Rework flow graph construction.

src/data-flow.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 10 matching lines @@
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "v8.h"
 
 #include "data-flow.h"
-#include "flow-graph.h"
 #include "scopes.h"
 
 namespace v8 {
 namespace internal {
 
 
 #ifdef DEBUG
 void BitVector::Print() {
   bool first = true;
   PrintF("{");
@@ skipping 572 matching lines @@
     CatchExtensionObject* expr) {
   ASSERT(av_.IsEmpty());
   Visit(expr->key());
   ProcessExpression(expr->value());
 }
 
 
 void AssignedVariablesAnalyzer::VisitAssignment(Assignment* expr) {
   ASSERT(av_.IsEmpty());
 
-  if (expr->target()->AsProperty() != NULL) {
-    // Visit receiver and key of property store and rhs.
-    Visit(expr->target()->AsProperty()->obj());
-    ProcessExpression(expr->target()->AsProperty()->key());
-    ProcessExpression(expr->value());
+  // There are three kinds of assignments: variable assignments, property
+  // assignments, and reference errors (invalid left-hand sides).
+  Variable* var = expr->target()->AsVariableProxy()->AsVariable();
+  Property* prop = expr->target()->AsProperty();
+  ASSERT(var == NULL || prop == NULL);
 
-    // If we have a variable as a receiver in a property store, check if
-    // we can mark it as trivial.
-    MarkIfTrivial(expr->target()->AsProperty()->obj());
+  if (var != NULL) {
+    MarkIfTrivial(expr->value());
+    Visit(expr->value());
+    if (expr->is_compound()) {
+      // Left-hand side occurs also as an rvalue.
+      MarkIfTrivial(expr->target());
+      ProcessExpression(expr->target());
+    }
+    RecordAssignedVar(var);
+
+  } else if (prop != NULL) {
+    MarkIfTrivial(expr->value());
+    Visit(expr->value());
+    if (!prop->key()->IsPropertyName()) {
+      MarkIfTrivial(prop->key());
+      ProcessExpression(prop->key());
+    }
+    MarkIfTrivial(prop->obj());
+    ProcessExpression(prop->obj());
+
   } else {
     Visit(expr->target());
-    ProcessExpression(expr->value());
-
-    Variable* var = expr->target()->AsVariableProxy()->AsVariable();
-    if (var != NULL) RecordAssignedVar(var);
   }
 }
 
 
 void AssignedVariablesAnalyzer::VisitThrow(Throw* expr) {
   ASSERT(av_.IsEmpty());
   Visit(expr->exception());
 }
 
 
 void AssignedVariablesAnalyzer::VisitProperty(Property* expr) {
   ASSERT(av_.IsEmpty());
-  Visit(expr->obj());
+  if (!expr->key()->IsPropertyName()) {
+    MarkIfTrivial(expr->key());
+    Visit(expr->key());
+  }
+  MarkIfTrivial(expr->obj());
   ProcessExpression(expr->key());

[fschneider, 2010/03/29 13:49:59]

That should be 

ProcessExpression(expr->obj());

[Kevin Millikin (Chromium), 2010/03/29 14:22:53]

Thank you.

-
-  // In case we have a variable as a receiver, check if we can mark
-  // it as trivial.
-  MarkIfTrivial(expr->obj());
 }
 
 
 void AssignedVariablesAnalyzer::VisitCall(Call* expr) {
   ASSERT(av_.IsEmpty());
   Visit(expr->expression());
   BitVector result(av_);
   for (int i = 0; i < expr->arguments()->length(); i++) {
     av_.Clear();
     Visit(expr->arguments()->at(i));
@@ skipping 39 matching lines @@
 
   Visit(expr->expression());
 
   Variable* var = expr->expression()->AsVariableProxy()->AsVariable();
   if (var != NULL) RecordAssignedVar(var);
 }
 
 
 void AssignedVariablesAnalyzer::VisitBinaryOperation(BinaryOperation* expr) {
   ASSERT(av_.IsEmpty());
-  Visit(expr->left());
-
-  ProcessExpression(expr->right());
-
-  // In case we have a variable on the left side, check if we can mark
-  // it as trivial.
+  MarkIfTrivial(expr->right());
+  Visit(expr->right());
   MarkIfTrivial(expr->left());
+  ProcessExpression(expr->left());
 }
 
 
 void AssignedVariablesAnalyzer::VisitCompareOperation(CompareOperation* expr) {
   ASSERT(av_.IsEmpty());
-  Visit(expr->left());
-
-  ProcessExpression(expr->right());
-
-  // In case we have a variable on the left side, check if we can mark
-  // it as trivial.
+  MarkIfTrivial(expr->right());
+  Visit(expr->right());
   MarkIfTrivial(expr->left());
+  ProcessExpression(expr->left());
 }
 
 
 void AssignedVariablesAnalyzer::VisitThisFunction(ThisFunction* expr) {
   // Nothing to do.
   ASSERT(av_.IsEmpty());
 }
 
 
 void AssignedVariablesAnalyzer::VisitDeclaration(Declaration* decl) {
   UNREACHABLE();
 }
 
 
-int ReachingDefinitions::IndexFor(Variable* var, int variable_count) {
-  // Parameters are numbered left-to-right from the beginning of the bit
-  // set.  Stack-allocated locals are allocated right-to-left from the end.
-  ASSERT(var != NULL && var->IsStackAllocated());
-  Slot* slot = var->slot();
-  if (slot->type() == Slot::PARAMETER) {
-    return slot->index();
-  } else {
-    return (variable_count - 1) - slot->index();
-  }
-}
-
-
-void Node::InitializeReachingDefinitions(int definition_count,
-                                         List<BitVector*>* variables,
-                                         WorkList<Node>* worklist,
-                                         bool mark) {
-  ASSERT(!IsMarkedWith(mark));
-  rd_.Initialize(definition_count);
-  MarkWith(mark);
-  worklist->Insert(this);
-}
-
-
-void BlockNode::InitializeReachingDefinitions(int definition_count,
-                                              List<BitVector*>* variables,
-                                              WorkList<Node>* worklist,
-                                              bool mark) {
-  ASSERT(!IsMarkedWith(mark));
-  int instruction_count = instructions_.length();
-  int variable_count = variables->length();
-
-  rd_.Initialize(definition_count);
-  // The RD_in set for the entry node has a definition for each parameter
-  // and local.
-  if (predecessor_ == NULL) {
-    for (int i = 0; i < variable_count; i++) rd_.rd_in()->Add(i);
-  }
-
-  for (int i = 0; i < instruction_count; i++) {
-    Expression* expr = instructions_[i]->AsExpression();
-    if (expr == NULL) continue;
-    Variable* var = expr->AssignedVariable();
-    if (var == NULL || !var->IsStackAllocated()) continue;
-
-    // All definitions of this variable are killed.
-    BitVector* def_set =
-        variables->at(ReachingDefinitions::IndexFor(var, variable_count));
-    rd_.kill()->Union(*def_set);
-
-    // All previously generated definitions are not generated.
-    rd_.gen()->Subtract(*def_set);
-
-    // This one is generated.
-    rd_.gen()->Add(expr->num());
-  }
-
-  // Add all blocks except the entry node to the worklist.
-  if (predecessor_ != NULL) {
-    MarkWith(mark);
-    worklist->Insert(this);
-  }
-}
-
-
-void ExitNode::ComputeRDOut(BitVector* result) {
-  // Should not be the predecessor of any node.
-  UNREACHABLE();
-}
-
-
-void BlockNode::ComputeRDOut(BitVector* result) {
-  // All definitions reaching this block ...
-  *result = *rd_.rd_in();
-  // ... except those killed by the block ...
-  result->Subtract(*rd_.kill());
-  // ... but including those generated by the block.
-  result->Union(*rd_.gen());
-}
-
-
-void BranchNode::ComputeRDOut(BitVector* result) {
-  // Branch nodes don't kill or generate definitions.
-  *result = *rd_.rd_in();
-}
-
-
-void JoinNode::ComputeRDOut(BitVector* result) {
-  // Join nodes don't kill or generate definitions.
-  *result = *rd_.rd_in();
-}
-
-
-void ExitNode::UpdateRDIn(WorkList<Node>* worklist, bool mark) {
-  // The exit node has no successors so we can just update in place.  New
-  // RD_in is the union over all predecessors.
-  int definition_count = rd_.rd_in()->length();
-  rd_.rd_in()->Clear();
-
-  BitVector temp(definition_count);
-  for (int i = 0, len = predecessors_.length(); i < len; i++) {
-    // Because ComputeRDOut always overwrites temp and its value is
-    // always read out before calling ComputeRDOut again, we do not
-    // have to clear it on each iteration of the loop.
-    predecessors_[i]->ComputeRDOut(&temp);
-    rd_.rd_in()->Union(temp);
-  }
-}
-
-
-void BlockNode::UpdateRDIn(WorkList<Node>* worklist, bool mark) {
-  // The entry block has no predecessor.  Its RD_in does not change.
-  if (predecessor_ == NULL) return;
-
-  BitVector new_rd_in(rd_.rd_in()->length());
-  predecessor_->ComputeRDOut(&new_rd_in);
-
-  if (rd_.rd_in()->Equals(new_rd_in)) return;
-
-  // Update RD_in.
-  *rd_.rd_in() = new_rd_in;
-  // Add the successor to the worklist if not already present.
-  if (!successor_->IsMarkedWith(mark)) {
-    successor_->MarkWith(mark);
-    worklist->Insert(successor_);
-  }
-}
-
-
-void BranchNode::UpdateRDIn(WorkList<Node>* worklist, bool mark) {
-  BitVector new_rd_in(rd_.rd_in()->length());
-  predecessor_->ComputeRDOut(&new_rd_in);
-
-  if (rd_.rd_in()->Equals(new_rd_in)) return;
-
-  // Update RD_in.
-  *rd_.rd_in() = new_rd_in;
-  // Add the successors to the worklist if not already present.
-  if (!successor0_->IsMarkedWith(mark)) {
-    successor0_->MarkWith(mark);
-    worklist->Insert(successor0_);
-  }
-  if (!successor1_->IsMarkedWith(mark)) {
-    successor1_->MarkWith(mark);
-    worklist->Insert(successor1_);
-  }
-}
-
-
-void JoinNode::UpdateRDIn(WorkList<Node>* worklist, bool mark) {
-  int definition_count = rd_.rd_in()->length();
-  BitVector new_rd_in(definition_count);
-
-  // New RD_in is the union over all predecessors.
-  BitVector temp(definition_count);
-  for (int i = 0, len = predecessors_.length(); i < len; i++) {
-    predecessors_[i]->ComputeRDOut(&temp);
-    new_rd_in.Union(temp);
-  }
-
-  if (rd_.rd_in()->Equals(new_rd_in)) return;
-
-  // Update RD_in.
-  *rd_.rd_in() = new_rd_in;
-  // Add the successor to the worklist if not already present.
-  if (!successor_->IsMarkedWith(mark)) {
-    successor_->MarkWith(mark);
-    worklist->Insert(successor_);
-  }
-}
-
-
-void Node::PropagateReachingDefinitions(List<BitVector*>* variables) {
-  // Nothing to do.
-}
-
-
-void BlockNode::PropagateReachingDefinitions(List<BitVector*>* variables) {
-  // Propagate RD_in from the start of the block to all the variable
-  // references.
-  int variable_count = variables->length();
-  BitVector rd = *rd_.rd_in();
-  for (int i = 0, len = instructions_.length(); i < len; i++) {
-    Expression* expr = instructions_[i]->AsExpression();
-    if (expr == NULL) continue;
-
-    // Look for a variable reference to record its reaching definitions.
-    VariableProxy* proxy = expr->AsVariableProxy();
-    if (proxy == NULL) {
-      // Not a VariableProxy?  Maybe it's a count operation.
-      CountOperation* count_operation = expr->AsCountOperation();
-      if (count_operation != NULL) {
-        proxy = count_operation->expression()->AsVariableProxy();
-      }
-    }
-    if (proxy == NULL) {
-      // OK, Maybe it's a compound assignment.
-      Assignment* assignment = expr->AsAssignment();
-      if (assignment != NULL && assignment->is_compound()) {
-        proxy = assignment->target()->AsVariableProxy();
-      }
-    }
-
-    if (proxy != NULL &&
-        proxy->var()->IsStackAllocated() &&
-        !proxy->var()->is_this()) {
-      // All definitions for this variable.
-      BitVector* definitions =
-          variables->at(ReachingDefinitions::IndexFor(proxy->var(),
-                                                      variable_count));
-      BitVector* reaching_definitions = new BitVector(*definitions);
-      // Intersected with all definitions (of any variable) reaching this
-      // instruction.
-      reaching_definitions->Intersect(rd);
-      proxy->set_reaching_definitions(reaching_definitions);
-    }
-
-    // It may instead (or also) be a definition.  If so update the running
-    // value of reaching definitions for the block.
-    Variable* var = expr->AssignedVariable();
-    if (var == NULL || !var->IsStackAllocated()) continue;
-
-    // All definitions of this variable are killed.
-    BitVector* def_set =
-        variables->at(ReachingDefinitions::IndexFor(var, variable_count));
-    rd.Subtract(*def_set);
-    // This definition is generated.
-    rd.Add(expr->num());
-  }
-}
-
-
-void ReachingDefinitions::Compute() {
-  // The definitions in the body plus an implicit definition for each
-  // variable at function entry.
-  int definition_count = body_definitions_->length() + variable_count_;
-  int node_count = postorder_->length();
-
-  // Step 1: For each stack-allocated variable, identify the set of all its
-  // definitions.
-  List<BitVector*> variables;
-  for (int i = 0; i < variable_count_; i++) {
-    // Add the initial definition for each variable.
-    BitVector* initial = new BitVector(definition_count);
-    initial->Add(i);
-    variables.Add(initial);
-  }
-  for (int i = 0, len = body_definitions_->length(); i < len; i++) {
-    // Account for each definition in the body as a definition of the
-    // defined variable.
-    Variable* var = body_definitions_->at(i)->AssignedVariable();
-    variables[IndexFor(var, variable_count_)]->Add(i + variable_count_);
-  }
-
-  // Step 2: Compute KILL and GEN for each block node, initialize RD_in for
-  // all nodes, and mark and add all nodes to the worklist in reverse
-  // postorder.  All nodes should currently have the same mark.
-  bool mark = postorder_->at(0)->IsMarkedWith(false);  // Negation of current.
-  WorkList<Node> worklist(node_count);
-  for (int i = node_count - 1; i >= 0; i--) {
-    postorder_->at(i)->InitializeReachingDefinitions(definition_count,
-                                                     &variables,
-                                                     &worklist,
-                                                     mark);
-  }
-
-  // Step 3: Until the worklist is empty, remove an item compute and update
-  // its rd_in based on its predecessor's rd_out.  If rd_in has changed, add
-  // all necessary successors to the worklist.
-  while (!worklist.is_empty()) {
-    Node* node = worklist.Remove();
-    node->MarkWith(!mark);
-    node->UpdateRDIn(&worklist, mark);
-  }
-
-  // Step 4: Based on RD_in for block nodes, propagate reaching definitions
-  // to all variable uses in the block.
-  for (int i = 0; i < node_count; i++) {
-    postorder_->at(i)->PropagateReachingDefinitions(&variables);
-  }
-}
-
-
-bool TypeAnalyzer::IsPrimitiveDef(int def_num) {
-  if (def_num < param_count_) return false;
-  if (def_num < variable_count_) return true;
-  return body_definitions_->at(def_num - variable_count_)->IsPrimitive();
-}
-
-
-void TypeAnalyzer::Compute() {
-  bool changed;
-  int count = 0;
-
-  do {
-    changed = false;
-
-    if (FLAG_print_graph_text) {
-      PrintF("TypeAnalyzer::Compute - iteration %d\n", count++);
-    }
-
-    for (int i = postorder_->length() - 1; i >= 0; --i) {
-      Node* node = postorder_->at(i);
-      if (node->IsBlockNode()) {
-        BlockNode* block = BlockNode::cast(node);
-        for (int j = 0; j < block->instructions()->length(); j++) {
-          Expression* expr = block->instructions()->at(j)->AsExpression();
-          if (expr != NULL) {
-            // For variable uses: Compute new type from reaching definitions.
-            VariableProxy* proxy = expr->AsVariableProxy();
-            if (proxy != NULL && proxy->reaching_definitions() != NULL) {
-              BitVector* rd = proxy->reaching_definitions();
-              bool prim_type = true;
-              // TODO(fsc): A sparse set representation of reaching
-              // definitions would speed up iterating here.
-              for (int k = 0; k < rd->length(); k++) {
-                if (rd->Contains(k) && !IsPrimitiveDef(k)) {
-                  prim_type = false;
-                  break;
-                }
-              }
-              // Reset changed flag if new type information was computed.
-              if (prim_type != proxy->IsPrimitive()) {
-                changed = true;
-                proxy->SetIsPrimitive(prim_type);
-              }
-            }
-          }
-        }
-      }
-    }
-  } while (changed);
-}
-
-
-void Node::MarkCriticalInstructions(
-    List<AstNode*>* stack,
-    ZoneList<Expression*>* body_definitions,
-    int variable_count) {
-}
-
-
-void BlockNode::MarkCriticalInstructions(
-    List<AstNode*>* stack,
-    ZoneList<Expression*>* body_definitions,
-    int variable_count) {
-  for (int i = instructions_.length() - 1; i >= 0; i--) {
-    // Only expressions can appear in the flow graph for now.
-    Expression* expr = instructions_[i]->AsExpression();
-    if (expr != NULL && !expr->is_live() &&
-        (expr->is_loop_condition() || expr->IsCritical())) {
-      expr->mark_as_live();
-      expr->ProcessNonLiveChildren(stack, body_definitions, variable_count);
-    }
-  }
-}
-
-
-void MarkLiveCode(ZoneList<Node*>* nodes,
-                  ZoneList<Expression*>* body_definitions,
-                  int variable_count) {
-  List<AstNode*> stack(20);
-
-  // Mark the critical AST nodes as live; mark their dependencies and
-  // add them to the marking stack.
-  for (int i = nodes->length() - 1; i >= 0; i--) {
-    nodes->at(i)->MarkCriticalInstructions(&stack, body_definitions,
-                                           variable_count);
-  }
-
-  // Continue marking dependencies until no more.
-  while (!stack.is_empty()) {
-  // Only expressions can appear in the flow graph for now.
-    Expression* expr = stack.RemoveLast()->AsExpression();
-    if (expr != NULL) {
-      expr->ProcessNonLiveChildren(&stack, body_definitions, variable_count);
-    }
-  }
-}
-
-
-#ifdef DEBUG
-
-// Print a textual representation of an instruction in a flow graph.  Using
-// the AstVisitor is overkill because there is no recursion here.  It is
-// only used for printing in debug mode.
-class TextInstructionPrinter: public AstVisitor {
- public:
-  TextInstructionPrinter() : number_(0) {}
-
-  int NextNumber() { return number_; }
-  void AssignNumber(AstNode* node) { node->set_num(number_++); }
-
- private:
-  // AST node visit functions.
-#define DECLARE_VISIT(type) virtual void Visit##type(type* node);
-  AST_NODE_LIST(DECLARE_VISIT)
-#undef DECLARE_VISIT
-
-  int number_;
-
-  DISALLOW_COPY_AND_ASSIGN(TextInstructionPrinter);
-};
-
-
-void TextInstructionPrinter::VisitDeclaration(Declaration* decl) {
-  UNREACHABLE();
-}
-
-
-void TextInstructionPrinter::VisitBlock(Block* stmt) {
-  PrintF("Block");
-}
-
-
-void TextInstructionPrinter::VisitExpressionStatement(
-    ExpressionStatement* stmt) {
-  PrintF("ExpressionStatement");
-}
-
-
-void TextInstructionPrinter::VisitEmptyStatement(EmptyStatement* stmt) {
-  PrintF("EmptyStatement");
-}
-
-
-void TextInstructionPrinter::VisitIfStatement(IfStatement* stmt) {
-  PrintF("IfStatement");
-}
-
-
-void TextInstructionPrinter::VisitContinueStatement(ContinueStatement* stmt) {
-  UNREACHABLE();
-}
-
-
-void TextInstructionPrinter::VisitBreakStatement(BreakStatement* stmt) {
-  UNREACHABLE();
-}
-
-
-void TextInstructionPrinter::VisitReturnStatement(ReturnStatement* stmt) {
-  PrintF("return @%d", stmt->expression()->num());
-}
-
-
-void TextInstructionPrinter::VisitWithEnterStatement(WithEnterStatement* stmt) {
-  PrintF("WithEnterStatement");
-}
-
-
-void TextInstructionPrinter::VisitWithExitStatement(WithExitStatement* stmt) {
-  PrintF("WithExitStatement");
-}
-
-
-void TextInstructionPrinter::VisitSwitchStatement(SwitchStatement* stmt) {
-  UNREACHABLE();
-}
-
-
-void TextInstructionPrinter::VisitDoWhileStatement(DoWhileStatement* stmt) {
-  PrintF("DoWhileStatement");
-}
-
-
-void TextInstructionPrinter::VisitWhileStatement(WhileStatement* stmt) {
-  PrintF("WhileStatement");
-}
-
-
-void TextInstructionPrinter::VisitForStatement(ForStatement* stmt) {
-  PrintF("ForStatement");
-}
-
-
-void TextInstructionPrinter::VisitForInStatement(ForInStatement* stmt) {
-  PrintF("ForInStatement");
-}
-
-
-void TextInstructionPrinter::VisitTryCatchStatement(TryCatchStatement* stmt) {
-  UNREACHABLE();
-}
-
-
-void TextInstructionPrinter::VisitTryFinallyStatement(
-    TryFinallyStatement* stmt) {
-  UNREACHABLE();
-}
-
-
-void TextInstructionPrinter::VisitDebuggerStatement(DebuggerStatement* stmt) {
-  PrintF("DebuggerStatement");
-}
-
-
-void TextInstructionPrinter::VisitFunctionLiteral(FunctionLiteral* expr) {
-  PrintF("FunctionLiteral");
-}
-
-
-void TextInstructionPrinter::VisitSharedFunctionInfoLiteral(
-    SharedFunctionInfoLiteral* expr) {
-  PrintF("SharedFunctionInfoLiteral");
-}
-
-
-void TextInstructionPrinter::VisitConditional(Conditional* expr) {
-  PrintF("Conditional");
-}
-
-
-void TextInstructionPrinter::VisitSlot(Slot* expr) {
-  UNREACHABLE();
-}
-
-
-void TextInstructionPrinter::VisitVariableProxy(VariableProxy* expr) {
-  Variable* var = expr->AsVariable();
-  if (var != NULL) {
-    PrintF("%s", *var->name()->ToCString());
-    if (var->IsStackAllocated() && expr->reaching_definitions() != NULL) {
-      expr->reaching_definitions()->Print();
-    }
-  } else {
-    ASSERT(expr->AsProperty() != NULL);
-    VisitProperty(expr->AsProperty());
-  }
-}
-
-
-void TextInstructionPrinter::VisitLiteral(Literal* expr) {
-  expr->handle()->ShortPrint();
-}
-
-
-void TextInstructionPrinter::VisitRegExpLiteral(RegExpLiteral* expr) {
-  PrintF("RegExpLiteral");
-}
-
-
-void TextInstructionPrinter::VisitObjectLiteral(ObjectLiteral* expr) {
-  PrintF("ObjectLiteral");
-}
-
-
-void TextInstructionPrinter::VisitArrayLiteral(ArrayLiteral* expr) {
-  PrintF("ArrayLiteral");
-}
-
-
-void TextInstructionPrinter::VisitCatchExtensionObject(
-    CatchExtensionObject* expr) {
-  PrintF("CatchExtensionObject");
-}
-
-
-void TextInstructionPrinter::VisitAssignment(Assignment* expr) {
-  Variable* var = expr->target()->AsVariableProxy()->AsVariable();
-  Property* prop = expr->target()->AsProperty();
-
-  if (var == NULL && prop == NULL) {
-    // Throw reference error.
-    Visit(expr->target());
-    return;
-  }
-
-  // Print the left-hand side.
-  if (var != NULL) {
-    PrintF("%s", *var->name()->ToCString());
-  } else if (prop != NULL) {
-    PrintF("@%d", prop->obj()->num());
-    if (prop->key()->IsPropertyName()) {
-      PrintF(".");
-      ASSERT(prop->key()->AsLiteral() != NULL);
-      prop->key()->AsLiteral()->handle()->Print();
-    } else {
-      PrintF("[@%d]", prop->key()->num());
-    }
-  }
-
-  // Print the operation.
-  if (expr->is_compound()) {
-    PrintF(" = ");
-    // Print the left-hand side again when compound.
-    if (var != NULL) {
-      PrintF("@%d", expr->target()->num());
-    } else {
-      PrintF("@%d", prop->obj()->num());
-      if (prop->key()->IsPropertyName()) {
-        PrintF(".");
-        ASSERT(prop->key()->AsLiteral() != NULL);
-        prop->key()->AsLiteral()->handle()->Print();
-      } else {
-        PrintF("[@%d]", prop->key()->num());
-      }
-    }
-    // Print the corresponding binary operator.
-    PrintF(" %s ", Token::String(expr->binary_op()));
-  } else {
-    PrintF(" %s ", Token::String(expr->op()));
-  }
-
-  // Print the right-hand side.
-  PrintF("@%d", expr->value()->num());
-
-  if (expr->num() != AstNode::kNoNumber) {
-    PrintF(" ;; D%d", expr->num());
-  }
-}
-
-
-void TextInstructionPrinter::VisitThrow(Throw* expr) {
-  PrintF("throw @%d", expr->exception()->num());
-}
-
-
-void TextInstructionPrinter::VisitProperty(Property* expr) {
-  if (expr->key()->IsPropertyName()) {
-    PrintF("@%d.", expr->obj()->num());
-    ASSERT(expr->key()->AsLiteral() != NULL);
-    expr->key()->AsLiteral()->handle()->Print();
-  } else {
-    PrintF("@%d[@%d]", expr->obj()->num(), expr->key()->num());
-  }
-}
-
-
-void TextInstructionPrinter::VisitCall(Call* expr) {
-  PrintF("@%d(", expr->expression()->num());
-  ZoneList<Expression*>* arguments = expr->arguments();
-  for (int i = 0, len = arguments->length(); i < len; i++) {
-    if (i != 0) PrintF(", ");
-    PrintF("@%d", arguments->at(i)->num());
-  }
-  PrintF(")");
-}
-
-
-void TextInstructionPrinter::VisitCallNew(CallNew* expr) {
-  PrintF("new @%d(", expr->expression()->num());
-  ZoneList<Expression*>* arguments = expr->arguments();
-  for (int i = 0, len = arguments->length(); i < len; i++) {
-    if (i != 0) PrintF(", ");
-    PrintF("@%d", arguments->at(i)->num());
-  }
-  PrintF(")");
-}
-
-
-void TextInstructionPrinter::VisitCallRuntime(CallRuntime* expr) {
-  PrintF("%s(", *expr->name()->ToCString());
-  ZoneList<Expression*>* arguments = expr->arguments();
-  for (int i = 0, len = arguments->length(); i < len; i++) {
-    if (i != 0) PrintF(", ");
-    PrintF("@%d", arguments->at(i)->num());
-  }
-  PrintF(")");
-}
-
-
-void TextInstructionPrinter::VisitUnaryOperation(UnaryOperation* expr) {
-  PrintF("%s(@%d)", Token::String(expr->op()), expr->expression()->num());
-}
-
-
-void TextInstructionPrinter::VisitCountOperation(CountOperation* expr) {
-  if (expr->is_prefix()) {
-    PrintF("%s@%d", Token::String(expr->op()), expr->expression()->num());
-  } else {
-    PrintF("@%d%s", expr->expression()->num(), Token::String(expr->op()));
-  }
-
-  if (expr->num() != AstNode::kNoNumber) {
-    PrintF(" ;; D%d", expr->num());
-  }
-}
-
-
-void TextInstructionPrinter::VisitBinaryOperation(BinaryOperation* expr) {
-  ASSERT(expr->op() != Token::COMMA);
-  ASSERT(expr->op() != Token::OR);
-  ASSERT(expr->op() != Token::AND);
-  PrintF("@%d %s @%d",
-         expr->left()->num(),
-         Token::String(expr->op()),
-         expr->right()->num());
-}
-
-
-void TextInstructionPrinter::VisitCompareOperation(CompareOperation* expr) {
-  PrintF("@%d %s @%d",
-         expr->left()->num(),
-         Token::String(expr->op()),
-         expr->right()->num());
-}
-
-
-void TextInstructionPrinter::VisitThisFunction(ThisFunction* expr) {
-  PrintF("ThisFunction");
-}
-
-
-static int node_count = 0;
-static int instruction_count = 0;
-
-
-void Node::AssignNodeNumber() {
-  set_number(node_count++);
-}
-
-
-void Node::PrintReachingDefinitions() {
-  if (rd_.rd_in() != NULL) {
-    ASSERT(rd_.kill() != NULL && rd_.gen() != NULL);
-
-    PrintF("RD_in = ");
-    rd_.rd_in()->Print();
-    PrintF("\n");
-
-    PrintF("RD_kill = ");
-    rd_.kill()->Print();
-    PrintF("\n");
-
-    PrintF("RD_gen = ");
-    rd_.gen()->Print();
-    PrintF("\n");
-  }
-}
-
-
-void ExitNode::PrintText() {
-  PrintReachingDefinitions();
-  PrintF("L%d: Exit\n\n", number());
-}
-
-
-void BlockNode::PrintText() {
-  PrintReachingDefinitions();
-  // Print the instructions in the block.
-  PrintF("L%d: Block\n", number());
-  TextInstructionPrinter printer;
-  for (int i = 0, len = instructions_.length(); i < len; i++) {
-    AstNode* instr = instructions_[i];
-    // Print a star next to dead instructions.
-    if (instr->AsExpression() != NULL && instr->AsExpression()->is_live()) {
-      PrintF("  ");
-    } else {
-      PrintF("* ");
-    }
-    PrintF("%d ", printer.NextNumber());
-    printer.Visit(instr);
-    printer.AssignNumber(instr);
-    PrintF("\n");
-  }
-  PrintF("goto L%d\n\n", successor_->number());
-}
-
-
-void BranchNode::PrintText() {
-  PrintReachingDefinitions();
-  PrintF("L%d: Branch\n", number());
-  PrintF("goto (L%d, L%d)\n\n", successor0_->number(), successor1_->number());
-}
-
-
-void JoinNode::PrintText() {
-  PrintReachingDefinitions();
-  PrintF("L%d: Join(", number());
-  for (int i = 0, len = predecessors_.length(); i < len; i++) {
-    if (i != 0) PrintF(", ");
-    PrintF("L%d", predecessors_[i]->number());
-  }
-  PrintF(")\ngoto L%d\n\n", successor_->number());
-}
-
-
-void FlowGraph::PrintText(FunctionLiteral* fun, ZoneList<Node*>* postorder) {
-  PrintF("\n========\n");
-  PrintF("name = %s\n", *fun->name()->ToCString());
-
-  // Number nodes and instructions in reverse postorder.
-  node_count = 0;
-  instruction_count = 0;
-  for (int i = postorder->length() - 1; i >= 0; i--) {
-    postorder->at(i)->AssignNodeNumber();
-  }
-
-  // Print basic blocks in reverse postorder.
-  for (int i = postorder->length() - 1; i >= 0; i--) {
-    postorder->at(i)->PrintText();
-  }
-}
-
-#endif  // DEBUG
-
-
 } }  // namespace v8::internal