/* Copyright 2017 The TensorFlow Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
==============================================================================*/

#include "tensorflow/compiler/xla/service/while_loop_invariant_code_motion.h"

#include "tensorflow/compiler/xla/service/hlo_matchers.h"
#include "tensorflow/compiler/xla/service/hlo_parser.h"
#include "tensorflow/compiler/xla/test.h"
#include "tensorflow/compiler/xla/tests/hlo_test_base.h"
#include "tensorflow/core/lib/core/status_test_util.h"

namespace xla {
namespace {

namespace op = xla::testing::opcode_matchers;

class WhileLoopInvariantCodeMotionTest : public HloTestBase {
 public:
  // Makes a computation which has one parameter, of the given shape, and always
  // returns PRED[]{true}.  This is useful as a dummy loop condition.
  HloComputation* MakeAlwaysTrueComputation(const Shape& param_shape,
                                            HloModule* module);
};

static void FindOnlyWhileInstruction(HloComputation* computation,
                                     HloInstruction** while_instruction) {
  *while_instruction = nullptr;
  for (auto* instr : computation->instructions()) {
    if (instr->opcode() == HloOpcode::kWhile) {
      ASSERT_EQ(*while_instruction, nullptr);
      *while_instruction = instr;
    }
  }

  ASSERT_NE(*while_instruction, nullptr);
}

HloComputation* WhileLoopInvariantCodeMotionTest::MakeAlwaysTrueComputation(
    const Shape& param_shape, HloModule* module) {
  HloComputation::Builder builder(TestName() + ".always_true");
  builder.AddInstruction(
      HloInstruction::CreateParameter(0, param_shape, "param"));
  builder.AddInstruction(
      HloInstruction::CreateConstant(LiteralUtil::CreateR0<bool>(true)));
  return module->AddEmbeddedComputation(builder.Build());
}

TEST_F(WhileLoopInvariantCodeMotionTest, HoistOneInvariantOperation) {
  auto m = CreateNewVerifiedModule();
  auto scalar_s32 = ShapeUtil::MakeShape(S32, {});
  Shape while_shape =
      ShapeUtil::MakeTupleShape({scalar_s32, scalar_s32, scalar_s32});

  HloComputation* while_body = [&]() {
    HloComputation::Builder builder(TestName() + ".while_body");
    HloInstruction* param = builder.AddInstruction(
        HloInstruction::CreateParameter(0, while_shape, "param"));
    HloInstruction* gte_0 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 0));
    HloInstruction* gte_1 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 1));
    HloInstruction* add_result =
        builder.AddInstruction(HloInstruction::CreateBinary(
            scalar_s32, HloOpcode::kAdd, gte_0, gte_1));
    builder.AddInstruction(
        HloInstruction::CreateTuple({gte_0, gte_1, add_result}));

    return m->AddEmbeddedComputation(builder.Build());
  }();

  HloComputation::Builder builder(TestName());
  auto* init_value = builder.AddInstruction(
      HloInstruction::CreateParameter(0, while_shape, "init_value"));
  builder.AddInstruction(HloInstruction::CreateWhile(
      while_shape, MakeAlwaysTrueComputation(while_shape, m.get()), while_body,
      init_value));
  HloComputation* entry_computation = m->AddEntryComputation(builder.Build());
  TF_ASSERT_OK_AND_ASSIGN(bool simplified_loop,
                          WhileLoopInvariantCodeMotion{}.Run(m.get()));
  EXPECT_TRUE(simplified_loop);

  HloInstruction* transformed_while;
  FindOnlyWhileInstruction(entry_computation, &transformed_while);

  EXPECT_THAT(entry_computation->instructions(), Contains(op::Add()));
  EXPECT_THAT(transformed_while->while_body()->instructions(),
              Each(Not(op::Add())));
}

TEST_F(WhileLoopInvariantCodeMotionTest, HoistInvariantOperationTree) {
  auto m = CreateNewVerifiedModule();
  auto scalar_s32 = ShapeUtil::MakeShape(S32, {});
  Shape while_shape =
      ShapeUtil::MakeTupleShape({scalar_s32, scalar_s32, scalar_s32});

  HloComputation* while_body = [&]() {
    HloComputation::Builder builder(TestName() + ".while_body");
    HloInstruction* param = builder.AddInstruction(
        HloInstruction::CreateParameter(0, while_shape, "param"));
    HloInstruction* gte_0 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 0));
    HloInstruction* gte_1 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 1));
    HloInstruction* gte_2_loop_variant = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 2));

    HloInstruction* add_result =
        builder.AddInstruction(HloInstruction::CreateBinary(
            scalar_s32, HloOpcode::kAdd, gte_0, gte_1));
    HloInstruction* mul_result =
        builder.AddInstruction(HloInstruction::CreateBinary(
            scalar_s32, HloOpcode::kMultiply, add_result, gte_1));
    HloInstruction* negate_result =
        builder.AddInstruction(HloInstruction::CreateUnary(
            scalar_s32, HloOpcode::kNegate, mul_result));
    HloInstruction* constant = builder.AddInstruction(
        HloInstruction::CreateConstant(LiteralUtil::CreateR0<int32>(4)));
    HloInstruction* sub_result =
        builder.AddInstruction(HloInstruction::CreateBinary(
            scalar_s32, HloOpcode::kSubtract, negate_result, constant));
    HloInstruction* divide_result =
        builder.AddInstruction(HloInstruction::CreateBinary(
            scalar_s32, HloOpcode::kDivide, sub_result, gte_2_loop_variant));
    builder.AddInstruction(
        HloInstruction::CreateTuple({gte_0, gte_1, divide_result}));

    return m->AddEmbeddedComputation(builder.Build());
  }();

  HloComputation::Builder builder(TestName());
  auto* init_value = builder.AddInstruction(
      HloInstruction::CreateParameter(0, while_shape, "init_value"));
  builder.AddInstruction(HloInstruction::CreateWhile(
      while_shape, MakeAlwaysTrueComputation(while_shape, m.get()), while_body,
      init_value));
  HloComputation* entry_computation = m->AddEntryComputation(builder.Build());
  TF_ASSERT_OK_AND_ASSIGN(bool simplified_loop,
                          WhileLoopInvariantCodeMotion{}.Run(m.get()));
  EXPECT_TRUE(simplified_loop);

  HloInstruction* transformed_while;
  FindOnlyWhileInstruction(entry_computation, &transformed_while);

  EXPECT_THAT(entry_computation->instructions(),
              AllOf(Contains(op::Add()), Contains(op::Multiply()),
                    Contains(op::Negate()), Contains(op::Subtract()),
                    Contains(op::Constant()),

                    // The division had a loop varying operand so that better
                    // not be hoisted.
                    Not(Contains(op::Divide()))));

  EXPECT_THAT(transformed_while->while_body()->instructions(),
              Each(Not(AnyOf(op::Add(), op::Multiply(), op::Negate(),
                             op::Subtract(), op::Constant()))));

  EXPECT_THAT(transformed_while->while_body()->instructions(),
              Contains(op::Divide()));
}

TEST_F(WhileLoopInvariantCodeMotionTest,
       DontHoistTriviallyLoopVaryingComputation) {
  // Basic negative test: the add expression is not loop invariant.
  auto m = CreateNewVerifiedModule();
  auto scalar_s32 = ShapeUtil::MakeShape(S32, {});
  Shape while_shape = ShapeUtil::MakeTupleShape({scalar_s32, scalar_s32});

  HloComputation* while_body = [&]() {
    HloComputation::Builder builder(TestName() + ".while_body");
    HloInstruction* param = builder.AddInstruction(
        HloInstruction::CreateParameter(0, while_shape, "param"));
    HloInstruction* gte_0 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 0));
    HloInstruction* gte_1 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 1));
    HloInstruction* add_result =
        builder.AddInstruction(HloInstruction::CreateBinary(
            scalar_s32, HloOpcode::kAdd, gte_0, gte_1));
    builder.AddInstruction(HloInstruction::CreateTuple({gte_0, add_result}));

    return m->AddEmbeddedComputation(builder.Build());
  }();

  HloComputation::Builder builder(TestName());
  auto* init_value = builder.AddInstruction(
      HloInstruction::CreateParameter(0, while_shape, "init_value"));
  auto* while_inst = builder.AddInstruction(HloInstruction::CreateWhile(
      while_shape, MakeAlwaysTrueComputation(while_shape, m.get()), while_body,
      init_value));

  m->AddEntryComputation(builder.Build());

  TF_ASSERT_OK_AND_ASSIGN(bool simplified_loop,
                          WhileLoopInvariantCodeMotion{}.Run(m.get()));
  EXPECT_FALSE(simplified_loop);

  EXPECT_THAT(while_inst->while_body()->instructions(), Contains(op::Add()));
}

TEST_F(WhileLoopInvariantCodeMotionTest,
       DontHoistLoopVaryingComputationWithAlternatingTuples) {
  auto m = CreateNewVerifiedModule();
  auto scalar_s32 = ShapeUtil::MakeShape(S32, {});
  Shape while_shape =
      ShapeUtil::MakeTupleShape({scalar_s32, scalar_s32, scalar_s32});

  HloComputation* while_body = [&]() {
    HloComputation::Builder builder(TestName() + ".while_body");
    HloInstruction* param = builder.AddInstruction(
        HloInstruction::CreateParameter(0, while_shape, "param"));
    HloInstruction* gte_0 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 0));
    HloInstruction* gte_1 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 1));
    HloInstruction* add_result =
        builder.AddInstruction(HloInstruction::CreateBinary(
            scalar_s32, HloOpcode::kAdd, gte_0, gte_1));
    builder.AddInstruction(
        HloInstruction::CreateTuple({gte_1, gte_0, add_result}));

    return m->AddEmbeddedComputation(builder.Build());
  }();

  HloComputation::Builder builder(TestName());
  auto* init_value = builder.AddInstruction(
      HloInstruction::CreateParameter(0, while_shape, "init_value"));
  auto* while_inst = builder.AddInstruction(HloInstruction::CreateWhile(
      while_shape, MakeAlwaysTrueComputation(while_shape, m.get()), while_body,
      init_value));

  m->AddEntryComputation(builder.Build());
  TF_ASSERT_OK_AND_ASSIGN(bool simplified_loop,
                          WhileLoopInvariantCodeMotion{}.Run(m.get()));
  EXPECT_FALSE(simplified_loop);

  EXPECT_THAT(while_inst->while_body()->instructions(), Contains(op::Add()));
}

TEST_F(WhileLoopInvariantCodeMotionTest, DontHoistInstructionWithSideEffects) {
  auto m = CreateNewVerifiedModule();
  auto scalar_s32 = ShapeUtil::MakeShape(S32, {});
  auto token_shape = ShapeUtil::MakeTokenShape();
  Shape while_shape =
      ShapeUtil::MakeTupleShape({scalar_s32, scalar_s32, token_shape});

  HloComputation* while_body = [&]() {
    HloComputation::Builder builder(TestName() + ".while_body");
    HloInstruction* param = builder.AddInstruction(
        HloInstruction::CreateParameter(0, while_shape, "param"));
    HloInstruction* gte_0 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 0));
    HloInstruction* gte_1 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 1));
    HloInstruction* in_token = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(token_shape, param, 2));
    HloInstruction* out_token = builder.AddInstruction(
        HloInstruction::CreateOutfeed(scalar_s32, gte_0, in_token, ""));
    builder.AddInstruction(
        HloInstruction::CreateTuple({gte_0, gte_1, out_token}));

    return m->AddEmbeddedComputation(builder.Build());
  }();

  HloComputation::Builder builder(TestName());
  auto* scalar_param = builder.AddInstruction(
      HloInstruction::CreateParameter(0, scalar_s32, "param"));
  auto* token = builder.AddInstruction(HloInstruction::CreateToken());
  auto* init_value = builder.AddInstruction(
      HloInstruction::CreateTuple({scalar_param, scalar_param, token}));
  auto* while_inst = builder.AddInstruction(HloInstruction::CreateWhile(
      while_shape, MakeAlwaysTrueComputation(while_shape, m.get()), while_body,
      init_value));
  builder.AddInstruction(
      HloInstruction::CreateGetTupleElement(scalar_s32, while_inst, 0));
  m->AddEntryComputation(builder.Build());

  TF_ASSERT_OK_AND_ASSIGN(bool simplified_loop,
                          WhileLoopInvariantCodeMotion{}.Run(m.get()));
  ASSERT_FALSE(simplified_loop);

  EXPECT_THAT(while_inst->while_body()->instructions(),
              Contains(op::Outfeed()));
}

TEST_F(WhileLoopInvariantCodeMotionTest, DontHoistBitcastAlone) {
  // The bitcast's user, an outfeed, can't be hoisted, so don't hoist the
  // bitcast either.
  auto m = CreateNewVerifiedModule();
  auto scalar_s32 = ShapeUtil::MakeShape(S32, {});
  auto effective_scalar_s32 = ShapeUtil::MakeShape(S32, {1});
  auto token_shape = ShapeUtil::MakeTokenShape();
  Shape while_shape =
      ShapeUtil::MakeTupleShape({scalar_s32, scalar_s32, token_shape});

  HloComputation* while_body = [&]() {
    HloComputation::Builder builder(TestName() + ".while_body");
    HloInstruction* param = builder.AddInstruction(
        HloInstruction::CreateParameter(0, while_shape, "param"));
    HloInstruction* gte_0 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 0));
    HloInstruction* gte_1 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 1));
    HloInstruction* in_token = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(token_shape, param, 2));
    HloInstruction* bitcast_inst =
        builder.AddInstruction(HloInstruction::CreateUnary(
            effective_scalar_s32, HloOpcode::kBitcast, gte_0));
    HloInstruction* out_token =
        builder.AddInstruction(HloInstruction::CreateOutfeed(
            effective_scalar_s32, bitcast_inst, in_token, ""));
    builder.AddInstruction(
        HloInstruction::CreateTuple({gte_0, gte_1, out_token}));

    return m->AddEmbeddedComputation(builder.Build());
  }();

  HloComputation::Builder builder(TestName());
  auto* scalar_param = builder.AddInstruction(
      HloInstruction::CreateParameter(0, scalar_s32, "param"));
  auto* token = builder.AddInstruction(HloInstruction::CreateToken());
  auto* init_value = builder.AddInstruction(
      HloInstruction::CreateTuple({scalar_param, scalar_param, token}));
  auto* while_inst = builder.AddInstruction(HloInstruction::CreateWhile(
      while_shape, MakeAlwaysTrueComputation(while_shape, m.get()), while_body,
      init_value));
  builder.AddInstruction(
      HloInstruction::CreateGetTupleElement(scalar_s32, while_inst, 0));

  m->AddEntryComputation(builder.Build());

  TF_ASSERT_OK_AND_ASSIGN(bool simplified_loop,
                          WhileLoopInvariantCodeMotion{}.Run(m.get()));
  EXPECT_FALSE(simplified_loop);

  EXPECT_THAT(while_inst->while_body()->instructions(),
              Contains(op::Outfeed()));
  EXPECT_THAT(while_inst->while_body()->instructions(),
              Contains(op::Bitcast()));
}

TEST_F(WhileLoopInvariantCodeMotionTest, HoistBitcastIfNeeded) {
  // The bitcast's user can be hoisted, so hoist the bitcast too.
  auto m = CreateNewVerifiedModule();
  auto scalar_s32 = ShapeUtil::MakeShape(S32, {});
  auto effective_scalar_s32 = ShapeUtil::MakeShape(S32, {1});
  Shape while_shape = ShapeUtil::MakeTupleShape(
      {scalar_s32, effective_scalar_s32, effective_scalar_s32});

  HloComputation* while_body = [&]() {
    HloComputation::Builder builder(TestName() + ".while_body");
    HloInstruction* param = builder.AddInstruction(
        HloInstruction::CreateParameter(0, while_shape, "param"));
    HloInstruction* gte_0 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 0));
    HloInstruction* gte_1 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(effective_scalar_s32, param, 1));
    HloInstruction* bitcast_inst =
        builder.AddInstruction(HloInstruction::CreateUnary(
            effective_scalar_s32, HloOpcode::kBitcast, gte_0));
    HloInstruction* add_inst =
        builder.AddInstruction(HloInstruction::CreateBinary(
            effective_scalar_s32, HloOpcode::kAdd, bitcast_inst, gte_1));
    builder.AddInstruction(
        HloInstruction::CreateTuple({gte_0, gte_1, add_inst}));

    return m->AddEmbeddedComputation(builder.Build());
  }();

  HloComputation::Builder builder(TestName());
  auto* init_value = builder.AddInstruction(
      HloInstruction::CreateParameter(0, while_shape, "init_value"));
  builder.AddInstruction(HloInstruction::CreateWhile(
      while_shape, MakeAlwaysTrueComputation(while_shape, m.get()), while_body,
      init_value));

  HloComputation* entry_computation = m->AddEntryComputation(builder.Build());

  TF_ASSERT_OK_AND_ASSIGN(bool simplified_loop,
                          WhileLoopInvariantCodeMotion{}.Run(m.get()));
  EXPECT_TRUE(simplified_loop);

  HloInstruction* transformed_while;
  FindOnlyWhileInstruction(entry_computation, &transformed_while);

  EXPECT_THAT(transformed_while->while_body()->instructions(),
              Each(Not(op::Add())));
  EXPECT_THAT(transformed_while->while_body()->instructions(),
              Each(Not(op::Bitcast())));
  EXPECT_THAT(entry_computation->instructions(), Contains(op::Add()));
  EXPECT_THAT(entry_computation->instructions(), Contains(op::Bitcast()));
}

TEST_F(WhileLoopInvariantCodeMotionTest, DontHoistControlDependencies) {
  auto m = CreateNewVerifiedModule();
  auto scalar_s32 = ShapeUtil::MakeShape(S32, {});
  Shape while_shape =
      ShapeUtil::MakeTupleShape({scalar_s32, scalar_s32, scalar_s32});

  HloComputation* while_body;
  {
    HloComputation::Builder builder(TestName() + ".while_body");
    HloInstruction* param = builder.AddInstruction(
        HloInstruction::CreateParameter(0, while_shape, "param"));
    HloInstruction* gte_0 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 0));
    HloInstruction* gte_1 = builder.AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 1));
    HloInstruction* add_result =
        builder.AddInstruction(HloInstruction::CreateBinary(
            scalar_s32, HloOpcode::kAdd, gte_0, gte_1));
    TF_ASSERT_OK(param->AddControlDependencyTo(add_result));
    builder.AddInstruction(
        HloInstruction::CreateTuple({gte_0, gte_1, add_result}));

    while_body = m->AddEmbeddedComputation(builder.Build());
  }

  HloComputation::Builder builder(TestName());
  auto* init_value = builder.AddInstruction(
      HloInstruction::CreateParameter(0, while_shape, "init_value"));
  builder.AddInstruction(HloInstruction::CreateWhile(
      while_shape, MakeAlwaysTrueComputation(while_shape, m.get()), while_body,
      init_value));
  m->AddEntryComputation(builder.Build());
  TF_ASSERT_OK_AND_ASSIGN(bool simplified_loop,
                          WhileLoopInvariantCodeMotion{}.Run(m.get()));
  EXPECT_FALSE(simplified_loop);
}

TEST_F(WhileLoopInvariantCodeMotionTest, BodyHasNonTupleRoot) {
  auto m = CreateNewVerifiedModule();
  auto scalar_s32 = ShapeUtil::MakeShape(S32, {});
  Shape while_shape = ShapeUtil::MakeTupleShape({scalar_s32, scalar_s32});

  HloComputation* while_body = [&]() {
    HloComputation::Builder builder(TestName() + ".passthrough");
    HloInstruction* param = builder.AddInstruction(
        HloInstruction::CreateParameter(0, while_shape, "param"));
    HloComputation* result = m->AddEmbeddedComputation(builder.Build());

    result->AddInstruction(
        HloInstruction::CreateGetTupleElement(scalar_s32, param, 1));
    return result;
  }();

  HloComputation::Builder builder(TestName());
  auto* init_value = builder.AddInstruction(
      HloInstruction::CreateParameter(0, while_shape, "init_value"));
  builder.AddInstruction(HloInstruction::CreateWhile(
      while_shape, MakeAlwaysTrueComputation(while_shape, m.get()), while_body,
      init_value));
  m->AddEntryComputation(builder.Build());
  TF_ASSERT_OK_AND_ASSIGN(bool simplified_loop,
                          WhileLoopInvariantCodeMotion{}.Run(m.get()));
  EXPECT_FALSE(simplified_loop);
}

const char* const kConstantHoistingTestCase = R"(
HloModule ModuleWithWhile

body {
  p_body = (f32[2]{0}) parameter(0)
  p_body.1 = f32[2]{0} get-tuple-element(p_body), index=0
  const = f32[2]{0} constant({3, 4})
  add.0 = f32[2]{0} add(p_body.1, const)
  ROOT root = (f32[2]{0}) tuple(add.0)
}

condition {
  p_cond = (f32[2]{0}) parameter(0)
  ROOT result = pred[] constant(true)
}

ENTRY entry {
  const_0 = f32[2]{0} constant({1, 2})
  while_init = (f32[2]{0}) tuple(const_0)
  ROOT while = (f32[2]{0}) while(while_init), condition=condition, body=body
}
)";

TEST_F(WhileLoopInvariantCodeMotionTest, HoistsConstantWhenAsked) {
  auto m = ParseAndReturnVerifiedModule(kConstantHoistingTestCase).ValueOrDie();

  TF_ASSERT_OK_AND_ASSIGN(
      bool simplified_loop,
      WhileLoopInvariantCodeMotion{/*hoist_constants=*/true}.Run(m.get()));
  EXPECT_TRUE(simplified_loop);

  HloComputation* while_body = m->GetComputationWithName("wide.body");
  ASSERT_NE(while_body, nullptr);

  // We expect the while body to be the equivalent of:
  //
  //  wide.body {
  //    wide_param.1 = (f32[2]{0}, f32[2]{0}) parameter(0)
  //    get-tuple-element.1 = f32[2]{0} get-tuple-element(wide_param.1), index=0
  //    tuple.1 = (f32[2]{0}) tuple(get-tuple-element.1)
  //    get-tuple-element.4 = f32[2]{0} get-tuple-element(tuple.1), index=0
  //    get-tuple-element.7 = f32[2]{0} get-tuple-element(wide_param.1), index=1
  //    add.1 = f32[2]{0} add(get-tuple-element.4, get-tuple-element.7)
  //    tuple.3 = (f32[2]{0}) tuple(add.1)
  //    get-tuple-element.8 = f32[2]{0} get-tuple-element(tuple.3), index=0
  //    get-tuple-element.9 = f32[2]{0} get-tuple-element(wide_param.1), index=1
  //    ROOT tuple.4 = (f32[2]{0}, f32[2]{0}) tuple(get-tuple-element.8,
  //                                                get-tuple-element.9)
  //  }

  auto wide_param_1 = op::Parameter(0);
  auto get_tuple_element_1 = op::GetTupleElement(wide_param_1, 0);
  auto tuple_1 = op::Tuple(get_tuple_element_1);
  auto get_tuple_element_4 = op::GetTupleElement(tuple_1, 0);
  auto get_tuple_element_7 = op::GetTupleElement(wide_param_1, 1);
  auto add_1 = op::Add(get_tuple_element_4, get_tuple_element_7);
  auto tuple_3 = op::Tuple(add_1);
  auto get_tuple_element_8 = op::GetTupleElement(tuple_3, 0);
  auto get_tuple_element_9 = op::GetTupleElement(wide_param_1, 1);
  auto tuple_4 = op::Tuple(get_tuple_element_8, get_tuple_element_9);

  EXPECT_THAT(while_body->root_instruction(), tuple_4);
}

TEST_F(WhileLoopInvariantCodeMotionTest, DoesNotHoistConstantByDefault) {
  auto m = ParseAndReturnVerifiedModule(kConstantHoistingTestCase).ValueOrDie();

  TF_ASSERT_OK_AND_ASSIGN(bool simplified_loop,
                          WhileLoopInvariantCodeMotion{}.Run(m.get()));
  EXPECT_FALSE(simplified_loop);
}

TEST_F(WhileLoopInvariantCodeMotionTest, DoNotHoistOutOfSingleIteration) {
  const char* const kHloModule = R"(
    HloModule ModuleWithWhile

    body {
      p_body = (f32[2], f32[2], f32[2], s32[]) parameter(0)
      val.0 = f32[2] get-tuple-element(p_body), index=0
      val.1 = f32[2] get-tuple-element(p_body), index=1
      add = f32[2] add(val.0, val.1)
      const = s32[] constant(-1)
      ROOT root = (f32[2], f32[2], f32[2], s32[]) tuple(val.0, val.1, add, const)
    }

    condition {
      p_cond = (f32[2], f32[2], f32[2], s32[]) parameter(0)
      gte = s32[] get-tuple-element(p_cond), index=3
      const = s32[] constant(42)
      ROOT result = pred[] compare(gte, const), direction=EQ
    }

    ENTRY entry {
      param.0 = f32[2] parameter(0)
      param.1 = s32[] parameter(1)
      while_init = (f32[2], f32[2], f32[2], s32[]) tuple(param.0, param.0, param.0, param.1)
      ROOT while = (f32[2], f32[2], f32[2], s32[]) while(while_init), condition=condition, body=body
    })";
  TF_ASSERT_OK_AND_ASSIGN(std::unique_ptr<HloModule> module,
                          ParseAndReturnVerifiedModule(kHloModule));

  TF_ASSERT_OK_AND_ASSIGN(bool simplified_loop,
                          WhileLoopInvariantCodeMotion{}.Run(module.get()));
  EXPECT_FALSE(simplified_loop);
}

const char* const kInflatingTestCase = R"(
HloModule ModuleWithWhile

mul {
  lhs = f32[] parameter(0)
  rhs = f32[] parameter(1)
  ROOT mul = f32[] multiply(lhs, rhs)
}

body {
  p_body = (f32[]) parameter(0)
  iota = f32[1024, 1024] iota(), iota_dimension=0
  add = f32[1024, 1024] add(iota, iota)
  constant = f32[] constant(1.0)
  reduce = f32[] reduce(f32[1024, 1024] add, f32[] constant), dimensions={0,1}, to_apply=mul
  ROOT root = (f32[]) tuple(reduce)
}

condition {
  p_cond = (f32[]) parameter(0)
  ROOT result = pred[] constant(true)
}

ENTRY entry {
  param = f32[] parameter(0)
  while_init = (f32[]) tuple(param)
  ROOT while = (f32[]) while(while_init), condition=condition, body=body
}
)";

TEST_F(WhileLoopInvariantCodeMotionTest, HoistsInflatingByDefault) {
  auto m = ParseAndReturnVerifiedModule(kInflatingTestCase).ValueOrDie();

  TF_ASSERT_OK_AND_ASSIGN(
      bool simplified_loop,
      WhileLoopInvariantCodeMotion(/*hoist_constants=*/true).Run(m.get()));
  EXPECT_TRUE(simplified_loop);

  HloComputation* while_body = m->GetComputationWithName("wide.body");
  ASSERT_NE(while_body, nullptr);
  EXPECT_THAT(while_body->instructions(), Not(Contains(op::Iota())));
}

TEST_F(WhileLoopInvariantCodeMotionTest, NoHoistInflating) {
  auto m = ParseAndReturnVerifiedModule(kInflatingTestCase).ValueOrDie();

  TF_ASSERT_OK_AND_ASSIGN(
      bool simplified_loop,
      WhileLoopInvariantCodeMotion(/*hoist_constants=*/true,
                                   /*hoist_size_inflating_ops=*/false)
          .Run(m.get()));
  EXPECT_FALSE(simplified_loop);
}

}  // namespace
}  // namespace xla
