text: /*
   * Copyright 2004-2016 Cray Inc.
   * Other additional copyright holders may be indicated within.
   *
   * The entirety of this work is licensed 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.
   */
  
  #ifndef _EXPR_ANALYSIS_H_
  #define _EXPR_ANALYSIS_H_
  
  #include "expr.h"
  #include "symbol.h"
  
  
  /*
   * This class contains necessary data structures and member functions
   * for expression analysis. At this point it is only used in
   * denormalize pass and functionality is rather simple.
   *
   * Its main use in the pass is to decide if expressions are movable
   * during denormalization. 
   *
   * For now, this is a very conservative analysis. A more precise
   * analysis could distinguish between reads and writes to memory and
   * to take into account alias analysis.
   *
   * Overall an expression is "unsafe" if:
   *
   * - It is an unsafe primitive(check implementation for a list)
   * - It is a function CallExpr where FnSymbol:
   *   - Has ref arguments(const ref should be fine but not implemented)
   *   - Touches any globals
   *   - Touches any externs
   *   - Has unsafe primitives
   *
   * Function safety check is recursive
   */
  class SafeExprAnalysis {
  
    private:
      std::map<Expr*,bool> safeExprCache;
      std::map<FnSymbol*,bool> safeFnCache;
      std::map<FnSymbol*,bool> globalManipFuncCache;
      std::map<FnSymbol*,bool> externManipFuncCache;
    public:
      bool isNonEssentialPrimitive(CallExpr* ce);
  
      bool exprHasNoSideEffects(Expr* e, Expr* exprToMove);
      bool fnHasNoSideEffects(FnSymbol* fn);
  
      bool isSafePrimitive(CallExpr* ce);
  
      bool isRegisteredGlobalManip(FnSymbol* fn);
      bool getGlobalManip(FnSymbol* fn);
      void registerGlobalManip(FnSymbol* fn, bool manip);
  
      bool isRegisteredExternManip(FnSymbol* fn);
      bool getExternManip(FnSymbol* fn);
      void registerExternManip(FnSymbol* fn, bool manip);
  };
  
  #endif
  