/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include/llvm/ADT/APInt.h

Bug Summary

File:	llvm/include/llvm/ADT/APInt.h
Warning:	line 403, column 36 The result of the right shift is undefined due to shifting by '64', which is greater or equal to the width of type 'llvm::APInt::WordType'

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name Local.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/Transforms/Utils -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/Transforms/Utils -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/Transforms/Utils -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include -D NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/Transforms/Utils -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-09-04-040900-46481-1 -x c++ /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/Transforms/Utils/Local.cpp

/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/Transforms/Utils/Local.cpp

→

1//===- Local.cpp - Functions to perform local transformations -------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This family of functions perform various local transformations to the
10// program.
11//
12//===----------------------------------------------------------------------===//

14#include "llvm/Transforms/Utils/Local.h"
15#include "llvm/ADT/APInt.h"
16#include "llvm/ADT/DenseMap.h"
17#include "llvm/ADT/DenseMapInfo.h"
18#include "llvm/ADT/DenseSet.h"
19#include "llvm/ADT/Hashing.h"
20#include "llvm/ADT/None.h"
21#include "llvm/ADT/Optional.h"
22#include "llvm/ADT/STLExtras.h"
23#include "llvm/ADT/SetVector.h"
24#include "llvm/ADT/SmallPtrSet.h"
25#include "llvm/ADT/SmallVector.h"
26#include "llvm/ADT/Statistic.h"
27#include "llvm/Analysis/AssumeBundleQueries.h"
28#include "llvm/Analysis/ConstantFolding.h"
29#include "llvm/Analysis/DomTreeUpdater.h"
30#include "llvm/Analysis/EHPersonalities.h"
31#include "llvm/Analysis/InstructionSimplify.h"
32#include "llvm/Analysis/LazyValueInfo.h"
33#include "llvm/Analysis/MemoryBuiltins.h"
34#include "llvm/Analysis/MemorySSAUpdater.h"
35#include "llvm/Analysis/TargetLibraryInfo.h"
36#include "llvm/Analysis/ValueTracking.h"
37#include "llvm/Analysis/VectorUtils.h"
38#include "llvm/BinaryFormat/Dwarf.h"
39#include "llvm/IR/Argument.h"
40#include "llvm/IR/Attributes.h"
41#include "llvm/IR/BasicBlock.h"
42#include "llvm/IR/CFG.h"
43#include "llvm/IR/Constant.h"
44#include "llvm/IR/ConstantRange.h"
45#include "llvm/IR/Constants.h"
46#include "llvm/IR/DIBuilder.h"
47#include "llvm/IR/DataLayout.h"
48#include "llvm/IR/DebugInfoMetadata.h"
49#include "llvm/IR/DebugLoc.h"
50#include "llvm/IR/DerivedTypes.h"
51#include "llvm/IR/Dominators.h"
52#include "llvm/IR/Function.h"
53#include "llvm/IR/GetElementPtrTypeIterator.h"
54#include "llvm/IR/GlobalObject.h"
55#include "llvm/IR/IRBuilder.h"
56#include "llvm/IR/InstrTypes.h"
57#include "llvm/IR/Instruction.h"
58#include "llvm/IR/Instructions.h"
59#include "llvm/IR/IntrinsicInst.h"
60#include "llvm/IR/Intrinsics.h"
61#include "llvm/IR/LLVMContext.h"
62#include "llvm/IR/MDBuilder.h"
63#include "llvm/IR/Metadata.h"
64#include "llvm/IR/Module.h"
65#include "llvm/IR/Operator.h"
66#include "llvm/IR/PatternMatch.h"
67#include "llvm/IR/PseudoProbe.h"
68#include "llvm/IR/Type.h"
69#include "llvm/IR/Use.h"
70#include "llvm/IR/User.h"
71#include "llvm/IR/Value.h"
72#include "llvm/IR/ValueHandle.h"
73#include "llvm/Support/Casting.h"
74#include "llvm/Support/Debug.h"
75#include "llvm/Support/ErrorHandling.h"
76#include "llvm/Support/KnownBits.h"
77#include "llvm/Support/raw_ostream.h"
78#include "llvm/Transforms/Utils/BasicBlockUtils.h"
79#include "llvm/Transforms/Utils/ValueMapper.h"
80#include <algorithm>
81#include <cassert>
82#include <climits>
83#include <cstdint>
84#include <iterator>
85#include <map>
86#include <utility>

88using namespace llvm;
89using namespace llvm::PatternMatch;

91#define DEBUG_TYPE"local" "local"

93STATISTIC(NumRemoved, "Number of unreachable basic blocks removed")static llvm::Statistic NumRemoved = {"local", "NumRemoved", "Number of unreachable basic blocks removed"
};
94STATISTIC(NumPHICSEs, "Number of PHI's that got CSE'd")static llvm::Statistic NumPHICSEs = {"local", "NumPHICSEs", "Number of PHI's that got CSE'd"
};

96static cl::opt<bool> PHICSEDebugHash(
  "phicse-debug-hash",
98#ifdef EXPENSIVE_CHECKS
  cl::init(true),
100#else
  cl::init(false),
102#endif
  cl::Hidden,
  cl::desc("Perform extra assertion checking to verify that PHINodes's hash "
           "function is well-behaved w.r.t. its isEqual predicate"));

107static cl::opt<unsigned> PHICSENumPHISmallSize(
  "phicse-num-phi-smallsize", cl::init(32), cl::Hidden,
  cl::desc(
      "When the basic block contains not more than this number of PHI nodes, "
      "perform a (faster!) exhaustive search instead of set-driven one."));

113// Max recursion depth for collectBitParts used when detecting bswap and
114// bitreverse idioms.
115static const unsigned BitPartRecursionMaxDepth = 48;

117//===----------------------------------------------------------------------===//
118//  Local constant propagation.
119//

121/// ConstantFoldTerminator - If a terminator instruction is predicated on a
122/// constant value, convert it into an unconditional branch to the constant
123/// destination.  This is a nontrivial operation because the successors of this
124/// basic block must have their PHI nodes updated.
125/// Also calls RecursivelyDeleteTriviallyDeadInstructions() on any branch/switch
126/// conditions and indirectbr addresses this might make dead if
127/// DeleteDeadConditions is true.
128bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
                                const TargetLibraryInfo *TLI,
                                DomTreeUpdater *DTU) {
Instruction *T = BB->getTerminator();
IRBuilder<> Builder(T);

// Branch - See if we are conditional jumping on constant
if (auto *BI = dyn_cast<BranchInst>(T)) {
  if (BI->isUnconditional()) return false;  // Can't optimize uncond branch

  BasicBlock *Dest1 = BI->getSuccessor(0);
  BasicBlock *Dest2 = BI->getSuccessor(1);

  if (Dest2 == Dest1) {       // Conditional branch to same location?
    // This branch matches something like this:
    //     br bool %cond, label %Dest, label %Dest
    // and changes it into:  br label %Dest

    // Let the basic block know that we are letting go of one copy of it.
    assert(BI->getParent() && "Terminator not inserted in block!")(static_cast<void> (0));
    Dest1->removePredecessor(BI->getParent());

    // Replace the conditional branch with an unconditional one.
    BranchInst *NewBI = Builder.CreateBr(Dest1);

    // Transfer the metadata to the new branch instruction.
    NewBI->copyMetadata(*BI, {LLVMContext::MD_loop, LLVMContext::MD_dbg,
                              LLVMContext::MD_annotation});

    Value *Cond = BI->getCondition();
    BI->eraseFromParent();
    if (DeleteDeadConditions)
      RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI);
    return true;
  }

  if (auto *Cond = dyn_cast<ConstantInt>(BI->getCondition())) {
    // Are we branching on constant?
    // YES.  Change to unconditional branch...
    BasicBlock *Destination = Cond->getZExtValue() ? Dest1 : Dest2;
    BasicBlock *OldDest = Cond->getZExtValue() ? Dest2 : Dest1;

    // Let the basic block know that we are letting go of it.  Based on this,
    // it will adjust it's PHI nodes.
    OldDest->removePredecessor(BB);

    // Replace the conditional branch with an unconditional one.
    BranchInst *NewBI = Builder.CreateBr(Destination);

    // Transfer the metadata to the new branch instruction.
    NewBI->copyMetadata(*BI, {LLVMContext::MD_loop, LLVMContext::MD_dbg,
                              LLVMContext::MD_annotation});

    BI->eraseFromParent();
    if (DTU)
      DTU->applyUpdates({{DominatorTree::Delete, BB, OldDest}});
    return true;
  }

  return false;
}

if (auto *SI = dyn_cast<SwitchInst>(T)) {
  // If we are switching on a constant, we can convert the switch to an
  // unconditional branch.
  auto *CI = dyn_cast<ConstantInt>(SI->getCondition());
  BasicBlock *DefaultDest = SI->getDefaultDest();
  BasicBlock *TheOnlyDest = DefaultDest;

  // If the default is unreachable, ignore it when searching for TheOnlyDest.
  if (isa<UnreachableInst>(DefaultDest->getFirstNonPHIOrDbg()) &&
      SI->getNumCases() > 0) {
    TheOnlyDest = SI->case_begin()->getCaseSuccessor();
  }

  bool Changed = false;

  // Figure out which case it goes to.
  for (auto i = SI->case_begin(), e = SI->case_end(); i != e;) {
    // Found case matching a constant operand?
    if (i->getCaseValue() == CI) {
      TheOnlyDest = i->getCaseSuccessor();
      break;
    }

    // Check to see if this branch is going to the same place as the default
    // dest.  If so, eliminate it as an explicit compare.
    if (i->getCaseSuccessor() == DefaultDest) {
      MDNode *MD = SI->getMetadata(LLVMContext::MD_prof);
      unsigned NCases = SI->getNumCases();
      // Fold the case metadata into the default if there will be any branches
      // left, unless the metadata doesn't match the switch.
      if (NCases > 1 && MD && MD->getNumOperands() == 2 + NCases) {
        // Collect branch weights into a vector.
        SmallVector<uint32_t, 8> Weights;
        for (unsigned MD_i = 1, MD_e = MD->getNumOperands(); MD_i < MD_e;
             ++MD_i) {
          auto *CI = mdconst::extract<ConstantInt>(MD->getOperand(MD_i));
          Weights.push_back(CI->getValue().getZExtValue());
        }
        // Merge weight of this case to the default weight.
        unsigned idx = i->getCaseIndex();
        Weights[0] += Weights[idx+1];
        // Remove weight for this case.
        std::swap(Weights[idx+1], Weights.back());
        Weights.pop_back();
        SI->setMetadata(LLVMContext::MD_prof,
                        MDBuilder(BB->getContext()).
                        createBranchWeights(Weights));
      }
      // Remove this entry.
      BasicBlock *ParentBB = SI->getParent();
      DefaultDest->removePredecessor(ParentBB);
      i = SI->removeCase(i);
      e = SI->case_end();
      Changed = true;
      continue;
    }

    // Otherwise, check to see if the switch only branches to one destination.
    // We do this by reseting "TheOnlyDest" to null when we find two non-equal
    // destinations.
    if (i->getCaseSuccessor() != TheOnlyDest)
      TheOnlyDest = nullptr;

    // Increment this iterator as we haven't removed the case.
    ++i;
  }

  if (CI && !TheOnlyDest) {
    // Branching on a constant, but not any of the cases, go to the default
    // successor.
    TheOnlyDest = SI->getDefaultDest();
  }

  // If we found a single destination that we can fold the switch into, do so
  // now.
  if (TheOnlyDest) {
    // Insert the new branch.
    Builder.CreateBr(TheOnlyDest);
    BasicBlock *BB = SI->getParent();

    SmallSet<BasicBlock *, 8> RemovedSuccessors;

    // Remove entries from PHI nodes which we no longer branch to...
    BasicBlock *SuccToKeep = TheOnlyDest;
    for (BasicBlock *Succ : successors(SI)) {
      if (DTU && Succ != TheOnlyDest)
        RemovedSuccessors.insert(Succ);
      // Found case matching a constant operand?
      if (Succ == SuccToKeep) {
        SuccToKeep = nullptr; // Don't modify the first branch to TheOnlyDest
      } else {
        Succ->removePredecessor(BB);
      }
    }

    // Delete the old switch.
    Value *Cond = SI->getCondition();
    SI->eraseFromParent();
    if (DeleteDeadConditions)
      RecursivelyDeleteTriviallyDeadInstructions(Cond, TLI);
    if (DTU) {
      std::vector<DominatorTree::UpdateType> Updates;
      Updates.reserve(RemovedSuccessors.size());
      for (auto *RemovedSuccessor : RemovedSuccessors)
        Updates.push_back({DominatorTree::Delete, BB, RemovedSuccessor});
      DTU->applyUpdates(Updates);
    }
    return true;
  }

  if (SI->getNumCases() == 1) {
    // Otherwise, we can fold this switch into a conditional branch
    // instruction if it has only one non-default destination.
    auto FirstCase = *SI->case_begin();
    Value *Cond = Builder.CreateICmpEQ(SI->getCondition(),
        FirstCase.getCaseValue(), "cond");

    // Insert the new branch.
    BranchInst *NewBr = Builder.CreateCondBr(Cond,
                                             FirstCase.getCaseSuccessor(),
                                             SI->getDefaultDest());
    MDNode *MD = SI->getMetadata(LLVMContext::MD_prof);
    if (MD && MD->getNumOperands() == 3) {
      ConstantInt *SICase =
          mdconst::dyn_extract<ConstantInt>(MD->getOperand(2));
      ConstantInt *SIDef =
          mdconst::dyn_extract<ConstantInt>(MD->getOperand(1));
      assert(SICase && SIDef)(static_cast<void> (0));
      // The TrueWeight should be the weight for the single case of SI.
      NewBr->setMetadata(LLVMContext::MD_prof,
                      MDBuilder(BB->getContext()).
                      createBranchWeights(SICase->getValue().getZExtValue(),
                                          SIDef->getValue().getZExtValue()));
    }

    // Update make.implicit metadata to the newly-created conditional branch.
    MDNode *MakeImplicitMD = SI->getMetadata(LLVMContext::MD_make_implicit);
    if (MakeImplicitMD)
      NewBr->setMetadata(LLVMContext::MD_make_implicit, MakeImplicitMD);

    // Delete the old switch.
    SI->eraseFromParent();
    return true;
  }
  return Changed;
}

if (auto *IBI = dyn_cast<IndirectBrInst>(T)) {
  // indirectbr blockaddress(@F, @BB) -> br label @BB
  if (auto *BA =
        dyn_cast<BlockAddress>(IBI->getAddress()->stripPointerCasts())) {
    BasicBlock *TheOnlyDest = BA->getBasicBlock();
    SmallSet<BasicBlock *, 8> RemovedSuccessors;

    // Insert the new branch.
    Builder.CreateBr(TheOnlyDest);

    BasicBlock *SuccToKeep = TheOnlyDest;
    for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) {
      BasicBlock *DestBB = IBI->getDestination(i);
      if (DTU && DestBB != TheOnlyDest)
        RemovedSuccessors.insert(DestBB);
      if (IBI->getDestination(i) == SuccToKeep) {
        SuccToKeep = nullptr;
      } else {
        DestBB->removePredecessor(BB);
      }
    }
    Value *Address = IBI->getAddress();
    IBI->eraseFromParent();
    if (DeleteDeadConditions)
      // Delete pointer cast instructions.
      RecursivelyDeleteTriviallyDeadInstructions(Address, TLI);

    // Also zap the blockaddress constant if there are no users remaining,
    // otherwise the destination is still marked as having its address taken.
    if (BA->use_empty())
      BA->destroyConstant();

    // If we didn't find our destination in the IBI successor list, then we
    // have undefined behavior.  Replace the unconditional branch with an
    // 'unreachable' instruction.
    if (SuccToKeep) {
      BB->getTerminator()->eraseFromParent();
      new UnreachableInst(BB->getContext(), BB);
    }

    if (DTU) {
      std::vector<DominatorTree::UpdateType> Updates;
      Updates.reserve(RemovedSuccessors.size());
      for (auto *RemovedSuccessor : RemovedSuccessors)
        Updates.push_back({DominatorTree::Delete, BB, RemovedSuccessor});
      DTU->applyUpdates(Updates);
    }
    return true;
  }
}

return false;
389}

391//===----------------------------------------------------------------------===//
392//  Local dead code elimination.
393//

395/// isInstructionTriviallyDead - Return true if the result produced by the
396/// instruction is not used, and the instruction has no side effects.
397///
398bool llvm::isInstructionTriviallyDead(Instruction *I,
                                    const TargetLibraryInfo *TLI) {
if (!I->use_empty())
  return false;
return wouldInstructionBeTriviallyDead(I, TLI);
403}

405bool llvm::wouldInstructionBeTriviallyDead(Instruction *I,
                                         const TargetLibraryInfo *TLI) {
if (I->isTerminator())
  return false;

// We don't want the landingpad-like instructions removed by anything this
// general.
if (I->isEHPad())
  return false;

// We don't want debug info removed by anything this general, unless
// debug info is empty.
if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(I)) {
  if (DDI->getAddress())
    return false;
  return true;
}
if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(I)) {
  if (DVI->hasArgList() || DVI->getValue(0))
    return false;
  return true;
}
if (DbgLabelInst *DLI = dyn_cast<DbgLabelInst>(I)) {
  if (DLI->getLabel())
    return false;
  return true;
}

if (!I->willReturn())
  return false;

if (!I->mayHaveSideEffects())
  return true;

// Special case intrinsics that "may have side effects" but can be deleted
// when dead.
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
  // Safe to delete llvm.stacksave and launder.invariant.group if dead.
  if (II->getIntrinsicID() == Intrinsic::stacksave ||
      II->getIntrinsicID() == Intrinsic::launder_invariant_group)
    return true;

  if (II->isLifetimeStartOrEnd()) {
    auto *Arg = II->getArgOperand(1);
    // Lifetime intrinsics are dead when their right-hand is undef.
    if (isa<UndefValue>(Arg))
      return true;
    // If the right-hand is an alloc, global, or argument and the only uses
    // are lifetime intrinsics then the intrinsics are dead.
    if (isa<AllocaInst>(Arg) || isa<GlobalValue>(Arg) || isa<Argument>(Arg))
      return llvm::all_of(Arg->uses(), [](Use &Use) {
        if (IntrinsicInst *IntrinsicUse =
                dyn_cast<IntrinsicInst>(Use.getUser()))
          return IntrinsicUse->isLifetimeStartOrEnd();
        return false;
      });
    return false;
  }

  // Assumptions are dead if their condition is trivially true.  Guards on
  // true are operationally no-ops.  In the future we can consider more
  // sophisticated tradeoffs for guards considering potential for check
  // widening, but for now we keep things simple.
  if ((II->getIntrinsicID() == Intrinsic::assume &&
       isAssumeWithEmptyBundle(cast<AssumeInst>(*II))) ||
      II->getIntrinsicID() == Intrinsic::experimental_guard) {
    if (ConstantInt *Cond = dyn_cast<ConstantInt>(II->getArgOperand(0)))
      return !Cond->isZero();

    return false;
  }

  if (auto *FPI = dyn_cast<ConstrainedFPIntrinsic>(I)) {
    Optional<fp::ExceptionBehavior> ExBehavior = FPI->getExceptionBehavior();
    return ExBehavior.getValue() != fp::ebStrict;
  }
}

if (isAllocLikeFn(I, TLI))
  return true;

if (CallInst *CI = isFreeCall(I, TLI))
  if (Constant *C = dyn_cast<Constant>(CI->getArgOperand(0)))
    return C->isNullValue() || isa<UndefValue>(C);

if (auto *Call = dyn_cast<CallBase>(I))
  if (isMathLibCallNoop(Call, TLI))
    return true;

// To express possible interaction with floating point environment constrained
// intrinsics are described as if they access memory. So they look like having
// side effect but actually do not have it unless they raise floating point
// exception. If FP exceptions are ignored, the intrinsic may be deleted.
if (auto *CI = dyn_cast<ConstrainedFPIntrinsic>(I)) {
  Optional<fp::ExceptionBehavior> EB = CI->getExceptionBehavior();
  if (!EB || *EB == fp::ExceptionBehavior::ebIgnore)
    return true;
}

return false;
505}

507/// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
508/// trivially dead instruction, delete it.  If that makes any of its operands
509/// trivially dead, delete them too, recursively.  Return true if any
510/// instructions were deleted.
511bool llvm::RecursivelyDeleteTriviallyDeadInstructions(
  Value *V, const TargetLibraryInfo *TLI, MemorySSAUpdater *MSSAU,
  std::function<void(Value *)> AboutToDeleteCallback) {
Instruction *I = dyn_cast<Instruction>(V);
if (!I || !isInstructionTriviallyDead(I, TLI))
  return false;

SmallVector<WeakTrackingVH, 16> DeadInsts;
DeadInsts.push_back(I);
RecursivelyDeleteTriviallyDeadInstructions(DeadInsts, TLI, MSSAU,
                                           AboutToDeleteCallback);

return true;
524}

526bool llvm::RecursivelyDeleteTriviallyDeadInstructionsPermissive(
  SmallVectorImpl<WeakTrackingVH> &DeadInsts, const TargetLibraryInfo *TLI,
  MemorySSAUpdater *MSSAU,
  std::function<void(Value *)> AboutToDeleteCallback) {
unsigned S = 0, E = DeadInsts.size(), Alive = 0;
for (; S != E; ++S) {
  auto *I = cast<Instruction>(DeadInsts[S]);
  if (!isInstructionTriviallyDead(I)) {
    DeadInsts[S] = nullptr;
    ++Alive;
  }
}
if (Alive == E)
  return false;
RecursivelyDeleteTriviallyDeadInstructions(DeadInsts, TLI, MSSAU,
                                           AboutToDeleteCallback);
return true;
543}

545void llvm::RecursivelyDeleteTriviallyDeadInstructions(
  SmallVectorImpl<WeakTrackingVH> &DeadInsts, const TargetLibraryInfo *TLI,
  MemorySSAUpdater *MSSAU,
  std::function<void(Value *)> AboutToDeleteCallback) {
// Process the dead instruction list until empty.
while (!DeadInsts.empty()) {
  Value *V = DeadInsts.pop_back_val();
  Instruction *I = cast_or_null<Instruction>(V);
  if (!I)
    continue;
  assert(isInstructionTriviallyDead(I, TLI) &&(static_cast<void> (0))
         "Live instruction found in dead worklist!")(static_cast<void> (0));
  assert(I->use_empty() && "Instructions with uses are not dead.")(static_cast<void> (0));

  // Don't lose the debug info while deleting the instructions.
  salvageDebugInfo(*I);

  if (AboutToDeleteCallback)
    AboutToDeleteCallback(I);

  // Null out all of the instruction's operands to see if any operand becomes
  // dead as we go.
  for (Use &OpU : I->operands()) {
    Value *OpV = OpU.get();
    OpU.set(nullptr);

    if (!OpV->use_empty())
      continue;

    // If the operand is an instruction that became dead as we nulled out the
    // operand, and if it is 'trivially' dead, delete it in a future loop
    // iteration.
    if (Instruction *OpI = dyn_cast<Instruction>(OpV))
      if (isInstructionTriviallyDead(OpI, TLI))
        DeadInsts.push_back(OpI);
  }
  if (MSSAU)
    MSSAU->removeMemoryAccess(I);

  I->eraseFromParent();
}
586}

588bool llvm::replaceDbgUsesWithUndef(Instruction *I) {
SmallVector<DbgVariableIntrinsic *, 1> DbgUsers;
findDbgUsers(DbgUsers, I);
for (auto *DII : DbgUsers) {
  Value *Undef = UndefValue::get(I->getType());
  DII->replaceVariableLocationOp(I, Undef);
}
return !DbgUsers.empty();
596}

598/// areAllUsesEqual - Check whether the uses of a value are all the same.
599/// This is similar to Instruction::hasOneUse() except this will also return
600/// true when there are no uses or multiple uses that all refer to the same
601/// value.
602static bool areAllUsesEqual(Instruction *I) {
Value::user_iterator UI = I->user_begin();
Value::user_iterator UE = I->user_end();
if (UI == UE)
  return true;

User *TheUse = *UI;
for (++UI; UI != UE; ++UI) {
  if (*UI != TheUse)
    return false;
}
return true;
614}

616/// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
617/// dead PHI node, due to being a def-use chain of single-use nodes that
618/// either forms a cycle or is terminated by a trivially dead instruction,
619/// delete it.  If that makes any of its operands trivially dead, delete them
620/// too, recursively.  Return true if a change was made.
621bool llvm::RecursivelyDeleteDeadPHINode(PHINode *PN,
                                      const TargetLibraryInfo *TLI,
                                      llvm::MemorySSAUpdater *MSSAU) {
SmallPtrSet<Instruction*, 4> Visited;
for (Instruction *I = PN; areAllUsesEqual(I) && !I->mayHaveSideEffects();
     I = cast<Instruction>(*I->user_begin())) {
  if (I->use_empty())
    return RecursivelyDeleteTriviallyDeadInstructions(I, TLI, MSSAU);

  // If we find an instruction more than once, we're on a cycle that
  // won't prove fruitful.
  if (!Visited.insert(I).second) {
    // Break the cycle and delete the instruction and its operands.
    I->replaceAllUsesWith(UndefValue::get(I->getType()));
    (void)RecursivelyDeleteTriviallyDeadInstructions(I, TLI, MSSAU);
    return true;
  }
}
return false;
640}

642static bool
643simplifyAndDCEInstruction(Instruction *I,
                        SmallSetVector<Instruction *, 16> &WorkList,
                        const DataLayout &DL,
                        const TargetLibraryInfo *TLI) {
if (isInstructionTriviallyDead(I, TLI)) {
  salvageDebugInfo(*I);

  // Null out all of the instruction's operands to see if any operand becomes
  // dead as we go.
  for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
    Value *OpV = I->getOperand(i);
    I->setOperand(i, nullptr);

    if (!OpV->use_empty() || I == OpV)
      continue;

    // If the operand is an instruction that became dead as we nulled out the
    // operand, and if it is 'trivially' dead, delete it in a future loop
    // iteration.
    if (Instruction *OpI = dyn_cast<Instruction>(OpV))
      if (isInstructionTriviallyDead(OpI, TLI))
        WorkList.insert(OpI);
  }

  I->eraseFromParent();

  return true;
}

if (Value *SimpleV = SimplifyInstruction(I, DL)) {
  // Add the users to the worklist. CAREFUL: an instruction can use itself,
  // in the case of a phi node.
  for (User *U : I->users()) {
    if (U != I) {
      WorkList.insert(cast<Instruction>(U));
    }
  }

  // Replace the instruction with its simplified value.
  bool Changed = false;
  if (!I->use_empty()) {
    I->replaceAllUsesWith(SimpleV);
    Changed = true;
  }
  if (isInstructionTriviallyDead(I, TLI)) {
    I->eraseFromParent();
    Changed = true;
  }
  return Changed;
}
return false;
694}

696/// SimplifyInstructionsInBlock - Scan the specified basic block and try to
697/// simplify any instructions in it and recursively delete dead instructions.
698///
699/// This returns true if it changed the code, note that it can delete
700/// instructions in other blocks as well in this block.
701bool llvm::SimplifyInstructionsInBlock(BasicBlock *BB,
                                     const TargetLibraryInfo *TLI) {
bool MadeChange = false;
const DataLayout &DL = BB->getModule()->getDataLayout();

706#ifndef NDEBUG1
// In debug builds, ensure that the terminator of the block is never replaced
// or deleted by these simplifications. The idea of simplification is that it
// cannot introduce new instructions, and there is no way to replace the
// terminator of a block without introducing a new instruction.
AssertingVH<Instruction> TerminatorVH(&BB->back());
712#endif

SmallSetVector<Instruction *, 16> WorkList;
// Iterate over the original function, only adding insts to the worklist
// if they actually need to be revisited. This avoids having to pre-init
// the worklist with the entire function's worth of instructions.
for (BasicBlock::iterator BI = BB->begin(), E = std::prev(BB->end());
     BI != E;) {
  assert(!BI->isTerminator())(static_cast<void> (0));
  Instruction *I = &*BI;
  ++BI;

  // We're visiting this instruction now, so make sure it's not in the
  // worklist from an earlier visit.
  if (!WorkList.count(I))
    MadeChange |= simplifyAndDCEInstruction(I, WorkList, DL, TLI);
}

while (!WorkList.empty()) {
  Instruction *I = WorkList.pop_back_val();
  MadeChange |= simplifyAndDCEInstruction(I, WorkList, DL, TLI);
}
return MadeChange;
735}

737//===----------------------------------------------------------------------===//
738//  Control Flow Graph Restructuring.
739//

741void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB,
                                     DomTreeUpdater *DTU) {

// If BB has single-entry PHI nodes, fold them.
while (PHINode *PN = dyn_cast<PHINode>(DestBB->begin())) {
  Value *NewVal = PN->getIncomingValue(0);
  // Replace self referencing PHI with undef, it must be dead.
  if (NewVal == PN) NewVal = UndefValue::get(PN->getType());
  PN->replaceAllUsesWith(NewVal);
  PN->eraseFromParent();
}

BasicBlock *PredBB = DestBB->getSinglePredecessor();
assert(PredBB && "Block doesn't have a single predecessor!")(static_cast<void> (0));

bool ReplaceEntryBB = PredBB->isEntryBlock();

// DTU updates: Collect all the edges that enter
// PredBB. These dominator edges will be redirected to DestBB.
SmallVector<DominatorTree::UpdateType, 32> Updates;

if (DTU) {
  SmallPtrSet<BasicBlock *, 2> PredsOfPredBB(pred_begin(PredBB),
                                             pred_end(PredBB));
  Updates.reserve(Updates.size() + 2 * PredsOfPredBB.size() + 1);
  for (BasicBlock *PredOfPredBB : PredsOfPredBB)
    // This predecessor of PredBB may already have DestBB as a successor.
    if (PredOfPredBB != PredBB)
      Updates.push_back({DominatorTree::Insert, PredOfPredBB, DestBB});
  for (BasicBlock *PredOfPredBB : PredsOfPredBB)
    Updates.push_back({DominatorTree::Delete, PredOfPredBB, PredBB});
  Updates.push_back({DominatorTree::Delete, PredBB, DestBB});
}

// Zap anything that took the address of DestBB.  Not doing this will give the
// address an invalid value.
if (DestBB->hasAddressTaken()) {
  BlockAddress *BA = BlockAddress::get(DestBB);
  Constant *Replacement =
    ConstantInt::get(Type::getInt32Ty(BA->getContext()), 1);
  BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(Replacement,
                                                   BA->getType()));
  BA->destroyConstant();
}

// Anything that branched to PredBB now branches to DestBB.
PredBB->replaceAllUsesWith(DestBB);

// Splice all the instructions from PredBB to DestBB.
PredBB->getTerminator()->eraseFromParent();
DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList());
new UnreachableInst(PredBB->getContext(), PredBB);

// If the PredBB is the entry block of the function, move DestBB up to
// become the entry block after we erase PredBB.
if (ReplaceEntryBB)
  DestBB->moveAfter(PredBB);

if (DTU) {
  assert(PredBB->getInstList().size() == 1 &&(static_cast<void> (0))
         isa<UnreachableInst>(PredBB->getTerminator()) &&(static_cast<void> (0))
         "The successor list of PredBB isn't empty before "(static_cast<void> (0))
         "applying corresponding DTU updates.")(static_cast<void> (0));
  DTU->applyUpdatesPermissive(Updates);
  DTU->deleteBB(PredBB);
  // Recalculation of DomTree is needed when updating a forward DomTree and
  // the Entry BB is replaced.
  if (ReplaceEntryBB && DTU->hasDomTree()) {
    // The entry block was removed and there is no external interface for
    // the dominator tree to be notified of this change. In this corner-case
    // we recalculate the entire tree.
    DTU->recalculate(*(DestBB->getParent()));
  }
}

else {
  PredBB->eraseFromParent(); // Nuke BB if DTU is nullptr.
}
819}

821/// Return true if we can choose one of these values to use in place of the
822/// other. Note that we will always choose the non-undef value to keep.
823static bool CanMergeValues(Value *First, Value *Second) {
return First == Second || isa<UndefValue>(First) || isa<UndefValue>(Second);
825}

827/// Return true if we can fold BB, an almost-empty BB ending in an unconditional
828/// branch to Succ, into Succ.
829///
830/// Assumption: Succ is the single successor for BB.
831static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
assert(*succ_begin(BB) == Succ && "Succ is not successor of BB!")(static_cast<void> (0));

LLVM_DEBUG(dbgs() << "Looking to fold " << BB->getName() << " into "do { } while (false)
                  << Succ->getName() << "\n")do { } while (false);
// Shortcut, if there is only a single predecessor it must be BB and merging
// is always safe
if (Succ->getSinglePredecessor()) return true;

// Make a list of the predecessors of BB
SmallPtrSet<BasicBlock*, 16> BBPreds(pred_begin(BB), pred_end(BB));

// Look at all the phi nodes in Succ, to see if they present a conflict when
// merging these blocks
for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
  PHINode *PN = cast<PHINode>(I);

  // If the incoming value from BB is again a PHINode in
  // BB which has the same incoming value for *PI as PN does, we can
  // merge the phi nodes and then the blocks can still be merged
  PHINode *BBPN = dyn_cast<PHINode>(PN->getIncomingValueForBlock(BB));
  if (BBPN && BBPN->getParent() == BB) {
    for (unsigned PI = 0, PE = PN->getNumIncomingValues(); PI != PE; ++PI) {
      BasicBlock *IBB = PN->getIncomingBlock(PI);
      if (BBPreds.count(IBB) &&
          !CanMergeValues(BBPN->getIncomingValueForBlock(IBB),
                          PN->getIncomingValue(PI))) {
        LLVM_DEBUG(dbgs()do { } while (false)
                   << "Can't fold, phi node " << PN->getName() << " in "do { } while (false)
                   << Succ->getName() << " is conflicting with "do { } while (false)
                   << BBPN->getName() << " with regard to common predecessor "do { } while (false)
                   << IBB->getName() << "\n")do { } while (false);
        return false;
      }
    }
  } else {
    Value* Val = PN->getIncomingValueForBlock(BB);
    for (unsigned PI = 0, PE = PN->getNumIncomingValues(); PI != PE; ++PI) {
      // See if the incoming value for the common predecessor is equal to the
      // one for BB, in which case this phi node will not prevent the merging
      // of the block.
      BasicBlock *IBB = PN->getIncomingBlock(PI);
      if (BBPreds.count(IBB) &&
          !CanMergeValues(Val, PN->getIncomingValue(PI))) {
        LLVM_DEBUG(dbgs() << "Can't fold, phi node " << PN->getName()do { } while (false)
                          << " in " << Succ->getName()do { } while (false)
                          << " is conflicting with regard to common "do { } while (false)
                          << "predecessor " << IBB->getName() << "\n")do { } while (false);
        return false;
      }
    }
  }
}

return true;
886}

888using PredBlockVector = SmallVector<BasicBlock *, 16>;
889using IncomingValueMap = DenseMap<BasicBlock *, Value *>;

891/// Determines the value to use as the phi node input for a block.
892///
893/// Select between \p OldVal any value that we know flows from \p BB
894/// to a particular phi on the basis of which one (if either) is not
895/// undef. Update IncomingValues based on the selected value.
896///
897/// \param OldVal The value we are considering selecting.
898/// \param BB The block that the value flows in from.
899/// \param IncomingValues A map from block-to-value for other phi inputs
900/// that we have examined.
901///
902/// \returns the selected value.
903static Value *selectIncomingValueForBlock(Value *OldVal, BasicBlock *BB,
                                        IncomingValueMap &IncomingValues) {
if (!isa<UndefValue>(OldVal)) {
  assert((!IncomingValues.count(BB) ||(static_cast<void> (0))
          IncomingValues.find(BB)->second == OldVal) &&(static_cast<void> (0))
         "Expected OldVal to match incoming value from BB!")(static_cast<void> (0));

  IncomingValues.insert(std::make_pair(BB, OldVal));
  return OldVal;
}

IncomingValueMap::const_iterator It = IncomingValues.find(BB);
if (It != IncomingValues.end()) return It->second;

return OldVal;
918}

920/// Create a map from block to value for the operands of a
921/// given phi.
922///
923/// Create a map from block to value for each non-undef value flowing
924/// into \p PN.
925///
926/// \param PN The phi we are collecting the map for.
927/// \param IncomingValues [out] The map from block to value for this phi.
928static void gatherIncomingValuesToPhi(PHINode *PN,
                                    IncomingValueMap &IncomingValues) {
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
  BasicBlock *BB = PN->getIncomingBlock(i);
  Value *V = PN->getIncomingValue(i);

  if (!isa<UndefValue>(V))
    IncomingValues.insert(std::make_pair(BB, V));
}
937}

939/// Replace the incoming undef values to a phi with the values
940/// from a block-to-value map.
941///
942/// \param PN The phi we are replacing the undefs in.
943/// \param IncomingValues A map from block to value.
944static void replaceUndefValuesInPhi(PHINode *PN,
                                  const IncomingValueMap &IncomingValues) {
SmallVector<unsigned> TrueUndefOps;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
  Value *V = PN->getIncomingValue(i);

  if (!isa<UndefValue>(V)) continue;

  BasicBlock *BB = PN->getIncomingBlock(i);
  IncomingValueMap::const_iterator It = IncomingValues.find(BB);

  // Keep track of undef/poison incoming values. Those must match, so we fix
  // them up below if needed.
  // Note: this is conservatively correct, but we could try harder and group
  // the undef values per incoming basic block.
  if (It == IncomingValues.end()) {
    TrueUndefOps.push_back(i);
    continue;
  }

  // There is a defined value for this incoming block, so map this undef
  // incoming value to the defined value.
  PN->setIncomingValue(i, It->second);
}

// If there are both undef and poison values incoming, then convert those
// values to undef. It is invalid to have different values for the same
// incoming block.
unsigned PoisonCount = count_if(TrueUndefOps, [&](unsigned i) {
  return isa<PoisonValue>(PN->getIncomingValue(i));
});
if (PoisonCount != 0 && PoisonCount != TrueUndefOps.size()) {
  for (unsigned i : TrueUndefOps)
    PN->setIncomingValue(i, UndefValue::get(PN->getType()));
}
979}

981/// Replace a value flowing from a block to a phi with
982/// potentially multiple instances of that value flowing from the
983/// block's predecessors to the phi.
984///
985/// \param BB The block with the value flowing into the phi.
986/// \param BBPreds The predecessors of BB.
987/// \param PN The phi that we are updating.
988static void redirectValuesFromPredecessorsToPhi(BasicBlock *BB,
                                              const PredBlockVector &BBPreds,
                                              PHINode *PN) {
Value *OldVal = PN->removeIncomingValue(BB, false);
assert(OldVal && "No entry in PHI for Pred BB!")(static_cast<void> (0));

IncomingValueMap IncomingValues;

// We are merging two blocks - BB, and the block containing PN - and
// as a result we need to redirect edges from the predecessors of BB
// to go to the block containing PN, and update PN
// accordingly. Since we allow merging blocks in the case where the
// predecessor and successor blocks both share some predecessors,
// and where some of those common predecessors might have undef
// values flowing into PN, we want to rewrite those values to be
// consistent with the non-undef values.

gatherIncomingValuesToPhi(PN, IncomingValues);

// If this incoming value is one of the PHI nodes in BB, the new entries
// in the PHI node are the entries from the old PHI.
if (isa<PHINode>(OldVal) && cast<PHINode>(OldVal)->getParent() == BB) {
  PHINode *OldValPN = cast<PHINode>(OldVal);
  for (unsigned i = 0, e = OldValPN->getNumIncomingValues(); i != e; ++i) {
    // Note that, since we are merging phi nodes and BB and Succ might
    // have common predecessors, we could end up with a phi node with
    // identical incoming branches. This will be cleaned up later (and
    // will trigger asserts if we try to clean it up now, without also
    // simplifying the corresponding conditional branch).
    BasicBlock *PredBB = OldValPN->getIncomingBlock(i);
    Value *PredVal = OldValPN->getIncomingValue(i);
    Value *Selected = selectIncomingValueForBlock(PredVal, PredBB,
                                                  IncomingValues);

    // And add a new incoming value for this predecessor for the
    // newly retargeted branch.
    PN->addIncoming(Selected, PredBB);
  }
} else {
  for (unsigned i = 0, e = BBPreds.size(); i != e; ++i) {
    // Update existing incoming values in PN for this
    // predecessor of BB.
    BasicBlock *PredBB = BBPreds[i];
    Value *Selected = selectIncomingValueForBlock(OldVal, PredBB,
                                                  IncomingValues);

    // And add a new incoming value for this predecessor for the
    // newly retargeted branch.
    PN->addIncoming(Selected, PredBB);
  }
}

replaceUndefValuesInPhi(PN, IncomingValues);
1041}

1043bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
                                                 DomTreeUpdater *DTU) {
assert(BB != &BB->getParent()->getEntryBlock() &&(static_cast<void> (0))
       "TryToSimplifyUncondBranchFromEmptyBlock called on entry block!")(static_cast<void> (0));

// We can't eliminate infinite loops.
BasicBlock *Succ = cast<BranchInst>(BB->getTerminator())->getSuccessor(0);
if (BB == Succ) return false;

// Check to see if merging these blocks would cause conflicts for any of the
// phi nodes in BB or Succ. If not, we can safely merge.
if (!CanPropagatePredecessorsForPHIs(BB, Succ)) return false;

// Check for cases where Succ has multiple predecessors and a PHI node in BB
// has uses which will not disappear when the PHI nodes are merged.  It is
// possible to handle such cases, but difficult: it requires checking whether
// BB dominates Succ, which is non-trivial to calculate in the case where
// Succ has multiple predecessors.  Also, it requires checking whether
// constructing the necessary self-referential PHI node doesn't introduce any
// conflicts; this isn't too difficult, but the previous code for doing this
// was incorrect.
//
// Note that if this check finds a live use, BB dominates Succ, so BB is
// something like a loop pre-header (or rarely, a part of an irreducible CFG);
// folding the branch isn't profitable in that case anyway.
if (!Succ->getSinglePredecessor()) {
  BasicBlock::iterator BBI = BB->begin();
  while (isa<PHINode>(*BBI)) {
    for (Use &U : BBI->uses()) {
      if (PHINode* PN = dyn_cast<PHINode>(U.getUser())) {
        if (PN->getIncomingBlock(U) != BB)
          return false;
      } else {
        return false;
      }
    }
    ++BBI;
  }
}

// We cannot fold the block if it's a branch to an already present callbr
// successor because that creates duplicate successors.
for (BasicBlock *PredBB : predecessors(BB)) {
  if (auto *CBI = dyn_cast<CallBrInst>(PredBB->getTerminator())) {
    if (Succ == CBI->getDefaultDest())
      return false;
    for (unsigned i = 0, e = CBI->getNumIndirectDests(); i != e; ++i)
      if (Succ == CBI->getIndirectDest(i))
        return false;
  }
}

LLVM_DEBUG(dbgs() << "Killing Trivial BB: \n" << *BB)do { } while (false);

SmallVector<DominatorTree::UpdateType, 32> Updates;
if (DTU) {
  // All predecessors of BB will be moved to Succ.
  SmallPtrSet<BasicBlock *, 8> PredsOfBB(pred_begin(BB), pred_end(BB));
  SmallPtrSet<BasicBlock *, 8> PredsOfSucc(pred_begin(Succ), pred_end(Succ));
  Updates.reserve(Updates.size() + 2 * PredsOfBB.size() + 1);
  for (auto *PredOfBB : PredsOfBB)
    // This predecessor of BB may already have Succ as a successor.
    if (!PredsOfSucc.contains(PredOfBB))
      Updates.push_back({DominatorTree::Insert, PredOfBB, Succ});
  for (auto *PredOfBB : PredsOfBB)
    Updates.push_back({DominatorTree::Delete, PredOfBB, BB});
  Updates.push_back({DominatorTree::Delete, BB, Succ});
}

if (isa<PHINode>(Succ->begin())) {
  // If there is more than one pred of succ, and there are PHI nodes in
  // the successor, then we need to add incoming edges for the PHI nodes
  //
  const PredBlockVector BBPreds(pred_begin(BB), pred_end(BB));

  // Loop over all of the PHI nodes in the successor of BB.
  for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
    PHINode *PN = cast<PHINode>(I);

    redirectValuesFromPredecessorsToPhi(BB, BBPreds, PN);
  }
}

if (Succ->getSinglePredecessor()) {
  // BB is the only predecessor of Succ, so Succ will end up with exactly
  // the same predecessors BB had.

  // Copy over any phi, debug or lifetime instruction.
  BB->getTerminator()->eraseFromParent();
  Succ->getInstList().splice(Succ->getFirstNonPHI()->getIterator(),
                             BB->getInstList());
} else {
  while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
    // We explicitly check for such uses in CanPropagatePredecessorsForPHIs.
    assert(PN->use_empty() && "There shouldn't be any uses here!")(static_cast<void> (0));
    PN->eraseFromParent();
  }
}

// If the unconditional branch we replaced contains llvm.loop metadata, we
// add the metadata to the branch instructions in the predecessors.
unsigned LoopMDKind = BB->getContext().getMDKindID("llvm.loop");
Instruction *TI = BB->getTerminator();
if (TI)
  if (MDNode *LoopMD = TI->getMetadata(LoopMDKind))
    for (BasicBlock *Pred : predecessors(BB))
      Pred->getTerminator()->setMetadata(LoopMDKind, LoopMD);

// Everything that jumped to BB now goes to Succ.
BB->replaceAllUsesWith(Succ);
if (!Succ->hasName()) Succ->takeName(BB);

// Clear the successor list of BB to match updates applying to DTU later.
if (BB->getTerminator())
  BB->getInstList().pop_back();
new UnreachableInst(BB->getContext(), BB);
assert(succ_empty(BB) && "The successor list of BB isn't empty before "(static_cast<void> (0))
                         "applying corresponding DTU updates.")(static_cast<void> (0));

if (DTU)
  DTU->applyUpdates(Updates);

DeleteDeadBlock(BB, DTU);

return true;
1168}

1170static bool EliminateDuplicatePHINodesNaiveImpl(BasicBlock *BB) {
// This implementation doesn't currently consider undef operands
// specially. Theoretically, two phis which are identical except for
// one having an undef where the other doesn't could be collapsed.

bool Changed = false;

// Examine each PHI.
// Note that increment of I must *NOT* be in the iteration_expression, since
// we don't want to immediately advance when we restart from the beginning.
for (auto I = BB->begin(); PHINode *PN = dyn_cast<PHINode>(I);) {
  ++I;
  // Is there an identical PHI node in this basic block?
  // Note that we only look in the upper square's triangle,
  // we already checked that the lower triangle PHI's aren't identical.
  for (auto J = I; PHINode *DuplicatePN = dyn_cast<PHINode>(J); ++J) {
    if (!DuplicatePN->isIdenticalToWhenDefined(PN))
      continue;
    // A duplicate. Replace this PHI with the base PHI.
    ++NumPHICSEs;
    DuplicatePN->replaceAllUsesWith(PN);
    DuplicatePN->eraseFromParent();
    Changed = true;

    // The RAUW can change PHIs that we already visited.
    I = BB->begin();
    break; // Start over from the beginning.
  }
}
return Changed;
1200}

1202static bool EliminateDuplicatePHINodesSetBasedImpl(BasicBlock *BB) {
// This implementation doesn't currently consider undef operands
// specially. Theoretically, two phis which are identical except for
// one having an undef where the other doesn't could be collapsed.

struct PHIDenseMapInfo {
  static PHINode *getEmptyKey() {
    return DenseMapInfo<PHINode *>::getEmptyKey();
  }

  static PHINode *getTombstoneKey() {
    return DenseMapInfo<PHINode *>::getTombstoneKey();
  }

  static bool isSentinel(PHINode *PN) {
    return PN == getEmptyKey() || PN == getTombstoneKey();
  }

  // WARNING: this logic must be kept in sync with
  //          Instruction::isIdenticalToWhenDefined()!
  static unsigned getHashValueImpl(PHINode *PN) {
    // Compute a hash value on the operands. Instcombine will likely have
    // sorted them, which helps expose duplicates, but we have to check all
    // the operands to be safe in case instcombine hasn't run.
    return static_cast<unsigned>(hash_combine(
        hash_combine_range(PN->value_op_begin(), PN->value_op_end()),
        hash_combine_range(PN->block_begin(), PN->block_end())));
  }

  static unsigned getHashValue(PHINode *PN) {
1232#ifndef NDEBUG1
    // If -phicse-debug-hash was specified, return a constant -- this
    // will force all hashing to collide, so we'll exhaustively search
    // the table for a match, and the assertion in isEqual will fire if
    // there's a bug causing equal keys to hash differently.
    if (PHICSEDebugHash)
      return 0;
1239#endif
    return getHashValueImpl(PN);
  }

  static bool isEqualImpl(PHINode *LHS, PHINode *RHS) {
    if (isSentinel(LHS) || isSentinel(RHS))
      return LHS == RHS;
    return LHS->isIdenticalTo(RHS);
  }

  static bool isEqual(PHINode *LHS, PHINode *RHS) {
    // These comparisons are nontrivial, so assert that equality implies
    // hash equality (DenseMap demands this as an invariant).
    bool Result = isEqualImpl(LHS, RHS);
    assert(!Result || (isSentinel(LHS) && LHS == RHS) ||(static_cast<void> (0))
           getHashValueImpl(LHS) == getHashValueImpl(RHS))(static_cast<void> (0));
    return Result;
  }
};

// Set of unique PHINodes.
DenseSet<PHINode *, PHIDenseMapInfo> PHISet;
PHISet.reserve(4 * PHICSENumPHISmallSize);

// Examine each PHI.
bool Changed = false;
for (auto I = BB->begin(); PHINode *PN = dyn_cast<PHINode>(I++);) {
  auto Inserted = PHISet.insert(PN);
  if (!Inserted.second) {
    // A duplicate. Replace this PHI with its duplicate.
    ++NumPHICSEs;
    PN->replaceAllUsesWith(*Inserted.first);
    PN->eraseFromParent();
    Changed = true;

    // The RAUW can change PHIs that we already visited. Start over from the
    // beginning.
    PHISet.clear();
    I = BB->begin();
  }
}

return Changed;
1282}

1284bool llvm::EliminateDuplicatePHINodes(BasicBlock *BB) {
if (
1286#ifndef NDEBUG1
    !PHICSEDebugHash &&
1288#endif
    hasNItemsOrLess(BB->phis(), PHICSENumPHISmallSize))
  return EliminateDuplicatePHINodesNaiveImpl(BB);
return EliminateDuplicatePHINodesSetBasedImpl(BB);
1292}

1294/// If the specified pointer points to an object that we control, try to modify
1295/// the object's alignment to PrefAlign. Returns a minimum known alignment of
1296/// the value after the operation, which may be lower than PrefAlign.
1297///
1298/// Increating value alignment isn't often possible though. If alignment is
1299/// important, a more reliable approach is to simply align all global variables
1300/// and allocation instructions to their preferred alignment from the beginning.
1301static Align tryEnforceAlignment(Value *V, Align PrefAlign,
                               const DataLayout &DL) {
V = V->stripPointerCasts();

if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
  // TODO: Ideally, this function would not be called if PrefAlign is smaller
  // than the current alignment, as the known bits calculation should have
  // already taken it into account. However, this is not always the case,
  // as computeKnownBits() has a depth limit, while stripPointerCasts()
  // doesn't.
  Align CurrentAlign = AI->getAlign();
  if (PrefAlign <= CurrentAlign)
    return CurrentAlign;

  // If the preferred alignment is greater than the natural stack alignment
  // then don't round up. This avoids dynamic stack realignment.
  if (DL.exceedsNaturalStackAlignment(PrefAlign))
    return CurrentAlign;
  AI->setAlignment(PrefAlign);
  return PrefAlign;
}

if (auto *GO = dyn_cast<GlobalObject>(V)) {
  // TODO: as above, this shouldn't be necessary.
  Align CurrentAlign = GO->getPointerAlignment(DL);
  if (PrefAlign <= CurrentAlign)
    return CurrentAlign;

  // If there is a large requested alignment and we can, bump up the alignment
  // of the global.  If the memory we set aside for the global may not be the
  // memory used by the final program then it is impossible for us to reliably
  // enforce the preferred alignment.
  if (!GO->canIncreaseAlignment())
    return CurrentAlign;

  GO->setAlignment(PrefAlign);
  return PrefAlign;
}

return Align(1);
1341}

1343Align llvm::getOrEnforceKnownAlignment(Value *V, MaybeAlign PrefAlign,
                                     const DataLayout &DL,
                                     const Instruction *CxtI,
                                     AssumptionCache *AC,
                                     const DominatorTree *DT) {
assert(V->getType()->isPointerTy() &&(static_cast<void> (0))
       "getOrEnforceKnownAlignment expects a pointer!")(static_cast<void> (0));

KnownBits Known = computeKnownBits(V, DL, 0, AC, CxtI, DT);
unsigned TrailZ = Known.countMinTrailingZeros();

// Avoid trouble with ridiculously large TrailZ values, such as
// those computed from a null pointer.
// LLVM doesn't support alignments larger than (1 << MaxAlignmentExponent).
TrailZ = std::min(TrailZ, +Value::MaxAlignmentExponent);

Align Alignment = Align(1ull << std::min(Known.getBitWidth() - 1, TrailZ));

if (PrefAlign && *PrefAlign > Alignment)
  Alignment = std::max(Alignment, tryEnforceAlignment(V, *PrefAlign, DL));

// We don't need to make any adjustment.
return Alignment;
1366}

1368///===---------------------------------------------------------------------===//
1369///  Dbg Intrinsic utilities
1370///

1372/// See if there is a dbg.value intrinsic for DIVar for the PHI node.
1373static bool PhiHasDebugValue(DILocalVariable *DIVar,
                           DIExpression *DIExpr,
                           PHINode *APN) {
// Since we can't guarantee that the original dbg.declare instrinsic
// is removed by LowerDbgDeclare(), we need to make sure that we are
// not inserting the same dbg.value intrinsic over and over.
SmallVector<DbgValueInst *, 1> DbgValues;
findDbgValues(DbgValues, APN);
for (auto *DVI : DbgValues) {
  assert(is_contained(DVI->getValues(), APN))(static_cast<void> (0));
  if ((DVI->getVariable() == DIVar) && (DVI->getExpression() == DIExpr))
    return true;
}
return false;
1387}

1389/// Check if the alloc size of \p ValTy is large enough to cover the variable
1390/// (or fragment of the variable) described by \p DII.
1391///
1392/// This is primarily intended as a helper for the different
1393/// ConvertDebugDeclareToDebugValue functions. The dbg.declare/dbg.addr that is
1394/// converted describes an alloca'd variable, so we need to use the
1395/// alloc size of the value when doing the comparison. E.g. an i1 value will be
1396/// identified as covering an n-bit fragment, if the store size of i1 is at
1397/// least n bits.
1398static bool valueCoversEntireFragment(Type *ValTy, DbgVariableIntrinsic *DII) {
const DataLayout &DL = DII->getModule()->getDataLayout();
TypeSize ValueSize = DL.getTypeAllocSizeInBits(ValTy);
if (Optional<uint64_t> FragmentSize = DII->getFragmentSizeInBits()) {
  assert(!ValueSize.isScalable() &&(static_cast<void> (0))
         "Fragments don't work on scalable types.")(static_cast<void> (0));
  return ValueSize.getFixedSize() >= *FragmentSize;
}
// We can't always calculate the size of the DI variable (e.g. if it is a
// VLA). Try to use the size of the alloca that the dbg intrinsic describes
// intead.
if (DII->isAddressOfVariable()) {
  // DII should have exactly 1 location when it is an address.
  assert(DII->getNumVariableLocationOps() == 1 &&(static_cast<void> (0))
         "address of variable must have exactly 1 location operand.")(static_cast<void> (0));
  if (auto *AI =
          dyn_cast_or_null<AllocaInst>(DII->getVariableLocationOp(0))) {
    if (Optional<TypeSize> FragmentSize = AI->getAllocationSizeInBits(DL)) {
      assert(ValueSize.isScalable() == FragmentSize->isScalable() &&(static_cast<void> (0))
             "Both sizes should agree on the scalable flag.")(static_cast<void> (0));
      return TypeSize::isKnownGE(ValueSize, *FragmentSize);
    }
  }
}
// Could not determine size of variable. Conservatively return false.
return false;
1424}

1426/// Produce a DebugLoc to use for each dbg.declare/inst pair that are promoted
1427/// to a dbg.value. Because no machine insts can come from debug intrinsics,
1428/// only the scope and inlinedAt is significant. Zero line numbers are used in
1429/// case this DebugLoc leaks into any adjacent instructions.
1430static DebugLoc getDebugValueLoc(DbgVariableIntrinsic *DII, Instruction *Src) {
// Original dbg.declare must have a location.
const DebugLoc &DeclareLoc = DII->getDebugLoc();
MDNode *Scope = DeclareLoc.getScope();
DILocation *InlinedAt = DeclareLoc.getInlinedAt();
// Produce an unknown location with the correct scope / inlinedAt fields.
return DILocation::get(DII->getContext(), 0, 0, Scope, InlinedAt);
1437}

1439/// Inserts a llvm.dbg.value intrinsic before a store to an alloca'd value
1440/// that has an associated llvm.dbg.declare or llvm.dbg.addr intrinsic.
1441void llvm::ConvertDebugDeclareToDebugValue(DbgVariableIntrinsic *DII,
                                         StoreInst *SI, DIBuilder &Builder) {
assert(DII->isAddressOfVariable())(static_cast<void> (0));
auto *DIVar = DII->getVariable();
assert(DIVar && "Missing variable")(static_cast<void> (0));
auto *DIExpr = DII->getExpression();
Value *DV = SI->getValueOperand();

DebugLoc NewLoc = getDebugValueLoc(DII, SI);

if (!valueCoversEntireFragment(DV->getType(), DII)) {
  // FIXME: If storing to a part of the variable described by the dbg.declare,
  // then we want to insert a dbg.value for the corresponding fragment.
  LLVM_DEBUG(dbgs() << "Failed to convert dbg.declare to dbg.value: "do { } while (false)
                    << *DII << '\n')do { } while (false);
  // For now, when there is a store to parts of the variable (but we do not
  // know which part) we insert an dbg.value instrinsic to indicate that we
  // know nothing about the variable's content.
  DV = UndefValue::get(DV->getType());
  Builder.insertDbgValueIntrinsic(DV, DIVar, DIExpr, NewLoc, SI);
  return;
}

Builder.insertDbgValueIntrinsic(DV, DIVar, DIExpr, NewLoc, SI);
1465}

1467/// Inserts a llvm.dbg.value intrinsic before a load of an alloca'd value
1468/// that has an associated llvm.dbg.declare or llvm.dbg.addr intrinsic.
1469void llvm::ConvertDebugDeclareToDebugValue(DbgVariableIntrinsic *DII,
                                         LoadInst *LI, DIBuilder &Builder) {
auto *DIVar = DII->getVariable();
auto *DIExpr = DII->getExpression();
assert(DIVar && "Missing variable")(static_cast<void> (0));

if (!valueCoversEntireFragment(LI->getType(), DII)) {
  // FIXME: If only referring to a part of the variable described by the
  // dbg.declare, then we want to insert a dbg.value for the corresponding
  // fragment.
  LLVM_DEBUG(dbgs() << "Failed to convert dbg.declare to dbg.value: "do { } while (false)
                    << *DII << '\n')do { } while (false);
  return;
}

DebugLoc NewLoc = getDebugValueLoc(DII, nullptr);

// We are now tracking the loaded value instead of the address. In the
// future if multi-location support is added to the IR, it might be
// preferable to keep tracking both the loaded value and the original
// address in case the alloca can not be elided.
Instruction *DbgValue = Builder.insertDbgValueIntrinsic(
    LI, DIVar, DIExpr, NewLoc, (Instruction *)nullptr);
DbgValue->insertAfter(LI);
1493}

1495/// Inserts a llvm.dbg.value intrinsic after a phi that has an associated
1496/// llvm.dbg.declare or llvm.dbg.addr intrinsic.
1497void llvm::ConvertDebugDeclareToDebugValue(DbgVariableIntrinsic *DII,
                                         PHINode *APN, DIBuilder &Builder) {
auto *DIVar = DII->getVariable();
auto *DIExpr = DII->getExpression();
assert(DIVar && "Missing variable")(static_cast<void> (0));

if (PhiHasDebugValue(DIVar, DIExpr, APN))
  return;

if (!valueCoversEntireFragment(APN->getType(), DII)) {
  // FIXME: If only referring to a part of the variable described by the
  // dbg.declare, then we want to insert a dbg.value for the corresponding
  // fragment.
  LLVM_DEBUG(dbgs() << "Failed to convert dbg.declare to dbg.value: "do { } while (false)
                    << *DII << '\n')do { } while (false);
  return;
}

BasicBlock *BB = APN->getParent();
auto InsertionPt = BB->getFirstInsertionPt();

DebugLoc NewLoc = getDebugValueLoc(DII, nullptr);

// The block may be a catchswitch block, which does not have a valid
// insertion point.
// FIXME: Insert dbg.value markers in the successors when appropriate.
if (InsertionPt != BB->end())
  Builder.insertDbgValueIntrinsic(APN, DIVar, DIExpr, NewLoc, &*InsertionPt);
1525}

1527/// Determine whether this alloca is either a VLA or an array.
1528static bool isArray(AllocaInst *AI) {
return AI->isArrayAllocation() ||
       (AI->getAllocatedType() && AI->getAllocatedType()->isArrayTy());
1531}

1533/// Determine whether this alloca is a structure.
1534static bool isStructure(AllocaInst *AI) {
return AI->getAllocatedType() && AI->getAllocatedType()->isStructTy();
1536}

1538/// LowerDbgDeclare - Lowers llvm.dbg.declare intrinsics into appropriate set
1539/// of llvm.dbg.value intrinsics.
1540bool llvm::LowerDbgDeclare(Function &F) {
bool Changed = false;
DIBuilder DIB(*F.getParent(), /*AllowUnresolved*/ false);
SmallVector<DbgDeclareInst *, 4> Dbgs;
for (auto &FI : F)
  for (Instruction &BI : FI)
    if (auto DDI = dyn_cast<DbgDeclareInst>(&BI))
      Dbgs.push_back(DDI);

if (Dbgs.empty())
  return Changed;

for (auto &I : Dbgs) {
  DbgDeclareInst *DDI = I;
  AllocaInst *AI = dyn_cast_or_null<AllocaInst>(DDI->getAddress());
  // If this is an alloca for a scalar variable, insert a dbg.value
  // at each load and store to the alloca and erase the dbg.declare.
  // The dbg.values allow tracking a variable even if it is not
  // stored on the stack, while the dbg.declare can only describe
  // the stack slot (and at a lexical-scope granularity). Later
  // passes will attempt to elide the stack slot.
  if (!AI || isArray(AI) || isStructure(AI))
    continue;

  // A volatile load/store means that the alloca can't be elided anyway.
  if (llvm::any_of(AI->users(), [](User *U) -> bool {
        if (LoadInst *LI = dyn_cast<LoadInst>(U))
          return LI->isVolatile();
        if (StoreInst *SI = dyn_cast<StoreInst>(U))
          return SI->isVolatile();
        return false;
      }))
    continue;

  SmallVector<const Value *, 8> WorkList;
  WorkList.push_back(AI);
  while (!WorkList.empty()) {
    const Value *V = WorkList.pop_back_val();
    for (auto &AIUse : V->uses()) {
      User *U = AIUse.getUser();
      if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
        if (AIUse.getOperandNo() == 1)
          ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
      } else if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
        ConvertDebugDeclareToDebugValue(DDI, LI, DIB);
      } else if (CallInst *CI = dyn_cast<CallInst>(U)) {
        // This is a call by-value or some other instruction that takes a
        // pointer to the variable. Insert a *value* intrinsic that describes
        // the variable by dereferencing the alloca.
        if (!CI->isLifetimeStartOrEnd()) {
          DebugLoc NewLoc = getDebugValueLoc(DDI, nullptr);
          auto *DerefExpr =
              DIExpression::append(DDI->getExpression(), dwarf::DW_OP_deref);
          DIB.insertDbgValueIntrinsic(AI, DDI->getVariable(), DerefExpr,
                                      NewLoc, CI);
        }
      } else if (BitCastInst *BI = dyn_cast<BitCastInst>(U)) {
        if (BI->getType()->isPointerTy())
          WorkList.push_back(BI);
      }
    }
  }
  DDI->eraseFromParent();
  Changed = true;
}

if (Changed)
for (BasicBlock &BB : F)
  RemoveRedundantDbgInstrs(&BB);

return Changed;
1611}

1613/// Propagate dbg.value intrinsics through the newly inserted PHIs.
1614void llvm::insertDebugValuesForPHIs(BasicBlock *BB,
                                  SmallVectorImpl<PHINode *> &InsertedPHIs) {
assert(BB && "No BasicBlock to clone dbg.value(s) from.")(static_cast<void> (0));
if (InsertedPHIs.size() == 0)
  return;

// Map existing PHI nodes to their dbg.values.
ValueToValueMapTy DbgValueMap;
for (auto &I : *BB) {
  if (auto DbgII = dyn_cast<DbgVariableIntrinsic>(&I)) {
    for (Value *V : DbgII->location_ops())
      if (auto *Loc = dyn_cast_or_null<PHINode>(V))
        DbgValueMap.insert({Loc, DbgII});
  }
}
if (DbgValueMap.size() == 0)
  return;

// Map a pair of the destination BB and old dbg.value to the new dbg.value,
// so that if a dbg.value is being rewritten to use more than one of the
// inserted PHIs in the same destination BB, we can update the same dbg.value
// with all the new PHIs instead of creating one copy for each.
MapVector<std::pair<BasicBlock *, DbgVariableIntrinsic *>,
          DbgVariableIntrinsic *>
    NewDbgValueMap;
// Then iterate through the new PHIs and look to see if they use one of the
// previously mapped PHIs. If so, create a new dbg.value intrinsic that will
// propagate the info through the new PHI. If we use more than one new PHI in
// a single destination BB with the same old dbg.value, merge the updates so
// that we get a single new dbg.value with all the new PHIs.
for (auto PHI : InsertedPHIs) {
  BasicBlock *Parent = PHI->getParent();
  // Avoid inserting an intrinsic into an EH block.
  if (Parent->getFirstNonPHI()->isEHPad())
    continue;
  for (auto VI : PHI->operand_values()) {
    auto V = DbgValueMap.find(VI);
    if (V != DbgValueMap.end()) {
      auto *DbgII = cast<DbgVariableIntrinsic>(V->second);
      auto NewDI = NewDbgValueMap.find({Parent, DbgII});
      if (NewDI == NewDbgValueMap.end()) {
        auto *NewDbgII = cast<DbgVariableIntrinsic>(DbgII->clone());
        NewDI = NewDbgValueMap.insert({{Parent, DbgII}, NewDbgII}).first;
      }
      DbgVariableIntrinsic *NewDbgII = NewDI->second;
      // If PHI contains VI as an operand more than once, we may
      // replaced it in NewDbgII; confirm that it is present.
      if (is_contained(NewDbgII->location_ops(), VI))
        NewDbgII->replaceVariableLocationOp(VI, PHI);
    }
  }
}
// Insert thew new dbg.values into their destination blocks.
for (auto DI : NewDbgValueMap) {
  BasicBlock *Parent = DI.first.first;
  auto *NewDbgII = DI.second;
  auto InsertionPt = Parent->getFirstInsertionPt();
  assert(InsertionPt != Parent->end() && "Ill-formed basic block")(static_cast<void> (0));
  NewDbgII->insertBefore(&*InsertionPt);
}
1674}

1676bool llvm::replaceDbgDeclare(Value *Address, Value *NewAddress,
                           DIBuilder &Builder, uint8_t DIExprFlags,
                           int Offset) {
auto DbgAddrs = FindDbgAddrUses(Address);
for (DbgVariableIntrinsic *DII : DbgAddrs) {
  const DebugLoc &Loc = DII->getDebugLoc();
  auto *DIVar = DII->getVariable();
  auto *DIExpr = DII->getExpression();
  assert(DIVar && "Missing variable")(static_cast<void> (0));
  DIExpr = DIExpression::prepend(DIExpr, DIExprFlags, Offset);
  // Insert llvm.dbg.declare immediately before DII, and remove old
  // llvm.dbg.declare.
  Builder.insertDeclare(NewAddress, DIVar, DIExpr, Loc, DII);
  DII->eraseFromParent();
}
return !DbgAddrs.empty();
1692}

1694static void replaceOneDbgValueForAlloca(DbgValueInst *DVI, Value *NewAddress,
                                      DIBuilder &Builder, int Offset) {
const DebugLoc &Loc = DVI->getDebugLoc();
auto *DIVar = DVI->getVariable();
auto *DIExpr = DVI->getExpression();
assert(DIVar && "Missing variable")(static_cast<void> (0));

// This is an alloca-based llvm.dbg.value. The first thing it should do with
// the alloca pointer is dereference it. Otherwise we don't know how to handle
// it and give up.
if (!DIExpr || DIExpr->getNumElements() < 1 ||
    DIExpr->getElement(0) != dwarf::DW_OP_deref)
  return;

// Insert the offset before the first deref.
// We could just change the offset argument of dbg.value, but it's unsigned...
if (Offset)
  DIExpr = DIExpression::prepend(DIExpr, 0, Offset);

Builder.insertDbgValueIntrinsic(NewAddress, DIVar, DIExpr, Loc, DVI);
DVI->eraseFromParent();
1715}

1717void llvm::replaceDbgValueForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
                                  DIBuilder &Builder, int Offset) {
if (auto *L = LocalAsMetadata::getIfExists(AI))
  if (auto *MDV = MetadataAsValue::getIfExists(AI->getContext(), L))
    for (Use &U : llvm::make_early_inc_range(MDV->uses()))
      if (auto *DVI = dyn_cast<DbgValueInst>(U.getUser()))
        replaceOneDbgValueForAlloca(DVI, NewAllocaAddress, Builder, Offset);
1724}

1726/// Where possible to salvage debug information for \p I do so
1727/// and return True. If not possible mark undef and return False.
1728void llvm::salvageDebugInfo(Instruction &I) {
SmallVector<DbgVariableIntrinsic *, 1> DbgUsers;
findDbgUsers(DbgUsers, &I);
salvageDebugInfoForDbgValues(I, DbgUsers);
1732}

1734void llvm::salvageDebugInfoForDbgValues(
  Instruction &I, ArrayRef<DbgVariableIntrinsic *> DbgUsers) {
// This is an arbitrary chosen limit on the maximum number of values we can
// salvage up to in a DIArgList, used for performance reasons.
const unsigned MaxDebugArgs = 16;
bool Salvaged = false;

for (auto *DII : DbgUsers) {
  // Do not add DW_OP_stack_value for DbgDeclare and DbgAddr, because they
  // are implicitly pointing out the value as a DWARF memory location
  // description.
  bool StackValue = isa<DbgValueInst>(DII);
  auto DIILocation = DII->location_ops();
  assert((static_cast<void> (0))
      is_contained(DIILocation, &I) &&(static_cast<void> (0))
      "DbgVariableIntrinsic must use salvaged instruction as its location")(static_cast<void> (0));
  SmallVector<Value *, 4> AdditionalValues;
  // `I` may appear more than once in DII's location ops, and each use of `I`
  // must be updated in the DIExpression and potentially have additional
  // values added; thus we call salvageDebugInfoImpl for each `I` instance in
  // DIILocation.
  Value *Op0 = nullptr;
  DIExpression *SalvagedExpr = DII->getExpression();
  auto LocItr = find(DIILocation, &I);
  while (SalvagedExpr && LocItr != DIILocation.end()) {
    SmallVector<uint64_t, 16> Ops;
    unsigned LocNo = std::distance(DIILocation.begin(), LocItr);
    uint64_t CurrentLocOps = SalvagedExpr->getNumLocationOperands();
    Op0 = salvageDebugInfoImpl(I, CurrentLocOps, Ops, AdditionalValues);
    if (!Op0)
      break;
    SalvagedExpr =
        DIExpression::appendOpsToArg(SalvagedExpr, Ops, LocNo, StackValue);
    LocItr = std::find(++LocItr, DIILocation.end(), &I);
  }
  // salvageDebugInfoImpl should fail on examining the first element of
  // DbgUsers, or none of them.
  if (!Op0)
    break;

  DII->replaceVariableLocationOp(&I, Op0);
  if (AdditionalValues.empty()) {
    DII->setExpression(SalvagedExpr);
  } else if (isa<DbgValueInst>(DII) &&
             DII->getNumVariableLocationOps() + AdditionalValues.size() <=
                 MaxDebugArgs) {
    DII->addVariableLocationOps(AdditionalValues, SalvagedExpr);
  } else {
    // Do not salvage using DIArgList for dbg.addr/dbg.declare, as it is
    // currently only valid for stack value expressions.
    // Also do not salvage if the resulting DIArgList would contain an
    // unreasonably large number of values.
    Value *Undef = UndefValue::get(I.getOperand(0)->getType());
    DII->replaceVariableLocationOp(I.getOperand(0), Undef);
  }
  LLVM_DEBUG(dbgs() << "SALVAGE: " << *DII << '\n')do { } while (false);
  Salvaged = true;
}

if (Salvaged)
  return;

for (auto *DII : DbgUsers) {
  Value *Undef = UndefValue::get(I.getType());
  DII->replaceVariableLocationOp(&I, Undef);
}
1800}

1802Value *getSalvageOpsForGEP(GetElementPtrInst *GEP, const DataLayout &DL,
                         uint64_t CurrentLocOps,
                         SmallVectorImpl<uint64_t> &Opcodes,
                         SmallVectorImpl<Value *> &AdditionalValues) {
unsigned BitWidth = DL.getIndexSizeInBits(GEP->getPointerAddressSpace());
// Rewrite a GEP into a DIExpression.
MapVector<Value *, APInt> VariableOffsets;
APInt ConstantOffset(BitWidth, 0);
if (!GEP->collectOffset(DL, BitWidth, VariableOffsets, ConstantOffset))
  return nullptr;
if (!VariableOffsets.empty() && !CurrentLocOps) {
  Opcodes.insert(Opcodes.begin(), {dwarf::DW_OP_LLVM_arg, 0});
  CurrentLocOps = 1;
}
for (auto Offset : VariableOffsets) {
  AdditionalValues.push_back(Offset.first);
  assert(Offset.second.isStrictlyPositive() &&(static_cast<void> (0))
         "Expected strictly positive multiplier for offset.")(static_cast<void> (0));
  Opcodes.append({dwarf::DW_OP_LLVM_arg, CurrentLocOps++, dwarf::DW_OP_constu,
                  Offset.second.getZExtValue(), dwarf::DW_OP_mul,
                  dwarf::DW_OP_plus});
}
DIExpression::appendOffset(Opcodes, ConstantOffset.getSExtValue());
return GEP->getOperand(0);
1826}

1828uint64_t getDwarfOpForBinOp(Instruction::BinaryOps Opcode) {
switch (Opcode) {
case Instruction::Add:
  return dwarf::DW_OP_plus;
case Instruction::Sub:
  return dwarf::DW_OP_minus;
case Instruction::Mul:
  return dwarf::DW_OP_mul;
case Instruction::SDiv:
  return dwarf::DW_OP_div;
case Instruction::SRem:
  return dwarf::DW_OP_mod;
case Instruction::Or:
  return dwarf::DW_OP_or;
case Instruction::And:
  return dwarf::DW_OP_and;
case Instruction::Xor:
  return dwarf::DW_OP_xor;
case Instruction::Shl:
  return dwarf::DW_OP_shl;
case Instruction::LShr:
  return dwarf::DW_OP_shr;
case Instruction::AShr:
  return dwarf::DW_OP_shra;
default:
  // TODO: Salvage from each kind of binop we know about.
  return 0;
}
1856}

1858Value *getSalvageOpsForBinOp(BinaryOperator *BI, uint64_t CurrentLocOps,
                           SmallVectorImpl<uint64_t> &Opcodes,
                           SmallVectorImpl<Value *> &AdditionalValues) {
// Handle binary operations with constant integer operands as a special case.
auto *ConstInt = dyn_cast<ConstantInt>(BI->getOperand(1));
// Values wider than 64 bits cannot be represented within a DIExpression.
if (ConstInt && ConstInt->getBitWidth() > 64)
  return nullptr;

Instruction::BinaryOps BinOpcode = BI->getOpcode();
// Push any Constant Int operand onto the expression stack.
if (ConstInt) {
  uint64_t Val = ConstInt->getSExtValue();
  // Add or Sub Instructions with a constant operand can potentially be
  // simplified.
  if (BinOpcode == Instruction::Add || BinOpcode == Instruction::Sub) {
    uint64_t Offset = BinOpcode == Instruction::Add ? Val : -int64_t(Val);
    DIExpression::appendOffset(Opcodes, Offset);
    return BI->getOperand(0);
  }
  Opcodes.append({dwarf::DW_OP_constu, Val});
} else {
  if (!CurrentLocOps) {
    Opcodes.append({dwarf::DW_OP_LLVM_arg, 0});
    CurrentLocOps = 1;
  }
  Opcodes.append({dwarf::DW_OP_LLVM_arg, CurrentLocOps});
  AdditionalValues.push_back(BI->getOperand(1));
}

// Add salvaged binary operator to expression stack, if it has a valid
// representation in a DIExpression.
uint64_t DwarfBinOp = getDwarfOpForBinOp(BinOpcode);
if (!DwarfBinOp)
  return nullptr;
Opcodes.push_back(DwarfBinOp);
return BI->getOperand(0);
1895}

1897Value *llvm::salvageDebugInfoImpl(Instruction &I, uint64_t CurrentLocOps,
                                SmallVectorImpl<uint64_t> &Ops,
                                SmallVectorImpl<Value *> &AdditionalValues) {
auto &M = *I.getModule();
auto &DL = M.getDataLayout();

if (auto *CI = dyn_cast<CastInst>(&I)) {
  Value *FromValue = CI->getOperand(0);
  // No-op casts are irrelevant for debug info.
  if (CI->isNoopCast(DL)) {
    return FromValue;
  }

  Type *Type = CI->getType();
  // Casts other than Trunc, SExt, or ZExt to scalar types cannot be salvaged.
  if (Type->isVectorTy() ||
      !(isa<TruncInst>(&I) || isa<SExtInst>(&I) || isa<ZExtInst>(&I)))
    return nullptr;

  unsigned FromTypeBitSize = FromValue->getType()->getScalarSizeInBits();
  unsigned ToTypeBitSize = Type->getScalarSizeInBits();

  auto ExtOps = DIExpression::getExtOps(FromTypeBitSize, ToTypeBitSize,
                                        isa<SExtInst>(&I));
  Ops.append(ExtOps.begin(), ExtOps.end());
  return FromValue;
}

if (auto *GEP = dyn_cast<GetElementPtrInst>(&I))
  return getSalvageOpsForGEP(GEP, DL, CurrentLocOps, Ops, AdditionalValues);
else if (auto *BI = dyn_cast<BinaryOperator>(&I)) {
  return getSalvageOpsForBinOp(BI, CurrentLocOps, Ops, AdditionalValues);
}
// *Not* to do: we should not attempt to salvage load instructions,
// because the validity and lifetime of a dbg.value containing
// DW_OP_deref becomes difficult to analyze. See PR40628 for examples.
return nullptr;
1934}

1936/// A replacement for a dbg.value expression.
1937using DbgValReplacement = Optional<DIExpression *>;

1939/// Point debug users of \p From to \p To using exprs given by \p RewriteExpr,
1940/// possibly moving/undefing users to prevent use-before-def. Returns true if
1941/// changes are made.
1942static bool rewriteDebugUsers(
  Instruction &From, Value &To, Instruction &DomPoint, DominatorTree &DT,
  function_ref<DbgValReplacement(DbgVariableIntrinsic &DII)> RewriteExpr) {
// Find debug users of From.
SmallVector<DbgVariableIntrinsic *, 1> Users;
findDbgUsers(Users, &From);
if (Users.empty())
  return false;

// Prevent use-before-def of To.
bool Changed = false;
SmallPtrSet<DbgVariableIntrinsic *, 1> UndefOrSalvage;
if (isa<Instruction>(&To)) {
  bool DomPointAfterFrom = From.getNextNonDebugInstruction() == &DomPoint;

  for (auto *DII : Users) {
    // It's common to see a debug user between From and DomPoint. Move it
    // after DomPoint to preserve the variable update without any reordering.
    if (DomPointAfterFrom && DII->getNextNonDebugInstruction() == &DomPoint) {
      LLVM_DEBUG(dbgs() << "MOVE:  " << *DII << '\n')do { } while (false);
      DII->moveAfter(&DomPoint);
      Changed = true;

    // Users which otherwise aren't dominated by the replacement value must
    // be salvaged or deleted.
    } else if (!DT.dominates(&DomPoint, DII)) {
      UndefOrSalvage.insert(DII);
    }
  }
}

// Update debug users without use-before-def risk.
for (auto *DII : Users) {
  if (UndefOrSalvage.count(DII))
    continue;

  DbgValReplacement DVR = RewriteExpr(*DII);
  if (!DVR)
    continue;

  DII->replaceVariableLocationOp(&From, &To);
  DII->setExpression(*DVR);
  LLVM_DEBUG(dbgs() << "REWRITE:  " << *DII << '\n')do { } while (false);
  Changed = true;
}

if (!UndefOrSalvage.empty()) {
  // Try to salvage the remaining debug users.
  salvageDebugInfo(From);
  Changed = true;
}

return Changed;
1995}

1997/// Check if a bitcast between a value of type \p FromTy to type \p ToTy would
1998/// losslessly preserve the bits and semantics of the value. This predicate is
1999/// symmetric, i.e swapping \p FromTy and \p ToTy should give the same result.
2000///
2001/// Note that Type::canLosslesslyBitCastTo is not suitable here because it
2002/// allows semantically unequivalent bitcasts, such as <2 x i64> -> <4 x i32>,
2003/// and also does not allow lossless pointer <-> integer conversions.
2004static bool isBitCastSemanticsPreserving(const DataLayout &DL, Type *FromTy,
                                       Type *ToTy) {
// Trivially compatible types.
if (FromTy == ToTy)
  return true;

// Handle compatible pointer <-> integer conversions.
if (FromTy->isIntOrPtrTy() && ToTy->isIntOrPtrTy()) {
  bool SameSize = DL.getTypeSizeInBits(FromTy) == DL.getTypeSizeInBits(ToTy);
  bool LosslessConversion = !DL.isNonIntegralPointerType(FromTy) &&
                            !DL.isNonIntegralPointerType(ToTy);
  return SameSize && LosslessConversion;
}

// TODO: This is not exhaustive.
return false;
2020}

2022bool llvm::replaceAllDbgUsesWith(Instruction &From, Value &To,
                               Instruction &DomPoint, DominatorTree &DT) {
// Exit early if From has no debug users.
if (!From.isUsedByMetadata())
  return false;

assert(&From != &To && "Can't replace something with itself")(static_cast<void> (0));

Type *FromTy = From.getType();
Type *ToTy = To.getType();

auto Identity = [&](DbgVariableIntrinsic &DII) -> DbgValReplacement {
  return DII.getExpression();
};

// Handle no-op conversions.
Module &M = *From.getModule();
const DataLayout &DL = M.getDataLayout();
if (isBitCastSemanticsPreserving(DL, FromTy, ToTy))
  return rewriteDebugUsers(From, To, DomPoint, DT, Identity);

// Handle integer-to-integer widening and narrowing.
// FIXME: Use DW_OP_convert when it's available everywhere.
if (FromTy->isIntegerTy() && ToTy->isIntegerTy()) {
  uint64_t FromBits = FromTy->getPrimitiveSizeInBits();
  uint64_t ToBits = ToTy->getPrimitiveSizeInBits();
  assert(FromBits != ToBits && "Unexpected no-op conversion")(static_cast<void> (0));

  // When the width of the result grows, assume that a debugger will only
  // access the low `FromBits` bits when inspecting the source variable.
  if (FromBits < ToBits)
    return rewriteDebugUsers(From, To, DomPoint, DT, Identity);

  // The width of the result has shrunk. Use sign/zero extension to describe
  // the source variable's high bits.
  auto SignOrZeroExt = [&](DbgVariableIntrinsic &DII) -> DbgValReplacement {
    DILocalVariable *Var = DII.getVariable();

    // Without knowing signedness, sign/zero extension isn't possible.
    auto Signedness = Var->getSignedness();
    if (!Signedness)
      return None;

    bool Signed = *Signedness == DIBasicType::Signedness::Signed;
    return DIExpression::appendExt(DII.getExpression(), ToBits, FromBits,
                                   Signed);
  };
  return rewriteDebugUsers(From, To, DomPoint, DT, SignOrZeroExt);
}

// TODO: Floating-point conversions, vectors.
return false;
2074}

2076std::pair<unsigned, unsigned>
2077llvm::removeAllNonTerminatorAndEHPadInstructions(BasicBlock *BB) {
unsigned NumDeadInst = 0;
unsigned NumDeadDbgInst = 0;
// Delete the instructions backwards, as it has a reduced likelihood of
// having to update as many def-use and use-def chains.
Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
while (EndInst != &BB->front()) {
  // Delete the next to last instruction.
  Instruction *Inst = &*--EndInst->getIterator();
  if (!Inst->use_empty() && !Inst->getType()->isTokenTy())
    Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
  if (Inst->isEHPad() || Inst->getType()->isTokenTy()) {
    EndInst = Inst;
    continue;
  }
  if (isa<DbgInfoIntrinsic>(Inst))
    ++NumDeadDbgInst;
  else
    ++NumDeadInst;
  Inst->eraseFromParent();
}
return {NumDeadInst, NumDeadDbgInst};
2099}

2101unsigned llvm::changeToUnreachable(Instruction *I, bool PreserveLCSSA,
                                 DomTreeUpdater *DTU,
                                 MemorySSAUpdater *MSSAU) {
BasicBlock *BB = I->getParent();

if (MSSAU)
  MSSAU->changeToUnreachable(I);

SmallSet<BasicBlock *, 8> UniqueSuccessors;

// Loop over all of the successors, removing BB's entry from any PHI
// nodes.
for (BasicBlock *Successor : successors(BB)) {
  Successor->removePredecessor(BB, PreserveLCSSA);
  if (DTU)
    UniqueSuccessors.insert(Successor);
}
auto *UI = new UnreachableInst(I->getContext(), I);
UI->setDebugLoc(I->getDebugLoc());

// All instructions after this are dead.
unsigned NumInstrsRemoved = 0;
BasicBlock::iterator BBI = I->getIterator(), BBE = BB->end();
while (BBI != BBE) {
  if (!BBI->use_empty())
    BBI->replaceAllUsesWith(UndefValue::get(BBI->getType()));
  BB->getInstList().erase(BBI++);
  ++NumInstrsRemoved;
}
if (DTU) {
  SmallVector<DominatorTree::UpdateType, 8> Updates;
  Updates.reserve(UniqueSuccessors.size());
  for (BasicBlock *UniqueSuccessor : UniqueSuccessors)
    Updates.push_back({DominatorTree::Delete, BB, UniqueSuccessor});
  DTU->applyUpdates(Updates);
}
return NumInstrsRemoved;
2138}

2140CallInst *llvm::createCallMatchingInvoke(InvokeInst *II) {
SmallVector<Value *, 8> Args(II->args());
SmallVector<OperandBundleDef, 1> OpBundles;
II->getOperandBundlesAsDefs(OpBundles);
CallInst *NewCall = CallInst::Create(II->getFunctionType(),
                                     II->getCalledOperand(), Args, OpBundles);
NewCall->setCallingConv(II->getCallingConv());
NewCall->setAttributes(II->getAttributes());
NewCall->setDebugLoc(II->getDebugLoc());
NewCall->copyMetadata(*II);

// If the invoke had profile metadata, try converting them for CallInst.
uint64_t TotalWeight;
if (NewCall->extractProfTotalWeight(TotalWeight)) {
  // Set the total weight if it fits into i32, otherwise reset.
  MDBuilder MDB(NewCall->getContext());
  auto NewWeights = uint32_t(TotalWeight) != TotalWeight
                        ? nullptr
                        : MDB.createBranchWeights({uint32_t(TotalWeight)});
  NewCall->setMetadata(LLVMContext::MD_prof, NewWeights);
}

return NewCall;
2163}

2165/// changeToCall - Convert the specified invoke into a normal call.
2166void llvm::changeToCall(InvokeInst *II, DomTreeUpdater *DTU) {
CallInst *NewCall = createCallMatchingInvoke(II);
NewCall->takeName(II);
NewCall->insertBefore(II);
II->replaceAllUsesWith(NewCall);

// Follow the call by a branch to the normal destination.
BasicBlock *NormalDestBB = II->getNormalDest();
BranchInst::Create(NormalDestBB, II);

// Update PHI nodes in the unwind destination
BasicBlock *BB = II->getParent();
BasicBlock *UnwindDestBB = II->getUnwindDest();
UnwindDestBB->removePredecessor(BB);
II->eraseFromParent();
if (DTU)
  DTU->applyUpdates({{DominatorTree::Delete, BB, UnwindDestBB}});
2183}

2185BasicBlock *llvm::changeToInvokeAndSplitBasicBlock(CallInst *CI,
                                                 BasicBlock *UnwindEdge,
                                                 DomTreeUpdater *DTU) {
BasicBlock *BB = CI->getParent();

// Convert this function call into an invoke instruction.  First, split the
// basic block.
BasicBlock *Split = SplitBlock(BB, CI, DTU, /*LI=*/nullptr, /*MSSAU*/ nullptr,
                               CI->getName() + ".noexc");

// Delete the unconditional branch inserted by SplitBlock
BB->getInstList().pop_back();

// Create the new invoke instruction.
SmallVector<Value *, 8> InvokeArgs(CI->args());
SmallVector<OperandBundleDef, 1> OpBundles;

CI->getOperandBundlesAsDefs(OpBundles);

// Note: we're round tripping operand bundles through memory here, and that
// can potentially be avoided with a cleverer API design that we do not have
// as of this time.

InvokeInst *II =
    InvokeInst::Create(CI->getFunctionType(), CI->getCalledOperand(), Split,
                       UnwindEdge, InvokeArgs, OpBundles, CI->getName(), BB);
II->setDebugLoc(CI->getDebugLoc());
II->setCallingConv(CI->getCallingConv());
II->setAttributes(CI->getAttributes());

if (DTU)
  DTU->applyUpdates({{DominatorTree::Insert, BB, UnwindEdge}});

// Make sure that anything using the call now uses the invoke!  This also
// updates the CallGraph if present, because it uses a WeakTrackingVH.
CI->replaceAllUsesWith(II);

// Delete the original call
Split->getInstList().pop_front();
return Split;
2225}

2227static bool markAliveBlocks(Function &F,
                          SmallPtrSetImpl<BasicBlock *> &Reachable,
                          DomTreeUpdater *DTU = nullptr) {
SmallVector<BasicBlock*, 128> Worklist;
BasicBlock *BB = &F.front();
Worklist.push_back(BB);
Reachable.insert(BB);
bool Changed = false;
do {
  BB = Worklist.pop_back_val();

  // Do a quick scan of the basic block, turning any obviously unreachable
  // instructions into LLVM unreachable insts.  The instruction combining pass
  // canonicalizes unreachable insts into stores to null or undef.
  for (Instruction &I : *BB) {
    if (auto *CI = dyn_cast<CallInst>(&I)) {
      Value *Callee = CI->getCalledOperand();
      // Handle intrinsic calls.
      if (Function *F = dyn_cast<Function>(Callee)) {
        auto IntrinsicID = F->getIntrinsicID();
        // Assumptions that are known to be false are equivalent to
        // unreachable. Also, if the condition is undefined, then we make the
        // choice most beneficial to the optimizer, and choose that to also be
        // unreachable.
        if (IntrinsicID == Intrinsic::assume) {
          if (match(CI->getArgOperand(0), m_CombineOr(m_Zero(), m_Undef()))) {
            // Don't insert a call to llvm.trap right before the unreachable.
            changeToUnreachable(CI, false, DTU);
            Changed = true;
            break;
          }
        } else if (IntrinsicID == Intrinsic::experimental_guard) {
          // A call to the guard intrinsic bails out of the current
          // compilation unit if the predicate passed to it is false. If the
          // predicate is a constant false, then we know the guard will bail
          // out of the current compile unconditionally, so all code following
          // it is dead.
          //
          // Note: unlike in llvm.assume, it is not "obviously profitable" for
          // guards to treat `undef` as `false` since a guard on `undef` can
          // still be useful for widening.
          if (match(CI->getArgOperand(0), m_Zero()))
            if (!isa<UnreachableInst>(CI->getNextNode())) {
              changeToUnreachable(CI->getNextNode(), false, DTU);
              Changed = true;
              break;
            }
        }
      } else if ((isa<ConstantPointerNull>(Callee) &&
                  !NullPointerIsDefined(CI->getFunction())) ||
                 isa<UndefValue>(Callee)) {
        changeToUnreachable(CI, false, DTU);
        Changed = true;
        break;
      }
      if (CI->doesNotReturn() && !CI->isMustTailCall()) {
        // If we found a call to a no-return function, insert an unreachable
        // instruction after it.  Make sure there isn't *already* one there
        // though.
        if (!isa<UnreachableInst>(CI->getNextNode())) {
          // Don't insert a call to llvm.trap right before the unreachable.
          changeToUnreachable(CI->getNextNode(), false, DTU);
          Changed = true;
        }
        break;
      }
    } else if (auto *SI = dyn_cast<StoreInst>(&I)) {
      // Store to undef and store to null are undefined and used to signal
      // that they should be changed to unreachable by passes that can't
      // modify the CFG.

      // Don't touch volatile stores.
      if (SI->isVolatile()) continue;

      Value *Ptr = SI->getOperand(1);

      if (isa<UndefValue>(Ptr) ||
          (isa<ConstantPointerNull>(Ptr) &&
           !NullPointerIsDefined(SI->getFunction(),
                                 SI->getPointerAddressSpace()))) {
        changeToUnreachable(SI, false, DTU);
        Changed = true;
        break;
      }
    }
  }

  Instruction *Terminator = BB->getTerminator();
  if (auto *II = dyn_cast<InvokeInst>(Terminator)) {
    // Turn invokes that call 'nounwind' functions into ordinary calls.
    Value *Callee = II->getCalledOperand();
    if ((isa<ConstantPointerNull>(Callee) &&
         !NullPointerIsDefined(BB->getParent())) ||
        isa<UndefValue>(Callee)) {
      changeToUnreachable(II, false, DTU);
      Changed = true;
    } else if (II->doesNotThrow() && canSimplifyInvokeNoUnwind(&F)) {
      if (II->use_empty() && II->onlyReadsMemory()) {
        // jump to the normal destination branch.
        BasicBlock *NormalDestBB = II->getNormalDest();
        BasicBlock *UnwindDestBB = II->getUnwindDest();
        BranchInst::Create(NormalDestBB, II);
        UnwindDestBB->removePredecessor(II->getParent());
        II->eraseFromParent();
        if (DTU)
          DTU->applyUpdates({{DominatorTree::Delete, BB, UnwindDestBB}});
      } else
        changeToCall(II, DTU);
      Changed = true;
    }
  } else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(Terminator)) {
    // Remove catchpads which cannot be reached.
    struct CatchPadDenseMapInfo {
      static CatchPadInst *getEmptyKey() {
        return DenseMapInfo<CatchPadInst *>::getEmptyKey();
      }

      static CatchPadInst *getTombstoneKey() {
        return DenseMapInfo<CatchPadInst *>::getTombstoneKey();
      }

      static unsigned getHashValue(CatchPadInst *CatchPad) {
        return static_cast<unsigned>(hash_combine_range(
            CatchPad->value_op_begin(), CatchPad->value_op_end()));
      }

      static bool isEqual(CatchPadInst *LHS, CatchPadInst *RHS) {
        if (LHS == getEmptyKey() || LHS == getTombstoneKey() ||
            RHS == getEmptyKey() || RHS == getTombstoneKey())
          return LHS == RHS;
        return LHS->isIdenticalTo(RHS);
      }
    };

    SmallDenseMap<BasicBlock *, int, 8> NumPerSuccessorCases;
    // Set of unique CatchPads.
    SmallDenseMap<CatchPadInst *, detail::DenseSetEmpty, 4,
                  CatchPadDenseMapInfo, detail::DenseSetPair<CatchPadInst *>>
        HandlerSet;
    detail::DenseSetEmpty Empty;
    for (CatchSwitchInst::handler_iterator I = CatchSwitch->handler_begin(),
                                           E = CatchSwitch->handler_end();
         I != E; ++I) {
      BasicBlock *HandlerBB = *I;
      if (DTU)
        ++NumPerSuccessorCases[HandlerBB];
      auto *CatchPad = cast<CatchPadInst>(HandlerBB->getFirstNonPHI());
      if (!HandlerSet.insert({CatchPad, Empty}).second) {
        if (DTU)
          --NumPerSuccessorCases[HandlerBB];
        CatchSwitch->removeHandler(I);
        --I;
        --E;
        Changed = true;
      }
    }
    if (DTU) {
      std::vector<DominatorTree::UpdateType> Updates;
      for (const std::pair<BasicBlock *, int> &I : NumPerSuccessorCases)
        if (I.second == 0)
          Updates.push_back({DominatorTree::Delete, BB, I.first});
      DTU->applyUpdates(Updates);
    }
  }

  Changed |= ConstantFoldTerminator(BB, true, nullptr, DTU);
  for (BasicBlock *Successor : successors(BB))
    if (Reachable.insert(Successor).second)
      Worklist.push_back(Successor);
} while (!Worklist.empty());
return Changed;
2398}

2400void llvm::removeUnwindEdge(BasicBlock *BB, DomTreeUpdater *DTU) {
Instruction *TI = BB->getTerminator();

if (auto *II = dyn_cast<InvokeInst>(TI)) {
  changeToCall(II, DTU);
  return;
}

Instruction *NewTI;
BasicBlock *UnwindDest;

if (auto *CRI = dyn_cast<CleanupReturnInst>(TI)) {
  NewTI = CleanupReturnInst::Create(CRI->getCleanupPad(), nullptr, CRI);
  UnwindDest = CRI->getUnwindDest();
} else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(TI)) {
  auto *NewCatchSwitch = CatchSwitchInst::Create(
      CatchSwitch->getParentPad(), nullptr, CatchSwitch->getNumHandlers(),
      CatchSwitch->getName(), CatchSwitch);
  for (BasicBlock *PadBB : CatchSwitch->handlers())
    NewCatchSwitch->addHandler(PadBB);

  NewTI = NewCatchSwitch;
  UnwindDest = CatchSwitch->getUnwindDest();
} else {
  llvm_unreachable("Could not find unwind successor")__builtin_unreachable();
}

NewTI->takeName(TI);
NewTI->setDebugLoc(TI->getDebugLoc());
UnwindDest->removePredecessor(BB);
TI->replaceAllUsesWith(NewTI);
TI->eraseFromParent();
if (DTU)
  DTU->applyUpdates({{DominatorTree::Delete, BB, UnwindDest}});
2434}

2436/// removeUnreachableBlocks - Remove blocks that are not reachable, even
2437/// if they are in a dead cycle.  Return true if a change was made, false
2438/// otherwise.
2439bool llvm::removeUnreachableBlocks(Function &F, DomTreeUpdater *DTU,
                                 MemorySSAUpdater *MSSAU) {
SmallPtrSet<BasicBlock *, 16> Reachable;
bool Changed = markAliveBlocks(F, Reachable, DTU);

// If there are unreachable blocks in the CFG...
if (Reachable.size() == F.size())
  return Changed;

assert(Reachable.size() < F.size())(static_cast<void> (0));

// Are there any blocks left to actually delete?
SmallSetVector<BasicBlock *, 8> BlocksToRemove;
for (BasicBlock &BB : F) {
  // Skip reachable basic blocks
  if (Reachable.count(&BB))
    continue;
  // Skip already-deleted blocks
  if (DTU && DTU->isBBPendingDeletion(&BB))
    continue;
  BlocksToRemove.insert(&BB);
}

if (BlocksToRemove.empty())
  return Changed;

Changed = true;
NumRemoved += BlocksToRemove.size();

if (MSSAU)
  MSSAU->removeBlocks(BlocksToRemove);

DeleteDeadBlocks(BlocksToRemove.takeVector(), DTU);

return Changed;
2474}

2476void llvm::combineMetadata(Instruction *K, const Instruction *J,
                         ArrayRef<unsigned> KnownIDs, bool DoesKMove) {
SmallVector<std::pair<unsigned, MDNode *>, 4> Metadata;
K->dropUnknownNonDebugMetadata(KnownIDs);
K->getAllMetadataOtherThanDebugLoc(Metadata);
for (const auto &MD : Metadata) {
  unsigned Kind = MD.first;
  MDNode *JMD = J->getMetadata(Kind);
  MDNode *KMD = MD.second;

  switch (Kind) {
    default:
      K->setMetadata(Kind, nullptr); // Remove unknown metadata
      break;
    case LLVMContext::MD_dbg:
      llvm_unreachable("getAllMetadataOtherThanDebugLoc returned a MD_dbg")__builtin_unreachable();
    case LLVMContext::MD_tbaa:
      K->setMetadata(Kind, MDNode::getMostGenericTBAA(JMD, KMD));
      break;
    case LLVMContext::MD_alias_scope:
      K->setMetadata(Kind, MDNode::getMostGenericAliasScope(JMD, KMD));
      break;
    case LLVMContext::MD_noalias:
    case LLVMContext::MD_mem_parallel_loop_access:
      K->setMetadata(Kind, MDNode::intersect(JMD, KMD));
      break;
    case LLVMContext::MD_access_group:
      K->setMetadata(LLVMContext::MD_access_group,
                     intersectAccessGroups(K, J));
      break;
    case LLVMContext::MD_range:

      // If K does move, use most generic range. Otherwise keep the range of
      // K.
      if (DoesKMove)
        // FIXME: If K does move, we should drop the range info and nonnull.
        //        Currently this function is used with DoesKMove in passes
        //        doing hoisting/sinking and the current behavior of using the
        //        most generic range is correct in those cases.
        K->setMetadata(Kind, MDNode::getMostGenericRange(JMD, KMD));
      break;
    case LLVMContext::MD_fpmath:
      K->setMetadata(Kind, MDNode::getMostGenericFPMath(JMD, KMD));
      break;
    case LLVMContext::MD_invariant_load:
      // Only set the !invariant.load if it is present in both instructions.
      K->setMetadata(Kind, JMD);
      break;
    case LLVMContext::MD_nonnull:
      // If K does move, keep nonull if it is present in both instructions.
      if (DoesKMove)
        K->setMetadata(Kind, JMD);
      break;
    case LLVMContext::MD_invariant_group:
      // Preserve !invariant.group in K.
      break;
    case LLVMContext::MD_align:
      K->setMetadata(Kind,
        MDNode::getMostGenericAlignmentOrDereferenceable(JMD, KMD));
      break;
    case LLVMContext::MD_dereferenceable:
    case LLVMContext::MD_dereferenceable_or_null:
      K->setMetadata(Kind,
        MDNode::getMostGenericAlignmentOrDereferenceable(JMD, KMD));
      break;
    case LLVMContext::MD_preserve_access_index:
      // Preserve !preserve.access.index in K.
      break;
  }
}
// Set !invariant.group from J if J has it. If both instructions have it
// then we will just pick it from J - even when they are different.
// Also make sure that K is load or store - f.e. combining bitcast with load
// could produce bitcast with invariant.group metadata, which is invalid.
// FIXME: we should try to preserve both invariant.group md if they are
// different, but right now instruction can only have one invariant.group.
if (auto *JMD = J->getMetadata(LLVMContext::MD_invariant_group))
  if (isa<LoadInst>(K) || isa<StoreInst>(K))
    K->setMetadata(LLVMContext::MD_invariant_group, JMD);
2555}

2557void llvm::combineMetadataForCSE(Instruction *K, const Instruction *J,
                               bool KDominatesJ) {
unsigned KnownIDs[] = {
    LLVMContext::MD_tbaa,            LLVMContext::MD_alias_scope,
    LLVMContext::MD_noalias,         LLVMContext::MD_range,
    LLVMContext::MD_invariant_load,  LLVMContext::MD_nonnull,
    LLVMContext::MD_invariant_group, LLVMContext::MD_align,
    LLVMContext::MD_dereferenceable,
    LLVMContext::MD_dereferenceable_or_null,
    LLVMContext::MD_access_group,    LLVMContext::MD_preserve_access_index};
combineMetadata(K, J, KnownIDs, KDominatesJ);
2568}

2570void llvm::copyMetadataForLoad(LoadInst &Dest, const LoadInst &Source) {
SmallVector<std::pair<unsigned, MDNode *>, 8> MD;
Source.getAllMetadata(MD);
MDBuilder MDB(Dest.getContext());
Type *NewType = Dest.getType();
const DataLayout &DL = Source.getModule()->getDataLayout();
for (const auto &MDPair : MD) {
  unsigned ID = MDPair.first;
  MDNode *N = MDPair.second;
  // Note, essentially every kind of metadata should be preserved here! This
  // routine is supposed to clone a load instruction changing *only its type*.
  // The only metadata it makes sense to drop is metadata which is invalidated
  // when the pointer type changes. This should essentially never be the case
  // in LLVM, but we explicitly switch over only known metadata to be
  // conservatively correct. If you are adding metadata to LLVM which pertains
  // to loads, you almost certainly want to add it here.
  switch (ID) {
  case LLVMContext::MD_dbg:
  case LLVMContext::MD_tbaa:
  case LLVMContext::MD_prof:
  case LLVMContext::MD_fpmath:
  case LLVMContext::MD_tbaa_struct:
  case LLVMContext::MD_invariant_load:
  case LLVMContext::MD_alias_scope:
  case LLVMContext::MD_noalias:
  case LLVMContext::MD_nontemporal:
  case LLVMContext::MD_mem_parallel_loop_access:
  case LLVMContext::MD_access_group:
    // All of these directly apply.
    Dest.setMetadata(ID, N);
    break;

  case LLVMContext::MD_nonnull:
    copyNonnullMetadata(Source, N, Dest);
    break;

  case LLVMContext::MD_align:
  case LLVMContext::MD_dereferenceable:
  case LLVMContext::MD_dereferenceable_or_null:
    // These only directly apply if the new type is also a pointer.
    if (NewType->isPointerTy())
      Dest.setMetadata(ID, N);
    break;

  case LLVMContext::MD_range:
    copyRangeMetadata(DL, Source, N, Dest);
    break;
  }
}
2619}

2621void llvm::patchReplacementInstruction(Instruction *I, Value *Repl) {
auto *ReplInst = dyn_cast<Instruction>(Repl);
if (!ReplInst)
  return;

// Patch the replacement so that it is not more restrictive than the value
// being replaced.
// Note that if 'I' is a load being replaced by some operation,
// for example, by an arithmetic operation, then andIRFlags()
// would just erase all math flags from the original arithmetic
// operation, which is clearly not wanted and not needed.
if (!isa<LoadInst>(I))
  ReplInst->andIRFlags(I);

// FIXME: If both the original and replacement value are part of the
// same control-flow region (meaning that the execution of one
// guarantees the execution of the other), then we can combine the
// noalias scopes here and do better than the general conservative
// answer used in combineMetadata().

// In general, GVN unifies expressions over different control-flow
// regions, and so we need a conservative combination of the noalias
// scopes.
static const unsigned KnownIDs[] = {
    LLVMContext::MD_tbaa,            LLVMContext::MD_alias_scope,
    LLVMContext::MD_noalias,         LLVMContext::MD_range,
    LLVMContext::MD_fpmath,          LLVMContext::MD_invariant_load,
    LLVMContext::MD_invariant_group, LLVMContext::MD_nonnull,
    LLVMContext::MD_access_group,    LLVMContext::MD_preserve_access_index};
combineMetadata(ReplInst, I, KnownIDs, false);
2651}

2653template <typename RootType, typename DominatesFn>
2654static unsigned replaceDominatedUsesWith(Value *From, Value *To,
                                       const RootType &Root,
                                       const DominatesFn &Dominates) {
assert(From->getType() == To->getType())(static_cast<void> (0));

unsigned Count = 0;
for (Value::use_iterator UI = From->use_begin(), UE = From->use_end();
     UI != UE;) {
  Use &U = *UI++;
  if (!Dominates(Root, U))
    continue;
  U.set(To);
  LLVM_DEBUG(dbgs() << "Replace dominated use of '" << From->getName()do { } while (false)
                    << "' as " << *To << " in " << *U << "\n")do { } while (false);
  ++Count;
}
return Count;
2671}

2673unsigned llvm::replaceNonLocalUsesWith(Instruction *From, Value *To) {
 assert(From->getType() == To->getType())(static_cast<void> (0));
 auto *BB = From->getParent();
 unsigned Count = 0;

for (Value::use_iterator UI = From->use_begin(), UE = From->use_end();
     UI != UE;) {
  Use &U = *UI++;
  auto *I = cast<Instruction>(U.getUser());
  if (I->getParent() == BB)
    continue;
  U.set(To);
  ++Count;
}
return Count;
2688}

2690unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
                                      DominatorTree &DT,
                                      const BasicBlockEdge &Root) {
auto Dominates = [&DT](const BasicBlockEdge &Root, const Use &U) {
  return DT.dominates(Root, U);
};
return ::replaceDominatedUsesWith(From, To, Root, Dominates);
2697}

2699unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
                                      DominatorTree &DT,
                                      const BasicBlock *BB) {
auto Dominates = [&DT](const BasicBlock *BB, const Use &U) {
  return DT.dominates(BB, U);
};
return ::replaceDominatedUsesWith(From, To, BB, Dominates);
2706}

2708bool llvm::callsGCLeafFunction(const CallBase *Call,
                             const TargetLibraryInfo &TLI) {
// Check if the function is specifically marked as a gc leaf function.
if (Call->hasFnAttr("gc-leaf-function"))
  return true;
if (const Function *F = Call->getCalledFunction()) {
  if (F->hasFnAttribute("gc-leaf-function"))
    return true;

  if (auto IID = F->getIntrinsicID()) {
    // Most LLVM intrinsics do not take safepoints.
    return IID != Intrinsic::experimental_gc_statepoint &&
           IID != Intrinsic::experimental_deoptimize &&
           IID != Intrinsic::memcpy_element_unordered_atomic &&
           IID != Intrinsic::memmove_element_unordered_atomic;
  }
}

// Lib calls can be materialized by some passes, and won't be
// marked as 'gc-leaf-function.' All available Libcalls are
// GC-leaf.
LibFunc LF;
if (TLI.getLibFunc(*Call, LF)) {
  return TLI.has(LF);
}

return false;
2735}

2737void llvm::copyNonnullMetadata(const LoadInst &OldLI, MDNode *N,
                             LoadInst &NewLI) {
auto *NewTy = NewLI.getType();

// This only directly applies if the new type is also a pointer.
if (NewTy->isPointerTy()) {
  NewLI.setMetadata(LLVMContext::MD_nonnull, N);
  return;
}

// The only other translation we can do is to integral loads with !range
// metadata.
if (!NewTy->isIntegerTy())
  return;

MDBuilder MDB(NewLI.getContext());
const Value *Ptr = OldLI.getPointerOperand();
auto *ITy = cast<IntegerType>(NewTy);
auto *NullInt = ConstantExpr::getPtrToInt(
    ConstantPointerNull::get(cast<PointerType>(Ptr->getType())), ITy);
auto *NonNullInt = ConstantExpr::getAdd(NullInt, ConstantInt::get(ITy, 1));
NewLI.setMetadata(LLVMContext::MD_range,
                  MDB.createRange(NonNullInt, NullInt));
2760}

2762void llvm::copyRangeMetadata(const DataLayout &DL, const LoadInst &OldLI,
                           MDNode *N, LoadInst &NewLI) {
auto *NewTy = NewLI.getType();

// Give up unless it is converted to a pointer where there is a single very
// valuable mapping we can do reliably.
// FIXME: It would be nice to propagate this in more ways, but the type
// conversions make it hard.
if (!NewTy->isPointerTy())
  return;

unsigned BitWidth = DL.getPointerTypeSizeInBits(NewTy);
if (!getConstantRangeFromMetadata(*N).contains(APInt(BitWidth, 0))) {
  MDNode *NN = MDNode::get(OldLI.getContext(), None);
  NewLI.setMetadata(LLVMContext::MD_nonnull, NN);
}
2778}

2780void llvm::dropDebugUsers(Instruction &I) {
SmallVector<DbgVariableIntrinsic *, 1> DbgUsers;
findDbgUsers(DbgUsers, &I);
for (auto *DII : DbgUsers)
  DII->eraseFromParent();
2785}

2787void llvm::hoistAllInstructionsInto(BasicBlock *DomBlock, Instruction *InsertPt,
                                  BasicBlock *BB) {
// Since we are moving the instructions out of its basic block, we do not
// retain their original debug locations (DILocations) and debug intrinsic
// instructions.
//
// Doing so would degrade the debugging experience and adversely affect the
// accuracy of profiling information.
//
// Currently, when hoisting the instructions, we take the following actions:
// - Remove their debug intrinsic instructions.
// - Set their debug locations to the values from the insertion point.
//
// As per PR39141 (comment #8), the more fundamental reason why the dbg.values
// need to be deleted, is because there will not be any instructions with a
// DILocation in either branch left after performing the transformation. We
// can only insert a dbg.value after the two branches are joined again.
//
// See PR38762, PR39243 for more details.
//
// TODO: Extend llvm.dbg.value to take more than one SSA Value (PR39141) to
// encode predicated DIExpressions that yield different results on different
// code paths.

for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE;) {
  Instruction *I = &*II;
  I->dropUndefImplyingAttrsAndUnknownMetadata();
  if (I->isUsedByMetadata())
    dropDebugUsers(*I);
  if (I->isDebugOrPseudoInst()) {
    // Remove DbgInfo and pseudo probe Intrinsics.
    II = I->eraseFromParent();
    continue;
  }
  I->setDebugLoc(InsertPt->getDebugLoc());
  ++II;
}
DomBlock->getInstList().splice(InsertPt->getIterator(), BB->getInstList(),
                               BB->begin(),
                               BB->getTerminator()->getIterator());
2827}

2829namespace {

2831/// A potential constituent of a bitreverse or bswap expression. See
2832/// collectBitParts for a fuller explanation.
2833struct BitPart {
BitPart(Value *P, unsigned BW) : Provider(P) {
  Provenance.resize(BW);
}

/// The Value that this is a bitreverse/bswap of.
Value *Provider;

/// The "provenance" of each bit. Provenance[A] = B means that bit A
/// in Provider becomes bit B in the result of this expression.
SmallVector<int8_t, 32> Provenance; // int8_t means max size is i128.

enum { Unset = -1 };
2846};

2848} // end anonymous namespace

2850/// Analyze the specified subexpression and see if it is capable of providing
2851/// pieces of a bswap or bitreverse. The subexpression provides a potential
2852/// piece of a bswap or bitreverse if it can be proved that each non-zero bit in
2853/// the output of the expression came from a corresponding bit in some other
2854/// value. This function is recursive, and the end result is a mapping of
2855/// bitnumber to bitnumber. It is the caller's responsibility to validate that
2856/// the bitnumber to bitnumber mapping is correct for a bswap or bitreverse.
2857///
2858/// For example, if the current subexpression if "(shl i32 %X, 24)" then we know
2859/// that the expression deposits the low byte of %X into the high byte of the
2860/// result and that all other bits are zero. This expression is accepted and a
2861/// BitPart is returned with Provider set to %X and Provenance[24-31] set to
2862/// [0-7].
2863///
2864/// For vector types, all analysis is performed at the per-element level. No
2865/// cross-element analysis is supported (shuffle/insertion/reduction), and all
2866/// constant masks must be splatted across all elements.
2867///
2868/// To avoid revisiting values, the BitPart results are memoized into the
2869/// provided map. To avoid unnecessary copying of BitParts, BitParts are
2870/// constructed in-place in the \c BPS map. Because of this \c BPS needs to
2871/// store BitParts objects, not pointers. As we need the concept of a nullptr
2872/// BitParts (Value has been analyzed and the analysis failed), we an Optional
2873/// type instead to provide the same functionality.
2874///
2875/// Because we pass around references into \c BPS, we must use a container that
2876/// does not invalidate internal references (std::map instead of DenseMap).
2877static const Optional<BitPart> &
2878collectBitParts(Value *V, bool MatchBSwaps, bool MatchBitReversals,
              std::map<Value *, Optional<BitPart>> &BPS, int Depth,
              bool &FoundRoot) {
auto I = BPS.find(V);
if (I != BPS.end())
  return I->second;

auto &Result = BPS[V] = None;
auto BitWidth = V->getType()->getScalarSizeInBits();

// Can't do integer/elements > 128 bits.
if (BitWidth > 128)
  return Result;

// Prevent stack overflow by limiting the recursion depth
if (Depth == BitPartRecursionMaxDepth) {
  LLVM_DEBUG(dbgs() << "collectBitParts max recursion depth reached.\n")do { } while (false);
  return Result;
}

if (auto *I = dyn_cast<Instruction>(V)) {
  Value *X, *Y;
  const APInt *C;

  // If this is an or instruction, it may be an inner node of the bswap.
  if (match(V, m_Or(m_Value(X), m_Value(Y)))) {
    // Check we have both sources and they are from the same provider.
    const auto &A = collectBitParts(X, MatchBSwaps, MatchBitReversals, BPS,
                                    Depth + 1, FoundRoot);
    if (!A || !A->Provider)
      return Result;

    const auto &B = collectBitParts(Y, MatchBSwaps, MatchBitReversals, BPS,
                                    Depth + 1, FoundRoot);
    if (!B || A->Provider != B->Provider)
      return Result;

    // Try and merge the two together.
    Result = BitPart(A->Provider, BitWidth);
    for (unsigned BitIdx = 0; BitIdx < BitWidth; ++BitIdx) {
      if (A->Provenance[BitIdx] != BitPart::Unset &&
          B->Provenance[BitIdx] != BitPart::Unset &&
          A->Provenance[BitIdx] != B->Provenance[BitIdx])
        return Result = None;

      if (A->Provenance[BitIdx] == BitPart::Unset)
        Result->Provenance[BitIdx] = B->Provenance[BitIdx];
      else
        Result->Provenance[BitIdx] = A->Provenance[BitIdx];
    }

    return Result;
  }

  // If this is a logical shift by a constant, recurse then shift the result.
  if (match(V, m_LogicalShift(m_Value(X), m_APInt(C)))) {
    const APInt &BitShift = *C;

    // Ensure the shift amount is defined.
    if (BitShift.uge(BitWidth))
      return Result;

    // For bswap-only, limit shift amounts to whole bytes, for an early exit.
    if (!MatchBitReversals && (BitShift.getZExtValue() % 8) != 0)
      return Result;

    const auto &Res = collectBitParts(X, MatchBSwaps, MatchBitReversals, BPS,
                                      Depth + 1, FoundRoot);
    if (!Res)
      return Result;
    Result = Res;

    // Perform the "shift" on BitProvenance.
    auto &P = Result->Provenance;
    if (I->getOpcode() == Instruction::Shl) {
      P.erase(std::prev(P.end(), BitShift.getZExtValue()), P.end());
      P.insert(P.begin(), BitShift.getZExtValue(), BitPart::Unset);
    } else {
      P.erase(P.begin(), std::next(P.begin(), BitShift.getZExtValue()));
      P.insert(P.end(), BitShift.getZExtValue(), BitPart::Unset);
    }

    return Result;
  }

  // If this is a logical 'and' with a mask that clears bits, recurse then
  // unset the appropriate bits.
  if (match(V, m_And(m_Value(X), m_APInt(C)))) {
    const APInt &AndMask = *C;

    // Check that the mask allows a multiple of 8 bits for a bswap, for an
    // early exit.
    unsigned NumMaskedBits = AndMask.countPopulation();
    if (!MatchBitReversals && (NumMaskedBits % 8) != 0)
      return Result;

    const auto &Res = collectBitParts(X, MatchBSwaps, MatchBitReversals, BPS,
                                      Depth + 1, FoundRoot);
    if (!Res)
      return Result;
    Result = Res;

    for (unsigned BitIdx = 0; BitIdx < BitWidth; ++BitIdx)
      // If the AndMask is zero for this bit, clear the bit.
      if (AndMask[BitIdx] == 0)
        Result->Provenance[BitIdx] = BitPart::Unset;
    return Result;
  }

  // If this is a zext instruction zero extend the result.
  if (match(V, m_ZExt(m_Value(X)))) {
    const auto &Res = collectBitParts(X, MatchBSwaps, MatchBitReversals, BPS,
                                      Depth + 1, FoundRoot);
    if (!Res)
      return Result;

    Result = BitPart(Res->Provider, BitWidth);
    auto NarrowBitWidth = X->getType()->getScalarSizeInBits();
    for (unsigned BitIdx = 0; BitIdx < NarrowBitWidth; ++BitIdx)
      Result->Provenance[BitIdx] = Res->Provenance[BitIdx];
    for (unsigned BitIdx = NarrowBitWidth; BitIdx < BitWidth; ++BitIdx)
      Result->Provenance[BitIdx] = BitPart::Unset;
    return Result;
  }

  // If this is a truncate instruction, extract the lower bits.
  if (match(V, m_Trunc(m_Value(X)))) {
    const auto &Res = collectBitParts(X, MatchBSwaps, MatchBitReversals, BPS,
                                      Depth + 1, FoundRoot);
    if (!Res)
      return Result;

    Result = BitPart(Res->Provider, BitWidth);
    for (unsigned BitIdx = 0; BitIdx < BitWidth; ++BitIdx)
      Result->Provenance[BitIdx] = Res->Provenance[BitIdx];
    return Result;
  }

  // BITREVERSE - most likely due to us previous matching a partial
  // bitreverse.
  if (match(V, m_BitReverse(m_Value(X)))) {
    const auto &Res = collectBitParts(X, MatchBSwaps, MatchBitReversals, BPS,
                                      Depth + 1, FoundRoot);
    if (!Res)
      return Result;

    Result = BitPart(Res->Provider, BitWidth);
    for (unsigned BitIdx = 0; BitIdx < BitWidth; ++BitIdx)
      Result->Provenance[(BitWidth - 1) - BitIdx] = Res->Provenance[BitIdx];
    return Result;
  }

  // BSWAP - most likely due to us previous matching a partial bswap.
  if (match(V, m_BSwap(m_Value(X)))) {
    const auto &Res = collectBitParts(X, MatchBSwaps, MatchBitReversals, BPS,
                                      Depth + 1, FoundRoot);
    if (!Res)
      return Result;

    unsigned ByteWidth = BitWidth / 8;
    Result = BitPart(Res->Provider, BitWidth);
    for (unsigned ByteIdx = 0; ByteIdx < ByteWidth; ++ByteIdx) {
      unsigned ByteBitOfs = ByteIdx * 8;
      for (unsigned BitIdx = 0; BitIdx < 8; ++BitIdx)
        Result->Provenance[(BitWidth - 8 - ByteBitOfs) + BitIdx] =
            Res->Provenance[ByteBitOfs + BitIdx];
    }
    return Result;
  }

  // Funnel 'double' shifts take 3 operands, 2 inputs and the shift
  // amount (modulo).
  // fshl(X,Y,Z): (X << (Z % BW)) | (Y >> (BW - (Z % BW)))
  // fshr(X,Y,Z): (X << (BW - (Z % BW))) | (Y >> (Z % BW))
  if (match(V, m_FShl(m_Value(X), m_Value(Y), m_APInt(C))) ||
      match(V, m_FShr(m_Value(X), m_Value(Y), m_APInt(C)))) {
    // We can treat fshr as a fshl by flipping the modulo amount.
    unsigned ModAmt = C->urem(BitWidth);
    if (cast<IntrinsicInst>(I)->getIntrinsicID() == Intrinsic::fshr)
      ModAmt = BitWidth - ModAmt;

    // For bswap-only, limit shift amounts to whole bytes, for an early exit.
    if (!MatchBitReversals && (ModAmt % 8) != 0)
      return Result;

    // Check we have both sources and they are from the same provider.
    const auto &LHS = collectBitParts(X, MatchBSwaps, MatchBitReversals, BPS,
                                      Depth + 1, FoundRoot);
    if (!LHS || !LHS->Provider)
      return Result;

    const auto &RHS = collectBitParts(Y, MatchBSwaps, MatchBitReversals, BPS,
                                      Depth + 1, FoundRoot);
    if (!RHS || LHS->Provider != RHS->Provider)
      return Result;

    unsigned StartBitRHS = BitWidth - ModAmt;
    Result = BitPart(LHS->Provider, BitWidth);
    for (unsigned BitIdx = 0; BitIdx < StartBitRHS; ++BitIdx)
      Result->Provenance[BitIdx + ModAmt] = LHS->Provenance[BitIdx];
    for (unsigned BitIdx = 0; BitIdx < ModAmt; ++BitIdx)
      Result->Provenance[BitIdx] = RHS->Provenance[BitIdx + StartBitRHS];
    return Result;
  }
}

// If we've already found a root input value then we're never going to merge
// these back together.
if (FoundRoot)
  return Result;

// Okay, we got to something that isn't a shift, 'or', 'and', etc. This must
// be the root input value to the bswap/bitreverse.
FoundRoot = true;
Result = BitPart(V, BitWidth);
for (unsigned BitIdx = 0; BitIdx < BitWidth; ++BitIdx)
  Result->Provenance[BitIdx] = BitIdx;
return Result;
3096}

3098static bool bitTransformIsCorrectForBSwap(unsigned From, unsigned To,
                                        unsigned BitWidth) {
if (From % 8 != To % 8)
  return false;
// Convert from bit indices to byte indices and check for a byte reversal.
From >>= 3;
To >>= 3;
BitWidth >>= 3;
return From == BitWidth - To - 1;
3107}

3109static bool bitTransformIsCorrectForBitReverse(unsigned From, unsigned To,
                                             unsigned BitWidth) {
return From == BitWidth - To - 1;
3112}

3114bool llvm::recognizeBSwapOrBitReverseIdiom(
  Instruction *I, bool MatchBSwaps, bool MatchBitReversals,
  SmallVectorImpl<Instruction *> &InsertedInsts) {
if (!match(I, m_Or(m_Value(), m_Value())) &&
    !match(I, m_FShl(m_Value(), m_Value(), m_Value())) &&
    !match(I, m_FShr(m_Value(), m_Value(), m_Value())))
  return false;
if (!MatchBSwaps && !MatchBitReversals)
1
Assuming 'MatchBSwaps' is true→
  return false;
Type *ITy = I->getType();
if (!ITy->isIntOrIntVectorTy() || ITy->getScalarSizeInBits() > 128)
2
←
Assuming the condition is false→
3
←
Taking false branch→
  return false;  // Can't do integer/elements > 128 bits.

Type *DemandedTy = ITy;
if (I->hasOneUse())
4
←
Taking false branch→
  if (auto *Trunc = dyn_cast<TruncInst>(I->user_back()))
    DemandedTy = Trunc->getType();

// Try to find all the pieces corresponding to the bswap.
bool FoundRoot = false;
std::map<Value *, Optional<BitPart>> BPS;
const auto &Res =
    collectBitParts(I, MatchBSwaps, MatchBitReversals, BPS, 0, FoundRoot);
if (!Res)
5
←
Assuming the condition is false→
6
←
Taking false branch→
  return false;
ArrayRef<int8_t> BitProvenance = Res->Provenance;
assert(all_of(BitProvenance,(static_cast<void> (0))
              [](int8_t I) { return I == BitPart::Unset || 0 <= I; }) &&(static_cast<void> (0))
       "Illegal bit provenance index")(static_cast<void> (0));

// If the upper bits are zero, then attempt to perform as a truncated op.
if (BitProvenance.back() == BitPart::Unset) {
7
←
Assuming the condition is false→
8
←
Taking false branch→
  while (!BitProvenance.empty() && BitProvenance.back() == BitPart::Unset)
    BitProvenance = BitProvenance.drop_back();
  if (BitProvenance.empty())
    return false; // TODO - handle null value?
  DemandedTy = Type::getIntNTy(I->getContext(), BitProvenance.size());
  if (auto *IVecTy = dyn_cast<VectorType>(ITy))
    DemandedTy = VectorType::get(DemandedTy, IVecTy);
}

// Check BitProvenance hasn't found a source larger than the result type.
unsigned DemandedBW = DemandedTy->getScalarSizeInBits();
if (DemandedBW > ITy->getScalarSizeInBits())
9
←
Assuming the condition is false→
10
←
Taking false branch→
  return false;

// Now, is the bit permutation correct for a bswap or a bitreverse? We can
// only byteswap values with an even number of bytes.
APInt DemandedMask = APInt::getAllOnesValue(DemandedBW);
bool OKForBSwap = MatchBSwaps10.1
'MatchBSwaps' is true
1
'MatchBSwaps' is true
 && (DemandedBW % 16) == 0;
11
←
Assuming the condition is true→
bool OKForBitReverse = MatchBitReversals;
for (unsigned BitIdx = 0;
     (BitIdx < DemandedBW) && (OKForBSwap || OKForBitReverse); ++BitIdx) {
12
←
Assuming 'BitIdx' is >= 'DemandedBW'→
  if (BitProvenance[BitIdx] == BitPart::Unset) {
    DemandedMask.clearBit(BitIdx);
    continue;
  }
  OKForBSwap &= bitTransformIsCorrectForBSwap(BitProvenance[BitIdx], BitIdx,
                                              DemandedBW);
  OKForBitReverse &= bitTransformIsCorrectForBitReverse(BitProvenance[BitIdx],
                                                        BitIdx, DemandedBW);
}

Intrinsic::ID Intrin;
if (OKForBSwap12.1
'OKForBSwap' is true
1
'OKForBSwap' is true
)
13
←
Taking true branch→
  Intrin = Intrinsic::bswap;
else if (OKForBitReverse)
  Intrin = Intrinsic::bitreverse;
else
  return false;

Function *F = Intrinsic::getDeclaration(I->getModule(), Intrin, DemandedTy);
Value *Provider = Res->Provider;

// We may need to truncate the provider.
if (DemandedTy != Provider->getType()) {
14
←
Assuming the condition is false→
15
←
Taking false branch→
  auto *Trunc =
      CastInst::CreateIntegerCast(Provider, DemandedTy, false, "trunc", I);
  InsertedInsts.push_back(Trunc);
  Provider = Trunc;
}

Instruction *Result = CallInst::Create(F, Provider, "rev", I);
InsertedInsts.push_back(Result);

if (!DemandedMask.isAllOnesValue()) {
16
←
Calling 'APInt::isAllOnesValue'→
  auto *Mask = ConstantInt::get(DemandedTy, DemandedMask);
  Result = BinaryOperator::Create(Instruction::And, Result, Mask, "mask", I);
  InsertedInsts.push_back(Result);
}

// We may need to zeroextend back to the result type.
if (ITy != Result->getType()) {
  auto *ExtInst = CastInst::CreateIntegerCast(Result, ITy, false, "zext", I);
  InsertedInsts.push_back(ExtInst);
}

return true;
3212}

3214// CodeGen has special handling for some string functions that may replace
3215// them with target-specific intrinsics.  Since that'd skip our interceptors
3216// in ASan/MSan/TSan/DFSan, and thus make us miss some memory accesses,
3217// we mark affected calls as NoBuiltin, which will disable optimization
3218// in CodeGen.
3219void llvm::maybeMarkSanitizerLibraryCallNoBuiltin(
  CallInst *CI, const TargetLibraryInfo *TLI) {
Function *F = CI->getCalledFunction();
LibFunc Func;
if (F && !F->hasLocalLinkage() && F->hasName() &&
    TLI->getLibFunc(F->getName(), Func) && TLI->hasOptimizedCodeGen(Func) &&
    !F->doesNotAccessMemory())
  CI->addFnAttr(Attribute::NoBuiltin);
3227}

3229bool llvm::canReplaceOperandWithVariable(const Instruction *I, unsigned OpIdx) {
// We can't have a PHI with a metadata type.
if (I->getOperand(OpIdx)->getType()->isMetadataTy())
  return false;

// Early exit.
if (!isa<Constant>(I->getOperand(OpIdx)))
  return true;

switch (I->getOpcode()) {
default:
  return true;
case Instruction::Call:
case Instruction::Invoke: {
  const auto &CB = cast<CallBase>(*I);

  // Can't handle inline asm. Skip it.
  if (CB.isInlineAsm())
    return false;

  // Constant bundle operands may need to retain their constant-ness for
  // correctness.
  if (CB.isBundleOperand(OpIdx))
    return false;

  if (OpIdx < CB.getNumArgOperands()) {
    // Some variadic intrinsics require constants in the variadic arguments,
    // which currently aren't markable as immarg.
    if (isa<IntrinsicInst>(CB) &&
        OpIdx >= CB.getFunctionType()->getNumParams()) {
      // This is known to be OK for stackmap.
      return CB.getIntrinsicID() == Intrinsic::experimental_stackmap;
    }

    // gcroot is a special case, since it requires a constant argument which
    // isn't also required to be a simple ConstantInt.
    if (CB.getIntrinsicID() == Intrinsic::gcroot)
      return false;

    // Some intrinsic operands are required to be immediates.
    return !CB.paramHasAttr(OpIdx, Attribute::ImmArg);
  }

  // It is never allowed to replace the call argument to an intrinsic, but it
  // may be possible for a call.
  return !isa<IntrinsicInst>(CB);
}
case Instruction::ShuffleVector:
  // Shufflevector masks are constant.
  return OpIdx != 2;
case Instruction::Switch:
case Instruction::ExtractValue:
  // All operands apart from the first are constant.
  return OpIdx == 0;
case Instruction::InsertValue:
  // All operands apart from the first and the second are constant.
  return OpIdx < 2;
case Instruction::Alloca:
  // Static allocas (constant size in the entry block) are handled by
  // prologue/epilogue insertion so they're free anyway. We definitely don't
  // want to make them non-constant.
  return !cast<AllocaInst>(I)->isStaticAlloca();
case Instruction::GetElementPtr:
  if (OpIdx == 0)
    return true;
  gep_type_iterator It = gep_type_begin(I);
  for (auto E = std::next(It, OpIdx); It != E; ++It)
    if (It.isStruct())
      return false;
  return true;
}
3300}

3302Value *llvm::invertCondition(Value *Condition) {
// First: Check if it's a constant
if (Constant *C = dyn_cast<Constant>(Condition))
  return ConstantExpr::getNot(C);

// Second: If the condition is already inverted, return the original value
Value *NotCondition;
if (match(Condition, m_Not(m_Value(NotCondition))))
  return NotCondition;

BasicBlock *Parent = nullptr;
Instruction *Inst = dyn_cast<Instruction>(Condition);
if (Inst)
  Parent = Inst->getParent();
else if (Argument *Arg = dyn_cast<Argument>(Condition))
  Parent = &Arg->getParent()->getEntryBlock();
assert(Parent && "Unsupported condition to invert")(static_cast<void> (0));

// Third: Check all the users for an invert
for (User *U : Condition->users())
  if (Instruction *I = dyn_cast<Instruction>(U))
    if (I->getParent() == Parent && match(I, m_Not(m_Specific(Condition))))
      return I;

// Last option: Create a new instruction
auto *Inverted =
    BinaryOperator::CreateNot(Condition, Condition->getName() + ".inv");
if (Inst && !isa<PHINode>(Inst))
  Inverted->insertAfter(Inst);
else
  Inverted->insertBefore(&*Parent->getFirstInsertionPt());
return Inverted;
3334}

3336bool llvm::inferAttributesFromOthers(Function &F) {
// Note: We explicitly check for attributes rather than using cover functions
// because some of the cover functions include the logic being implemented.

bool Changed = false;
// readnone + not convergent implies nosync
if (!F.hasFnAttribute(Attribute::NoSync) &&
    F.doesNotAccessMemory() && !F.isConvergent()) {
  F.setNoSync();
  Changed = true;
}

// readonly implies nofree
if (!F.hasFnAttribute(Attribute::NoFree) && F.onlyReadsMemory()) {
  F.setDoesNotFreeMemory();
  Changed = true;
}

// willreturn implies mustprogress
if (!F.hasFnAttribute(Attribute::MustProgress) && F.willReturn()) {
  F.setMustProgress();
  Changed = true;
}

// TODO: There are a bunch of cases of restrictive memory effects we
// can infer by inspecting arguments of argmemonly-ish functions.

return Changed;
3364}

←

/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include/llvm/ADT/APInt.h

1//===-- llvm/ADT/APInt.h - For Arbitrary Precision Integer -----*- C++ -*--===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8///
9/// \file
10/// This file implements a class to represent arbitrary precision
11/// integral constant values and operations on them.
12///
13//===----------------------------------------------------------------------===//

15#ifndef LLVM_ADT_APINT_H
16#define LLVM_ADT_APINT_H

18#include "llvm/Support/Compiler.h"
19#include "llvm/Support/MathExtras.h"
20#include <cassert>
21#include <climits>
22#include <cstring>
23#include <utility>

25namespace llvm {
26class FoldingSetNodeID;
27class StringRef;
28class hash_code;
29class raw_ostream;

31template <typename T> class SmallVectorImpl;
32template <typename T> class ArrayRef;
33template <typename T> class Optional;
34template <typename T> struct DenseMapInfo;

36class APInt;

38inline APInt operator-(APInt);

40//===----------------------------------------------------------------------===//
41//                              APInt Class
42//===----------------------------------------------------------------------===//

44/// Class for arbitrary precision integers.
45///
46/// APInt is a functional replacement for common case unsigned integer type like
47/// "unsigned", "unsigned long" or "uint64_t", but also allows non-byte-width
48/// integer sizes and large integer value types such as 3-bits, 15-bits, or more
49/// than 64-bits of precision. APInt provides a variety of arithmetic operators
50/// and methods to manipulate integer values of any bit-width. It supports both
51/// the typical integer arithmetic and comparison operations as well as bitwise
52/// manipulation.
53///
54/// The class has several invariants worth noting:
55///   * All bit, byte, and word positions are zero-based.
56///   * Once the bit width is set, it doesn't change except by the Truncate,
57///     SignExtend, or ZeroExtend operations.
58///   * All binary operators must be on APInt instances of the same bit width.
59///     Attempting to use these operators on instances with different bit
60///     widths will yield an assertion.
61///   * The value is stored canonically as an unsigned value. For operations
62///     where it makes a difference, there are both signed and unsigned variants
63///     of the operation. For example, sdiv and udiv. However, because the bit
64///     widths must be the same, operations such as Mul and Add produce the same
65///     results regardless of whether the values are interpreted as signed or
66///     not.
67///   * In general, the class tries to follow the style of computation that LLVM
68///     uses in its IR. This simplifies its use for LLVM.
69///
70class LLVM_NODISCARD[[clang::warn_unused_result]] APInt {
71public:
typedef uint64_t WordType;

/// This enum is used to hold the constants we needed for APInt.
enum : unsigned {
  /// Byte size of a word.
  APINT_WORD_SIZE = sizeof(WordType),
  /// Bits in a word.
  APINT_BITS_PER_WORD = APINT_WORD_SIZE * CHAR_BIT8
};

enum class Rounding {
  DOWN,
  TOWARD_ZERO,
  UP,
};

static constexpr WordType WORDTYPE_MAX = ~WordType(0);

90private:
/// This union is used to store the integer value. When the
/// integer bit-width <= 64, it uses VAL, otherwise it uses pVal.
union {
  uint64_t VAL;   ///< Used to store the <= 64 bits integer value.
  uint64_t *pVal; ///< Used to store the >64 bits integer value.
} U;

unsigned BitWidth; ///< The number of bits in this APInt.

friend struct DenseMapInfo<APInt>;

friend class APSInt;

/// Fast internal constructor
///
/// This constructor is used only internally for speed of construction of
/// temporaries. It is unsafe for general use so it is not public.
APInt(uint64_t *val, unsigned bits) : BitWidth(bits) {
  U.pVal = val;
}

/// Determine which word a bit is in.
///
/// \returns the word position for the specified bit position.
static unsigned whichWord(unsigned bitPosition) {
  return bitPosition / APINT_BITS_PER_WORD;
}

/// Determine which bit in a word a bit is in.
///
/// \returns the bit position in a word for the specified bit position
/// in the APInt.
static unsigned whichBit(unsigned bitPosition) {
  return bitPosition % APINT_BITS_PER_WORD;
}

/// Get a single bit mask.
///
/// \returns a uint64_t with only bit at "whichBit(bitPosition)" set
/// This method generates and returns a uint64_t (word) mask for a single
/// bit at a specific bit position. This is used to mask the bit in the
/// corresponding word.
static uint64_t maskBit(unsigned bitPosition) {
  return 1ULL << whichBit(bitPosition);
}

/// Clear unused high order bits
///
/// This method is used internally to clear the top "N" bits in the high order
/// word that are not used by the APInt. This is needed after the most
/// significant word is assigned a value to ensure that those bits are
/// zero'd out.
APInt &clearUnusedBits() {
  // Compute how many bits are used in the final word
  unsigned WordBits = ((BitWidth-1) % APINT_BITS_PER_WORD) + 1;

  // Mask out the high bits.
  uint64_t mask = WORDTYPE_MAX >> (APINT_BITS_PER_WORD - WordBits);
  if (isSingleWord())
    U.VAL &= mask;
  else
    U.pVal[getNumWords() - 1] &= mask;
  return *this;
}

/// Get the word corresponding to a bit position
/// \returns the corresponding word for the specified bit position.
uint64_t getWord(unsigned bitPosition) const {
  return isSingleWord() ? U.VAL : U.pVal[whichWord(bitPosition)];
}

/// Utility method to change the bit width of this APInt to new bit width,
/// allocating and/or deallocating as necessary. There is no guarantee on the
/// value of any bits upon return. Caller should populate the bits after.
void reallocate(unsigned NewBitWidth);

/// Convert a char array into an APInt
///
/// \param radix 2, 8, 10, 16, or 36
/// Converts a string into a number.  The string must be non-empty
/// and well-formed as a number of the given base. The bit-width
/// must be sufficient to hold the result.
///
/// This is used by the constructors that take string arguments.
///
/// StringRef::getAsInteger is superficially similar but (1) does
/// not assume that the string is well-formed and (2) grows the
/// result to hold the input.
void fromString(unsigned numBits, StringRef str, uint8_t radix);

/// An internal division function for dividing APInts.
///
/// This is used by the toString method to divide by the radix. It simply
/// provides a more convenient form of divide for internal use since KnuthDiv
/// has specific constraints on its inputs. If those constraints are not met
/// then it provides a simpler form of divide.
static void divide(const WordType *LHS, unsigned lhsWords,
                   const WordType *RHS, unsigned rhsWords, WordType *Quotient,
                   WordType *Remainder);

/// out-of-line slow case for inline constructor
void initSlowCase(uint64_t val, bool isSigned);

/// shared code between two array constructors
void initFromArray(ArrayRef<uint64_t> array);

/// out-of-line slow case for inline copy constructor
void initSlowCase(const APInt &that);

/// out-of-line slow case for shl
void shlSlowCase(unsigned ShiftAmt);

/// out-of-line slow case for lshr.
void lshrSlowCase(unsigned ShiftAmt);

/// out-of-line slow case for ashr.
void ashrSlowCase(unsigned ShiftAmt);

/// out-of-line slow case for operator=
void AssignSlowCase(const APInt &RHS);

/// out-of-line slow case for operator==
bool EqualSlowCase(const APInt &RHS) const LLVM_READONLY__attribute__((__pure__));

/// out-of-line slow case for countLeadingZeros
unsigned countLeadingZerosSlowCase() const LLVM_READONLY__attribute__((__pure__));

/// out-of-line slow case for countLeadingOnes.
unsigned countLeadingOnesSlowCase() const LLVM_READONLY__attribute__((__pure__));

/// out-of-line slow case for countTrailingZeros.
unsigned countTrailingZerosSlowCase() const LLVM_READONLY__attribute__((__pure__));

/// out-of-line slow case for countTrailingOnes
unsigned countTrailingOnesSlowCase() const LLVM_READONLY__attribute__((__pure__));

/// out-of-line slow case for countPopulation
unsigned countPopulationSlowCase() const LLVM_READONLY__attribute__((__pure__));

/// out-of-line slow case for intersects.
bool intersectsSlowCase(const APInt &RHS) const LLVM_READONLY__attribute__((__pure__));

/// out-of-line slow case for isSubsetOf.
bool isSubsetOfSlowCase(const APInt &RHS) const LLVM_READONLY__attribute__((__pure__));

/// out-of-line slow case for setBits.
void setBitsSlowCase(unsigned loBit, unsigned hiBit);

/// out-of-line slow case for flipAllBits.
void flipAllBitsSlowCase();

/// out-of-line slow case for operator&=.
void AndAssignSlowCase(const APInt& RHS);

/// out-of-line slow case for operator|=.
void OrAssignSlowCase(const APInt& RHS);

/// out-of-line slow case for operator^=.
void XorAssignSlowCase(const APInt& RHS);

/// Unsigned comparison. Returns -1, 0, or 1 if this APInt is less than, equal
/// to, or greater than RHS.
int compare(const APInt &RHS) const LLVM_READONLY__attribute__((__pure__));

/// Signed comparison. Returns -1, 0, or 1 if this APInt is less than, equal
/// to, or greater than RHS.
int compareSigned(const APInt &RHS) const LLVM_READONLY__attribute__((__pure__));

259public:
/// \name Constructors
/// @{

/// Create a new APInt of numBits width, initialized as val.
///
/// If isSigned is true then val is treated as if it were a signed value
/// (i.e. as an int64_t) and the appropriate sign extension to the bit width
/// will be done. Otherwise, no sign extension occurs (high order bits beyond
/// the range of val are zero filled).
///
/// \param numBits the bit width of the constructed APInt
/// \param val the initial value of the APInt
/// \param isSigned how to treat signedness of val
APInt(unsigned numBits, uint64_t val, bool isSigned = false)
    : BitWidth(numBits) {
  assert(BitWidth && "bitwidth too small")(static_cast<void> (0));
  if (isSingleWord()) {
    U.VAL = val;
    clearUnusedBits();
  } else {
    initSlowCase(val, isSigned);
  }
}

/// Construct an APInt of numBits width, initialized as bigVal[].
///
/// Note that bigVal.size() can be smaller or larger than the corresponding
/// bit width but any extraneous bits will be dropped.
///
/// \param numBits the bit width of the constructed APInt
/// \param bigVal a sequence of words to form the initial value of the APInt
APInt(unsigned numBits, ArrayRef<uint64_t> bigVal);

/// Equivalent to APInt(numBits, ArrayRef<uint64_t>(bigVal, numWords)), but
/// deprecated because this constructor is prone to ambiguity with the
/// APInt(unsigned, uint64_t, bool) constructor.
///
/// If this overload is ever deleted, care should be taken to prevent calls
/// from being incorrectly captured by the APInt(unsigned, uint64_t, bool)
/// constructor.
APInt(unsigned numBits, unsigned numWords, const uint64_t bigVal[]);

/// Construct an APInt from a string representation.
///
/// This constructor interprets the string \p str in the given radix. The
/// interpretation stops when the first character that is not suitable for the
/// radix is encountered, or the end of the string. Acceptable radix values
/// are 2, 8, 10, 16, and 36. It is an error for the value implied by the
/// string to require more bits than numBits.
///
/// \param numBits the bit width of the constructed APInt
/// \param str the string to be interpreted
/// \param radix the radix to use for the conversion
APInt(unsigned numBits, StringRef str, uint8_t radix);

/// Simply makes *this a copy of that.
/// Copy Constructor.
APInt(const APInt &that) : BitWidth(that.BitWidth) {
  if (isSingleWord())
    U.VAL = that.U.VAL;
  else
    initSlowCase(that);
}

/// Move Constructor.
APInt(APInt &&that) : BitWidth(that.BitWidth) {
  memcpy(&U, &that.U, sizeof(U));
  that.BitWidth = 0;
}

/// Destructor.
~APInt() {
  if (needsCleanup())
    delete[] U.pVal;
}

/// Default constructor that creates an uninteresting APInt
/// representing a 1-bit zero value.
///
/// This is useful for object deserialization (pair this with the static
///  method Read).
explicit APInt() : BitWidth(1) { U.VAL = 0; }

/// Returns whether this instance allocated memory.
bool needsCleanup() const { return !isSingleWord(); }

/// Used to insert APInt objects, or objects that contain APInt objects, into
///  FoldingSets.
void Profile(FoldingSetNodeID &id) const;

/// @}
/// \name Value Tests
/// @{

/// Determine if this APInt just has one word to store value.
///
/// \returns true if the number of bits <= 64, false otherwise.
bool isSingleWord() const { return BitWidth <= APINT_BITS_PER_WORD; }
18
←
Returning the value 1, which participates in a condition later→

/// Determine sign of this APInt.
///
/// This tests the high bit of this APInt to determine if it is set.
///
/// \returns true if this APInt is negative, false otherwise
bool isNegative() const { return (*this)[BitWidth - 1]; }

/// Determine if this APInt Value is non-negative (>= 0)
///
/// This tests the high bit of the APInt to determine if it is unset.
bool isNonNegative() const { return !isNegative(); }

/// Determine if sign bit of this APInt is set.
///
/// This tests the high bit of this APInt to determine if it is set.
///
/// \returns true if this APInt has its sign bit set, false otherwise.
bool isSignBitSet() const { return (*this)[BitWidth-1]; }

/// Determine if sign bit of this APInt is clear.
///
/// This tests the high bit of this APInt to determine if it is clear.
///
/// \returns true if this APInt has its sign bit clear, false otherwise.
bool isSignBitClear() const { return !isSignBitSet(); }

/// Determine if this APInt Value is positive.
///
/// This tests if the value of this APInt is positive (> 0). Note
/// that 0 is not a positive value.
///
/// \returns true if this APInt is positive.
bool isStrictlyPositive() const { return isNonNegative() && !isNullValue(); }

/// Determine if this APInt Value is non-positive (<= 0).
///
/// \returns true if this APInt is non-positive.
bool isNonPositive() const { return !isStrictlyPositive(); }

/// Determine if all bits are set
///
/// This checks to see if the value has all bits of the APInt are set or not.
bool isAllOnesValue() const {
  if (isSingleWord())
17
←
Calling 'APInt::isSingleWord'→
19
←
Returning from 'APInt::isSingleWord'→
20
←
Taking true branch→
    return U.VAL == WORDTYPE_MAX >> (APINT_BITS_PER_WORD - BitWidth);
21
←
The result of the right shift is undefined due to shifting by '64', which is greater or equal to the width of type 'llvm::APInt::WordType'
  return countTrailingOnesSlowCase() == BitWidth;
}

/// Determine if all bits are clear
///
/// This checks to see if the value has all bits of the APInt are clear or
/// not.
bool isNullValue() const { return !*this; }

/// Determine if this is a value of 1.
///
/// This checks to see if the value of this APInt is one.
bool isOneValue() const {
  if (isSingleWord())
    return U.VAL == 1;
  return countLeadingZerosSlowCase() == BitWidth - 1;
}

/// Determine if this is the largest unsigned value.
///
/// This checks to see if the value of this APInt is the maximum unsigned
/// value for the APInt's bit width.
bool isMaxValue() const { return isAllOnesValue(); }

/// Determine if this is the largest signed value.
///
/// This checks to see if the value of this APInt is the maximum signed
/// value for the APInt's bit width.
bool isMaxSignedValue() const {
  if (isSingleWord())
    return U.VAL == ((WordType(1) << (BitWidth - 1)) - 1);
  return !isNegative() && countTrailingOnesSlowCase() == BitWidth - 1;
}

/// Determine if this is the smallest unsigned value.
///
/// This checks to see if the value of this APInt is the minimum unsigned
/// value for the APInt's bit width.
bool isMinValue() const { return isNullValue(); }

/// Determine if this is the smallest signed value.
///
/// This checks to see if the value of this APInt is the minimum signed
/// value for the APInt's bit width.
bool isMinSignedValue() const {
  if (isSingleWord())
    return U.VAL == (WordType(1) << (BitWidth - 1));
  return isNegative() && countTrailingZerosSlowCase() == BitWidth - 1;
}

/// Check if this APInt has an N-bits unsigned integer value.
bool isIntN(unsigned N) const {
  assert(N && "N == 0 ???")(static_cast<void> (0));
  return getActiveBits() <= N;
}

/// Check if this APInt has an N-bits signed integer value.
bool isSignedIntN(unsigned N) const {
  assert(N && "N == 0 ???")(static_cast<void> (0));
  return getMinSignedBits() <= N;
}

/// Check if this APInt's value is a power of two greater than zero.
///
/// \returns true if the argument APInt value is a power of two > 0.
bool isPowerOf2() const {
  if (isSingleWord())
    return isPowerOf2_64(U.VAL);
  return countPopulationSlowCase() == 1;
}

/// Check if the APInt's value is returned by getSignMask.
///
/// \returns true if this is the value returned by getSignMask.
bool isSignMask() const { return isMinSignedValue(); }

/// Convert APInt to a boolean value.
///
/// This converts the APInt to a boolean value as a test against zero.
bool getBoolValue() const { return !!*this; }

/// If this value is smaller than the specified limit, return it, otherwise
/// return the limit value.  This causes the value to saturate to the limit.
uint64_t getLimitedValue(uint64_t Limit = UINT64_MAX(18446744073709551615UL)) const {
  return ugt(Limit) ? Limit : getZExtValue();
}

/// Check if the APInt consists of a repeated bit pattern.
///
/// e.g. 0x01010101 satisfies isSplat(8).
/// \param SplatSizeInBits The size of the pattern in bits. Must divide bit
/// width without remainder.
bool isSplat(unsigned SplatSizeInBits) const;

/// \returns true if this APInt value is a sequence of \param numBits ones
/// starting at the least significant bit with the remainder zero.
bool isMask(unsigned numBits) const {
  assert(numBits != 0 && "numBits must be non-zero")(static_cast<void> (0));
  assert(numBits <= BitWidth && "numBits out of range")(static_cast<void> (0));
  if (isSingleWord())
    return U.VAL == (WORDTYPE_MAX >> (APINT_BITS_PER_WORD - numBits));
  unsigned Ones = countTrailingOnesSlowCase();
  return (numBits == Ones) &&
         ((Ones + countLeadingZerosSlowCase()) == BitWidth);
}

/// \returns true if this APInt is a non-empty sequence of ones starting at
/// the least significant bit with the remainder zero.
/// Ex. isMask(0x0000FFFFU) == true.
bool isMask() const {
  if (isSingleWord())
    return isMask_64(U.VAL);
  unsigned Ones = countTrailingOnesSlowCase();
  return (Ones > 0) && ((Ones + countLeadingZerosSlowCase()) == BitWidth);
}

/// Return true if this APInt value contains a sequence of ones with
/// the remainder zero.
bool isShiftedMask() const {
  if (isSingleWord())
    return isShiftedMask_64(U.VAL);
  unsigned Ones = countPopulationSlowCase();
  unsigned LeadZ = countLeadingZerosSlowCase();
  return (Ones + LeadZ + countTrailingZeros()) == BitWidth;
}

/// @}
/// \name Value Generators
/// @{

/// Gets maximum unsigned value of APInt for specific bit width.
static APInt getMaxValue(unsigned numBits) {
  return getAllOnesValue(numBits);
}

/// Gets maximum signed value of APInt for a specific bit width.
static APInt getSignedMaxValue(unsigned numBits) {
  APInt API = getAllOnesValue(numBits);
  API.clearBit(numBits - 1);
  return API;
}

/// Gets minimum unsigned value of APInt for a specific bit width.
static APInt getMinValue(unsigned numBits) { return APInt(numBits, 0); }

/// Gets minimum signed value of APInt for a specific bit width.
static APInt getSignedMinValue(unsigned numBits) {
  APInt API(numBits, 0);
  API.setBit(numBits - 1);
  return API;
}

/// Get the SignMask for a specific bit width.
///
/// This is just a wrapper function of getSignedMinValue(), and it helps code
/// readability when we want to get a SignMask.
static APInt getSignMask(unsigned BitWidth) {
  return getSignedMinValue(BitWidth);
}

/// Get the all-ones value.
///
/// \returns the all-ones value for an APInt of the specified bit-width.
static APInt getAllOnesValue(unsigned numBits) {
  return APInt(numBits, WORDTYPE_MAX, true);
}

/// Get the '0' value.
///
/// \returns the '0' value for an APInt of the specified bit-width.
static APInt getNullValue(unsigned numBits) { return APInt(numBits, 0); }

/// Compute an APInt containing numBits highbits from this APInt.
///
/// Get an APInt with the same BitWidth as this APInt, just zero mask
/// the low bits and right shift to the least significant bit.
///
/// \returns the high "numBits" bits of this APInt.
APInt getHiBits(unsigned numBits) const;

/// Compute an APInt containing numBits lowbits from this APInt.
///
/// Get an APInt with the same BitWidth as this APInt, just zero mask
/// the high bits.
///
/// \returns the low "numBits" bits of this APInt.
APInt getLoBits(unsigned numBits) const;

/// Return an APInt with exactly one bit set in the result.
static APInt getOneBitSet(unsigned numBits, unsigned BitNo) {
  APInt Res(numBits, 0);
  Res.setBit(BitNo);
  return Res;
}

/// Get a value with a block of bits set.
///
/// Constructs an APInt value that has a contiguous range of bits set. The
/// bits from loBit (inclusive) to hiBit (exclusive) will be set. All other
/// bits will be zero. For example, with parameters(32, 0, 16) you would get
/// 0x0000FFFF. Please call getBitsSetWithWrap if \p loBit may be greater than
/// \p hiBit.
///
/// \param numBits the intended bit width of the result
/// \param loBit the index of the lowest bit set.
/// \param hiBit the index of the highest bit set.
///
/// \returns An APInt value with the requested bits set.
static APInt getBitsSet(unsigned numBits, unsigned loBit, unsigned hiBit) {
  assert(loBit <= hiBit && "loBit greater than hiBit")(static_cast<void> (0));
  APInt Res(numBits, 0);
  Res.setBits(loBit, hiBit);
  return Res;
}

/// Wrap version of getBitsSet.
/// If \p hiBit is bigger than \p loBit, this is same with getBitsSet.
/// If \p hiBit is not bigger than \p loBit, the set bits "wrap". For example,
/// with parameters (32, 28, 4), you would get 0xF000000F.
/// If \p hiBit is equal to \p loBit, you would get a result with all bits
/// set.
static APInt getBitsSetWithWrap(unsigned numBits, unsigned loBit,
                                unsigned hiBit) {
  APInt Res(numBits, 0);
  Res.setBitsWithWrap(loBit, hiBit);
  return Res;
}

/// Get a value with upper bits starting at loBit set.
///
/// Constructs an APInt value that has a contiguous range of bits set. The
/// bits from loBit (inclusive) to numBits (exclusive) will be set. All other
/// bits will be zero. For example, with parameters(32, 12) you would get
/// 0xFFFFF000.
///
/// \param numBits the intended bit width of the result
/// \param loBit the index of the lowest bit to set.
///
/// \returns An APInt value with the requested bits set.
static APInt getBitsSetFrom(unsigned numBits, unsigned loBit) {
  APInt Res(numBits, 0);
  Res.setBitsFrom(loBit);
  return Res;
}

/// Get a value with high bits set
///
/// Constructs an APInt value that has the top hiBitsSet bits set.
///
/// \param numBits the bitwidth of the result
/// \param hiBitsSet the number of high-order bits set in the result.
static APInt getHighBitsSet(unsigned numBits, unsigned hiBitsSet) {
  APInt Res(numBits, 0);
  Res.setHighBits(hiBitsSet);
  return Res;
}

/// Get a value with low bits set
///
/// Constructs an APInt value that has the bottom loBitsSet bits set.
///
/// \param numBits the bitwidth of the result
/// \param loBitsSet the number of low-order bits set in the result.
static APInt getLowBitsSet(unsigned numBits, unsigned loBitsSet) {
  APInt Res(numBits, 0);
  Res.setLowBits(loBitsSet);
  return Res;
}

/// Return a value containing V broadcasted over NewLen bits.
static APInt getSplat(unsigned NewLen, const APInt &V);

/// Determine if two APInts have the same value, after zero-extending
/// one of them (if needed!) to ensure that the bit-widths match.
static bool isSameValue(const APInt &I1, const APInt &I2) {
  if (I1.getBitWidth() == I2.getBitWidth())
    return I1 == I2;

  if (I1.getBitWidth() > I2.getBitWidth())
    return I1 == I2.zext(I1.getBitWidth());

  return I1.zext(I2.getBitWidth()) == I2;
}

/// Overload to compute a hash_code for an APInt value.
friend hash_code hash_value(const APInt &Arg);

/// This function returns a pointer to the internal storage of the APInt.
/// This is useful for writing out the APInt in binary form without any
/// conversions.
const uint64_t *getRawData() const {
  if (isSingleWord())
    return &U.VAL;
  return &U.pVal[0];
}

/// @}
/// \name Unary Operators
/// @{

/// Postfix increment operator.
///
/// Increments *this by 1.
///
/// \returns a new APInt value representing the original value of *this.
APInt operator++(int) {
  APInt API(*this);
  ++(*this);
  return API;
}

/// Prefix increment operator.
///
/// \returns *this incremented by one
APInt &operator++();

/// Postfix decrement operator.
///
/// Decrements *this by 1.
///
/// \returns a new APInt value representing the original value of *this.
APInt operator--(int) {
  APInt API(*this);
  --(*this);
  return API;
}

/// Prefix decrement operator.
///
/// \returns *this decremented by one.
APInt &operator--();

/// Logical negation operator.
///
/// Performs logical negation operation on this APInt.
///
/// \returns true if *this is zero, false otherwise.
bool operator!() const {
  if (isSingleWord())
    return U.VAL == 0;
  return countLeadingZerosSlowCase() == BitWidth;
}

/// @}
/// \name Assignment Operators
/// @{

/// Copy assignment operator.
///
/// \returns *this after assignment of RHS.
APInt &operator=(const APInt &RHS) {
  // If the bitwidths are the same, we can avoid mucking with memory
  if (isSingleWord() && RHS.isSingleWord()) {
    U.VAL = RHS.U.VAL;
    BitWidth = RHS.BitWidth;
    return clearUnusedBits();
  }

  AssignSlowCase(RHS);
  return *this;
}

/// Move assignment operator.
APInt &operator=(APInt &&that) {
768#ifdef EXPENSIVE_CHECKS
  // Some std::shuffle implementations still do self-assignment.
  if (this == &that)
    return *this;
772#endif
  assert(this != &that && "Self-move not supported")(static_cast<void> (0));
  if (!isSingleWord())
    delete[] U.pVal;

  // Use memcpy so that type based alias analysis sees both VAL and pVal
  // as modified.
  memcpy(&U, &that.U, sizeof(U));

  BitWidth = that.BitWidth;
  that.BitWidth = 0;

  return *this;
}

/// Assignment operator.
///
/// The RHS value is assigned to *this. If the significant bits in RHS exceed
/// the bit width, the excess bits are truncated. If the bit width is larger
/// than 64, the value is zero filled in the unspecified high order bits.
///
/// \returns *this after assignment of RHS value.
APInt &operator=(uint64_t RHS) {
  if (isSingleWord()) {
    U.VAL = RHS;
    return clearUnusedBits();
  }
  U.pVal[0] = RHS;
  memset(U.pVal + 1, 0, (getNumWords() - 1) * APINT_WORD_SIZE);
  return *this;
}

/// Bitwise AND assignment operator.
///
/// Performs a bitwise AND operation on this APInt and RHS. The result is
/// assigned to *this.
///
/// \returns *this after ANDing with RHS.
APInt &operator&=(const APInt &RHS) {
  assert(BitWidth == RHS.BitWidth && "Bit widths must be the same")(static_cast<void> (0));
  if (isSingleWord())
    U.VAL &= RHS.U.VAL;
  else
    AndAssignSlowCase(RHS);
  return *this;
}

/// Bitwise AND assignment operator.
///
/// Performs a bitwise AND operation on this APInt and RHS. RHS is
/// logically zero-extended or truncated to match the bit-width of
/// the LHS.
APInt &operator&=(uint64_t RHS) {
  if (isSingleWord()) {
    U.VAL &= RHS;
    return *this;
  }
  U.pVal[0] &= RHS;
  memset(U.pVal+1, 0, (getNumWords() - 1) * APINT_WORD_SIZE);
  return *this;
}

/// Bitwise OR assignment operator.
///
/// Performs a bitwise OR operation on this APInt and RHS. The result is
/// assigned *this;
///
/// \returns *this after ORing with RHS.
APInt &operator|=(const APInt &RHS) {
  assert(BitWidth == RHS.BitWidth && "Bit widths must be the same")(static_cast<void> (0));
  if (isSingleWord())
    U.VAL |= RHS.U.VAL;
  else
    OrAssignSlowCase(RHS);
  return *this;
}

/// Bitwise OR assignment operator.
///
/// Performs a bitwise OR operation on this APInt and RHS. RHS is
/// logically zero-extended or truncated to match the bit-width of
/// the LHS.
APInt &operator|=(uint64_t RHS) {
  if (isSingleWord()) {
    U.VAL |= RHS;
    return clearUnusedBits();
  }
  U.pVal[0] |= RHS;
  return *this;
}

/// Bitwise XOR assignment operator.
///
/// Performs a bitwise XOR operation on this APInt and RHS. The result is
/// assigned to *this.
///
/// \returns *this after XORing with RHS.
APInt &operator^=(const APInt &RHS) {
  assert(BitWidth == RHS.BitWidth && "Bit widths must be the same")(static_cast<void> (0));
  if (isSingleWord())
    U.VAL ^= RHS.U.VAL;
  else
    XorAssignSlowCase(RHS);
  return *this;
}

/// Bitwise XOR assignment operator.
///
/// Performs a bitwise XOR operation on this APInt and RHS. RHS is
/// logically zero-extended or truncated to match the bit-width of
/// the LHS.
APInt &operator^=(uint64_t RHS) {
  if (isSingleWord()) {
    U.VAL ^= RHS;
    return clearUnusedBits();
  }
  U.pVal[0] ^= RHS;
  return *this;
}

/// Multiplication assignment operator.
///
/// Multiplies this APInt by RHS and assigns the result to *this.
///
/// \returns *this
APInt &operator*=(const APInt &RHS);
APInt &operator*=(uint64_t RHS);

/// Addition assignment operator.
///
/// Adds RHS to *this and assigns the result to *this.
///
/// \returns *this
APInt &operator+=(const APInt &RHS);
APInt &operator+=(uint64_t RHS);

/// Subtraction assignment operator.
///
/// Subtracts RHS from *this and assigns the result to *this.
///
/// \returns *this
APInt &operator-=(const APInt &RHS);
APInt &operator-=(uint64_t RHS);

/// Left-shift assignment function.
///
/// Shifts *this left by shiftAmt and assigns the result to *this.
///
/// \returns *this after shifting left by ShiftAmt
APInt &operator<<=(unsigned ShiftAmt) {
  assert(ShiftAmt <= BitWidth && "Invalid shift amount")(static_cast<void> (0));
  if (isSingleWord()) {
    if (ShiftAmt == BitWidth)
      U.VAL = 0;
    else
      U.VAL <<= ShiftAmt;
    return clearUnusedBits();
  }
  shlSlowCase(ShiftAmt);
  return *this;
}

/// Left-shift assignment function.
///
/// Shifts *this left by shiftAmt and assigns the result to *this.
///
/// \returns *this after shifting left by ShiftAmt
APInt &operator<<=(const APInt &ShiftAmt);

/// @}
/// \name Binary Operators
/// @{

/// Multiplication operator.
///
/// Multiplies this APInt by RHS and returns the result.
APInt operator*(const APInt &RHS) const;

/// Left logical shift operator.
///
/// Shifts this APInt left by \p Bits and returns the result.
APInt operator<<(unsigned Bits) const { return shl(Bits); }

/// Left logical shift operator.
///
/// Shifts this APInt left by \p Bits and returns the result.
APInt operator<<(const APInt &Bits) const { return shl(Bits); }

/// Arithmetic right-shift function.
///
/// Arithmetic right-shift this APInt by shiftAmt.
APInt ashr(unsigned ShiftAmt) const {
  APInt R(*this);
  R.ashrInPlace(ShiftAmt);
  return R;
}

/// Arithmetic right-shift this APInt by ShiftAmt in place.
void ashrInPlace(unsigned ShiftAmt) {
  assert(ShiftAmt <= BitWidth && "Invalid shift amount")(static_cast<void> (0));
  if (isSingleWord()) {
    int64_t SExtVAL = SignExtend64(U.VAL, BitWidth);
    if (ShiftAmt == BitWidth)
      U.VAL = SExtVAL >> (APINT_BITS_PER_WORD - 1); // Fill with sign bit.
    else
      U.VAL = SExtVAL >> ShiftAmt;
    clearUnusedBits();
    return;
  }
  ashrSlowCase(ShiftAmt);
}

/// Logical right-shift function.
///
/// Logical right-shift this APInt by shiftAmt.
APInt lshr(unsigned shiftAmt) const {
  APInt R(*this);
  R.lshrInPlace(shiftAmt);
  return R;
}

/// Logical right-shift this APInt by ShiftAmt in place.
void lshrInPlace(unsigned ShiftAmt) {
  assert(ShiftAmt <= BitWidth && "Invalid shift amount")(static_cast<void> (0));
  if (isSingleWord()) {
    if (ShiftAmt == BitWidth)
      U.VAL = 0;
    else
      U.VAL >>= ShiftAmt;
    return;
  }
  lshrSlowCase(ShiftAmt);
}

/// Left-shift function.
///
/// Left-shift this APInt by shiftAmt.
APInt shl(unsigned shiftAmt) const {
  APInt R(*this);
  R <<= shiftAmt;
  return R;
}

/// Rotate left by rotateAmt.
APInt rotl(unsigned rotateAmt) const;

/// Rotate right by rotateAmt.
APInt rotr(unsigned rotateAmt) const;

/// Arithmetic right-shift function.
///
/// Arithmetic right-shift this APInt by shiftAmt.
APInt ashr(const APInt &ShiftAmt) const {
  APInt R(*this);
  R.ashrInPlace(ShiftAmt);
  return R;
}

/// Arithmetic right-shift this APInt by shiftAmt in place.
void ashrInPlace(const APInt &shiftAmt);

/// Logical right-shift function.
///
/// Logical right-shift this APInt by shiftAmt.
APInt lshr(const APInt &ShiftAmt) const {
  APInt R(*this);
  R.lshrInPlace(ShiftAmt);
  return R;
}

/// Logical right-shift this APInt by ShiftAmt in place.
void lshrInPlace(const APInt &ShiftAmt);

/// Left-shift function.
///
/// Left-shift this APInt by shiftAmt.
APInt shl(const APInt &ShiftAmt) const {
  APInt R(*this);
  R <<= ShiftAmt;
  return R;
}

/// Rotate left by rotateAmt.
APInt rotl(const APInt &rotateAmt) const;

/// Rotate right by rotateAmt.
APInt rotr(const APInt &rotateAmt) const;

/// Unsigned division operation.
///
/// Perform an unsigned divide operation on this APInt by RHS. Both this and
/// RHS are treated as unsigned quantities for purposes of this division.
///
/// \returns a new APInt value containing the division result, rounded towards
/// zero.
APInt udiv(const APInt &RHS) const;
APInt udiv(uint64_t RHS) const;

/// Signed division function for APInt.
///
/// Signed divide this APInt by APInt RHS.
///
/// The result is rounded towards zero.
APInt sdiv(const APInt &RHS) const;
APInt sdiv(int64_t RHS) const;

/// Unsigned remainder operation.
///
/// Perform an unsigned remainder operation on this APInt with RHS being the
/// divisor. Both this and RHS are treated as unsigned quantities for purposes
/// of this operation. Note that this is a true remainder operation and not a
/// modulo operation because the sign follows the sign of the dividend which
/// is *this.
///
/// \returns a new APInt value containing the remainder result
APInt urem(const APInt &RHS) const;
uint64_t urem(uint64_t RHS) const;

/// Function for signed remainder operation.
///
/// Signed remainder operation on APInt.
APInt srem(const APInt &RHS) const;
int64_t srem(int64_t RHS) const;

/// Dual division/remainder interface.
///
/// Sometimes it is convenient to divide two APInt values and obtain both the
/// quotient and remainder. This function does both operations in the same
/// computation making it a little more efficient. The pair of input arguments
/// may overlap with the pair of output arguments. It is safe to call
/// udivrem(X, Y, X, Y), for example.
static void udivrem(const APInt &LHS, const APInt &RHS, APInt &Quotient,
                    APInt &Remainder);
static void udivrem(const APInt &LHS, uint64_t RHS, APInt &Quotient,
                    uint64_t &Remainder);

static void sdivrem(const APInt &LHS, const APInt &RHS, APInt &Quotient,
                    APInt &Remainder);
static void sdivrem(const APInt &LHS, int64_t RHS, APInt &Quotient,
                    int64_t &Remainder);

// Operations that return overflow indicators.
APInt sadd_ov(const APInt &RHS, bool &Overflow) const;
APInt uadd_ov(const APInt &RHS, bool &Overflow) const;
APInt ssub_ov(const APInt &RHS, bool &Overflow) const;
APInt usub_ov(const APInt &RHS, bool &Overflow) const;
APInt sdiv_ov(const APInt &RHS, bool &Overflow) const;
APInt smul_ov(const APInt &RHS, bool &Overflow) const;
APInt umul_ov(const APInt &RHS, bool &Overflow) const;
APInt sshl_ov(const APInt &Amt, bool &Overflow) const;
APInt ushl_ov(const APInt &Amt, bool &Overflow) const;

// Operations that saturate
APInt sadd_sat(const APInt &RHS) const;
APInt uadd_sat(const APInt &RHS) const;
APInt ssub_sat(const APInt &RHS) const;
APInt usub_sat(const APInt &RHS) const;
APInt smul_sat(const APInt &RHS) const;
APInt umul_sat(const APInt &RHS) const;
APInt sshl_sat(const APInt &RHS) const;
APInt ushl_sat(const APInt &RHS) const;

/// Array-indexing support.
///
/// \returns the bit value at bitPosition
bool operator[](unsigned bitPosition) const {
  assert(bitPosition < getBitWidth() && "Bit position out of bounds!")(static_cast<void> (0));
  return (maskBit(bitPosition) & getWord(bitPosition)) != 0;
}

/// @}
/// \name Comparison Operators
/// @{

/// Equality operator.
///
/// Compares this APInt with RHS for the validity of the equality
/// relationship.
bool operator==(const APInt &RHS) const {
  assert(BitWidth == RHS.BitWidth && "Comparison requires equal bit widths")(static_cast<void> (0));
  if (isSingleWord())
    return U.VAL == RHS.U.VAL;
  return EqualSlowCase(RHS);
}

/// Equality operator.
///
/// Compares this APInt with a uint64_t for the validity of the equality
/// relationship.
///
/// \returns true if *this == Val
bool operator==(uint64_t Val) const {
  return (isSingleWord() || getActiveBits() <= 64) && getZExtValue() == Val;
}

/// Equality comparison.
///
/// Compares this APInt with RHS for the validity of the equality
/// relationship.
///
/// \returns true if *this == Val
bool eq(const APInt &RHS) const { return (*this) == RHS; }

/// Inequality operator.
///
/// Compares this APInt with RHS for the validity of the inequality
/// relationship.
///
/// \returns true if *this != Val
bool operator!=(const APInt &RHS) const { return !((*this) == RHS); }

/// Inequality operator.
///
/// Compares this APInt with a uint64_t for the validity of the inequality
/// relationship.
///
/// \returns true if *this != Val
bool operator!=(uint64_t Val) const { return !((*this) == Val); }

/// Inequality comparison
///
/// Compares this APInt with RHS for the validity of the inequality
/// relationship.
///
/// \returns true if *this != Val
bool ne(const APInt &RHS) const { return !((*this) == RHS); }

/// Unsigned less than comparison
///
/// Regards both *this and RHS as unsigned quantities and compares them for
/// the validity of the less-than relationship.
///
/// \returns true if *this < RHS when both are considered unsigned.
bool ult(const APInt &RHS) const { return compare(RHS) < 0; }

/// Unsigned less than comparison
///
/// Regards both *this as an unsigned quantity and compares it with RHS for
/// the validity of the less-than relationship.
///
/// \returns true if *this < RHS when considered unsigned.
bool ult(uint64_t RHS) const {
  // Only need to check active bits if not a single word.
  return (isSingleWord() || getActiveBits() <= 64) && getZExtValue() < RHS;
}

/// Signed less than comparison
///
/// Regards both *this and RHS as signed quantities and compares them for
/// validity of the less-than relationship.
///
/// \returns true if *this < RHS when both are considered signed.
bool slt(const APInt &RHS) const { return compareSigned(RHS) < 0; }

/// Signed less than comparison
///
/// Regards both *this as a signed quantity and compares it with RHS for
/// the validity of the less-than relationship.
///
/// \returns true if *this < RHS when considered signed.
bool slt(int64_t RHS) const {
  return (!isSingleWord() && getMinSignedBits() > 64) ? isNegative()
                                                      : getSExtValue() < RHS;
}

/// Unsigned less or equal comparison
///
/// Regards both *this and RHS as unsigned quantities and compares them for
/// validity of the less-or-equal relationship.
///
/// \returns true if *this <= RHS when both are considered unsigned.
bool ule(const APInt &RHS) const { return compare(RHS) <= 0; }

/// Unsigned less or equal comparison
///
/// Regards both *this as an unsigned quantity and compares it with RHS for
/// the validity of the less-or-equal relationship.
///
/// \returns true if *this <= RHS when considered unsigned.
bool ule(uint64_t RHS) const { return !ugt(RHS); }

/// Signed less or equal comparison
///
/// Regards both *this and RHS as signed quantities and compares them for
/// validity of the less-or-equal relationship.
///
/// \returns true if *this <= RHS when both are considered signed.
bool sle(const APInt &RHS) const { return compareSigned(RHS) <= 0; }

/// Signed less or equal comparison
///
/// Regards both *this as a signed quantity and compares it with RHS for the
/// validity of the less-or-equal relationship.
///
/// \returns true if *this <= RHS when considered signed.
bool sle(uint64_t RHS) const { return !sgt(RHS); }

/// Unsigned greater than comparison
///
/// Regards both *this and RHS as unsigned quantities and compares them for
/// the validity of the greater-than relationship.
///
/// \returns true if *this > RHS when both are considered unsigned.
bool ugt(const APInt &RHS) const { return !ule(RHS); }

/// Unsigned greater than comparison
///
/// Regards both *this as an unsigned quantity and compares it with RHS for
/// the validity of the greater-than relationship.
///
/// \returns true if *this > RHS when considered unsigned.
bool ugt(uint64_t RHS) const {
  // Only need to check active bits if not a single word.
  return (!isSingleWord() && getActiveBits() > 64) || getZExtValue() > RHS;
}

/// Signed greater than comparison
///
/// Regards both *this and RHS as signed quantities and compares them for the
/// validity of the greater-than relationship.
///
/// \returns true if *this > RHS when both are considered signed.
bool sgt(const APInt &RHS) const { return !sle(RHS); }

/// Signed greater than comparison
///
/// Regards both *this as a signed quantity and compares it with RHS for
/// the validity of the greater-than relationship.
///
/// \returns true if *this > RHS when considered signed.
bool sgt(int64_t RHS) const {
  return (!isSingleWord() && getMinSignedBits() > 64) ? !isNegative()
                                                      : getSExtValue() > RHS;
}

/// Unsigned greater or equal comparison
///
/// Regards both *this and RHS as unsigned quantities and compares them for
/// validity of the greater-or-equal relationship.
///
/// \returns true if *this >= RHS when both are considered unsigned.
bool uge(const APInt &RHS) const { return !ult(RHS); }

/// Unsigned greater or equal comparison
///
/// Regards both *this as an unsigned quantity and compares it with RHS for
/// the validity of the greater-or-equal relationship.
///
/// \returns true if *this >= RHS when considered unsigned.
bool uge(uint64_t RHS) const { return !ult(RHS); }

/// Signed greater or equal comparison
///
/// Regards both *this and RHS as signed quantities and compares them for
/// validity of the greater-or-equal relationship.
///
/// \returns true if *this >= RHS when both are considered signed.
bool sge(const APInt &RHS) const { return !slt(RHS); }

/// Signed greater or equal comparison
///
/// Regards both *this as a signed quantity and compares it with RHS for
/// the validity of the greater-or-equal relationship.
///
/// \returns true if *this >= RHS when considered signed.
bool sge(int64_t RHS) const { return !slt(RHS); }

/// This operation tests if there are any pairs of corresponding bits
/// between this APInt and RHS that are both set.
bool intersects(const APInt &RHS) const {
  assert(BitWidth == RHS.BitWidth && "Bit widths must be the same")(static_cast<void> (0));
  if (isSingleWord())
    return (U.VAL & RHS.U.VAL) != 0;
  return intersectsSlowCase(RHS);
}

/// This operation checks that all bits set in this APInt are also set in RHS.
bool isSubsetOf(const APInt &RHS) const {
  assert(BitWidth == RHS.BitWidth && "Bit widths must be the same")(static_cast<void> (0));
  if (isSingleWord())
    return (U.VAL & ~RHS.U.VAL) == 0;
  return isSubsetOfSlowCase(RHS);
}

/// @}
/// \name Resizing Operators
/// @{

/// Truncate to new width.
///
/// Truncate the APInt to a specified width. It is an error to specify a width
/// that is greater than or equal to the current width.
APInt trunc(unsigned width) const;

/// Truncate to new width with unsigned saturation.
///
/// If the APInt, treated as unsigned integer, can be losslessly truncated to
/// the new bitwidth, then return truncated APInt. Else, return max value.
APInt truncUSat(unsigned width) const;

/// Truncate to new width with signed saturation.
///
/// If this APInt, treated as signed integer, can be losslessly truncated to
/// the new bitwidth, then return truncated APInt. Else, return either
/// signed min value if the APInt was negative, or signed max value.
APInt truncSSat(unsigned width) const;

/// Sign extend to a new width.
///
/// This operation sign extends the APInt to a new width. If the high order
/// bit is set, the fill on the left will be done with 1 bits, otherwise zero.
/// It is an error to specify a width that is less than or equal to the
/// current width.
APInt sext(unsigned width) const;

/// Zero extend to a new width.
///
/// This operation zero extends the APInt to a new width. The high order bits
/// are filled with 0 bits.  It is an error to specify a width that is less
/// than or equal to the current width.
APInt zext(unsigned width) const;

/// Sign extend or truncate to width
///
/// Make this APInt have the bit width given by \p width. The value is sign
/// extended, truncated, or left alone to make it that width.
APInt sextOrTrunc(unsigned width) const;

/// Zero extend or truncate to width
///
/// Make this APInt have the bit width given by \p width. The value is zero
/// extended, truncated, or left alone to make it that width.
APInt zextOrTrunc(unsigned width) const;

/// Truncate to width
///
/// Make this APInt have the bit width given by \p width. The value is
/// truncated or left alone to make it that width.
APInt truncOrSelf(unsigned width) const;

/// Sign extend or truncate to width
///
/// Make this APInt have the bit width given by \p width. The value is sign
/// extended, or left alone to make it that width.
APInt sextOrSelf(unsigned width) const;

/// Zero extend or truncate to width
///
/// Make this APInt have the bit width given by \p width. The value is zero
/// extended, or left alone to make it that width.
APInt zextOrSelf(unsigned width) const;

/// @}
/// \name Bit Manipulation Operators
/// @{

/// Set every bit to 1.
void setAllBits() {
  if (isSingleWord())
    U.VAL = WORDTYPE_MAX;
  else
    // Set all the bits in all the words.
    memset(U.pVal, -1, getNumWords() * APINT_WORD_SIZE);
  // Clear the unused ones
  clearUnusedBits();
}

/// Set a given bit to 1.
///
/// Set the given bit to 1 whose position is given as "bitPosition".
void setBit(unsigned BitPosition) {
  assert(BitPosition < BitWidth && "BitPosition out of range")(static_cast<void> (0));
  WordType Mask = maskBit(BitPosition);
  if (isSingleWord())
    U.VAL |= Mask;
  else
    U.pVal[whichWord(BitPosition)] |= Mask;
}

/// Set the sign bit to 1.
void setSignBit() {
  setBit(BitWidth - 1);
}

/// Set a given bit to a given value.
void setBitVal(unsigned BitPosition, bool BitValue) {
  if (BitValue)
    setBit(BitPosition);
  else
    clearBit(BitPosition);
}

/// Set the bits from loBit (inclusive) to hiBit (exclusive) to 1.
/// This function handles "wrap" case when \p loBit >= \p hiBit, and calls
/// setBits when \p loBit < \p hiBit.
/// For \p loBit == \p hiBit wrap case, set every bit to 1.
void setBitsWithWrap(unsigned loBit, unsigned hiBit) {
  assert(hiBit <= BitWidth && "hiBit out of range")(static_cast<void> (0));
  assert(loBit <= BitWidth && "loBit out of range")(static_cast<void> (0));
  if (loBit < hiBit) {
    setBits(loBit, hiBit);
    return;
  }
  setLowBits(hiBit);
  setHighBits(BitWidth - loBit);
}

/// Set the bits from loBit (inclusive) to hiBit (exclusive) to 1.
/// This function handles case when \p loBit <= \p hiBit.
void setBits(unsigned loBit, unsigned hiBit) {
  assert(hiBit <= BitWidth && "hiBit out of range")(static_cast<void> (0));
  assert(loBit <= BitWidth && "loBit out of range")(static_cast<void> (0));
  assert(loBit <= hiBit && "loBit greater than hiBit")(static_cast<void> (0));
  if (loBit == hiBit)
    return;
  if (loBit < APINT_BITS_PER_WORD && hiBit <= APINT_BITS_PER_WORD) {
    uint64_t mask = WORDTYPE_MAX >> (APINT_BITS_PER_WORD - (hiBit - loBit));
    mask <<= loBit;
    if (isSingleWord())
      U.VAL |= mask;
    else
      U.pVal[0] |= mask;
  } else {
    setBitsSlowCase(loBit, hiBit);
  }
}

/// Set the top bits starting from loBit.
void setBitsFrom(unsigned loBit) {
  return setBits(loBit, BitWidth);
}

/// Set the bottom loBits bits.
void setLowBits(unsigned loBits) {
  return setBits(0, loBits);
}

/// Set the top hiBits bits.
void setHighBits(unsigned hiBits) {
  return setBits(BitWidth - hiBits, BitWidth);
}

/// Set every bit to 0.
void clearAllBits() {
  if (isSingleWord())
    U.VAL = 0;
  else
    memset(U.pVal, 0, getNumWords() * APINT_WORD_SIZE);
}

/// Set a given bit to 0.
///
/// Set the given bit to 0 whose position is given as "bitPosition".
void clearBit(unsigned BitPosition) {
  assert(BitPosition < BitWidth && "BitPosition out of range")(static_cast<void> (0));
  WordType Mask = ~maskBit(BitPosition);
  if (isSingleWord())
    U.VAL &= Mask;
  else
    U.pVal[whichWord(BitPosition)] &= Mask;
}

/// Set bottom loBits bits to 0.
void clearLowBits(unsigned loBits) {
  assert(loBits <= BitWidth && "More bits than bitwidth")(static_cast<void> (0));
  APInt Keep = getHighBitsSet(BitWidth, BitWidth - loBits);
  *this &= Keep;
}

/// Set the sign bit to 0.
void clearSignBit() {
  clearBit(BitWidth - 1);
}

/// Toggle every bit to its opposite value.
void flipAllBits() {
  if (isSingleWord()) {
    U.VAL ^= WORDTYPE_MAX;
    clearUnusedBits();
  } else {
    flipAllBitsSlowCase();
  }
}

/// Toggles a given bit to its opposite value.
///
/// Toggle a given bit to its opposite value whose position is given
/// as "bitPosition".
void flipBit(unsigned bitPosition);

/// Negate this APInt in place.
void negate() {
  flipAllBits();
  ++(*this);
}

/// Insert the bits from a smaller APInt starting at bitPosition.
void insertBits(const APInt &SubBits, unsigned bitPosition);
void insertBits(uint64_t SubBits, unsigned bitPosition, unsigned numBits);

/// Return an APInt with the extracted bits [bitPosition,bitPosition+numBits).
APInt extractBits(unsigned numBits, unsigned bitPosition) const;
uint64_t extractBitsAsZExtValue(unsigned numBits, unsigned bitPosition) const;

/// @}
/// \name Value Characterization Functions
/// @{

/// Return the number of bits in the APInt.
unsigned getBitWidth() const { return BitWidth; }

/// Get the number of words.
///
/// Here one word's bitwidth equals to that of uint64_t.
///
/// \returns the number of words to hold the integer value of this APInt.
unsigned getNumWords() const { return getNumWords(BitWidth); }

/// Get the number of words.
///
/// *NOTE* Here one word's bitwidth equals to that of uint64_t.
///
/// \returns the number of words to hold the integer value with a given bit
/// width.
static unsigned getNumWords(unsigned BitWidth) {
  return ((uint64_t)BitWidth + APINT_BITS_PER_WORD - 1) / APINT_BITS_PER_WORD;
}

/// Compute the number of active bits in the value
///
/// This function returns the number of active bits which is defined as the
/// bit width minus the number of leading zeros. This is used in several
/// computations to see how "wide" the value is.
unsigned getActiveBits() const { return BitWidth - countLeadingZeros(); }

/// Compute the number of active words in the value of this APInt.
///
/// This is used in conjunction with getActiveData to extract the raw value of
/// the APInt.
unsigned getActiveWords() const {
  unsigned numActiveBits = getActiveBits();
  return numActiveBits ? whichWord(numActiveBits - 1) + 1 : 1;
}

/// Get the minimum bit size for this signed APInt
///
/// Computes the minimum bit width for this APInt while considering it to be a
/// signed (and probably negative) value. If the value is not negative, this
/// function returns the same value as getActiveBits()+1. Otherwise, it
/// returns the smallest bit width that will retain the negative value. For
/// example, -1 can be written as 0b1 or 0xFFFFFFFFFF. 0b1 is shorter and so
/// for -1, this function will always return 1.
unsigned getMinSignedBits() const { return BitWidth - getNumSignBits() + 1; }

/// Get zero extended value
///
/// This method attempts to return the value of this APInt as a zero extended
/// uint64_t. The bitwidth must be <= 64 or the value must fit within a
/// uint64_t. Otherwise an assertion will result.
uint64_t getZExtValue() const {
  if (isSingleWord())
    return U.VAL;
  assert(getActiveBits() <= 64 && "Too many bits for uint64_t")(static_cast<void> (0));
  return U.pVal[0];
}

/// Get sign extended value
///
/// This method attempts to return the value of this APInt as a sign extended
/// int64_t. The bit width must be <= 64 or the value must fit within an
/// int64_t. Otherwise an assertion will result.
int64_t getSExtValue() const {
  if (isSingleWord())
    return SignExtend64(U.VAL, BitWidth);
  assert(getMinSignedBits() <= 64 && "Too many bits for int64_t")(static_cast<void> (0));
  return int64_t(U.pVal[0]);
}

/// Get bits required for string value.
///
/// This method determines how many bits are required to hold the APInt
/// equivalent of the string given by \p str.
static unsigned getBitsNeeded(StringRef str, uint8_t radix);

/// The APInt version of the countLeadingZeros functions in
///   MathExtras.h.
///
/// It counts the number of zeros from the most significant bit to the first
/// one bit.
///
/// \returns BitWidth if the value is zero, otherwise returns the number of
///   zeros from the most significant bit to the first one bits.
unsigned countLeadingZeros() const {
  if (isSingleWord()) {
    unsigned unusedBits = APINT_BITS_PER_WORD - BitWidth;
    return llvm::countLeadingZeros(U.VAL) - unusedBits;
  }
  return countLeadingZerosSlowCase();
}

/// Count the number of leading one bits.
///
/// This function is an APInt version of the countLeadingOnes
/// functions in MathExtras.h. It counts the number of ones from the most
/// significant bit to the first zero bit.
///
/// \returns 0 if the high order bit is not set, otherwise returns the number
/// of 1 bits from the most significant to the least
unsigned countLeadingOnes() const {
  if (isSingleWord())
    return llvm::countLeadingOnes(U.VAL << (APINT_BITS_PER_WORD - BitWidth));
  return countLeadingOnesSlowCase();
}

/// Computes the number of leading bits of this APInt that are equal to its
/// sign bit.
unsigned getNumSignBits() const {
  return isNegative() ? countLeadingOnes() : countLeadingZeros();
}

/// Count the number of trailing zero bits.
///
/// This function is an APInt version of the countTrailingZeros
/// functions in MathExtras.h. It counts the number of zeros from the least
/// significant bit to the first set bit.
///
/// \returns BitWidth if the value is zero, otherwise returns the number of
/// zeros from the least significant bit to the first one bit.
unsigned countTrailingZeros() const {
  if (isSingleWord()) {
    unsigned TrailingZeros = llvm::countTrailingZeros(U.VAL);
    return (TrailingZeros > BitWidth ? BitWidth : TrailingZeros);
  }
  return countTrailingZerosSlowCase();
}

/// Count the number of trailing one bits.
///
/// This function is an APInt version of the countTrailingOnes
/// functions in MathExtras.h. It counts the number of ones from the least
/// significant bit to the first zero bit.
///
/// \returns BitWidth if the value is all ones, otherwise returns the number
/// of ones from the least significant bit to the first zero bit.
unsigned countTrailingOnes() const {
  if (isSingleWord())
    return llvm::countTrailingOnes(U.VAL);
  return countTrailingOnesSlowCase();
}

/// Count the number of bits set.
///
/// This function is an APInt version of the countPopulation functions
/// in MathExtras.h. It counts the number of 1 bits in the APInt value.
///
/// \returns 0 if the value is zero, otherwise returns the number of set bits.
unsigned countPopulation() const {
  if (isSingleWord())
    return llvm::countPopulation(U.VAL);
  return countPopulationSlowCase();
}

/// @}
/// \name Conversion Functions
/// @{
void print(raw_ostream &OS, bool isSigned) const;

/// Converts an APInt to a string and append it to Str.  Str is commonly a
/// SmallString.
void toString(SmallVectorImpl<char> &Str, unsigned Radix, bool Signed,
              bool formatAsCLiteral = false) const;

/// Considers the APInt to be unsigned and converts it into a string in the
/// radix given. The radix can be 2, 8, 10 16, or 36.
void toStringUnsigned(SmallVectorImpl<char> &Str, unsigned Radix = 10) const {
  toString(Str, Radix, false, false);
}

/// Considers the APInt to be signed and converts it into a string in the
/// radix given. The radix can be 2, 8, 10, 16, or 36.
void toStringSigned(SmallVectorImpl<char> &Str, unsigned Radix = 10) const {
  toString(Str, Radix, true, false);
}

/// \returns a byte-swapped representation of this APInt Value.
APInt byteSwap() const;

/// \returns the value with the bit representation reversed of this APInt
/// Value.
APInt reverseBits() const;

/// Converts this APInt to a double value.
double roundToDouble(bool isSigned) const;

/// Converts this unsigned APInt to a double value.
double roundToDouble() const { return roundToDouble(false); }

/// Converts this signed APInt to a double value.
double signedRoundToDouble() const { return roundToDouble(true); }

/// Converts APInt bits to a double
///
/// The conversion does not do a translation from integer to double, it just
/// re-interprets the bits as a double. Note that it is valid to do this on
/// any bit width. Exactly 64 bits will be translated.
double bitsToDouble() const {
  return BitsToDouble(getWord(0));
}

/// Converts APInt bits to a float
///
/// The conversion does not do a translation from integer to float, it just
/// re-interprets the bits as a float. Note that it is valid to do this on
/// any bit width. Exactly 32 bits will be translated.
float bitsToFloat() const {
  return BitsToFloat(static_cast<uint32_t>(getWord(0)));
}

/// Converts a double to APInt bits.
///
/// The conversion does not do a translation from double to integer, it just
/// re-interprets the bits of the double.
static APInt doubleToBits(double V) {
  return APInt(sizeof(double) * CHAR_BIT8, DoubleToBits(V));
}

/// Converts a float to APInt bits.
///
/// The conversion does not do a translation from float to integer, it just
/// re-interprets the bits of the float.
static APInt floatToBits(float V) {
  return APInt(sizeof(float) * CHAR_BIT8, FloatToBits(V));
}

/// @}
/// \name Mathematics Operations
/// @{

/// \returns the floor log base 2 of this APInt.
unsigned logBase2() const { return getActiveBits() -  1; }

/// \returns the ceil log base 2 of this APInt.
unsigned ceilLogBase2() const {
  APInt temp(*this);
  --temp;
  return temp.getActiveBits();
}

/// \returns the nearest log base 2 of this APInt. Ties round up.
///
/// NOTE: When we have a BitWidth of 1, we define:
///
///   log2(0) = UINT32_MAX
///   log2(1) = 0
///
/// to get around any mathematical concerns resulting from
/// referencing 2 in a space where 2 does no exist.
unsigned nearestLogBase2() const {
  // Special case when we have a bitwidth of 1. If VAL is 1, then we
  // get 0. If VAL is 0, we get WORDTYPE_MAX which gets truncated to
  // UINT32_MAX.
  if (BitWidth == 1)
    return U.VAL - 1;

  // Handle the zero case.
  if (isNullValue())
    return UINT32_MAX(4294967295U);

  // The non-zero case is handled by computing:
  //
  //   nearestLogBase2(x) = logBase2(x) + x[logBase2(x)-1].
  //
  // where x[i] is referring to the value of the ith bit of x.
  unsigned lg = logBase2();
  return lg + unsigned((*this)[lg - 1]);
}

/// \returns the log base 2 of this APInt if its an exact power of two, -1
/// otherwise
int32_t exactLogBase2() const {
  if (!isPowerOf2())
    return -1;
  return logBase2();
}

/// Compute the square root
APInt sqrt() const;

/// Get the absolute value;
///
/// If *this is < 0 then return -(*this), otherwise *this;
APInt abs() const {
  if (isNegative())
    return -(*this);
  return *this;
}

/// \returns the multiplicative inverse for a given modulo.
APInt multiplicativeInverse(const APInt &modulo) const;

/// @}
/// \name Support for division by constant
/// @{

/// Calculate the magic number for signed division by a constant.
struct ms;
ms magic() const;

/// Calculate the magic number for unsigned division by a constant.
struct mu;
mu magicu(unsigned LeadingZeros = 0) const;

/// @}
/// \name Building-block Operations for APInt and APFloat
/// @{

// These building block operations operate on a representation of arbitrary
// precision, two's-complement, bignum integer values. They should be
// sufficient to implement APInt and APFloat bignum requirements. Inputs are
// generally a pointer to the base of an array of integer parts, representing
// an unsigned bignum, and a count of how many parts there are.

/// Sets the least significant part of a bignum to the input value, and zeroes
/// out higher parts.
static void tcSet(WordType *, WordType, unsigned);

/// Assign one bignum to another.
static void tcAssign(WordType *, const WordType *, unsigned);

/// Returns true if a bignum is zero, false otherwise.
static bool tcIsZero(const WordType *, unsigned);

/// Extract the given bit of a bignum; returns 0 or 1.  Zero-based.
static int tcExtractBit(const WordType *, unsigned bit);

/// Copy the bit vector of width srcBITS from SRC, starting at bit srcLSB, to
/// DST, of dstCOUNT parts, such that the bit srcLSB becomes the least
/// significant bit of DST.  All high bits above srcBITS in DST are
/// zero-filled.
static void tcExtract(WordType *, unsigned dstCount,
                      const WordType *, unsigned srcBits,
                      unsigned srcLSB);

/// Set the given bit of a bignum.  Zero-based.
static void tcSetBit(WordType *, unsigned bit);

/// Clear the given bit of a bignum.  Zero-based.
static void tcClearBit(WordType *, unsigned bit);

/// Returns the bit number of the least or most significant set bit of a
/// number.  If the input number has no bits set -1U is returned.
static unsigned tcLSB(const WordType *, unsigned n);
static unsigned tcMSB(const WordType *parts, unsigned n);

/// Negate a bignum in-place.
static void tcNegate(WordType *, unsigned);

/// DST += RHS + CARRY where CARRY is zero or one.  Returns the carry flag.
static WordType tcAdd(WordType *, const WordType *,
                      WordType carry, unsigned);
/// DST += RHS.  Returns the carry flag.
static WordType tcAddPart(WordType *, WordType, unsigned);

/// DST -= RHS + CARRY where CARRY is zero or one. Returns the carry flag.
static WordType tcSubtract(WordType *, const WordType *,
                           WordType carry, unsigned);
/// DST -= RHS.  Returns the carry flag.
static WordType tcSubtractPart(WordType *, WordType, unsigned);

/// DST += SRC * MULTIPLIER + PART   if add is true
/// DST  = SRC * MULTIPLIER + PART   if add is false
///
/// Requires 0 <= DSTPARTS <= SRCPARTS + 1.  If DST overlaps SRC they must
/// start at the same point, i.e. DST == SRC.
///
/// If DSTPARTS == SRC_PARTS + 1 no overflow occurs and zero is returned.
/// Otherwise DST is filled with the least significant DSTPARTS parts of the
/// result, and if all of the omitted higher parts were zero return zero,
/// otherwise overflow occurred and return one.
static int tcMultiplyPart(WordType *dst, const WordType *src,
                          WordType multiplier, WordType carry,
                          unsigned srcParts, unsigned dstParts,
                          bool add);

/// DST = LHS * RHS, where DST has the same width as the operands and is
/// filled with the least significant parts of the result.  Returns one if
/// overflow occurred, otherwise zero.  DST must be disjoint from both
/// operands.
static int tcMultiply(WordType *, const WordType *, const WordType *,
                      unsigned);

/// DST = LHS * RHS, where DST has width the sum of the widths of the
/// operands. No overflow occurs. DST must be disjoint from both operands.
static void tcFullMultiply(WordType *, const WordType *,
                           const WordType *, unsigned, unsigned);

/// If RHS is zero LHS and REMAINDER are left unchanged, return one.
/// Otherwise set LHS to LHS / RHS with the fractional part discarded, set
/// REMAINDER to the remainder, return zero.  i.e.
///
///  OLD_LHS = RHS * LHS + REMAINDER
///
/// SCRATCH is a bignum of the same size as the operands and result for use by
/// the routine; its contents need not be initialized and are destroyed.  LHS,
/// REMAINDER and SCRATCH must be distinct.
static int tcDivide(WordType *lhs, const WordType *rhs,
                    WordType *remainder, WordType *scratch,
                    unsigned parts);

/// Shift a bignum left Count bits. Shifted in bits are zero. There are no
/// restrictions on Count.
static void tcShiftLeft(WordType *, unsigned Words, unsigned Count);

/// Shift a bignum right Count bits.  Shifted in bits are zero.  There are no
/// restrictions on Count.
static void tcShiftRight(WordType *, unsigned Words, unsigned Count);

/// The obvious AND, OR and XOR and complement operations.
static void tcAnd(WordType *, const WordType *, unsigned);
static void tcOr(WordType *, const WordType *, unsigned);
static void tcXor(WordType *, const WordType *, unsigned);
static void tcComplement(WordType *, unsigned);

/// Comparison (unsigned) of two bignums.
static int tcCompare(const WordType *, const WordType *, unsigned);

/// Increment a bignum in-place.  Return the carry flag.
static WordType tcIncrement(WordType *dst, unsigned parts) {
  return tcAddPart(dst, 1, parts);
}

/// Decrement a bignum in-place.  Return the borrow flag.
static WordType tcDecrement(WordType *dst, unsigned parts) {
  return tcSubtractPart(dst, 1, parts);
}

/// Set the least significant BITS and clear the rest.
static void tcSetLeastSignificantBits(WordType *, unsigned, unsigned bits);

/// debug method
void dump() const;

/// @}
2015};

2017/// Magic data for optimising signed division by a constant.
2018struct APInt::ms {
APInt m;    ///< magic number
unsigned s; ///< shift amount
2021};

2023/// Magic data for optimising unsigned division by a constant.
2024struct APInt::mu {
APInt m;    ///< magic number
bool a;     ///< add indicator
unsigned s; ///< shift amount
2028};

2030inline bool operator==(uint64_t V1, const APInt &V2) { return V2 == V1; }

2032inline bool operator!=(uint64_t V1, const APInt &V2) { return V2 != V1; }

2034/// Unary bitwise complement operator.
2035///
2036/// \returns an APInt that is the bitwise complement of \p v.
2037inline APInt operator~(APInt v) {
v.flipAllBits();
return v;
2040}

2042inline APInt operator&(APInt a, const APInt &b) {
a &= b;
return a;
2045}

2047inline APInt operator&(const APInt &a, APInt &&b) {
b &= a;
return std::move(b);
2050}

2052inline APInt operator&(APInt a, uint64_t RHS) {
a &= RHS;
return a;
2055}

2057inline APInt operator&(uint64_t LHS, APInt b) {
b &= LHS;
return b;
2060}

2062inline APInt operator|(APInt a, const APInt &b) {
a |= b;
return a;
2065}

2067inline APInt operator|(const APInt &a, APInt &&b) {
b |= a;
return std::move(b);
2070}

2072inline APInt operator|(APInt a, uint64_t RHS) {
a |= RHS;
return a;
2075}

2077inline APInt operator|(uint64_t LHS, APInt b) {
b |= LHS;
return b;
2080}

2082inline APInt operator^(APInt a, const APInt &b) {
a ^= b;
return a;
2085}

2087inline APInt operator^(const APInt &a, APInt &&b) {
b ^= a;
return std::move(b);
2090}

2092inline APInt operator^(APInt a, uint64_t RHS) {
a ^= RHS;
return a;
2095}

2097inline APInt operator^(uint64_t LHS, APInt b) {
b ^= LHS;
return b;
2100}

2102inline raw_ostream &operator<<(raw_ostream &OS, const APInt &I) {
I.print(OS, true);
return OS;
2105}

2107inline APInt operator-(APInt v) {
v.negate();
return v;
2110}

2112inline APInt operator+(APInt a, const APInt &b) {
a += b;
return a;
2115}

2117inline APInt operator+(const APInt &a, APInt &&b) {
b += a;
return std::move(b);
2120}

2122inline APInt operator+(APInt a, uint64_t RHS) {
a += RHS;
return a;
2125}

2127inline APInt operator+(uint64_t LHS, APInt b) {
b += LHS;
return b;
2130}

2132inline APInt operator-(APInt a, const APInt &b) {
a -= b;
return a;
2135}

2137inline APInt operator-(const APInt &a, APInt &&b) {
b.negate();
b += a;
return std::move(b);
2141}

2143inline APInt operator-(APInt a, uint64_t RHS) {
a -= RHS;
return a;
2146}

2148inline APInt operator-(uint64_t LHS, APInt b) {
b.negate();
b += LHS;
return b;
2152}

2154inline APInt operator*(APInt a, uint64_t RHS) {
a *= RHS;
return a;
2157}

2159inline APInt operator*(uint64_t LHS, APInt b) {
b *= LHS;
return b;
2162}


2165namespace APIntOps {

2167/// Determine the smaller of two APInts considered to be signed.
2168inline const APInt &smin(const APInt &A, const APInt &B) {
return A.slt(B) ? A : B;
2170}

2172/// Determine the larger of two APInts considered to be signed.
2173inline const APInt &smax(const APInt &A, const APInt &B) {
return A.sgt(B) ? A : B;
2175}

2177/// Determine the smaller of two APInts considered to be unsigned.
2178inline const APInt &umin(const APInt &A, const APInt &B) {
return A.ult(B) ? A : B;
2180}

2182/// Determine the larger of two APInts considered to be unsigned.
2183inline const APInt &umax(const APInt &A, const APInt &B) {
return A.ugt(B) ? A : B;
2185}

2187/// Compute GCD of two unsigned APInt values.
2188///
2189/// This function returns the greatest common divisor of the two APInt values
2190/// using Stein's algorithm.
2191///
2192/// \returns the greatest common divisor of A and B.
2193APInt GreatestCommonDivisor(APInt A, APInt B);

2195/// Converts the given APInt to a double value.
2196///
2197/// Treats the APInt as an unsigned value for conversion purposes.
2198inline double RoundAPIntToDouble(const APInt &APIVal) {
return APIVal.roundToDouble();
2200}

2202/// Converts the given APInt to a double value.
2203///
2204/// Treats the APInt as a signed value for conversion purposes.
2205inline double RoundSignedAPIntToDouble(const APInt &APIVal) {
return APIVal.signedRoundToDouble();
2207}

2209/// Converts the given APInt to a float value.
2210inline float RoundAPIntToFloat(const APInt &APIVal) {
return float(RoundAPIntToDouble(APIVal));
2212}

2214/// Converts the given APInt to a float value.
2215///
2216/// Treats the APInt as a signed value for conversion purposes.
2217inline float RoundSignedAPIntToFloat(const APInt &APIVal) {
return float(APIVal.signedRoundToDouble());
2219}

2221/// Converts the given double value into a APInt.
2222///
2223/// This function convert a double value to an APInt value.
2224APInt RoundDoubleToAPInt(double Double, unsigned width);

2226/// Converts a float value into a APInt.
2227///
2228/// Converts a float value into an APInt value.
2229inline APInt RoundFloatToAPInt(float Float, unsigned width) {
return RoundDoubleToAPInt(double(Float), width);
2231}

2233/// Return A unsign-divided by B, rounded by the given rounding mode.
2234APInt RoundingUDiv(const APInt &A, const APInt &B, APInt::Rounding RM);

2236/// Return A sign-divided by B, rounded by the given rounding mode.
2237APInt RoundingSDiv(const APInt &A, const APInt &B, APInt::Rounding RM);

2239/// Let q(n) = An^2 + Bn + C, and BW = bit width of the value range
2240/// (e.g. 32 for i32).
2241/// This function finds the smallest number n, such that
2242/// (a) n >= 0 and q(n) = 0, or
2243/// (b) n >= 1 and q(n-1) and q(n), when evaluated in the set of all
2244///     integers, belong to two different intervals [Rk, Rk+R),
2245///     where R = 2^BW, and k is an integer.
2246/// The idea here is to find when q(n) "overflows" 2^BW, while at the
2247/// same time "allowing" subtraction. In unsigned modulo arithmetic a
2248/// subtraction (treated as addition of negated numbers) would always
2249/// count as an overflow, but here we want to allow values to decrease
2250/// and increase as long as they are within the same interval.
2251/// Specifically, adding of two negative numbers should not cause an
2252/// overflow (as long as the magnitude does not exceed the bit width).
2253/// On the other hand, given a positive number, adding a negative
2254/// number to it can give a negative result, which would cause the
2255/// value to go from [-2^BW, 0) to [0, 2^BW). In that sense, zero is
2256/// treated as a special case of an overflow.
2257///
2258/// This function returns None if after finding k that minimizes the
2259/// positive solution to q(n) = kR, both solutions are contained between
2260/// two consecutive integers.
2261///
2262/// There are cases where q(n) > T, and q(n+1) < T (assuming evaluation
2263/// in arithmetic modulo 2^BW, and treating the values as signed) by the
2264/// virtue of *signed* overflow. This function will *not* find such an n,
2265/// however it may find a value of n satisfying the inequalities due to
2266/// an *unsigned* overflow (if the values are treated as unsigned).
2267/// To find a solution for a signed overflow, treat it as a problem of
2268/// finding an unsigned overflow with a range with of BW-1.
2269///
2270/// The returned value may have a different bit width from the input
2271/// coefficients.
2272Optional<APInt> SolveQuadraticEquationWrap(APInt A, APInt B, APInt C,
                                         unsigned RangeWidth);

2275/// Compare two values, and if they are different, return the position of the
2276/// most significant bit that is different in the values.
2277Optional<unsigned> GetMostSignificantDifferentBit(const APInt &A,
                                                const APInt &B);

2280} // End of APIntOps namespace

2282// See friend declaration above. This additional declaration is required in
2283// order to compile LLVM with IBM xlC compiler.
2284hash_code hash_value(const APInt &Arg);

2286/// StoreIntToMemory - Fills the StoreBytes bytes of memory starting from Dst
2287/// with the integer held in IntVal.
2288void StoreIntToMemory(const APInt &IntVal, uint8_t *Dst, unsigned StoreBytes);

2290/// LoadIntFromMemory - Loads the integer stored in the LoadBytes bytes starting
2291/// from Src into IntVal, which is assumed to be wide enough and to hold zero.
2292void LoadIntFromMemory(APInt &IntVal, const uint8_t *Src, unsigned LoadBytes);

2294/// Provide DenseMapInfo for APInt.
2295template <> struct DenseMapInfo<APInt> {
static inline APInt getEmptyKey() {
  APInt V(nullptr, 0);
  V.U.VAL = 0;
  return V;
}

static inline APInt getTombstoneKey() {
  APInt V(nullptr, 0);
  V.U.VAL = 1;
  return V;
}

static unsigned getHashValue(const APInt &Key);

static bool isEqual(const APInt &LHS, const APInt &RHS) {
  return LHS.getBitWidth() == RHS.getBitWidth() && LHS == RHS;
}
2313};

2315} // namespace llvm

2317#endif