text: // Copyright 2014 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/simplified-operator-reducer.h"
  
  #include "src/compiler/js-graph.h"
  #include "src/compiler/machine-operator.h"
  #include "src/compiler/node-matchers.h"
  #include "src/compiler/operator-properties.h"
  #include "src/compiler/simplified-operator.h"
  #include "src/compiler/type-cache.h"
  #include "src/numbers/conversions-inl.h"
  
  namespace v8 {
  namespace internal {
  namespace compiler {
  
  namespace {
  
  Decision DecideObjectIsSmi(Node* const input) {
    NumberMatcher m(input);
    if (m.HasResolvedValue()) {
      return IsSmiDouble(m.ResolvedValue()) ? Decision::kTrue : Decision::kFalse;
    }
    if (m.IsAllocate()) return Decision::kFalse;
    if (m.IsChangeBitToTagged()) return Decision::kFalse;
    if (m.IsChangeInt31ToTaggedSigned()) return Decision::kTrue;
    if (m.IsHeapConstant()) return Decision::kFalse;
    return Decision::kUnknown;
  }
  
  }  // namespace
  
  SimplifiedOperatorReducer::SimplifiedOperatorReducer(Editor* editor,
                                                       JSGraph* jsgraph,
                                                       JSHeapBroker* broker)
      : AdvancedReducer(editor), jsgraph_(jsgraph), broker_(broker) {}
  
  SimplifiedOperatorReducer::~SimplifiedOperatorReducer() = default;
  
  
  Reduction SimplifiedOperatorReducer::Reduce(Node* node) {
    DisallowHeapAccess no_heap_access;
    switch (node->opcode()) {
      case IrOpcode::kBooleanNot: {
        HeapObjectMatcher m(node->InputAt(0));
        if (m.Is(factory()->true_value())) return ReplaceBoolean(false);
        if (m.Is(factory()->false_value())) return ReplaceBoolean(true);
        if (m.IsBooleanNot()) return Replace(m.InputAt(0));
        break;
      }
      case IrOpcode::kChangeBitToTagged: {
        Int32Matcher m(node->InputAt(0));
        if (m.Is(0)) return Replace(jsgraph()->FalseConstant());
        if (m.Is(1)) return Replace(jsgraph()->TrueConstant());
        if (m.IsChangeTaggedToBit()) return Replace(m.InputAt(0));
        break;
      }
      case IrOpcode::kChangeTaggedToBit: {
        HeapObjectMatcher m(node->InputAt(0));
        if (m.HasResolvedValue()) {
          return ReplaceInt32(m.Ref(broker()).BooleanValue());
        }
        if (m.IsChangeBitToTagged()) return Replace(m.InputAt(0));
        break;
      }
      case IrOpcode::kChangeFloat64ToTagged: {
        Float64Matcher m(node->InputAt(0));
        if (m.HasResolvedValue()) return ReplaceNumber(m.ResolvedValue());
        if (m.IsChangeTaggedToFloat64()) return Replace(m.node()->InputAt(0));
        break;
      }
      case IrOpcode::kChangeInt31ToTaggedSigned:
      case IrOpcode::kChangeInt32ToTagged: {
        Int32Matcher m(node->InputAt(0));
        if (m.HasResolvedValue()) return ReplaceNumber(m.ResolvedValue());
        if (m.IsChangeTaggedToInt32() || m.IsChangeTaggedSignedToInt32()) {
          return Replace(m.InputAt(0));
        }
        break;
      }
      case IrOpcode::kChangeTaggedToFloat64:
      case IrOpcode::kTruncateTaggedToFloat64: {
        NumberMatcher m(node->InputAt(0));
        if (m.HasResolvedValue()) return ReplaceFloat64(m.ResolvedValue());
        if (m.IsChangeFloat64ToTagged() || m.IsChangeFloat64ToTaggedPointer()) {
          return Replace(m.node()->InputAt(0));
        }
        if (m.IsChangeInt31ToTaggedSigned() || m.IsChangeInt32ToTagged()) {
          return Change(node, machine()->ChangeInt32ToFloat64(), m.InputAt(0));
        }
        if (m.IsChangeUint32ToTagged()) {
          return Change(node, machine()->ChangeUint32ToFloat64(), m.InputAt(0));
        }
        break;
      }
      case IrOpcode::kChangeTaggedSignedToInt32:
      case IrOpcode::kChangeTaggedToInt32: {
        NumberMatcher m(node->InputAt(0));
        if (m.HasResolvedValue())
          return ReplaceInt32(DoubleToInt32(m.ResolvedValue()));
        if (m.IsChangeFloat64ToTagged() || m.IsChangeFloat64ToTaggedPointer()) {
          return Change(node, machine()->ChangeFloat64ToInt32(), m.InputAt(0));
        }
        if (m.IsChangeInt31ToTaggedSigned() || m.IsChangeInt32ToTagged()) {
          return Replace(m.InputAt(0));
        }
        break;
      }
      case IrOpcode::kChangeTaggedToUint32: {
        NumberMatcher m(node->InputAt(0));
        if (m.HasResolvedValue())
          return ReplaceUint32(DoubleToUint32(m.ResolvedValue()));
        if (m.IsChangeFloat64ToTagged() || m.IsChangeFloat64ToTaggedPointer()) {
          return Change(node, machine()->ChangeFloat64ToUint32(), m.InputAt(0));
        }
        if (m.IsChangeUint32ToTagged()) return Replace(m.InputAt(0));
        break;
      }
      case IrOpcode::kChangeUint32ToTagged: {
        Uint32Matcher m(node->InputAt(0));
        if (m.HasResolvedValue())
          return ReplaceNumber(FastUI2D(m.ResolvedValue()));
        break;
      }
      case IrOpcode::kTruncateTaggedToWord32: {
        NumberMatcher m(node->InputAt(0));
        if (m.HasResolvedValue())
          return ReplaceInt32(DoubleToInt32(m.ResolvedValue()));
        if (m.IsChangeInt31ToTaggedSigned() || m.IsChangeInt32ToTagged() ||
            m.IsChangeUint32ToTagged()) {
          return Replace(m.InputAt(0));
        }
        if (m.IsChangeFloat64ToTagged() || m.IsChangeFloat64ToTaggedPointer()) {
          return Change(node, machine()->TruncateFloat64ToWord32(), m.InputAt(0));
        }
        break;
      }
      case IrOpcode::kCheckedFloat64ToInt32: {
        Float64Matcher m(node->InputAt(0));
        if (m.HasResolvedValue() && IsInt32Double(m.ResolvedValue())) {
          Node* value =
              jsgraph()->Int32Constant(static_cast<int32_t>(m.ResolvedValue()));
          ReplaceWithValue(node, value);
          return Replace(value);
        }
        break;
      }
      case IrOpcode::kCheckedTaggedToArrayIndex:
      case IrOpcode::kCheckedTaggedToInt32:
      case IrOpcode::kCheckedTaggedSignedToInt32: {
        NodeMatcher m(node->InputAt(0));
        if (m.IsConvertTaggedHoleToUndefined()) {
          node->ReplaceInput(0, m.InputAt(0));
          return Changed(node);
        }
        break;
      }
      case IrOpcode::kCheckIf: {
        HeapObjectMatcher m(node->InputAt(0));
        if (m.Is(factory()->true_value())) {
          Node* const effect = NodeProperties::GetEffectInput(node);
          return Replace(effect);
        }
        break;
      }
      case IrOpcode::kCheckNumber: {
        NodeMatcher m(node->InputAt(0));
        if (m.IsConvertTaggedHoleToUndefined()) {
          node->ReplaceInput(0, m.InputAt(0));
          return Changed(node);
        }
        break;
      }
      case IrOpcode::kCheckHeapObject: {
        Node* const input = node->InputAt(0);
        if (DecideObjectIsSmi(input) == Decision::kFalse) {
          ReplaceWithValue(node, input);
          return Replace(input);
        }
        NodeMatcher m(input);
        if (m.IsCheckHeapObject()) {
          ReplaceWithValue(node, input);
          return Replace(input);
        }
        break;
      }
      case IrOpcode::kCheckSmi: {
        Node* const input = node->InputAt(0);
        if (DecideObjectIsSmi(input) == Decision::kTrue) {
          ReplaceWithValue(node, input);
          return Replace(input);
        }
        NodeMatcher m(input);
        if (m.IsCheckSmi()) {
          ReplaceWithValue(node, input);
          return Replace(input);
        } else if (m.IsConvertTaggedHoleToUndefined()) {
          node->ReplaceInput(0, m.InputAt(0));
          return Changed(node);
        }
        break;
      }
      case IrOpcode::kObjectIsSmi: {
        Node* const input = node->InputAt(0);
        switch (DecideObjectIsSmi(input)) {
          case Decision::kTrue:
            return ReplaceBoolean(true);
          case Decision::kFalse:
            return ReplaceBoolean(false);
          case Decision::kUnknown:
            break;
        }
        break;
      }
      case IrOpcode::kNumberAbs: {
        NumberMatcher m(node->InputAt(0));
        if (m.HasResolvedValue())
          return ReplaceNumber(std::fabs(m.ResolvedValue()));
        break;
      }
      case IrOpcode::kReferenceEqual: {
        HeapObjectBinopMatcher m(node);
        if (m.left().node() == m.right().node()) return ReplaceBoolean(true);
        break;
      }
      case IrOpcode::kCheckedInt32Add: {
        // (x + a) + b => x + (a + b) where a and b are constants and have the
        // same sign.
        Int32BinopMatcher m(node);
        if (m.right().HasResolvedValue()) {
          Node* checked_int32_add = m.left().node();
          if (checked_int32_add->opcode() == IrOpcode::kCheckedInt32Add) {
            Int32BinopMatcher n(checked_int32_add);
            if (n.right().HasResolvedValue() &&
                (n.right().ResolvedValue() >= 0) ==
                    (m.right().ResolvedValue() >= 0)) {
              int32_t val;
              bool overflow = base::bits::SignedAddOverflow32(
                  n.right().ResolvedValue(), m.right().ResolvedValue(), &val);
              if (!overflow) {
                bool has_no_other_uses = true;
                for (Edge edge : checked_int32_add->use_edges()) {
                  if (!edge.from()->IsDead() && edge.from() != node) {
                    has_no_other_uses = false;
                    break;
                  }
                }
                if (has_no_other_uses) {
                  node->ReplaceInput(0, n.left().node());
                  node->ReplaceInput(1, jsgraph()->Int32Constant(val));
                  RelaxEffectsAndControls(checked_int32_add);
                  return Changed(node);
                }
              }
            }
          }
        }
        break;
      }
      default:
        break;
    }
    return NoChange();
  }
  
  Reduction SimplifiedOperatorReducer::Change(Node* node, const Operator* op,
                                              Node* a) {
    DCHECK_EQ(node->InputCount(), OperatorProperties::GetTotalInputCount(op));
    DCHECK_LE(1, node->InputCount());
    node->ReplaceInput(0, a);
    NodeProperties::ChangeOp(node, op);
    return Changed(node);
  }
  
  Reduction SimplifiedOperatorReducer::ReplaceBoolean(bool value) {
    return Replace(jsgraph()->BooleanConstant(value));
  }
  
  Reduction SimplifiedOperatorReducer::ReplaceFloat64(double value) {
    return Replace(jsgraph()->Float64Constant(value));
  }
  
  
  Reduction SimplifiedOperatorReducer::ReplaceInt32(int32_t value) {
    return Replace(jsgraph()->Int32Constant(value));
  }
  
  
  Reduction SimplifiedOperatorReducer::ReplaceNumber(double value) {
    return Replace(jsgraph()->Constant(value));
  }
  
  
  Reduction SimplifiedOperatorReducer::ReplaceNumber(int32_t value) {
    return Replace(jsgraph()->Constant(value));
  }
  
  Factory* SimplifiedOperatorReducer::factory() const {
    return jsgraph()->isolate()->factory();
  }
  
  Graph* SimplifiedOperatorReducer::graph() const { return jsgraph()->graph(); }
  
  MachineOperatorBuilder* SimplifiedOperatorReducer::machine() const {
    return jsgraph()->machine();
  }
  
  SimplifiedOperatorBuilder* SimplifiedOperatorReducer::simplified() const {
    return jsgraph()->simplified();
  }
  
  }  // namespace compiler
  }  // namespace internal
  }  // namespace v8
  