DeadNodeEliminationTests.cpp

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/*
 * Copyright 2017 Nico Reißmann <nico.reissmann@gmail.com>
 * See COPYING for terms of redistribution.
 */
 
#include <gtest/gtest.h>
 
#include <jlm/llvm/ir/operators/alloca.hpp>
#include <jlm/llvm/ir/operators/delta.hpp>
#include <jlm/llvm/ir/operators/IntegerOperations.hpp>
#include <jlm/llvm/ir/operators/lambda.hpp>
#include <jlm/llvm/ir/operators/Load.hpp>
#include <jlm/llvm/ir/operators/MemoryStateOperations.hpp>
#include <jlm/llvm/ir/operators/Store.hpp>
#include <jlm/llvm/ir/RvsdgModule.hpp>
#include <jlm/llvm/opt/DeadNodeElimination.hpp>
#include <jlm/rvsdg/control.hpp>
#include <jlm/rvsdg/gamma.hpp>
#include <jlm/rvsdg/Phi.hpp>
#include <jlm/rvsdg/TestOperations.hpp>
#include <jlm/rvsdg/TestType.hpp>
#include <jlm/rvsdg/theta.hpp>
#include <jlm/rvsdg/view.hpp>
#include <jlm/util/Statistics.hpp>
 
static void
RunDeadNodeElimination(jlm::llvm::LlvmRvsdgModule & rvsdgModule)
{
  jlm::util::StatisticsCollector statisticsCollector;
  jlm::llvm::DeadNodeElimination deadNodeElimination;
  deadNodeElimination.Run(rvsdgModule, statisticsCollector);
}
 
TEST(DeadNodeEliminationTests, RootRegion)
{
  using namespace jlm::llvm;
 
  // Arrange
  LlvmRvsdgModule rvsdgModule(jlm::util::FilePath(""), "", "");
  auto & graph = rvsdgModule.Rvsdg();
 
  jlm::rvsdg::GraphImport::Create(graph, jlm::rvsdg::TestType::createValueType(), "x");
  auto y = &jlm::rvsdg::GraphImport::Create(graph, jlm::rvsdg::TestType::createValueType(), "y");
 
  jlm::rvsdg::GraphExport::Create(*y, "z");
  jlm::rvsdg::view(graph, stdout);
 
  // Act
  RunDeadNodeElimination(rvsdgModule);
  jlm::rvsdg::view(graph, stdout);
 
  // Assert
  EXPECT_EQ(graph.GetRootRegion().narguments(), 1u);
}
 
TEST(DeadNodeEliminationTests, Gamma1)
{
  using namespace jlm::llvm;
 
  // Arrange
  auto valueType = jlm::rvsdg::TestType::createValueType();
  auto controlType = jlm::rvsdg::ControlType::Create(2);
 
  LlvmRvsdgModule rvsdgModule(jlm::util::FilePath(""), "", "");
  auto & graph = rvsdgModule.Rvsdg();
  auto c = &jlm::rvsdg::GraphImport::Create(graph, controlType, "c");
  auto x = &jlm::rvsdg::GraphImport::Create(graph, valueType, "x");
  auto y = &jlm::rvsdg::GraphImport::Create(graph, valueType, "y");
 
  auto gamma = jlm::rvsdg::GammaNode::create(c, 2);
  auto ev1 = gamma->AddEntryVar(x);
  auto ev2 = gamma->AddEntryVar(y);
  auto ev3 = gamma->AddEntryVar(x);
 
  auto t = jlm::rvsdg::TestOperation::createNode(
               gamma->subregion(1),
               { ev2.branchArgument[1] },
               { valueType })
               ->output(0);
 
  gamma->AddExitVar(ev1.branchArgument);
  gamma->AddExitVar({ ev2.branchArgument[0], t });
  gamma->AddExitVar({ ev3.branchArgument[0], ev1.branchArgument[1] });
 
  jlm::rvsdg::GraphExport::Create(*gamma->output(0), "z");
  jlm::rvsdg::GraphExport::Create(*gamma->output(2), "w");
  jlm::rvsdg::view(graph, stdout);
 
  // Act
  RunDeadNodeElimination(rvsdgModule);
  jlm::rvsdg::view(graph, stdout);
 
  // Assert
  EXPECT_EQ(gamma->noutputs(), 2u);
  EXPECT_EQ(gamma->subregion(1)->numNodes(), 0u);
  EXPECT_EQ(gamma->subregion(1)->narguments(), 3u);
  EXPECT_EQ(gamma->ninputs(), 3u);
  EXPECT_EQ(graph.GetRootRegion().narguments(), 2u);
}
 
TEST(DeadNodeEliminationTests, Gamma2)
{
  using namespace jlm::llvm;
  using namespace jlm::rvsdg;
 
  // Arrange
  auto valueType = jlm::rvsdg::TestType::createValueType();
  auto controlType = jlm::rvsdg::ControlType::Create(2);
 
  jlm::llvm::LlvmRvsdgModule rvsdgModule(jlm::util::FilePath(""), "", "");
  auto & graph = rvsdgModule.Rvsdg();
  auto c = &jlm::rvsdg::GraphImport::Create(graph, controlType, "c");
  auto x = &jlm::rvsdg::GraphImport::Create(graph, valueType, "x");
 
  auto gamma = jlm::rvsdg::GammaNode::create(c, 2);
  gamma->AddEntryVar(x);
 
  auto n1 = TestOperation::createNode(gamma->subregion(0), {}, { valueType })->output(0);
  auto n2 = TestOperation::createNode(gamma->subregion(1), {}, { valueType })->output(0);
 
  gamma->AddExitVar({ n1, n2 });
 
  jlm::rvsdg::GraphExport::Create(*gamma->output(0), "x");
  jlm::rvsdg::view(graph, stdout);
 
  // Act
  RunDeadNodeElimination(rvsdgModule);
  jlm::rvsdg::view(graph, stdout);
 
  // Assert
  EXPECT_EQ(graph.GetRootRegion().narguments(), 1u);
}
 
TEST(DeadNodeEliminationTests, Theta)
{
  using namespace jlm::llvm;
  using namespace jlm::rvsdg;
 
  // Arrange
  auto valueType = jlm::rvsdg::TestType::createValueType();
  auto controlType = jlm::rvsdg::ControlType::Create(2);
 
  jlm::llvm::LlvmRvsdgModule rvsdgModule(jlm::util::FilePath(""), "", "");
  auto & graph = rvsdgModule.Rvsdg();
  auto x = &jlm::rvsdg::GraphImport::Create(graph, valueType, "x");
  auto y = &jlm::rvsdg::GraphImport::Create(graph, valueType, "y");
  auto z = &jlm::rvsdg::GraphImport::Create(graph, valueType, "z");
 
  auto theta = jlm::rvsdg::ThetaNode::create(&graph.GetRootRegion());
 
  auto lv1 = theta->AddLoopVar(x);
  auto lv2 = theta->AddLoopVar(y);
  auto lv3 = theta->AddLoopVar(z);
  auto lv4 = theta->AddLoopVar(y);
 
  lv1.post->divert_to(lv2.pre);
  lv2.post->divert_to(lv1.pre);
 
  auto t = TestOperation::createNode(theta->subregion(), { lv3.pre }, { valueType })->output(0);
  lv3.post->divert_to(t);
  lv4.post->divert_to(lv2.pre);
 
  auto c = TestOperation::createNode(theta->subregion(), {}, { controlType })->output(0);
  theta->set_predicate(c);
 
  jlm::rvsdg::GraphExport::Create(*lv1.output, "a");
  jlm::rvsdg::GraphExport::Create(*lv4.output, "b");
  jlm::rvsdg::view(graph, stdout);
 
  // Act
  RunDeadNodeElimination(rvsdgModule);
  jlm::rvsdg::view(graph, stdout);
 
  // Assert
  EXPECT_EQ(theta->noutputs(), 3u);
  EXPECT_EQ(theta->subregion()->numNodes(), 1u);
  EXPECT_EQ(graph.GetRootRegion().narguments(), 2u);
}
 
TEST(DeadNodeEliminationTests, NestedTheta)
{
  using namespace jlm::llvm;
 
  // Arrange
  auto valueType = jlm::rvsdg::TestType::createValueType();
  auto controlType = jlm::rvsdg::ControlType::Create(2);
 
  LlvmRvsdgModule rvsdgModule(jlm::util::FilePath(""), "", "");
  auto & graph = rvsdgModule.Rvsdg();
  auto c = &jlm::rvsdg::GraphImport::Create(graph, controlType, "c");
  auto x = &jlm::rvsdg::GraphImport::Create(graph, valueType, "x");
  auto y = &jlm::rvsdg::GraphImport::Create(graph, valueType, "y");
 
  auto outerTheta = jlm::rvsdg::ThetaNode::create(&graph.GetRootRegion());
 
  auto lvo1 = outerTheta->AddLoopVar(c);
  auto lvo2 = outerTheta->AddLoopVar(x);
  auto lvo3 = outerTheta->AddLoopVar(y);
 
  auto innerTheta = jlm::rvsdg::ThetaNode::create(outerTheta->subregion());
 
  auto lvi1 = innerTheta->AddLoopVar(lvo1.pre);
  auto lvi2 = innerTheta->AddLoopVar(lvo2.pre);
  auto lvi3 = innerTheta->AddLoopVar(lvo3.pre);
 
  lvi2.post->divert_to(lvi3.pre);
 
  innerTheta->set_predicate(lvi1.pre);
 
  lvo2.post->divert_to(lvi2.output);
  lvo3.post->divert_to(lvi2.output);
 
  outerTheta->set_predicate(lvo1.pre);
 
  jlm::rvsdg::GraphExport::Create(*lvo3.output, "y");
  jlm::rvsdg::view(graph, stdout);
 
  // Act
  RunDeadNodeElimination(rvsdgModule);
  jlm::rvsdg::view(graph, stdout);
 
  // Assert
  EXPECT_EQ(outerTheta->noutputs(), 3u);
}
 
TEST(DeadNodeEliminationTests, EvolvingTheta)
{
  using namespace jlm::llvm;
 
  // Arrange
  auto valueType = jlm::rvsdg::TestType::createValueType();
  auto controlType = jlm::rvsdg::ControlType::Create(2);
 
  LlvmRvsdgModule rvsdgModule(jlm::util::FilePath(""), "", "");
  auto & graph = rvsdgModule.Rvsdg();
  auto c = &jlm::rvsdg::GraphImport::Create(graph, controlType, "c");
  auto x1 = &jlm::rvsdg::GraphImport::Create(graph, valueType, "x1");
  auto x2 = &jlm::rvsdg::GraphImport::Create(graph, valueType, "x2");
  auto x3 = &jlm::rvsdg::GraphImport::Create(graph, valueType, "x3");
  auto x4 = &jlm::rvsdg::GraphImport::Create(graph, valueType, "x4");
 
  auto theta = jlm::rvsdg::ThetaNode::create(&graph.GetRootRegion());
 
  auto lv0 = theta->AddLoopVar(c);
  auto lv1 = theta->AddLoopVar(x1);
  auto lv2 = theta->AddLoopVar(x2);
  auto lv3 = theta->AddLoopVar(x3);
  auto lv4 = theta->AddLoopVar(x4);
 
  lv1.post->divert_to(lv2.pre);
  lv2.post->divert_to(lv3.pre);
  lv3.post->divert_to(lv4.pre);
 
  theta->set_predicate(lv0.pre);
 
  jlm::rvsdg::GraphExport::Create(*lv1.output, "x1");
  jlm::rvsdg::view(graph, stdout);
 
  // Act
  RunDeadNodeElimination(rvsdgModule);
  jlm::rvsdg::view(graph, stdout);
 
  // Assert
  EXPECT_EQ(theta->noutputs(), 5u);
}
 
TEST(DeadNodeEliminationTests, Lambda)
{
  using namespace jlm::llvm;
  using namespace jlm::rvsdg;
 
  // Arrange
  auto valueType = jlm::rvsdg::TestType::createValueType();
 
  jlm::llvm::LlvmRvsdgModule rvsdgModule(jlm::util::FilePath(""), "", "");
  auto & graph = rvsdgModule.Rvsdg();
  auto x = &jlm::rvsdg::GraphImport::Create(graph, valueType, "x");
  auto y = &jlm::rvsdg::GraphImport::Create(graph, valueType, "y");
 
  auto lambda = jlm::rvsdg::LambdaNode::Create(
      graph.GetRootRegion(),
      LlvmLambdaOperation::Create(
          jlm::rvsdg::FunctionType::Create({ valueType }, { valueType, valueType }),
          "f",
          Linkage::externalLinkage));
 
  auto cv1 = lambda->AddContextVar(*x).inner;
  auto cv2 = lambda->AddContextVar(*y).inner;
  TestOperation::createNode(
      lambda->subregion(),
      { lambda->GetFunctionArguments()[0], cv1 },
      { valueType });
 
  auto output = lambda->finalize({ lambda->GetFunctionArguments()[0], cv2 });
 
  jlm::rvsdg::GraphExport::Create(*output, "f");
  jlm::rvsdg::view(graph, stdout);
 
  // Act
  RunDeadNodeElimination(rvsdgModule);
  jlm::rvsdg::view(graph, stdout);
 
  // Assert
  EXPECT_EQ(lambda->subregion()->numNodes(), 0u);
  EXPECT_EQ(graph.GetRootRegion().narguments(), 1u);
}
 
TEST(DeadNodeEliminationTests, Phi)
{
  using namespace jlm::llvm;
  using namespace jlm::rvsdg;
 
  // Arrange
  auto valueType = TestType::createValueType();
  auto functionType = FunctionType::Create({ valueType }, { valueType });
 
  jlm::llvm::LlvmRvsdgModule rvsdgModule(jlm::util::FilePath(""), "", "");
  auto & rvsdg = rvsdgModule.Rvsdg();
  auto x = &jlm::rvsdg::GraphImport::Create(rvsdg, valueType, "x");
  auto y = &jlm::rvsdg::GraphImport::Create(rvsdg, valueType, "y");
  auto z = &jlm::rvsdg::GraphImport::Create(rvsdg, valueType, "z");
 
  auto setupF1 = [&](Region & region, Output & rv2, Output & dx)
  {
    auto lambda1 = jlm::rvsdg::LambdaNode::Create(
        region,
        LlvmLambdaOperation::Create(functionType, "f1", Linkage::externalLinkage));
    auto f2Argument = lambda1->AddContextVar(rv2).inner;
    auto xArgument = lambda1->AddContextVar(dx).inner;
 
    auto result =
        jlm::rvsdg::CreateOpNode<TestOperation>(
            { lambda1->GetFunctionArguments()[0], f2Argument, xArgument },
            std::vector<std::shared_ptr<const Type>>{ valueType, functionType, valueType },
            std::vector<std::shared_ptr<const Type>>{ valueType })
            .output(0);
 
    return lambda1->finalize({ result });
  };
 
  auto setupF2 = [&](Region & region, Output & rv1, Output & dy)
  {
    auto lambda2 = jlm::rvsdg::LambdaNode::Create(
        region,
        LlvmLambdaOperation::Create(functionType, "f2", Linkage::externalLinkage));
    auto f1Argument = lambda2->AddContextVar(rv1).inner;
    lambda2->AddContextVar(dy);
 
    auto result = jlm::rvsdg::CreateOpNode<TestOperation>(
                      { lambda2->GetFunctionArguments()[0], f1Argument },
                      std::vector<std::shared_ptr<const Type>>{ valueType, functionType },
                      std::vector<std::shared_ptr<const Type>>{ valueType })
                      .output(0);
 
    return lambda2->finalize({ result });
  };
 
  auto setupF3 = [&](Region & region, Output & dz)
  {
    auto lambda3 = jlm::rvsdg::LambdaNode::Create(
        region,
        LlvmLambdaOperation::Create(functionType, "f3", Linkage::externalLinkage));
    auto zArgument = lambda3->AddContextVar(dz).inner;
 
    auto result = jlm::rvsdg::CreateOpNode<TestOperation>(
                      { lambda3->GetFunctionArguments()[0], zArgument },
                      std::vector<std::shared_ptr<const Type>>{ valueType, valueType },
                      std::vector<std::shared_ptr<const Type>>{ valueType })
                      .output(0);
 
    return lambda3->finalize({ result });
  };
 
  auto setupF4 = [&](Region & region)
  {
    auto lambda = jlm::rvsdg::LambdaNode::Create(
        region,
        LlvmLambdaOperation::Create(functionType, "f4", Linkage::externalLinkage));
    return lambda->finalize({ lambda->GetFunctionArguments()[0] });
  };
 
  PhiBuilder phiBuilder;
  phiBuilder.begin(&rvsdg.GetRootRegion());
  auto & phiSubregion = *phiBuilder.subregion();
 
  auto rv1 = phiBuilder.AddFixVar(functionType);
  auto rv2 = phiBuilder.AddFixVar(functionType);
  auto rv3 = phiBuilder.AddFixVar(functionType);
  auto rv4 = phiBuilder.AddFixVar(functionType);
  auto dx = phiBuilder.AddContextVar(*x);
  auto dy = phiBuilder.AddContextVar(*y);
  auto dz = phiBuilder.AddContextVar(*z);
 
  auto f1 = setupF1(phiSubregion, *rv2.recref, *dx.inner);
  auto f2 = setupF2(phiSubregion, *rv1.recref, *dy.inner);
  auto f3 = setupF3(phiSubregion, *dz.inner);
  auto f4 = setupF4(phiSubregion);
 
  rv1.result->divert_to(f1);
  rv2.result->divert_to(f2);
  rv3.result->divert_to(f3);
  rv4.result->divert_to(f4);
  auto phiNode = phiBuilder.end();
 
  jlm::rvsdg::GraphExport::Create(*phiNode->output(0), "f1");
  jlm::rvsdg::GraphExport::Create(*phiNode->output(3), "f4");
  view(rvsdg, stdout);
 
  // Act
  RunDeadNodeElimination(rvsdgModule);
  view(rvsdg, stdout);
 
  // Assert
  EXPECT_EQ(phiNode->noutputs(), 3u); // f1, f2, and f4 are alive
  EXPECT_EQ(phiNode->output(0), rv1.output);
  EXPECT_EQ(phiNode->output(1), rv2.output);
  EXPECT_EQ(phiNode->output(2), rv4.output);
  EXPECT_EQ(phiSubregion.nresults(), 3u); // f1, f2, and f4 are alive
  EXPECT_EQ(phiSubregion.result(0), rv1.result);
  EXPECT_EQ(phiSubregion.result(1), rv2.result);
  EXPECT_EQ(phiSubregion.result(2), rv4.result);
  EXPECT_EQ(phiSubregion.narguments(), 4u); // f1, f2, f4, and dx are alive
  EXPECT_EQ(phiSubregion.argument(0), rv1.recref);
  EXPECT_EQ(phiSubregion.argument(1), rv2.recref);
  EXPECT_EQ(phiSubregion.argument(2), rv4.recref);
  EXPECT_EQ(phiSubregion.argument(3), dx.inner);
  EXPECT_EQ(phiNode->ninputs(), 1u); // dx is alive
  EXPECT_EQ(phiNode->input(0), dx.input);
}
 
TEST(DeadNodeEliminationTests, Delta)
{
  using namespace jlm::llvm;
  using namespace jlm::rvsdg;
 
  // Arrange
  auto valueType = TestType::createValueType();
 
  jlm::llvm::LlvmRvsdgModule rvsdgModule(jlm::util::FilePath(""), "", "");
  auto & rvsdg = rvsdgModule.Rvsdg();
 
  auto x = &jlm::rvsdg::GraphImport::Create(rvsdg, valueType, "x");
  auto y = &jlm::rvsdg::GraphImport::Create(rvsdg, valueType, "y");
  auto z = &jlm::rvsdg::GraphImport::Create(rvsdg, valueType, "z");
 
  auto deltaNode = jlm::rvsdg::DeltaNode::Create(
      &rvsdg.GetRootRegion(),
      jlm::llvm::DeltaOperation::Create(
          valueType,
          "delta",
          Linkage::externalLinkage,
          "",
          false,
          4));
 
  auto xArgument = deltaNode->AddContextVar(*x).inner;
  deltaNode->AddContextVar(*y);
  auto zArgument = deltaNode->AddContextVar(*z).inner;
 
  auto result = jlm::rvsdg::CreateOpNode<TestOperation>(
                    { xArgument },
                    std::vector<std::shared_ptr<const Type>>{ valueType },
                    std::vector<std::shared_ptr<const Type>>{ valueType })
                    .output(0);
 
  jlm::rvsdg::CreateOpNode<TestOperation>(
      { zArgument },
      std::vector<std::shared_ptr<const Type>>{ valueType },
      std::vector<std::shared_ptr<const Type>>{ valueType });
 
  auto deltaOutput = &deltaNode->finalize(result);
  jlm::rvsdg::GraphExport::Create(*deltaOutput, "");
  view(rvsdg, stdout);
 
  // Act
  RunDeadNodeElimination(rvsdgModule);
  view(rvsdg, stdout);
 
  // Assert
  EXPECT_EQ(deltaNode->subregion()->numNodes(), 1u);
  EXPECT_EQ(deltaNode->ninputs(), 1u);
}
 
TEST(DeadNodeEliminationTests, LoadNodes)
{
  using namespace jlm::llvm;
  using namespace jlm::rvsdg;
 
  // Arrange
  const auto pointerType = PointerType::Create();
  const auto memoryStateType = MemoryStateType::Create();
  const auto valueType = TestType::createValueType();
 
  LlvmRvsdgModule rvsdgModule(jlm::util::FilePath(""), "", "");
  auto & rvsdg = rvsdgModule.Rvsdg();
 
  auto lambdaNode = LambdaNode::Create(
      rvsdg.GetRootRegion(),
      LlvmLambdaOperation::Create(
          FunctionType::Create({ pointerType, memoryStateType }, { memoryStateType }),
          "f",
          Linkage::externalLinkage));
  auto addressArgument = lambdaNode->GetFunctionArguments()[0];
  auto memoryStateArgument = lambdaNode->GetFunctionArguments()[1];
 
  auto & oneNode = IntegerConstantOperation::Create(*lambdaNode->subregion(), 32, 1);
  auto allocaResults = AllocaOperation::create(pointerType, oneNode.output(0), 4);
 
  auto & storeNode = StoreNonVolatileOperation::CreateNode(
      *allocaResults[0],
      *addressArgument,
      { allocaResults[1] },
      4);
 
  auto & allocaLoadNode = LoadNonVolatileOperation::CreateNode(
      *allocaResults[0],
      { storeNode.output(0) },
      pointerType,
      4);
 
  auto & loadNode = LoadNonVolatileOperation::CreateNode(
      *allocaLoadNode.output(0),
      { memoryStateArgument },
      valueType,
      4);
 
  auto & lambdaExitMergeNode = LambdaExitMemoryStateMergeOperation::CreateNode(
      *lambdaNode->subregion(),
      { allocaLoadNode.output(1), loadNode.output(1) },
      { 0, 1 });
 
  auto lambdaOutput = lambdaNode->finalize({ lambdaExitMergeNode.output(0) });
  GraphExport::Create(*lambdaOutput, "f");
 
  view(rvsdg, stdout);
 
  // Act
  RunDeadNodeElimination(rvsdgModule);
  view(rvsdg, stdout);
 
  // Assert
  // We expect that both load nodes have been removed.
  EXPECT_FALSE(
      Region::ContainsOperation<LoadNonVolatileOperation>(*lambdaNode->subregion(), false));
  EXPECT_EQ(lambdaNode->subregion()->numNodes(), 4u);
}