Remove some dead code.

src/rewriter.cc

-// Copyright 2010 the V8 project authors. All rights reserved.
+// Copyright 2011 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
 //       with the distribution.
@@ skipping 17 matching lines @@
 
 #include "rewriter.h"
 
 #include "ast.h"
 #include "compiler.h"
 #include "scopes.h"
 
 namespace v8 {
 namespace internal {
 
-class AstOptimizer: public AstVisitor {
- public:
-  explicit AstOptimizer() : has_function_literal_(false) {}
-
-  void Optimize(ZoneList<Statement*>* statements);
-
- private:
-  // Used for loop condition analysis.  Cleared before visiting a loop
-  // condition, set when a function literal is visited.
-  bool has_function_literal_;
-
-  // Helpers
-  void OptimizeArguments(ZoneList<Expression*>* arguments);
-
-  // Node visitors.
-#define DEF_VISIT(type) \
-  virtual void Visit##type(type* node);
-  AST_NODE_LIST(DEF_VISIT)
-#undef DEF_VISIT
-
-  DISALLOW_COPY_AND_ASSIGN(AstOptimizer);
-};
-
-
-void AstOptimizer::Optimize(ZoneList<Statement*>* statements) {
-  int len = statements->length();
-  for (int i = 0; i < len; i++) {
-    Visit(statements->at(i));
-  }
-}
-
-
-void AstOptimizer::OptimizeArguments(ZoneList<Expression*>* arguments) {
-  for (int i = 0; i < arguments->length(); i++) {
-    Visit(arguments->at(i));
-  }
-}
-
-
-void AstOptimizer::VisitBlock(Block* node) {
-  Optimize(node->statements());
-}
-
-
-void AstOptimizer::VisitExpressionStatement(ExpressionStatement* node) {
-  node->expression()->set_no_negative_zero(true);
-  Visit(node->expression());
-}
-
-
-void AstOptimizer::VisitIfStatement(IfStatement* node) {
-  node->condition()->set_no_negative_zero(true);
-  Visit(node->condition());
-  Visit(node->then_statement());
-  if (node->HasElseStatement()) {
-    Visit(node->else_statement());
-  }
-}
-
-
-void AstOptimizer::VisitDoWhileStatement(DoWhileStatement* node) {
-  node->cond()->set_no_negative_zero(true);
-  Visit(node->cond());
-  Visit(node->body());
-}
-
-
-void AstOptimizer::VisitWhileStatement(WhileStatement* node) {
-  has_function_literal_ = false;
-  node->cond()->set_no_negative_zero(true);
-  Visit(node->cond());
-  node->set_may_have_function_literal(has_function_literal_);
-  Visit(node->body());
-}
-
-
-void AstOptimizer::VisitForStatement(ForStatement* node) {
-  if (node->init() != NULL) {
-    Visit(node->init());
-  }
-  if (node->cond() != NULL) {
-    has_function_literal_ = false;
-    node->cond()->set_no_negative_zero(true);
-    Visit(node->cond());
-    node->set_may_have_function_literal(has_function_literal_);
-  }
-  Visit(node->body());
-  if (node->next() != NULL) {
-    Visit(node->next());
-  }
-}
-
-
-void AstOptimizer::VisitForInStatement(ForInStatement* node) {
-  Visit(node->each());
-  Visit(node->enumerable());
-  Visit(node->body());
-}
-
-
-void AstOptimizer::VisitTryCatchStatement(TryCatchStatement* node) {
-  Visit(node->try_block());
-  Visit(node->catch_var());
-  Visit(node->catch_block());
-}
-
-
-void AstOptimizer::VisitTryFinallyStatement(TryFinallyStatement* node) {
-  Visit(node->try_block());
-  Visit(node->finally_block());
-}
-
-
-void AstOptimizer::VisitSwitchStatement(SwitchStatement* node) {
-  node->tag()->set_no_negative_zero(true);
-  Visit(node->tag());
-  for (int i = 0; i < node->cases()->length(); i++) {
-    CaseClause* clause = node->cases()->at(i);
-    if (!clause->is_default()) {
-      Visit(clause->label());
-    }
-    Optimize(clause->statements());
-  }
-}
-
-
-void AstOptimizer::VisitContinueStatement(ContinueStatement* node) {
-  USE(node);
-}
-
-
-void AstOptimizer::VisitBreakStatement(BreakStatement* node) {
-  USE(node);
-}
-
-
-void AstOptimizer::VisitDeclaration(Declaration* node) {
-  // Will not be reached by the current optimizations.
-  USE(node);
-}
-
-
-void AstOptimizer::VisitEmptyStatement(EmptyStatement* node) {
-  USE(node);
-}
-
-
-void AstOptimizer::VisitReturnStatement(ReturnStatement* node) {
-  Visit(node->expression());
-}
-
-
-void AstOptimizer::VisitWithEnterStatement(WithEnterStatement* node) {
-  Visit(node->expression());
-}
-
-
-void AstOptimizer::VisitWithExitStatement(WithExitStatement* node) {
-  USE(node);
-}
-
-
-void AstOptimizer::VisitDebuggerStatement(DebuggerStatement* node) {
-  USE(node);
-}
-
-
-void AstOptimizer::VisitFunctionLiteral(FunctionLiteral* node) {
-  has_function_literal_ = true;
-}
-
-
-void AstOptimizer::VisitSharedFunctionInfoLiteral(
-    SharedFunctionInfoLiteral* node) {
-  USE(node);
-}
-
-
-void AstOptimizer::VisitConditional(Conditional* node) {
-  node->condition()->set_no_negative_zero(true);
-  Visit(node->condition());
-  Visit(node->then_expression());
-  Visit(node->else_expression());
-}
-
-
-void AstOptimizer::VisitVariableProxy(VariableProxy* node) {
-  Variable* var = node->AsVariable();
-  if (var != NULL) {
-    if (var->type()->IsKnown()) {
-      node->type()->CopyFrom(var->type());
-    } else if (node->type()->IsLikelySmi()) {
-      var->type()->SetAsLikelySmi();
-    }
-
-    if (FLAG_safe_int32_compiler) {
-      if (var->IsStackAllocated() &&
-          !var->is_arguments() &&
-          var->mode() != Variable::CONST) {
-        node->set_side_effect_free(true);
-      }
-    }
-  }
-}
-
-
-void AstOptimizer::VisitLiteral(Literal* node) {
-  Handle<Object> literal = node->handle();
-  if (literal->IsSmi()) {
-    node->type()->SetAsLikelySmi();
-    node->set_side_effect_free(true);
-  } else if (literal->IsHeapNumber()) {
-    if (node->to_int32()) {
-      // Any HeapNumber has an int32 value if it is the input to a bit op.
-      node->set_side_effect_free(true);
-    } else {
-      double double_value = HeapNumber::cast(*literal)->value();
-      int32_t int32_value = DoubleToInt32(double_value);
-      node->set_side_effect_free(double_value == int32_value);
-    }
-  }
-}
-
-
-void AstOptimizer::VisitRegExpLiteral(RegExpLiteral* node) {
-  USE(node);
-}
-
-
-void AstOptimizer::VisitArrayLiteral(ArrayLiteral* node) {
-  for (int i = 0; i < node->values()->length(); i++) {
-    Visit(node->values()->at(i));
-  }
-}
-
-void AstOptimizer::VisitObjectLiteral(ObjectLiteral* node) {
-  for (int i = 0; i < node->properties()->length(); i++) {
-    Visit(node->properties()->at(i)->key());
-    Visit(node->properties()->at(i)->value());
-  }
-}
-
-
-void AstOptimizer::VisitCatchExtensionObject(CatchExtensionObject* node) {
-  Visit(node->key());
-  Visit(node->value());
-}
-
-
-void AstOptimizer::VisitAssignment(Assignment* node) {
-  switch (node->op()) {
-    case Token::INIT_VAR:
-    case Token::INIT_CONST:
-    case Token::ASSIGN:
-      // No type can be infered from the general assignment.
-      break;
-    case Token::ASSIGN_BIT_OR:
-    case Token::ASSIGN_BIT_XOR:
-    case Token::ASSIGN_BIT_AND:
-    case Token::ASSIGN_SHL:
-    case Token::ASSIGN_SAR:
-    case Token::ASSIGN_SHR:
-      node->type()->SetAsLikelySmiIfUnknown();
-      node->target()->type()->SetAsLikelySmiIfUnknown();
-      node->value()->type()->SetAsLikelySmiIfUnknown();
-      node->value()->set_to_int32(true);
-      node->value()->set_no_negative_zero(true);
-      break;
-    case Token::ASSIGN_ADD:
-    case Token::ASSIGN_SUB:
-    case Token::ASSIGN_MUL:
-    case Token::ASSIGN_DIV:
-    case Token::ASSIGN_MOD:
-      if (node->type()->IsLikelySmi()) {
-        node->target()->type()->SetAsLikelySmiIfUnknown();
-        node->value()->type()->SetAsLikelySmiIfUnknown();
-      }
-      break;
-    default:
-      UNREACHABLE();
-      break;
-  }
-
-  Visit(node->target());
-  Visit(node->value());
-
-  switch (node->op()) {
-    case Token::INIT_VAR:
-    case Token::INIT_CONST:
-    case Token::ASSIGN:
-      // Pure assignment copies the type from the value.
-      node->type()->CopyFrom(node->value()->type());
-      break;
-    case Token::ASSIGN_BIT_OR:
-    case Token::ASSIGN_BIT_XOR:
-    case Token::ASSIGN_BIT_AND:
-    case Token::ASSIGN_SHL:
-    case Token::ASSIGN_SAR:
-    case Token::ASSIGN_SHR:
-      // Should have been setup above already.
-      break;
-    case Token::ASSIGN_ADD:
-    case Token::ASSIGN_SUB:
-    case Token::ASSIGN_MUL:
-    case Token::ASSIGN_DIV:
-    case Token::ASSIGN_MOD:
-      if (node->type()->IsUnknown()) {
-        if (node->target()->type()->IsLikelySmi() ||
-            node->value()->type()->IsLikelySmi()) {
-          node->type()->SetAsLikelySmi();
-        }
-      }
-      break;
-    default:
-      UNREACHABLE();
-      break;
-  }
-
-  // Since this is an assignment. We have to propagate this node's type to the
-  // variable.
-  VariableProxy* proxy = node->target()->AsVariableProxy();
-  if (proxy != NULL) {
-    Variable* var = proxy->AsVariable();
-    if (var != NULL) {
-      StaticType* var_type = var->type();
-      if (var_type->IsUnknown()) {
-        var_type->CopyFrom(node->type());
-      } else if (var_type->IsLikelySmi()) {
-        // We do not reset likely types to Unknown.
-      }
-    }
-  }
-}
-
-
-void AstOptimizer::VisitThrow(Throw* node) {
-  Visit(node->exception());
-}
-
-
-void AstOptimizer::VisitProperty(Property* node) {
-  node->key()->set_no_negative_zero(true);
-  Visit(node->obj());
-  Visit(node->key());
-}
-
-
-void AstOptimizer::VisitCall(Call* node) {
-  Visit(node->expression());
-  OptimizeArguments(node->arguments());
-}
-
-
-void AstOptimizer::VisitCallNew(CallNew* node) {
-  Visit(node->expression());
-  OptimizeArguments(node->arguments());
-}
-
-
-void AstOptimizer::VisitCallRuntime(CallRuntime* node) {
-  OptimizeArguments(node->arguments());
-}
-
-
-void AstOptimizer::VisitUnaryOperation(UnaryOperation* node) {
-  if (node->op() == Token::ADD || node->op() == Token::SUB) {
-    node->expression()->set_no_negative_zero(node->no_negative_zero());
-  } else {
-    node->expression()->set_no_negative_zero(true);
-  }
-  Visit(node->expression());
-  if (FLAG_safe_int32_compiler) {
-    switch (node->op()) {
-      case Token::BIT_NOT:
-        node->expression()->set_no_negative_zero(true);
-        node->expression()->set_to_int32(true);
-        // Fall through.
-      case Token::ADD:
-      case Token::SUB:
-        node->set_side_effect_free(node->expression()->side_effect_free());
-        break;
-      case Token::NOT:
-      case Token::DELETE:
-      case Token::TYPEOF:
-      case Token::VOID:
-        break;
-      default:
-        UNREACHABLE();
-        break;
-    }
-  } else if (node->op() == Token::BIT_NOT) {
-    node->expression()->set_to_int32(true);
-  }
-}
-
-
-void AstOptimizer::VisitIncrementOperation(IncrementOperation* node) {
-  UNREACHABLE();
-}
-
-
-void AstOptimizer::VisitCountOperation(CountOperation* node) {
-  // Count operations assume that they work on Smis.
-  node->expression()->set_no_negative_zero(node->is_prefix() ?
-                                           true :
-                                           node->no_negative_zero());
-  node->type()->SetAsLikelySmiIfUnknown();
-  node->expression()->type()->SetAsLikelySmiIfUnknown();
-  Visit(node->expression());
-}
-
-
-static bool CouldBeNegativeZero(AstNode* node) {
-  Literal* literal = node->AsLiteral();
-  if (literal != NULL) {
-    Handle<Object> handle = literal->handle();
-    if (handle->IsString() || handle->IsSmi()) {
-      return false;
-    } else if (handle->IsHeapNumber()) {
-      double double_value = HeapNumber::cast(*handle)->value();
-      if (double_value != 0) {
-        return false;
-      }
-    }
-  }
-  BinaryOperation* binary = node->AsBinaryOperation();
-  if (binary != NULL && Token::IsBitOp(binary->op())) {
-    return false;
-  }
-  return true;
-}
-
-
-static bool CouldBePositiveZero(AstNode* node) {
-  Literal* literal = node->AsLiteral();
-  if (literal != NULL) {
-    Handle<Object> handle = literal->handle();
-    if (handle->IsSmi()) {
-      if (Smi::cast(*handle) != Smi::FromInt(0)) {
-        return false;
-      }
-    } else if (handle->IsHeapNumber()) {
-      // Heap number literal can't be +0, because that's a Smi.
-      return false;
-    }
-  }
-  return true;
-}
-
-
-void AstOptimizer::VisitBinaryOperation(BinaryOperation* node) {
-  // Depending on the operation we can propagate this node's type down the
-  // AST nodes.
-  Token::Value op = node->op();
-  switch (op) {
-    case Token::COMMA:
-    case Token::OR:
-      node->left()->set_no_negative_zero(true);
-      node->right()->set_no_negative_zero(node->no_negative_zero());
-      break;
-    case Token::AND:
-      node->left()->set_no_negative_zero(node->no_negative_zero());
-      node->right()->set_no_negative_zero(node->no_negative_zero());
-      break;
-    case Token::BIT_OR:
-    case Token::BIT_XOR:
-    case Token::BIT_AND:
-    case Token::SHL:
-    case Token::SAR:
-    case Token::SHR:
-      node->type()->SetAsLikelySmiIfUnknown();
-      node->left()->type()->SetAsLikelySmiIfUnknown();
-      node->right()->type()->SetAsLikelySmiIfUnknown();
-      node->left()->set_to_int32(true);
-      node->right()->set_to_int32(true);
-      node->left()->set_no_negative_zero(true);
-      node->right()->set_no_negative_zero(true);
-      break;
-    case Token::MUL: {
-      VariableProxy* lvar_proxy = node->left()->AsVariableProxy();
-      VariableProxy* rvar_proxy = node->right()->AsVariableProxy();
-      if (lvar_proxy != NULL && rvar_proxy != NULL) {
-        Variable* lvar = lvar_proxy->AsVariable();
-        Variable* rvar = rvar_proxy->AsVariable();
-        if (lvar != NULL && rvar != NULL) {
-          if (lvar->mode() == Variable::VAR && rvar->mode() == Variable::VAR) {
-            Slot* lslot = lvar->AsSlot();
-            Slot* rslot = rvar->AsSlot();
-            if (lslot->type() == rslot->type() &&
-                (lslot->type() == Slot::PARAMETER ||
-                 lslot->type() == Slot::LOCAL) &&
-                lslot->index() == rslot->index()) {
-              // A number squared doesn't give negative zero.
-              node->set_no_negative_zero(true);
-            }
-          }
-        }
-      }
-    }
-    case Token::ADD:
-    case Token::SUB:
-    case Token::DIV:
-    case Token::MOD: {
-      if (node->type()->IsLikelySmi()) {
-        node->left()->type()->SetAsLikelySmiIfUnknown();
-        node->right()->type()->SetAsLikelySmiIfUnknown();
-      }
-      if (op == Token::ADD && (!CouldBeNegativeZero(node->left()) ||
-                               !CouldBeNegativeZero(node->right()))) {
-        node->left()->set_no_negative_zero(true);
-        node->right()->set_no_negative_zero(true);
-      } else if (op == Token::SUB && (!CouldBeNegativeZero(node->left()) ||
-                                      !CouldBePositiveZero(node->right()))) {
-        node->left()->set_no_negative_zero(true);
-        node->right()->set_no_negative_zero(true);
-      } else {
-        node->left()->set_no_negative_zero(node->no_negative_zero());
-        node->right()->set_no_negative_zero(node->no_negative_zero());
-      }
-      if (node->op() == Token::DIV) {
-        node->right()->set_no_negative_zero(false);
-      } else if (node->op() == Token::MOD) {
-        node->right()->set_no_negative_zero(true);
-      }
-      break;
-    }
-    default:
-      UNREACHABLE();
-      break;
-  }
-
-  Visit(node->left());
-  Visit(node->right());
-
-  // After visiting the operand nodes we have to check if this node's type
-  // can be updated. If it does, then we can push that information down
-  // towards the leaves again if the new information is an upgrade over the
-  // previous type of the operand nodes.
-  if (node->type()->IsUnknown()) {
-    if (node->left()->type()->IsLikelySmi() ||
-        node->right()->type()->IsLikelySmi()) {
-      node->type()->SetAsLikelySmi();
-    }
-    if (node->type()->IsLikelySmi()) {
-      // The type of this node changed to LIKELY_SMI. Propagate this knowledge
-      // down through the nodes.
-      if (node->left()->type()->IsUnknown()) {
-        node->left()->type()->SetAsLikelySmi();
-        Visit(node->left());
-      }
-      if (node->right()->type()->IsUnknown()) {
-        node->right()->type()->SetAsLikelySmi();
-        Visit(node->right());
-      }
-    }
-  }
-
-  if (FLAG_safe_int32_compiler) {
-    switch (node->op()) {
-      case Token::COMMA:
-      case Token::OR:
-      case Token::AND:
-        break;
-      case Token::BIT_OR:
-      case Token::BIT_XOR:
-      case Token::BIT_AND:
-      case Token::SHL:
-      case Token::SAR:
-      case Token::SHR:
-        // Add one to the number of bit operations in this expression.
-        node->set_num_bit_ops(1);
-        // Fall through.
-      case Token::ADD:
-      case Token::SUB:
-      case Token::MUL:
-      case Token::DIV:
-      case Token::MOD:
-        node->set_side_effect_free(node->left()->side_effect_free() &&
-                                   node->right()->side_effect_free());
-        node->set_num_bit_ops(node->num_bit_ops() +
-                                  node->left()->num_bit_ops() +
-                                  node->right()->num_bit_ops());
-        if (!node->no_negative_zero() && node->op() == Token::MUL) {
-          node->set_side_effect_free(false);
-        }
-        break;
-      default:
-        UNREACHABLE();
-        break;
-    }
-  }
-}
-
-
-void AstOptimizer::VisitCompareOperation(CompareOperation* node) {
-  if (node->type()->IsKnown()) {
-    // Propagate useful information down towards the leaves.
-    node->left()->type()->SetAsLikelySmiIfUnknown();
-    node->right()->type()->SetAsLikelySmiIfUnknown();
-  }
-
-  node->left()->set_no_negative_zero(true);
-  // Only [[HasInstance]] has the right argument passed unchanged to it.
-  node->right()->set_no_negative_zero(true);
-
-  Visit(node->left());
-  Visit(node->right());
-
-  // After visiting the operand nodes we have to check if this node's type
-  // can be updated. If it does, then we can push that information down
-  // towards the leaves again if the new information is an upgrade over the
-  // previous type of the operand nodes.
-  if (node->type()->IsUnknown()) {
-    if (node->left()->type()->IsLikelySmi() ||
-        node->right()->type()->IsLikelySmi()) {
-      node->type()->SetAsLikelySmi();
-    }
-    if (node->type()->IsLikelySmi()) {
-      // The type of this node changed to LIKELY_SMI. Propagate this knowledge
-      // down through the nodes.
-      if (node->left()->type()->IsUnknown()) {
-        node->left()->type()->SetAsLikelySmi();
-        Visit(node->left());
-      }
-      if (node->right()->type()->IsUnknown()) {
-        node->right()->type()->SetAsLikelySmi();
-        Visit(node->right());
-      }
-    }
-  }
-}
-
-
-void AstOptimizer::VisitCompareToNull(CompareToNull* node) {
-  Visit(node->expression());
-}
-
-
-void AstOptimizer::VisitThisFunction(ThisFunction* node) {
-  USE(node);
-}
-
-
 class Processor: public AstVisitor {
  public:
   explicit Processor(Variable* result)
       : result_(result),
         result_assigned_(false),
         is_set_(false),
         in_try_(false) {
   }
 
   void Process(ZoneList<Statement*>* statements);
@@ skipping 306 matching lines @@
     if (processor.result_assigned()) {
       VariableProxy* result_proxy = new VariableProxy(result);
       body->Add(new ReturnStatement(result_proxy));
     }
   }
 
   return true;
 }
 
 
-// Assumes code has been parsed and scopes have been analyzed.  Mutates the
-// AST, so the AST should not continue to be used in the case of failure.
-bool Rewriter::Analyze(CompilationInfo* info) {
-  FunctionLiteral* function = info->function();
-  ASSERT(function != NULL && function->scope() != NULL);
-
-  ZoneList<Statement*>* body = function->body();
-  if (FLAG_optimize_ast && !body->is_empty()) {
-    AstOptimizer optimizer;
-    optimizer.Optimize(body);
-    if (optimizer.HasStackOverflow()) return false;
-  }
-  return true;
-}
-
-
 } }  // namespace v8::internal