// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/interpreter/bytecode-generator.h"

#include <stack>

#include "src/compiler.h"
#include "src/interpreter/control-flow-builders.h"
#include "src/objects.h"
#include "src/scopes.h"
#include "src/token.h"

namespace v8 {
namespace internal {
namespace interpreter {


// Scoped class for tracking control statements entered by the
// visitor. The pattern derives AstGraphBuilder::ControlScope.
class BytecodeGenerator::ControlScope BASE_EMBEDDED {
 public:
  explicit ControlScope(BytecodeGenerator* generator)
      : generator_(generator), outer_(generator->control_scope()) {
    generator_->set_control_scope(this);
  }
  virtual ~ControlScope() { generator_->set_control_scope(outer()); }

  void Break(Statement* stmt) { PerformCommand(CMD_BREAK, stmt); }
  void Continue(Statement* stmt) { PerformCommand(CMD_CONTINUE, stmt); }

 protected:
  enum Command { CMD_BREAK, CMD_CONTINUE };
  void PerformCommand(Command command, Statement* statement);
  virtual bool Execute(Command command, Statement* statement) = 0;

  BytecodeGenerator* generator() const { return generator_; }
  ControlScope* outer() const { return outer_; }

 private:
  BytecodeGenerator* generator_;
  ControlScope* outer_;

  DISALLOW_COPY_AND_ASSIGN(ControlScope);
};


// Scoped class for enabling 'break' and 'continue' in iteration
// constructs, e.g. do...while, while..., for...
class BytecodeGenerator::ControlScopeForIteration
    : public BytecodeGenerator::ControlScope {
 public:
  ControlScopeForIteration(BytecodeGenerator* generator,
                           IterationStatement* statement,
                           LoopBuilder* loop_builder)
      : ControlScope(generator),
        statement_(statement),
        loop_builder_(loop_builder) {}

 protected:
  virtual bool Execute(Command command, Statement* statement) {
    if (statement != statement_) return false;
    switch (command) {
      case CMD_BREAK:
        loop_builder_->Break();
        return true;
      case CMD_CONTINUE:
        loop_builder_->Continue();
        return true;
    }
    return false;
  }

 private:
  Statement* statement_;
  LoopBuilder* loop_builder_;
};


void BytecodeGenerator::ControlScope::PerformCommand(Command command,
                                                     Statement* statement) {
  ControlScope* current = this;
  do {
    if (current->Execute(command, statement)) return;
    current = current->outer();
  } while (current != nullptr);
  UNREACHABLE();
}


BytecodeGenerator::BytecodeGenerator(Isolate* isolate, Zone* zone)
    : builder_(isolate, zone),
      info_(nullptr),
      scope_(nullptr),
      control_scope_(nullptr) {
  InitializeAstVisitor(isolate, zone);
}


BytecodeGenerator::~BytecodeGenerator() {}


Handle<BytecodeArray> BytecodeGenerator::MakeBytecode(CompilationInfo* info) {
  set_info(info);
  set_scope(info->scope());

  // This a temporary guard (oth).
  DCHECK(scope()->is_function_scope());

  builder()->set_parameter_count(info->num_parameters_including_this());
  builder()->set_locals_count(scope()->num_stack_slots());

  // Visit implicit declaration of the function name.
  if (scope()->is_function_scope() && scope()->function() != NULL) {
    VisitVariableDeclaration(scope()->function());
  }

  // Visit declarations within the function scope.
  VisitDeclarations(scope()->declarations());

  // Visit statements in the function body.
  VisitStatements(info->literal()->body());

  set_scope(nullptr);
  set_info(nullptr);
  return builder_.ToBytecodeArray();
}


void BytecodeGenerator::VisitBlock(Block* node) {
  builder()->EnterBlock();
  if (node->scope() == NULL) {
    // Visit statements in the same scope, no declarations.
    VisitStatements(node->statements());
  } else {
    // Visit declarations and statements in a block scope.
    if (node->scope()->ContextLocalCount() > 0) {
      UNIMPLEMENTED();
    } else {
      VisitDeclarations(node->scope()->declarations());
      VisitStatements(node->statements());
    }
  }
  builder()->LeaveBlock();
}


void BytecodeGenerator::VisitVariableDeclaration(VariableDeclaration* decl) {
  Variable* variable = decl->proxy()->var();
  switch (variable->location()) {
    case VariableLocation::GLOBAL:
    case VariableLocation::UNALLOCATED:
      UNIMPLEMENTED();
      break;
    case VariableLocation::PARAMETER:
    case VariableLocation::LOCAL:
      // Details stored in scope, i.e. variable index.
      break;
    case VariableLocation::CONTEXT:
    case VariableLocation::LOOKUP:
      UNIMPLEMENTED();
      break;
  }
}


void BytecodeGenerator::VisitFunctionDeclaration(FunctionDeclaration* decl) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitImportDeclaration(ImportDeclaration* decl) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitExportDeclaration(ExportDeclaration* decl) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitExpressionStatement(ExpressionStatement* stmt) {
  Visit(stmt->expression());
}


void BytecodeGenerator::VisitEmptyStatement(EmptyStatement* stmt) {
  // TODO(oth): For control-flow it could be useful to signal empty paths here.
}


void BytecodeGenerator::VisitIfStatement(IfStatement* stmt) {
  // TODO(oth): Spot easy cases where there code would not need to
  // emit the then block or the else block, e.g. condition is
  // obviously true/1/false/0.

  BytecodeLabel else_label, end_label;

  Visit(stmt->condition());
  builder()->CastAccumulatorToBoolean();
  builder()->JumpIfFalse(&else_label);
  Visit(stmt->then_statement());
  if (stmt->HasElseStatement()) {
    builder()->Jump(&end_label);
    builder()->Bind(&else_label);
    Visit(stmt->else_statement());
  } else {
    builder()->Bind(&else_label);
  }
  builder()->Bind(&end_label);
}


void BytecodeGenerator::VisitSloppyBlockFunctionStatement(
    SloppyBlockFunctionStatement* stmt) {
  Visit(stmt->statement());
}


void BytecodeGenerator::VisitContinueStatement(ContinueStatement* stmt) {
  control_scope()->Continue(stmt->target());
}


void BytecodeGenerator::VisitBreakStatement(BreakStatement* stmt) {
  control_scope()->Break(stmt->target());
}


void BytecodeGenerator::VisitReturnStatement(ReturnStatement* stmt) {
  Visit(stmt->expression());
  builder()->Return();
}


void BytecodeGenerator::VisitWithStatement(WithStatement* stmt) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitSwitchStatement(SwitchStatement* stmt) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitCaseClause(CaseClause* clause) { UNIMPLEMENTED(); }


void BytecodeGenerator::VisitDoWhileStatement(DoWhileStatement* stmt) {
  LoopBuilder loop_builder(builder());
  ControlScopeForIteration control_scope(this, stmt, &loop_builder);

  BytecodeLabel body_label, condition_label, done_label;
  builder()->Bind(&body_label);
  Visit(stmt->body());
  builder()->Bind(&condition_label);
  Visit(stmt->cond());
  builder()->JumpIfTrue(&body_label);
  builder()->Bind(&done_label);

  loop_builder.SetBreakTarget(done_label);
  loop_builder.SetContinueTarget(condition_label);
}


void BytecodeGenerator::VisitWhileStatement(WhileStatement* stmt) {
  LoopBuilder loop_builder(builder());
  ControlScopeForIteration control_scope(this, stmt, &loop_builder);

  BytecodeLabel body_label, condition_label, done_label;
  builder()->Jump(&condition_label);
  builder()->Bind(&body_label);
  Visit(stmt->body());
  builder()->Bind(&condition_label);
  Visit(stmt->cond());
  builder()->JumpIfTrue(&body_label);
  builder()->Bind(&done_label);

  loop_builder.SetBreakTarget(done_label);
  loop_builder.SetContinueTarget(condition_label);
}


void BytecodeGenerator::VisitForStatement(ForStatement* stmt) {
  LoopBuilder loop_builder(builder());
  ControlScopeForIteration control_scope(this, stmt, &loop_builder);

  if (stmt->init() != nullptr) {
    Visit(stmt->init());
  }

  BytecodeLabel body_label, condition_label, next_label, done_label;
  if (stmt->cond() != nullptr) {
    builder()->Jump(&condition_label);
  }
  builder()->Bind(&body_label);
  Visit(stmt->body());
  builder()->Bind(&next_label);
  if (stmt->next() != nullptr) {
    Visit(stmt->next());
  }
  if (stmt->cond()) {
    builder()->Bind(&condition_label);
    Visit(stmt->cond());
    builder()->JumpIfTrue(&body_label);
  } else {
    builder()->Jump(&body_label);
  }
  builder()->Bind(&done_label);

  loop_builder.SetBreakTarget(done_label);
  loop_builder.SetContinueTarget(next_label);
}


void BytecodeGenerator::VisitForInStatement(ForInStatement* stmt) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitForOfStatement(ForOfStatement* stmt) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitTryCatchStatement(TryCatchStatement* stmt) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitTryFinallyStatement(TryFinallyStatement* stmt) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitDebuggerStatement(DebuggerStatement* stmt) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitFunctionLiteral(FunctionLiteral* expr) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitClassLiteral(ClassLiteral* expr) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitNativeFunctionLiteral(
    NativeFunctionLiteral* expr) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitConditional(Conditional* expr) { UNIMPLEMENTED(); }


void BytecodeGenerator::VisitLiteral(Literal* expr) {
  Handle<Object> value = expr->value();
  if (value->IsSmi()) {
    builder()->LoadLiteral(Smi::cast(*value));
  } else if (value->IsUndefined()) {
    builder()->LoadUndefined();
  } else if (value->IsTrue()) {
    builder()->LoadTrue();
  } else if (value->IsFalse()) {
    builder()->LoadFalse();
  } else if (value->IsNull()) {
    builder()->LoadNull();
  } else if (value->IsTheHole()) {
    builder()->LoadTheHole();
  } else {
    builder()->LoadLiteral(value);
  }
}


void BytecodeGenerator::VisitRegExpLiteral(RegExpLiteral* expr) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitObjectLiteral(ObjectLiteral* expr) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitVariableProxy(VariableProxy* proxy) {
  VisitVariableLoad(proxy->var());
}


void BytecodeGenerator::VisitVariableLoad(Variable* variable) {
  switch (variable->location()) {
    case VariableLocation::LOCAL: {
      Register source(variable->index());
      builder()->LoadAccumulatorWithRegister(source);
      break;
    }
    case VariableLocation::PARAMETER: {
      // The parameter indices are shifted by 1 (receiver is variable
      // index -1 but is parameter index 0 in BytecodeArrayBuilder).
      Register source(builder()->Parameter(variable->index() + 1));
      builder()->LoadAccumulatorWithRegister(source);
      break;
    }
    case VariableLocation::GLOBAL: {
      // Global var, const, or let variable.
      // TODO(rmcilroy): If context chain depth is short enough, do this using
      // a generic version of LoadGlobalViaContextStub rather than calling the
      // runtime.
      DCHECK(variable->IsStaticGlobalObjectProperty());
      builder()->LoadGlobal(variable->index());
      break;
    }
    case VariableLocation::UNALLOCATED:
    case VariableLocation::CONTEXT:
    case VariableLocation::LOOKUP:
      UNIMPLEMENTED();
  }
}


void BytecodeGenerator::VisitAssignment(Assignment* expr) {
  DCHECK(expr->target()->IsValidReferenceExpression());
  TemporaryRegisterScope temporary_register_scope(&builder_);
  Register object, key;

  // Left-hand side can only be a property, a global or a variable slot.
  Property* property = expr->target()->AsProperty();
  LhsKind assign_type = Property::GetAssignType(property);

  // Evaluate LHS expression.
  switch (assign_type) {
    case VARIABLE:
      // Nothing to do to evaluate variable assignment LHS.
      break;
    case NAMED_PROPERTY:
      object = temporary_register_scope.NewRegister();
      key = temporary_register_scope.NewRegister();
      Visit(property->obj());
      builder()->StoreAccumulatorInRegister(object);
      builder()->LoadLiteral(property->key()->AsLiteral()->AsPropertyName());
      builder()->StoreAccumulatorInRegister(key);
      break;
    case KEYED_PROPERTY:
      object = temporary_register_scope.NewRegister();
      key = temporary_register_scope.NewRegister();
      Visit(property->obj());
      builder()->StoreAccumulatorInRegister(object);
      Visit(property->key());
      builder()->StoreAccumulatorInRegister(key);
      break;
    case NAMED_SUPER_PROPERTY:
    case KEYED_SUPER_PROPERTY:
      UNIMPLEMENTED();
  }

  // Evaluate the value and potentially handle compound assignments by loading
  // the left-hand side value and performing a binary operation.
  if (expr->is_compound()) {
    UNIMPLEMENTED();
  } else {
    Visit(expr->value());
  }

  // Store the value.
  FeedbackVectorSlot slot = expr->AssignmentSlot();
  switch (assign_type) {
    case VARIABLE: {
      Variable* variable = expr->target()->AsVariableProxy()->var();
      DCHECK(variable->location() == VariableLocation::LOCAL);
      Register destination(variable->index());
      builder()->StoreAccumulatorInRegister(destination);
      break;
    }
    case NAMED_PROPERTY:
      builder()->StoreNamedProperty(object, key, feedback_index(slot),
                                    language_mode());
      break;
    case KEYED_PROPERTY:
      builder()->StoreKeyedProperty(object, key, feedback_index(slot),
                                    language_mode());
      break;
    case NAMED_SUPER_PROPERTY:
    case KEYED_SUPER_PROPERTY:
      UNIMPLEMENTED();
  }
}


void BytecodeGenerator::VisitYield(Yield* expr) { UNIMPLEMENTED(); }


void BytecodeGenerator::VisitThrow(Throw* expr) { UNIMPLEMENTED(); }


void BytecodeGenerator::VisitPropertyLoad(Register obj, Property* expr) {
  LhsKind property_kind = Property::GetAssignType(expr);
  FeedbackVectorSlot slot = expr->PropertyFeedbackSlot();
  switch (property_kind) {
    case VARIABLE:
      UNREACHABLE();
    case NAMED_PROPERTY: {
      builder()->LoadLiteral(expr->key()->AsLiteral()->AsPropertyName());
      builder()->LoadNamedProperty(obj, feedback_index(slot), language_mode());
      break;
    }
    case KEYED_PROPERTY: {
      Visit(expr->key());
      builder()->LoadKeyedProperty(obj, feedback_index(slot), language_mode());
      break;
    }
    case NAMED_SUPER_PROPERTY:
    case KEYED_SUPER_PROPERTY:
      UNIMPLEMENTED();
  }
}


void BytecodeGenerator::VisitProperty(Property* expr) {
  TemporaryRegisterScope temporary_register_scope(&builder_);
  Register obj = temporary_register_scope.NewRegister();
  Visit(expr->obj());
  builder()->StoreAccumulatorInRegister(obj);
  VisitPropertyLoad(obj, expr);
}


void BytecodeGenerator::VisitCall(Call* expr) {
  Expression* callee_expr = expr->expression();
  Call::CallType call_type = expr->GetCallType(isolate());

  // Prepare the callee and the receiver to the function call. This depends on
  // the semantics of the underlying call type.
  TemporaryRegisterScope temporary_register_scope(&builder_);
  Register callee = temporary_register_scope.NewRegister();
  Register receiver = temporary_register_scope.NewRegister();

  switch (call_type) {
    case Call::PROPERTY_CALL: {
      Property* property = callee_expr->AsProperty();
      if (property->IsSuperAccess()) {
        UNIMPLEMENTED();
      }
      Visit(property->obj());
      builder()->StoreAccumulatorInRegister(receiver);
      // Perform a property load of the callee.
      VisitPropertyLoad(receiver, property);
      builder()->StoreAccumulatorInRegister(callee);
      break;
    }
    case Call::GLOBAL_CALL: {
      // Receiver is undefined for global calls.
      builder()->LoadUndefined().StoreAccumulatorInRegister(receiver);
      // Load callee as a global variable.
      VariableProxy* proxy = callee_expr->AsVariableProxy();
      VisitVariableLoad(proxy->var());
      builder()->StoreAccumulatorInRegister(callee);
      break;
    }
    case Call::LOOKUP_SLOT_CALL:
    case Call::SUPER_CALL:
    case Call::POSSIBLY_EVAL_CALL:
    case Call::OTHER_CALL:
      UNIMPLEMENTED();
  }

  // Evaluate all arguments to the function call and store in sequential
  // registers.
  ZoneList<Expression*>* args = expr->arguments();
  for (int i = 0; i < args->length(); ++i) {
    Visit(args->at(i));
    Register arg = temporary_register_scope.NewRegister();
    DCHECK(arg.index() - i == receiver.index() + 1);
    builder()->StoreAccumulatorInRegister(arg);
  }

  // TODO(rmcilroy): Deal with possible direct eval here?
  // TODO(rmcilroy): Use CallIC to allow call type feedback.
  builder()->Call(callee, receiver, args->length());
}


void BytecodeGenerator::VisitCallNew(CallNew* expr) { UNIMPLEMENTED(); }


void BytecodeGenerator::VisitCallRuntime(CallRuntime* expr) { UNIMPLEMENTED(); }


void BytecodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitCountOperation(CountOperation* expr) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitBinaryOperation(BinaryOperation* binop) {
  switch (binop->op()) {
    case Token::COMMA:
    case Token::OR:
    case Token::AND:
      UNIMPLEMENTED();
      break;
    default:
      VisitArithmeticExpression(binop);
      break;
  }
}


void BytecodeGenerator::VisitCompareOperation(CompareOperation* expr) {
  Token::Value op = expr->op();
  Expression* left = expr->left();
  Expression* right = expr->right();

  TemporaryRegisterScope temporary_register_scope(&builder_);
  Register temporary = temporary_register_scope.NewRegister();

  Visit(left);
  builder()->StoreAccumulatorInRegister(temporary);
  Visit(right);
  builder()->CompareOperation(op, temporary, language_mode());
}


void BytecodeGenerator::VisitSpread(Spread* expr) { UNREACHABLE(); }


void BytecodeGenerator::VisitEmptyParentheses(EmptyParentheses* expr) {
  UNREACHABLE();
}


void BytecodeGenerator::VisitThisFunction(ThisFunction* expr) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitSuperCallReference(SuperCallReference* expr) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitSuperPropertyReference(
    SuperPropertyReference* expr) {
  UNIMPLEMENTED();
}


void BytecodeGenerator::VisitArithmeticExpression(BinaryOperation* binop) {
  Token::Value op = binop->op();
  Expression* left = binop->left();
  Expression* right = binop->right();

  TemporaryRegisterScope temporary_register_scope(&builder_);
  Register temporary = temporary_register_scope.NewRegister();

  Visit(left);
  builder()->StoreAccumulatorInRegister(temporary);
  Visit(right);
  builder()->BinaryOperation(op, temporary);
}


LanguageMode BytecodeGenerator::language_mode() const {
  return info()->language_mode();
}


int BytecodeGenerator::feedback_index(FeedbackVectorSlot slot) const {
  return info()->feedback_vector()->GetIndex(slot);
}

}  // namespace interpreter
}  // namespace internal
}  // namespace v8