TheRock/compiler/amd-llvm/llvm/unittests/IR/ValueHandleTest.cpp

//===- ValueHandleTest.cpp - ValueHandle tests ----------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "llvm/IR/ValueHandle.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "gtest/gtest.h"
#include <memory>

using namespace llvm;

namespace {

class ValueHandle : public testing::Test {
protected:
  LLVMContext Context;
  Constant *ConstantV;
  std::unique_ptr<BitCastInst> BitcastV;

  ValueHandle()
      : ConstantV(ConstantInt::get(Type::getInt32Ty(Context), 0)),
        BitcastV(new BitCastInst(ConstantV, Type::getInt32Ty(Context))) {}
};

class ConcreteCallbackVH final : public CallbackVH {
public:
  ConcreteCallbackVH(Value *V) : CallbackVH(V) {}
};

TEST_F(ValueHandle, WeakVH_BasicOperation) {
  WeakVH WVH(BitcastV.get());
  EXPECT_EQ(BitcastV.get(), WVH);
  WVH = ConstantV;
  EXPECT_EQ(ConstantV, WVH);

  // Make sure I can call a method on the underlying Value.  It
  // doesn't matter which method.
  EXPECT_EQ(Type::getInt32Ty(Context), WVH->getType());
  EXPECT_EQ(Type::getInt32Ty(Context), (*WVH).getType());

  WVH = BitcastV.get();
  BitcastV->replaceAllUsesWith(ConstantV);
  EXPECT_EQ(WVH, BitcastV.get());
  BitcastV.reset();
  EXPECT_EQ(WVH, nullptr);
}

TEST_F(ValueHandle, WeakTrackingVH_BasicOperation) {
  WeakTrackingVH WVH(BitcastV.get());
  EXPECT_EQ(BitcastV.get(), WVH);
  WVH = ConstantV;
  EXPECT_EQ(ConstantV, WVH);

  // Make sure I can call a method on the underlying Value.  It
  // doesn't matter which method.
  EXPECT_EQ(Type::getInt32Ty(Context), WVH->getType());
  EXPECT_EQ(Type::getInt32Ty(Context), (*WVH).getType());
}

TEST_F(ValueHandle, WeakTrackingVH_Comparisons) {
  WeakTrackingVH BitcastWVH(BitcastV.get());
  WeakTrackingVH ConstantWVH(ConstantV);

  EXPECT_TRUE(BitcastWVH == BitcastWVH);
  EXPECT_TRUE(BitcastV.get() == BitcastWVH);
  EXPECT_TRUE(BitcastWVH == BitcastV.get());
  EXPECT_FALSE(BitcastWVH == ConstantWVH);

  EXPECT_TRUE(BitcastWVH != ConstantWVH);
  EXPECT_TRUE(BitcastV.get() != ConstantWVH);
  EXPECT_TRUE(BitcastWVH != ConstantV);
  EXPECT_FALSE(BitcastWVH != BitcastWVH);

  // Cast to Value* so comparisons work.
  Value *BV = BitcastV.get();
  Value *CV = ConstantV;
  EXPECT_EQ(BV < CV, BitcastWVH < ConstantWVH);
  EXPECT_EQ(BV <= CV, BitcastWVH <= ConstantWVH);
  EXPECT_EQ(BV > CV, BitcastWVH > ConstantWVH);
  EXPECT_EQ(BV >= CV, BitcastWVH >= ConstantWVH);

  EXPECT_EQ(BV < CV, BitcastV.get() < ConstantWVH);
  EXPECT_EQ(BV <= CV, BitcastV.get() <= ConstantWVH);
  EXPECT_EQ(BV > CV, BitcastV.get() > ConstantWVH);
  EXPECT_EQ(BV >= CV, BitcastV.get() >= ConstantWVH);

  EXPECT_EQ(BV < CV, BitcastWVH < ConstantV);
  EXPECT_EQ(BV <= CV, BitcastWVH <= ConstantV);
  EXPECT_EQ(BV > CV, BitcastWVH > ConstantV);
  EXPECT_EQ(BV >= CV, BitcastWVH >= ConstantV);
}

TEST_F(ValueHandle, WeakTrackingVH_FollowsRAUW) {
  WeakTrackingVH WVH(BitcastV.get());
  WeakTrackingVH WVH_Copy(WVH);
  WeakTrackingVH WVH_Recreated(BitcastV.get());
  BitcastV->replaceAllUsesWith(ConstantV);
  EXPECT_EQ(ConstantV, WVH);
  EXPECT_EQ(ConstantV, WVH_Copy);
  EXPECT_EQ(ConstantV, WVH_Recreated);
}

TEST_F(ValueHandle, WeakTrackingVH_NullOnDeletion) {
  WeakTrackingVH WVH(BitcastV.get());
  WeakTrackingVH WVH_Copy(WVH);
  WeakTrackingVH WVH_Recreated(BitcastV.get());
  BitcastV.reset();
  Value *null_value = nullptr;
  EXPECT_EQ(null_value, WVH);
  EXPECT_EQ(null_value, WVH_Copy);
  EXPECT_EQ(null_value, WVH_Recreated);
}


TEST_F(ValueHandle, AssertingVH_BasicOperation) {
  AssertingVH<CastInst> AVH(BitcastV.get());
  CastInst *implicit_to_exact_type = AVH;
  (void)implicit_to_exact_type;  // Avoid warning.

  AssertingVH<Value> GenericAVH(BitcastV.get());
  EXPECT_EQ(BitcastV.get(), GenericAVH);
  GenericAVH = ConstantV;
  EXPECT_EQ(ConstantV, GenericAVH);

  // Make sure I can call a method on the underlying CastInst.  It
  // doesn't matter which method.
  EXPECT_FALSE(AVH->mayWriteToMemory());
  EXPECT_FALSE((*AVH).mayWriteToMemory());
}

TEST_F(ValueHandle, AssertingVH_Const) {
  const CastInst *ConstBitcast = BitcastV.get();
  AssertingVH<const CastInst> AVH(ConstBitcast);
  const CastInst *implicit_to_exact_type = AVH;
  (void)implicit_to_exact_type;  // Avoid warning.
}

TEST_F(ValueHandle, AssertingVH_Comparisons) {
  AssertingVH<Value> BitcastAVH(BitcastV.get());
  AssertingVH<Value> ConstantAVH(ConstantV);

  EXPECT_TRUE(BitcastAVH == BitcastAVH);
  EXPECT_TRUE(BitcastV.get() == BitcastAVH);
  EXPECT_TRUE(BitcastAVH == BitcastV.get());
  EXPECT_FALSE(BitcastAVH == ConstantAVH);

  EXPECT_TRUE(BitcastAVH != ConstantAVH);
  EXPECT_TRUE(BitcastV.get() != ConstantAVH);
  EXPECT_TRUE(BitcastAVH != ConstantV);
  EXPECT_FALSE(BitcastAVH != BitcastAVH);

  // Cast to Value* so comparisons work.
  Value *BV = BitcastV.get();
  Value *CV = ConstantV;
  EXPECT_EQ(BV < CV, BitcastAVH < ConstantAVH);
  EXPECT_EQ(BV <= CV, BitcastAVH <= ConstantAVH);
  EXPECT_EQ(BV > CV, BitcastAVH > ConstantAVH);
  EXPECT_EQ(BV >= CV, BitcastAVH >= ConstantAVH);

  EXPECT_EQ(BV < CV, BitcastV.get() < ConstantAVH);
  EXPECT_EQ(BV <= CV, BitcastV.get() <= ConstantAVH);
  EXPECT_EQ(BV > CV, BitcastV.get() > ConstantAVH);
  EXPECT_EQ(BV >= CV, BitcastV.get() >= ConstantAVH);

  EXPECT_EQ(BV < CV, BitcastAVH < ConstantV);
  EXPECT_EQ(BV <= CV, BitcastAVH <= ConstantV);
  EXPECT_EQ(BV > CV, BitcastAVH > ConstantV);
  EXPECT_EQ(BV >= CV, BitcastAVH >= ConstantV);
}

TEST_F(ValueHandle, AssertingVH_DoesNotFollowRAUW) {
  AssertingVH<Value> AVH(BitcastV.get());
  BitcastV->replaceAllUsesWith(ConstantV);
  EXPECT_EQ(BitcastV.get(), AVH);
}

#ifdef NDEBUG

TEST_F(ValueHandle, AssertingVH_ReducesToPointer) {
  EXPECT_EQ(sizeof(CastInst *), sizeof(AssertingVH<CastInst>));
}

#elif LLVM_ENABLE_ABI_BREAKING_CHECKS // && !NDEBUG

#ifdef GTEST_HAS_DEATH_TEST

TEST_F(ValueHandle, AssertingVH_Asserts) {
  AssertingVH<Value> AVH(BitcastV.get());
  EXPECT_DEATH({BitcastV.reset();},
               "An asserting value handle still pointed to this value!");
  AssertingVH<Value> Copy(AVH);
  AVH = nullptr;
  EXPECT_DEATH({BitcastV.reset();},
               "An asserting value handle still pointed to this value!");
  Copy = nullptr;
  BitcastV.reset();
}

#endif  // GTEST_HAS_DEATH_TEST

#endif  // NDEBUG

TEST_F(ValueHandle, CallbackVH_BasicOperation) {
  ConcreteCallbackVH CVH(BitcastV.get());
  EXPECT_EQ(BitcastV.get(), CVH);
  CVH = ConstantV;
  EXPECT_EQ(ConstantV, CVH);

  // Make sure I can call a method on the underlying Value.  It
  // doesn't matter which method.
  EXPECT_EQ(Type::getInt32Ty(Context), CVH->getType());
  EXPECT_EQ(Type::getInt32Ty(Context), (*CVH).getType());
}

TEST_F(ValueHandle, CallbackVH_Comparisons) {
  ConcreteCallbackVH BitcastCVH(BitcastV.get());
  ConcreteCallbackVH ConstantCVH(ConstantV);

  EXPECT_TRUE(BitcastCVH == BitcastCVH);
  EXPECT_TRUE(BitcastV.get() == BitcastCVH);
  EXPECT_TRUE(BitcastCVH == BitcastV.get());
  EXPECT_FALSE(BitcastCVH == ConstantCVH);

  EXPECT_TRUE(BitcastCVH != ConstantCVH);
  EXPECT_TRUE(BitcastV.get() != ConstantCVH);
  EXPECT_TRUE(BitcastCVH != ConstantV);
  EXPECT_FALSE(BitcastCVH != BitcastCVH);

  // Cast to Value* so comparisons work.
  Value *BV = BitcastV.get();
  Value *CV = ConstantV;
  EXPECT_EQ(BV < CV, BitcastCVH < ConstantCVH);
  EXPECT_EQ(BV <= CV, BitcastCVH <= ConstantCVH);
  EXPECT_EQ(BV > CV, BitcastCVH > ConstantCVH);
  EXPECT_EQ(BV >= CV, BitcastCVH >= ConstantCVH);

  EXPECT_EQ(BV < CV, BitcastV.get() < ConstantCVH);
  EXPECT_EQ(BV <= CV, BitcastV.get() <= ConstantCVH);
  EXPECT_EQ(BV > CV, BitcastV.get() > ConstantCVH);
  EXPECT_EQ(BV >= CV, BitcastV.get() >= ConstantCVH);

  EXPECT_EQ(BV < CV, BitcastCVH < ConstantV);
  EXPECT_EQ(BV <= CV, BitcastCVH <= ConstantV);
  EXPECT_EQ(BV > CV, BitcastCVH > ConstantV);
  EXPECT_EQ(BV >= CV, BitcastCVH >= ConstantV);
}

TEST_F(ValueHandle, CallbackVH_CallbackOnDeletion) {
  class RecordingVH final : public CallbackVH {
  public:
    int DeletedCalls;
    int AURWCalls;

    RecordingVH() : DeletedCalls(0), AURWCalls(0) {}
    RecordingVH(Value *V) : CallbackVH(V), DeletedCalls(0), AURWCalls(0) {}

  private:
    void deleted() override {
      DeletedCalls++;
      CallbackVH::deleted();
    }
    void allUsesReplacedWith(Value *) override { AURWCalls++; }
  };

  RecordingVH RVH;
  RVH = BitcastV.get();
  EXPECT_EQ(0, RVH.DeletedCalls);
  EXPECT_EQ(0, RVH.AURWCalls);
  BitcastV.reset();
  EXPECT_EQ(1, RVH.DeletedCalls);
  EXPECT_EQ(0, RVH.AURWCalls);
}

TEST_F(ValueHandle, CallbackVH_CallbackOnRAUW) {
  class RecordingVH final : public CallbackVH {
  public:
    int DeletedCalls;
    Value *AURWArgument;

    RecordingVH() : DeletedCalls(0), AURWArgument(nullptr) {}
    RecordingVH(Value *V)
      : CallbackVH(V), DeletedCalls(0), AURWArgument(nullptr) {}

  private:
    void deleted() override {
      DeletedCalls++;
      CallbackVH::deleted();
    }
    void allUsesReplacedWith(Value *new_value) override {
      EXPECT_EQ(nullptr, AURWArgument);
      AURWArgument = new_value;
    }
  };

  RecordingVH RVH;
  RVH = BitcastV.get();
  EXPECT_EQ(0, RVH.DeletedCalls);
  EXPECT_EQ(nullptr, RVH.AURWArgument);
  BitcastV->replaceAllUsesWith(ConstantV);
  EXPECT_EQ(0, RVH.DeletedCalls);
  EXPECT_EQ(ConstantV, RVH.AURWArgument);
}

TEST_F(ValueHandle, CallbackVH_DeletionCanRAUW) {
  class RecoveringVH final : public CallbackVH {
  public:
    int DeletedCalls;
    Value *AURWArgument;
    LLVMContext *Context;

    RecoveringVH(LLVMContext &TheContext)
        : DeletedCalls(0), AURWArgument(nullptr), Context(&TheContext) {}

    RecoveringVH(LLVMContext &TheContext, Value *V)
        : CallbackVH(V), DeletedCalls(0), AURWArgument(nullptr),
          Context(&TheContext) {}

  private:
    void deleted() override {
      getValPtr()->replaceAllUsesWith(
          Constant::getNullValue(Type::getInt32Ty(*Context)));
      setValPtr(nullptr);
    }
    void allUsesReplacedWith(Value *new_value) override {
      ASSERT_TRUE(nullptr != getValPtr());
      EXPECT_TRUE(getValPtr()->hasOneUse());
      EXPECT_EQ(nullptr, AURWArgument);
      AURWArgument = new_value;
    }
  };

  // Normally, if a value has uses, deleting it will crash.  However, we can use
  // a CallbackVH to remove the uses before the check for no uses.
  RecoveringVH RVH(Context);
  RVH = RecoveringVH(Context, BitcastV.get());
  std::unique_ptr<BinaryOperator> BitcastUser(BinaryOperator::CreateAdd(
      RVH, Constant::getNullValue(Type::getInt32Ty(Context))));
  EXPECT_EQ(BitcastV.get(), BitcastUser->getOperand(0));
  BitcastV.reset();  // Would crash without the ValueHandler.
  EXPECT_EQ(Constant::getNullValue(Type::getInt32Ty(Context)),
            RVH.AURWArgument);
  EXPECT_EQ(Constant::getNullValue(Type::getInt32Ty(Context)),
            BitcastUser->getOperand(0));
}

TEST_F(ValueHandle, DestroyingOtherVHOnSameValueDoesntBreakIteration) {
  // When a CallbackVH modifies other ValueHandles in its callbacks,
  // that shouldn't interfere with non-modified ValueHandles receiving
  // their appropriate callbacks.
  //
  // We create the active CallbackVH in the middle of a palindromic
  // arrangement of other VHs so that the bad behavior would be
  // triggered in whichever order callbacks run.

  class DestroyingVH final : public CallbackVH {
  public:
    std::unique_ptr<WeakTrackingVH> ToClear[2];
    DestroyingVH(Value *V) {
      ToClear[0].reset(new WeakTrackingVH(V));
      setValPtr(V);
      ToClear[1].reset(new WeakTrackingVH(V));
    }
    void deleted() override {
      ToClear[0].reset();
      ToClear[1].reset();
      CallbackVH::deleted();
    }
    void allUsesReplacedWith(Value *) override {
      ToClear[0].reset();
      ToClear[1].reset();
    }
  };

  {
    WeakTrackingVH ShouldBeVisited1(BitcastV.get());
    DestroyingVH C(BitcastV.get());
    WeakTrackingVH ShouldBeVisited2(BitcastV.get());

    BitcastV->replaceAllUsesWith(ConstantV);
    EXPECT_EQ(ConstantV, static_cast<Value*>(ShouldBeVisited1));
    EXPECT_EQ(ConstantV, static_cast<Value*>(ShouldBeVisited2));
  }

  {
    WeakTrackingVH ShouldBeVisited1(BitcastV.get());
    DestroyingVH C(BitcastV.get());
    WeakTrackingVH ShouldBeVisited2(BitcastV.get());

    BitcastV.reset();
    EXPECT_EQ(nullptr, static_cast<Value*>(ShouldBeVisited1));
    EXPECT_EQ(nullptr, static_cast<Value*>(ShouldBeVisited2));
  }
}

TEST_F(ValueHandle, AssertingVHCheckedLast) {
  // If a CallbackVH exists to clear out a group of AssertingVHs on
  // Value deletion, the CallbackVH should get a chance to do so
  // before the AssertingVHs assert.

  class ClearingVH final : public CallbackVH {
  public:
    AssertingVH<Value> *ToClear[2];
    ClearingVH(Value *V,
               AssertingVH<Value> &A0, AssertingVH<Value> &A1)
      : CallbackVH(V) {
      ToClear[0] = &A0;
      ToClear[1] = &A1;
    }

    void deleted() override {
      *ToClear[0] = nullptr;
      *ToClear[1] = nullptr;
      CallbackVH::deleted();
    }
  };

  AssertingVH<Value> A1, A2;
  A1 = BitcastV.get();
  ClearingVH C(BitcastV.get(), A1, A2);
  A2 = BitcastV.get();
  // C.deleted() should run first, clearing the two AssertingVHs,
  // which should prevent them from asserting.
  BitcastV.reset();
}

TEST_F(ValueHandle, PoisoningVH_BasicOperation) {
  PoisoningVH<CastInst> VH(BitcastV.get());
  CastInst *implicit_to_exact_type = VH;
  (void)implicit_to_exact_type; // Avoid warning.

  PoisoningVH<Value> GenericVH(BitcastV.get());
  EXPECT_EQ(BitcastV.get(), GenericVH);
  GenericVH = ConstantV;
  EXPECT_EQ(ConstantV, GenericVH);

  // Make sure I can call a method on the underlying CastInst.  It
  // doesn't matter which method.
  EXPECT_FALSE(VH->mayWriteToMemory());
  EXPECT_FALSE((*VH).mayWriteToMemory());
}

TEST_F(ValueHandle, PoisoningVH_Const) {
  const CastInst *ConstBitcast = BitcastV.get();
  PoisoningVH<const CastInst> VH(ConstBitcast);
  const CastInst *implicit_to_exact_type = VH;
  (void)implicit_to_exact_type; // Avoid warning.
}

TEST_F(ValueHandle, PoisoningVH_Comparisons) {
  PoisoningVH<Value> BitcastVH(BitcastV.get());
  PoisoningVH<Value> ConstantVH(ConstantV);

  EXPECT_TRUE(BitcastVH == BitcastVH);
  EXPECT_TRUE(BitcastV.get() == BitcastVH);
  EXPECT_TRUE(BitcastVH == BitcastV.get());
  EXPECT_FALSE(BitcastVH == ConstantVH);

  EXPECT_TRUE(BitcastVH != ConstantVH);
  EXPECT_TRUE(BitcastV.get() != ConstantVH);
  EXPECT_TRUE(BitcastVH != ConstantV);
  EXPECT_FALSE(BitcastVH != BitcastVH);

  // Cast to Value* so comparisons work.
  Value *BV = BitcastV.get();
  Value *CV = ConstantV;
  EXPECT_EQ(BV < CV, BitcastVH < ConstantVH);
  EXPECT_EQ(BV <= CV, BitcastVH <= ConstantVH);
  EXPECT_EQ(BV > CV, BitcastVH > ConstantVH);
  EXPECT_EQ(BV >= CV, BitcastVH >= ConstantVH);

  EXPECT_EQ(BV < CV, BitcastV.get() < ConstantVH);
  EXPECT_EQ(BV <= CV, BitcastV.get() <= ConstantVH);
  EXPECT_EQ(BV > CV, BitcastV.get() > ConstantVH);
  EXPECT_EQ(BV >= CV, BitcastV.get() >= ConstantVH);

  EXPECT_EQ(BV < CV, BitcastVH < ConstantV);
  EXPECT_EQ(BV <= CV, BitcastVH <= ConstantV);
  EXPECT_EQ(BV > CV, BitcastVH > ConstantV);
  EXPECT_EQ(BV >= CV, BitcastVH >= ConstantV);
}

TEST_F(ValueHandle, PoisoningVH_DoesNotFollowRAUW) {
  PoisoningVH<Value> VH(BitcastV.get());
  BitcastV->replaceAllUsesWith(ConstantV);
  EXPECT_TRUE(DenseMapInfo<PoisoningVH<Value>>::isEqual(VH, BitcastV.get()));
}

TEST_F(ValueHandle, AssertingVH_MoveConstructor) {
  AssertingVH<Value> AVH(BitcastV.get());
  AssertingVH<Value> Moved(std::move(AVH));
  EXPECT_EQ(BitcastV.get(), Moved);
  // After move, AVH should be null.
  EXPECT_EQ(nullptr, (Value *)AVH);
}

TEST_F(ValueHandle, AssertingVH_MoveAssignment) {
  AssertingVH<Value> AVH(BitcastV.get());
  AssertingVH<Value> Other;
  Other = std::move(AVH);
  EXPECT_EQ(BitcastV.get(), Other);
  // After move, AVH should be null.
  EXPECT_EQ(nullptr, (Value *)AVH);
}

TEST_F(ValueHandle, AssertingVH_DenseMap) {
  DenseMap<AssertingVH<Value>, int> Map;
  Map.insert({BitcastV.get(), 1});
  Map.insert({ConstantV, 2});
  // These will create a temporary AssertingVH during lookup.
  EXPECT_TRUE(Map.contains(BitcastV.get()));
  EXPECT_TRUE(Map.contains(ConstantV));
  // These will not create a temporary AssertingVH.
  EXPECT_TRUE(Map.find_as(BitcastV.get()) != Map.end());
  EXPECT_TRUE(Map.find_as(ConstantV) != Map.end());
}

TEST_F(ValueHandle, PoisoningVH_DenseMap) {
  DenseMap<PoisoningVH<Value>, int> Map;
  Map.insert({BitcastV.get(), 1});
  Map.insert({ConstantV, 2});
  // These will create a temporary PoisoningVH during lookup.
  EXPECT_TRUE(Map.contains(BitcastV.get()));
  EXPECT_TRUE(Map.contains(ConstantV));
  // These will not create a temporary PoisoningVH.
  EXPECT_TRUE(Map.find_as(BitcastV.get()) != Map.end());
  EXPECT_TRUE(Map.find_as(ConstantV) != Map.end());
}

// A poisoned PoisoningVH is detached from its use list but keeps its raw
// pointer, so its use-list pointers are stale; relocating it must not relink
// through them. Reproduce the way ScalarEvolution does: a callback mutates a
// map embedding such handles while RAUW is still walking the use list. Here the
// callback grows the map, relocating the just-poisoned handles mid-walk.
TEST_F(ValueHandle, PoisoningVH_RelocatePoisoned) {
  using MapTy = DenseMap<int, SmallVector<PoisoningVH<Value>, 1>>;

  struct GrowCB final : CallbackVH {
    MapTy *Map;
    GrowCB(Value *V, MapTy *Map) : CallbackVH(V), Map(Map) {}
    void allUsesReplacedWith(Value *) override {
      for (unsigned I = 0; I != 256; ++I)
        (void)(*Map)[1000 + I];
    }
  };

  BasicBlock *BB = BasicBlock::Create(Context);
  BasicBlock *BB2 = BasicBlock::Create(Context);
  MapTy Map;
  // Registered first => processed last, after the handles below are poisoned.
  GrowCB CB(BB, &Map);
  for (unsigned I = 0; I != 8; ++I)
    Map[I].emplace_back(BB);
  BB->replaceAllUsesWith(BB2);
  EXPECT_EQ(Map.size(), 8u + 256u);

  BB->deleteValue();
  BB2->deleteValue();
}

#ifdef NDEBUG

TEST_F(ValueHandle, PoisoningVH_ReducesToPointer) {
  EXPECT_EQ(sizeof(CastInst *), sizeof(PoisoningVH<CastInst>));
}

#else // !NDEBUG

TEST_F(ValueHandle, TrackingVH_Tracks) {
  TrackingVH<Value> VH(BitcastV.get());
  BitcastV->replaceAllUsesWith(ConstantV);
  EXPECT_EQ(VH, ConstantV);
}

#ifdef GTEST_HAS_DEATH_TEST
#if LLVM_ENABLE_ABI_BREAKING_CHECKS

TEST_F(ValueHandle, PoisoningVH_Asserts) {
  PoisoningVH<Value> VH(BitcastV.get());

  // The poisoned handle shouldn't assert when the value is deleted.
  BitcastV.reset(new BitCastInst(ConstantV, Type::getInt32Ty(Context)));
  // But should when we access the handle.
  EXPECT_DEATH((void)*VH, "Accessed a poisoned value handle!");

  // Now check that poison catches RAUW.
  VH = BitcastV.get();
  // The replace doesn't trigger anything immediately.
  BitcastV->replaceAllUsesWith(ConstantV);
  // But a use does.
  EXPECT_DEATH((void)*VH, "Accessed a poisoned value handle!");

  // Don't clear anything out here as destroying the handles should be fine.
}

#endif // LLVM_ENABLE_ABI_BREAKING_CHECKS

TEST_F(ValueHandle, TrackingVH_Asserts) {
  {
    TrackingVH<Value> VH(BitcastV.get());

    // The tracking handle shouldn't assert when the value is deleted.
    BitcastV.reset(new BitCastInst(ConstantV, Type::getInt32Ty(Context)));
    // But should when we access the handle.
    EXPECT_DEATH((void)*VH,
                 "TrackingVH must be non-null and valid on dereference!");
  }

  {
    TrackingVH<Instruction> VH(BitcastV.get());

    BitcastV->replaceAllUsesWith(ConstantV);
    EXPECT_DEATH((void)*VH,
                 "Tracked Value was replaced by one with an invalid type!");
  }
}

#endif // GTEST_HAS_DEATH_TEST

#endif // NDEBUG
}