src/tir/analysis/var_touch.cc

/*
 * 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 var_touch.cc
 * \brief Implementation of simple passes
 */
#include <tvm/tir/analysis.h>
#include <tvm/tir/stmt_functor.h>

namespace tvm {
namespace tir {

class VarTouchVisitor : public StmtExprVisitor {
 public:
  explicit VarTouchVisitor(std::function<bool(const VarNode*)> var_set)
      : var_set_(std::move(var_set)) {}

  void VisitStmt(const Stmt& stmt) final {
    if (use_var_) return;
    StmtExprVisitor::VisitStmt(stmt);
  }

  void VisitExpr(const PrimExpr& e) final {
    if (use_var_) return;
    StmtExprVisitor::VisitExpr(e);
  }

  void VisitExpr_(const VarNode* op) final { Handle(op); }

  void VisitStmt_(const BufferStoreNode* op) final {
    Handle(op->buffer->data.get());
    StmtVisitor::VisitStmt_(op);
  }

  void VisitExpr_(const BufferLoadNode* op) final {
    Handle(op->buffer->data.get());
    ExprVisitor::VisitExpr_(op);
  }

  void Handle(const VarNode* var) {
    if (var_set_(var)) use_var_ = true;
  }

  bool use_var_{false};

 private:
  std::function<bool(const VarNode*)> var_set_;
};

bool UsesVar(const Stmt& stmt, std::function<bool(const VarNode*)> var_set) {
  VarTouchVisitor visitor(std::move(var_set));
  visitor(stmt);
  return visitor.use_var_;
}

bool UsesVar(const PrimExpr& expr, std::function<bool(const VarNode*)> var_set) {
  VarTouchVisitor visitor(std::move(var_set));
  visitor(expr);
  return visitor.use_var_;
}

}  // namespace tir
}  // namespace tvm