  /*!
   * \file legalize.cc
   * \brief Converts an expr to another expr. This pass can be used to transform an op based on its
   * shape, dtype or layout to another op or a sequence of ops.
   */
  
  #include <tvm/operation.h>
  #include <tvm/relay/expr_functor.h>
  #include <tvm/relay/op_attr_types.h>
  #include <tvm/relay/transform.h>
  
  namespace tvm {
  namespace relay {
  
  namespace legalize {
  
  // Call registered FTVMLegalize of an op
  // Returns the legalized expression
  class Legalizer : public ExprMutator {
   public:
    explicit Legalizer(const std::string& legalize_map_attr_name)
        : legalize_map_attr_name_{legalize_map_attr_name} {}
  
    Expr VisitExpr_(const CallNode* call_node) {
      // Get the new_call node without any changes to current call node.
      Expr new_e = ExprMutator::VisitExpr_(call_node);
      Call new_call = Downcast<Call>(new_e);
  
      // Check if the string is registered in the OpRegistry.
      if (!Op::HasAttr(legalize_map_attr_name_)) {
        return new_e;
      }
  
      // Collect the registered legalize function.
      auto fop_legalize = Op::GetAttr<FTVMLegalize>(legalize_map_attr_name_);
      auto call_op = call_node->op;
      if (call_op.as<OpNode>()) {
        Op op = Downcast<Op>(call_node->op);
  
        if (fop_legalize.count(op)) {
          // Collect the new_args.
          tvm::Array<Expr> call_args = new_call->args;
  
          // Collect input and output dtypes to pass on to Legalize API.
          tvm::Array<tvm::relay::Type> types;
          for (auto arg : call_node->args) {
            types.push_back(arg->checked_type());
          }
          types.push_back(call_node->checked_type());
  
          // Transform the op by calling the registered legalize function.
          Expr legalized_value = fop_legalize[op](call_node->attrs, call_args, types);
  
          // Reassign new_e if the transformation succeeded.
          if (legalized_value.defined()) {
            // Check that the returned Expr from legalize is CallNode.
            const CallNode* legalized_call_node = legalized_value.as<CallNode>();
            CHECK(legalized_call_node)
                << "Can only replace the original operator with another call node";
  
            new_e = legalized_value;
          }
        }
      }
  
      return new_e;
    }
  
   private:
    std::string legalize_map_attr_name_;
  };
  
  Expr Legalize(const Expr& expr, const std::string& legalize_map_attr_name) {
    return Legalizer(legalize_map_attr_name).Mutate(expr);
  }
  
  }  // namespace legalize
  
  namespace transform {
  
  Pass Legalize(const std::string& legalize_map_attr_name) {
    runtime::TypedPackedFunc<Function(Function, Module, PassContext)> pass_func =
        [=](Function f, Module m, PassContext pc) {
          return Downcast<Function>(relay::legalize::Legalize(f, legalize_map_attr_name));
        };
    return CreateFunctionPass(pass_func, 1, "Legalize", {ir::StringImm::make("InferType")});
  }
  
  TVM_REGISTER_API("relay._transform.Legalize").set_body_typed(Legalize);
  
  }  // namespace transform
  
  }  // namespace relay
  }  // namespace tvm
  