text: /* 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/hlo_constant_folding.h"
  
  #include <memory>
  #include <utility>
  #include <vector>
  
  #include "tensorflow/compiler/xla/layout_util.h"
  #include "tensorflow/compiler/xla/literal.h"
  #include "tensorflow/compiler/xla/permutation_util.h"
  #include "tensorflow/compiler/xla/service/hlo_computation.h"
  #include "tensorflow/compiler/xla/service/hlo_instruction.h"
  #include "tensorflow/compiler/xla/service/hlo_opcode.h"
  #include "tensorflow/compiler/xla/service/hlo_parser.h"
  #include "tensorflow/compiler/xla/service/hlo_pass_fix.h"
  #include "tensorflow/compiler/xla/service/pattern_matcher.h"
  #include "tensorflow/compiler/xla/service/pattern_matcher_gmock.h"
  #include "tensorflow/compiler/xla/shape_util.h"
  #include "tensorflow/compiler/xla/test.h"
  #include "tensorflow/compiler/xla/tests/hlo_test_base.h"
  #include "tensorflow/compiler/xla/tests/literal_test_util.h"
  #include "tensorflow/compiler/xla/types.h"
  
  namespace xla {
  namespace {
  
  namespace m = xla::match;
  
  using HloConstantFoldingTest = HloTestBase;
  
  TEST_F(HloConstantFoldingTest, ConvertF32ToS64) {
    HloComputation::Builder builder(TestName());
    HloInstruction* input = builder.AddInstruction(
        HloInstruction::CreateConstant(LiteralUtil::CreateR0<float>(42.0f)));
    builder.AddInstruction(
        HloInstruction::CreateConvert(ShapeUtil::MakeShape(S64, {}), input));
  
    auto module = CreateNewVerifiedModule();
    auto computation = module->AddEntryComputation(builder.Build());
  
    EXPECT_THAT(computation->root_instruction(),
                GmockMatch(m::Convert().WithOperand(0, m::Op().Is(input))));
  
    HloConstantFolding const_folder;
    TF_ASSERT_OK_AND_ASSIGN(bool result, const_folder.Run(module.get()));
    EXPECT_TRUE(result);
  
    EXPECT_THAT(computation->root_instruction(), GmockMatch(m::Constant()));
    EXPECT_EQ(
        computation->root_instruction()->literal().GetFirstElement<int64_t>(),
        42);
  }
  
  TEST_F(HloConstantFoldingTest, ConvertS64ToF32) {
    HloComputation::Builder builder(TestName());
    HloInstruction* input = builder.AddInstruction(
        HloInstruction::CreateConstant(LiteralUtil::CreateR0<int64_t>(42)));
    builder.AddInstruction(
        HloInstruction::CreateConvert(ShapeUtil::MakeShape(F32, {}), input));
  
    auto module = CreateNewVerifiedModule();
    auto computation = module->AddEntryComputation(builder.Build());
  
    EXPECT_THAT(computation->root_instruction(),
                GmockMatch(m::Convert().WithOperand(0, m::Op().Is(input))));
  
    HloConstantFolding const_folder;
    TF_ASSERT_OK_AND_ASSIGN(bool result, const_folder.Run(module.get()));
    EXPECT_TRUE(result);
  
    EXPECT_THAT(computation->root_instruction(), GmockMatch(m::Constant()));
    EXPECT_EQ(computation->root_instruction()->literal().GetFirstElement<float>(),
              42.0f);
  }
  
  TEST_F(HloConstantFoldingTest, ConvertF32ArrayToS64Array) {
    HloComputation::Builder builder(TestName());
    HloInstruction* input = builder.AddInstruction(HloInstruction::CreateConstant(
        LiteralUtil::CreateR1<float>({42.0f, 19.0f})));
    builder.AddInstruction(
        HloInstruction::CreateConvert(ShapeUtil::MakeShape(S64, {2}), input));
  
    auto module = CreateNewVerifiedModule();
    auto computation = module->AddEntryComputation(builder.Build());
  
    EXPECT_THAT(computation->root_instruction(),
                GmockMatch(m::Convert().WithOperand(0, m::Op().Is(input))));
  
    HloConstantFolding const_folder;
    TF_ASSERT_OK_AND_ASSIGN(bool result, const_folder.Run(module.get()));
    EXPECT_TRUE(result);
  
    EXPECT_THAT(computation->root_instruction(), GmockMatch(m::Constant()));
    EXPECT_EQ(computation->root_instruction()->literal().Get<int64_t>({0}), 42);
    EXPECT_EQ(computation->root_instruction()->literal().Get<int64_t>({1}), 19);
  }
  
  TEST_F(HloConstantFoldingTest, Concatenate) {
    const struct TestConfig {
      int concat_dimension;
      std::vector<int64_t> dimensions;
      std::vector<int64_t> concat_sizes;
    } test_configs[] = {
        {1, {11, 0, 7, 5, 9}, {2, 5, 7, 11}},
        {3, {1, 4, 17, 0, 8}, {1, 3, 9, 12}},
    };
  
    for (auto& test_config : test_configs) {
      HloComputation::Builder builder(TestName());
      std::vector<int64_t> dimensions(test_config.dimensions.begin(),
                                      test_config.dimensions.end());
      int64_t concat_size = 0;
      std::vector<HloInstruction*> operands;
      for (auto csize : test_config.concat_sizes) {
        dimensions[test_config.concat_dimension] = csize;
        concat_size += csize;
        auto literal = LiteralUtil::CreateFromDimensions(F32, dimensions);
        HloInstruction* insn = builder.AddInstruction(
            HloInstruction::CreateConstant(std::move(literal)));
        operands.push_back(insn);
      }
      dimensions[test_config.concat_dimension] = concat_size;
      Shape shape = ShapeUtil::MakeShape(F32, dimensions);
      builder.AddInstruction(HloInstruction::CreateConcatenate(
          shape, operands, test_config.concat_dimension));
      auto module = CreateNewVerifiedModule();
      auto computation = module->AddEntryComputation(builder.Build());
  
      HloConstantFolding const_folder;
      TF_ASSERT_OK_AND_ASSIGN(bool result, const_folder.Run(module.get()));
      EXPECT_TRUE(result);
  
      HloInstruction* root = computation->root_instruction();
      EXPECT_THAT(root, GmockMatch(m::Constant()));
      EXPECT_TRUE(ShapeUtil::Equal(root->shape(), shape));
    }
  }
  
  TEST_F(HloConstantFoldingTest, Slice) {
    HloComputation::Builder builder(TestName());
    const int64_t dimensions[] = {11, 8, 7, 5, 9};
    const int64_t slice_start[] = {4, 2, 3, 1, 5};
    const int64_t slice_limits[] = {10, 8, 6, 5, 9};
    const int64_t slice_strides[] = {1, 1, 1, 1, 1};
    TF_ASSERT_OK_AND_ASSIGN(auto literal,
                            LiteralUtil::CreateRandomLiteral<F32>(
                                ShapeUtil::MakeShape(F32, dimensions), 0.0, 1.0));
    HloInstruction* literal_instruction = builder.AddInstruction(
        HloInstruction::CreateConstant(std::move(literal)));
    Shape shape = ShapeUtil::MakeShape(F32, {6, 6, 3, 4, 4});
    builder.AddInstruction(HloInstruction::CreateSlice(
        shape, literal_instruction, slice_start, slice_limits, slice_strides));
    auto module = CreateNewVerifiedModule();
    auto computation = module->AddEntryComputation(builder.Build());
  
    HloConstantFolding const_folder;
    TF_ASSERT_OK_AND_ASSIGN(bool result, const_folder.Run(module.get()));
    EXPECT_TRUE(result);
  
    HloInstruction* root = computation->root_instruction();
    EXPECT_THAT(root, GmockMatch(m::Constant()));
    EXPECT_TRUE(ShapeUtil::Equal(root->shape(), shape));
  }
  
  TEST_F(HloConstantFoldingTest, TransposeConstantFold) {
    HloComputation::Builder builder(TestName());
    const int64_t dimensions[] = {11, 8, 7, 5, 9};
    TF_ASSERT_OK_AND_ASSIGN(auto literal,
                            LiteralUtil::CreateRandomLiteral<F32>(
                                ShapeUtil::MakeShape(F32, dimensions), 0.0, 1.0));
    auto literal_clone = literal.Clone();
    HloInstruction* literal_instruction = builder.AddInstruction(
        HloInstruction::CreateConstant(std::move(literal)));
    Shape shape = ShapeUtil::MakeShape(F32, {8, 7, 11, 9, 5});
    const int64_t permutation[] = {1, 2, 0, 4, 3};
    builder.AddInstruction(
        HloInstruction::CreateTranspose(shape, literal_instruction, permutation));
    auto module = CreateNewVerifiedModule();
    auto computation = module->AddEntryComputation(builder.Build());
  
    HloConstantFolding const_folder;
    TF_ASSERT_OK_AND_ASSIGN(bool result, const_folder.Run(module.get()));
    EXPECT_TRUE(result);
  
    HloInstruction* root = computation->root_instruction();
    EXPECT_THAT(root, GmockMatch(m::Constant()));
    EXPECT_TRUE(ShapeUtil::Compatible(root->shape(), shape));
  
    using NativeT = typename primitive_util::PrimitiveTypeToNative<F32>::type;
    bool matched = true;
    root->literal().EachCell<NativeT>(
        [&](absl::Span<const int64_t> indices, NativeT value) {
          std::vector<int64_t> rindexes = PermuteInverse(indices, permutation);
          matched = matched && (value == literal_clone.Get<NativeT>(rindexes));
        });
    EXPECT_TRUE(matched);
  }
  
  const char* const kConstantFoldReduce = R"(
    HloModule ConstantFoldReduce
  
    add {
      a = s32[] parameter(0)
      b = s32[] parameter(1)
      ROOT add = s32[] add(a, b)
    }
  
    ENTRY r {
      x = s32[3] constant({1, 2, 3})
      init = s32[] constant(0)
      ROOT reduce = s32[] reduce(x, init), dimensions={0}, to_apply=add
    })";
  
  TEST_F(HloConstantFoldingTest, ConstantFoldReduce) {
    TF_ASSERT_OK_AND_ASSIGN(auto m,
                            ParseAndReturnVerifiedModule(kConstantFoldReduce));
    HloConstantFolding const_folder;
    TF_ASSERT_OK_AND_ASSIGN(bool result, const_folder.Run(m.get()));
    EXPECT_TRUE(result);
  
    EXPECT_EQ(6, m->entry_computation()
                     ->root_instruction()
                     ->literal()
                     .GetFirstElement<int32>());
  }
  
  TEST_F(HloConstantFoldingTest, ConstantFoldReduceNoLayout) {
    TF_ASSERT_OK_AND_ASSIGN(auto m,
                            ParseAndReturnVerifiedModule(kConstantFoldReduce));
    HloInstruction* add = m->computations().begin()->root_instruction();
    LayoutUtil::ClearLayout(add->mutable_shape());
    HloConstantFolding const_folder;
    TF_ASSERT_OK_AND_ASSIGN(bool result, const_folder.Run(m.get()));
    EXPECT_FALSE(result);
  
    EXPECT_THAT(m->entry_computation()->root_instruction(),
                GmockMatch(m::Reduce()));
  }
  
  const char* const kConstantFoldLargePad = R"(
    HloModule ConstantFoldLargePad
  
    ENTRY r {
      a = f32[1,1,1] constant({{{7}}})
      b = f32[] constant(42)
      ROOT pad = f32[2048,2048,128] pad(a, b), padding=1024_1023x1024_1023x64_63
    })";
  
  TEST_F(HloConstantFoldingTest, DoesNotFoldLargePad) {
    TF_ASSERT_OK_AND_ASSIGN(auto module,
                            ParseAndReturnVerifiedModule(kConstantFoldLargePad));
    HloConstantFolding const_folder;
    TF_ASSERT_OK_AND_ASSIGN(bool result, const_folder.Run(module.get()));
    EXPECT_FALSE(result);
  
    EXPECT_THAT(module->entry_computation()->root_instruction(),
                GmockMatch(m::Pad(m::Constant(), m::Constant())));
  }
  
  TEST_F(HloConstantFoldingTest, DontFoldSubcomputationContainingAfterAll) {
    const char* const kModuleStr = R"(
    HloModule test
  
    Fn {
      tok = token[] after-all()
      ROOT root = f32[10] iota(), iota_dimension=0
    }
  
    ENTRY entry {
      ROOT call = f32[10] call(), to_apply=Fn
    })";
    TF_ASSERT_OK_AND_ASSIGN(auto module,
                            ParseAndReturnVerifiedModule(kModuleStr));
    HloConstantFolding constant_folding;
    TF_ASSERT_OK_AND_ASSIGN(bool result,
                            RunHloPass(&constant_folding, module.get()));
    EXPECT_FALSE(result);
  }
  
  TEST_F(HloConstantFoldingTest,
         DontFoldSubcomputationTransitivelyContainingRng) {
    const char* const kModuleStr = R"(
    HloModule test
  
    InnerFn {
      c0 = f32[] constant(0)
      c1 = f32[] constant(1)
      ROOT rng = f32[10] rng(c0, c1), distribution=rng_uniform
    }
  
    Fn {
      ROOT fusion = f32[10] fusion(), kind=kLoop, calls=InnerFn
    }
  
    ENTRY entry {
      ROOT call = f32[10] call(), to_apply=Fn
    })";
    TF_ASSERT_OK_AND_ASSIGN(auto module,
                            ParseAndReturnVerifiedModule(kModuleStr));
    HloConstantFolding constant_folding;
    TF_ASSERT_OK_AND_ASSIGN(bool result,
                            RunHloPass(&constant_folding, module.get()));
    EXPECT_FALSE(result);
  }
  
  }  // namespace
  }  // namespace xla
  