src/compiler/verifier.cc

// 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/verifier.h"

#include <algorithm>
#include <deque>
#include <queue>
#include <sstream>
#include <string>

#include "src/bit-vector.h"
#include "src/compiler/all-nodes.h"
#include "src/compiler/common-operator.h"
#include "src/compiler/graph.h"
#include "src/compiler/node.h"
#include "src/compiler/node-properties.h"
#include "src/compiler/opcodes.h"
#include "src/compiler/operator.h"
#include "src/compiler/operator-properties.h"
#include "src/compiler/schedule.h"
#include "src/compiler/simplified-operator.h"
#include "src/ostreams.h"

namespace v8 {
namespace internal {
namespace compiler {


static bool IsDefUseChainLinkPresent(Node* def, Node* use) {
  const Node::Uses uses = def->uses();
  return std::find(uses.begin(), uses.end(), use) != uses.end();
}


static bool IsUseDefChainLinkPresent(Node* def, Node* use) {
  const Node::Inputs inputs = use->inputs();
  return std::find(inputs.begin(), inputs.end(), def) != inputs.end();
}


class Verifier::Visitor {
 public:
  Visitor(Zone* z, Typing typed) : zone(z), typing(typed) {}

  void Check(Node* node);

  Zone* zone;
  Typing typing;

 private:
  void CheckNotTyped(Node* node) {
    if (NodeProperties::IsTyped(node)) {
      std::ostringstream str;
      str << "TypeError: node #" << node->id() << ":" << *node->op()
          << " should never have a type";
      FATAL(str.str().c_str());
    }
  }
  void CheckUpperIs(Node* node, Type* type) {
    if (typing == TYPED && !NodeProperties::GetType(node)->Is(type)) {
      std::ostringstream str;
      str << "TypeError: node #" << node->id() << ":" << *node->op()
          << " type ";
      NodeProperties::GetType(node)->PrintTo(str);
      str << " is not ";
      type->PrintTo(str);
      FATAL(str.str().c_str());
    }
  }
  void CheckUpperMaybe(Node* node, Type* type) {
    if (typing == TYPED && !NodeProperties::GetType(node)->Maybe(type)) {
      std::ostringstream str;
      str << "TypeError: node #" << node->id() << ":" << *node->op()
          << " type ";
      NodeProperties::GetType(node)->PrintTo(str);
      str << " must intersect ";
      type->PrintTo(str);
      FATAL(str.str().c_str());
    }
  }
  void CheckValueInputIs(Node* node, int i, Type* type) {
    Node* input = NodeProperties::GetValueInput(node, i);
    if (typing == TYPED && !NodeProperties::GetType(input)->Is(type)) {
      std::ostringstream str;
      str << "TypeError: node #" << node->id() << ":" << *node->op()
          << "(input @" << i << " = " << input->opcode() << ":"
          << input->op()->mnemonic() << ") type ";
      NodeProperties::GetType(input)->PrintTo(str);
      str << " is not ";
      type->PrintTo(str);
      FATAL(str.str().c_str());
    }
  }
  void CheckOutput(Node* node, Node* use, int count, const char* kind) {
    if (count <= 0) {
      std::ostringstream str;
      str << "GraphError: node #" << node->id() << ":" << *node->op()
          << " does not produce " << kind << " output used by node #"
          << use->id() << ":" << *use->op();
      FATAL(str.str().c_str());
    }
  }
};


void Verifier::Visitor::Check(Node* node) {
  int value_count = node->op()->ValueInputCount();
  int context_count = OperatorProperties::GetContextInputCount(node->op());
  int frame_state_count =
      OperatorProperties::GetFrameStateInputCount(node->op());
  int effect_count = node->op()->EffectInputCount();
  int control_count = node->op()->ControlInputCount();

  // Verify number of inputs matches up.
  int input_count = value_count + context_count + frame_state_count +
                    effect_count + control_count;
  CHECK_EQ(input_count, node->InputCount());

  // Verify that frame state has been inserted for the nodes that need it.
  for (int i = 0; i < frame_state_count; i++) {
    Node* frame_state = NodeProperties::GetFrameStateInput(node, i);
    CHECK(frame_state->opcode() == IrOpcode::kFrameState ||
          // kFrameState uses Start as a sentinel.
          (node->opcode() == IrOpcode::kFrameState &&
           frame_state->opcode() == IrOpcode::kStart));
    CHECK(IsDefUseChainLinkPresent(frame_state, node));
    CHECK(IsUseDefChainLinkPresent(frame_state, node));
  }

  // Verify all value inputs actually produce a value.
  for (int i = 0; i < value_count; ++i) {
    Node* value = NodeProperties::GetValueInput(node, i);
    CheckOutput(value, node, value->op()->ValueOutputCount(), "value");
    CHECK(IsDefUseChainLinkPresent(value, node));
    CHECK(IsUseDefChainLinkPresent(value, node));
    // Verify that only parameters and projections can have input nodes with
    // multiple outputs.
    CHECK(node->opcode() == IrOpcode::kParameter ||
          node->opcode() == IrOpcode::kProjection ||
          value->op()->ValueOutputCount() <= 1);
  }

  // Verify all context inputs are value nodes.
  for (int i = 0; i < context_count; ++i) {
    Node* context = NodeProperties::GetContextInput(node);
    CheckOutput(context, node, context->op()->ValueOutputCount(), "context");
    CHECK(IsDefUseChainLinkPresent(context, node));
    CHECK(IsUseDefChainLinkPresent(context, node));
  }

  // Verify all effect inputs actually have an effect.
  for (int i = 0; i < effect_count; ++i) {
    Node* effect = NodeProperties::GetEffectInput(node);
    CheckOutput(effect, node, effect->op()->EffectOutputCount(), "effect");
    CHECK(IsDefUseChainLinkPresent(effect, node));
    CHECK(IsUseDefChainLinkPresent(effect, node));
  }

  // Verify all control inputs are control nodes.
  for (int i = 0; i < control_count; ++i) {
    Node* control = NodeProperties::GetControlInput(node, i);
    CheckOutput(control, node, control->op()->ControlOutputCount(), "control");
    CHECK(IsDefUseChainLinkPresent(control, node));
    CHECK(IsUseDefChainLinkPresent(control, node));
  }

  switch (node->opcode()) {
    case IrOpcode::kStart:
      // Start has no inputs.
      CHECK_EQ(0, input_count);
      // Type is a tuple.
      // TODO(rossberg): Multiple outputs are currently typed as Internal.
      CheckUpperIs(node, Type::Internal());
      break;
    case IrOpcode::kEnd:
      // End has no outputs.
      CHECK(node->op()->ValueOutputCount() == 0);
      CHECK(node->op()->EffectOutputCount() == 0);
      CHECK(node->op()->ControlOutputCount() == 0);
      // Type is empty.
      CheckNotTyped(node);
      break;
    case IrOpcode::kDead:
      // Dead is never connected to the graph.
      UNREACHABLE();
      break;
    case IrOpcode::kBranch: {
      // Branch uses are IfTrue and IfFalse.
      int count_true = 0, count_false = 0;
      for (const Node* use : node->uses()) {
        CHECK(use->opcode() == IrOpcode::kIfTrue ||
              use->opcode() == IrOpcode::kIfFalse);
        if (use->opcode() == IrOpcode::kIfTrue) ++count_true;
        if (use->opcode() == IrOpcode::kIfFalse) ++count_false;
      }
      CHECK_EQ(1, count_true);
      CHECK_EQ(1, count_false);
      // Type is empty.
      CheckNotTyped(node);
      break;
    }
    case IrOpcode::kIfTrue:
    case IrOpcode::kIfFalse:
      CHECK_EQ(IrOpcode::kBranch,
               NodeProperties::GetControlInput(node, 0)->opcode());
      // Type is empty.
      CheckNotTyped(node);
      break;
    case IrOpcode::kIfSuccess: {
      // IfSuccess and IfException continuation only on throwing nodes.
      Node* input = NodeProperties::GetControlInput(node, 0);
      CHECK(!input->op()->HasProperty(Operator::kNoThrow));
      // Type is empty.
      CheckNotTyped(node);
      break;
    }
    case IrOpcode::kIfException: {
      // IfSuccess and IfException continuation only on throwing nodes.
      Node* input = NodeProperties::GetControlInput(node, 0);
      CHECK(!input->op()->HasProperty(Operator::kNoThrow));
      // Type can be anything.
      CheckUpperIs(node, Type::Any());
      break;
    }
    case IrOpcode::kSwitch: {
      // Switch uses are Case and Default.
      int count_case = 0, count_default = 0;
      for (const Node* use : node->uses()) {
        switch (use->opcode()) {
          case IrOpcode::kIfValue: {
            for (const Node* user : node->uses()) {
              if (user != use && user->opcode() == IrOpcode::kIfValue) {
                CHECK_NE(OpParameter<int32_t>(use->op()),
                         OpParameter<int32_t>(user->op()));
              }
            }
            ++count_case;
            break;
          }
          case IrOpcode::kIfDefault: {
            ++count_default;
            break;
          }
          default: {
            V8_Fatal(__FILE__, __LINE__, "Switch #%d illegally used by #%d:%s",
                     node->id(), use->id(), use->op()->mnemonic());
            break;
          }
        }
      }
      CHECK_EQ(1, count_default);
      CHECK_EQ(node->op()->ControlOutputCount(), count_case + count_default);
      // Type is empty.
      CheckNotTyped(node);
      break;
    }
    case IrOpcode::kIfValue:
    case IrOpcode::kIfDefault:
      CHECK_EQ(IrOpcode::kSwitch,
               NodeProperties::GetControlInput(node)->opcode());
      // Type is empty.
      CheckNotTyped(node);
      break;
    case IrOpcode::kLoop:
    case IrOpcode::kMerge:
      CHECK_EQ(control_count, input_count);
      // Type is empty.
      CheckNotTyped(node);
      break;
    case IrOpcode::kDeoptimizeIf:
    case IrOpcode::kDeoptimizeUnless:
      // Type is empty.
      CheckNotTyped(node);
      break;
    case IrOpcode::kDeoptimize:
    case IrOpcode::kReturn:
    case IrOpcode::kThrow:
      // Deoptimize, Return and Throw uses are End.
      for (const Node* use : node->uses()) {
        CHECK_EQ(IrOpcode::kEnd, use->opcode());
      }
      // Type is empty.
      CheckNotTyped(node);
      break;
    case IrOpcode::kTerminate:
      // Terminates take one loop and effect.
      CHECK_EQ(1, control_count);
      CHECK_EQ(1, effect_count);
      CHECK_EQ(2, input_count);
      CHECK_EQ(IrOpcode::kLoop,
               NodeProperties::GetControlInput(node)->opcode());
      // Terminate uses are End.
      for (const Node* use : node->uses()) {
        CHECK_EQ(IrOpcode::kEnd, use->opcode());
      }
      // Type is empty.
      CheckNotTyped(node);
      break;
    case IrOpcode::kOsrNormalEntry:
    case IrOpcode::kOsrLoopEntry:
      // Osr entries take one control and effect.
      CHECK_EQ(1, control_count);
      CHECK_EQ(1, effect_count);
      CHECK_EQ(2, input_count);
      // Type is empty.
      CheckNotTyped(node);
      break;

    // Common operators
    // ----------------
    case IrOpcode::kParameter: {
      // Parameters have the start node as inputs.
      CHECK_EQ(1, input_count);
      // Parameter has an input that produces enough values.
      int const index = ParameterIndexOf(node->op());
      Node* const start = NodeProperties::GetValueInput(node, 0);
      CHECK_EQ(IrOpcode::kStart, start->opcode());
      // Currently, parameter indices start at -1 instead of 0.
      CHECK_LE(-1, index);
      CHECK_LT(index + 1, start->op()->ValueOutputCount());
      // Type can be anything.
      CheckUpperIs(node, Type::Any());
      break;
    }
    case IrOpcode::kInt32Constant:  // TODO(rossberg): rename Word32Constant?
      // Constants have no inputs.
      CHECK_EQ(0, input_count);
      // Type is a 32 bit integer, signed or unsigned.
      CheckUpperIs(node, Type::Integral32());
      break;
    case IrOpcode::kInt64Constant:
      // Constants have no inputs.
      CHECK_EQ(0, input_count);
      // Type is internal.
      // TODO(rossberg): Introduce proper Int64 type.
      CheckUpperIs(node, Type::Internal());
      break;
    case IrOpcode::kFloat32Constant:
    case IrOpcode::kFloat64Constant:
    case IrOpcode::kNumberConstant:
      // Constants have no inputs.
      CHECK_EQ(0, input_count);
      // Type is a number.
      CheckUpperIs(node, Type::Number());
      break;
    case IrOpcode::kHeapConstant:
      // Constants have no inputs.
      CHECK_EQ(0, input_count);
      // Type can be anything represented as a heap pointer.
      CheckUpperIs(node, Type::TaggedPointer());
      break;
    case IrOpcode::kExternalConstant:
      // Constants have no inputs.
      CHECK_EQ(0, input_count);
      // Type is considered internal.
      CheckUpperIs(node, Type::Internal());
      break;
    case IrOpcode::kOsrValue:
      // OSR values have a value and a control input.
      CHECK_EQ(1, control_count);
      CHECK_EQ(1, input_count);
      // Type is merged from other values in the graph and could be any.
      CheckUpperIs(node, Type::Any());
      break;
    case IrOpcode::kProjection: {
      // Projection has an input that produces enough values.
      int index = static_cast<int>(ProjectionIndexOf(node->op()));
      Node* input = NodeProperties::GetValueInput(node, 0);
      CHECK_GT(input->op()->ValueOutputCount(), index);
      // Type can be anything.
      // TODO(rossberg): Introduce tuple types for this.
      // TODO(titzer): Convince rossberg not to.
      CheckUpperIs(node, Type::Any());
      break;
    }
    case IrOpcode::kSelect: {
      CHECK_EQ(0, effect_count);
      CHECK_EQ(0, control_count);
      CHECK_EQ(3, value_count);
      break;
    }
    case IrOpcode::kPhi: {
      // Phi input count matches parent control node.
      CHECK_EQ(0, effect_count);
      CHECK_EQ(1, control_count);
      Node* control = NodeProperties::GetControlInput(node, 0);
      CHECK_EQ(value_count, control->op()->ControlInputCount());
      CHECK_EQ(input_count, 1 + value_count);
      // Type must be subsumed by all input types.
      // TODO(rossberg): for now at least, narrowing does not really hold.
      /*
      for (int i = 0; i < value_count; ++i) {
        CHECK(type_of(ValueInput(node, i))->Is(type_of(node)));
      }
      */
      break;
    }
    case IrOpcode::kEffectPhi: {
      // EffectPhi input count matches parent control node.
      CHECK_EQ(0, value_count);
      CHECK_EQ(1, control_count);
      Node* control = NodeProperties::GetControlInput(node, 0);
      CHECK_EQ(effect_count, control->op()->ControlInputCount());
      CHECK_EQ(input_count, 1 + effect_count);
      break;
    }
    case IrOpcode::kEffectSet: {
      CHECK_EQ(0, value_count);
      CHECK_EQ(0, control_count);
      CHECK_LT(1, effect_count);
      break;
    }
    case IrOpcode::kGuard:
      // TODO(bmeurer): what are the constraints on these?
      break;
    case IrOpcode::kBeginRegion:
      // TODO(rossberg): what are the constraints on these?
      break;
    case IrOpcode::kFinishRegion: {
      // TODO(rossberg): what are the constraints on these?
      // Type must be subsumed by input type.
      if (typing == TYPED) {
        Node* val = NodeProperties::GetValueInput(node, 0);
        CHECK(NodeProperties::GetType(val)->Is(NodeProperties::GetType(node)));
      }
      break;
    }
    case IrOpcode::kFrameState: {
      // TODO(jarin): what are the constraints on these?
      CHECK_EQ(5, value_count);
      CHECK_EQ(0, control_count);
      CHECK_EQ(0, effect_count);
      CHECK_EQ(6, input_count);
      for (int i = 0; i < 3; ++i) {
        CHECK(NodeProperties::GetValueInput(node, i)->opcode() ==
                  IrOpcode::kStateValues ||
              NodeProperties::GetValueInput(node, i)->opcode() ==
                  IrOpcode::kTypedStateValues);
      }
      break;
    }
    case IrOpcode::kStateValues:
    case IrOpcode::kObjectState:
    case IrOpcode::kTypedStateValues:
      // TODO(jarin): what are the constraints on these?
      break;
    case IrOpcode::kCall:
      // TODO(rossberg): what are the constraints on these?
      break;
    case IrOpcode::kTailCall:
      // TODO(bmeurer): what are the constraints on these?
      break;

    // JavaScript operators
    // --------------------
    case IrOpcode::kJSEqual:
    case IrOpcode::kJSNotEqual:
    case IrOpcode::kJSStrictEqual:
    case IrOpcode::kJSStrictNotEqual:
    case IrOpcode::kJSLessThan:
    case IrOpcode::kJSGreaterThan:
    case IrOpcode::kJSLessThanOrEqual:
    case IrOpcode::kJSGreaterThanOrEqual:
      // Type is Boolean.
      CheckUpperIs(node, Type::Boolean());
      break;

    case IrOpcode::kJSBitwiseOr:
    case IrOpcode::kJSBitwiseXor:
    case IrOpcode::kJSBitwiseAnd:
    case IrOpcode::kJSShiftLeft:
    case IrOpcode::kJSShiftRight:
    case IrOpcode::kJSShiftRightLogical:
      // Type is 32 bit integral.
      CheckUpperIs(node, Type::Integral32());
      break;
    case IrOpcode::kJSAdd:
      // Type is Number or String.
      CheckUpperIs(node, Type::NumberOrString());
      break;
    case IrOpcode::kJSSubtract:
    case IrOpcode::kJSMultiply:
    case IrOpcode::kJSDivide:
    case IrOpcode::kJSModulus:
      // Type is Number.
      CheckUpperIs(node, Type::Number());
      break;

    case IrOpcode::kJSToBoolean:
      // Type is Boolean.
      CheckUpperIs(node, Type::Boolean());
      break;
    case IrOpcode::kJSToInteger:
      // Type is OrderedNumber.
      CheckUpperIs(node, Type::OrderedNumber());
      break;
    case IrOpcode::kJSToLength:
      // Type is OrderedNumber.
      CheckUpperIs(node, Type::OrderedNumber());
      break;
    case IrOpcode::kJSToName:
      // Type is Name.
      CheckUpperIs(node, Type::Name());
      break;
    case IrOpcode::kJSToNumber:
      // Type is Number.
      CheckUpperIs(node, Type::Number());
      break;
    case IrOpcode::kJSToString:
      // Type is String.
      CheckUpperIs(node, Type::String());
      break;
    case IrOpcode::kJSToObject:
      // Type is Receiver.
      CheckUpperIs(node, Type::Receiver());
      break;

    case IrOpcode::kJSCreate:
      // Type is Object.
      CheckUpperIs(node, Type::Object());
      break;
    case IrOpcode::kJSCreateArguments:
      // Type is OtherObject.
      CheckUpperIs(node, Type::OtherObject());
      break;
    case IrOpcode::kJSCreateArray:
      // Type is OtherObject.
      CheckUpperIs(node, Type::OtherObject());
      break;
    case IrOpcode::kJSCreateClosure:
      // Type is Function.
      CheckUpperIs(node, Type::Function());
      break;
    case IrOpcode::kJSCreateIterResultObject:
      // Type is OtherObject.
      CheckUpperIs(node, Type::OtherObject());
      break;
    case IrOpcode::kJSCreateLiteralArray:
    case IrOpcode::kJSCreateLiteralObject:
    case IrOpcode::kJSCreateLiteralRegExp:
      // Type is OtherObject.
      CheckUpperIs(node, Type::OtherObject());
      break;
    case IrOpcode::kJSLoadProperty:
    case IrOpcode::kJSLoadNamed:
    case IrOpcode::kJSLoadGlobal:
      // Type can be anything.
      CheckUpperIs(node, Type::Any());
      break;
    case IrOpcode::kJSStoreProperty:
    case IrOpcode::kJSStoreNamed:
    case IrOpcode::kJSStoreGlobal:
      // Type is empty.
      CheckNotTyped(node);
      break;
    case IrOpcode::kJSDeleteProperty:
    case IrOpcode::kJSHasProperty:
    case IrOpcode::kJSInstanceOf:
      // Type is Boolean.
      CheckUpperIs(node, Type::Boolean());
      break;
    case IrOpcode::kJSTypeOf:
      // Type is String.
      CheckUpperIs(node, Type::String());
      break;

    case IrOpcode::kJSLoadContext:
      // Type can be anything.
      CheckUpperIs(node, Type::Any());
      break;
    case IrOpcode::kJSStoreContext:
      // Type is empty.
      CheckNotTyped(node);
      break;
    case IrOpcode::kJSCreateFunctionContext:
    case IrOpcode::kJSCreateCatchContext:
    case IrOpcode::kJSCreateWithContext:
    case IrOpcode::kJSCreateBlockContext:
    case IrOpcode::kJSCreateModuleContext:
    case IrOpcode::kJSCreateScriptContext: {
      // Type is Context, and operand is Internal.
      Node* context = NodeProperties::GetContextInput(node);
      // TODO(rossberg): This should really be Is(Internal), but the typer
      // currently can't do backwards propagation.
      CheckUpperMaybe(context, Type::Internal());
      if (typing == TYPED) CHECK(NodeProperties::GetType(node)->IsContext());
      break;
    }

    case IrOpcode::kJSCallConstruct:
    case IrOpcode::kJSConvertReceiver:
      // Type is Receiver.
      CheckUpperIs(node, Type::Receiver());
      break;
    case IrOpcode::kJSCallFunction:
    case IrOpcode::kJSCallRuntime:
    case IrOpcode::kJSYield:
      // Type can be anything.
      CheckUpperIs(node, Type::Any());
      break;

    case IrOpcode::kJSForInPrepare: {
      // TODO(bmeurer): What are the constraints on thse?
      CheckUpperIs(node, Type::Any());
      break;
    }
    case IrOpcode::kJSForInDone: {
      // TODO(bmeurer): OSR breaks this invariant, although the node is not user
      // visible, so we know it is safe (fullcodegen has an unsigned smi there).
      // CheckValueInputIs(node, 0, Type::UnsignedSmall());
      break;
    }
    case IrOpcode::kJSForInNext: {
      CheckUpperIs(node, Type::Union(Type::Name(), Type::Undefined(), zone));
      break;
    }
    case IrOpcode::kJSForInStep: {
      // TODO(bmeurer): OSR breaks this invariant, although the node is not user
      // visible, so we know it is safe (fullcodegen has an unsigned smi there).
      // CheckValueInputIs(node, 0, Type::UnsignedSmall());
      CheckUpperIs(node, Type::UnsignedSmall());
      break;
    }

    case IrOpcode::kJSLoadMessage:
    case IrOpcode::kJSStoreMessage:
      break;

    case IrOpcode::kJSStackCheck:
      // Type is empty.
      CheckNotTyped(node);
      break;

    // Simplified operators
    // -------------------------------
    case IrOpcode::kBooleanNot:
      // Boolean -> Boolean
      CheckValueInputIs(node, 0, Type::Boolean());
      CheckUpperIs(node, Type::Boolean());
      break;
    case IrOpcode::kBooleanToNumber:
      // Boolean -> Number
      CheckValueInputIs(node, 0, Type::Boolean());
      CheckUpperIs(node, Type::Number());
      break;
    case IrOpcode::kNumberEqual:
    case IrOpcode::kNumberLessThan:
    case IrOpcode::kNumberLessThanOrEqual:
      // (Number, Number) -> Boolean
      CheckValueInputIs(node, 0, Type::Number());
      CheckValueInputIs(node, 1, Type::Number());
      CheckUpperIs(node, Type::Boolean());
      break;
    case IrOpcode::kNumberAdd:
    case IrOpcode::kNumberSubtract:
    case IrOpcode::kNumberMultiply:
    case IrOpcode::kNumberDivide:
    case IrOpcode::kNumberModulus:
      // (Number, Number) -> Number
      CheckValueInputIs(node, 0, Type::Number());
      CheckValueInputIs(node, 1, Type::Number());
      // TODO(rossberg): activate once we retype after opcode changes.
      // CheckUpperIs(node, Type::Number());
      break;
    case IrOpcode::kNumberBitwiseOr:
    case IrOpcode::kNumberBitwiseXor:
    case IrOpcode::kNumberBitwiseAnd:
      // (Signed32, Signed32) -> Signed32
      CheckValueInputIs(node, 0, Type::Signed32());
      CheckValueInputIs(node, 1, Type::Signed32());
      CheckUpperIs(node, Type::Signed32());
      break;
    case IrOpcode::kNumberShiftLeft:
    case IrOpcode::kNumberShiftRight:
      // (Signed32, Unsigned32) -> Signed32
      CheckValueInputIs(node, 0, Type::Signed32());
      CheckValueInputIs(node, 1, Type::Unsigned32());
      CheckUpperIs(node, Type::Signed32());
      break;
    case IrOpcode::kNumberShiftRightLogical:
      // (Unsigned32, Unsigned32) -> Unsigned32
      CheckValueInputIs(node, 0, Type::Unsigned32());
      CheckValueInputIs(node, 1, Type::Unsigned32());
      CheckUpperIs(node, Type::Unsigned32());
      break;
    case IrOpcode::kNumberImul:
      // (Unsigned32, Unsigned32) -> Signed32
      CheckValueInputIs(node, 0, Type::Unsigned32());
      CheckValueInputIs(node, 1, Type::Unsigned32());
      CheckUpperIs(node, Type::Signed32());
      break;
    case IrOpcode::kNumberClz32:
      // Unsigned32 -> Unsigned32
      CheckValueInputIs(node, 0, Type::Unsigned32());
      CheckUpperIs(node, Type::Unsigned32());
      break;
    case IrOpcode::kNumberCeil:
    case IrOpcode::kNumberFloor:
    case IrOpcode::kNumberRound:
    case IrOpcode::kNumberTrunc:
      // Number -> Number
      CheckValueInputIs(node, 0, Type::Number());
      CheckUpperIs(node, Type::Number());
      break;
    case IrOpcode::kNumberToInt32:
      // Number -> Signed32
      CheckValueInputIs(node, 0, Type::Number());
      CheckUpperIs(node, Type::Signed32());
      break;
    case IrOpcode::kNumberToUint32:
      // Number -> Unsigned32
      CheckValueInputIs(node, 0, Type::Number());
      CheckUpperIs(node, Type::Unsigned32());
      break;
    case IrOpcode::kNumberIsHoleNaN:
      // Number -> Boolean
      CheckValueInputIs(node, 0, Type::Number());
      CheckUpperIs(node, Type::Boolean());
      break;
    case IrOpcode::kPlainPrimitiveToNumber:
      // PlainPrimitive -> Number
      CheckValueInputIs(node, 0, Type::PlainPrimitive());
      CheckUpperIs(node, Type::Number());
      break;
    case IrOpcode::kStringEqual:
    case IrOpcode::kStringLessThan:
    case IrOpcode::kStringLessThanOrEqual:
      // (String, String) -> Boolean
      CheckValueInputIs(node, 0, Type::String());
      CheckValueInputIs(node, 1, Type::String());
      CheckUpperIs(node, Type::Boolean());
      break;
    case IrOpcode::kStringToNumber:
      // String -> Number
      CheckValueInputIs(node, 0, Type::String());
      CheckUpperIs(node, Type::Number());
      break;
    case IrOpcode::kReferenceEqual: {
      // (Unique, Any) -> Boolean  and
      // (Any, Unique) -> Boolean
      CheckUpperIs(node, Type::Boolean());
      break;
    }
    case IrOpcode::kObjectIsNumber:
    case IrOpcode::kObjectIsReceiver:
    case IrOpcode::kObjectIsSmi:
    case IrOpcode::kObjectIsUndetectable:
      CheckValueInputIs(node, 0, Type::Any());
      CheckUpperIs(node, Type::Boolean());
      break;
    case IrOpcode::kAllocate:
      CheckValueInputIs(node, 0, Type::PlainNumber());
      CheckUpperIs(node, Type::TaggedPointer());
      break;

    case IrOpcode::kChangeTaggedToInt32: {
      // Signed32 /\ Tagged -> Signed32 /\ UntaggedInt32
      // TODO(neis): Activate once ChangeRepresentation works in typer.
      // Type* from = Type::Intersect(Type::Signed32(), Type::Tagged());
      // Type* to = Type::Intersect(Type::Signed32(), Type::UntaggedInt32());
      // CheckValueInputIs(node, 0, from));
      // CheckUpperIs(node, to));
      break;
    }
    case IrOpcode::kChangeTaggedToUint32: {
      // Unsigned32 /\ Tagged -> Unsigned32 /\ UntaggedInt32
      // TODO(neis): Activate once ChangeRepresentation works in typer.
      // Type* from = Type::Intersect(Type::Unsigned32(), Type::Tagged());
      // Type* to =Type::Intersect(Type::Unsigned32(), Type::UntaggedInt32());
      // CheckValueInputIs(node, 0, from));
      // CheckUpperIs(node, to));
      break;
    }
    case IrOpcode::kChangeTaggedToFloat64: {
      // Number /\ Tagged -> Number /\ UntaggedFloat64
      // TODO(neis): Activate once ChangeRepresentation works in typer.
      // Type* from = Type::Intersect(Type::Number(), Type::Tagged());
      // Type* to = Type::Intersect(Type::Number(), Type::UntaggedFloat64());
      // CheckValueInputIs(node, 0, from));
      // CheckUpperIs(node, to));
      break;
    }
    case IrOpcode::kChangeInt32ToTagged: {
      // Signed32 /\ UntaggedInt32 -> Signed32 /\ Tagged
      // TODO(neis): Activate once ChangeRepresentation works in typer.
      // Type* from =Type::Intersect(Type::Signed32(), Type::UntaggedInt32());
      // Type* to = Type::Intersect(Type::Signed32(), Type::Tagged());
      // CheckValueInputIs(node, 0, from));
      // CheckUpperIs(node, to));
      break;
    }
    case IrOpcode::kChangeUint32ToTagged: {
      // Unsigned32 /\ UntaggedInt32 -> Unsigned32 /\ Tagged
      // TODO(neis): Activate once ChangeRepresentation works in typer.
      // Type* from=Type::Intersect(Type::Unsigned32(),Type::UntaggedInt32());
      // Type* to = Type::Intersect(Type::Unsigned32(), Type::Tagged());
      // CheckValueInputIs(node, 0, from));
      // CheckUpperIs(node, to));
      break;
    }
    case IrOpcode::kChangeFloat64ToTagged: {
      // Number /\ UntaggedFloat64 -> Number /\ Tagged
      // TODO(neis): Activate once ChangeRepresentation works in typer.
      // Type* from =Type::Intersect(Type::Number(), Type::UntaggedFloat64());
      // Type* to = Type::Intersect(Type::Number(), Type::Tagged());
      // CheckValueInputIs(node, 0, from));
      // CheckUpperIs(node, to));
      break;
    }
    case IrOpcode::kChangeBoolToBit: {
      // Boolean /\ TaggedPtr -> Boolean /\ UntaggedInt1
      // TODO(neis): Activate once ChangeRepresentation works in typer.
      // Type* from = Type::Intersect(Type::Boolean(), Type::TaggedPtr());
      // Type* to = Type::Intersect(Type::Boolean(), Type::UntaggedInt1());
      // CheckValueInputIs(node, 0, from));
      // CheckUpperIs(node, to));
      break;
    }
    case IrOpcode::kChangeBitToBool: {
      // Boolean /\ UntaggedInt1 -> Boolean /\ TaggedPtr
      // TODO(neis): Activate once ChangeRepresentation works in typer.
      // Type* from = Type::Intersect(Type::Boolean(), Type::UntaggedInt1());
      // Type* to = Type::Intersect(Type::Boolean(), Type::TaggedPtr());
      // CheckValueInputIs(node, 0, from));
      // CheckUpperIs(node, to));
      break;
    }

    case IrOpcode::kLoadField:
      // Object -> fieldtype
      // TODO(rossberg): activate once machine ops are typed.
      // CheckValueInputIs(node, 0, Type::Object());
      // CheckUpperIs(node, FieldAccessOf(node->op()).type));
      break;
    case IrOpcode::kLoadBuffer:
      break;
    case IrOpcode::kLoadElement:
      // Object -> elementtype
      // TODO(rossberg): activate once machine ops are typed.
      // CheckValueInputIs(node, 0, Type::Object());
      // CheckUpperIs(node, ElementAccessOf(node->op()).type));
      break;
    case IrOpcode::kStoreField:
      // (Object, fieldtype) -> _|_
      // TODO(rossberg): activate once machine ops are typed.
      // CheckValueInputIs(node, 0, Type::Object());
      // CheckValueInputIs(node, 1, FieldAccessOf(node->op()).type));
      CheckNotTyped(node);
      break;
    case IrOpcode::kStoreBuffer:
      break;
    case IrOpcode::kStoreElement:
      // (Object, elementtype) -> _|_
      // TODO(rossberg): activate once machine ops are typed.
      // CheckValueInputIs(node, 0, Type::Object());
      // CheckValueInputIs(node, 1, ElementAccessOf(node->op()).type));
      CheckNotTyped(node);
      break;

    // Machine operators
    // -----------------------
    case IrOpcode::kLoad:
    case IrOpcode::kStore:
    case IrOpcode::kStackSlot:
    case IrOpcode::kWord32And:
    case IrOpcode::kWord32Or:
    case IrOpcode::kWord32Xor:
    case IrOpcode::kWord32Shl:
    case IrOpcode::kWord32Shr:
    case IrOpcode::kWord32Sar:
    case IrOpcode::kWord32Ror:
    case IrOpcode::kWord32Equal:
    case IrOpcode::kWord32Clz:
    case IrOpcode::kWord32Ctz:
    case IrOpcode::kWord32ReverseBits:
    case IrOpcode::kWord32Popcnt:
    case IrOpcode::kWord64And:
    case IrOpcode::kWord64Or:
    case IrOpcode::kWord64Xor:
    case IrOpcode::kWord64Shl:
    case IrOpcode::kWord64Shr:
    case IrOpcode::kWord64Sar:
    case IrOpcode::kWord64Ror:
    case IrOpcode::kWord64Clz:
    case IrOpcode::kWord64Popcnt:
    case IrOpcode::kWord64Ctz:
    case IrOpcode::kWord64ReverseBits:
    case IrOpcode::kWord64Equal:
    case IrOpcode::kInt32Add:
    case IrOpcode::kInt32AddWithOverflow:
    case IrOpcode::kInt32Sub:
    case IrOpcode::kInt32SubWithOverflow:
    case IrOpcode::kInt32Mul:
    case IrOpcode::kInt32MulHigh:
    case IrOpcode::kInt32Div:
    case IrOpcode::kInt32Mod:
    case IrOpcode::kInt32LessThan:
    case IrOpcode::kInt32LessThanOrEqual:
    case IrOpcode::kUint32Div:
    case IrOpcode::kUint32Mod:
    case IrOpcode::kUint32MulHigh:
    case IrOpcode::kUint32LessThan:
    case IrOpcode::kUint32LessThanOrEqual:
    case IrOpcode::kInt64Add:
    case IrOpcode::kInt64AddWithOverflow:
    case IrOpcode::kInt64Sub:
    case IrOpcode::kInt64SubWithOverflow:
    case IrOpcode::kInt64Mul:
    case IrOpcode::kInt64Div:
    case IrOpcode::kInt64Mod:
    case IrOpcode::kInt64LessThan:
    case IrOpcode::kInt64LessThanOrEqual:
    case IrOpcode::kUint64Div:
    case IrOpcode::kUint64Mod:
    case IrOpcode::kUint64LessThan:
    case IrOpcode::kUint64LessThanOrEqual:
    case IrOpcode::kFloat32Add:
    case IrOpcode::kFloat32Sub:
    case IrOpcode::kFloat32Mul:
    case IrOpcode::kFloat32Div:
    case IrOpcode::kFloat32Max:
    case IrOpcode::kFloat32Min:
    case IrOpcode::kFloat32Abs:
    case IrOpcode::kFloat32Sqrt:
    case IrOpcode::kFloat32Equal:
    case IrOpcode::kFloat32LessThan:
    case IrOpcode::kFloat32LessThanOrEqual:
    case IrOpcode::kFloat64Add:
    case IrOpcode::kFloat64Sub:
    case IrOpcode::kFloat64Mul:
    case IrOpcode::kFloat64Div:
    case IrOpcode::kFloat64Mod:
    case IrOpcode::kFloat64Max:
    case IrOpcode::kFloat64Min:
    case IrOpcode::kFloat64Abs:
    case IrOpcode::kFloat64Sqrt:
    case IrOpcode::kFloat32RoundDown:
    case IrOpcode::kFloat64RoundDown:
    case IrOpcode::kFloat32RoundUp:
    case IrOpcode::kFloat64RoundUp:
    case IrOpcode::kFloat32RoundTruncate:
    case IrOpcode::kFloat64RoundTruncate:
    case IrOpcode::kFloat64RoundTiesAway:
    case IrOpcode::kFloat32RoundTiesEven:
    case IrOpcode::kFloat64RoundTiesEven:
    case IrOpcode::kFloat64Equal:
    case IrOpcode::kFloat64LessThan:
    case IrOpcode::kFloat64LessThanOrEqual:
    case IrOpcode::kTruncateInt64ToInt32:
    case IrOpcode::kRoundInt32ToFloat32:
    case IrOpcode::kRoundInt64ToFloat32:
    case IrOpcode::kRoundInt64ToFloat64:
    case IrOpcode::kRoundUint32ToFloat32:
    case IrOpcode::kRoundUint64ToFloat64:
    case IrOpcode::kRoundUint64ToFloat32:
    case IrOpcode::kTruncateFloat64ToFloat32:
    case IrOpcode::kTruncateFloat64ToInt32:
    case IrOpcode::kBitcastFloat32ToInt32:
    case IrOpcode::kBitcastFloat64ToInt64:
    case IrOpcode::kBitcastInt32ToFloat32:
    case IrOpcode::kBitcastInt64ToFloat64:
    case IrOpcode::kChangeInt32ToInt64:
    case IrOpcode::kChangeUint32ToUint64:
    case IrOpcode::kChangeInt32ToFloat64:
    case IrOpcode::kChangeUint32ToFloat64:
    case IrOpcode::kChangeFloat32ToFloat64:
    case IrOpcode::kChangeFloat64ToInt32:
    case IrOpcode::kChangeFloat64ToUint32:
    case IrOpcode::kTruncateFloat64ToUint32:
    case IrOpcode::kTruncateFloat32ToInt32:
    case IrOpcode::kTruncateFloat32ToUint32:
    case IrOpcode::kTryTruncateFloat32ToInt64:
    case IrOpcode::kTryTruncateFloat64ToInt64:
    case IrOpcode::kTryTruncateFloat32ToUint64:
    case IrOpcode::kTryTruncateFloat64ToUint64:
    case IrOpcode::kFloat64ExtractLowWord32:
    case IrOpcode::kFloat64ExtractHighWord32:
    case IrOpcode::kFloat64InsertLowWord32:
    case IrOpcode::kFloat64InsertHighWord32:
    case IrOpcode::kInt32PairAdd:
    case IrOpcode::kInt32PairSub:
    case IrOpcode::kInt32PairMul:
    case IrOpcode::kWord32PairShl:
    case IrOpcode::kWord32PairShr:
    case IrOpcode::kWord32PairSar:
    case IrOpcode::kLoadStackPointer:
    case IrOpcode::kLoadFramePointer:
    case IrOpcode::kLoadParentFramePointer:
    case IrOpcode::kCheckedLoad:
    case IrOpcode::kCheckedStore:
      // TODO(rossberg): Check.
      break;
  }
}  // NOLINT(readability/fn_size)


void Verifier::Run(Graph* graph, Typing typing) {
  CHECK_NOT_NULL(graph->start());
  CHECK_NOT_NULL(graph->end());
  Zone zone(graph->zone()->allocator());
  Visitor visitor(&zone, typing);
  AllNodes all(&zone, graph);
  for (Node* node : all.live) visitor.Check(node);

  // Check the uniqueness of projections.
  for (Node* proj : all.live) {
    if (proj->opcode() != IrOpcode::kProjection) continue;
    Node* node = proj->InputAt(0);
    for (Node* other : node->uses()) {
      if (all.IsLive(other) && other != proj &&
          other->opcode() == IrOpcode::kProjection &&
          ProjectionIndexOf(other->op()) == ProjectionIndexOf(proj->op())) {
        V8_Fatal(__FILE__, __LINE__,
                 "Node #%d:%s has duplicate projections #%d and #%d",
                 node->id(), node->op()->mnemonic(), proj->id(), other->id());
      }
    }
  }
}


// -----------------------------------------------------------------------------

static bool HasDominatingDef(Schedule* schedule, Node* node,
                             BasicBlock* container, BasicBlock* use_block,
                             int use_pos) {
  BasicBlock* block = use_block;
  while (true) {
    while (use_pos >= 0) {
      if (block->NodeAt(use_pos) == node) return true;
      use_pos--;
    }
    block = block->dominator();
    if (block == nullptr) break;
    use_pos = static_cast<int>(block->NodeCount()) - 1;
    if (node == block->control_input()) return true;
  }
  return false;
}


static bool Dominates(Schedule* schedule, Node* dominator, Node* dominatee) {
  BasicBlock* dom = schedule->block(dominator);
  BasicBlock* sub = schedule->block(dominatee);
  while (sub != nullptr) {
    if (sub == dom) {
      return true;
    }
    sub = sub->dominator();
  }
  return false;
}


static void CheckInputsDominate(Schedule* schedule, BasicBlock* block,
                                Node* node, int use_pos) {
  for (int j = node->op()->ValueInputCount() - 1; j >= 0; j--) {
    BasicBlock* use_block = block;
    if (node->opcode() == IrOpcode::kPhi) {
      use_block = use_block->PredecessorAt(j);
      use_pos = static_cast<int>(use_block->NodeCount()) - 1;
    }
    Node* input = node->InputAt(j);
    if (!HasDominatingDef(schedule, node->InputAt(j), block, use_block,
                          use_pos)) {
      V8_Fatal(__FILE__, __LINE__,
               "Node #%d:%s in B%d is not dominated by input@%d #%d:%s",
               node->id(), node->op()->mnemonic(), block->rpo_number(), j,
               input->id(), input->op()->mnemonic());
    }
  }
  // Ensure that nodes are dominated by their control inputs;
  // kEnd is an exception, as unreachable blocks resulting from kMerge
  // are not in the RPO.
  if (node->op()->ControlInputCount() == 1 &&
      node->opcode() != IrOpcode::kEnd) {
    Node* ctl = NodeProperties::GetControlInput(node);
    if (!Dominates(schedule, ctl, node)) {
      V8_Fatal(__FILE__, __LINE__,
               "Node #%d:%s in B%d is not dominated by control input #%d:%s",
               node->id(), node->op()->mnemonic(), block->rpo_number(),
               ctl->id(), ctl->op()->mnemonic());
    }
  }
}


void ScheduleVerifier::Run(Schedule* schedule) {
  const size_t count = schedule->BasicBlockCount();
  Zone tmp_zone(schedule->zone()->allocator());
  Zone* zone = &tmp_zone;
  BasicBlock* start = schedule->start();
  BasicBlockVector* rpo_order = schedule->rpo_order();

  // Verify the RPO order contains only blocks from this schedule.
  CHECK_GE(count, rpo_order->size());
  for (BasicBlockVector::iterator b = rpo_order->begin(); b != rpo_order->end();
       ++b) {
    CHECK_EQ((*b), schedule->GetBlockById((*b)->id()));
    // All predecessors and successors should be in rpo and in this schedule.
    for (BasicBlock const* predecessor : (*b)->predecessors()) {
      CHECK_GE(predecessor->rpo_number(), 0);
      CHECK_EQ(predecessor, schedule->GetBlockById(predecessor->id()));
    }
    for (BasicBlock const* successor : (*b)->successors()) {
      CHECK_GE(successor->rpo_number(), 0);
      CHECK_EQ(successor, schedule->GetBlockById(successor->id()));
    }
  }

  // Verify RPO numbers of blocks.
  CHECK_EQ(start, rpo_order->at(0));  // Start should be first.
  for (size_t b = 0; b < rpo_order->size(); b++) {
    BasicBlock* block = rpo_order->at(b);
    CHECK_EQ(static_cast<int>(b), block->rpo_number());
    BasicBlock* dom = block->dominator();
    if (b == 0) {
      // All blocks except start should have a dominator.
      CHECK_NULL(dom);
    } else {
      // Check that the immediate dominator appears somewhere before the block.
      CHECK_NOT_NULL(dom);
      CHECK_LT(dom->rpo_number(), block->rpo_number());
    }
  }

  // Verify that all blocks reachable from start are in the RPO.
  BoolVector marked(static_cast<int>(count), false, zone);
  {
    ZoneQueue<BasicBlock*> queue(zone);
    queue.push(start);
    marked[start->id().ToSize()] = true;
    while (!queue.empty()) {
      BasicBlock* block = queue.front();
      queue.pop();
      for (size_t s = 0; s < block->SuccessorCount(); s++) {
        BasicBlock* succ = block->SuccessorAt(s);
        if (!marked[succ->id().ToSize()]) {
          marked[succ->id().ToSize()] = true;
          queue.push(succ);
        }
      }
    }
  }
  // Verify marked blocks are in the RPO.
  for (size_t i = 0; i < count; i++) {
    BasicBlock* block = schedule->GetBlockById(BasicBlock::Id::FromSize(i));
    if (marked[i]) {
      CHECK_GE(block->rpo_number(), 0);
      CHECK_EQ(block, rpo_order->at(block->rpo_number()));
    }
  }
  // Verify RPO blocks are marked.
  for (size_t b = 0; b < rpo_order->size(); b++) {
    CHECK(marked[rpo_order->at(b)->id().ToSize()]);
  }

  {
    // Verify the dominance relation.
    ZoneVector<BitVector*> dominators(zone);
    dominators.resize(count, nullptr);

    // Compute a set of all the nodes that dominate a given node by using
    // a forward fixpoint. O(n^2).
    ZoneQueue<BasicBlock*> queue(zone);
    queue.push(start);
    dominators[start->id().ToSize()] =
        new (zone) BitVector(static_cast<int>(count), zone);
    while (!queue.empty()) {
      BasicBlock* block = queue.front();
      queue.pop();
      BitVector* block_doms = dominators[block->id().ToSize()];
      BasicBlock* idom = block->dominator();
      if (idom != nullptr && !block_doms->Contains(idom->id().ToInt())) {
        V8_Fatal(__FILE__, __LINE__, "Block B%d is not dominated by B%d",
                 block->rpo_number(), idom->rpo_number());
      }
      for (size_t s = 0; s < block->SuccessorCount(); s++) {
        BasicBlock* succ = block->SuccessorAt(s);
        BitVector* succ_doms = dominators[succ->id().ToSize()];

        if (succ_doms == nullptr) {
          // First time visiting the node. S.doms = B U B.doms
          succ_doms = new (zone) BitVector(static_cast<int>(count), zone);
          succ_doms->CopyFrom(*block_doms);
          succ_doms->Add(block->id().ToInt());
          dominators[succ->id().ToSize()] = succ_doms;
          queue.push(succ);
        } else {
          // Nth time visiting the successor. S.doms = S.doms ^ (B U B.doms)
          bool had = succ_doms->Contains(block->id().ToInt());
          if (had) succ_doms->Remove(block->id().ToInt());
          if (succ_doms->IntersectIsChanged(*block_doms)) queue.push(succ);
          if (had) succ_doms->Add(block->id().ToInt());
        }
      }
    }

    // Verify the immediateness of dominators.
    for (BasicBlockVector::iterator b = rpo_order->begin();
         b != rpo_order->end(); ++b) {
      BasicBlock* block = *b;
      BasicBlock* idom = block->dominator();
      if (idom == nullptr) continue;
      BitVector* block_doms = dominators[block->id().ToSize()];

      for (BitVector::Iterator it(block_doms); !it.Done(); it.Advance()) {
        BasicBlock* dom =
            schedule->GetBlockById(BasicBlock::Id::FromInt(it.Current()));
        if (dom != idom &&
            !dominators[idom->id().ToSize()]->Contains(dom->id().ToInt())) {
          V8_Fatal(__FILE__, __LINE__,
                   "Block B%d is not immediately dominated by B%d",
                   block->rpo_number(), idom->rpo_number());
        }
      }
    }
  }

  // Verify phis are placed in the block of their control input.
  for (BasicBlockVector::iterator b = rpo_order->begin(); b != rpo_order->end();
       ++b) {
    for (BasicBlock::const_iterator i = (*b)->begin(); i != (*b)->end(); ++i) {
      Node* phi = *i;
      if (phi->opcode() != IrOpcode::kPhi) continue;
      // TODO(titzer): Nasty special case. Phis from RawMachineAssembler
      // schedules don't have control inputs.
      if (phi->InputCount() > phi->op()->ValueInputCount()) {
        Node* control = NodeProperties::GetControlInput(phi);
        CHECK(control->opcode() == IrOpcode::kMerge ||
              control->opcode() == IrOpcode::kLoop);
        CHECK_EQ((*b), schedule->block(control));
      }
    }
  }

  // Verify that all uses are dominated by their definitions.
  for (BasicBlockVector::iterator b = rpo_order->begin(); b != rpo_order->end();
       ++b) {
    BasicBlock* block = *b;

    // Check inputs to control for this block.
    Node* control = block->control_input();
    if (control != nullptr) {
      CHECK_EQ(block, schedule->block(control));
      CheckInputsDominate(schedule, block, control,
                          static_cast<int>(block->NodeCount()) - 1);
    }
    // Check inputs for all nodes in the block.
    for (size_t i = 0; i < block->NodeCount(); i++) {
      Node* node = block->NodeAt(i);
      CheckInputsDominate(schedule, block, node, static_cast<int>(i) - 1);
    }
  }
}


#ifdef DEBUG

// static
void Verifier::VerifyNode(Node* node) {
  CHECK_EQ(OperatorProperties::GetTotalInputCount(node->op()),
           node->InputCount());
  // If this node has no effect or no control outputs,
  // we check that no its uses are effect or control inputs.
  bool check_no_control = node->op()->ControlOutputCount() == 0;
  bool check_no_effect = node->op()->EffectOutputCount() == 0;
  bool check_no_frame_state = node->opcode() != IrOpcode::kFrameState;
  if (check_no_effect || check_no_control) {
    for (Edge edge : node->use_edges()) {
      Node* const user = edge.from();
      CHECK(!user->IsDead());
      if (NodeProperties::IsControlEdge(edge)) {
        CHECK(!check_no_control);
      } else if (NodeProperties::IsEffectEdge(edge)) {
        CHECK(!check_no_effect);
      } else if (NodeProperties::IsFrameStateEdge(edge)) {
        CHECK(!check_no_frame_state);
      }
    }
  }
  // Frame state inputs should be frame states (or sentinels).
  for (int i = 0; i < OperatorProperties::GetFrameStateInputCount(node->op());
       i++) {
    Node* input = NodeProperties::GetFrameStateInput(node, i);
    CHECK(input->opcode() == IrOpcode::kFrameState ||
          input->opcode() == IrOpcode::kStart ||
          input->opcode() == IrOpcode::kDead);
  }
  // Effect inputs should be effect-producing nodes (or sentinels).
  for (int i = 0; i < node->op()->EffectInputCount(); i++) {
    Node* input = NodeProperties::GetEffectInput(node, i);
    CHECK(input->op()->EffectOutputCount() > 0 ||
          input->opcode() == IrOpcode::kDead);
  }
  // Control inputs should be control-producing nodes (or sentinels).
  for (int i = 0; i < node->op()->ControlInputCount(); i++) {
    Node* input = NodeProperties::GetControlInput(node, i);
    CHECK(input->op()->ControlOutputCount() > 0 ||
          input->opcode() == IrOpcode::kDead);
  }
}


void Verifier::VerifyEdgeInputReplacement(const Edge& edge,
                                          const Node* replacement) {
  // Check that the user does not misuse the replacement.
  DCHECK(!NodeProperties::IsControlEdge(edge) ||
         replacement->op()->ControlOutputCount() > 0);
  DCHECK(!NodeProperties::IsEffectEdge(edge) ||
         replacement->op()->EffectOutputCount() > 0);
  DCHECK(!NodeProperties::IsFrameStateEdge(edge) ||
         replacement->opcode() == IrOpcode::kFrameState);
}

#endif  // DEBUG

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