Propagate reaching definitions to the instuctions of a block.

After computing RD_in for all flow graph nodes, push the reaching
definitions through the basic blocks to annotate all variable
references in the AST.

Review URL: http://codereview.chromium.org/889003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4143 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/ast.cc

@@ -78,14 +78,16 @@ VariableProxy::VariableProxy(Handle<String> name,
     var_(NULL),
     is_this_(is_this),
     inside_with_(inside_with),
-    is_trivial_(false) {
+    is_trivial_(false),
+    reaching_definitions_(NULL) {
   // names must be canonicalized for fast equality checks
   ASSERT(name->IsSymbol());
 }
 
 
 VariableProxy::VariableProxy(bool is_this)
-  : is_this_(is_this) {
+  : is_this_(is_this),
+    reaching_definitions_(NULL) {
 }
 
 

src/ast.h

@@ -103,6 +103,7 @@ namespace internal {
 class TargetCollector;
 class MaterializedLiteral;
 class DefinitionInfo;
+class BitVector;
 
 #define DEF_FORWARD_DECLARATION(type) class type;
 AST_NODE_LIST(DEF_FORWARD_DECLARATION)
@@ -1041,6 +1042,9 @@ class VariableProxy: public Expression {
   bool is_trivial() { return is_trivial_; }
   void set_is_trivial(bool b) { is_trivial_ = b; }
 
+  BitVector* reaching_definitions() { return reaching_definitions_; }
+  void set_reaching_definitions(BitVector* rd) { reaching_definitions_ = rd; }
+
   // Bind this proxy to the variable var.
   void BindTo(Variable* var);
 
@@ -1050,6 +1054,7 @@ class VariableProxy: public Expression {
   bool is_this_;
   bool inside_with_;
   bool is_trivial_;
+  BitVector* reaching_definitions_;
 
   VariableProxy(Handle<String> name, bool is_this, bool inside_with);
   explicit VariableProxy(bool is_this);

src/data-flow.h

@@ -129,6 +129,10 @@ class BitVector: public ZoneObject {
 
   int length() const { return length_; }
 
+#ifdef DEBUG
+  void Print();
+#endif
+
  private:
   int length_;
   int data_length_;
@@ -235,6 +239,7 @@ class Node: public ZoneObject {
                                              bool mark);
   virtual void ComputeRDOut(BitVector* result) = 0;
   virtual void UpdateRDIn(WorkList<Node>* worklist, bool mark) = 0;
+  virtual void PropagateReachingDefinitions(List<BitVector*>* variables);
 
 #ifdef DEBUG
   void AssignNodeNumber();
@@ -324,6 +329,7 @@ class BlockNode: public Node {
                                      bool mark);
   void ComputeRDOut(BitVector* result);
   void UpdateRDIn(WorkList<Node>* worklist, bool mark);
+  void PropagateReachingDefinitions(List<BitVector*>* variables);
 
 #ifdef DEBUG
   void PrintText();