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+// 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
+// with the distribution.
+// * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived
+// from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// 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 "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);
+ bool result_assigned() const { return result_assigned_; }
+
+ private:
+ Variable* result_;
+
+ // We are not tracking result usage via the result_'s use
+ // counts (we leave the accurate computation to the
+ // usage analyzer). Instead we simple remember if
+ // there was ever an assignment to result_.
+ bool result_assigned_;
+
+ // To avoid storing to .result all the time, we eliminate some of
+ // the stores by keeping track of whether or not we're sure .result
+ // will be overwritten anyway. This is a bit more tricky than what I
+ // was hoping for
+ bool is_set_;
+ bool in_try_;
+
+ Expression* SetResult(Expression* value) {
+ result_assigned_ = true;
+ VariableProxy* result_proxy = new VariableProxy(result_);
+ return new Assignment(Token::ASSIGN, result_proxy, value,
+ RelocInfo::kNoPosition);
+ }
+
+ // Node visitors.
+#define DEF_VISIT(type) \
+ virtual void Visit##type(type* node);
+ AST_NODE_LIST(DEF_VISIT)
+#undef DEF_VISIT
+
+ void VisitIterationStatement(IterationStatement* stmt);
+};
+
+
+void Processor::Process(ZoneList<Statement*>* statements) {
+ for (int i = statements->length() - 1; i >= 0; --i) {
+ Visit(statements->at(i));
+ }
+}
+
+
+void Processor::VisitBlock(Block* node) {
+ // An initializer block is the rewritten form of a variable declaration
+ // with initialization expressions. The initializer block contains the
+ // list of assignments corresponding to the initialization expressions.
+ // While unclear from the spec (ECMA-262, 3rd., 12.2), the value of
+ // a variable declaration with initialization expression is 'undefined'
+ // with some JS VMs: For instance, using smjs, print(eval('var x = 7'))
+ // returns 'undefined'. To obtain the same behavior with v8, we need
+ // to prevent rewriting in that case.
+ if (!node->is_initializer_block()) Process(node->statements());
+}
+
+
+void Processor::VisitExpressionStatement(ExpressionStatement* node) {
+ // Rewrite : <x>; -> .result = <x>;
+ if (!is_set_) {
+ node->set_expression(SetResult(node->expression()));
+ if (!in_try_) is_set_ = true;
+ }
+}
+
+
+void Processor::VisitIfStatement(IfStatement* node) {
+ // Rewrite both then and else parts (reversed).
+ bool save = is_set_;
+ Visit(node->else_statement());
+ bool set_after_then = is_set_;
+ is_set_ = save;
+ Visit(node->then_statement());
+ is_set_ = is_set_ && set_after_then;
+}
+
+
+void Processor::VisitIterationStatement(IterationStatement* node) {
+ // Rewrite the body.
+ bool set_after_loop = is_set_;
+ Visit(node->body());
+ is_set_ = is_set_ && set_after_loop;
+}
+
+
+void Processor::VisitDoWhileStatement(DoWhileStatement* node) {
+ VisitIterationStatement(node);
+}
+
+
+void Processor::VisitWhileStatement(WhileStatement* node) {
+ VisitIterationStatement(node);
+}
+
+
+void Processor::VisitForStatement(ForStatement* node) {
+ VisitIterationStatement(node);
+}
+
+
+void Processor::VisitForInStatement(ForInStatement* node) {
+ VisitIterationStatement(node);
+}
+
+
+void Processor::VisitTryCatchStatement(TryCatchStatement* node) {
+ // Rewrite both try and catch blocks (reversed order).
+ bool set_after_catch = is_set_;
+ Visit(node->catch_block());
+ is_set_ = is_set_ && set_after_catch;
+ bool save = in_try_;
+ in_try_ = true;
+ Visit(node->try_block());
+ in_try_ = save;
+}
+
+
+void Processor::VisitTryFinallyStatement(TryFinallyStatement* node) {
+ // Rewrite both try and finally block (reversed order).
+ Visit(node->finally_block());
+ bool save = in_try_;
+ in_try_ = true;
+ Visit(node->try_block());
+ in_try_ = save;
+}
+
+
+void Processor::VisitSwitchStatement(SwitchStatement* node) {
+ // Rewrite statements in all case clauses in reversed order.
+ ZoneList<CaseClause*>* clauses = node->cases();
+ bool set_after_switch = is_set_;
+ for (int i = clauses->length() - 1; i >= 0; --i) {
+ CaseClause* clause = clauses->at(i);
+ Process(clause->statements());
+ }
+ is_set_ = is_set_ && set_after_switch;
+}
+
+
+void Processor::VisitContinueStatement(ContinueStatement* node) {
+ is_set_ = false;
+}
+
+
+void Processor::VisitBreakStatement(BreakStatement* node) {
+ is_set_ = false;
+}
+
+
+// Do nothing:
+void Processor::VisitDeclaration(Declaration* node) {}
+void Processor::VisitEmptyStatement(EmptyStatement* node) {}
+void Processor::VisitReturnStatement(ReturnStatement* node) {}
+void Processor::VisitWithEnterStatement(WithEnterStatement* node) {}
+void Processor::VisitWithExitStatement(WithExitStatement* node) {}
+void Processor::VisitDebuggerStatement(DebuggerStatement* node) {}
+
+
+// Expressions are never visited yet.
+void Processor::VisitFunctionLiteral(FunctionLiteral* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitSharedFunctionInfoLiteral(
+ SharedFunctionInfoLiteral* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitConditional(Conditional* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitVariableProxy(VariableProxy* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitLiteral(Literal* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitRegExpLiteral(RegExpLiteral* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitArrayLiteral(ArrayLiteral* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitObjectLiteral(ObjectLiteral* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitCatchExtensionObject(CatchExtensionObject* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitAssignment(Assignment* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitThrow(Throw* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitProperty(Property* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitCall(Call* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitCallNew(CallNew* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitCallRuntime(CallRuntime* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitUnaryOperation(UnaryOperation* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitIncrementOperation(IncrementOperation* node) {
+ UNREACHABLE();
+}
+
+
+void Processor::VisitCountOperation(CountOperation* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitBinaryOperation(BinaryOperation* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitCompareOperation(CompareOperation* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitCompareToNull(CompareToNull* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+void Processor::VisitThisFunction(ThisFunction* node) {
+ USE(node);
+ UNREACHABLE();
+}
+
+
+// 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::Rewrite(CompilationInfo* info) {
+ FunctionLiteral* function = info->function();
+ ASSERT(function != NULL);
+ Scope* scope = function->scope();
+ ASSERT(scope != NULL);
+ if (scope->is_function_scope()) return true;
+
+ ZoneList<Statement*>* body = function->body();
+ if (!body->is_empty()) {
+ Variable* result = scope->NewTemporary(
+ info->isolate()->factory()->result_symbol());
+ Processor processor(result);
+ processor.Process(body);
+ if (processor.HasStackOverflow()) return false;
+
+ 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
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