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 to_basic_block_normal_form.cc
   *
   * \brief Turn an expression to the basic normal form.
   */
  #include <tvm/relay/analysis.h>
  #include <tvm/relay/expr_functor.h>
  #include <tvm/relay/transform.h>
  #include <tvm/runtime/logging.h>
  
  #include "../../support/arena.h"
  #include "../analysis/dependency_graph.h"
  #include "./pass_utils.h"
  
  namespace tvm {
  namespace relay {
  
  IRModule ToBasicBlockNormalForm(const IRModule& mod) {
    // Create a new module by shallow copy.
    IRModule new_mod = mod->ShallowCopy();
  
    tvm::Map<GlobalVar, Function> updates;
    auto funcs = new_mod->functions;
    for (const auto& it : funcs) {
      ICHECK_EQ(FreeVars(it.second).size(), 0) << "Expected no free variables";
      if (const auto* n = it.second.as<FunctionNode>()) {
        if (n->GetAttr<String>(attr::kCompiler).defined()) continue;
        Function func = GetRef<Function>(n);
        Function ret = Downcast<Function>(ToBasicBlockNormalFormAux(func));
        VLOG(1) << "rewritten:" << std::endl
                << PrettyPrint(func) << std::endl
                << "to BasicBlockANF:" << std::endl
                << PrettyPrint(ret);
        updates.Set(it.first, Downcast<Function>(ret));
      }
    }
  
    for (auto pair : updates) {
      new_mod->Add(pair.first, pair.second, true);
    }
  
    return new_mod;
  }
  
  bool BasicBlockNormalFormCheck(const Expr& e) {
    // calculate all the dependency between nodes.
    support::Arena arena;
    DependencyGraph dg = DependencyGraph::Create(&arena, e);
    std::pair<NodeScopeMap, ExprSet> scopes = CalcScope(dg);
    for (auto expr : scopes.second) {
      LOG(FATAL) << "The expression below violates the basic block normal form in that "
                 << "its scope should be lifted:\n"
                 << expr;
    }
    return scopes.second.size() == 0;
  }
  
  TVM_REGISTER_GLOBAL("relay.analysis.check_basic_block_normal_form")
      .set_body_typed(BasicBlockNormalFormCheck);
  
  namespace transform {
  
  Pass ToBasicBlockNormalForm() {
    runtime::TypedPackedFunc<IRModule(IRModule, PassContext)> pass_func =
        [=](IRModule m, PassContext pc) { return relay::ToBasicBlockNormalForm(m); };
    return CreateModulePass(pass_func, 1, "ToBasicBlockNormalForm", {});
  }
  
  TVM_REGISTER_GLOBAL("relay._transform.ToBasicBlockNormalForm")
      .set_body_typed(ToBasicBlockNormalForm);
  
  }  // namespace transform
  
  }  // namespace relay
  }  // namespace tvm
  