test/cctest/compiler/test-machine-operator-reducer.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/base/overflowing-math.h"
#include "src/base/utils/random-number-generator.h"
#include "src/compiler/js-graph.h"
#include "src/compiler/machine-operator-reducer.h"
#include "src/compiler/operator-properties.h"
#include "src/compiler/typer.h"
#include "src/objects-inl.h"
#include "test/cctest/cctest.h"
#include "test/cctest/compiler/value-helper.h"

namespace v8 {
namespace internal {
namespace compiler {

template <typename T>
const Operator* NewConstantOperator(CommonOperatorBuilder* common,
                                    volatile T value);

template <>
const Operator* NewConstantOperator<int32_t>(CommonOperatorBuilder* common,
                                             volatile int32_t value) {
  return common->Int32Constant(value);
}

template <>
const Operator* NewConstantOperator<int64_t>(CommonOperatorBuilder* common,
                                             volatile int64_t value) {
  return common->Int64Constant(value);
}

template <>
const Operator* NewConstantOperator<double>(CommonOperatorBuilder* common,
                                            volatile double value) {
  return common->Float64Constant(value);
}

template <>
const Operator* NewConstantOperator<float>(CommonOperatorBuilder* common,
                                           volatile float value) {
  return common->Float32Constant(value);
}

template <typename T>
T ValueOfOperator(const Operator* op);

template <>
int32_t ValueOfOperator<int32_t>(const Operator* op) {
  CHECK_EQ(IrOpcode::kInt32Constant, op->opcode());
  return OpParameter<int32_t>(op);
}

template <>
int64_t ValueOfOperator<int64_t>(const Operator* op) {
  CHECK_EQ(IrOpcode::kInt64Constant, op->opcode());
  return OpParameter<int64_t>(op);
}

template <>
float ValueOfOperator<float>(const Operator* op) {
  CHECK_EQ(IrOpcode::kFloat32Constant, op->opcode());
  return OpParameter<float>(op);
}

template <>
double ValueOfOperator<double>(const Operator* op) {
  CHECK_EQ(IrOpcode::kFloat64Constant, op->opcode());
  return OpParameter<double>(op);
}


class ReducerTester : public HandleAndZoneScope {
 public:
  explicit ReducerTester(int num_parameters = 0,
                         MachineOperatorBuilder::Flags flags =
                             MachineOperatorBuilder::kAllOptionalOps)
      : isolate(main_isolate()),
        binop(nullptr),
        unop(nullptr),
        machine(main_zone(), MachineType::PointerRepresentation(), flags),
        common(main_zone()),
        graph(main_zone()),
        javascript(main_zone()),
        jsgraph(isolate, &graph, &common, &javascript, nullptr, &machine),
        maxuint32(Constant<int32_t>(kMaxUInt32)),
        graph_reducer(main_zone(), &graph, jsgraph.Dead()) {
    Node* s = graph.NewNode(common.Start(num_parameters));
    graph.SetStart(s);
  }

  Isolate* isolate;
  const Operator* binop;
  const Operator* unop;
  MachineOperatorBuilder machine;
  CommonOperatorBuilder common;
  Graph graph;
  JSOperatorBuilder javascript;
  JSGraph jsgraph;
  Node* maxuint32;
  GraphReducer graph_reducer;

  template <typename T>
  Node* Constant(volatile T value) {
    return graph.NewNode(NewConstantOperator<T>(&common, value));
  }

  template <typename T>
  const T ValueOf(const Operator* op) {
    return ValueOfOperator<T>(op);
  }

  // Check that the reduction of this binop applied to constants {a} and {b}
  // yields the {expect} value.
  template <typename T>
  void CheckFoldBinop(volatile T expect, volatile T a, volatile T b) {
    CheckFoldBinop<T>(expect, Constant<T>(a), Constant<T>(b));
  }

  // Check that the reduction of this binop applied to {a} and {b} yields
  // the {expect} value.
  template <typename T>
  void CheckFoldBinop(volatile T expect, Node* a, Node* b) {
    CHECK(binop);
    Node* n = CreateBinopNode(a, b);
    MachineOperatorReducer reducer(&graph_reducer, &jsgraph);
    Reduction reduction = reducer.Reduce(n);
    CHECK(reduction.Changed());
    CHECK_NE(n, reduction.replacement());
    // Deal with NaNs.
    if (expect == expect) {
      // We do not expect a NaN, check for equality.
      CHECK_EQ(expect, ValueOf<T>(reduction.replacement()->op()));
    } else {
      // Check for NaN.
      T result = ValueOf<T>(reduction.replacement()->op());
      CHECK_NE(result, result);
    }
  }

  // Check that the reduction of this binop applied to {a} and {b} yields
  // the {expect} node.
  void CheckBinop(Node* expect, Node* a, Node* b) {
    CHECK(binop);
    Node* n = CreateBinopNode(a, b);
    MachineOperatorReducer reducer(&graph_reducer, &jsgraph);
    Reduction reduction = reducer.Reduce(n);
    CHECK(reduction.Changed());
    CHECK_EQ(expect, reduction.replacement());
  }

  // Check that the reduction of this binop applied to {left} and {right} yields
  // this binop applied to {left_expect} and {right_expect}.
  void CheckFoldBinop(Node* left_expect, Node* right_expect, Node* left,
                      Node* right) {
    CHECK(binop);
    Node* n = CreateBinopNode(left, right);
    MachineOperatorReducer reducer(&graph_reducer, &jsgraph);
    Reduction reduction = reducer.Reduce(n);
    CHECK(reduction.Changed());
    CHECK_EQ(binop, reduction.replacement()->op());
    CHECK_EQ(left_expect, reduction.replacement()->InputAt(0));
    CHECK_EQ(right_expect, reduction.replacement()->InputAt(1));
  }

  // Check that the reduction of this binop applied to {left} and {right} yields
  // the {op_expect} applied to {left_expect} and {right_expect}.
  template <typename T>
  void CheckFoldBinop(volatile T left_expect, const Operator* op_expect,
                      Node* right_expect, Node* left, Node* right) {
    CHECK(binop);
    Node* n = CreateBinopNode(left, right);
    MachineOperatorReducer reducer(&graph_reducer, &jsgraph);
    Reduction r = reducer.Reduce(n);
    CHECK(r.Changed());
    CHECK_EQ(op_expect->opcode(), r.replacement()->op()->opcode());
    CHECK_EQ(left_expect, ValueOf<T>(r.replacement()->InputAt(0)->op()));
    CHECK_EQ(right_expect, r.replacement()->InputAt(1));
  }

  // Check that the reduction of this binop applied to {left} and {right} yields
  // the {op_expect} applied to {left_expect} and {right_expect}.
  template <typename T>
  void CheckFoldBinop(Node* left_expect, const Operator* op_expect,
                      volatile T right_expect, Node* left, Node* right) {
    CHECK(binop);
    Node* n = CreateBinopNode(left, right);
    MachineOperatorReducer reducer(&graph_reducer, &jsgraph);
    Reduction r = reducer.Reduce(n);
    CHECK(r.Changed());
    CHECK_EQ(op_expect->opcode(), r.replacement()->op()->opcode());
    CHECK_EQ(OperatorProperties::GetTotalInputCount(op_expect),
             r.replacement()->InputCount());
    CHECK_EQ(left_expect, r.replacement()->InputAt(0));
    CHECK_EQ(right_expect, ValueOf<T>(r.replacement()->InputAt(1)->op()));
  }

  // Check that if the given constant appears on the left, the reducer will
  // swap it to be on the right.
  template <typename T>
  void CheckPutConstantOnRight(volatile T constant) {
    // TODO(titzer): CHECK(binop->HasProperty(Operator::kCommutative));
    Node* p = Parameter();
    Node* k = Constant<T>(constant);
    {
      Node* n = CreateBinopNode(k, p);
      MachineOperatorReducer reducer(&graph_reducer, &jsgraph);
      Reduction reduction = reducer.Reduce(n);
      CHECK(!reduction.Changed() || reduction.replacement() == n);
      CHECK_EQ(p, n->InputAt(0));
      CHECK_EQ(k, n->InputAt(1));
    }
    {
      Node* n = CreateBinopNode(p, k);
      MachineOperatorReducer reducer(&graph_reducer, &jsgraph);
      Reduction reduction = reducer.Reduce(n);
      CHECK(!reduction.Changed());
      CHECK_EQ(p, n->InputAt(0));
      CHECK_EQ(k, n->InputAt(1));
    }
  }

  // Check that if the given constant appears on the left, the reducer will
  // *NOT* swap it to be on the right.
  template <typename T>
  void CheckDontPutConstantOnRight(volatile T constant) {
    CHECK(!binop->HasProperty(Operator::kCommutative));
    Node* p = Parameter();
    Node* k = Constant<T>(constant);
    Node* n = CreateBinopNode(k, p);
    MachineOperatorReducer reducer(&graph_reducer, &jsgraph);
    Reduction reduction = reducer.Reduce(n);
    CHECK(!reduction.Changed());
    CHECK_EQ(k, n->InputAt(0));
    CHECK_EQ(p, n->InputAt(1));
  }

  Node* Parameter(int32_t index = 0) {
    return graph.NewNode(common.Parameter(index), graph.start());
  }

 private:
  Node* CreateBinopNode(Node* left, Node* right) {
    if (binop->ControlInputCount() > 0) {
      return graph.NewNode(binop, left, right, graph.start());
    } else {
      return graph.NewNode(binop, left, right);
    }
  }
};


TEST(ReduceWord32And) {
  ReducerTester R;
  R.binop = R.machine.Word32And();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      int32_t x = pl, y = pr;
      R.CheckFoldBinop<int32_t>(x & y, x, y);
    }
  }

  R.CheckPutConstantOnRight(33);
  R.CheckPutConstantOnRight(44000);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int32_t>(0);
  Node* minus_1 = R.Constant<int32_t>(-1);

  R.CheckBinop(zero, x, zero);  // x  & 0  => 0
  R.CheckBinop(zero, zero, x);  // 0  & x  => 0
  R.CheckBinop(x, x, minus_1);  // x  & -1 => 0
  R.CheckBinop(x, minus_1, x);  // -1 & x  => 0
  R.CheckBinop(x, x, x);        // x  & x  => x
}


TEST(ReduceWord32Or) {
  ReducerTester R;
  R.binop = R.machine.Word32Or();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      int32_t x = pl, y = pr;
      R.CheckFoldBinop<int32_t>(x | y, x, y);
    }
  }

  R.CheckPutConstantOnRight(36);
  R.CheckPutConstantOnRight(44001);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int32_t>(0);
  Node* minus_1 = R.Constant<int32_t>(-1);

  R.CheckBinop(x, x, zero);           // x  & 0  => x
  R.CheckBinop(x, zero, x);           // 0  & x  => x
  R.CheckBinop(minus_1, x, minus_1);  // x  & -1 => -1
  R.CheckBinop(minus_1, minus_1, x);  // -1 & x  => -1
  R.CheckBinop(x, x, x);              // x  & x  => x
}


TEST(ReduceWord32Xor) {
  ReducerTester R;
  R.binop = R.machine.Word32Xor();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      int32_t x = pl, y = pr;
      R.CheckFoldBinop<int32_t>(x ^ y, x, y);
    }
  }

  R.CheckPutConstantOnRight(39);
  R.CheckPutConstantOnRight(4403);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int32_t>(0);

  R.CheckBinop(x, x, zero);            // x ^ 0  => x
  R.CheckBinop(x, zero, x);            // 0 ^ x  => x
  R.CheckFoldBinop<int32_t>(0, x, x);  // x ^ x  => 0
}


TEST(ReduceWord32Shl) {
  ReducerTester R;
  R.binop = R.machine.Word32Shl();

  // TODO(titzer): out of range shifts
  FOR_INT32_INPUTS(i) {
    for (int y = 0; y < 32; y++) {
      int32_t x = i;
      R.CheckFoldBinop<int32_t>(base::ShlWithWraparound(x, y), x, y);
    }
  }

  R.CheckDontPutConstantOnRight(44);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int32_t>(0);

  R.CheckBinop(x, x, zero);  // x << 0  => x
}

TEST(ReduceWord64Shl) {
  ReducerTester R;
  R.binop = R.machine.Word64Shl();

  FOR_INT64_INPUTS(i) {
    for (int64_t y = 0; y < 64; y++) {
      int64_t x = i;
      R.CheckFoldBinop<int64_t>(base::ShlWithWraparound(x, y), x, y);
    }
  }

  R.CheckDontPutConstantOnRight(44);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int64_t>(0);

  R.CheckBinop(x, x, zero);  // x << 0  => x
}

TEST(ReduceWord32Shr) {
  ReducerTester R;
  R.binop = R.machine.Word32Shr();

  // TODO(titzer): test out of range shifts
  FOR_UINT32_INPUTS(i) {
    for (uint32_t y = 0; y < 32; y++) {
      uint32_t x = i;
      R.CheckFoldBinop<int32_t>(x >> y, x, y);
    }
  }

  R.CheckDontPutConstantOnRight(44);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int32_t>(0);

  R.CheckBinop(x, x, zero);  // x >>> 0  => x
}

TEST(ReduceWord64Shr) {
  ReducerTester R;
  R.binop = R.machine.Word64Shr();

  FOR_UINT64_INPUTS(i) {
    for (uint64_t y = 0; y < 64; y++) {
      uint64_t x = i;
      R.CheckFoldBinop<int64_t>(x >> y, x, y);
    }
  }

  R.CheckDontPutConstantOnRight(44);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int64_t>(0);

  R.CheckBinop(x, x, zero);  // x >>> 0  => x
}

TEST(ReduceWord32Sar) {
  ReducerTester R;
  R.binop = R.machine.Word32Sar();

  // TODO(titzer): test out of range shifts
  FOR_INT32_INPUTS(i) {
    for (int32_t y = 0; y < 32; y++) {
      int32_t x = i;
      R.CheckFoldBinop<int32_t>(x >> y, x, y);
    }
  }

  R.CheckDontPutConstantOnRight(44);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int32_t>(0);

  R.CheckBinop(x, x, zero);  // x >> 0  => x
}

TEST(ReduceWord64Sar) {
  ReducerTester R;
  R.binop = R.machine.Word64Sar();

  FOR_INT64_INPUTS(i) {
    for (int64_t y = 0; y < 64; y++) {
      int64_t x = i;
      R.CheckFoldBinop<int64_t>(x >> y, x, y);
    }
  }

  R.CheckDontPutConstantOnRight(44);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int64_t>(0);

  R.CheckBinop(x, x, zero);  // x >> 0  => x
}

static void CheckJsShift(ReducerTester* R) {
  CHECK(R->machine.Word32ShiftIsSafe());

  Node* x = R->Parameter(0);
  Node* y = R->Parameter(1);
  Node* thirty_one = R->Constant<int32_t>(0x1F);
  Node* y_and_thirty_one =
      R->graph.NewNode(R->machine.Word32And(), y, thirty_one);

  // If the underlying machine shift instructions 'and' their right operand
  // with 0x1F then:  x << (y & 0x1F) => x << y
  R->CheckFoldBinop(x, y, x, y_and_thirty_one);
}


TEST(ReduceJsShifts) {
  ReducerTester R(0, MachineOperatorBuilder::kWord32ShiftIsSafe);

  R.binop = R.machine.Word32Shl();
  CheckJsShift(&R);

  R.binop = R.machine.Word32Shr();
  CheckJsShift(&R);

  R.binop = R.machine.Word32Sar();
  CheckJsShift(&R);
}


TEST(Word32Equal) {
  ReducerTester R;
  R.binop = R.machine.Word32Equal();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      int32_t x = pl, y = pr;
      R.CheckFoldBinop<int32_t>(x == y ? 1 : 0, x, y);
    }
  }

  R.CheckPutConstantOnRight(48);
  R.CheckPutConstantOnRight(-48);

  Node* x = R.Parameter(0);
  Node* y = R.Parameter(1);
  Node* zero = R.Constant<int32_t>(0);
  Node* sub = R.graph.NewNode(R.machine.Int32Sub(), x, y);

  R.CheckFoldBinop<int32_t>(1, x, x);  // x == x  => 1
  R.CheckFoldBinop(x, y, sub, zero);   // x - y == 0  => x == y
  R.CheckFoldBinop(x, y, zero, sub);   // 0 == x - y  => x == y
}


TEST(ReduceInt32Add) {
  ReducerTester R;
  R.binop = R.machine.Int32Add();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      int32_t x = pl, y = pr;
      R.CheckFoldBinop<int32_t>(base::AddWithWraparound(x, y), x, y);
    }
  }

  R.CheckPutConstantOnRight(41);
  R.CheckPutConstantOnRight(4407);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int32_t>(0);

  R.CheckBinop(x, x, zero);  // x + 0  => x
  R.CheckBinop(x, zero, x);  // 0 + x  => x
}

TEST(ReduceInt64Add) {
  ReducerTester R;
  R.binop = R.machine.Int64Add();

  FOR_INT64_INPUTS(pl) {
    FOR_INT64_INPUTS(pr) {
      int64_t x = pl, y = pr;
      R.CheckFoldBinop<int64_t>(base::AddWithWraparound(x, y), x, y);
    }
  }

  R.CheckPutConstantOnRight(41);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int64_t>(0);
  R.CheckBinop(x, x, zero);  // x + 0 => x
  R.CheckBinop(x, zero, x);  // 0 + x => x
}

TEST(ReduceInt32Sub) {
  ReducerTester R;
  R.binop = R.machine.Int32Sub();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      int32_t x = pl, y = pr;
      R.CheckFoldBinop<int32_t>(base::SubWithWraparound(x, y), x, y);
    }
  }

  R.CheckDontPutConstantOnRight(412);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int32_t>(0);

  R.CheckBinop(x, x, zero);  // x - 0  => x
}

TEST(ReduceInt64Sub) {
  ReducerTester R;
  R.binop = R.machine.Int64Sub();

  FOR_INT64_INPUTS(pl) {
    FOR_INT64_INPUTS(pr) {
      int64_t x = pl, y = pr;
      R.CheckFoldBinop<int64_t>(base::SubWithWraparound(x, y), x, y);
    }
  }

  R.CheckDontPutConstantOnRight(42);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int64_t>(0);

  R.CheckBinop(x, x, zero);            // x - 0 => x
  R.CheckFoldBinop<int64_t>(0, x, x);  // x - x => 0

  Node* k = R.Constant<int64_t>(6);

  R.CheckFoldBinop<int64_t>(x, R.machine.Int64Add(), -6, x,
                            k);  // x - K => x + -K
}

TEST(ReduceInt32Mul) {
  ReducerTester R;
  R.binop = R.machine.Int32Mul();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      int32_t x = pl, y = pr;
      R.CheckFoldBinop<int32_t>(base::MulWithWraparound(x, y), x, y);
    }
  }

  R.CheckPutConstantOnRight(4111);
  R.CheckPutConstantOnRight(-4407);

  Node* x = R.Parameter();
  Node* zero = R.Constant<int32_t>(0);
  Node* one = R.Constant<int32_t>(1);
  Node* minus_one = R.Constant<int32_t>(-1);

  R.CheckBinop(zero, x, zero);  // x * 0  => 0
  R.CheckBinop(zero, zero, x);  // 0 * x  => 0
  R.CheckBinop(x, x, one);      // x * 1  => x
  R.CheckBinop(x, one, x);      // 1 * x  => x
  R.CheckFoldBinop<int32_t>(0, R.machine.Int32Sub(), x, minus_one,
                            x);  // -1 * x  => 0 - x
  R.CheckFoldBinop<int32_t>(0, R.machine.Int32Sub(), x, x,
                            minus_one);  // x * -1  => 0 - x

  for (int32_t n = 1; n < 31; ++n) {
    Node* multiplier = R.Constant<int32_t>(1 << n);
    R.CheckFoldBinop<int32_t>(x, R.machine.Word32Shl(), n, x,
                              multiplier);  // x * 2^n => x << n
    R.CheckFoldBinop<int32_t>(x, R.machine.Word32Shl(), n, multiplier,
                              x);  // 2^n * x => x << n
  }
}


TEST(ReduceInt32Div) {
  ReducerTester R;
  R.binop = R.machine.Int32Div();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      int32_t x = pl, y = pr;
      if (y == 0) continue;              // TODO(titzer): test / 0
      int32_t r = y == -1 ? base::NegateWithWraparound(x)
                          : x / y;  // INT_MIN / -1 may explode in C
      R.CheckFoldBinop<int32_t>(r, x, y);
    }
  }

  R.CheckDontPutConstantOnRight(41111);
  R.CheckDontPutConstantOnRight(-44071);

  Node* x = R.Parameter();
  Node* one = R.Constant<int32_t>(1);
  Node* minus_one = R.Constant<int32_t>(-1);

  R.CheckBinop(x, x, one);  // x / 1  => x
  // TODO(titzer):                          // 0 / x  => 0 if x != 0
  // TODO(titzer):                          // x / 2^n => x >> n and round
  R.CheckFoldBinop<int32_t>(0, R.machine.Int32Sub(), x, x,
                            minus_one);  // x / -1  => 0 - x
}


TEST(ReduceUint32Div) {
  ReducerTester R;
  R.binop = R.machine.Uint32Div();

  FOR_UINT32_INPUTS(pl) {
    FOR_UINT32_INPUTS(pr) {
      uint32_t x = pl, y = pr;
      if (y == 0) continue;  // TODO(titzer): test / 0
      R.CheckFoldBinop<int32_t>(x / y, x, y);
    }
  }

  R.CheckDontPutConstantOnRight(41311);
  R.CheckDontPutConstantOnRight(-44371);

  Node* x = R.Parameter();
  Node* one = R.Constant<int32_t>(1);

  R.CheckBinop(x, x, one);  // x / 1  => x
  // TODO(titzer):                            // 0 / x  => 0 if x != 0

  for (uint32_t n = 1; n < 32; ++n) {
    Node* divisor = R.Constant<int32_t>(1u << n);
    R.CheckFoldBinop<int32_t>(x, R.machine.Word32Shr(), n, x,
                              divisor);  // x / 2^n => x >> n
  }
}


TEST(ReduceInt32Mod) {
  ReducerTester R;
  R.binop = R.machine.Int32Mod();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      int32_t x = pl, y = pr;
      if (y == 0) continue;             // TODO(titzer): test % 0
      int32_t r = y == -1 ? 0 : x % y;  // INT_MIN % -1 may explode in C
      R.CheckFoldBinop<int32_t>(r, x, y);
    }
  }

  R.CheckDontPutConstantOnRight(413);
  R.CheckDontPutConstantOnRight(-4401);

  Node* x = R.Parameter();
  Node* one = R.Constant<int32_t>(1);

  R.CheckFoldBinop<int32_t>(0, x, one);  // x % 1  => 0
  // TODO(titzer):                       // x % 2^n => x & 2^n-1 and round
}


TEST(ReduceUint32Mod) {
  ReducerTester R;
  R.binop = R.machine.Uint32Mod();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      uint32_t x = pl, y = pr;
      if (y == 0) continue;  // TODO(titzer): test x % 0
      R.CheckFoldBinop<int32_t>(x % y, x, y);
    }
  }

  R.CheckDontPutConstantOnRight(417);
  R.CheckDontPutConstantOnRight(-4371);

  Node* x = R.Parameter();
  Node* one = R.Constant<int32_t>(1);

  R.CheckFoldBinop<int32_t>(0, x, one);  // x % 1  => 0

  for (uint32_t n = 1; n < 32; ++n) {
    Node* divisor = R.Constant<int32_t>(1u << n);
    R.CheckFoldBinop<int32_t>(x, R.machine.Word32And(), (1u << n) - 1, x,
                              divisor);  // x % 2^n => x & 2^n-1
  }
}


TEST(ReduceInt32LessThan) {
  ReducerTester R;
  R.binop = R.machine.Int32LessThan();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      int32_t x = pl, y = pr;
      R.CheckFoldBinop<int32_t>(x < y ? 1 : 0, x, y);
    }
  }

  R.CheckDontPutConstantOnRight(41399);
  R.CheckDontPutConstantOnRight(-440197);

  Node* x = R.Parameter(0);

  R.CheckFoldBinop<int32_t>(0, x, x);  // x < x  => 0
}


TEST(ReduceInt32LessThanOrEqual) {
  ReducerTester R;
  R.binop = R.machine.Int32LessThanOrEqual();

  FOR_INT32_INPUTS(pl) {
    FOR_INT32_INPUTS(pr) {
      int32_t x = pl, y = pr;
      R.CheckFoldBinop<int32_t>(x <= y ? 1 : 0, x, y);
    }
  }

  FOR_INT32_INPUTS(i) { R.CheckDontPutConstantOnRight<int32_t>(i); }

  Node* x = R.Parameter(0);

  R.CheckFoldBinop<int32_t>(1, x, x);  // x <= x => 1
}


TEST(ReduceUint32LessThan) {
  ReducerTester R;
  R.binop = R.machine.Uint32LessThan();

  FOR_UINT32_INPUTS(pl) {
    FOR_UINT32_INPUTS(pr) {
      uint32_t x = pl, y = pr;
      R.CheckFoldBinop<int32_t>(x < y ? 1 : 0, x, y);
    }
  }

  R.CheckDontPutConstantOnRight(41399);
  R.CheckDontPutConstantOnRight(-440197);

  Node* x = R.Parameter();
  Node* max = R.maxuint32;
  Node* zero = R.Constant<int32_t>(0);

  R.CheckFoldBinop<int32_t>(0, max, x);   // M < x  => 0
  R.CheckFoldBinop<int32_t>(0, x, zero);  // x < 0  => 0
  R.CheckFoldBinop<int32_t>(0, x, x);     // x < x  => 0
}


TEST(ReduceUint32LessThanOrEqual) {
  ReducerTester R;
  R.binop = R.machine.Uint32LessThanOrEqual();

  FOR_UINT32_INPUTS(pl) {
    FOR_UINT32_INPUTS(pr) {
      uint32_t x = pl, y = pr;
      R.CheckFoldBinop<int32_t>(x <= y ? 1 : 0, x, y);
    }
  }

  R.CheckDontPutConstantOnRight(41399);
  R.CheckDontPutConstantOnRight(-440197);

  Node* x = R.Parameter();
  Node* max = R.maxuint32;
  Node* zero = R.Constant<int32_t>(0);

  R.CheckFoldBinop<int32_t>(1, x, max);   // x <= M  => 1
  R.CheckFoldBinop<int32_t>(1, zero, x);  // 0 <= x  => 1
  R.CheckFoldBinop<int32_t>(1, x, x);     // x <= x  => 1
}


TEST(ReduceLoadStore) {
  ReducerTester R;

  Node* base = R.Constant<int32_t>(11);
  Node* index = R.Constant<int32_t>(4);
  Node* load = R.graph.NewNode(R.machine.Load(MachineType::Int32()), base,
                               index, R.graph.start(), R.graph.start());

  {
    MachineOperatorReducer reducer(&R.graph_reducer, &R.jsgraph);
    Reduction reduction = reducer.Reduce(load);
    CHECK(!reduction.Changed());  // loads should not be reduced.
  }

  {
    Node* store =
        R.graph.NewNode(R.machine.Store(StoreRepresentation(
                            MachineRepresentation::kWord32, kNoWriteBarrier)),
                        base, index, load, load, R.graph.start());
    MachineOperatorReducer reducer(&R.graph_reducer, &R.jsgraph);
    Reduction reduction = reducer.Reduce(store);
    CHECK(!reduction.Changed());  // stores should not be reduced.
  }
}

TEST(ReduceFloat32Sub) {
  ReducerTester R;
  R.binop = R.machine.Float32Sub();

  FOR_FLOAT32_INPUTS(pl) {
    FOR_FLOAT32_INPUTS(pr) {
      float x = pl, y = pr;
      R.CheckFoldBinop<float>(x - y, x, y);
    }
  }

  Node* x = R.Parameter();
  Node* nan = R.Constant<float>(std::numeric_limits<float>::quiet_NaN());

  // nan - x  => nan
  R.CheckFoldBinop(std::numeric_limits<float>::quiet_NaN(), nan, x);
  // x - nan => nan
  R.CheckFoldBinop(std::numeric_limits<float>::quiet_NaN(), x, nan);
}

TEST(ReduceFloat64Sub) {
  ReducerTester R;
  R.binop = R.machine.Float64Sub();

  FOR_FLOAT64_INPUTS(pl) {
    FOR_FLOAT64_INPUTS(pr) {
      double x = pl, y = pr;
      R.CheckFoldBinop<double>(x - y, x, y);
    }
  }

  Node* x = R.Parameter();
  Node* nan = R.Constant<double>(std::numeric_limits<double>::quiet_NaN());

  // nan - x  => nan
  R.CheckFoldBinop(std::numeric_limits<double>::quiet_NaN(), nan, x);
  // x - nan => nan
  R.CheckFoldBinop(std::numeric_limits<double>::quiet_NaN(), x, nan);
}

// TODO(titzer): test MachineOperatorReducer for Word64And
// TODO(titzer): test MachineOperatorReducer for Word64Or
// TODO(titzer): test MachineOperatorReducer for Word64Xor
// TODO(titzer): test MachineOperatorReducer for Word64Equal
// TODO(titzer): test MachineOperatorReducer for Word64Not
// TODO(titzer): test MachineOperatorReducer for Int64Mul
// TODO(titzer): test MachineOperatorReducer for Int64UMul
// TODO(titzer): test MachineOperatorReducer for Int64Div
// TODO(titzer): test MachineOperatorReducer for Uint64Div
// TODO(titzer): test MachineOperatorReducer for Int64Mod
// TODO(titzer): test MachineOperatorReducer for Uint64Mod
// TODO(titzer): test MachineOperatorReducer for Int64Neg
// TODO(titzer): test MachineOperatorReducer for ChangeInt32ToFloat64
// TODO(titzer): test MachineOperatorReducer for ChangeFloat64ToInt32
// TODO(titzer): test MachineOperatorReducer for Float64Compare
// TODO(titzer): test MachineOperatorReducer for Float64Add
// TODO(titzer): test MachineOperatorReducer for Float64Sub
// TODO(titzer): test MachineOperatorReducer for Float64Mul
// TODO(titzer): test MachineOperatorReducer for Float64Div
// TODO(titzer): test MachineOperatorReducer for Float64Mod

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