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      1 // Copyright 2010 the V8 project authors. All rights reserved.
      2 // Redistribution and use in source and binary forms, with or without
      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above
      9 //       copyright notice, this list of conditions and the following
     10 //       disclaimer in the documentation and/or other materials provided
     11 //       with the distribution.
     12 //     * Neither the name of Google Inc. nor the names of its
     13 //       contributors may be used to endorse or promote products derived
     14 //       from this software without specific prior written permission.
     15 //
     16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 #ifndef V8_DATAFLOW_H_
     29 #define V8_DATAFLOW_H_
     30 
     31 #include "ast.h"
     32 #include "compiler.h"
     33 
     34 namespace v8 {
     35 namespace internal {
     36 
     37 // This class is used to number all expressions in the AST according to
     38 // their evaluation order (post-order left-to-right traversal).
     39 class AstLabeler: public AstVisitor {
     40  public:
     41   AstLabeler() : next_number_(0) {}
     42 
     43   void Label(CompilationInfo* info);
     44 
     45  private:
     46   CompilationInfo* info() { return info_; }
     47 
     48   void VisitDeclarations(ZoneList<Declaration*>* decls);
     49   void VisitStatements(ZoneList<Statement*>* stmts);
     50 
     51   // AST node visit functions.
     52 #define DECLARE_VISIT(type) virtual void Visit##type(type* node);
     53   AST_NODE_LIST(DECLARE_VISIT)
     54 #undef DECLARE_VISIT
     55 
     56   // Traversal number for labelling AST nodes.
     57   int next_number_;
     58 
     59   CompilationInfo* info_;
     60 
     61   DISALLOW_COPY_AND_ASSIGN(AstLabeler);
     62 };
     63 
     64 
     65 class VarUseMap : public HashMap {
     66  public:
     67   VarUseMap() : HashMap(VarMatch) {}
     68 
     69   ZoneList<Expression*>* Lookup(Variable* var);
     70 
     71  private:
     72   static bool VarMatch(void* key1, void* key2) { return key1 == key2; }
     73 };
     74 
     75 
     76 class DefinitionInfo : public ZoneObject {
     77  public:
     78   explicit DefinitionInfo() : last_use_(NULL) {}
     79 
     80   Expression* last_use() { return last_use_; }
     81   void set_last_use(Expression* expr) { last_use_ = expr; }
     82 
     83  private:
     84   Expression* last_use_;
     85   Register location_;
     86 };
     87 
     88 
     89 class LivenessAnalyzer : public AstVisitor {
     90  public:
     91   LivenessAnalyzer() {}
     92 
     93   void Analyze(FunctionLiteral* fun);
     94 
     95  private:
     96   void VisitStatements(ZoneList<Statement*>* stmts);
     97 
     98   void RecordUse(Variable* var, Expression* expr);
     99   void RecordDef(Variable* var, Expression* expr);
    100 
    101 
    102   // AST node visit functions.
    103 #define DECLARE_VISIT(type) virtual void Visit##type(type* node);
    104   AST_NODE_LIST(DECLARE_VISIT)
    105 #undef DECLARE_VISIT
    106 
    107   // Map for tracking the live variables.
    108   VarUseMap live_vars_;
    109 
    110   DISALLOW_COPY_AND_ASSIGN(LivenessAnalyzer);
    111 };
    112 
    113 
    114 } }  // namespace v8::internal
    115 
    116 
    117 #endif  // V8_DATAFLOW_H_
    118