path: root/src/compiler/js-call-reducer.cc

// 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/compiler/js-call-reducer.h"

#include "src/compiler/js-graph.h"
#include "src/compiler/node-matchers.h"
#include "src/compiler/simplified-operator.h"
#include "src/objects-inl.h"
#include "src/type-feedback-vector-inl.h"

namespace v8 {
namespace internal {
namespace compiler {

Reduction JSCallReducer::Reduce(Node* node) {
  switch (node->opcode()) {
    case IrOpcode::kJSCallConstruct:
      return ReduceJSCallConstruct(node);
    case IrOpcode::kJSCallFunction:
      return ReduceJSCallFunction(node);
    default:
      break;
  }
  return NoChange();
}


// ES6 section 22.1.1 The Array Constructor
Reduction JSCallReducer::ReduceArrayConstructor(Node* node) {
  DCHECK_EQ(IrOpcode::kJSCallFunction, node->opcode());
  Node* target = NodeProperties::GetValueInput(node, 0);
  CallFunctionParameters const& p = CallFunctionParametersOf(node->op());

  // Check if we have an allocation site from the CallIC.
  Handle<AllocationSite> site;
  if (p.feedback().IsValid()) {
    CallICNexus nexus(p.feedback().vector(), p.feedback().slot());
    Handle<Object> feedback(nexus.GetFeedback(), isolate());
    if (feedback->IsAllocationSite()) {
      site = Handle<AllocationSite>::cast(feedback);
    }
  }

  // Turn the {node} into a {JSCreateArray} call.
  DCHECK_LE(2u, p.arity());
  size_t const arity = p.arity() - 2;
  NodeProperties::ReplaceValueInput(node, target, 0);
  NodeProperties::ReplaceValueInput(node, target, 1);
  // TODO(bmeurer): We might need to propagate the tail call mode to
  // the JSCreateArray operator, because an Array call in tail call
  // position must always properly consume the parent stack frame.
  NodeProperties::ChangeOp(node, javascript()->CreateArray(arity, site));
  return Changed(node);
}


// ES6 section 20.1.1 The Number Constructor
Reduction JSCallReducer::ReduceNumberConstructor(Node* node) {
  DCHECK_EQ(IrOpcode::kJSCallFunction, node->opcode());
  CallFunctionParameters const& p = CallFunctionParametersOf(node->op());

  // Turn the {node} into a {JSToNumber} call.
  DCHECK_LE(2u, p.arity());
  Node* value = (p.arity() == 2) ? jsgraph()->ZeroConstant()
                                 : NodeProperties::GetValueInput(node, 2);
  NodeProperties::ReplaceValueInputs(node, value);
  NodeProperties::ChangeOp(node, javascript()->ToNumber());
  return Changed(node);
}


// ES6 section 19.2.3.1 Function.prototype.apply ( thisArg, argArray )
Reduction JSCallReducer::ReduceFunctionPrototypeApply(Node* node) {
  DCHECK_EQ(IrOpcode::kJSCallFunction, node->opcode());
  Node* target = NodeProperties::GetValueInput(node, 0);
  CallFunctionParameters const& p = CallFunctionParametersOf(node->op());
  Handle<JSFunction> apply =
      Handle<JSFunction>::cast(HeapObjectMatcher(target).Value());
  size_t arity = p.arity();
  DCHECK_LE(2u, arity);
  ConvertReceiverMode convert_mode = ConvertReceiverMode::kAny;
  if (arity == 2) {
    // Neither thisArg nor argArray was provided.
    convert_mode = ConvertReceiverMode::kNullOrUndefined;
    node->ReplaceInput(0, node->InputAt(1));
    node->ReplaceInput(1, jsgraph()->UndefinedConstant());
  } else if (arity == 3) {
    // The argArray was not provided, just remove the {target}.
    node->RemoveInput(0);
    --arity;
  } else if (arity == 4) {
    // Check if argArray is an arguments object, and {node} is the only value
    // user of argArray (except for value uses in frame states).
    Node* arg_array = NodeProperties::GetValueInput(node, 3);
    if (arg_array->opcode() != IrOpcode::kJSCreateArguments) return NoChange();
    for (Edge edge : arg_array->use_edges()) {
      if (edge.from()->opcode() == IrOpcode::kStateValues) continue;
      if (!NodeProperties::IsValueEdge(edge)) continue;
      if (edge.from() == node) continue;
      return NoChange();
    }
    // Get to the actual frame state from which to extract the arguments;
    // we can only optimize this in case the {node} was already inlined into
    // some other function (and same for the {arg_array}).
    CreateArgumentsType type = CreateArgumentsTypeOf(arg_array->op());
    Node* frame_state = NodeProperties::GetFrameStateInput(arg_array);
    Node* outer_state = frame_state->InputAt(kFrameStateOuterStateInput);
    if (outer_state->opcode() != IrOpcode::kFrameState) return NoChange();
    FrameStateInfo outer_info = OpParameter<FrameStateInfo>(outer_state);
    if (outer_info.type() == FrameStateType::kArgumentsAdaptor) {
      // Need to take the parameters from the arguments adaptor.
      frame_state = outer_state;
    }
    FrameStateInfo state_info = OpParameter<FrameStateInfo>(frame_state);
    int start_index = 0;
    if (type == CreateArgumentsType::kMappedArguments) {
      // Mapped arguments (sloppy mode) cannot be handled if they are aliased.
      Handle<SharedFunctionInfo> shared;
      if (!state_info.shared_info().ToHandle(&shared)) return NoChange();
      if (shared->internal_formal_parameter_count() != 0) return NoChange();
    } else if (type == CreateArgumentsType::kRestParameter) {
      Handle<SharedFunctionInfo> shared;
      if (!state_info.shared_info().ToHandle(&shared)) return NoChange();
      start_index = shared->internal_formal_parameter_count();
    }
    // Remove the argArray input from the {node}.
    node->RemoveInput(static_cast<int>(--arity));
    // Add the actual parameters to the {node}, skipping the receiver.
    Node* const parameters = frame_state->InputAt(kFrameStateParametersInput);
    for (int i = start_index + 1; i < state_info.parameter_count(); ++i) {
      node->InsertInput(graph()->zone(), static_cast<int>(arity),
                        parameters->InputAt(i));
      ++arity;
    }
    // Drop the {target} from the {node}.
    node->RemoveInput(0);
    --arity;
  } else {
    return NoChange();
  }
  // Change {node} to the new {JSCallFunction} operator.
  NodeProperties::ChangeOp(
      node, javascript()->CallFunction(arity, p.frequency(), VectorSlotPair(),
                                       convert_mode, p.tail_call_mode()));
  // Change context of {node} to the Function.prototype.apply context,
  // to ensure any exception is thrown in the correct context.
  NodeProperties::ReplaceContextInput(
      node, jsgraph()->HeapConstant(handle(apply->context(), isolate())));
  // Try to further reduce the JSCallFunction {node}.
  Reduction const reduction = ReduceJSCallFunction(node);
  return reduction.Changed() ? reduction : Changed(node);
}


// ES6 section 19.2.3.3 Function.prototype.call (thisArg, ...args)
Reduction JSCallReducer::ReduceFunctionPrototypeCall(Node* node) {
  DCHECK_EQ(IrOpcode::kJSCallFunction, node->opcode());
  CallFunctionParameters const& p = CallFunctionParametersOf(node->op());
  Handle<JSFunction> call = Handle<JSFunction>::cast(
      HeapObjectMatcher(NodeProperties::GetValueInput(node, 0)).Value());
  // Change context of {node} to the Function.prototype.call context,
  // to ensure any exception is thrown in the correct context.
  NodeProperties::ReplaceContextInput(
      node, jsgraph()->HeapConstant(handle(call->context(), isolate())));
  // Remove the target from {node} and use the receiver as target instead, and
  // the thisArg becomes the new target.  If thisArg was not provided, insert
  // undefined instead.
  size_t arity = p.arity();
  DCHECK_LE(2u, arity);
  ConvertReceiverMode convert_mode;
  if (arity == 2) {
    // The thisArg was not provided, use undefined as receiver.
    convert_mode = ConvertReceiverMode::kNullOrUndefined;
    node->ReplaceInput(0, node->InputAt(1));
    node->ReplaceInput(1, jsgraph()->UndefinedConstant());
  } else {
    // Just remove the target, which is the first value input.
    convert_mode = ConvertReceiverMode::kAny;
    node->RemoveInput(0);
    --arity;
  }
  NodeProperties::ChangeOp(
      node, javascript()->CallFunction(arity, p.frequency(), VectorSlotPair(),
                                       convert_mode, p.tail_call_mode()));
  // Try to further reduce the JSCallFunction {node}.
  Reduction const reduction = ReduceJSCallFunction(node);
  return reduction.Changed() ? reduction : Changed(node);
}

namespace {

// TODO(turbofan): Shall we move this to the NodeProperties? Or some (untyped)
// alias analyzer?
bool IsSame(Node* a, Node* b) {
  if (a == b) {
    return true;
  } else if (a->opcode() == IrOpcode::kCheckHeapObject) {
    return IsSame(a->InputAt(0), b);
  } else if (b->opcode() == IrOpcode::kCheckHeapObject) {
    return IsSame(a, b->InputAt(0));
  }
  return false;
}

// TODO(turbofan): Share with similar functionality in JSInliningHeuristic
// and JSNativeContextSpecialization, i.e. move to NodeProperties helper?!
MaybeHandle<Map> InferReceiverMap(Node* node) {
  Node* receiver = NodeProperties::GetValueInput(node, 1);
  Node* effect = NodeProperties::GetEffectInput(node);
  // Check if the {node} is dominated by a CheckMaps with a single map
  // for the {receiver}, and if so use that map for the lowering below.
  for (Node* dominator = effect;;) {
    if (dominator->opcode() == IrOpcode::kCheckMaps &&
        IsSame(dominator->InputAt(0), receiver)) {
      if (dominator->op()->ValueInputCount() == 2) {
        HeapObjectMatcher m(dominator->InputAt(1));
        if (m.HasValue()) return Handle<Map>::cast(m.Value());
      }
      return MaybeHandle<Map>();
    }
    if (dominator->op()->EffectInputCount() != 1) {
      // Didn't find any appropriate CheckMaps node.
      return MaybeHandle<Map>();
    }
    dominator = NodeProperties::GetEffectInput(dominator);
  }
}

}  // namespace

// ES6 section B.2.2.1.1 get Object.prototype.__proto__
Reduction JSCallReducer::ReduceObjectPrototypeGetProto(Node* node) {
  DCHECK_EQ(IrOpcode::kJSCallFunction, node->opcode());

  // Try to determine the {receiver} map.
  Handle<Map> receiver_map;
  if (InferReceiverMap(node).ToHandle(&receiver_map)) {
    // Check if we can constant-fold the {receiver} map.
    if (!receiver_map->IsJSProxyMap() &&
        !receiver_map->has_hidden_prototype() &&
        !receiver_map->is_access_check_needed()) {
      Handle<Object> receiver_prototype(receiver_map->prototype(), isolate());
      Node* value = jsgraph()->Constant(receiver_prototype);
      ReplaceWithValue(node, value);
      return Replace(value);
    }
  }

  return NoChange();
}

Reduction JSCallReducer::ReduceJSCallFunction(Node* node) {
  DCHECK_EQ(IrOpcode::kJSCallFunction, node->opcode());
  CallFunctionParameters const& p = CallFunctionParametersOf(node->op());
  Node* target = NodeProperties::GetValueInput(node, 0);
  Node* control = NodeProperties::GetControlInput(node);
  Node* effect = NodeProperties::GetEffectInput(node);

  // Try to specialize JSCallFunction {node}s with constant {target}s.
  HeapObjectMatcher m(target);
  if (m.HasValue()) {
    if (m.Value()->IsJSFunction()) {
      Handle<JSFunction> function = Handle<JSFunction>::cast(m.Value());
      Handle<SharedFunctionInfo> shared(function->shared(), isolate());

      // Raise a TypeError if the {target} is a "classConstructor".
      if (IsClassConstructor(shared->kind())) {
        NodeProperties::ReplaceValueInputs(node, target);
        NodeProperties::ChangeOp(
            node, javascript()->CallRuntime(
                      Runtime::kThrowConstructorNonCallableError, 1));
        return Changed(node);
      }

      // Check for known builtin functions.
      switch (shared->code()->builtin_index()) {
        case Builtins::kFunctionPrototypeApply:
          return ReduceFunctionPrototypeApply(node);
        case Builtins::kFunctionPrototypeCall:
          return ReduceFunctionPrototypeCall(node);
        case Builtins::kNumberConstructor:
          return ReduceNumberConstructor(node);
        case Builtins::kObjectPrototypeGetProto:
          return ReduceObjectPrototypeGetProto(node);
        default:
          break;
      }

      // Check for the Array constructor.
      if (*function == function->native_context()->array_function()) {
        return ReduceArrayConstructor(node);
      }
    } else if (m.Value()->IsJSBoundFunction()) {
      Handle<JSBoundFunction> function =
          Handle<JSBoundFunction>::cast(m.Value());
      Handle<JSReceiver> bound_target_function(
          function->bound_target_function(), isolate());
      Handle<Object> bound_this(function->bound_this(), isolate());
      Handle<FixedArray> bound_arguments(function->bound_arguments(),
                                         isolate());
      CallFunctionParameters const& p = CallFunctionParametersOf(node->op());
      ConvertReceiverMode const convert_mode =
          (bound_this->IsNull(isolate()) || bound_this->IsUndefined(isolate()))
              ? ConvertReceiverMode::kNullOrUndefined
              : ConvertReceiverMode::kNotNullOrUndefined;
      size_t arity = p.arity();
      DCHECK_LE(2u, arity);
      // Patch {node} to use [[BoundTargetFunction]] and [[BoundThis]].
      NodeProperties::ReplaceValueInput(
          node, jsgraph()->Constant(bound_target_function), 0);
      NodeProperties::ReplaceValueInput(node, jsgraph()->Constant(bound_this),
                                        1);
      // Insert the [[BoundArguments]] for {node}.
      for (int i = 0; i < bound_arguments->length(); ++i) {
        node->InsertInput(
            graph()->zone(), i + 2,
            jsgraph()->Constant(handle(bound_arguments->get(i), isolate())));
        arity++;
      }
      NodeProperties::ChangeOp(node, javascript()->CallFunction(
                                         arity, p.frequency(), VectorSlotPair(),
                                         convert_mode, p.tail_call_mode()));
      // Try to further reduce the JSCallFunction {node}.
      Reduction const reduction = ReduceJSCallFunction(node);
      return reduction.Changed() ? reduction : Changed(node);
    }

    // Don't mess with other {node}s that have a constant {target}.
    // TODO(bmeurer): Also support proxies here.
    return NoChange();
  }

  // Not much we can do if deoptimization support is disabled.
  if (!(flags() & kDeoptimizationEnabled)) return NoChange();

  // Extract feedback from the {node} using the CallICNexus.
  if (!p.feedback().IsValid()) return NoChange();
  CallICNexus nexus(p.feedback().vector(), p.feedback().slot());
  if (nexus.IsUninitialized() && (flags() & kBailoutOnUninitialized)) {
    Node* frame_state = NodeProperties::FindFrameStateBefore(node);
    Node* deoptimize = graph()->NewNode(
        common()->Deoptimize(
            DeoptimizeKind::kSoft,
            DeoptimizeReason::kInsufficientTypeFeedbackForCall),
        frame_state, effect, control);
    // TODO(bmeurer): This should be on the AdvancedReducer somehow.
    NodeProperties::MergeControlToEnd(graph(), common(), deoptimize);
    Revisit(graph()->end());
    node->TrimInputCount(0);
    NodeProperties::ChangeOp(node, common()->Dead());
    return Changed(node);
  }
  Handle<Object> feedback(nexus.GetFeedback(), isolate());
  if (feedback->IsAllocationSite()) {
    // Retrieve the Array function from the {node}.
    Node* array_function = jsgraph()->HeapConstant(
        handle(native_context()->array_function(), isolate()));

    // Check that the {target} is still the {array_function}.
    Node* check = graph()->NewNode(simplified()->ReferenceEqual(), target,
                                   array_function);
    effect = graph()->NewNode(simplified()->CheckIf(), check, effect, control);

    // Turn the {node} into a {JSCreateArray} call.
    NodeProperties::ReplaceValueInput(node, array_function, 0);
    NodeProperties::ReplaceEffectInput(node, effect);
    return ReduceArrayConstructor(node);
  } else if (feedback->IsWeakCell()) {
    Handle<WeakCell> cell = Handle<WeakCell>::cast(feedback);
    if (cell->value()->IsJSFunction()) {
      Node* target_function =
          jsgraph()->Constant(handle(cell->value(), isolate()));

      // Check that the {target} is still the {target_function}.
      Node* check = graph()->NewNode(simplified()->ReferenceEqual(), target,
                                     target_function);
      effect =
          graph()->NewNode(simplified()->CheckIf(), check, effect, control);

      // Specialize the JSCallFunction node to the {target_function}.
      NodeProperties::ReplaceValueInput(node, target_function, 0);
      NodeProperties::ReplaceEffectInput(node, effect);

      // Try to further reduce the JSCallFunction {node}.
      Reduction const reduction = ReduceJSCallFunction(node);
      return reduction.Changed() ? reduction : Changed(node);
    }
  }
  return NoChange();
}


Reduction JSCallReducer::ReduceJSCallConstruct(Node* node) {
  DCHECK_EQ(IrOpcode::kJSCallConstruct, node->opcode());
  CallConstructParameters const& p = CallConstructParametersOf(node->op());
  DCHECK_LE(2u, p.arity());
  int const arity = static_cast<int>(p.arity() - 2);
  Node* target = NodeProperties::GetValueInput(node, 0);
  Node* new_target = NodeProperties::GetValueInput(node, arity + 1);
  Node* effect = NodeProperties::GetEffectInput(node);
  Node* control = NodeProperties::GetControlInput(node);

  // Try to specialize JSCallConstruct {node}s with constant {target}s.
  HeapObjectMatcher m(target);
  if (m.HasValue()) {
    if (m.Value()->IsJSFunction()) {
      Handle<JSFunction> function = Handle<JSFunction>::cast(m.Value());

      // Raise a TypeError if the {target} is not a constructor.
      if (!function->IsConstructor()) {
        NodeProperties::ReplaceValueInputs(node, target);
        NodeProperties::ChangeOp(
            node, javascript()->CallRuntime(Runtime::kThrowCalledNonCallable));
        return Changed(node);
      }

      // Check for the ArrayConstructor.
      if (*function == function->native_context()->array_function()) {
        // Check if we have an allocation site.
        Handle<AllocationSite> site;
        if (p.feedback().IsValid()) {
          CallICNexus nexus(p.feedback().vector(), p.feedback().slot());
          Handle<Object> feedback(nexus.GetFeedback(), isolate());
          if (feedback->IsAllocationSite()) {
            site = Handle<AllocationSite>::cast(feedback);
          }
        }

        // Turn the {node} into a {JSCreateArray} call.
        for (int i = arity; i > 0; --i) {
          NodeProperties::ReplaceValueInput(
              node, NodeProperties::GetValueInput(node, i), i + 1);
        }
        NodeProperties::ReplaceValueInput(node, new_target, 1);
        NodeProperties::ChangeOp(node, javascript()->CreateArray(arity, site));
        return Changed(node);
      }
    }

    // Don't mess with other {node}s that have a constant {target}.
    // TODO(bmeurer): Also support optimizing bound functions and proxies here.
    return NoChange();
  }

  // Not much we can do if deoptimization support is disabled.
  if (!(flags() & kDeoptimizationEnabled)) return NoChange();

  if (!p.feedback().IsValid()) return NoChange();
  CallICNexus nexus(p.feedback().vector(), p.feedback().slot());
  Handle<Object> feedback(nexus.GetFeedback(), isolate());
  if (feedback->IsAllocationSite()) {
    // The feedback is an AllocationSite, which means we have called the
    // Array function and collected transition (and pretenuring) feedback
    // for the resulting arrays.  This has to be kept in sync with the
    // implementation of the CallConstructStub.
    Handle<AllocationSite> site = Handle<AllocationSite>::cast(feedback);

    // Retrieve the Array function from the {node}.
    Node* array_function = jsgraph()->HeapConstant(
        handle(native_context()->array_function(), isolate()));

    // Check that the {target} is still the {array_function}.
    Node* check = graph()->NewNode(simplified()->ReferenceEqual(), target,
                                   array_function);
    effect = graph()->NewNode(simplified()->CheckIf(), check, effect, control);

    // Turn the {node} into a {JSCreateArray} call.
    NodeProperties::ReplaceEffectInput(node, effect);
    for (int i = arity; i > 0; --i) {
      NodeProperties::ReplaceValueInput(
          node, NodeProperties::GetValueInput(node, i), i + 1);
    }
    NodeProperties::ReplaceValueInput(node, new_target, 1);
    NodeProperties::ChangeOp(node, javascript()->CreateArray(arity, site));
    return Changed(node);
  } else if (feedback->IsWeakCell()) {
    Handle<WeakCell> cell = Handle<WeakCell>::cast(feedback);
    if (cell->value()->IsJSFunction()) {
      Node* target_function =
          jsgraph()->Constant(handle(cell->value(), isolate()));

      // Check that the {target} is still the {target_function}.
      Node* check = graph()->NewNode(simplified()->ReferenceEqual(), target,
                                     target_function);
      effect =
          graph()->NewNode(simplified()->CheckIf(), check, effect, control);

      // Specialize the JSCallConstruct node to the {target_function}.
      NodeProperties::ReplaceValueInput(node, target_function, 0);
      NodeProperties::ReplaceEffectInput(node, effect);
      if (target == new_target) {
        NodeProperties::ReplaceValueInput(node, target_function, arity + 1);
      }

      // Try to further reduce the JSCallConstruct {node}.
      Reduction const reduction = ReduceJSCallConstruct(node);
      return reduction.Changed() ? reduction : Changed(node);
    }
  }

  return NoChange();
}

Graph* JSCallReducer::graph() const { return jsgraph()->graph(); }

Isolate* JSCallReducer::isolate() const { return jsgraph()->isolate(); }

CommonOperatorBuilder* JSCallReducer::common() const {
  return jsgraph()->common();
}

JSOperatorBuilder* JSCallReducer::javascript() const {
  return jsgraph()->javascript();
}

SimplifiedOperatorBuilder* JSCallReducer::simplified() const {
  return jsgraph()->simplified();
}

}  // namespace compiler
}  // namespace internal
}  // namespace v8