Remove LLVM 8.0.1 files.

1 files changed, 0 insertions, 5554 deletions

diff --git a/gnu/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/gnu/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
deleted file mode 100644
index b5bbb09935e..00000000000
--- a/gnu/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ /dev/null
@@ -1,5554 +0,0 @@
-//===- InstCombineCompares.cpp --------------------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file implements the visitICmp and visitFCmp functions.
-//
-//===----------------------------------------------------------------------===//
-
-#include "InstCombineInternal.h"
-#include "llvm/ADT/APSInt.h"
-#include "llvm/ADT/SetVector.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/ConstantFolding.h"
-#include "llvm/Analysis/InstructionSimplify.h"
-#include "llvm/Analysis/TargetLibraryInfo.h"
-#include "llvm/IR/ConstantRange.h"
-#include "llvm/IR/DataLayout.h"
-#include "llvm/IR/GetElementPtrTypeIterator.h"
-#include "llvm/IR/IntrinsicInst.h"
-#include "llvm/IR/PatternMatch.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/KnownBits.h"
-
-using namespace llvm;
-using namespace PatternMatch;
-
-#define DEBUG_TYPE "instcombine"
-
-// How many times is a select replaced by one of its operands?
-STATISTIC(NumSel, "Number of select opts");
-
-
-/// Compute Result = In1+In2, returning true if the result overflowed for this
-/// type.
-static bool addWithOverflow(APInt &Result, const APInt &In1,
-                            const APInt &In2, bool IsSigned = false) {
-  bool Overflow;
-  if (IsSigned)
-    Result = In1.sadd_ov(In2, Overflow);
-  else
-    Result = In1.uadd_ov(In2, Overflow);
-
-  return Overflow;
-}
-
-/// Compute Result = In1-In2, returning true if the result overflowed for this
-/// type.
-static bool subWithOverflow(APInt &Result, const APInt &In1,
-                            const APInt &In2, bool IsSigned = false) {
-  bool Overflow;
-  if (IsSigned)
-    Result = In1.ssub_ov(In2, Overflow);
-  else
-    Result = In1.usub_ov(In2, Overflow);
-
-  return Overflow;
-}
-
-/// Given an icmp instruction, return true if any use of this comparison is a
-/// branch on sign bit comparison.
-static bool hasBranchUse(ICmpInst &I) {
-  for (auto *U : I.users())
-    if (isa<BranchInst>(U))
-      return true;
-  return false;
-}
-
-/// Given an exploded icmp instruction, return true if the comparison only
-/// checks the sign bit. If it only checks the sign bit, set TrueIfSigned if the
-/// result of the comparison is true when the input value is signed.
-static bool isSignBitCheck(ICmpInst::Predicate Pred, const APInt &RHS,
-                           bool &TrueIfSigned) {
-  switch (Pred) {
-  case ICmpInst::ICMP_SLT:   // True if LHS s< 0
-    TrueIfSigned = true;
-    return RHS.isNullValue();
-  case ICmpInst::ICMP_SLE:   // True if LHS s<= RHS and RHS == -1
-    TrueIfSigned = true;
-    return RHS.isAllOnesValue();
-  case ICmpInst::ICMP_SGT:   // True if LHS s> -1
-    TrueIfSigned = false;
-    return RHS.isAllOnesValue();
-  case ICmpInst::ICMP_UGT:
-    // True if LHS u> RHS and RHS == high-bit-mask - 1
-    TrueIfSigned = true;
-    return RHS.isMaxSignedValue();
-  case ICmpInst::ICMP_UGE:
-    // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
-    TrueIfSigned = true;
-    return RHS.isSignMask();
-  default:
-    return false;
-  }
-}
-
-/// Returns true if the exploded icmp can be expressed as a signed comparison
-/// to zero and updates the predicate accordingly.
-/// The signedness of the comparison is preserved.
-/// TODO: Refactor with decomposeBitTestICmp()?
-static bool isSignTest(ICmpInst::Predicate &Pred, const APInt &C) {
-  if (!ICmpInst::isSigned(Pred))
-    return false;
-
-  if (C.isNullValue())
-    return ICmpInst::isRelational(Pred);
-
-  if (C.isOneValue()) {
-    if (Pred == ICmpInst::ICMP_SLT) {
-      Pred = ICmpInst::ICMP_SLE;
-      return true;
-    }
-  } else if (C.isAllOnesValue()) {
-    if (Pred == ICmpInst::ICMP_SGT) {
-      Pred = ICmpInst::ICMP_SGE;
-      return true;
-    }
-  }
-
-  return false;
-}
-
-/// Given a signed integer type and a set of known zero and one bits, compute
-/// the maximum and minimum values that could have the specified known zero and
-/// known one bits, returning them in Min/Max.
-/// TODO: Move to method on KnownBits struct?
-static void computeSignedMinMaxValuesFromKnownBits(const KnownBits &Known,
-                                                   APInt &Min, APInt &Max) {
-  assert(Known.getBitWidth() == Min.getBitWidth() &&
-         Known.getBitWidth() == Max.getBitWidth() &&
-         "KnownZero, KnownOne and Min, Max must have equal bitwidth.");
-  APInt UnknownBits = ~(Known.Zero|Known.One);
-
-  // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
-  // bit if it is unknown.
-  Min = Known.One;
-  Max = Known.One|UnknownBits;
-
-  if (UnknownBits.isNegative()) { // Sign bit is unknown
-    Min.setSignBit();
-    Max.clearSignBit();
-  }
-}
-
-/// Given an unsigned integer type and a set of known zero and one bits, compute
-/// the maximum and minimum values that could have the specified known zero and
-/// known one bits, returning them in Min/Max.
-/// TODO: Move to method on KnownBits struct?
-static void computeUnsignedMinMaxValuesFromKnownBits(const KnownBits &Known,
-                                                     APInt &Min, APInt &Max) {
-  assert(Known.getBitWidth() == Min.getBitWidth() &&
-         Known.getBitWidth() == Max.getBitWidth() &&
-         "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
-  APInt UnknownBits = ~(Known.Zero|Known.One);
-
-  // The minimum value is when the unknown bits are all zeros.
-  Min = Known.One;
-  // The maximum value is when the unknown bits are all ones.
-  Max = Known.One|UnknownBits;
-}
-
-/// This is called when we see this pattern:
-///   cmp pred (load (gep GV, ...)), cmpcst
-/// where GV is a global variable with a constant initializer. Try to simplify
-/// this into some simple computation that does not need the load. For example
-/// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3".
-///
-/// If AndCst is non-null, then the loaded value is masked with that constant
-/// before doing the comparison. This handles cases like "A[i]&4 == 0".
-Instruction *InstCombiner::foldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
-                                                        GlobalVariable *GV,
-                                                        CmpInst &ICI,
-                                                        ConstantInt *AndCst) {
-  Constant *Init = GV->getInitializer();
-  if (!isa<ConstantArray>(Init) && !isa<ConstantDataArray>(Init))
-    return nullptr;
-
-  uint64_t ArrayElementCount = Init->getType()->getArrayNumElements();
-  // Don't blow up on huge arrays.
-  if (ArrayElementCount > MaxArraySizeForCombine)
-    return nullptr;
-
-  // There are many forms of this optimization we can handle, for now, just do
-  // the simple index into a single-dimensional array.
-  //
-  // Require: GEP GV, 0, i {{, constant indices}}
-  if (GEP->getNumOperands() < 3 ||
-      !isa<ConstantInt>(GEP->getOperand(1)) ||
-      !cast<ConstantInt>(GEP->getOperand(1))->isZero() ||
-      isa<Constant>(GEP->getOperand(2)))
-    return nullptr;
-
-  // Check that indices after the variable are constants and in-range for the
-  // type they index.  Collect the indices.  This is typically for arrays of
-  // structs.
-  SmallVector<unsigned, 4> LaterIndices;
-
-  Type *EltTy = Init->getType()->getArrayElementType();
-  for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) {
-    ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i));
-    if (!Idx) return nullptr;  // Variable index.
-
-    uint64_t IdxVal = Idx->getZExtValue();
-    if ((unsigned)IdxVal != IdxVal) return nullptr; // Too large array index.
-
-    if (StructType *STy = dyn_cast<StructType>(EltTy))
-      EltTy = STy->getElementType(IdxVal);
-    else if (ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) {
-      if (IdxVal >= ATy->getNumElements()) return nullptr;
-      EltTy = ATy->getElementType();
-    } else {
-      return nullptr; // Unknown type.
-    }
-
-    LaterIndices.push_back(IdxVal);
-  }
-
-  enum { Overdefined = -3, Undefined = -2 };
-
-  // Variables for our state machines.
-
-  // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form
-  // "i == 47 | i == 87", where 47 is the first index the condition is true for,
-  // and 87 is the second (and last) index.  FirstTrueElement is -2 when
-  // undefined, otherwise set to the first true element.  SecondTrueElement is
-  // -2 when undefined, -3 when overdefined and >= 0 when that index is true.
-  int FirstTrueElement = Undefined, SecondTrueElement = Undefined;
-
-  // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the
-  // form "i != 47 & i != 87".  Same state transitions as for true elements.
-  int FirstFalseElement = Undefined, SecondFalseElement = Undefined;
-
-  /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these
-  /// define a state machine that triggers for ranges of values that the index
-  /// is true or false for.  This triggers on things like "abbbbc"[i] == 'b'.
-  /// This is -2 when undefined, -3 when overdefined, and otherwise the last
-  /// index in the range (inclusive).  We use -2 for undefined here because we
-  /// use relative comparisons and don't want 0-1 to match -1.
-  int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined;
-
-  // MagicBitvector - This is a magic bitvector where we set a bit if the
-  // comparison is true for element 'i'.  If there are 64 elements or less in
-  // the array, this will fully represent all the comparison results.
-  uint64_t MagicBitvector = 0;
-
-  // Scan the array and see if one of our patterns matches.
-  Constant *CompareRHS = cast<Constant>(ICI.getOperand(1));
-  for (unsigned i = 0, e = ArrayElementCount; i != e; ++i) {
-    Constant *Elt = Init->getAggregateElement(i);
-    if (!Elt) return nullptr;
-
-    // If this is indexing an array of structures, get the structure element.
-    if (!LaterIndices.empty())
-      Elt = ConstantExpr::getExtractValue(Elt, LaterIndices);
-
-    // If the element is masked, handle it.
-    if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst);
-
-    // Find out if the comparison would be true or false for the i'th element.
-    Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt,
-                                                  CompareRHS, DL, &TLI);
-    // If the result is undef for this element, ignore it.
-    if (isa<UndefValue>(C)) {
-      // Extend range state machines to cover this element in case there is an
-      // undef in the middle of the range.
-      if (TrueRangeEnd == (int)i-1)
-        TrueRangeEnd = i;
-      if (FalseRangeEnd == (int)i-1)
-        FalseRangeEnd = i;
-      continue;
-    }
-
-    // If we can't compute the result for any of the elements, we have to give
-    // up evaluating the entire conditional.
-    if (!isa<ConstantInt>(C)) return nullptr;
-
-    // Otherwise, we know if the comparison is true or false for this element,
-    // update our state machines.
-    bool IsTrueForElt = !cast<ConstantInt>(C)->isZero();
-
-    // State machine for single/double/range index comparison.
-    if (IsTrueForElt) {
-      // Update the TrueElement state machine.
-      if (FirstTrueElement == Undefined)
-        FirstTrueElement = TrueRangeEnd = i;  // First true element.
-      else {
-        // Update double-compare state machine.
-        if (SecondTrueElement == Undefined)
-          SecondTrueElement = i;
-        else
-          SecondTrueElement = Overdefined;
-
-        // Update range state machine.
-        if (TrueRangeEnd == (int)i-1)
-          TrueRangeEnd = i;
-        else
-          TrueRangeEnd = Overdefined;
-      }
-    } else {
-      // Update the FalseElement state machine.
-      if (FirstFalseElement == Undefined)
-        FirstFalseElement = FalseRangeEnd = i; // First false element.
-      else {
-        // Update double-compare state machine.
-        if (SecondFalseElement == Undefined)
-          SecondFalseElement = i;
-        else
-          SecondFalseElement = Overdefined;
-
-        // Update range state machine.
-        if (FalseRangeEnd == (int)i-1)
-          FalseRangeEnd = i;
-        else
-          FalseRangeEnd = Overdefined;
-      }
-    }
-
-    // If this element is in range, update our magic bitvector.
-    if (i < 64 && IsTrueForElt)
-      MagicBitvector |= 1ULL << i;
-
-    // If all of our states become overdefined, bail out early.  Since the
-    // predicate is expensive, only check it every 8 elements.  This is only
-    // really useful for really huge arrays.
-    if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined &&
-        SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined &&
-        FalseRangeEnd == Overdefined)
-      return nullptr;
-  }
-
-  // Now that we've scanned the entire array, emit our new comparison(s).  We
-  // order the state machines in complexity of the generated code.
-  Value *Idx = GEP->getOperand(2);
-
-  // If the index is larger than the pointer size of the target, truncate the
-  // index down like the GEP would do implicitly.  We don't have to do this for
-  // an inbounds GEP because the index can't be out of range.
-  if (!GEP->isInBounds()) {
-    Type *IntPtrTy = DL.getIntPtrType(GEP->getType());
-    unsigned PtrSize = IntPtrTy->getIntegerBitWidth();
-    if (Idx->getType()->getPrimitiveSizeInBits() > PtrSize)
-      Idx = Builder.CreateTrunc(Idx, IntPtrTy);
-  }
-
-  // If the comparison is only true for one or two elements, emit direct
-  // comparisons.
-  if (SecondTrueElement != Overdefined) {
-    // None true -> false.
-    if (FirstTrueElement == Undefined)
-      return replaceInstUsesWith(ICI, Builder.getFalse());
-
-    Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement);
-
-    // True for one element -> 'i == 47'.
-    if (SecondTrueElement == Undefined)
-      return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx);
-
-    // True for two elements -> 'i == 47 | i == 72'.
-    Value *C1 = Builder.CreateICmpEQ(Idx, FirstTrueIdx);
-    Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement);
-    Value *C2 = Builder.CreateICmpEQ(Idx, SecondTrueIdx);
-    return BinaryOperator::CreateOr(C1, C2);
-  }
-
-  // If the comparison is only false for one or two elements, emit direct
-  // comparisons.
-  if (SecondFalseElement != Overdefined) {
-    // None false -> true.
-    if (FirstFalseElement == Undefined)
-      return replaceInstUsesWith(ICI, Builder.getTrue());
-
-    Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement);
-
-    // False for one element -> 'i != 47'.
-    if (SecondFalseElement == Undefined)
-      return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx);
-
-    // False for two elements -> 'i != 47 & i != 72'.
-    Value *C1 = Builder.CreateICmpNE(Idx, FirstFalseIdx);
-    Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement);
-    Value *C2 = Builder.CreateICmpNE(Idx, SecondFalseIdx);
-    return BinaryOperator::CreateAnd(C1, C2);
-  }
-
-  // If the comparison can be replaced with a range comparison for the elements
-  // where it is true, emit the range check.
-  if (TrueRangeEnd != Overdefined) {
-    assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare");
-
-    // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1).
-    if (FirstTrueElement) {
-      Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement);
-      Idx = Builder.CreateAdd(Idx, Offs);
-    }
-
-    Value *End = ConstantInt::get(Idx->getType(),
-                                  TrueRangeEnd-FirstTrueElement+1);
-    return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End);
-  }
-
-  // False range check.
-  if (FalseRangeEnd != Overdefined) {
-    assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare");
-    // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse).
-    if (FirstFalseElement) {
-      Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement);
-      Idx = Builder.CreateAdd(Idx, Offs);
-    }
-
-    Value *End = ConstantInt::get(Idx->getType(),
-                                  FalseRangeEnd-FirstFalseElement);
-    return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End);
-  }
-
-  // If a magic bitvector captures the entire comparison state
-  // of this load, replace it with computation that does:
-  //   ((magic_cst >> i) & 1) != 0
-  {
-    Type *Ty = nullptr;
-
-    // Look for an appropriate type:
-    // - The type of Idx if the magic fits
-    // - The smallest fitting legal type
-    if (ArrayElementCount <= Idx->getType()->getIntegerBitWidth())
-      Ty = Idx->getType();
-    else
-      Ty = DL.getSmallestLegalIntType(Init->getContext(), ArrayElementCount);
-
-    if (Ty) {
-      Value *V = Builder.CreateIntCast(Idx, Ty, false);
-      V = Builder.CreateLShr(ConstantInt::get(Ty, MagicBitvector), V);
-      V = Builder.CreateAnd(ConstantInt::get(Ty, 1), V);
-      return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0));
-    }
-  }
-
-  return nullptr;
-}
-
-/// Return a value that can be used to compare the *offset* implied by a GEP to
-/// zero. For example, if we have &A[i], we want to return 'i' for
-/// "icmp ne i, 0". Note that, in general, indices can be complex, and scales
-/// are involved. The above expression would also be legal to codegen as
-/// "icmp ne (i*4), 0" (assuming A is a pointer to i32).
-/// This latter form is less amenable to optimization though, and we are allowed
-/// to generate the first by knowing that pointer arithmetic doesn't overflow.
-///
-/// If we can't emit an optimized form for this expression, this returns null.
-///
-static Value *evaluateGEPOffsetExpression(User *GEP, InstCombiner &IC,
-                                          const DataLayout &DL) {
-  gep_type_iterator GTI = gep_type_begin(GEP);
-
-  // Check to see if this gep only has a single variable index.  If so, and if
-  // any constant indices are a multiple of its scale, then we can compute this
-  // in terms of the scale of the variable index.  For example, if the GEP
-  // implies an offset of "12 + i*4", then we can codegen this as "3 + i",
-  // because the expression will cross zero at the same point.
-  unsigned i, e = GEP->getNumOperands();
-  int64_t Offset = 0;
-  for (i = 1; i != e; ++i, ++GTI) {
-    if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
-      // Compute the aggregate offset of constant indices.
-      if (CI->isZero()) continue;
-
-      // Handle a struct index, which adds its field offset to the pointer.
-      if (StructType *STy = GTI.getStructTypeOrNull()) {
-        Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
-      } else {
-        uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
-        Offset += Size*CI->getSExtValue();
-      }
-    } else {
-      // Found our variable index.
-      break;
-    }
-  }
-
-  // If there are no variable indices, we must have a constant offset, just
-  // evaluate it the general way.
-  if (i == e) return nullptr;
-
-  Value *VariableIdx = GEP->getOperand(i);
-  // Determine the scale factor of the variable element.  For example, this is
-  // 4 if the variable index is into an array of i32.
-  uint64_t VariableScale = DL.getTypeAllocSize(GTI.getIndexedType());
-
-  // Verify that there are no other variable indices.  If so, emit the hard way.
-  for (++i, ++GTI; i != e; ++i, ++GTI) {
-    ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
-    if (!CI) return nullptr;
-
-    // Compute the aggregate offset of constant indices.
-    if (CI->isZero()) continue;
-
-    // Handle a struct index, which adds its field offset to the pointer.
-    if (StructType *STy = GTI.getStructTypeOrNull()) {
-      Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
-    } else {
-      uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
-      Offset += Size*CI->getSExtValue();
-    }
-  }
-
-  // Okay, we know we have a single variable index, which must be a
-  // pointer/array/vector index.  If there is no offset, life is simple, return
-  // the index.
-  Type *IntPtrTy = DL.getIntPtrType(GEP->getOperand(0)->getType());
-  unsigned IntPtrWidth = IntPtrTy->getIntegerBitWidth();
-  if (Offset == 0) {
-    // Cast to intptrty in case a truncation occurs.  If an extension is needed,
-    // we don't need to bother extending: the extension won't affect where the
-    // computation crosses zero.
-    if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) {
-      VariableIdx = IC.Builder.CreateTrunc(VariableIdx, IntPtrTy);
-    }
-    return VariableIdx;
-  }
-
-  // Otherwise, there is an index.  The computation we will do will be modulo
-  // the pointer size.
-  Offset = SignExtend64(Offset, IntPtrWidth);
-  VariableScale = SignExtend64(VariableScale, IntPtrWidth);
-
-  // To do this transformation, any constant index must be a multiple of the
-  // variable scale factor.  For example, we can evaluate "12 + 4*i" as "3 + i",
-  // but we can't evaluate "10 + 3*i" in terms of i.  Check that the offset is a
-  // multiple of the variable scale.
-  int64_t NewOffs = Offset / (int64_t)VariableScale;
-  if (Offset != NewOffs*(int64_t)VariableScale)
-    return nullptr;
-
-  // Okay, we can do this evaluation.  Start by converting the index to intptr.
-  if (VariableIdx->getType() != IntPtrTy)
-    VariableIdx = IC.Builder.CreateIntCast(VariableIdx, IntPtrTy,
-                                            true /*Signed*/);
-  Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
-  return IC.Builder.CreateAdd(VariableIdx, OffsetVal, "offset");
-}
-
-/// Returns true if we can rewrite Start as a GEP with pointer Base
-/// and some integer offset. The nodes that need to be re-written
-/// for this transformation will be added to Explored.
-static bool canRewriteGEPAsOffset(Value *Start, Value *Base,
-                                  const DataLayout &DL,
-                                  SetVector<Value *> &Explored) {
-  SmallVector<Value *, 16> WorkList(1, Start);
-  Explored.insert(Base);
-
-  // The following traversal gives us an order which can be used
-  // when doing the final transformation. Since in the final
-  // transformation we create the PHI replacement instructions first,
-  // we don't have to get them in any particular order.
-  //
-  // However, for other instructions we will have to traverse the
-  // operands of an instruction first, which means that we have to
-  // do a post-order traversal.
-  while (!WorkList.empty()) {
-    SetVector<PHINode *> PHIs;
-
-    while (!WorkList.empty()) {
-      if (Explored.size() >= 100)
-        return false;
-
-      Value *V = WorkList.back();
-
-      if (Explored.count(V) != 0) {
-        WorkList.pop_back();
-        continue;
-      }
-
-      if (!isa<IntToPtrInst>(V) && !isa<PtrToIntInst>(V) &&
-          !isa<GetElementPtrInst>(V) && !isa<PHINode>(V))
-        // We've found some value that we can't explore which is different from
-        // the base. Therefore we can't do this transformation.
-        return false;
-
-      if (isa<IntToPtrInst>(V) || isa<PtrToIntInst>(V)) {
-        auto *CI = dyn_cast<CastInst>(V);
-        if (!CI->isNoopCast(DL))
-          return false;
-
-        if (Explored.count(CI->getOperand(0)) == 0)
-          WorkList.push_back(CI->getOperand(0));
-      }
-
-      if (auto *GEP = dyn_cast<GEPOperator>(V)) {
-        // We're limiting the GEP to having one index. This will preserve
-        // the original pointer type. We could handle more cases in the
-        // future.
-        if (GEP->getNumIndices() != 1 || !GEP->isInBounds() ||
-            GEP->getType() != Start->getType())
-          return false;
-
-        if (Explored.count(GEP->getOperand(0)) == 0)
-          WorkList.push_back(GEP->getOperand(0));
-      }
-
-      if (WorkList.back() == V) {
-        WorkList.pop_back();
-        // We've finished visiting this node, mark it as such.
-        Explored.insert(V);
-      }
-
-      if (auto *PN = dyn_cast<PHINode>(V)) {
-        // We cannot transform PHIs on unsplittable basic blocks.
-        if (isa<CatchSwitchInst>(PN->getParent()->getTerminator()))
-          return false;
-        Explored.insert(PN);
-        PHIs.insert(PN);
-      }
-    }
-
-    // Explore the PHI nodes further.
-    for (auto *PN : PHIs)
-      for (Value *Op : PN->incoming_values())
-        if (Explored.count(Op) == 0)
-          WorkList.push_back(Op);
-  }
-
-  // Make sure that we can do this. Since we can't insert GEPs in a basic
-  // block before a PHI node, we can't easily do this transformation if
-  // we have PHI node users of transformed instructions.
-  for (Value *Val : Explored) {
-    for (Value *Use : Val->uses()) {
-
-      auto *PHI = dyn_cast<PHINode>(Use);
-      auto *Inst = dyn_cast<Instruction>(Val);
-
-      if (Inst == Base || Inst == PHI || !Inst || !PHI ||
-          Explored.count(PHI) == 0)
-        continue;
-
-      if (PHI->getParent() == Inst->getParent())
-        return false;
-    }
-  }
-  return true;
-}
-
-// Sets the appropriate insert point on Builder where we can add
-// a replacement Instruction for V (if that is possible).
-static void setInsertionPoint(IRBuilder<> &Builder, Value *V,
-                              bool Before = true) {
-  if (auto *PHI = dyn_cast<PHINode>(V)) {
-    Builder.SetInsertPoint(&*PHI->getParent()->getFirstInsertionPt());
-    return;
-  }
-  if (auto *I = dyn_cast<Instruction>(V)) {
-    if (!Before)
-      I = &*std::next(I->getIterator());
-    Builder.SetInsertPoint(I);
-    return;
-  }
-  if (auto *A = dyn_cast<Argument>(V)) {
-    // Set the insertion point in the entry block.
-    BasicBlock &Entry = A->getParent()->getEntryBlock();
-    Builder.SetInsertPoint(&*Entry.getFirstInsertionPt());
-    return;
-  }
-  // Otherwise, this is a constant and we don't need to set a new
-  // insertion point.
-  assert(isa<Constant>(V) && "Setting insertion point for unknown value!");
-}
-
-/// Returns a re-written value of Start as an indexed GEP using Base as a
-/// pointer.
-static Value *rewriteGEPAsOffset(Value *Start, Value *Base,
-                                 const DataLayout &DL,
-                                 SetVector<Value *> &Explored) {
-  // Perform all the substitutions. This is a bit tricky because we can
-  // have cycles in our use-def chains.
-  // 1. Create the PHI nodes without any incoming values.
-  // 2. Create all the other values.
-  // 3. Add the edges for the PHI nodes.
-  // 4. Emit GEPs to get the original pointers.
-  // 5. Remove the original instructions.
-  Type *IndexType = IntegerType::get(
-      Base->getContext(), DL.getIndexTypeSizeInBits(Start->getType()));
-
-  DenseMap<Value *, Value *> NewInsts;
-  NewInsts[Base] = ConstantInt::getNullValue(IndexType);
-
-  // Create the new PHI nodes, without adding any incoming values.
-  for (Value *Val : Explored) {
-    if (Val == Base)
-      continue;
-    // Create empty phi nodes. This avoids cyclic dependencies when creating
-    // the remaining instructions.
-    if (auto *PHI = dyn_cast<PHINode>(Val))
-      NewInsts[PHI] = PHINode::Create(IndexType, PHI->getNumIncomingValues(),
-                                      PHI->getName() + ".idx", PHI);
-  }
-  IRBuilder<> Builder(Base->getContext());
-
-  // Create all the other instructions.
-  for (Value *Val : Explored) {
-
-    if (NewInsts.find(Val) != NewInsts.end())
-      continue;
-
-    if (auto *CI = dyn_cast<CastInst>(Val)) {
-      NewInsts[CI] = NewInsts[CI->getOperand(0)];
-      continue;
-    }
-    if (auto *GEP = dyn_cast<GEPOperator>(Val)) {
-      Value *Index = NewInsts[GEP->getOperand(1)] ? NewInsts[GEP->getOperand(1)]
-                                                  : GEP->getOperand(1);
-      setInsertionPoint(Builder, GEP);
-      // Indices might need to be sign extended. GEPs will magically do
-      // this, but we need to do it ourselves here.
-      if (Index->getType()->getScalarSizeInBits() !=
-          NewInsts[GEP->getOperand(0)]->getType()->getScalarSizeInBits()) {
-        Index = Builder.CreateSExtOrTrunc(
-            Index, NewInsts[GEP->getOperand(0)]->getType(),
-            GEP->getOperand(0)->getName() + ".sext");
-      }
-
-      auto *Op = NewInsts[GEP->getOperand(0)];
-      if (isa<ConstantInt>(Op) && cast<ConstantInt>(Op)->isZero())
-        NewInsts[GEP] = Index;
-      else
-        NewInsts[GEP] = Builder.CreateNSWAdd(
-            Op, Index, GEP->getOperand(0)->getName() + ".add");
-      continue;
-    }
-    if (isa<PHINode>(Val))
-      continue;
-
-    llvm_unreachable("Unexpected instruction type");
-  }
-
-  // Add the incoming values to the PHI nodes.
-  for (Value *Val : Explored) {
-    if (Val == Base)
-      continue;
-    // All the instructions have been created, we can now add edges to the
-    // phi nodes.
-    if (auto *PHI = dyn_cast<PHINode>(Val)) {
-      PHINode *NewPhi = static_cast<PHINode *>(NewInsts[PHI]);
-      for (unsigned I = 0, E = PHI->getNumIncomingValues(); I < E; ++I) {
-        Value *NewIncoming = PHI->getIncomingValue(I);
-
-        if (NewInsts.find(NewIncoming) != NewInsts.end())
-          NewIncoming = NewInsts[NewIncoming];
-
-        NewPhi->addIncoming(NewIncoming, PHI->getIncomingBlock(I));
-      }
-    }
-  }
-
-  for (Value *Val : Explored) {
-    if (Val == Base)
-      continue;
-
-    // Depending on the type, for external users we have to emit
-    // a GEP or a GEP + ptrtoint.
-    setInsertionPoint(Builder, Val, false);
-
-    // If required, create an inttoptr instruction for Base.
-    Value *NewBase = Base;
-    if (!Base->getType()->isPointerTy())
-      NewBase = Builder.CreateBitOrPointerCast(Base, Start->getType(),
-                                               Start->getName() + "to.ptr");
-
-    Value *GEP = Builder.CreateInBoundsGEP(
-        Start->getType()->getPointerElementType(), NewBase,
-        makeArrayRef(NewInsts[Val]), Val->getName() + ".ptr");
-
-    if (!Val->getType()->isPointerTy()) {
-      Value *Cast = Builder.CreatePointerCast(GEP, Val->getType(),
-                                              Val->getName() + ".conv");
-      GEP = Cast;
-    }
-    Val->replaceAllUsesWith(GEP);
-  }
-
-  return NewInsts[Start];
-}
-
-/// Looks through GEPs, IntToPtrInsts and PtrToIntInsts in order to express
-/// the input Value as a constant indexed GEP. Returns a pair containing
-/// the GEPs Pointer and Index.
-static std::pair<Value *, Value *>
-getAsConstantIndexedAddress(Value *V, const DataLayout &DL) {
-  Type *IndexType = IntegerType::get(V->getContext(),
-                                     DL.getIndexTypeSizeInBits(V->getType()));
-
-  Constant *Index = ConstantInt::getNullValue(IndexType);
-  while (true) {
-    if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
-      // We accept only inbouds GEPs here to exclude the possibility of
-      // overflow.
-      if (!GEP->isInBounds())
-        break;
-      if (GEP->hasAllConstantIndices() && GEP->getNumIndices() == 1 &&
-          GEP->getType() == V->getType()) {
-        V = GEP->getOperand(0);
-        Constant *GEPIndex = static_cast<Constant *>(GEP->getOperand(1));
-        Index = ConstantExpr::getAdd(
-            Index, ConstantExpr::getSExtOrBitCast(GEPIndex, IndexType));
-        continue;
-      }
-      break;
-    }
-    if (auto *CI = dyn_cast<IntToPtrInst>(V)) {
-      if (!CI->isNoopCast(DL))
-        break;
-      V = CI->getOperand(0);
-      continue;
-    }
-    if (auto *CI = dyn_cast<PtrToIntInst>(V)) {
-      if (!CI->isNoopCast(DL))
-        break;
-      V = CI->getOperand(0);
-      continue;
-    }
-    break;
-  }
-  return {V, Index};
-}
-
-/// Converts (CMP GEPLHS, RHS) if this change would make RHS a constant.
-/// We can look through PHIs, GEPs and casts in order to determine a common base
-/// between GEPLHS and RHS.
-static Instruction *transformToIndexedCompare(GEPOperator *GEPLHS, Value *RHS,
-                                              ICmpInst::Predicate Cond,
-                                              const DataLayout &DL) {
-  if (!GEPLHS->hasAllConstantIndices())
-    return nullptr;
-
-  // Make sure the pointers have the same type.
-  if (GEPLHS->getType() != RHS->getType())
-    return nullptr;
-
-  Value *PtrBase, *Index;
-  std::tie(PtrBase, Index) = getAsConstantIndexedAddress(GEPLHS, DL);
-
-  // The set of nodes that will take part in this transformation.
-  SetVector<Value *> Nodes;
-
-  if (!canRewriteGEPAsOffset(RHS, PtrBase, DL, Nodes))
-    return nullptr;
-
-  // We know we can re-write this as
-  //  ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2)
-  // Since we've only looked through inbouds GEPs we know that we
-  // can't have overflow on either side. We can therefore re-write
-  // this as:
-  //   OFFSET1 cmp OFFSET2
-  Value *NewRHS = rewriteGEPAsOffset(RHS, PtrBase, DL, Nodes);
-
-  // RewriteGEPAsOffset has replaced RHS and all of its uses with a re-written
-  // GEP having PtrBase as the pointer base, and has returned in NewRHS the
-  // offset. Since Index is the offset of LHS to the base pointer, we will now
-  // compare the offsets instead of comparing the pointers.
-  return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Index, NewRHS);
-}
-
-/// Fold comparisons between a GEP instruction and something else. At this point
-/// we know that the GEP is on the LHS of the comparison.
-Instruction *InstCombiner::foldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
-                                       ICmpInst::Predicate Cond,
-                                       Instruction &I) {
-  // Don't transform signed compares of GEPs into index compares. Even if the
-  // GEP is inbounds, the final add of the base pointer can have signed overflow
-  // and would change the result of the icmp.
-  // e.g. "&foo[0] <s &foo[1]" can't be folded to "true" because "foo" could be
-  // the maximum signed value for the pointer type.
-  if (ICmpInst::isSigned(Cond))
-    return nullptr;
-
-  // Look through bitcasts and addrspacecasts. We do not however want to remove
-  // 0 GEPs.
-  if (!isa<GetElementPtrInst>(RHS))
-    RHS = RHS->stripPointerCasts();
-
-  Value *PtrBase = GEPLHS->getOperand(0);
-  if (PtrBase == RHS && GEPLHS->isInBounds()) {
-    // ((gep Ptr, OFFSET) cmp Ptr)   ---> (OFFSET cmp 0).
-    // This transformation (ignoring the base and scales) is valid because we
-    // know pointers can't overflow since the gep is inbounds.  See if we can
-    // output an optimized form.
-    Value *Offset = evaluateGEPOffsetExpression(GEPLHS, *this, DL);
-
-    // If not, synthesize the offset the hard way.
-    if (!Offset)
-      Offset = EmitGEPOffset(GEPLHS);
-    return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
-                        Constant::getNullValue(Offset->getType()));
-  } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
-    // If the base pointers are different, but the indices are the same, just
-    // compare the base pointer.
-    if (PtrBase != GEPRHS->getOperand(0)) {
-      bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
-      IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
-                        GEPRHS->getOperand(0)->getType();
-      if (IndicesTheSame)
-        for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
-          if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
-            IndicesTheSame = false;
-            break;
-          }
-
-      // If all indices are the same, just compare the base pointers.
-      Type *BaseType = GEPLHS->getOperand(0)->getType();
-      if (IndicesTheSame && CmpInst::makeCmpResultType(BaseType) == I.getType())
-        return new ICmpInst(Cond, GEPLHS->getOperand(0), GEPRHS->getOperand(0));
-
-      // If we're comparing GEPs with two base pointers that only differ in type
-      // and both GEPs have only constant indices or just one use, then fold
-      // the compare with the adjusted indices.
-      if (GEPLHS->isInBounds() && GEPRHS->isInBounds() &&
-          (GEPLHS->hasAllConstantIndices() || GEPLHS->hasOneUse()) &&
-          (GEPRHS->hasAllConstantIndices() || GEPRHS->hasOneUse()) &&
-          PtrBase->stripPointerCasts() ==
-              GEPRHS->getOperand(0)->stripPointerCasts()) {
-        Value *LOffset = EmitGEPOffset(GEPLHS);
-        Value *ROffset = EmitGEPOffset(GEPRHS);
-
-        // If we looked through an addrspacecast between different sized address
-        // spaces, the LHS and RHS pointers are different sized
-        // integers. Truncate to the smaller one.
-        Type *LHSIndexTy = LOffset->getType();
-        Type *RHSIndexTy = ROffset->getType();
-        if (LHSIndexTy != RHSIndexTy) {
-          if (LHSIndexTy->getPrimitiveSizeInBits() <
-              RHSIndexTy->getPrimitiveSizeInBits()) {
-            ROffset = Builder.CreateTrunc(ROffset, LHSIndexTy);
-          } else
-            LOffset = Builder.CreateTrunc(LOffset, RHSIndexTy);
-        }
-
-        Value *Cmp = Builder.CreateICmp(ICmpInst::getSignedPredicate(Cond),
-                                        LOffset, ROffset);
-        return replaceInstUsesWith(I, Cmp);
-      }
-
-      // Otherwise, the base pointers are different and the indices are
-      // different. Try convert this to an indexed compare by looking through
-      // PHIs/casts.
-      return transformToIndexedCompare(GEPLHS, RHS, Cond, DL);
-    }
-
-    // If one of the GEPs has all zero indices, recurse.
-    if (GEPLHS->hasAllZeroIndices())
-      return foldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
-                         ICmpInst::getSwappedPredicate(Cond), I);
-
-    // If the other GEP has all zero indices, recurse.
-    if (GEPRHS->hasAllZeroIndices())
-      return foldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
-
-    bool GEPsInBounds = GEPLHS->isInBounds() && GEPRHS->isInBounds();
-    if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
-      // If the GEPs only differ by one index, compare it.
-      unsigned NumDifferences = 0;  // Keep track of # differences.
-      unsigned DiffOperand = 0;     // The operand that differs.
-      for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
-        if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
-          if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
-                   GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
-            // Irreconcilable differences.
-            NumDifferences = 2;
-            break;
-          } else {
-            if (NumDifferences++) break;
-            DiffOperand = i;
-          }
-        }
-
-      if (NumDifferences == 0)   // SAME GEP?
-        return replaceInstUsesWith(I, // No comparison is needed here.
-          ConstantInt::get(I.getType(), ICmpInst::isTrueWhenEqual(Cond)));
-
-      else if (NumDifferences == 1 && GEPsInBounds) {
-        Value *LHSV = GEPLHS->getOperand(DiffOperand);
-        Value *RHSV = GEPRHS->getOperand(DiffOperand);
-        // Make sure we do a signed comparison here.
-        return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
-      }
-    }
-
-    // Only lower this if the icmp is the only user of the GEP or if we expect
-    // the result to fold to a constant!
-    if (GEPsInBounds && (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
-        (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
-      // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2)  --->  (OFFSET1 cmp OFFSET2)
-      Value *L = EmitGEPOffset(GEPLHS);
-      Value *R = EmitGEPOffset(GEPRHS);
-      return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
-    }
-  }
-
-  // Try convert this to an indexed compare by looking through PHIs/casts as a
-  // last resort.
-  return transformToIndexedCompare(GEPLHS, RHS, Cond, DL);
-}
-
-Instruction *InstCombiner::foldAllocaCmp(ICmpInst &ICI,
-                                         const AllocaInst *Alloca,
-                                         const Value *Other) {
-  assert(ICI.isEquality() && "Cannot fold non-equality comparison.");
-
-  // It would be tempting to fold away comparisons between allocas and any
-  // pointer not based on that alloca (e.g. an argument). However, even
-  // though such pointers cannot alias, they can still compare equal.
-  //
-  // But LLVM doesn't specify where allocas get their memory, so if the alloca
-  // doesn't escape we can argue that it's impossible to guess its value, and we
-  // can therefore act as if any such guesses are wrong.
-  //
-  // The code below checks that the alloca doesn't escape, and that it's only
-  // used in a comparison once (the current instruction). The
-  // single-comparison-use condition ensures that we're trivially folding all
-  // comparisons against the alloca consistently, and avoids the risk of
-  // erroneously folding a comparison of the pointer with itself.
-
-  unsigned MaxIter = 32; // Break cycles and bound to constant-time.
-
-  SmallVector<const Use *, 32> Worklist;
-  for (const Use &U : Alloca->uses()) {
-    if (Worklist.size() >= MaxIter)
-      return nullptr;
-    Worklist.push_back(&U);
-  }
-
-  unsigned NumCmps = 0;
-  while (!Worklist.empty()) {
-    assert(Worklist.size() <= MaxIter);
-    const Use *U = Worklist.pop_back_val();
-    const Value *V = U->getUser();
-    --MaxIter;
-
-    if (isa<BitCastInst>(V) || isa<GetElementPtrInst>(V) || isa<PHINode>(V) ||
-        isa<SelectInst>(V)) {
-      // Track the uses.
-    } else if (isa<LoadInst>(V)) {
-      // Loading from the pointer doesn't escape it.
-      continue;
-    } else if (const auto *SI = dyn_cast<StoreInst>(V)) {
-      // Storing *to* the pointer is fine, but storing the pointer escapes it.
-      if (SI->getValueOperand() == U->get())
-        return nullptr;
-      continue;
-    } else if (isa<ICmpInst>(V)) {
-      if (NumCmps++)
-        return nullptr; // Found more than one cmp.
-      continue;
-    } else if (const auto *Intrin = dyn_cast<IntrinsicInst>(V)) {
-      switch (Intrin->getIntrinsicID()) {
-        // These intrinsics don't escape or compare the pointer. Memset is safe
-        // because we don't allow ptrtoint. Memcpy and memmove are safe because
-        // we don't allow stores, so src cannot point to V.
-        case Intrinsic::lifetime_start: case Intrinsic::lifetime_end:
-        case Intrinsic::memcpy: case Intrinsic::memmove: case Intrinsic::memset:
-          continue;
-        default:
-          return nullptr;
-      }
-    } else {
-      return nullptr;
-    }
-    for (const Use &U : V->uses()) {
-      if (Worklist.size() >= MaxIter)
-        return nullptr;
-      Worklist.push_back(&U);
-    }
-  }
-
-  Type *CmpTy = CmpInst::makeCmpResultType(Other->getType());
-  return replaceInstUsesWith(
-      ICI,
-      ConstantInt::get(CmpTy, !CmpInst::isTrueWhenEqual(ICI.getPredicate())));
-}
-
-/// Fold "icmp pred (X+C), X".
-Instruction *InstCombiner::foldICmpAddOpConst(Value *X, const APInt &C,
-                                              ICmpInst::Predicate Pred) {
-  // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0,
-  // so the values can never be equal.  Similarly for all other "or equals"
-  // operators.
-  assert(!!C && "C should not be zero!");
-
-  // (X+1) <u X        --> X >u (MAXUINT-1)        --> X == 255
-  // (X+2) <u X        --> X >u (MAXUINT-2)        --> X > 253
-  // (X+MAXUINT) <u X  --> X >u (MAXUINT-MAXUINT)  --> X != 0
-  if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) {
-    Constant *R = ConstantInt::get(X->getType(),
-                                   APInt::getMaxValue(C.getBitWidth()) - C);
-    return new ICmpInst(ICmpInst::ICMP_UGT, X, R);
-  }
-
-  // (X+1) >u X        --> X <u (0-1)        --> X != 255
-  // (X+2) >u X        --> X <u (0-2)        --> X <u 254
-  // (X+MAXUINT) >u X  --> X <u (0-MAXUINT)  --> X <u 1  --> X == 0
-  if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE)
-    return new ICmpInst(ICmpInst::ICMP_ULT, X,
-                        ConstantInt::get(X->getType(), -C));
-
-  APInt SMax = APInt::getSignedMaxValue(C.getBitWidth());
-
-  // (X+ 1) <s X       --> X >s (MAXSINT-1)          --> X == 127
-  // (X+ 2) <s X       --> X >s (MAXSINT-2)          --> X >s 125
-  // (X+MAXSINT) <s X  --> X >s (MAXSINT-MAXSINT)    --> X >s 0
-  // (X+MINSINT) <s X  --> X >s (MAXSINT-MINSINT)    --> X >s -1
-  // (X+ -2) <s X      --> X >s (MAXSINT- -2)        --> X >s 126
-  // (X+ -1) <s X      --> X >s (MAXSINT- -1)        --> X != 127
-  if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
-    return new ICmpInst(ICmpInst::ICMP_SGT, X,
-                        ConstantInt::get(X->getType(), SMax - C));
-
-  // (X+ 1) >s X       --> X <s (MAXSINT-(1-1))       --> X != 127
-  // (X+ 2) >s X       --> X <s (MAXSINT-(2-1))       --> X <s 126
-  // (X+MAXSINT) >s X  --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1
-  // (X+MINSINT) >s X  --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2
-  // (X+ -2) >s X      --> X <s (MAXSINT-(-2-1))      --> X <s -126
-  // (X+ -1) >s X      --> X <s (MAXSINT-(-1-1))      --> X == -128
-
-  assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE);
-  return new ICmpInst(ICmpInst::ICMP_SLT, X,
-                      ConstantInt::get(X->getType(), SMax - (C - 1)));
-}
-
-/// Handle "(icmp eq/ne (ashr/lshr AP2, A), AP1)" ->
-/// (icmp eq/ne A, Log2(AP2/AP1)) ->
-/// (icmp eq/ne A, Log2(AP2) - Log2(AP1)).
-Instruction *InstCombiner::foldICmpShrConstConst(ICmpInst &I, Value *A,
-                                                 const APInt &AP1,
-                                                 const APInt &AP2) {
-  assert(I.isEquality() && "Cannot fold icmp gt/lt");
-
-  auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) {
-    if (I.getPredicate() == I.ICMP_NE)
-      Pred = CmpInst::getInversePredicate(Pred);
-    return new ICmpInst(Pred, LHS, RHS);
-  };
-
-  // Don't bother doing any work for cases which InstSimplify handles.
-  if (AP2.isNullValue())
-    return nullptr;
-
-  bool IsAShr = isa<AShrOperator>(I.getOperand(0));
-  if (IsAShr) {
-    if (AP2.isAllOnesValue())
-      return nullptr;
-    if (AP2.isNegative() != AP1.isNegative())
-      return nullptr;
-    if (AP2.sgt(AP1))
-      return nullptr;
-  }
-
-  if (!AP1)
-    // 'A' must be large enough to shift out the highest set bit.
-    return getICmp(I.ICMP_UGT, A,
-                   ConstantInt::get(A->getType(), AP2.logBase2()));
-
-  if (AP1 == AP2)
-    return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));
-
-  int Shift;
-  if (IsAShr && AP1.isNegative())
-    Shift = AP1.countLeadingOnes() - AP2.countLeadingOnes();
-  else
-    Shift = AP1.countLeadingZeros() - AP2.countLeadingZeros();
-
-  if (Shift > 0) {
-    if (IsAShr && AP1 == AP2.ashr(Shift)) {
-      // There are multiple solutions if we are comparing against -1 and the LHS
-      // of the ashr is not a power of two.
-      if (AP1.isAllOnesValue() && !AP2.isPowerOf2())
-        return getICmp(I.ICMP_UGE, A, ConstantInt::get(A->getType(), Shift));
-      return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
-    } else if (AP1 == AP2.lshr(Shift)) {
-      return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
-    }
-  }
-
-  // Shifting const2 will never be equal to const1.
-  // FIXME: This should always be handled by InstSimplify?
-  auto *TorF = ConstantInt::get(I.getType(), I.getPredicate() == I.ICMP_NE);
-  return replaceInstUsesWith(I, TorF);
-}
-
-/// Handle "(icmp eq/ne (shl AP2, A), AP1)" ->
-/// (icmp eq/ne A, TrailingZeros(AP1) - TrailingZeros(AP2)).
-Instruction *InstCombiner::foldICmpShlConstConst(ICmpInst &I, Value *A,
-                                                 const APInt &AP1,
-                                                 const APInt &AP2) {
-  assert(I.isEquality() && "Cannot fold icmp gt/lt");
-
-  auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) {
-    if (I.getPredicate() == I.ICMP_NE)
-      Pred = CmpInst::getInversePredicate(Pred);
-    return new ICmpInst(Pred, LHS, RHS);
-  };
-
-  // Don't bother doing any work for cases which InstSimplify handles.
-  if (AP2.isNullValue())
-    return nullptr;
-
-  unsigned AP2TrailingZeros = AP2.countTrailingZeros();
-
-  if (!AP1 && AP2TrailingZeros != 0)
-    return getICmp(
-        I.ICMP_UGE, A,
-        ConstantInt::get(A->getType(), AP2.getBitWidth() - AP2TrailingZeros));
-
-  if (AP1 == AP2)
-    return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));
-
-  // Get the distance between the lowest bits that are set.
-  int Shift = AP1.countTrailingZeros() - AP2TrailingZeros;
-
-  if (Shift > 0 && AP2.shl(Shift) == AP1)
-    return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
-
-  // Shifting const2 will never be equal to const1.
-  // FIXME: This should always be handled by InstSimplify?
-  auto *TorF = ConstantInt::get(I.getType(), I.getPredicate() == I.ICMP_NE);
-  return replaceInstUsesWith(I, TorF);
-}
-
-/// The caller has matched a pattern of the form:
-///   I = icmp ugt (add (add A, B), CI2), CI1
-/// If this is of the form:
-///   sum = a + b
-///   if (sum+128 >u 255)
-/// Then replace it with llvm.sadd.with.overflow.i8.
-///
-static Instruction *processUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
-                                          ConstantInt *CI2, ConstantInt *CI1,
-                                          InstCombiner &IC) {
-  // The transformation we're trying to do here is to transform this into an
-  // llvm.sadd.with.overflow.  To do this, we have to replace the original add
-  // with a narrower add, and discard the add-with-constant that is part of the
-  // range check (if we can't eliminate it, this isn't profitable).
-
-  // In order to eliminate the add-with-constant, the compare can be its only
-  // use.
-  Instruction *AddWithCst = cast<Instruction>(I.getOperand(0));
-  if (!AddWithCst->hasOneUse())
-    return nullptr;
-
-  // If CI2 is 2^7, 2^15, 2^31, then it might be an sadd.with.overflow.
-  if (!CI2->getValue().isPowerOf2())
-    return nullptr;
-  unsigned NewWidth = CI2->getValue().countTrailingZeros();
-  if (NewWidth != 7 && NewWidth != 15 && NewWidth != 31)
-    return nullptr;
-
-  // The width of the new add formed is 1 more than the bias.
-  ++NewWidth;
-
-  // Check to see that CI1 is an all-ones value with NewWidth bits.
-  if (CI1->getBitWidth() == NewWidth ||
-      CI1->getValue() != APInt::getLowBitsSet(CI1->getBitWidth(), NewWidth))
-    return nullptr;
-
-  // This is only really a signed overflow check if the inputs have been
-  // sign-extended; check for that condition. For example, if CI2 is 2^31 and
-  // the operands of the add are 64 bits wide, we need at least 33 sign bits.
-  unsigned NeededSignBits = CI1->getBitWidth() - NewWidth + 1;
-  if (IC.ComputeNumSignBits(A, 0, &I) < NeededSignBits ||
-      IC.ComputeNumSignBits(B, 0, &I) < NeededSignBits)
-    return nullptr;
-
-  // In order to replace the original add with a narrower
-  // llvm.sadd.with.overflow, the only uses allowed are the add-with-constant
-  // and truncates that discard the high bits of the add.  Verify that this is
-  // the case.
-  Instruction *OrigAdd = cast<Instruction>(AddWithCst->getOperand(0));
-  for (User *U : OrigAdd->users()) {
-    if (U == AddWithCst)
-      continue;
-
-    // Only accept truncates for now.  We would really like a nice recursive
-    // predicate like SimplifyDemandedBits, but which goes downwards the use-def
-    // chain to see which bits of a value are actually demanded.  If the
-    // original add had another add which was then immediately truncated, we
-    // could still do the transformation.
-    TruncInst *TI = dyn_cast<TruncInst>(U);
-    if (!TI || TI->getType()->getPrimitiveSizeInBits() > NewWidth)
-      return nullptr;
-  }
-
-  // If the pattern matches, truncate the inputs to the narrower type and
-  // use the sadd_with_overflow intrinsic to efficiently compute both the
-  // result and the overflow bit.
-  Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth);
-  Value *F = Intrinsic::getDeclaration(I.getModule(),
-                                       Intrinsic::sadd_with_overflow, NewType);
-
-  InstCombiner::BuilderTy &Builder = IC.Builder;
-
-  // Put the new code above the original add, in case there are any uses of the
-  // add between the add and the compare.
-  Builder.SetInsertPoint(OrigAdd);
-
-  Value *TruncA = Builder.CreateTrunc(A, NewType, A->getName() + ".trunc");
-  Value *TruncB = Builder.CreateTrunc(B, NewType, B->getName() + ".trunc");
-  CallInst *Call = Builder.CreateCall(F, {TruncA, TruncB}, "sadd");
-  Value *Add = Builder.CreateExtractValue(Call, 0, "sadd.result");
-  Value *ZExt = Builder.CreateZExt(Add, OrigAdd->getType());
-
-  // The inner add was the result of the narrow add, zero extended to the
-  // wider type.  Replace it with the result computed by the intrinsic.
-  IC.replaceInstUsesWith(*OrigAdd, ZExt);
-
-  // The original icmp gets replaced with the overflow value.
-  return ExtractValueInst::Create(Call, 1, "sadd.overflow");
-}
-
-// Handle (icmp sgt smin(PosA, B) 0) -> (icmp sgt B 0)
-Instruction *InstCombiner::foldICmpWithZero(ICmpInst &Cmp) {
-  CmpInst::Predicate Pred = Cmp.getPredicate();
-  Value *X = Cmp.getOperand(0);
-
-  if (match(Cmp.getOperand(1), m_Zero()) && Pred == ICmpInst::ICMP_SGT) {
-    Value *A, *B;
-    SelectPatternResult SPR = matchSelectPattern(X, A, B);
-    if (SPR.Flavor == SPF_SMIN) {
-      if (isKnownPositive(A, DL, 0, &AC, &Cmp, &DT))
-        return new ICmpInst(Pred, B, Cmp.getOperand(1));
-      if (isKnownPositive(B, DL, 0, &AC, &Cmp, &DT))
-        return new ICmpInst(Pred, A, Cmp.getOperand(1));
-    }
-  }
-  return nullptr;
-}
-
-/// Fold icmp Pred X, C.
-/// TODO: This code structure does not make sense. The saturating add fold
-/// should be moved to some other helper and extended as noted below (it is also
-/// possible that code has been made unnecessary - do we canonicalize IR to
-/// overflow/saturating intrinsics or not?).
-Instruction *InstCombiner::foldICmpWithConstant(ICmpInst &Cmp) {
-  // Match the following pattern, which is a common idiom when writing
-  // overflow-safe integer arithmetic functions. The source performs an addition
-  // in wider type and explicitly checks for overflow using comparisons against
-  // INT_MIN and INT_MAX. Simplify by using the sadd_with_overflow intrinsic.
-  //
-  // TODO: This could probably be generalized to handle other overflow-safe
-  // operations if we worked out the formulas to compute the appropriate magic
-  // constants.
-  //
-  // sum = a + b
-  // if (sum+128 >u 255)  ...  -> llvm.sadd.with.overflow.i8
-  CmpInst::Predicate Pred = Cmp.getPredicate();
-  Value *Op0 = Cmp.getOperand(0), *Op1 = Cmp.getOperand(1);
-  Value *A, *B;
-  ConstantInt *CI, *CI2; // I = icmp ugt (add (add A, B), CI2), CI
-  if (Pred == ICmpInst::ICMP_UGT && match(Op1, m_ConstantInt(CI)) &&
-      match(Op0, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2))))
-    if (Instruction *Res = processUGT_ADDCST_ADD(Cmp, A, B, CI2, CI, *this))
-      return Res;
-
-  return nullptr;
-}
-
-/// Canonicalize icmp instructions based on dominating conditions.
-Instruction *InstCombiner::foldICmpWithDominatingICmp(ICmpInst &Cmp) {
-  // This is a cheap/incomplete check for dominance - just match a single
-  // predecessor with a conditional branch.
-  BasicBlock *CmpBB = Cmp.getParent();
-  BasicBlock *DomBB = CmpBB->getSinglePredecessor();
-  if (!DomBB)
-    return nullptr;
-
-  Value *DomCond;
-  BasicBlock *TrueBB, *FalseBB;
-  if (!match(DomBB->getTerminator(), m_Br(m_Value(DomCond), TrueBB, FalseBB)))
-    return nullptr;
-
-  assert((TrueBB == CmpBB || FalseBB == CmpBB) &&
-         "Predecessor block does not point to successor?");
-
-  // The branch should get simplified. Don't bother simplifying this condition.
-  if (TrueBB == FalseBB)
-    return nullptr;
-
-  // Try to simplify this compare to T/F based on the dominating condition.
-  Optional<bool> Imp = isImpliedCondition(DomCond, &Cmp, DL, TrueBB == CmpBB);
-  if (Imp)
-    return replaceInstUsesWith(Cmp, ConstantInt::get(Cmp.getType(), *Imp));
-
-  CmpInst::Predicate Pred = Cmp.getPredicate();
-  Value *X = Cmp.getOperand(0), *Y = Cmp.getOperand(1);
-  ICmpInst::Predicate DomPred;
-  const APInt *C, *DomC;
-  if (match(DomCond, m_ICmp(DomPred, m_Specific(X), m_APInt(DomC))) &&
-      match(Y, m_APInt(C))) {
-    // We have 2 compares of a variable with constants. Calculate the constant
-    // ranges of those compares to see if we can transform the 2nd compare:
-    // DomBB:
-    //   DomCond = icmp DomPred X, DomC
-    //   br DomCond, CmpBB, FalseBB
-    // CmpBB:
-    //   Cmp = icmp Pred X, C
-    ConstantRange CR = ConstantRange::makeAllowedICmpRegion(Pred, *C);
-    ConstantRange DominatingCR =
-        (CmpBB == TrueBB) ? ConstantRange::makeExactICmpRegion(DomPred, *DomC)
-                          : ConstantRange::makeExactICmpRegion(
-                                CmpInst::getInversePredicate(DomPred), *DomC);
-    ConstantRange Intersection = DominatingCR.intersectWith(CR);
-    ConstantRange Difference = DominatingCR.difference(CR);
-    if (Intersection.isEmptySet())
-      return replaceInstUsesWith(Cmp, Builder.getFalse());
-    if (Difference.isEmptySet())
-      return replaceInstUsesWith(Cmp, Builder.getTrue());
-
-    // Canonicalizing a sign bit comparison that gets used in a branch,
-    // pessimizes codegen by generating branch on zero instruction instead
-    // of a test and branch. So we avoid canonicalizing in such situations
-    // because test and branch instruction has better branch displacement
-    // than compare and branch instruction.
-    bool UnusedBit;
-    bool IsSignBit = isSignBitCheck(Pred, *C, UnusedBit);
-    if (Cmp.isEquality() || (IsSignBit && hasBranchUse(Cmp)))
-      return nullptr;
-
-    if (const APInt *EqC = Intersection.getSingleElement())
-      return new ICmpInst(ICmpInst::ICMP_EQ, X, Builder.getInt(*EqC));
-    if (const APInt *NeC = Difference.getSingleElement())
-      return new ICmpInst(ICmpInst::ICMP_NE, X, Builder.getInt(*NeC));
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp (trunc X, Y), C.
-Instruction *InstCombiner::foldICmpTruncConstant(ICmpInst &Cmp,
-                                                 TruncInst *Trunc,
-                                                 const APInt &C) {
-  ICmpInst::Predicate Pred = Cmp.getPredicate();
-  Value *X = Trunc->getOperand(0);
-  if (C.isOneValue() && C.getBitWidth() > 1) {
-    // icmp slt trunc(signum(V)) 1 --> icmp slt V, 1
-    Value *V = nullptr;
-    if (Pred == ICmpInst::ICMP_SLT && match(X, m_Signum(m_Value(V))))
-      return new ICmpInst(ICmpInst::ICMP_SLT, V,
-                          ConstantInt::get(V->getType(), 1));
-  }
-
-  if (Cmp.isEquality() && Trunc->hasOneUse()) {
-    // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
-    // of the high bits truncated out of x are known.
-    unsigned DstBits = Trunc->getType()->getScalarSizeInBits(),
-             SrcBits = X->getType()->getScalarSizeInBits();
-    KnownBits Known = computeKnownBits(X, 0, &Cmp);
-
-    // If all the high bits are known, we can do this xform.
-    if ((Known.Zero | Known.One).countLeadingOnes() >= SrcBits - DstBits) {
-      // Pull in the high bits from known-ones set.
-      APInt NewRHS = C.zext(SrcBits);
-      NewRHS |= Known.One & APInt::getHighBitsSet(SrcBits, SrcBits - DstBits);
-      return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), NewRHS));
-    }
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp (xor X, Y), C.
-Instruction *InstCombiner::foldICmpXorConstant(ICmpInst &Cmp,
-                                               BinaryOperator *Xor,
-                                               const APInt &C) {
-  Value *X = Xor->getOperand(0);
-  Value *Y = Xor->getOperand(1);
-  const APInt *XorC;
-  if (!match(Y, m_APInt(XorC)))
-    return nullptr;
-
-  // If this is a comparison that tests the signbit (X < 0) or (x > -1),
-  // fold the xor.
-  ICmpInst::Predicate Pred = Cmp.getPredicate();
-  bool TrueIfSigned = false;
-  if (isSignBitCheck(Cmp.getPredicate(), C, TrueIfSigned)) {
-
-    // If the sign bit of the XorCst is not set, there is no change to
-    // the operation, just stop using the Xor.
-    if (!XorC->isNegative()) {
-      Cmp.setOperand(0, X);
-      Worklist.Add(Xor);
-      return &Cmp;
-    }
-
-    // Emit the opposite comparison.
-    if (TrueIfSigned)
-      return new ICmpInst(ICmpInst::ICMP_SGT, X,
-                          ConstantInt::getAllOnesValue(X->getType()));
-    else
-      return new ICmpInst(ICmpInst::ICMP_SLT, X,
-                          ConstantInt::getNullValue(X->getType()));
-  }
-
-  if (Xor->hasOneUse()) {
-    // (icmp u/s (xor X SignMask), C) -> (icmp s/u X, (xor C SignMask))
-    if (!Cmp.isEquality() && XorC->isSignMask()) {
-      Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate()
-                            : Cmp.getSignedPredicate();
-      return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), C ^ *XorC));
-    }
-
-    // (icmp u/s (xor X ~SignMask), C) -> (icmp s/u X, (xor C ~SignMask))
-    if (!Cmp.isEquality() && XorC->isMaxSignedValue()) {
-      Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate()
-                            : Cmp.getSignedPredicate();
-      Pred = Cmp.getSwappedPredicate(Pred);
-      return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), C ^ *XorC));
-    }
-  }
-
-  // Mask constant magic can eliminate an 'xor' with unsigned compares.
-  if (Pred == ICmpInst::ICMP_UGT) {
-    // (xor X, ~C) >u C --> X <u ~C (when C+1 is a power of 2)
-    if (*XorC == ~C && (C + 1).isPowerOf2())
-      return new ICmpInst(ICmpInst::ICMP_ULT, X, Y);
-    // (xor X, C) >u C --> X >u C (when C+1 is a power of 2)
-    if (*XorC == C && (C + 1).isPowerOf2())
-      return new ICmpInst(ICmpInst::ICMP_UGT, X, Y);
-  }
-  if (Pred == ICmpInst::ICMP_ULT) {
-    // (xor X, -C) <u C --> X >u ~C (when C is a power of 2)
-    if (*XorC == -C && C.isPowerOf2())
-      return new ICmpInst(ICmpInst::ICMP_UGT, X,
-                          ConstantInt::get(X->getType(), ~C));
-    // (xor X, C) <u C --> X >u ~C (when -C is a power of 2)
-    if (*XorC == C && (-C).isPowerOf2())
-      return new ICmpInst(ICmpInst::ICMP_UGT, X,
-                          ConstantInt::get(X->getType(), ~C));
-  }
-  return nullptr;
-}
-
-/// Fold icmp (and (sh X, Y), C2), C1.
-Instruction *InstCombiner::foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And,
-                                            const APInt &C1, const APInt &C2) {
-  BinaryOperator *Shift = dyn_cast<BinaryOperator>(And->getOperand(0));
-  if (!Shift || !Shift->isShift())
-    return nullptr;
-
-  // If this is: (X >> C3) & C2 != C1 (where any shift and any compare could
-  // exist), turn it into (X & (C2 << C3)) != (C1 << C3). This happens a LOT in
-  // code produced by the clang front-end, for bitfield access.
-  // This seemingly simple opportunity to fold away a shift turns out to be
-  // rather complicated. See PR17827 for details.
-  unsigned ShiftOpcode = Shift->getOpcode();
-  bool IsShl = ShiftOpcode == Instruction::Shl;
-  const APInt *C3;
-  if (match(Shift->getOperand(1), m_APInt(C3))) {
-    bool CanFold = false;
-    if (ShiftOpcode == Instruction::Shl) {
-      // For a left shift, we can fold if the comparison is not signed. We can
-      // also fold a signed comparison if the mask value and comparison value
-      // are not negative. These constraints may not be obvious, but we can
-      // prove that they are correct using an SMT solver.
-      if (!Cmp.isSigned() || (!C2.isNegative() && !C1.isNegative()))
-        CanFold = true;
-    } else {
-      bool IsAshr = ShiftOpcode == Instruction::AShr;
-      // For a logical right shift, we can fold if the comparison is not signed.
-      // We can also fold a signed comparison if the shifted mask value and the
-      // shifted comparison value are not negative. These constraints may not be
-      // obvious, but we can prove that they are correct using an SMT solver.
-      // For an arithmetic shift right we can do the same, if we ensure
-      // the And doesn't use any bits being shifted in. Normally these would
-      // be turned into lshr by SimplifyDemandedBits, but not if there is an
-      // additional user.
-      if (!IsAshr || (C2.shl(*C3).lshr(*C3) == C2)) {
-        if (!Cmp.isSigned() ||
-            (!C2.shl(*C3).isNegative() && !C1.shl(*C3).isNegative()))
-          CanFold = true;
-      }
-    }
-
-    if (CanFold) {
-      APInt NewCst = IsShl ? C1.lshr(*C3) : C1.shl(*C3);
-      APInt SameAsC1 = IsShl ? NewCst.shl(*C3) : NewCst.lshr(*C3);
-      // Check to see if we are shifting out any of the bits being compared.
-      if (SameAsC1 != C1) {
-        // If we shifted bits out, the fold is not going to work out. As a
-        // special case, check to see if this means that the result is always
-        // true or false now.
-        if (Cmp.getPredicate() == ICmpInst::ICMP_EQ)
-          return replaceInstUsesWith(Cmp, ConstantInt::getFalse(Cmp.getType()));
-        if (Cmp.getPredicate() == ICmpInst::ICMP_NE)
-          return replaceInstUsesWith(Cmp, ConstantInt::getTrue(Cmp.getType()));
-      } else {
-        Cmp.setOperand(1, ConstantInt::get(And->getType(), NewCst));
-        APInt NewAndCst = IsShl ? C2.lshr(*C3) : C2.shl(*C3);
-        And->setOperand(1, ConstantInt::get(And->getType(), NewAndCst));
-        And->setOperand(0, Shift->getOperand(0));
-        Worklist.Add(Shift); // Shift is dead.
-        return &Cmp;
-      }
-    }
-  }
-
-  // Turn ((X >> Y) & C2) == 0  into  (X & (C2 << Y)) == 0.  The latter is
-  // preferable because it allows the C2 << Y expression to be hoisted out of a
-  // loop if Y is invariant and X is not.
-  if (Shift->hasOneUse() && C1.isNullValue() && Cmp.isEquality() &&
-      !Shift->isArithmeticShift() && !isa<Constant>(Shift->getOperand(0))) {
-    // Compute C2 << Y.
-    Value *NewShift =
-        IsShl ? Builder.CreateLShr(And->getOperand(1), Shift->getOperand(1))
-              : Builder.CreateShl(And->getOperand(1), Shift->getOperand(1));
-
-    // Compute X & (C2 << Y).
-    Value *NewAnd = Builder.CreateAnd(Shift->getOperand(0), NewShift);
-    Cmp.setOperand(0, NewAnd);
-    return &Cmp;
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp (and X, C2), C1.
-Instruction *InstCombiner::foldICmpAndConstConst(ICmpInst &Cmp,
-                                                 BinaryOperator *And,
-                                                 const APInt &C1) {
-  // For vectors: icmp ne (and X, 1), 0 --> trunc X to N x i1
-  // TODO: We canonicalize to the longer form for scalars because we have
-  // better analysis/folds for icmp, and codegen may be better with icmp.
-  if (Cmp.getPredicate() == CmpInst::ICMP_NE && Cmp.getType()->isVectorTy() &&
-      C1.isNullValue() && match(And->getOperand(1), m_One()))
-    return new TruncInst(And->getOperand(0), Cmp.getType());
-
-  const APInt *C2;
-  if (!match(And->getOperand(1), m_APInt(C2)))
-    return nullptr;
-
-  if (!And->hasOneUse())
-    return nullptr;
-
-  // If the LHS is an 'and' of a truncate and we can widen the and/compare to
-  // the input width without changing the value produced, eliminate the cast:
-  //
-  // icmp (and (trunc W), C2), C1 -> icmp (and W, C2'), C1'
-  //
-  // We can do this transformation if the constants do not have their sign bits
-  // set or if it is an equality comparison. Extending a relational comparison
-  // when we're checking the sign bit would not work.
-  Value *W;
-  if (match(And->getOperand(0), m_OneUse(m_Trunc(m_Value(W)))) &&
-      (Cmp.isEquality() || (!C1.isNegative() && !C2->isNegative()))) {
-    // TODO: Is this a good transform for vectors? Wider types may reduce
-    // throughput. Should this transform be limited (even for scalars) by using
-    // shouldChangeType()?
-    if (!Cmp.getType()->isVectorTy()) {
-      Type *WideType = W->getType();
-      unsigned WideScalarBits = WideType->getScalarSizeInBits();
-      Constant *ZextC1 = ConstantInt::get(WideType, C1.zext(WideScalarBits));
-      Constant *ZextC2 = ConstantInt::get(WideType, C2->zext(WideScalarBits));
-      Value *NewAnd = Builder.CreateAnd(W, ZextC2, And->getName());
-      return new ICmpInst(Cmp.getPredicate(), NewAnd, ZextC1);
-    }
-  }
-
-  if (Instruction *I = foldICmpAndShift(Cmp, And, C1, *C2))
-    return I;
-
-  // (icmp pred (and (or (lshr A, B), A), 1), 0) -->
-  // (icmp pred (and A, (or (shl 1, B), 1), 0))
-  //
-  // iff pred isn't signed
-  if (!Cmp.isSigned() && C1.isNullValue() && And->getOperand(0)->hasOneUse() &&
-      match(And->getOperand(1), m_One())) {
-    Constant *One = cast<Constant>(And->getOperand(1));
-    Value *Or = And->getOperand(0);
-    Value *A, *B, *LShr;
-    if (match(Or, m_Or(m_Value(LShr), m_Value(A))) &&
-        match(LShr, m_LShr(m_Specific(A), m_Value(B)))) {
-      unsigned UsesRemoved = 0;
-      if (And->hasOneUse())
-        ++UsesRemoved;
-      if (Or->hasOneUse())
-        ++UsesRemoved;
-      if (LShr->hasOneUse())
-        ++UsesRemoved;
-
-      // Compute A & ((1 << B) | 1)
-      Value *NewOr = nullptr;
-      if (auto *C = dyn_cast<Constant>(B)) {
-        if (UsesRemoved >= 1)
-          NewOr = ConstantExpr::getOr(ConstantExpr::getNUWShl(One, C), One);
-      } else {
-        if (UsesRemoved >= 3)
-          NewOr = Builder.CreateOr(Builder.CreateShl(One, B, LShr->getName(),
-                                                     /*HasNUW=*/true),
-                                   One, Or->getName());
-      }
-      if (NewOr) {
-        Value *NewAnd = Builder.CreateAnd(A, NewOr, And->getName());
-        Cmp.setOperand(0, NewAnd);
-        return &Cmp;
-      }
-    }
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp (and X, Y), C.
-Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &Cmp,
-                                               BinaryOperator *And,
-                                               const APInt &C) {
-  if (Instruction *I = foldICmpAndConstConst(Cmp, And, C))
-    return I;
-
-  // TODO: These all require that Y is constant too, so refactor with the above.
-
-  // Try to optimize things like "A[i] & 42 == 0" to index computations.
-  Value *X = And->getOperand(0);
-  Value *Y = And->getOperand(1);
-  if (auto *LI = dyn_cast<LoadInst>(X))
-    if (auto *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0)))
-      if (auto *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
-        if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
-            !LI->isVolatile() && isa<ConstantInt>(Y)) {
-          ConstantInt *C2 = cast<ConstantInt>(Y);
-          if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, Cmp, C2))
-            return Res;
-        }
-
-  if (!Cmp.isEquality())
-    return nullptr;
-
-  // X & -C == -C -> X >  u ~C
-  // X & -C != -C -> X <= u ~C
-  //   iff C is a power of 2
-  if (Cmp.getOperand(1) == Y && (-C).isPowerOf2()) {
-    auto NewPred = Cmp.getPredicate() == CmpInst::ICMP_EQ ? CmpInst::ICMP_UGT
-                                                          : CmpInst::ICMP_ULE;
-    return new ICmpInst(NewPred, X, SubOne(cast<Constant>(Cmp.getOperand(1))));
-  }
-
-  // (X & C2) == 0 -> (trunc X) >= 0
-  // (X & C2) != 0 -> (trunc X) <  0
-  //   iff C2 is a power of 2 and it masks the sign bit of a legal integer type.
-  const APInt *C2;
-  if (And->hasOneUse() && C.isNullValue() && match(Y, m_APInt(C2))) {
-    int32_t ExactLogBase2 = C2->exactLogBase2();
-    if (ExactLogBase2 != -1 && DL.isLegalInteger(ExactLogBase2 + 1)) {
-      Type *NTy = IntegerType::get(Cmp.getContext(), ExactLogBase2 + 1);
-      if (And->getType()->isVectorTy())
-        NTy = VectorType::get(NTy, And->getType()->getVectorNumElements());
-      Value *Trunc = Builder.CreateTrunc(X, NTy);
-      auto NewPred = Cmp.getPredicate() == CmpInst::ICMP_EQ ? CmpInst::ICMP_SGE
-                                                            : CmpInst::ICMP_SLT;
-      return new ICmpInst(NewPred, Trunc, Constant::getNullValue(NTy));
-    }
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp (or X, Y), C.
-Instruction *InstCombiner::foldICmpOrConstant(ICmpInst &Cmp, BinaryOperator *Or,
-                                              const APInt &C) {
-  ICmpInst::Predicate Pred = Cmp.getPredicate();
-  if (C.isOneValue()) {
-    // icmp slt signum(V) 1 --> icmp slt V, 1
-    Value *V = nullptr;
-    if (Pred == ICmpInst::ICMP_SLT && match(Or, m_Signum(m_Value(V))))
-      return new ICmpInst(ICmpInst::ICMP_SLT, V,
-                          ConstantInt::get(V->getType(), 1));
-  }
-
-  // X | C == C --> X <=u C
-  // X | C != C --> X  >u C
-  //   iff C+1 is a power of 2 (C is a bitmask of the low bits)
-  if (Cmp.isEquality() && Cmp.getOperand(1) == Or->getOperand(1) &&
-      (C + 1).isPowerOf2()) {
-    Pred = (Pred == CmpInst::ICMP_EQ) ? CmpInst::ICMP_ULE : CmpInst::ICMP_UGT;
-    return new ICmpInst(Pred, Or->getOperand(0), Or->getOperand(1));
-  }
-
-  if (!Cmp.isEquality() || !C.isNullValue() || !Or->hasOneUse())
-    return nullptr;
-
-  Value *P, *Q;
-  if (match(Or, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) {
-    // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0
-    // -> and (icmp eq P, null), (icmp eq Q, null).
-    Value *CmpP =
-        Builder.CreateICmp(Pred, P, ConstantInt::getNullValue(P->getType()));
-    Value *CmpQ =
-        Builder.CreateICmp(Pred, Q, ConstantInt::getNullValue(Q->getType()));
-    auto BOpc = Pred == CmpInst::ICMP_EQ ? Instruction::And : Instruction::Or;
-    return BinaryOperator::Create(BOpc, CmpP, CmpQ);
-  }
-
-  // Are we using xors to bitwise check for a pair of (in)equalities? Convert to
-  // a shorter form that has more potential to be folded even further.
-  Value *X1, *X2, *X3, *X4;
-  if (match(Or->getOperand(0), m_OneUse(m_Xor(m_Value(X1), m_Value(X2)))) &&
-      match(Or->getOperand(1), m_OneUse(m_Xor(m_Value(X3), m_Value(X4))))) {
-    // ((X1 ^ X2) || (X3 ^ X4)) == 0 --> (X1 == X2) && (X3 == X4)
-    // ((X1 ^ X2) || (X3 ^ X4)) != 0 --> (X1 != X2) || (X3 != X4)
-    Value *Cmp12 = Builder.CreateICmp(Pred, X1, X2);
-    Value *Cmp34 = Builder.CreateICmp(Pred, X3, X4);
-    auto BOpc = Pred == CmpInst::ICMP_EQ ? Instruction::And : Instruction::Or;
-    return BinaryOperator::Create(BOpc, Cmp12, Cmp34);
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp (mul X, Y), C.
-Instruction *InstCombiner::foldICmpMulConstant(ICmpInst &Cmp,
-                                               BinaryOperator *Mul,
-                                               const APInt &C) {
-  const APInt *MulC;
-  if (!match(Mul->getOperand(1), m_APInt(MulC)))
-    return nullptr;
-
-  // If this is a test of the sign bit and the multiply is sign-preserving with
-  // a constant operand, use the multiply LHS operand instead.
-  ICmpInst::Predicate Pred = Cmp.getPredicate();
-  if (isSignTest(Pred, C) && Mul->hasNoSignedWrap()) {
-    if (MulC->isNegative())
-      Pred = ICmpInst::getSwappedPredicate(Pred);
-    return new ICmpInst(Pred, Mul->getOperand(0),
-                        Constant::getNullValue(Mul->getType()));
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp (shl 1, Y), C.
-static Instruction *foldICmpShlOne(ICmpInst &Cmp, Instruction *Shl,
-                                   const APInt &C) {
-  Value *Y;
-  if (!match(Shl, m_Shl(m_One(), m_Value(Y))))
-    return nullptr;
-
-  Type *ShiftType = Shl->getType();
-  unsigned TypeBits = C.getBitWidth();
-  bool CIsPowerOf2 = C.isPowerOf2();
-  ICmpInst::Predicate Pred = Cmp.getPredicate();
-  if (Cmp.isUnsigned()) {
-    // (1 << Y) pred C -> Y pred Log2(C)
-    if (!CIsPowerOf2) {
-      // (1 << Y) <  30 -> Y <= 4
-      // (1 << Y) <= 30 -> Y <= 4
-      // (1 << Y) >= 30 -> Y >  4
-      // (1 << Y) >  30 -> Y >  4
-      if (Pred == ICmpInst::ICMP_ULT)
-        Pred = ICmpInst::ICMP_ULE;
-      else if (Pred == ICmpInst::ICMP_UGE)
-        Pred = ICmpInst::ICMP_UGT;
-    }
-
-    // (1 << Y) >= 2147483648 -> Y >= 31 -> Y == 31
-    // (1 << Y) <  2147483648 -> Y <  31 -> Y != 31
-    unsigned CLog2 = C.logBase2();
-    if (CLog2 == TypeBits - 1) {
-      if (Pred == ICmpInst::ICMP_UGE)
-        Pred = ICmpInst::ICMP_EQ;
-      else if (Pred == ICmpInst::ICMP_ULT)
-        Pred = ICmpInst::ICMP_NE;
-    }
-    return new ICmpInst(Pred, Y, ConstantInt::get(ShiftType, CLog2));
-  } else if (Cmp.isSigned()) {
-    Constant *BitWidthMinusOne = ConstantInt::get(ShiftType, TypeBits - 1);
-    if (C.isAllOnesValue()) {
-      // (1 << Y) <= -1 -> Y == 31
-      if (Pred == ICmpInst::ICMP_SLE)
-        return new ICmpInst(ICmpInst::ICMP_EQ, Y, BitWidthMinusOne);
-
-      // (1 << Y) >  -1 -> Y != 31
-      if (Pred == ICmpInst::ICMP_SGT)
-        return new ICmpInst(ICmpInst::ICMP_NE, Y, BitWidthMinusOne);
-    } else if (!C) {
-      // (1 << Y) <  0 -> Y == 31
-      // (1 << Y) <= 0 -> Y == 31
-      if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
-        return new ICmpInst(ICmpInst::ICMP_EQ, Y, BitWidthMinusOne);
-
-      // (1 << Y) >= 0 -> Y != 31
-      // (1 << Y) >  0 -> Y != 31
-      if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE)
-        return new ICmpInst(ICmpInst::ICMP_NE, Y, BitWidthMinusOne);
-    }
-  } else if (Cmp.isEquality() && CIsPowerOf2) {
-    return new ICmpInst(Pred, Y, ConstantInt::get(ShiftType, C.logBase2()));
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp (shl X, Y), C.
-Instruction *InstCombiner::foldICmpShlConstant(ICmpInst &Cmp,
-                                               BinaryOperator *Shl,
-                                               const APInt &C) {
-  const APInt *ShiftVal;
-  if (Cmp.isEquality() && match(Shl->getOperand(0), m_APInt(ShiftVal)))
-    return foldICmpShlConstConst(Cmp, Shl->getOperand(1), C, *ShiftVal);
-
-  const APInt *ShiftAmt;
-  if (!match(Shl->getOperand(1), m_APInt(ShiftAmt)))
-    return foldICmpShlOne(Cmp, Shl, C);
-
-  // Check that the shift amount is in range. If not, don't perform undefined
-  // shifts. When the shift is visited, it will be simplified.
-  unsigned TypeBits = C.getBitWidth();
-  if (ShiftAmt->uge(TypeBits))
-    return nullptr;
-
-  ICmpInst::Predicate Pred = Cmp.getPredicate();
-  Value *X = Shl->getOperand(0);
-  Type *ShType = Shl->getType();
-
-  // NSW guarantees that we are only shifting out sign bits from the high bits,
-  // so we can ASHR the compare constant without needing a mask and eliminate
-  // the shift.
-  if (Shl->hasNoSignedWrap()) {
-    if (Pred == ICmpInst::ICMP_SGT) {
-      // icmp Pred (shl nsw X, ShiftAmt), C --> icmp Pred X, (C >>s ShiftAmt)
-      APInt ShiftedC = C.ashr(*ShiftAmt);
-      return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
-    }
-    if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) &&
-        C.ashr(*ShiftAmt).shl(*ShiftAmt) == C) {
-      APInt ShiftedC = C.ashr(*ShiftAmt);
-      return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
-    }
-    if (Pred == ICmpInst::ICMP_SLT) {
-      // SLE is the same as above, but SLE is canonicalized to SLT, so convert:
-      // (X << S) <=s C is equiv to X <=s (C >> S) for all C
-      // (X << S) <s (C + 1) is equiv to X <s (C >> S) + 1 if C <s SMAX
-      // (X << S) <s C is equiv to X <s ((C - 1) >> S) + 1 if C >s SMIN
-      assert(!C.isMinSignedValue() && "Unexpected icmp slt");
-      APInt ShiftedC = (C - 1).ashr(*ShiftAmt) + 1;
-      return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
-    }
-    // If this is a signed comparison to 0 and the shift is sign preserving,
-    // use the shift LHS operand instead; isSignTest may change 'Pred', so only
-    // do that if we're sure to not continue on in this function.
-    if (isSignTest(Pred, C))
-      return new ICmpInst(Pred, X, Constant::getNullValue(ShType));
-  }
-
-  // NUW guarantees that we are only shifting out zero bits from the high bits,
-  // so we can LSHR the compare constant without needing a mask and eliminate
-  // the shift.
-  if (Shl->hasNoUnsignedWrap()) {
-    if (Pred == ICmpInst::ICMP_UGT) {
-      // icmp Pred (shl nuw X, ShiftAmt), C --> icmp Pred X, (C >>u ShiftAmt)
-      APInt ShiftedC = C.lshr(*ShiftAmt);
-      return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
-    }
-    if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) &&
-        C.lshr(*ShiftAmt).shl(*ShiftAmt) == C) {
-      APInt ShiftedC = C.lshr(*ShiftAmt);
-      return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
-    }
-    if (Pred == ICmpInst::ICMP_ULT) {
-      // ULE is the same as above, but ULE is canonicalized to ULT, so convert:
-      // (X << S) <=u C is equiv to X <=u (C >> S) for all C
-      // (X << S) <u (C + 1) is equiv to X <u (C >> S) + 1 if C <u ~0u
-      // (X << S) <u C is equiv to X <u ((C - 1) >> S) + 1 if C >u 0
-      assert(C.ugt(0) && "ult 0 should have been eliminated");
-      APInt ShiftedC = (C - 1).lshr(*ShiftAmt) + 1;
-      return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
-    }
-  }
-
-  if (Cmp.isEquality() && Shl->hasOneUse()) {
-    // Strength-reduce the shift into an 'and'.
-    Constant *Mask = ConstantInt::get(
-        ShType,
-        APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt->getZExtValue()));
-    Value *And = Builder.CreateAnd(X, Mask, Shl->getName() + ".mask");
-    Constant *LShrC = ConstantInt::get(ShType, C.lshr(*ShiftAmt));
-    return new ICmpInst(Pred, And, LShrC);
-  }
-
-  // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
-  bool TrueIfSigned = false;
-  if (Shl->hasOneUse() && isSignBitCheck(Pred, C, TrueIfSigned)) {
-    // (X << 31) <s 0  --> (X & 1) != 0
-    Constant *Mask = ConstantInt::get(
-        ShType,
-        APInt::getOneBitSet(TypeBits, TypeBits - ShiftAmt->getZExtValue() - 1));
-    Value *And = Builder.CreateAnd(X, Mask, Shl->getName() + ".mask");
-    return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
-                        And, Constant::getNullValue(ShType));
-  }
-
-  // Transform (icmp pred iM (shl iM %v, N), C)
-  // -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (C>>N))
-  // Transform the shl to a trunc if (trunc (C>>N)) has no loss and M-N.
-  // This enables us to get rid of the shift in favor of a trunc that may be
-  // free on the target. It has the additional benefit of comparing to a
-  // smaller constant that may be more target-friendly.
-  unsigned Amt = ShiftAmt->getLimitedValue(TypeBits - 1);
-  if (Shl->hasOneUse() && Amt != 0 && C.countTrailingZeros() >= Amt &&
-      DL.isLegalInteger(TypeBits - Amt)) {
-    Type *TruncTy = IntegerType::get(Cmp.getContext(), TypeBits - Amt);
-    if (ShType->isVectorTy())
-      TruncTy = VectorType::get(TruncTy, ShType->getVectorNumElements());
-    Constant *NewC =
-        ConstantInt::get(TruncTy, C.ashr(*ShiftAmt).trunc(TypeBits - Amt));
-    return new ICmpInst(Pred, Builder.CreateTrunc(X, TruncTy), NewC);
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp ({al}shr X, Y), C.
-Instruction *InstCombiner::foldICmpShrConstant(ICmpInst &Cmp,
-                                               BinaryOperator *Shr,
-                                               const APInt &C) {
-  // An exact shr only shifts out zero bits, so:
-  // icmp eq/ne (shr X, Y), 0 --> icmp eq/ne X, 0
-  Value *X = Shr->getOperand(0);
-  CmpInst::Predicate Pred = Cmp.getPredicate();
-  if (Cmp.isEquality() && Shr->isExact() && Shr->hasOneUse() &&
-      C.isNullValue())
-    return new ICmpInst(Pred, X, Cmp.getOperand(1));
-
-  const APInt *ShiftVal;
-  if (Cmp.isEquality() && match(Shr->getOperand(0), m_APInt(ShiftVal)))
-    return foldICmpShrConstConst(Cmp, Shr->getOperand(1), C, *ShiftVal);
-
-  const APInt *ShiftAmt;
-  if (!match(Shr->getOperand(1), m_APInt(ShiftAmt)))
-    return nullptr;
-
-  // Check that the shift amount is in range. If not, don't perform undefined
-  // shifts. When the shift is visited it will be simplified.
-  unsigned TypeBits = C.getBitWidth();
-  unsigned ShAmtVal = ShiftAmt->getLimitedValue(TypeBits);
-  if (ShAmtVal >= TypeBits || ShAmtVal == 0)
-    return nullptr;
-
-  bool IsAShr = Shr->getOpcode() == Instruction::AShr;
-  bool IsExact = Shr->isExact();
-  Type *ShrTy = Shr->getType();
-  // TODO: If we could guarantee that InstSimplify would handle all of the
-  // constant-value-based preconditions in the folds below, then we could assert
-  // those conditions rather than checking them. This is difficult because of
-  // undef/poison (PR34838).
-  if (IsAShr) {
-    if (Pred == CmpInst::ICMP_SLT || (Pred == CmpInst::ICMP_SGT && IsExact)) {
-      // icmp slt (ashr X, ShAmtC), C --> icmp slt X, (C << ShAmtC)
-      // icmp sgt (ashr exact X, ShAmtC), C --> icmp sgt X, (C << ShAmtC)
-      APInt ShiftedC = C.shl(ShAmtVal);
-      if (ShiftedC.ashr(ShAmtVal) == C)
-        return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC));
-    }
-    if (Pred == CmpInst::ICMP_SGT) {
-      // icmp sgt (ashr X, ShAmtC), C --> icmp sgt X, ((C + 1) << ShAmtC) - 1
-      APInt ShiftedC = (C + 1).shl(ShAmtVal) - 1;
-      if (!C.isMaxSignedValue() && !(C + 1).shl(ShAmtVal).isMinSignedValue() &&
-          (ShiftedC + 1).ashr(ShAmtVal) == (C + 1))
-        return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC));
-    }
-  } else {
-    if (Pred == CmpInst::ICMP_ULT || (Pred == CmpInst::ICMP_UGT && IsExact)) {
-      // icmp ult (lshr X, ShAmtC), C --> icmp ult X, (C << ShAmtC)
-      // icmp ugt (lshr exact X, ShAmtC), C --> icmp ugt X, (C << ShAmtC)
-      APInt ShiftedC = C.shl(ShAmtVal);
-      if (ShiftedC.lshr(ShAmtVal) == C)
-        return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC));
-    }
-    if (Pred == CmpInst::ICMP_UGT) {
-      // icmp ugt (lshr X, ShAmtC), C --> icmp ugt X, ((C + 1) << ShAmtC) - 1
-      APInt ShiftedC = (C + 1).shl(ShAmtVal) - 1;
-      if ((ShiftedC + 1).lshr(ShAmtVal) == (C + 1))
-        return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC));
-    }
-  }
-
-  if (!Cmp.isEquality())
-    return nullptr;
-
-  // Handle equality comparisons of shift-by-constant.
-
-  // If the comparison constant changes with the shift, the comparison cannot
-  // succeed (bits of the comparison constant cannot match the shifted value).
-  // This should be known by InstSimplify and already be folded to true/false.
-  assert(((IsAShr && C.shl(ShAmtVal).ashr(ShAmtVal) == C) ||
-          (!IsAShr && C.shl(ShAmtVal).lshr(ShAmtVal) == C)) &&
-         "Expected icmp+shr simplify did not occur.");
-
-  // If the bits shifted out are known zero, compare the unshifted value:
-  //  (X & 4) >> 1 == 2  --> (X & 4) == 4.
-  if (Shr->isExact())
-    return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, C << ShAmtVal));
-
-  if (Shr->hasOneUse()) {
-    // Canonicalize the shift into an 'and':
-    // icmp eq/ne (shr X, ShAmt), C --> icmp eq/ne (and X, HiMask), (C << ShAmt)
-    APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
-    Constant *Mask = ConstantInt::get(ShrTy, Val);
-    Value *And = Builder.CreateAnd(X, Mask, Shr->getName() + ".mask");
-    return new ICmpInst(Pred, And, ConstantInt::get(ShrTy, C << ShAmtVal));
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp (udiv X, Y), C.
-Instruction *InstCombiner::foldICmpUDivConstant(ICmpInst &Cmp,
-                                                BinaryOperator *UDiv,
-                                                const APInt &C) {
-  const APInt *C2;
-  if (!match(UDiv->getOperand(0), m_APInt(C2)))
-    return nullptr;
-
-  assert(*C2 != 0 && "udiv 0, X should have been simplified already.");
-
-  // (icmp ugt (udiv C2, Y), C) -> (icmp ule Y, C2/(C+1))
-  Value *Y = UDiv->getOperand(1);
-  if (Cmp.getPredicate() == ICmpInst::ICMP_UGT) {
-    assert(!C.isMaxValue() &&
-           "icmp ugt X, UINT_MAX should have been simplified already.");
-    return new ICmpInst(ICmpInst::ICMP_ULE, Y,
-                        ConstantInt::get(Y->getType(), C2->udiv(C + 1)));
-  }
-
-  // (icmp ult (udiv C2, Y), C) -> (icmp ugt Y, C2/C)
-  if (Cmp.getPredicate() == ICmpInst::ICMP_ULT) {
-    assert(C != 0 && "icmp ult X, 0 should have been simplified already.");
-    return new ICmpInst(ICmpInst::ICMP_UGT, Y,
-                        ConstantInt::get(Y->getType(), C2->udiv(C)));
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp ({su}div X, Y), C.
-Instruction *InstCombiner::foldICmpDivConstant(ICmpInst &Cmp,
-                                               BinaryOperator *Div,
-                                               const APInt &C) {
-  // Fold: icmp pred ([us]div X, C2), C -> range test
-  // Fold this div into the comparison, producing a range check.
-  // Determine, based on the divide type, what the range is being
-  // checked.  If there is an overflow on the low or high side, remember
-  // it, otherwise compute the range [low, hi) bounding the new value.
-  // See: InsertRangeTest above for the kinds of replacements possible.
-  const APInt *C2;
-  if (!match(Div->getOperand(1), m_APInt(C2)))
-    return nullptr;
-
-  // FIXME: If the operand types don't match the type of the divide
-  // then don't attempt this transform. The code below doesn't have the
-  // logic to deal with a signed divide and an unsigned compare (and
-  // vice versa). This is because (x /s C2) <s C  produces different
-  // results than (x /s C2) <u C or (x /u C2) <s C or even
-  // (x /u C2) <u C.  Simply casting the operands and result won't
-  // work. :(  The if statement below tests that condition and bails
-  // if it finds it.
-  bool DivIsSigned = Div->getOpcode() == Instruction::SDiv;
-  if (!Cmp.isEquality() && DivIsSigned != Cmp.isSigned())
-    return nullptr;
-
-  // The ProdOV computation fails on divide by 0 and divide by -1. Cases with
-  // INT_MIN will also fail if the divisor is 1. Although folds of all these
-  // division-by-constant cases should be present, we can not assert that they
-  // have happened before we reach this icmp instruction.
-  if (C2->isNullValue() || C2->isOneValue() ||
-      (DivIsSigned && C2->isAllOnesValue()))
-    return nullptr;
-
-  // Compute Prod = C * C2. We are essentially solving an equation of
-  // form X / C2 = C. We solve for X by multiplying C2 and C.
-  // By solving for X, we can turn this into a range check instead of computing
-  // a divide.
-  APInt Prod = C * *C2;
-
-  // Determine if the product overflows by seeing if the product is not equal to
-  // the divide. Make sure we do the same kind of divide as in the LHS
-  // instruction that we're folding.
-  bool ProdOV = (DivIsSigned ? Prod.sdiv(*C2) : Prod.udiv(*C2)) != C;
-
-  ICmpInst::Predicate Pred = Cmp.getPredicate();
-
-  // If the division is known to be exact, then there is no remainder from the
-  // divide, so the covered range size is unit, otherwise it is the divisor.
-  APInt RangeSize = Div->isExact() ? APInt(C2->getBitWidth(), 1) : *C2;
-
-  // Figure out the interval that is being checked.  For example, a comparison
-  // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
-  // Compute this interval based on the constants involved and the signedness of
-  // the compare/divide.  This computes a half-open interval, keeping track of
-  // whether either value in the interval overflows.  After analysis each
-  // overflow variable is set to 0 if it's corresponding bound variable is valid
-  // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
-  int LoOverflow = 0, HiOverflow = 0;
-  APInt LoBound, HiBound;
-
-  if (!DivIsSigned) {  // udiv
-    // e.g. X/5 op 3  --> [15, 20)
-    LoBound = Prod;
-    HiOverflow = LoOverflow = ProdOV;
-    if (!HiOverflow) {
-      // If this is not an exact divide, then many values in the range collapse
-      // to the same result value.
-      HiOverflow = addWithOverflow(HiBound, LoBound, RangeSize, false);
-    }
-  } else if (C2->isStrictlyPositive()) { // Divisor is > 0.
-    if (C.isNullValue()) {       // (X / pos) op 0
-      // Can't overflow.  e.g.  X/2 op 0 --> [-1, 2)
-      LoBound = -(RangeSize - 1);
-      HiBound = RangeSize;
-    } else if (C.isStrictlyPositive()) {   // (X / pos) op pos
-      LoBound = Prod;     // e.g.   X/5 op 3 --> [15, 20)
-      HiOverflow = LoOverflow = ProdOV;
-      if (!HiOverflow)
-        HiOverflow = addWithOverflow(HiBound, Prod, RangeSize, true);
-    } else {                       // (X / pos) op neg
-      // e.g. X/5 op -3  --> [-15-4, -15+1) --> [-19, -14)
-      HiBound = Prod + 1;
-      LoOverflow = HiOverflow = ProdOV ? -1 : 0;
-      if (!LoOverflow) {
-        APInt DivNeg = -RangeSize;
-        LoOverflow = addWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0;
-      }
-    }
-  } else if (C2->isNegative()) { // Divisor is < 0.
-    if (Div->isExact())
-      RangeSize.negate();
-    if (C.isNullValue()) { // (X / neg) op 0
-      // e.g. X/-5 op 0  --> [-4, 5)
-      LoBound = RangeSize + 1;
-      HiBound = -RangeSize;
-      if (HiBound == *C2) {        // -INTMIN = INTMIN
-        HiOverflow = 1;            // [INTMIN+1, overflow)
-        HiBound = APInt();         // e.g. X/INTMIN = 0 --> X > INTMIN
-      }
-    } else if (C.isStrictlyPositive()) {   // (X / neg) op pos
-      // e.g. X/-5 op 3  --> [-19, -14)
-      HiBound = Prod + 1;
-      HiOverflow = LoOverflow = ProdOV ? -1 : 0;
-      if (!LoOverflow)
-        LoOverflow = addWithOverflow(LoBound, HiBound, RangeSize, true) ? -1:0;
-    } else {                       // (X / neg) op neg
-      LoBound = Prod;       // e.g. X/-5 op -3  --> [15, 20)
-      LoOverflow = HiOverflow = ProdOV;
-      if (!HiOverflow)
-        HiOverflow = subWithOverflow(HiBound, Prod, RangeSize, true);
-    }
-
-    // Dividing by a negative swaps the condition.  LT <-> GT
-    Pred = ICmpInst::getSwappedPredicate(Pred);
-  }
-
-  Value *X = Div->getOperand(0);
-  switch (Pred) {
-    default: llvm_unreachable("Unhandled icmp opcode!");
-    case ICmpInst::ICMP_EQ:
-      if (LoOverflow && HiOverflow)
-        return replaceInstUsesWith(Cmp, Builder.getFalse());
-      if (HiOverflow)
-        return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
-                            ICmpInst::ICMP_UGE, X,
-                            ConstantInt::get(Div->getType(), LoBound));
-      if (LoOverflow)
-        return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
-                            ICmpInst::ICMP_ULT, X,
-                            ConstantInt::get(Div->getType(), HiBound));
-      return replaceInstUsesWith(
-          Cmp, insertRangeTest(X, LoBound, HiBound, DivIsSigned, true));
-    case ICmpInst::ICMP_NE:
-      if (LoOverflow && HiOverflow)
-        return replaceInstUsesWith(Cmp, Builder.getTrue());
-      if (HiOverflow)
-        return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
-                            ICmpInst::ICMP_ULT, X,
-                            ConstantInt::get(Div->getType(), LoBound));
-      if (LoOverflow)
-        return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
-                            ICmpInst::ICMP_UGE, X,
-                            ConstantInt::get(Div->getType(), HiBound));
-      return replaceInstUsesWith(Cmp,
-                                 insertRangeTest(X, LoBound, HiBound,
-                                                 DivIsSigned, false));
-    case ICmpInst::ICMP_ULT:
-    case ICmpInst::ICMP_SLT:
-      if (LoOverflow == +1)   // Low bound is greater than input range.
-        return replaceInstUsesWith(Cmp, Builder.getTrue());
-      if (LoOverflow == -1)   // Low bound is less than input range.
-        return replaceInstUsesWith(Cmp, Builder.getFalse());
-      return new ICmpInst(Pred, X, ConstantInt::get(Div->getType(), LoBound));
-    case ICmpInst::ICMP_UGT:
-    case ICmpInst::ICMP_SGT:
-      if (HiOverflow == +1)       // High bound greater than input range.
-        return replaceInstUsesWith(Cmp, Builder.getFalse());
-      if (HiOverflow == -1)       // High bound less than input range.
-        return replaceInstUsesWith(Cmp, Builder.getTrue());
-      if (Pred == ICmpInst::ICMP_UGT)
-        return new ICmpInst(ICmpInst::ICMP_UGE, X,
-                            ConstantInt::get(Div->getType(), HiBound));
-      return new ICmpInst(ICmpInst::ICMP_SGE, X,
-                          ConstantInt::get(Div->getType(), HiBound));
-  }
-
-  return nullptr;
-}
-
-/// Fold icmp (sub X, Y), C.
-Instruction *InstCombiner::foldICmpSubConstant(ICmpInst &Cmp,
-                                               BinaryOperator *Sub,
-                                               const APInt &C) {
-  Value *X = Sub->getOperand(0), *Y = Sub->getOperand(1);
-  ICmpInst::Predicate Pred = Cmp.getPredicate();
-
-  // The following transforms are only worth it if the only user of the subtract
-  // is the icmp.
-  if (!Sub->hasOneUse())
-    return nullptr;
-
-  if (Sub->hasNoSignedWrap()) {
-    // (icmp sgt (sub nsw X, Y), -1) -> (icmp sge X, Y)
-    if (Pred == ICmpInst::ICMP_SGT && C.isAllOnesValue())
-      return new ICmpInst(ICmpInst::ICMP_SGE, X, Y);
-
-    // (icmp sgt (sub nsw X, Y), 0) -> (icmp sgt X, Y)
-    if (Pred == ICmpInst::ICMP_SGT && C.isNullValue())
-      return new ICmpInst(ICmpInst::ICMP_SGT, X, Y);
-
-    // (icmp slt (sub nsw X, Y), 0) -> (icmp slt X, Y)
-    if (Pred == ICmpInst::ICMP_SLT && C.isNullValue())
-      return new ICmpInst(ICmpInst::ICMP_SLT, X, Y);
-
-    // (icmp slt (sub nsw X, Y), 1) -> (icmp sle X, Y)
-    if (Pred == ICmpInst::ICMP_SLT && C.isOneValue())
-      return new ICmpInst(ICmpInst::ICMP_SLE, X, Y);
-  }
-
-  const APInt *C2;
-  if (!match(X, m_APInt(C2)))
-    return nullptr;
-
-  // C2 - Y <u C -> (Y | (C - 1)) == C2
-  //   iff (C2 & (C - 1)) == C - 1 and C is a power of 2
-  if (Pred == ICmpInst::ICMP_ULT && C.isPowerOf2() &&
-      (*C2 & (C - 1)) == (C - 1))
-    return new ICmpInst(ICmpInst::ICMP_EQ, Builder.CreateOr(Y, C - 1), X);
-
-  // C2 - Y >u C -> (Y | C) != C2
-  //   iff C2 & C == C and C + 1 is a power of 2
-  if (Pred == ICmpInst::ICMP_UGT && (C + 1).isPowerOf2() && (*C2 & C) == C)
-    return new ICmpInst(ICmpInst::ICMP_NE, Builder.CreateOr(Y, C), X);
-
-  return nullptr;
-}
-
-/// Fold icmp (add X, Y), C.
-Instruction *InstCombiner::foldICmpAddConstant(ICmpInst &Cmp,
-                                               BinaryOperator *Add,
-                                               const APInt &C) {
-  Value *Y = Add->getOperand(1);
-  const APInt *C2;
-  if (Cmp.isEquality() || !match(Y, m_APInt(C2)))
-    return nullptr;
-
-  // Fold icmp pred (add X, C2), C.
-  Value *X = Add->getOperand(0);
-  Type *Ty = Add->getType();
-  CmpInst::Predicate Pred = Cmp.getPredicate();
-
-  if (!Add->hasOneUse())
-    return nullptr;
-
-  // If the add does not wrap, we can always adjust the compare by subtracting
-  // the constants. Equality comparisons are handled elsewhere. SGE/SLE/UGE/ULE
-  // are canonicalized to SGT/SLT/UGT/ULT.
-  if ((Add->hasNoSignedWrap() &&
-       (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLT)) ||
-      (Add->hasNoUnsignedWrap() &&
-       (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_ULT))) {
-    bool Overflow;
-    APInt NewC =
-        Cmp.isSigned() ? C.ssub_ov(*C2, Overflow) : C.usub_ov(*C2, Overflow);
-    // If there is overflow, the result must be true or false.
-    // TODO: Can we assert there is no overflow because InstSimplify always
-    // handles those cases?
-    if (!Overflow)
-      // icmp Pred (add nsw X, C2), C --> icmp Pred X, (C - C2)
-      return new ICmpInst(Pred, X, ConstantInt::get(Ty, NewC));
-  }
-
-  auto CR = ConstantRange::makeExactICmpRegion(Pred, C).subtract(*C2);
-  const APInt &Upper = CR.getUpper();
-  const APInt &Lower = CR.getLower();
-  if (Cmp.isSigned()) {
-    if (Lower.isSignMask())
-      return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantInt::get(Ty, Upper));
-    if (Upper.isSignMask())
-      return new ICmpInst(ICmpInst::ICMP_SGE, X, ConstantInt::get(Ty, Lower));
-  } else {
-    if (Lower.isMinValue())
-      return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantInt::get(Ty, Upper));
-    if (Upper.isMinValue())
-      return new ICmpInst(ICmpInst::ICMP_UGE, X, ConstantInt::get(Ty, Lower));
-  }
-
-  // X+C <u C2 -> (X & -C2) == C
-  //   iff C & (C2-1) == 0
-  //       C2 is a power of 2
-  if (Pred == ICmpInst::ICMP_ULT && C.isPowerOf2() && (*C2 & (C - 1)) == 0)
-    return new ICmpInst(ICmpInst::ICMP_EQ, Builder.CreateAnd(X, -C),
-                        ConstantExpr::getNeg(cast<Constant>(Y)));
-
-  // X+C >u C2 -> (X & ~C2) != C
-  //   iff C & C2 == 0
-  //       C2+1 is a power of 2
-  if (Pred == ICmpInst::ICMP_UGT && (C + 1).isPowerOf2() && (*C2 & C) == 0)
-    return new ICmpInst(ICmpInst::ICMP_NE, Builder.CreateAnd(X, ~C),
-                        ConstantExpr::getNeg(cast<Constant>(Y)));
-
-  return nullptr;
-}
-
-bool InstCombiner::matchThreeWayIntCompare(SelectInst *SI, Value *&LHS,
-                                           Value *&RHS, ConstantInt *&Less,
-                                           ConstantInt *&Equal,
-                                           ConstantInt *&Greater) {
-  // TODO: Generalize this to work with other comparison idioms or ensure
-  // they get canonicalized into this form.
-
-  // select i1 (a == b), i32 Equal, i32 (select i1 (a < b), i32 Less, i32
-  // Greater), where Equal, Less and Greater are placeholders for any three
-  // constants.
-  ICmpInst::Predicate PredA, PredB;
-  if (match(SI->getTrueValue(), m_ConstantInt(Equal)) &&
-      match(SI->getCondition(), m_ICmp(PredA, m_Value(LHS), m_Value(RHS))) &&
-      PredA == ICmpInst::ICMP_EQ &&
-      match(SI->getFalseValue(),
-            m_Select(m_ICmp(PredB, m_Specific(LHS), m_Specific(RHS)),
-                     m_ConstantInt(Less), m_ConstantInt(Greater))) &&
-      PredB == ICmpInst::ICMP_SLT) {
-    return true;
-  }
-  return false;
-}
-
-Instruction *InstCombiner::foldICmpSelectConstant(ICmpInst &Cmp,
-                                                  SelectInst *Select,
-                                                  ConstantInt *C) {
-
-  assert(C && "Cmp RHS should be a constant int!");
-  // If we're testing a constant value against the result of a three way
-  // comparison, the result can be expressed directly in terms of the
-  // original values being compared.  Note: We could possibly be more
-  // aggressive here and remove the hasOneUse test. The original select is
-  // really likely to simplify or sink when we remove a test of the result.
-  Value *OrigLHS, *OrigRHS;
-  ConstantInt *C1LessThan, *C2Equal, *C3GreaterThan;
-  if (Cmp.hasOneUse() &&
-      matchThreeWayIntCompare(Select, OrigLHS, OrigRHS, C1LessThan, C2Equal,
-                              C3GreaterThan)) {
-    assert(C1LessThan && C2Equal && C3GreaterThan);
-
-    bool TrueWhenLessThan =
-        ConstantExpr::getCompare(Cmp.getPredicate(), C1LessThan, C)
-            ->isAllOnesValue();
-    bool TrueWhenEqual =
-        ConstantExpr::getCompare(Cmp.getPredicate(), C2Equal, C)
-            ->isAllOnesValue();
-    bool TrueWhenGreaterThan =
-        ConstantExpr::getCompare(Cmp.getPredicate(), C3GreaterThan, C)
-            ->isAllOnesValue();
-
-    // This generates the new instruction that will replace the original Cmp
-    // Instruction. Instead of enumerating the various combinations when
-    // TrueWhenLessThan, TrueWhenEqual and TrueWhenGreaterThan are true versus
-    // false, we rely on chaining of ORs and future passes of InstCombine to
-    // simplify the OR further (i.e. a s< b || a == b becomes a s<= b).
-
-    // When none of the three constants satisfy the predicate for the RHS (C),
-    // the entire original Cmp can be simplified to a false.
-    Value *Cond = Builder.getFalse();
-    if (TrueWhenLessThan)
-      Cond = Builder.CreateOr(Cond, Builder.CreateICmp(ICmpInst::ICMP_SLT, OrigLHS, OrigRHS));
-    if (TrueWhenEqual)
-      Cond = Builder.CreateOr(Cond, Builder.CreateICmp(ICmpInst::ICMP_EQ, OrigLHS, OrigRHS));
-    if (TrueWhenGreaterThan)
-      Cond = Builder.CreateOr(Cond, Builder.CreateICmp(ICmpInst::ICMP_SGT, OrigLHS, OrigRHS));
-
-    return replaceInstUsesWith(Cmp, Cond);
-  }
-  return nullptr;
-}
-
-Instruction *InstCombiner::foldICmpBitCastConstant(ICmpInst &Cmp,
-                                                   BitCastInst *Bitcast,
-                                                   const APInt &C) {
-  // Folding: icmp <pred> iN X, C
-  //  where X = bitcast <M x iK> (shufflevector <M x iK> %vec, undef, SC)) to iN
-  //    and C is a splat of a K-bit pattern
-  //    and SC is a constant vector = <C', C', C', ..., C'>
-  // Into:
-  //   %E = extractelement <M x iK> %vec, i32 C'
-  //   icmp <pred> iK %E, trunc(C)
-  if (!Bitcast->getType()->isIntegerTy() ||
-      !Bitcast->getSrcTy()->isIntOrIntVectorTy())
-    return nullptr;
-
-  Value *BCIOp = Bitcast->getOperand(0);
-  Value *Vec = nullptr;     // 1st vector arg of the shufflevector
-  Constant *Mask = nullptr; // Mask arg of the shufflevector
-  if (match(BCIOp,
-            m_ShuffleVector(m_Value(Vec), m_Undef(), m_Constant(Mask)))) {
-    // Check whether every element of Mask is the same constant
-    if (auto *Elem = dyn_cast_or_null<ConstantInt>(Mask->getSplatValue())) {
-      auto *VecTy = cast<VectorType>(BCIOp->getType());
-      auto *EltTy = cast<IntegerType>(VecTy->getElementType());
-      auto Pred = Cmp.getPredicate();
-      if (C.isSplat(EltTy->getBitWidth())) {
-        // Fold the icmp based on the value of C
-        // If C is M copies of an iK sized bit pattern,
-        // then:
-        //   =>  %E = extractelement <N x iK> %vec, i32 Elem
-        //       icmp <pred> iK %SplatVal, <pattern>
-        Value *Extract = Builder.CreateExtractElement(Vec, Elem);
-        Value *NewC = ConstantInt::get(EltTy, C.trunc(EltTy->getBitWidth()));
-        return new ICmpInst(Pred, Extract, NewC);
-      }
-    }
-  }
-  return nullptr;
-}
-
-/// Try to fold integer comparisons with a constant operand: icmp Pred X, C
-/// where X is some kind of instruction.
-Instruction *InstCombiner::foldICmpInstWithConstant(ICmpInst &Cmp) {
-  const APInt *C;
-  if (!match(Cmp.getOperand(1), m_APInt(C)))
-    return nullptr;
-
-  if (auto *BO = dyn_cast<BinaryOperator>(Cmp.getOperand(0))) {
-    switch (BO->getOpcode()) {
-    case Instruction::Xor:
-      if (Instruction *I = foldICmpXorConstant(Cmp, BO, *C))
-        return I;
-      break;
-    case Instruction::And:
-      if (Instruction *I = foldICmpAndConstant(Cmp, BO, *C))
-        return I;
-      break;
-    case Instruction::Or:
-      if (Instruction *I = foldICmpOrConstant(Cmp, BO, *C))
-        return I;
-      break;
-    case Instruction::Mul:
-      if (Instruction *I = foldICmpMulConstant(Cmp, BO, *C))
-        return I;
-      break;
-    case Instruction::Shl:
-      if (Instruction *I = foldICmpShlConstant(Cmp, BO, *C))
-        return I;
-      break;
-    case Instruction::LShr:
-    case Instruction::AShr:
-      if (Instruction *I = foldICmpShrConstant(Cmp, BO, *C))
-        return I;
-      break;
-    case Instruction::UDiv:
-      if (Instruction *I = foldICmpUDivConstant(Cmp, BO, *C))
-        return I;
-      LLVM_FALLTHROUGH;
-    case Instruction::SDiv:
-      if (Instruction *I = foldICmpDivConstant(Cmp, BO, *C))
-        return I;
-      break;
-    case Instruction::Sub:
-      if (Instruction *I = foldICmpSubConstant(Cmp, BO, *C))
-        return I;
-      break;
-    case Instruction::Add:
-      if (Instruction *I = foldICmpAddConstant(Cmp, BO, *C))
-        return I;
-      break;
-    default:
-      break;
-    }
-    // TODO: These folds could be refactored to be part of the above calls.
-    if (Instruction *I = foldICmpBinOpEqualityWithConstant(Cmp, BO, *C))
-      return I;
-  }
-
-  // Match against CmpInst LHS being instructions other than binary operators.
-
-  if (auto *SI = dyn_cast<SelectInst>(Cmp.getOperand(0))) {
-    // For now, we only support constant integers while folding the
-    // ICMP(SELECT)) pattern. We can extend this to support vector of integers
-    // similar to the cases handled by binary ops above.
-    if (ConstantInt *ConstRHS = dyn_cast<ConstantInt>(Cmp.getOperand(1)))
-      if (Instruction *I = foldICmpSelectConstant(Cmp, SI, ConstRHS))
-        return I;
-  }
-
-  if (auto *TI = dyn_cast<TruncInst>(Cmp.getOperand(0))) {
-    if (Instruction *I = foldICmpTruncConstant(Cmp, TI, *C))
-      return I;
-  }
-
-  if (auto *BCI = dyn_cast<BitCastInst>(Cmp.getOperand(0))) {
-    if (Instruction *I = foldICmpBitCastConstant(Cmp, BCI, *C))
-      return I;
-  }
-
-  if (Instruction *I = foldICmpIntrinsicWithConstant(Cmp, *C))
-    return I;
-
-  return nullptr;
-}
-
-/// Fold an icmp equality instruction with binary operator LHS and constant RHS:
-/// icmp eq/ne BO, C.
-Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(ICmpInst &Cmp,
-                                                             BinaryOperator *BO,
-                                                             const APInt &C) {
-  // TODO: Some of these folds could work with arbitrary constants, but this
-  // function is limited to scalar and vector splat constants.
-  if (!Cmp.isEquality())
-    return nullptr;
-
-  ICmpInst::Predicate Pred = Cmp.getPredicate();
-  bool isICMP_NE = Pred == ICmpInst::ICMP_NE;
-  Constant *RHS = cast<Constant>(Cmp.getOperand(1));
-  Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
-
-  switch (BO->getOpcode()) {
-  case Instruction::SRem:
-    // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
-    if (C.isNullValue() && BO->hasOneUse()) {
-      const APInt *BOC;
-      if (match(BOp1, m_APInt(BOC)) && BOC->sgt(1) && BOC->isPowerOf2()) {
-        Value *NewRem = Builder.CreateURem(BOp0, BOp1, BO->getName());
-        return new ICmpInst(Pred, NewRem,
-                            Constant::getNullValue(BO->getType()));
-      }
-    }
-    break;
-  case Instruction::Add: {
-    // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
-    const APInt *BOC;
-    if (match(BOp1, m_APInt(BOC))) {
-      if (BO->hasOneUse()) {
-        Constant *SubC = ConstantExpr::getSub(RHS, cast<Constant>(BOp1));
-        return new ICmpInst(Pred, BOp0, SubC);
-      }
-    } else if (C.isNullValue()) {
-      // Replace ((add A, B) != 0) with (A != -B) if A or B is
-      // efficiently invertible, or if the add has just this one use.
-      if (Value *NegVal = dyn_castNegVal(BOp1))
-        return new ICmpInst(Pred, BOp0, NegVal);
-      if (Value *NegVal = dyn_castNegVal(BOp0))
-        return new ICmpInst(Pred, NegVal, BOp1);
-      if (BO->hasOneUse()) {
-        Value *Neg = Builder.CreateNeg(BOp1);
-        Neg->takeName(BO);
-        return new ICmpInst(Pred, BOp0, Neg);
-      }
-    }
-    break;
-  }
-  case Instruction::Xor:
-    if (BO->hasOneUse()) {
-      if (Constant *BOC = dyn_cast<Constant>(BOp1)) {
-        // For the xor case, we can xor two constants together, eliminating
-        // the explicit xor.
-        return new ICmpInst(Pred, BOp0, ConstantExpr::getXor(RHS, BOC));
-      } else if (C.isNullValue()) {
-        // Replace ((xor A, B) != 0) with (A != B)
-        return new ICmpInst(Pred, BOp0, BOp1);
-      }
-    }
-    break;
-  case Instruction::Sub:
-    if (BO->hasOneUse()) {
-      const APInt *BOC;
-      if (match(BOp0, m_APInt(BOC))) {
-        // Replace ((sub BOC, B) != C) with (B != BOC-C).
-        Constant *SubC = ConstantExpr::getSub(cast<Constant>(BOp0), RHS);
-        return new ICmpInst(Pred, BOp1, SubC);
-      } else if (C.isNullValue()) {
-        // Replace ((sub A, B) != 0) with (A != B).
-        return new ICmpInst(Pred, BOp0, BOp1);
-      }
-    }
-    break;
-  case Instruction::Or: {
-    const APInt *BOC;
-    if (match(BOp1, m_APInt(BOC)) && BO->hasOneUse() && RHS->isAllOnesValue()) {
-      // Comparing if all bits outside of a constant mask are set?
-      // Replace (X | C) == -1 with (X & ~C) == ~C.
-      // This removes the -1 constant.
-      Constant *NotBOC = ConstantExpr::getNot(cast<Constant>(BOp1));
-      Value *And = Builder.CreateAnd(BOp0, NotBOC);
-      return new ICmpInst(Pred, And, NotBOC);
-    }
-    break;
-  }
-  case Instruction::And: {
-    const APInt *BOC;
-    if (match(BOp1, m_APInt(BOC))) {
-      // If we have ((X & C) == C), turn it into ((X & C) != 0).
-      if (C == *BOC && C.isPowerOf2())
-        return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,
-                            BO, Constant::getNullValue(RHS->getType()));
-
-      // Don't perform the following transforms if the AND has multiple uses
-      if (!BO->hasOneUse())
-        break;
-
-      // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
-      if (BOC->isSignMask()) {
-        Constant *Zero = Constant::getNullValue(BOp0->getType());
-        auto NewPred = isICMP_NE ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
-        return new ICmpInst(NewPred, BOp0, Zero);
-      }
-
-      // ((X & ~7) == 0) --> X < 8
-      if (C.isNullValue() && (~(*BOC) + 1).isPowerOf2()) {
-        Constant *NegBOC = ConstantExpr::getNeg(cast<Constant>(BOp1));
-        auto NewPred = isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
-        return new ICmpInst(NewPred, BOp0, NegBOC);
-      }
-    }
-    break;
-  }
-  case Instruction::Mul:
-    if (C.isNullValue() && BO->hasNoSignedWrap()) {
-      const APInt *BOC;
-      if (match(BOp1, m_APInt(BOC)) && !BOC->isNullValue()) {
-        // The trivial case (mul X, 0) is handled by InstSimplify.
-        // General case : (mul X, C) != 0 iff X != 0
-        //                (mul X, C) == 0 iff X == 0
-        return new ICmpInst(Pred, BOp0, Constant::getNullValue(RHS->getType()));
-      }
-    }
-    break;
-  case Instruction::UDiv:
-    if (C.isNullValue()) {
-      // (icmp eq/ne (udiv A, B), 0) -> (icmp ugt/ule i32 B, A)
-      auto NewPred = isICMP_NE ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_UGT;
-      return new ICmpInst(NewPred, BOp1, BOp0);
-    }
-    break;
-  default:
-    break;
-  }
-  return nullptr;
-}
-
-/// Fold an icmp with LLVM intrinsic and constant operand: icmp Pred II, C.
-Instruction *InstCombiner::foldICmpIntrinsicWithConstant(ICmpInst &Cmp,
-                                                         const APInt &C) {
-  IntrinsicInst *II = dyn_cast<IntrinsicInst>(Cmp.getOperand(0));
-  if (!II || !Cmp.isEquality())
-    return nullptr;
-
-  // Handle icmp {eq|ne} <intrinsic>, Constant.
-  Type *Ty = II->getType();
-  unsigned BitWidth = C.getBitWidth();
-  switch (II->getIntrinsicID()) {
-  case Intrinsic::bswap:
-    Worklist.Add(II);
-    Cmp.setOperand(0, II->getArgOperand(0));
-    Cmp.setOperand(1, ConstantInt::get(Ty, C.byteSwap()));
-    return &Cmp;
-
-  case Intrinsic::ctlz:
-  case Intrinsic::cttz: {
-    // ctz(A) == bitwidth(A)  ->  A == 0 and likewise for !=
-    if (C == BitWidth) {
-      Worklist.Add(II);
-      Cmp.setOperand(0, II->getArgOperand(0));
-      Cmp.setOperand(1, ConstantInt::getNullValue(Ty));
-      return &Cmp;
-    }
-
-    // ctz(A) == C -> A & Mask1 == Mask2, where Mask2 only has bit C set
-    // and Mask1 has bits 0..C+1 set. Similar for ctl, but for high bits.
-    // Limit to one use to ensure we don't increase instruction count.
-    unsigned Num = C.getLimitedValue(BitWidth);
-    if (Num != BitWidth && II->hasOneUse()) {
-      bool IsTrailing = II->getIntrinsicID() == Intrinsic::cttz;
-      APInt Mask1 = IsTrailing ? APInt::getLowBitsSet(BitWidth, Num + 1)
-                               : APInt::getHighBitsSet(BitWidth, Num + 1);
-      APInt Mask2 = IsTrailing
-        ? APInt::getOneBitSet(BitWidth, Num)
-        : APInt::getOneBitSet(BitWidth, BitWidth - Num - 1);
-      Cmp.setOperand(0, Builder.CreateAnd(II->getArgOperand(0), Mask1));
-      Cmp.setOperand(1, ConstantInt::get(Ty, Mask2));
-      Worklist.Add(II);
-      return &Cmp;
-    }
-    break;
-  }
-
-  case Intrinsic::ctpop: {
-    // popcount(A) == 0  ->  A == 0 and likewise for !=
-    // popcount(A) == bitwidth(A)  ->  A == -1 and likewise for !=
-    bool IsZero = C.isNullValue();
-    if (IsZero || C == BitWidth) {
-      Worklist.Add(II);
-      Cmp.setOperand(0, II->getArgOperand(0));
-      auto *NewOp =
-          IsZero ? Constant::getNullValue(Ty) : Constant::getAllOnesValue(Ty);
-      Cmp.setOperand(1, NewOp);
-      return &Cmp;
-    }
-    break;
-  }
-  default:
-    break;
-  }
-
-  return nullptr;
-}
-
-/// Handle icmp with constant (but not simple integer constant) RHS.
-Instruction *InstCombiner::foldICmpInstWithConstantNotInt(ICmpInst &I) {
-  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-  Constant *RHSC = dyn_cast<Constant>(Op1);
-  Instruction *LHSI = dyn_cast<Instruction>(Op0);
-  if (!RHSC || !LHSI)
-    return nullptr;
-
-  switch (LHSI->getOpcode()) {
-  case Instruction::GetElementPtr:
-    // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
-    if (RHSC->isNullValue() &&
-        cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices())
-      return new ICmpInst(
-          I.getPredicate(), LHSI->getOperand(0),
-          Constant::getNullValue(LHSI->getOperand(0)->getType()));
-    break;
-  case Instruction::PHI:
-    // Only fold icmp into the PHI if the phi and icmp are in the same
-    // block.  If in the same block, we're encouraging jump threading.  If
-    // not, we are just pessimizing the code by making an i1 phi.
-    if (LHSI->getParent() == I.getParent())
-      if (Instruction *NV = foldOpIntoPhi(I, cast<PHINode>(LHSI)))
-        return NV;
-    break;
-  case Instruction::Select: {
-    // If either operand of the select is a constant, we can fold the
-    // comparison into the select arms, which will cause one to be
-    // constant folded and the select turned into a bitwise or.
-    Value *Op1 = nullptr, *Op2 = nullptr;
-    ConstantInt *CI = nullptr;
-    if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
-      Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
-      CI = dyn_cast<ConstantInt>(Op1);
-    }
-    if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
-      Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
-      CI = dyn_cast<ConstantInt>(Op2);
-    }
-
-    // We only want to perform this transformation if it will not lead to
-    // additional code. This is true if either both sides of the select
-    // fold to a constant (in which case the icmp is replaced with a select
-    // which will usually simplify) or this is the only user of the
-    // select (in which case we are trading a select+icmp for a simpler
-    // select+icmp) or all uses of the select can be replaced based on
-    // dominance information ("Global cases").
-    bool Transform = false;
-    if (Op1 && Op2)
-      Transform = true;
-    else if (Op1 || Op2) {
-      // Local case
-      if (LHSI->hasOneUse())
-        Transform = true;
-      // Global cases
-      else if (CI && !CI->isZero())
-        // When Op1 is constant try replacing select with second operand.
-        // Otherwise Op2 is constant and try replacing select with first
-        // operand.
-        Transform =
-            replacedSelectWithOperand(cast<SelectInst>(LHSI), &I, Op1 ? 2 : 1);
-    }
-    if (Transform) {
-      if (!Op1)
-        Op1 = Builder.CreateICmp(I.getPredicate(), LHSI->getOperand(1), RHSC,
-                                 I.getName());
-      if (!Op2)
-        Op2 = Builder.CreateICmp(I.getPredicate(), LHSI->getOperand(2), RHSC,
-                                 I.getName());
-      return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
-    }
-    break;
-  }
-  case Instruction::IntToPtr:
-    // icmp pred inttoptr(X), null -> icmp pred X, 0
-    if (RHSC->isNullValue() &&
-        DL.getIntPtrType(RHSC->getType()) == LHSI->getOperand(0)->getType())
-      return new ICmpInst(
-          I.getPredicate(), LHSI->getOperand(0),
-          Constant::getNullValue(LHSI->getOperand(0)->getType()));
-    break;
-
-  case Instruction::Load:
-    // Try to optimize things like "A[i] > 4" to index computations.
-    if (GetElementPtrInst *GEP =
-            dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
-      if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
-        if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
-            !cast<LoadInst>(LHSI)->isVolatile())
-          if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, I))
-            return Res;
-    }
-    break;
-  }
-
-  return nullptr;
-}
-
-/// Some comparisons can be simplified.
-/// In this case, we are looking for comparisons that look like
-/// a check for a lossy truncation.
-/// Folds:
-///   icmp SrcPred (x & Mask), x    to    icmp DstPred x, Mask
-/// Where Mask is some pattern that produces all-ones in low bits:
-///    (-1 >> y)
-///    ((-1 << y) >> y)     <- non-canonical, has extra uses
-///   ~(-1 << y)
-///    ((1 << y) + (-1))    <- non-canonical, has extra uses
-/// The Mask can be a constant, too.
-/// For some predicates, the operands are commutative.
-/// For others, x can only be on a specific side.
-static Value *foldICmpWithLowBitMaskedVal(ICmpInst &I,
-                                          InstCombiner::BuilderTy &Builder) {
-  ICmpInst::Predicate SrcPred;
-  Value *X, *M, *Y;
-  auto m_VariableMask = m_CombineOr(
-      m_CombineOr(m_Not(m_Shl(m_AllOnes(), m_Value())),
-                  m_Add(m_Shl(m_One(), m_Value()), m_AllOnes())),
-      m_CombineOr(m_LShr(m_AllOnes(), m_Value()),
-                  m_LShr(m_Shl(m_AllOnes(), m_Value(Y)), m_Deferred(Y))));
-  auto m_Mask = m_CombineOr(m_VariableMask, m_LowBitMask());
-  if (!match(&I, m_c_ICmp(SrcPred,
-                          m_c_And(m_CombineAnd(m_Mask, m_Value(M)), m_Value(X)),
-                          m_Deferred(X))))
-    return nullptr;
-
-  ICmpInst::Predicate DstPred;
-  switch (SrcPred) {
-  case ICmpInst::Predicate::ICMP_EQ:
-    //  x & (-1 >> y) == x    ->    x u<= (-1 >> y)
-    DstPred = ICmpInst::Predicate::ICMP_ULE;
-    break;
-  case ICmpInst::Predicate::ICMP_NE:
-    //  x & (-1 >> y) != x    ->    x u> (-1 >> y)
-    DstPred = ICmpInst::Predicate::ICMP_UGT;
-    break;
-  case ICmpInst::Predicate::ICMP_UGT:
-    //  x u> x & (-1 >> y)    ->    x u> (-1 >> y)
-    assert(X == I.getOperand(0) && "instsimplify took care of commut. variant");
-    DstPred = ICmpInst::Predicate::ICMP_UGT;
-    break;
-  case ICmpInst::Predicate::ICMP_UGE:
-    //  x & (-1 >> y) u>= x    ->    x u<= (-1 >> y)
-    assert(X == I.getOperand(1) && "instsimplify took care of commut. variant");
-    DstPred = ICmpInst::Predicate::ICMP_ULE;
-    break;
-  case ICmpInst::Predicate::ICMP_ULT:
-    //  x & (-1 >> y) u< x    ->    x u> (-1 >> y)
-    assert(X == I.getOperand(1) && "instsimplify took care of commut. variant");
-    DstPred = ICmpInst::Predicate::ICMP_UGT;
-    break;
-  case ICmpInst::Predicate::ICMP_ULE:
-    //  x u<= x & (-1 >> y)    ->    x u<= (-1 >> y)
-    assert(X == I.getOperand(0) && "instsimplify took care of commut. variant");
-    DstPred = ICmpInst::Predicate::ICMP_ULE;
-    break;
-  case ICmpInst::Predicate::ICMP_SGT:
-    //  x s> x & (-1 >> y)    ->    x s> (-1 >> y)
-    if (X != I.getOperand(0)) // X must be on LHS of comparison!
-      return nullptr;         // Ignore the other case.
-    DstPred = ICmpInst::Predicate::ICMP_SGT;
-    break;
-  case ICmpInst::Predicate::ICMP_SGE:
-    //  x & (-1 >> y) s>= x    ->    x s<= (-1 >> y)
-    if (X != I.getOperand(1)) // X must be on RHS of comparison!
-      return nullptr;         // Ignore the other case.
-    if (!match(M, m_Constant())) // Can not do this fold with non-constant.
-      return nullptr;
-    if (!match(M, m_NonNegative())) // Must not have any -1 vector elements.
-      return nullptr;
-    DstPred = ICmpInst::Predicate::ICMP_SLE;
-    break;
-  case ICmpInst::Predicate::ICMP_SLT:
-    //  x & (-1 >> y) s< x    ->    x s> (-1 >> y)
-    if (X != I.getOperand(1)) // X must be on RHS of comparison!
-      return nullptr;         // Ignore the other case.
-    if (!match(M, m_Constant())) // Can not do this fold with non-constant.
-      return nullptr;
-    if (!match(M, m_NonNegative())) // Must not have any -1 vector elements.
-      return nullptr;
-    DstPred = ICmpInst::Predicate::ICMP_SGT;
-    break;
-  case ICmpInst::Predicate::ICMP_SLE:
-    //  x s<= x & (-1 >> y)    ->    x s<= (-1 >> y)
-    if (X != I.getOperand(0)) // X must be on LHS of comparison!
-      return nullptr;         // Ignore the other case.
-    DstPred = ICmpInst::Predicate::ICMP_SLE;
-    break;
-  default:
-    llvm_unreachable("All possible folds are handled.");
-  }
-
-  return Builder.CreateICmp(DstPred, X, M);
-}
-
-/// Some comparisons can be simplified.
-/// In this case, we are looking for comparisons that look like
-/// a check for a lossy signed truncation.
-/// Folds:   (MaskedBits is a constant.)
-///   ((%x << MaskedBits) a>> MaskedBits) SrcPred %x
-/// Into:
-///   (add %x, (1 << (KeptBits-1))) DstPred (1 << KeptBits)
-/// Where  KeptBits = bitwidth(%x) - MaskedBits
-static Value *
-foldICmpWithTruncSignExtendedVal(ICmpInst &I,
-                                 InstCombiner::BuilderTy &Builder) {
-  ICmpInst::Predicate SrcPred;
-  Value *X;
-  const APInt *C0, *C1; // FIXME: non-splats, potentially with undef.
-  // We are ok with 'shl' having multiple uses, but 'ashr' must be one-use.
-  if (!match(&I, m_c_ICmp(SrcPred,
-                          m_OneUse(m_AShr(m_Shl(m_Value(X), m_APInt(C0)),
-                                          m_APInt(C1))),
-                          m_Deferred(X))))
-    return nullptr;
-
-  // Potential handling of non-splats: for each element:
-  //  * if both are undef, replace with constant 0.
-  //    Because (1<<0) is OK and is 1, and ((1<<0)>>1) is also OK and is 0.
-  //  * if both are not undef, and are different, bailout.
-  //  * else, only one is undef, then pick the non-undef one.
-
-  // The shift amount must be equal.
-  if (*C0 != *C1)
-    return nullptr;
-  const APInt &MaskedBits = *C0;
-  assert(MaskedBits != 0 && "shift by zero should be folded away already.");
-
-  ICmpInst::Predicate DstPred;
-  switch (SrcPred) {
-  case ICmpInst::Predicate::ICMP_EQ:
-    // ((%x << MaskedBits) a>> MaskedBits) == %x
-    //   =>
-    // (add %x, (1 << (KeptBits-1))) u< (1 << KeptBits)
-    DstPred = ICmpInst::Predicate::ICMP_ULT;
-    break;
-  case ICmpInst::Predicate::ICMP_NE:
-    // ((%x << MaskedBits) a>> MaskedBits) != %x
-    //   =>
-    // (add %x, (1 << (KeptBits-1))) u>= (1 << KeptBits)
-    DstPred = ICmpInst::Predicate::ICMP_UGE;
-    break;
-  // FIXME: are more folds possible?
-  default:
-    return nullptr;
-  }
-
-  auto *XType = X->getType();
-  const unsigned XBitWidth = XType->getScalarSizeInBits();
-  const APInt BitWidth = APInt(XBitWidth, XBitWidth);
-  assert(BitWidth.ugt(MaskedBits) && "shifts should leave some bits untouched");
-
-  // KeptBits = bitwidth(%x) - MaskedBits
-  const APInt KeptBits = BitWidth - MaskedBits;
-  assert(KeptBits.ugt(0) && KeptBits.ult(BitWidth) && "unreachable");
-  // ICmpCst = (1 << KeptBits)
-  const APInt ICmpCst = APInt(XBitWidth, 1).shl(KeptBits);
-  assert(ICmpCst.isPowerOf2());
-  // AddCst = (1 << (KeptBits-1))
-  const APInt AddCst = ICmpCst.lshr(1);
-  assert(AddCst.ult(ICmpCst) && AddCst.isPowerOf2());
-
-  // T0 = add %x, AddCst
-  Value *T0 = Builder.CreateAdd(X, ConstantInt::get(XType, AddCst));
-  // T1 = T0 DstPred ICmpCst
-  Value *T1 = Builder.CreateICmp(DstPred, T0, ConstantInt::get(XType, ICmpCst));
-
-  return T1;
-}
-
-/// Try to fold icmp (binop), X or icmp X, (binop).
-/// TODO: A large part of this logic is duplicated in InstSimplify's
-/// simplifyICmpWithBinOp(). We should be able to share that and avoid the code
-/// duplication.
-Instruction *InstCombiner::foldICmpBinOp(ICmpInst &I) {
-  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-
-  // Special logic for binary operators.
-  BinaryOperator *BO0 = dyn_cast<BinaryOperator>(Op0);
-  BinaryOperator *BO1 = dyn_cast<BinaryOperator>(Op1);
-  if (!BO0 && !BO1)
-    return nullptr;
-
-  const CmpInst::Predicate Pred = I.getPredicate();
-  Value *X;
-
-  // Convert add-with-unsigned-overflow comparisons into a 'not' with compare.
-  // (Op1 + X) <u Op1 --> ~Op1 <u X
-  // Op0 >u (Op0 + X) --> X >u ~Op0
-  if (match(Op0, m_OneUse(m_c_Add(m_Specific(Op1), m_Value(X)))) &&
-      Pred == ICmpInst::ICMP_ULT)
-    return new ICmpInst(Pred, Builder.CreateNot(Op1), X);
-  if (match(Op1, m_OneUse(m_c_Add(m_Specific(Op0), m_Value(X)))) &&
-      Pred == ICmpInst::ICMP_UGT)
-    return new ICmpInst(Pred, X, Builder.CreateNot(Op0));
-
-  bool NoOp0WrapProblem = false, NoOp1WrapProblem = false;
-  if (BO0 && isa<OverflowingBinaryOperator>(BO0))
-    NoOp0WrapProblem =
-        ICmpInst::isEquality(Pred) ||
-        (CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) ||
-        (CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap());
-  if (BO1 && isa<OverflowingBinaryOperator>(BO1))
-    NoOp1WrapProblem =
-        ICmpInst::isEquality(Pred) ||
-        (CmpInst::isUnsigned(Pred) && BO1->hasNoUnsignedWrap()) ||
-        (CmpInst::isSigned(Pred) && BO1->hasNoSignedWrap());
-
-  // Analyze the case when either Op0 or Op1 is an add instruction.
-  // Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null).
-  Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
-  if (BO0 && BO0->getOpcode() == Instruction::Add) {
-    A = BO0->getOperand(0);
-    B = BO0->getOperand(1);
-  }
-  if (BO1 && BO1->getOpcode() == Instruction::Add) {
-    C = BO1->getOperand(0);
-    D = BO1->getOperand(1);
-  }
-
-  // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
-  if ((A == Op1 || B == Op1) && NoOp0WrapProblem)
-    return new ICmpInst(Pred, A == Op1 ? B : A,
-                        Constant::getNullValue(Op1->getType()));
-
-  // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
-  if ((C == Op0 || D == Op0) && NoOp1WrapProblem)
-    return new ICmpInst(Pred, Constant::getNullValue(Op0->getType()),
-                        C == Op0 ? D : C);
-
-  // icmp (X+Y), (X+Z) -> icmp Y, Z for equalities or if there is no overflow.
-  if (A && C && (A == C || A == D || B == C || B == D) && NoOp0WrapProblem &&
-      NoOp1WrapProblem &&
-      // Try not to increase register pressure.
-      BO0->hasOneUse() && BO1->hasOneUse()) {
-    // Determine Y and Z in the form icmp (X+Y), (X+Z).
-    Value *Y, *Z;
-    if (A == C) {
-      // C + B == C + D  ->  B == D
-      Y = B;
-      Z = D;
-    } else if (A == D) {
-      // D + B == C + D  ->  B == C
-      Y = B;
-      Z = C;
-    } else if (B == C) {
-      // A + C == C + D  ->  A == D
-      Y = A;
-      Z = D;
-    } else {
-      assert(B == D);
-      // A + D == C + D  ->  A == C
-      Y = A;
-      Z = C;
-    }
-    return new ICmpInst(Pred, Y, Z);
-  }
-
-  // icmp slt (X + -1), Y -> icmp sle X, Y
-  if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLT &&
-      match(B, m_AllOnes()))
-    return new ICmpInst(CmpInst::ICMP_SLE, A, Op1);
-
-  // icmp sge (X + -1), Y -> icmp sgt X, Y
-  if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGE &&
-      match(B, m_AllOnes()))
-    return new ICmpInst(CmpInst::ICMP_SGT, A, Op1);
-
-  // icmp sle (X + 1), Y -> icmp slt X, Y
-  if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLE && match(B, m_One()))
-    return new ICmpInst(CmpInst::ICMP_SLT, A, Op1);
-
-  // icmp sgt (X + 1), Y -> icmp sge X, Y
-  if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGT && match(B, m_One()))
-    return new ICmpInst(CmpInst::ICMP_SGE, A, Op1);
-
-  // icmp sgt X, (Y + -1) -> icmp sge X, Y
-  if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_SGT &&
-      match(D, m_AllOnes()))
-    return new ICmpInst(CmpInst::ICMP_SGE, Op0, C);
-
-  // icmp sle X, (Y + -1) -> icmp slt X, Y
-  if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_SLE &&
-      match(D, m_AllOnes()))
-    return new ICmpInst(CmpInst::ICMP_SLT, Op0, C);
-
-  // icmp sge X, (Y + 1) -> icmp sgt X, Y
-  if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_SGE && match(D, m_One()))
-    return new ICmpInst(CmpInst::ICMP_SGT, Op0, C);
-
-  // icmp slt X, (Y + 1) -> icmp sle X, Y
-  if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_SLT && match(D, m_One()))
-    return new ICmpInst(CmpInst::ICMP_SLE, Op0, C);
-
-  // TODO: The subtraction-related identities shown below also hold, but
-  // canonicalization from (X -nuw 1) to (X + -1) means that the combinations
-  // wouldn't happen even if they were implemented.
-  //
-  // icmp ult (X - 1), Y -> icmp ule X, Y
-  // icmp uge (X - 1), Y -> icmp ugt X, Y
-  // icmp ugt X, (Y - 1) -> icmp uge X, Y
-  // icmp ule X, (Y - 1) -> icmp ult X, Y
-
-  // icmp ule (X + 1), Y -> icmp ult X, Y
-  if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_ULE && match(B, m_One()))
-    return new ICmpInst(CmpInst::ICMP_ULT, A, Op1);
-
-  // icmp ugt (X + 1), Y -> icmp uge X, Y
-  if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_UGT && match(B, m_One()))
-    return new ICmpInst(CmpInst::ICMP_UGE, A, Op1);
-
-  // icmp uge X, (Y + 1) -> icmp ugt X, Y
-  if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_UGE && match(D, m_One()))
-    return new ICmpInst(CmpInst::ICMP_UGT, Op0, C);
-
-  // icmp ult X, (Y + 1) -> icmp ule X, Y
-  if (C && NoOp1WrapProblem && Pred == CmpInst::ICMP_ULT && match(D, m_One()))
-    return new ICmpInst(CmpInst::ICMP_ULE, Op0, C);
-
-  // if C1 has greater magnitude than C2:
-  //  icmp (X + C1), (Y + C2) -> icmp (X + C3), Y
-  //  s.t. C3 = C1 - C2
-  //
-  // if C2 has greater magnitude than C1:
-  //  icmp (X + C1), (Y + C2) -> icmp X, (Y + C3)
-  //  s.t. C3 = C2 - C1
-  if (A && C && NoOp0WrapProblem && NoOp1WrapProblem &&
-      (BO0->hasOneUse() || BO1->hasOneUse()) && !I.isUnsigned())
-    if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
-      if (ConstantInt *C2 = dyn_cast<ConstantInt>(D)) {
-        const APInt &AP1 = C1->getValue();
-        const APInt &AP2 = C2->getValue();
-        if (AP1.isNegative() == AP2.isNegative()) {
-          APInt AP1Abs = C1->getValue().abs();
-          APInt AP2Abs = C2->getValue().abs();
-          if (AP1Abs.uge(AP2Abs)) {
-            ConstantInt *C3 = Builder.getInt(AP1 - AP2);
-            Value *NewAdd = Builder.CreateNSWAdd(A, C3);
-            return new ICmpInst(Pred, NewAdd, C);
-          } else {
-            ConstantInt *C3 = Builder.getInt(AP2 - AP1);
-            Value *NewAdd = Builder.CreateNSWAdd(C, C3);
-            return new ICmpInst(Pred, A, NewAdd);
-          }
-        }
-      }
-
-  // Analyze the case when either Op0 or Op1 is a sub instruction.
-  // Op0 = A - B (or A and B are null); Op1 = C - D (or C and D are null).
-  A = nullptr;
-  B = nullptr;
-  C = nullptr;
-  D = nullptr;
-  if (BO0 && BO0->getOpcode() == Instruction::Sub) {
-    A = BO0->getOperand(0);
-    B = BO0->getOperand(1);
-  }
-  if (BO1 && BO1->getOpcode() == Instruction::Sub) {
-    C = BO1->getOperand(0);
-    D = BO1->getOperand(1);
-  }
-
-  // icmp (X-Y), X -> icmp 0, Y for equalities or if there is no overflow.
-  if (A == Op1 && NoOp0WrapProblem)
-    return new ICmpInst(Pred, Constant::getNullValue(Op1->getType()), B);
-  // icmp X, (X-Y) -> icmp Y, 0 for equalities or if there is no overflow.
-  if (C == Op0 && NoOp1WrapProblem)
-    return new ICmpInst(Pred, D, Constant::getNullValue(Op0->getType()));
-
-  // (A - B) >u A --> A <u B
-  if (A == Op1 && Pred == ICmpInst::ICMP_UGT)
-    return new ICmpInst(ICmpInst::ICMP_ULT, A, B);
-  // C <u (C - D) --> C <u D
-  if (C == Op0 && Pred == ICmpInst::ICMP_ULT)
-    return new ICmpInst(ICmpInst::ICMP_ULT, C, D);
-
-  // icmp (Y-X), (Z-X) -> icmp Y, Z for equalities or if there is no overflow.
-  if (B && D && B == D && NoOp0WrapProblem && NoOp1WrapProblem &&
-      // Try not to increase register pressure.
-      BO0->hasOneUse() && BO1->hasOneUse())
-    return new ICmpInst(Pred, A, C);
-  // icmp (X-Y), (X-Z) -> icmp Z, Y for equalities or if there is no overflow.
-  if (A && C && A == C && NoOp0WrapProblem && NoOp1WrapProblem &&
-      // Try not to increase register pressure.
-      BO0->hasOneUse() && BO1->hasOneUse())
-    return new ICmpInst(Pred, D, B);
-
-  // icmp (0-X) < cst --> x > -cst
-  if (NoOp0WrapProblem && ICmpInst::isSigned(Pred)) {
-    Value *X;
-    if (match(BO0, m_Neg(m_Value(X))))
-      if (Constant *RHSC = dyn_cast<Constant>(Op1))
-        if (RHSC->isNotMinSignedValue())
-          return new ICmpInst(I.getSwappedPredicate(), X,
-                              ConstantExpr::getNeg(RHSC));
-  }
-
-  BinaryOperator *SRem = nullptr;
-  // icmp (srem X, Y), Y
-  if (BO0 && BO0->getOpcode() == Instruction::SRem && Op1 == BO0->getOperand(1))
-    SRem = BO0;
-  // icmp Y, (srem X, Y)
-  else if (BO1 && BO1->getOpcode() == Instruction::SRem &&
-           Op0 == BO1->getOperand(1))
-    SRem = BO1;
-  if (SRem) {
-    // We don't check hasOneUse to avoid increasing register pressure because
-    // the value we use is the same value this instruction was already using.
-    switch (SRem == BO0 ? ICmpInst::getSwappedPredicate(Pred) : Pred) {
-    default:
-      break;
-    case ICmpInst::ICMP_EQ:
-      return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
-    case ICmpInst::ICMP_NE:
-      return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
-    case ICmpInst::ICMP_SGT:
-    case ICmpInst::ICMP_SGE:
-      return new ICmpInst(ICmpInst::ICMP_SGT, SRem->getOperand(1),
-                          Constant::getAllOnesValue(SRem->getType()));
-    case ICmpInst::ICMP_SLT:
-    case ICmpInst::ICMP_SLE:
-      return new ICmpInst(ICmpInst::ICMP_SLT, SRem->getOperand(1),
-                          Constant::getNullValue(SRem->getType()));
-    }
-  }
-
-  if (BO0 && BO1 && BO0->getOpcode() == BO1->getOpcode() && BO0->hasOneUse() &&
-      BO1->hasOneUse() && BO0->getOperand(1) == BO1->getOperand(1)) {
-    switch (BO0->getOpcode()) {
-    default:
-      break;
-    case Instruction::Add:
-    case Instruction::Sub:
-    case Instruction::Xor: {
-      if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
-        return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
-
-      const APInt *C;
-      if (match(BO0->getOperand(1), m_APInt(C))) {
-        // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
-        if (C->isSignMask()) {
-          ICmpInst::Predicate NewPred =
-              I.isSigned() ? I.getUnsignedPredicate() : I.getSignedPredicate();
-          return new ICmpInst(NewPred, BO0->getOperand(0), BO1->getOperand(0));
-        }
-
-        // icmp u/s (a ^ maxsignval), (b ^ maxsignval) --> icmp s/u' a, b
-        if (BO0->getOpcode() == Instruction::Xor && C->isMaxSignedValue()) {
-          ICmpInst::Predicate NewPred =
-              I.isSigned() ? I.getUnsignedPredicate() : I.getSignedPredicate();
-          NewPred = I.getSwappedPredicate(NewPred);
-          return new ICmpInst(NewPred, BO0->getOperand(0), BO1->getOperand(0));
-        }
-      }
-      break;
-    }
-    case Instruction::Mul: {
-      if (!I.isEquality())
-        break;
-
-      const APInt *C;
-      if (match(BO0->getOperand(1), m_APInt(C)) && !C->isNullValue() &&
-          !C->isOneValue()) {
-        // icmp eq/ne (X * C), (Y * C) --> icmp (X & Mask), (Y & Mask)
-        // Mask = -1 >> count-trailing-zeros(C).
-        if (unsigned TZs = C->countTrailingZeros()) {
-          Constant *Mask = ConstantInt::get(
-              BO0->getType(),
-              APInt::getLowBitsSet(C->getBitWidth(), C->getBitWidth() - TZs));
-          Value *And1 = Builder.CreateAnd(BO0->getOperand(0), Mask);
-          Value *And2 = Builder.CreateAnd(BO1->getOperand(0), Mask);
-          return new ICmpInst(Pred, And1, And2);
-        }
-        // If there are no trailing zeros in the multiplier, just eliminate
-        // the multiplies (no masking is needed):
-        // icmp eq/ne (X * C), (Y * C) --> icmp eq/ne X, Y
-        return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
-      }
-      break;
-    }
-    case Instruction::UDiv:
-    case Instruction::LShr:
-      if (I.isSigned() || !BO0->isExact() || !BO1->isExact())
-        break;
-      return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
-
-    case Instruction::SDiv:
-      if (!I.isEquality() || !BO0->isExact() || !BO1->isExact())
-        break;
-      return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
-
-    case Instruction::AShr:
-      if (!BO0->isExact() || !BO1->isExact())
-        break;
-      return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
-
-    case Instruction::Shl: {
-      bool NUW = BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap();
-      bool NSW = BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap();
-      if (!NUW && !NSW)
-        break;
-      if (!NSW && I.isSigned())
-        break;
-      return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
-    }
-    }
-  }
-
-  if (BO0) {
-    // Transform  A & (L - 1) `ult` L --> L != 0
-    auto LSubOne = m_Add(m_Specific(Op1), m_AllOnes());
-    auto BitwiseAnd = m_c_And(m_Value(), LSubOne);
-
-    if (match(BO0, BitwiseAnd) && Pred == ICmpInst::ICMP_ULT) {
-      auto *Zero = Constant::getNullValue(BO0->getType());
-      return new ICmpInst(ICmpInst::ICMP_NE, Op1, Zero);
-    }
-  }
-
-  if (Value *V = foldICmpWithLowBitMaskedVal(I, Builder))
-    return replaceInstUsesWith(I, V);
-
-  if (Value *V = foldICmpWithTruncSignExtendedVal(I, Builder))
-    return replaceInstUsesWith(I, V);
-
-  return nullptr;
-}
-
-/// Fold icmp Pred min|max(X, Y), X.
-static Instruction *foldICmpWithMinMax(ICmpInst &Cmp) {
-  ICmpInst::Predicate Pred = Cmp.getPredicate();
-  Value *Op0 = Cmp.getOperand(0);
-  Value *X = Cmp.getOperand(1);
-
-  // Canonicalize minimum or maximum operand to LHS of the icmp.
-  if (match(X, m_c_SMin(m_Specific(Op0), m_Value())) ||
-      match(X, m_c_SMax(m_Specific(Op0), m_Value())) ||
-      match(X, m_c_UMin(m_Specific(Op0), m_Value())) ||
-      match(X, m_c_UMax(m_Specific(Op0), m_Value()))) {
-    std::swap(Op0, X);
-    Pred = Cmp.getSwappedPredicate();
-  }
-
-  Value *Y;
-  if (match(Op0, m_c_SMin(m_Specific(X), m_Value(Y)))) {
-    // smin(X, Y)  == X --> X s<= Y
-    // smin(X, Y) s>= X --> X s<= Y
-    if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_SGE)
-      return new ICmpInst(ICmpInst::ICMP_SLE, X, Y);
-
-    // smin(X, Y) != X --> X s> Y
-    // smin(X, Y) s< X --> X s> Y
-    if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_SLT)
-      return new ICmpInst(ICmpInst::ICMP_SGT, X, Y);
-
-    // These cases should be handled in InstSimplify:
-    // smin(X, Y) s<= X --> true
-    // smin(X, Y) s> X --> false
-    return nullptr;
-  }
-
-  if (match(Op0, m_c_SMax(m_Specific(X), m_Value(Y)))) {
-    // smax(X, Y)  == X --> X s>= Y
-    // smax(X, Y) s<= X --> X s>= Y
-    if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_SLE)
-      return new ICmpInst(ICmpInst::ICMP_SGE, X, Y);
-
-    // smax(X, Y) != X --> X s< Y
-    // smax(X, Y) s> X --> X s< Y
-    if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_SGT)
-      return new ICmpInst(ICmpInst::ICMP_SLT, X, Y);
-
-    // These cases should be handled in InstSimplify:
-    // smax(X, Y) s>= X --> true
-    // smax(X, Y) s< X --> false
-    return nullptr;
-  }
-
-  if (match(Op0, m_c_UMin(m_Specific(X), m_Value(Y)))) {
-    // umin(X, Y)  == X --> X u<= Y
-    // umin(X, Y) u>= X --> X u<= Y
-    if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_UGE)
-      return new ICmpInst(ICmpInst::ICMP_ULE, X, Y);
-
-    // umin(X, Y) != X --> X u> Y
-    // umin(X, Y) u< X --> X u> Y
-    if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_ULT)
-      return new ICmpInst(ICmpInst::ICMP_UGT, X, Y);
-
-    // These cases should be handled in InstSimplify:
-    // umin(X, Y) u<= X --> true
-    // umin(X, Y) u> X --> false
-    return nullptr;
-  }
-
-  if (match(Op0, m_c_UMax(m_Specific(X), m_Value(Y)))) {
-    // umax(X, Y)  == X --> X u>= Y
-    // umax(X, Y) u<= X --> X u>= Y
-    if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_ULE)
-      return new ICmpInst(ICmpInst::ICMP_UGE, X, Y);
-
-    // umax(X, Y) != X --> X u< Y
-    // umax(X, Y) u> X --> X u< Y
-    if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_UGT)
-      return new ICmpInst(ICmpInst::ICMP_ULT, X, Y);
-
-    // These cases should be handled in InstSimplify:
-    // umax(X, Y) u>= X --> true
-    // umax(X, Y) u< X --> false
-    return nullptr;
-  }
-
-  return nullptr;
-}
-
-Instruction *InstCombiner::foldICmpEquality(ICmpInst &I) {
-  if (!I.isEquality())
-    return nullptr;
-
-  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-  const CmpInst::Predicate Pred = I.getPredicate();
-  Value *A, *B, *C, *D;
-  if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
-    if (A == Op1 || B == Op1) { // (A^B) == A  ->  B == 0
-      Value *OtherVal = A == Op1 ? B : A;
-      return new ICmpInst(Pred, OtherVal, Constant::getNullValue(A->getType()));
-    }
-
-    if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
-      // A^c1 == C^c2 --> A == C^(c1^c2)
-      ConstantInt *C1, *C2;
-      if (match(B, m_ConstantInt(C1)) && match(D, m_ConstantInt(C2)) &&
-          Op1->hasOneUse()) {
-        Constant *NC = Builder.getInt(C1->getValue() ^ C2->getValue());
-        Value *Xor = Builder.CreateXor(C, NC);
-        return new ICmpInst(Pred, A, Xor);
-      }
-
-      // A^B == A^D -> B == D
-      if (A == C)
-        return new ICmpInst(Pred, B, D);
-      if (A == D)
-        return new ICmpInst(Pred, B, C);
-      if (B == C)
-        return new ICmpInst(Pred, A, D);
-      if (B == D)
-        return new ICmpInst(Pred, A, C);
-    }
-  }
-
-  if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && (A == Op0 || B == Op0)) {
-    // A == (A^B)  ->  B == 0
-    Value *OtherVal = A == Op0 ? B : A;
-    return new ICmpInst(Pred, OtherVal, Constant::getNullValue(A->getType()));
-  }
-
-  // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
-  if (match(Op0, m_OneUse(m_And(m_Value(A), m_Value(B)))) &&
-      match(Op1, m_OneUse(m_And(m_Value(C), m_Value(D))))) {
-    Value *X = nullptr, *Y = nullptr, *Z = nullptr;
-
-    if (A == C) {
-      X = B;
-      Y = D;
-      Z = A;
-    } else if (A == D) {
-      X = B;
-      Y = C;
-      Z = A;
-    } else if (B == C) {
-      X = A;
-      Y = D;
-      Z = B;
-    } else if (B == D) {
-      X = A;
-      Y = C;
-      Z = B;
-    }
-
-    if (X) { // Build (X^Y) & Z
-      Op1 = Builder.CreateXor(X, Y);
-      Op1 = Builder.CreateAnd(Op1, Z);
-      I.setOperand(0, Op1);
-      I.setOperand(1, Constant::getNullValue(Op1->getType()));
-      return &I;
-    }
-  }
-
-  // Transform (zext A) == (B & (1<<X)-1) --> A == (trunc B)
-  // and       (B & (1<<X)-1) == (zext A) --> A == (trunc B)
-  ConstantInt *Cst1;
-  if ((Op0->hasOneUse() && match(Op0, m_ZExt(m_Value(A))) &&
-       match(Op1, m_And(m_Value(B), m_ConstantInt(Cst1)))) ||
-      (Op1->hasOneUse() && match(Op0, m_And(m_Value(B), m_ConstantInt(Cst1))) &&
-       match(Op1, m_ZExt(m_Value(A))))) {
-    APInt Pow2 = Cst1->getValue() + 1;
-    if (Pow2.isPowerOf2() && isa<IntegerType>(A->getType()) &&
-        Pow2.logBase2() == cast<IntegerType>(A->getType())->getBitWidth())
-      return new ICmpInst(Pred, A, Builder.CreateTrunc(B, A->getType()));
-  }
-
-  // (A >> C) == (B >> C) --> (A^B) u< (1 << C)
-  // For lshr and ashr pairs.
-  if ((match(Op0, m_OneUse(m_LShr(m_Value(A), m_ConstantInt(Cst1)))) &&
-       match(Op1, m_OneUse(m_LShr(m_Value(B), m_Specific(Cst1))))) ||
-      (match(Op0, m_OneUse(m_AShr(m_Value(A), m_ConstantInt(Cst1)))) &&
-       match(Op1, m_OneUse(m_AShr(m_Value(B), m_Specific(Cst1)))))) {
-    unsigned TypeBits = Cst1->getBitWidth();
-    unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits);
-    if (ShAmt < TypeBits && ShAmt != 0) {
-      ICmpInst::Predicate NewPred =
-          Pred == ICmpInst::ICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
-      Value *Xor = Builder.CreateXor(A, B, I.getName() + ".unshifted");
-      APInt CmpVal = APInt::getOneBitSet(TypeBits, ShAmt);
-      return new ICmpInst(NewPred, Xor, Builder.getInt(CmpVal));
-    }
-  }
-
-  // (A << C) == (B << C) --> ((A^B) & (~0U >> C)) == 0
-  if (match(Op0, m_OneUse(m_Shl(m_Value(A), m_ConstantInt(Cst1)))) &&
-      match(Op1, m_OneUse(m_Shl(m_Value(B), m_Specific(Cst1))))) {
-    unsigned TypeBits = Cst1->getBitWidth();
-    unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits);
-    if (ShAmt < TypeBits && ShAmt != 0) {
-      Value *Xor = Builder.CreateXor(A, B, I.getName() + ".unshifted");
-      APInt AndVal = APInt::getLowBitsSet(TypeBits, TypeBits - ShAmt);
-      Value *And = Builder.CreateAnd(Xor, Builder.getInt(AndVal),
-                                      I.getName() + ".mask");
-      return new ICmpInst(Pred, And, Constant::getNullValue(Cst1->getType()));
-    }
-  }
-
-  // Transform "icmp eq (trunc (lshr(X, cst1)), cst" to
-  // "icmp (and X, mask), cst"
-  uint64_t ShAmt = 0;
-  if (Op0->hasOneUse() &&
-      match(Op0, m_Trunc(m_OneUse(m_LShr(m_Value(A), m_ConstantInt(ShAmt))))) &&
-      match(Op1, m_ConstantInt(Cst1)) &&
-      // Only do this when A has multiple uses.  This is most important to do
-      // when it exposes other optimizations.
-      !A->hasOneUse()) {
-    unsigned ASize = cast<IntegerType>(A->getType())->getPrimitiveSizeInBits();
-
-    if (ShAmt < ASize) {
-      APInt MaskV =
-          APInt::getLowBitsSet(ASize, Op0->getType()->getPrimitiveSizeInBits());
-      MaskV <<= ShAmt;
-
-      APInt CmpV = Cst1->getValue().zext(ASize);
-      CmpV <<= ShAmt;
-
-      Value *Mask = Builder.CreateAnd(A, Builder.getInt(MaskV));
-      return new ICmpInst(Pred, Mask, Builder.getInt(CmpV));
-    }
-  }
-
-  // If both operands are byte-swapped or bit-reversed, just compare the
-  // original values.
-  // TODO: Move this to a function similar to foldICmpIntrinsicWithConstant()
-  // and handle more intrinsics.
-  if ((match(Op0, m_BSwap(m_Value(A))) && match(Op1, m_BSwap(m_Value(B)))) ||
-      (match(Op0, m_BitReverse(m_Value(A))) &&
-       match(Op1, m_BitReverse(m_Value(B)))))
-    return new ICmpInst(Pred, A, B);
-
-  return nullptr;
-}
-
-/// Handle icmp (cast x to y), (cast/cst). We only handle extending casts so
-/// far.
-Instruction *InstCombiner::foldICmpWithCastAndCast(ICmpInst &ICmp) {
-  const CastInst *LHSCI = cast<CastInst>(ICmp.getOperand(0));
-  Value *LHSCIOp        = LHSCI->getOperand(0);
-  Type *SrcTy     = LHSCIOp->getType();
-  Type *DestTy    = LHSCI->getType();
-  Value *RHSCIOp;
-
-  // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
-  // integer type is the same size as the pointer type.
-  const auto& CompatibleSizes = [&](Type* SrcTy, Type* DestTy) -> bool {
-    if (isa<VectorType>(SrcTy)) {
-      SrcTy = cast<VectorType>(SrcTy)->getElementType();
-      DestTy = cast<VectorType>(DestTy)->getElementType();
-    }
-    return DL.getPointerTypeSizeInBits(SrcTy) == DestTy->getIntegerBitWidth();
-  };
-  if (LHSCI->getOpcode() == Instruction::PtrToInt &&
-      CompatibleSizes(SrcTy, DestTy)) {
-    Value *RHSOp = nullptr;
-    if (auto *RHSC = dyn_cast<PtrToIntOperator>(ICmp.getOperand(1))) {
-      Value *RHSCIOp = RHSC->getOperand(0);
-      if (RHSCIOp->getType()->getPointerAddressSpace() ==
-          LHSCIOp->getType()->getPointerAddressSpace()) {
-        RHSOp = RHSC->getOperand(0);
-        // If the pointer types don't match, insert a bitcast.
-        if (LHSCIOp->getType() != RHSOp->getType())
-          RHSOp = Builder.CreateBitCast(RHSOp, LHSCIOp->getType());
-      }
-    } else if (auto *RHSC = dyn_cast<Constant>(ICmp.getOperand(1))) {
-      RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
-    }
-
-    if (RHSOp)
-      return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSOp);
-  }
-
-  // The code below only handles extension cast instructions, so far.
-  // Enforce this.
-  if (LHSCI->getOpcode() != Instruction::ZExt &&
-      LHSCI->getOpcode() != Instruction::SExt)
-    return nullptr;
-
-  bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
-  bool isSignedCmp = ICmp.isSigned();
-
-  if (auto *CI = dyn_cast<CastInst>(ICmp.getOperand(1))) {
-    // Not an extension from the same type?
-    RHSCIOp = CI->getOperand(0);
-    if (RHSCIOp->getType() != LHSCIOp->getType())
-      return nullptr;
-
-    // If the signedness of the two casts doesn't agree (i.e. one is a sext
-    // and the other is a zext), then we can't handle this.
-    if (CI->getOpcode() != LHSCI->getOpcode())
-      return nullptr;
-
-    // Deal with equality cases early.
-    if (ICmp.isEquality())
-      return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSCIOp);
-
-    // A signed comparison of sign extended values simplifies into a
-    // signed comparison.
-    if (isSignedCmp && isSignedExt)
-      return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSCIOp);
-
-    // The other three cases all fold into an unsigned comparison.
-    return new ICmpInst(ICmp.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
-  }
-
-  // If we aren't dealing with a constant on the RHS, exit early.
-  auto *C = dyn_cast<Constant>(ICmp.getOperand(1));
-  if (!C)
-    return nullptr;
-
-  // Compute the constant that would happen if we truncated to SrcTy then
-  // re-extended to DestTy.
-  Constant *Res1 = ConstantExpr::getTrunc(C, SrcTy);
-  Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy);
-
-  // If the re-extended constant didn't change...
-  if (Res2 == C) {
-    // Deal with equality cases early.
-    if (ICmp.isEquality())
-      return new ICmpInst(ICmp.getPredicate(), LHSCIOp, Res1);
-
-    // A signed comparison of sign extended values simplifies into a
-    // signed comparison.
-    if (isSignedExt && isSignedCmp)
-      return new ICmpInst(ICmp.getPredicate(), LHSCIOp, Res1);
-
-    // The other three cases all fold into an unsigned comparison.
-    return new ICmpInst(ICmp.getUnsignedPredicate(), LHSCIOp, Res1);
-  }
-
-  // The re-extended constant changed, partly changed (in the case of a vector),
-  // or could not be determined to be equal (in the case of a constant
-  // expression), so the constant cannot be represented in the shorter type.
-  // Consequently, we cannot emit a simple comparison.
-  // All the cases that fold to true or false will have already been handled
-  // by SimplifyICmpInst, so only deal with the tricky case.
-
-  if (isSignedCmp || !isSignedExt || !isa<ConstantInt>(C))
-    return nullptr;
-
-  // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
-  // should have been folded away previously and not enter in here.
-
-  // We're performing an unsigned comp with a sign extended value.
-  // This is true if the input is >= 0. [aka >s -1]
-  Constant *NegOne = Constant::getAllOnesValue(SrcTy);
-  Value *Result = Builder.CreateICmpSGT(LHSCIOp, NegOne, ICmp.getName());
-
-  // Finally, return the value computed.
-  if (ICmp.getPredicate() == ICmpInst::ICMP_ULT)
-    return replaceInstUsesWith(ICmp, Result);
-
-  assert(ICmp.getPredicate() == ICmpInst::ICMP_UGT && "ICmp should be folded!");
-  return BinaryOperator::CreateNot(Result);
-}
-
-bool InstCombiner::OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS,
-                                         Value *RHS, Instruction &OrigI,
-                                         Value *&Result, Constant *&Overflow) {
-  if (OrigI.isCommutative() && isa<Constant>(LHS) && !isa<Constant>(RHS))
-    std::swap(LHS, RHS);
-
-  auto SetResult = [&](Value *OpResult, Constant *OverflowVal, bool ReuseName) {
-    Result = OpResult;
-    Overflow = OverflowVal;
-    if (ReuseName)
-      Result->takeName(&OrigI);
-    return true;
-  };
-
-  // If the overflow check was an add followed by a compare, the insertion point
-  // may be pointing to the compare.  We want to insert the new instructions
-  // before the add in case there are uses of the add between the add and the
-  // compare.
-  Builder.SetInsertPoint(&OrigI);
-
-  switch (OCF) {
-  case OCF_INVALID:
-    llvm_unreachable("bad overflow check kind!");
-
-  case OCF_UNSIGNED_ADD: {
-    OverflowResult OR = computeOverflowForUnsignedAdd(LHS, RHS, &OrigI);
-    if (OR == OverflowResult::NeverOverflows)
-      return SetResult(Builder.CreateNUWAdd(LHS, RHS), Builder.getFalse(),
-                       true);
-
-    if (OR == OverflowResult::AlwaysOverflows)
-      return SetResult(Builder.CreateAdd(LHS, RHS), Builder.getTrue(), true);
-
-    // Fall through uadd into sadd
-    LLVM_FALLTHROUGH;
-  }
-  case OCF_SIGNED_ADD: {
-    // X + 0 -> {X, false}
-    if (match(RHS, m_Zero()))
-      return SetResult(LHS, Builder.getFalse(), false);
-
-    // We can strength reduce this signed add into a regular add if we can prove
-    // that it will never overflow.
-    if (OCF == OCF_SIGNED_ADD)
-      if (willNotOverflowSignedAdd(LHS, RHS, OrigI))
-        return SetResult(Builder.CreateNSWAdd(LHS, RHS), Builder.getFalse(),
-                         true);
-    break;
-  }
-
-  case OCF_UNSIGNED_SUB:
-  case OCF_SIGNED_SUB: {
-    // X - 0 -> {X, false}
-    if (match(RHS, m_Zero()))
-      return SetResult(LHS, Builder.getFalse(), false);
-
-    if (OCF == OCF_SIGNED_SUB) {
-      if (willNotOverflowSignedSub(LHS, RHS, OrigI))
-        return SetResult(Builder.CreateNSWSub(LHS, RHS), Builder.getFalse(),
-                         true);
-    } else {
-      if (willNotOverflowUnsignedSub(LHS, RHS, OrigI))
-        return SetResult(Builder.CreateNUWSub(LHS, RHS), Builder.getFalse(),
-                         true);
-    }
-    break;
-  }
-
-  case OCF_UNSIGNED_MUL: {
-    OverflowResult OR = computeOverflowForUnsignedMul(LHS, RHS, &OrigI);
-    if (OR == OverflowResult::NeverOverflows)
-      return SetResult(Builder.CreateNUWMul(LHS, RHS), Builder.getFalse(),
-                       true);
-    if (OR == OverflowResult::AlwaysOverflows)
-      return SetResult(Builder.CreateMul(LHS, RHS), Builder.getTrue(), true);
-    LLVM_FALLTHROUGH;
-  }
-  case OCF_SIGNED_MUL:
-    // X * undef -> undef
-    if (isa<UndefValue>(RHS))
-      return SetResult(RHS, UndefValue::get(Builder.getInt1Ty()), false);
-
-    // X * 0 -> {0, false}
-    if (match(RHS, m_Zero()))
-      return SetResult(RHS, Builder.getFalse(), false);
-
-    // X * 1 -> {X, false}
-    if (match(RHS, m_One()))
-      return SetResult(LHS, Builder.getFalse(), false);
-
-    if (OCF == OCF_SIGNED_MUL)
-      if (willNotOverflowSignedMul(LHS, RHS, OrigI))
-        return SetResult(Builder.CreateNSWMul(LHS, RHS), Builder.getFalse(),
-                         true);
-    break;
-  }
-
-  return false;
-}
-
-/// Recognize and process idiom involving test for multiplication
-/// overflow.
-///
-/// The caller has matched a pattern of the form:
-///   I = cmp u (mul(zext A, zext B), V
-/// The function checks if this is a test for overflow and if so replaces
-/// multiplication with call to 'mul.with.overflow' intrinsic.
-///
-/// \param I Compare instruction.
-/// \param MulVal Result of 'mult' instruction.  It is one of the arguments of
-///               the compare instruction.  Must be of integer type.
-/// \param OtherVal The other argument of compare instruction.
-/// \returns Instruction which must replace the compare instruction, NULL if no
-///          replacement required.
-static Instruction *processUMulZExtIdiom(ICmpInst &I, Value *MulVal,
-                                         Value *OtherVal, InstCombiner &IC) {
-  // Don't bother doing this transformation for pointers, don't do it for
-  // vectors.
-  if (!isa<IntegerType>(MulVal->getType()))
-    return nullptr;
-
-  assert(I.getOperand(0) == MulVal || I.getOperand(1) == MulVal);
-  assert(I.getOperand(0) == OtherVal || I.getOperand(1) == OtherVal);
-  auto *MulInstr = dyn_cast<Instruction>(MulVal);
-  if (!MulInstr)
-    return nullptr;
-  assert(MulInstr->getOpcode() == Instruction::Mul);
-
-  auto *LHS = cast<ZExtOperator>(MulInstr->getOperand(0)),
-       *RHS = cast<ZExtOperator>(MulInstr->getOperand(1));
-  assert(LHS->getOpcode() == Instruction::ZExt);
-  assert(RHS->getOpcode() == Instruction::ZExt);
-  Value *A = LHS->getOperand(0), *B = RHS->getOperand(0);
-
-  // Calculate type and width of the result produced by mul.with.overflow.
-  Type *TyA = A->getType(), *TyB = B->getType();
-  unsigned WidthA = TyA->getPrimitiveSizeInBits(),
-           WidthB = TyB->getPrimitiveSizeInBits();
-  unsigned MulWidth;
-  Type *MulType;
-  if (WidthB > WidthA) {
-    MulWidth = WidthB;
-    MulType = TyB;
-  } else {
-    MulWidth = WidthA;
-    MulType = TyA;
-  }
-
-  // In order to replace the original mul with a narrower mul.with.overflow,
-  // all uses must ignore upper bits of the product.  The number of used low
-  // bits must be not greater than the width of mul.with.overflow.
-  if (MulVal->hasNUsesOrMore(2))
-    for (User *U : MulVal->users()) {
-      if (U == &I)
-        continue;
-      if (TruncInst *TI = dyn_cast<TruncInst>(U)) {
-        // Check if truncation ignores bits above MulWidth.
-        unsigned TruncWidth = TI->getType()->getPrimitiveSizeInBits();
-        if (TruncWidth > MulWidth)
-          return nullptr;
-      } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
-        // Check if AND ignores bits above MulWidth.
-        if (BO->getOpcode() != Instruction::And)
-          return nullptr;
-        if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1))) {
-          const APInt &CVal = CI->getValue();
-          if (CVal.getBitWidth() - CVal.countLeadingZeros() > MulWidth)
-            return nullptr;
-        } else {
-          // In this case we could have the operand of the binary operation
-          // being defined in another block, and performing the replacement
-          // could break the dominance relation.
-          return nullptr;
-        }
-      } else {
-        // Other uses prohibit this transformation.
-        return nullptr;
-      }
-    }
-
-  // Recognize patterns
-  switch (I.getPredicate()) {
-  case ICmpInst::ICMP_EQ:
-  case ICmpInst::ICMP_NE:
-    // Recognize pattern:
-    //   mulval = mul(zext A, zext B)
-    //   cmp eq/neq mulval, zext trunc mulval
-    if (ZExtInst *Zext = dyn_cast<ZExtInst>(OtherVal))
-      if (Zext->hasOneUse()) {
-        Value *ZextArg = Zext->getOperand(0);
-        if (TruncInst *Trunc = dyn_cast<TruncInst>(ZextArg))
-          if (Trunc->getType()->getPrimitiveSizeInBits() == MulWidth)
-            break; //Recognized
-      }
-
-    // Recognize pattern:
-    //   mulval = mul(zext A, zext B)
-    //   cmp eq/neq mulval, and(mulval, mask), mask selects low MulWidth bits.
-    ConstantInt *CI;
-    Value *ValToMask;
-    if (match(OtherVal, m_And(m_Value(ValToMask), m_ConstantInt(CI)))) {
-      if (ValToMask != MulVal)
-        return nullptr;
-      const APInt &CVal = CI->getValue() + 1;
-      if (CVal.isPowerOf2()) {
-        unsigned MaskWidth = CVal.logBase2();
-        if (MaskWidth == MulWidth)
-          break; // Recognized
-      }
-    }
-    return nullptr;
-
-  case ICmpInst::ICMP_UGT:
-    // Recognize pattern:
-    //   mulval = mul(zext A, zext B)
-    //   cmp ugt mulval, max
-    if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
-      APInt MaxVal = APInt::getMaxValue(MulWidth);
-      MaxVal = MaxVal.zext(CI->getBitWidth());
-      if (MaxVal.eq(CI->getValue()))
-        break; // Recognized
-    }
-    return nullptr;
-
-  case ICmpInst::ICMP_UGE:
-    // Recognize pattern:
-    //   mulval = mul(zext A, zext B)
-    //   cmp uge mulval, max+1
-    if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
-      APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth);
-      if (MaxVal.eq(CI->getValue()))
-        break; // Recognized
-    }
-    return nullptr;
-
-  case ICmpInst::ICMP_ULE:
-    // Recognize pattern:
-    //   mulval = mul(zext A, zext B)
-    //   cmp ule mulval, max
-    if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
-      APInt MaxVal = APInt::getMaxValue(MulWidth);
-      MaxVal = MaxVal.zext(CI->getBitWidth());
-      if (MaxVal.eq(CI->getValue()))
-        break; // Recognized
-    }
-    return nullptr;
-
-  case ICmpInst::ICMP_ULT:
-    // Recognize pattern:
-    //   mulval = mul(zext A, zext B)
-    //   cmp ule mulval, max + 1
-    if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
-      APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth);
-      if (MaxVal.eq(CI->getValue()))
-        break; // Recognized
-    }
-    return nullptr;
-
-  default:
-    return nullptr;
-  }
-
-  InstCombiner::BuilderTy &Builder = IC.Builder;
-  Builder.SetInsertPoint(MulInstr);
-
-  // Replace: mul(zext A, zext B) --> mul.with.overflow(A, B)
-  Value *MulA = A, *MulB = B;
-  if (WidthA < MulWidth)
-    MulA = Builder.CreateZExt(A, MulType);
-  if (WidthB < MulWidth)
-    MulB = Builder.CreateZExt(B, MulType);
-  Value *F = Intrinsic::getDeclaration(I.getModule(),
-                                       Intrinsic::umul_with_overflow, MulType);
-  CallInst *Call = Builder.CreateCall(F, {MulA, MulB}, "umul");
-  IC.Worklist.Add(MulInstr);
-
-  // If there are uses of mul result other than the comparison, we know that
-  // they are truncation or binary AND. Change them to use result of
-  // mul.with.overflow and adjust properly mask/size.
-  if (MulVal->hasNUsesOrMore(2)) {
-    Value *Mul = Builder.CreateExtractValue(Call, 0, "umul.value");
-    for (auto UI = MulVal->user_begin(), UE = MulVal->user_end(); UI != UE;) {
-      User *U = *UI++;
-      if (U == &I || U == OtherVal)
-        continue;
-      if (TruncInst *TI = dyn_cast<TruncInst>(U)) {
-        if (TI->getType()->getPrimitiveSizeInBits() == MulWidth)
-          IC.replaceInstUsesWith(*TI, Mul);
-        else
-          TI->setOperand(0, Mul);
-      } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
-        assert(BO->getOpcode() == Instruction::And);
-        // Replace (mul & mask) --> zext (mul.with.overflow & short_mask)
-        ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1));
-        APInt ShortMask = CI->getValue().trunc(MulWidth);
-        Value *ShortAnd = Builder.CreateAnd(Mul, ShortMask);
-        Instruction *Zext =
-            cast<Instruction>(Builder.CreateZExt(ShortAnd, BO->getType()));
-        IC.Worklist.Add(Zext);
-        IC.replaceInstUsesWith(*BO, Zext);
-      } else {
-        llvm_unreachable("Unexpected Binary operation");
-      }
-      IC.Worklist.Add(cast<Instruction>(U));
-    }
-  }
-  if (isa<Instruction>(OtherVal))
-    IC.Worklist.Add(cast<Instruction>(OtherVal));
-
-  // The original icmp gets replaced with the overflow value, maybe inverted
-  // depending on predicate.
-  bool Inverse = false;
-  switch (I.getPredicate()) {
-  case ICmpInst::ICMP_NE:
-    break;
-  case ICmpInst::ICMP_EQ:
-    Inverse = true;
-    break;
-  case ICmpInst::ICMP_UGT:
-  case ICmpInst::ICMP_UGE:
-    if (I.getOperand(0) == MulVal)
-      break;
-    Inverse = true;
-    break;
-  case ICmpInst::ICMP_ULT:
-  case ICmpInst::ICMP_ULE:
-    if (I.getOperand(1) == MulVal)
-      break;
-    Inverse = true;
-    break;
-  default:
-    llvm_unreachable("Unexpected predicate");
-  }
-  if (Inverse) {
-    Value *Res = Builder.CreateExtractValue(Call, 1);
-    return BinaryOperator::CreateNot(Res);
-  }
-
-  return ExtractValueInst::Create(Call, 1);
-}
-
-/// When performing a comparison against a constant, it is possible that not all
-/// the bits in the LHS are demanded. This helper method computes the mask that
-/// IS demanded.
-static APInt getDemandedBitsLHSMask(ICmpInst &I, unsigned BitWidth) {
-  const APInt *RHS;
-  if (!match(I.getOperand(1), m_APInt(RHS)))
-    return APInt::getAllOnesValue(BitWidth);
-
-  // If this is a normal comparison, it demands all bits. If it is a sign bit
-  // comparison, it only demands the sign bit.
-  bool UnusedBit;
-  if (isSignBitCheck(I.getPredicate(), *RHS, UnusedBit))
-    return APInt::getSignMask(BitWidth);
-
-  switch (I.getPredicate()) {
-  // For a UGT comparison, we don't care about any bits that
-  // correspond to the trailing ones of the comparand.  The value of these
-  // bits doesn't impact the outcome of the comparison, because any value
-  // greater than the RHS must differ in a bit higher than these due to carry.
-  case ICmpInst::ICMP_UGT:
-    return APInt::getBitsSetFrom(BitWidth, RHS->countTrailingOnes());
-
-  // Similarly, for a ULT comparison, we don't care about the trailing zeros.
-  // Any value less than the RHS must differ in a higher bit because of carries.
-  case ICmpInst::ICMP_ULT:
-    return APInt::getBitsSetFrom(BitWidth, RHS->countTrailingZeros());
-
-  default:
-    return APInt::getAllOnesValue(BitWidth);
-  }
-}
-
-/// Check if the order of \p Op0 and \p Op1 as operands in an ICmpInst
-/// should be swapped.
-/// The decision is based on how many times these two operands are reused
-/// as subtract operands and their positions in those instructions.
-/// The rationale is that several architectures use the same instruction for
-/// both subtract and cmp. Thus, it is better if the order of those operands
-/// match.
-/// \return true if Op0 and Op1 should be swapped.
-static bool swapMayExposeCSEOpportunities(const Value *Op0, const Value *Op1) {
-  // Filter out pointer values as those cannot appear directly in subtract.
-  // FIXME: we may want to go through inttoptrs or bitcasts.
-  if (Op0->getType()->isPointerTy())
-    return false;
-  // If a subtract already has the same operands as a compare, swapping would be
-  // bad. If a subtract has the same operands as a compare but in reverse order,
-  // then swapping is good.
-  int GoodToSwap = 0;
-  for (const User *U : Op0->users()) {
-    if (match(U, m_Sub(m_Specific(Op1), m_Specific(Op0))))
-      GoodToSwap++;
-    else if (match(U, m_Sub(m_Specific(Op0), m_Specific(Op1))))
-      GoodToSwap--;
-  }
-  return GoodToSwap > 0;
-}
-
-/// Check that one use is in the same block as the definition and all
-/// other uses are in blocks dominated by a given block.
-///
-/// \param DI Definition
-/// \param UI Use
-/// \param DB Block that must dominate all uses of \p DI outside
-///           the parent block
-/// \return true when \p UI is the only use of \p DI in the parent block
-/// and all other uses of \p DI are in blocks dominated by \p DB.
-///
-bool InstCombiner::dominatesAllUses(const Instruction *DI,
-                                    const Instruction *UI,
-                                    const BasicBlock *DB) const {
-  assert(DI && UI && "Instruction not defined\n");
-  // Ignore incomplete definitions.
-  if (!DI->getParent())
-    return false;
-  // DI and UI must be in the same block.
-  if (DI->getParent() != UI->getParent())
-    return false;
-  // Protect from self-referencing blocks.
-  if (DI->getParent() == DB)
-    return false;
-  for (const User *U : DI->users()) {
-    auto *Usr = cast<Instruction>(U);
-    if (Usr != UI && !DT.dominates(DB, Usr->getParent()))
-      return false;
-  }
-  return true;
-}
-
-/// Return true when the instruction sequence within a block is select-cmp-br.
-static bool isChainSelectCmpBranch(const SelectInst *SI) {
-  const BasicBlock *BB = SI->getParent();
-  if (!BB)
-    return false;
-  auto *BI = dyn_cast_or_null<BranchInst>(BB->getTerminator());
-  if (!BI || BI->getNumSuccessors() != 2)
-    return false;
-  auto *IC = dyn_cast<ICmpInst>(BI->getCondition());
-  if (!IC || (IC->getOperand(0) != SI && IC->getOperand(1) != SI))
-    return false;
-  return true;
-}
-
-/// True when a select result is replaced by one of its operands
-/// in select-icmp sequence. This will eventually result in the elimination
-/// of the select.
-///
-/// \param SI    Select instruction
-/// \param Icmp  Compare instruction
-/// \param SIOpd Operand that replaces the select
-///
-/// Notes:
-/// - The replacement is global and requires dominator information
-/// - The caller is responsible for the actual replacement
-///
-/// Example:
-///
-/// entry:
-///  %4 = select i1 %3, %C* %0, %C* null
-///  %5 = icmp eq %C* %4, null
-///  br i1 %5, label %9, label %7
-///  ...
-///  ; <label>:7                                       ; preds = %entry
-///  %8 = getelementptr inbounds %C* %4, i64 0, i32 0
-///  ...
-///
-/// can be transformed to
-///
-///  %5 = icmp eq %C* %0, null
-///  %6 = select i1 %3, i1 %5, i1 true
-///  br i1 %6, label %9, label %7
-///  ...
-///  ; <label>:7                                       ; preds = %entry
-///  %8 = getelementptr inbounds %C* %0, i64 0, i32 0  // replace by %0!
-///
-/// Similar when the first operand of the select is a constant or/and
-/// the compare is for not equal rather than equal.
-///
-/// NOTE: The function is only called when the select and compare constants
-/// are equal, the optimization can work only for EQ predicates. This is not a
-/// major restriction since a NE compare should be 'normalized' to an equal
-/// compare, which usually happens in the combiner and test case
-/// select-cmp-br.ll checks for it.
-bool InstCombiner::replacedSelectWithOperand(SelectInst *SI,
-                                             const ICmpInst *Icmp,
-                                             const unsigned SIOpd) {
-  assert((SIOpd == 1 || SIOpd == 2) && "Invalid select operand!");
-  if (isChainSelectCmpBranch(SI) && Icmp->getPredicate() == ICmpInst::ICMP_EQ) {
-    BasicBlock *Succ = SI->getParent()->getTerminator()->getSuccessor(1);
-    // The check for the single predecessor is not the best that can be
-    // done. But it protects efficiently against cases like when SI's
-    // home block has two successors, Succ and Succ1, and Succ1 predecessor
-    // of Succ. Then SI can't be replaced by SIOpd because the use that gets
-    // replaced can be reached on either path. So the uniqueness check
-    // guarantees that the path all uses of SI (outside SI's parent) are on
-    // is disjoint from all other paths out of SI. But that information
-    // is more expensive to compute, and the trade-off here is in favor
-    // of compile-time. It should also be noticed that we check for a single
-    // predecessor and not only uniqueness. This to handle the situation when
-    // Succ and Succ1 points to the same basic block.
-    if (Succ->getSinglePredecessor() && dominatesAllUses(SI, Icmp, Succ)) {
-      NumSel++;
-      SI->replaceUsesOutsideBlock(SI->getOperand(SIOpd), SI->getParent());
-      return true;
-    }
-  }
-  return false;
-}
-
-/// Try to fold the comparison based on range information we can get by checking
-/// whether bits are known to be zero or one in the inputs.
-Instruction *InstCombiner::foldICmpUsingKnownBits(ICmpInst &I) {
-  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-  Type *Ty = Op0->getType();
-  ICmpInst::Predicate Pred = I.getPredicate();
-
-  // Get scalar or pointer size.
-  unsigned BitWidth = Ty->isIntOrIntVectorTy()
-                          ? Ty->getScalarSizeInBits()
-                          : DL.getIndexTypeSizeInBits(Ty->getScalarType());
-
-  if (!BitWidth)
-    return nullptr;
-
-  KnownBits Op0Known(BitWidth);
-  KnownBits Op1Known(BitWidth);
-
-  if (SimplifyDemandedBits(&I, 0,
-                           getDemandedBitsLHSMask(I, BitWidth),
-                           Op0Known, 0))
-    return &I;
-
-  if (SimplifyDemandedBits(&I, 1, APInt::getAllOnesValue(BitWidth),
-                           Op1Known, 0))
-    return &I;
-
-  // Given the known and unknown bits, compute a range that the LHS could be
-  // in.  Compute the Min, Max and RHS values based on the known bits. For the
-  // EQ and NE we use unsigned values.
-  APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
-  APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
-  if (I.isSigned()) {
-    computeSignedMinMaxValuesFromKnownBits(Op0Known, Op0Min, Op0Max);
-    computeSignedMinMaxValuesFromKnownBits(Op1Known, Op1Min, Op1Max);
-  } else {
-    computeUnsignedMinMaxValuesFromKnownBits(Op0Known, Op0Min, Op0Max);
-    computeUnsignedMinMaxValuesFromKnownBits(Op1Known, Op1Min, Op1Max);
-  }
-
-  // If Min and Max are known to be the same, then SimplifyDemandedBits figured
-  // out that the LHS or RHS is a constant. Constant fold this now, so that
-  // code below can assume that Min != Max.
-  if (!isa<Constant>(Op0) && Op0Min == Op0Max)
-    return new ICmpInst(Pred, ConstantExpr::getIntegerValue(Ty, Op0Min), Op1);
-  if (!isa<Constant>(Op1) && Op1Min == Op1Max)
-    return new ICmpInst(Pred, Op0, ConstantExpr::getIntegerValue(Ty, Op1Min));
-
-  // Based on the range information we know about the LHS, see if we can
-  // simplify this comparison.  For example, (x&4) < 8 is always true.
-  switch (Pred) {
-  default:
-    llvm_unreachable("Unknown icmp opcode!");
-  case ICmpInst::ICMP_EQ:
-  case ICmpInst::ICMP_NE: {
-    if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max)) {
-      return Pred == CmpInst::ICMP_EQ
-                 ? replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()))
-                 : replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
-    }
-
-    // If all bits are known zero except for one, then we know at most one bit
-    // is set. If the comparison is against zero, then this is a check to see if
-    // *that* bit is set.
-    APInt Op0KnownZeroInverted = ~Op0Known.Zero;
-    if (Op1Known.isZero()) {
-      // If the LHS is an AND with the same constant, look through it.
-      Value *LHS = nullptr;
-      const APInt *LHSC;
-      if (!match(Op0, m_And(m_Value(LHS), m_APInt(LHSC))) ||
-          *LHSC != Op0KnownZeroInverted)
-        LHS = Op0;
-
-      Value *X;
-      if (match(LHS, m_Shl(m_One(), m_Value(X)))) {
-        APInt ValToCheck = Op0KnownZeroInverted;
-        Type *XTy = X->getType();
-        if (ValToCheck.isPowerOf2()) {
-          // ((1 << X) & 8) == 0 -> X != 3
-          // ((1 << X) & 8) != 0 -> X == 3
-          auto *CmpC = ConstantInt::get(XTy, ValToCheck.countTrailingZeros());
-          auto NewPred = ICmpInst::getInversePredicate(Pred);
-          return new ICmpInst(NewPred, X, CmpC);
-        } else if ((++ValToCheck).isPowerOf2()) {
-          // ((1 << X) & 7) == 0 -> X >= 3
-          // ((1 << X) & 7) != 0 -> X  < 3
-          auto *CmpC = ConstantInt::get(XTy, ValToCheck.countTrailingZeros());
-          auto NewPred =
-              Pred == CmpInst::ICMP_EQ ? CmpInst::ICMP_UGE : CmpInst::ICMP_ULT;
-          return new ICmpInst(NewPred, X, CmpC);
-        }
-      }
-
-      // Check if the LHS is 8 >>u x and the result is a power of 2 like 1.
-      const APInt *CI;
-      if (Op0KnownZeroInverted.isOneValue() &&
-          match(LHS, m_LShr(m_Power2(CI), m_Value(X)))) {
-        // ((8 >>u X) & 1) == 0 -> X != 3
-        // ((8 >>u X) & 1) != 0 -> X == 3
-        unsigned CmpVal = CI->countTrailingZeros();
-        auto NewPred = ICmpInst::getInversePredicate(Pred);
-        return new ICmpInst(NewPred, X, ConstantInt::get(X->getType(), CmpVal));
-      }
-    }
-    break;
-  }
-  case ICmpInst::ICMP_ULT: {
-    if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
-      return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
-    if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B)
-      return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
-    if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B)
-      return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
-
-    const APInt *CmpC;
-    if (match(Op1, m_APInt(CmpC))) {
-      // A <u C -> A == C-1 if min(A)+1 == C
-      if (*CmpC == Op0Min + 1)
-        return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
-                            ConstantInt::get(Op1->getType(), *CmpC - 1));
-      // X <u C --> X == 0, if the number of zero bits in the bottom of X
-      // exceeds the log2 of C.
-      if (Op0Known.countMinTrailingZeros() >= CmpC->ceilLogBase2())
-        return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
-                            Constant::getNullValue(Op1->getType()));
-    }
-    break;
-  }
-  case ICmpInst::ICMP_UGT: {
-    if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B)
-      return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
-    if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B)
-      return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
-    if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B)
-      return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
-
-    const APInt *CmpC;
-    if (match(Op1, m_APInt(CmpC))) {
-      // A >u C -> A == C+1 if max(a)-1 == C
-      if (*CmpC == Op0Max - 1)
-        return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
-                            ConstantInt::get(Op1->getType(), *CmpC + 1));
-      // X >u C --> X != 0, if the number of zero bits in the bottom of X
-      // exceeds the log2 of C.
-      if (Op0Known.countMinTrailingZeros() >= CmpC->getActiveBits())
-        return new ICmpInst(ICmpInst::ICMP_NE, Op0,
-                            Constant::getNullValue(Op1->getType()));
-    }
-    break;
-  }
-  case ICmpInst::ICMP_SLT: {
-    if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C)
-      return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
-    if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C)
-      return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
-    if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
-      return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
-    const APInt *CmpC;
-    if (match(Op1, m_APInt(CmpC))) {
-      if (*CmpC == Op0Min + 1) // A <s C -> A == C-1 if min(A)+1 == C
-        return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
-                            ConstantInt::get(Op1->getType(), *CmpC - 1));
-    }
-    break;
-  }
-  case ICmpInst::ICMP_SGT: {
-    if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B)
-      return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
-    if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
-      return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
-    if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
-      return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
-    const APInt *CmpC;
-    if (match(Op1, m_APInt(CmpC))) {
-      if (*CmpC == Op0Max - 1) // A >s C -> A == C+1 if max(A)-1 == C
-        return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
-                            ConstantInt::get(Op1->getType(), *CmpC + 1));
-    }
-    break;
-  }
-  case ICmpInst::ICMP_SGE:
-    assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!");
-    if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B)
-      return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
-    if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B)
-      return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
-    if (Op1Min == Op0Max) // A >=s B -> A == B if max(A) == min(B)
-      return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
-    break;
-  case ICmpInst::ICMP_SLE:
-    assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!");
-    if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B)
-      return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
-    if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B)
-      return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
-    if (Op1Max == Op0Min) // A <=s B -> A == B if min(A) == max(B)
-      return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
-    break;
-  case ICmpInst::ICMP_UGE:
-    assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!");
-    if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B)
-      return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
-    if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B)
-      return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
-    if (Op1Min == Op0Max) // A >=u B -> A == B if max(A) == min(B)
-      return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
-    break;
-  case ICmpInst::ICMP_ULE:
-    assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!");
-    if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B)
-      return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
-    if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B)
-      return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
-    if (Op1Max == Op0Min) // A <=u B -> A == B if min(A) == max(B)
-      return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
-    break;
-  }
-
-  // Turn a signed comparison into an unsigned one if both operands are known to
-  // have the same sign.
-  if (I.isSigned() &&
-      ((Op0Known.Zero.isNegative() && Op1Known.Zero.isNegative()) ||
-       (Op0Known.One.isNegative() && Op1Known.One.isNegative())))
-    return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
-
-  return nullptr;
-}
-
-/// If we have an icmp le or icmp ge instruction with a constant operand, turn
-/// it into the appropriate icmp lt or icmp gt instruction. This transform
-/// allows them to be folded in visitICmpInst.
-static ICmpInst *canonicalizeCmpWithConstant(ICmpInst &I) {
-  ICmpInst::Predicate Pred = I.getPredicate();
-  if (Pred != ICmpInst::ICMP_SLE && Pred != ICmpInst::ICMP_SGE &&
-      Pred != ICmpInst::ICMP_ULE && Pred != ICmpInst::ICMP_UGE)
-    return nullptr;
-
-  Value *Op0 = I.getOperand(0);
-  Value *Op1 = I.getOperand(1);
-  auto *Op1C = dyn_cast<Constant>(Op1);
-  if (!Op1C)
-    return nullptr;
-
-  // Check if the constant operand can be safely incremented/decremented without
-  // overflowing/underflowing. For scalars, SimplifyICmpInst has already handled
-  // the edge cases for us, so we just assert on them. For vectors, we must
-  // handle the edge cases.
-  Type *Op1Type = Op1->getType();
-  bool IsSigned = I.isSigned();
-  bool IsLE = (Pred == ICmpInst::ICMP_SLE || Pred == ICmpInst::ICMP_ULE);
-  auto *CI = dyn_cast<ConstantInt>(Op1C);
-  if (CI) {
-    // A <= MAX -> TRUE ; A >= MIN -> TRUE
-    assert(IsLE ? !CI->isMaxValue(IsSigned) : !CI->isMinValue(IsSigned));
-  } else if (Op1Type->isVectorTy()) {
-    // TODO? If the edge cases for vectors were guaranteed to be handled as they
-    // are for scalar, we could remove the min/max checks. However, to do that,
-    // we would have to use insertelement/shufflevector to replace edge values.
-    unsigned NumElts = Op1Type->getVectorNumElements();
-    for (unsigned i = 0; i != NumElts; ++i) {
-      Constant *Elt = Op1C->getAggregateElement(i);
-      if (!Elt)
-        return nullptr;
-
-      if (isa<UndefValue>(Elt))
-        continue;
-
-      // Bail out if we can't determine if this constant is min/max or if we
-      // know that this constant is min/max.
-      auto *CI = dyn_cast<ConstantInt>(Elt);
-      if (!CI || (IsLE ? CI->isMaxValue(IsSigned) : CI->isMinValue(IsSigned)))
-        return nullptr;
-    }
-  } else {
-    // ConstantExpr?
-    return nullptr;
-  }
-
-  // Increment or decrement the constant and set the new comparison predicate:
-  // ULE -> ULT ; UGE -> UGT ; SLE -> SLT ; SGE -> SGT
-  Constant *OneOrNegOne = ConstantInt::get(Op1Type, IsLE ? 1 : -1, true);
-  CmpInst::Predicate NewPred = IsLE ? ICmpInst::ICMP_ULT: ICmpInst::ICMP_UGT;
-  NewPred = IsSigned ? ICmpInst::getSignedPredicate(NewPred) : NewPred;
-  return new ICmpInst(NewPred, Op0, ConstantExpr::getAdd(Op1C, OneOrNegOne));
-}
-
-/// Integer compare with boolean values can always be turned into bitwise ops.
-static Instruction *canonicalizeICmpBool(ICmpInst &I,
-                                         InstCombiner::BuilderTy &Builder) {
-  Value *A = I.getOperand(0), *B = I.getOperand(1);
-  assert(A->getType()->isIntOrIntVectorTy(1) && "Bools only");
-
-  // A boolean compared to true/false can be simplified to Op0/true/false in
-  // 14 out of the 20 (10 predicates * 2 constants) possible combinations.
-  // Cases not handled by InstSimplify are always 'not' of Op0.
-  if (match(B, m_Zero())) {
-    switch (I.getPredicate()) {
-      case CmpInst::ICMP_EQ:  // A ==   0 -> !A
-      case CmpInst::ICMP_ULE: // A <=u  0 -> !A
-      case CmpInst::ICMP_SGE: // A >=s  0 -> !A
-        return BinaryOperator::CreateNot(A);
-      default:
-        llvm_unreachable("ICmp i1 X, C not simplified as expected.");
-    }
-  } else if (match(B, m_One())) {
-    switch (I.getPredicate()) {
-      case CmpInst::ICMP_NE:  // A !=  1 -> !A
-      case CmpInst::ICMP_ULT: // A <u  1 -> !A
-      case CmpInst::ICMP_SGT: // A >s -1 -> !A
-        return BinaryOperator::CreateNot(A);
-      default:
-        llvm_unreachable("ICmp i1 X, C not simplified as expected.");
-    }
-  }
-
-  switch (I.getPredicate()) {
-  default:
-    llvm_unreachable("Invalid icmp instruction!");
-  case ICmpInst::ICMP_EQ:
-    // icmp eq i1 A, B -> ~(A ^ B)
-    return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
-
-  case ICmpInst::ICMP_NE:
-    // icmp ne i1 A, B -> A ^ B
-    return BinaryOperator::CreateXor(A, B);
-
-  case ICmpInst::ICMP_UGT:
-    // icmp ugt -> icmp ult
-    std::swap(A, B);
-    LLVM_FALLTHROUGH;
-  case ICmpInst::ICMP_ULT:
-    // icmp ult i1 A, B -> ~A & B
-    return BinaryOperator::CreateAnd(Builder.CreateNot(A), B);
-
-  case ICmpInst::ICMP_SGT:
-    // icmp sgt -> icmp slt
-    std::swap(A, B);
-    LLVM_FALLTHROUGH;
-  case ICmpInst::ICMP_SLT:
-    // icmp slt i1 A, B -> A & ~B
-    return BinaryOperator::CreateAnd(Builder.CreateNot(B), A);
-
-  case ICmpInst::ICMP_UGE:
-    // icmp uge -> icmp ule
-    std::swap(A, B);
-    LLVM_FALLTHROUGH;
-  case ICmpInst::ICMP_ULE:
-    // icmp ule i1 A, B -> ~A | B
-    return BinaryOperator::CreateOr(Builder.CreateNot(A), B);
-
-  case ICmpInst::ICMP_SGE:
-    // icmp sge -> icmp sle
-    std::swap(A, B);
-    LLVM_FALLTHROUGH;
-  case ICmpInst::ICMP_SLE:
-    // icmp sle i1 A, B -> A | ~B
-    return BinaryOperator::CreateOr(Builder.CreateNot(B), A);
-  }
-}
-
-// Transform pattern like:
-//   (1 << Y) u<= X  or  ~(-1 << Y) u<  X  or  ((1 << Y)+(-1)) u<  X
-//   (1 << Y) u>  X  or  ~(-1 << Y) u>= X  or  ((1 << Y)+(-1)) u>= X
-// Into:
-//   (X l>> Y) != 0
-//   (X l>> Y) == 0
-static Instruction *foldICmpWithHighBitMask(ICmpInst &Cmp,
-                                            InstCombiner::BuilderTy &Builder) {
-  ICmpInst::Predicate Pred, NewPred;
-  Value *X, *Y;
-  if (match(&Cmp,
-            m_c_ICmp(Pred, m_OneUse(m_Shl(m_One(), m_Value(Y))), m_Value(X)))) {
-    // We want X to be the icmp's second operand, so swap predicate if it isn't.
-    if (Cmp.getOperand(0) == X)
-      Pred = Cmp.getSwappedPredicate();
-
-    switch (Pred) {
-    case ICmpInst::ICMP_ULE:
-      NewPred = ICmpInst::ICMP_NE;
-      break;
-    case ICmpInst::ICMP_UGT:
-      NewPred = ICmpInst::ICMP_EQ;
-      break;
-    default:
-      return nullptr;
-    }
-  } else if (match(&Cmp, m_c_ICmp(Pred,
-                                  m_OneUse(m_CombineOr(
-                                      m_Not(m_Shl(m_AllOnes(), m_Value(Y))),
-                                      m_Add(m_Shl(m_One(), m_Value(Y)),
-                                            m_AllOnes()))),
-                                  m_Value(X)))) {
-    // The variant with 'add' is not canonical, (the variant with 'not' is)
-    // we only get it because it has extra uses, and can't be canonicalized,
-
-    // We want X to be the icmp's second operand, so swap predicate if it isn't.
-    if (Cmp.getOperand(0) == X)
-      Pred = Cmp.getSwappedPredicate();
-
-    switch (Pred) {
-    case ICmpInst::ICMP_ULT:
-      NewPred = ICmpInst::ICMP_NE;
-      break;
-    case ICmpInst::ICMP_UGE:
-      NewPred = ICmpInst::ICMP_EQ;
-      break;
-    default:
-      return nullptr;
-    }
-  } else
-    return nullptr;
-
-  Value *NewX = Builder.CreateLShr(X, Y, X->getName() + ".highbits");
-  Constant *Zero = Constant::getNullValue(NewX->getType());
-  return CmpInst::Create(Instruction::ICmp, NewPred, NewX, Zero);
-}
-
-static Instruction *foldVectorCmp(CmpInst &Cmp,
-                                  InstCombiner::BuilderTy &Builder) {
-  // If both arguments of the cmp are shuffles that use the same mask and
-  // shuffle within a single vector, move the shuffle after the cmp.
-  Value *LHS = Cmp.getOperand(0), *RHS = Cmp.getOperand(1);
-  Value *V1, *V2;
-  Constant *M;
-  if (match(LHS, m_ShuffleVector(m_Value(V1), m_Undef(), m_Constant(M))) &&
-      match(RHS, m_ShuffleVector(m_Value(V2), m_Undef(), m_Specific(M))) &&
-      V1->getType() == V2->getType() &&
-      (LHS->hasOneUse() || RHS->hasOneUse())) {
-    // cmp (shuffle V1, M), (shuffle V2, M) --> shuffle (cmp V1, V2), M
-    CmpInst::Predicate P = Cmp.getPredicate();
-    Value *NewCmp = isa<ICmpInst>(Cmp) ? Builder.CreateICmp(P, V1, V2)
-                                       : Builder.CreateFCmp(P, V1, V2);
-    return new ShuffleVectorInst(NewCmp, UndefValue::get(NewCmp->getType()), M);
-  }
-  return nullptr;
-}
-
-Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
-  bool Changed = false;
-  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-  unsigned Op0Cplxity = getComplexity(Op0);
-  unsigned Op1Cplxity = getComplexity(Op1);
-
-  /// Orders the operands of the compare so that they are listed from most
-  /// complex to least complex.  This puts constants before unary operators,
-  /// before binary operators.
-  if (Op0Cplxity < Op1Cplxity ||
-      (Op0Cplxity == Op1Cplxity && swapMayExposeCSEOpportunities(Op0, Op1))) {
-    I.swapOperands();
-    std::swap(Op0, Op1);
-    Changed = true;
-  }
-
-  if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1,
-                                  SQ.getWithInstruction(&I)))
-    return replaceInstUsesWith(I, V);
-
-  // Comparing -val or val with non-zero is the same as just comparing val
-  // ie, abs(val) != 0 -> val != 0
-  if (I.getPredicate() == ICmpInst::ICMP_NE && match(Op1, m_Zero())) {
-    Value *Cond, *SelectTrue, *SelectFalse;
-    if (match(Op0, m_Select(m_Value(Cond), m_Value(SelectTrue),
-                            m_Value(SelectFalse)))) {
-      if (Value *V = dyn_castNegVal(SelectTrue)) {
-        if (V == SelectFalse)
-          return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
-      }
-      else if (Value *V = dyn_castNegVal(SelectFalse)) {
-        if (V == SelectTrue)
-          return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
-      }
-    }
-  }
-
-  if (Op0->getType()->isIntOrIntVectorTy(1))
-    if (Instruction *Res = canonicalizeICmpBool(I, Builder))
-      return Res;
-
-  if (ICmpInst *NewICmp = canonicalizeCmpWithConstant(I))
-    return NewICmp;
-
-  if (Instruction *Res = foldICmpWithConstant(I))
-    return Res;
-
-  if (Instruction *Res = foldICmpWithDominatingICmp(I))
-    return Res;
-
-  if (Instruction *Res = foldICmpUsingKnownBits(I))
-    return Res;
-
-  // Test if the ICmpInst instruction is used exclusively by a select as
-  // part of a minimum or maximum operation. If so, refrain from doing
-  // any other folding. This helps out other analyses which understand
-  // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
-  // and CodeGen. And in this case, at least one of the comparison
-  // operands has at least one user besides the compare (the select),
-  // which would often largely negate the benefit of folding anyway.
-  //
-  // Do the same for the other patterns recognized by matchSelectPattern.
-  if (I.hasOneUse())
-    if (SelectInst *SI = dyn_cast<SelectInst>(I.user_back())) {
-      Value *A, *B;
-      SelectPatternResult SPR = matchSelectPattern(SI, A, B);
-      if (SPR.Flavor != SPF_UNKNOWN)
-        return nullptr;
-    }
-
-  // Do this after checking for min/max to prevent infinite looping.
-  if (Instruction *Res = foldICmpWithZero(I))
-    return Res;
-
-  // FIXME: We only do this after checking for min/max to prevent infinite
-  // looping caused by a reverse canonicalization of these patterns for min/max.
-  // FIXME: The organization of folds is a mess. These would naturally go into
-  // canonicalizeCmpWithConstant(), but we can't move all of the above folds
-  // down here after the min/max restriction.
-  ICmpInst::Predicate Pred = I.getPredicate();
-  const APInt *C;
-  if (match(Op1, m_APInt(C))) {
-    // For i32: x >u 2147483647 -> x <s 0  -> true if sign bit set
-    if (Pred == ICmpInst::ICMP_UGT && C->isMaxSignedValue()) {
-      Constant *Zero = Constant::getNullValue(Op0->getType());
-      return new ICmpInst(ICmpInst::ICMP_SLT, Op0, Zero);
-    }
-
-    // For i32: x <u 2147483648 -> x >s -1  -> true if sign bit clear
-    if (Pred == ICmpInst::ICMP_ULT && C->isMinSignedValue()) {
-      Constant *AllOnes = Constant::getAllOnesValue(Op0->getType());
-      return new ICmpInst(ICmpInst::ICMP_SGT, Op0, AllOnes);
-    }
-  }
-
-  if (Instruction *Res = foldICmpInstWithConstant(I))
-    return Res;
-
-  if (Instruction *Res = foldICmpInstWithConstantNotInt(I))
-    return Res;
-
-  // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
-  if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0))
-    if (Instruction *NI = foldGEPICmp(GEP, Op1, I.getPredicate(), I))
-      return NI;
-  if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1))
-    if (Instruction *NI = foldGEPICmp(GEP, Op0,
-                           ICmpInst::getSwappedPredicate(I.getPredicate()), I))
-      return NI;
-
-  // Try to optimize equality comparisons against alloca-based pointers.
-  if (Op0->getType()->isPointerTy() && I.isEquality()) {
-    assert(Op1->getType()->isPointerTy() && "Comparing pointer with non-pointer?");
-    if (auto *Alloca = dyn_cast<AllocaInst>(GetUnderlyingObject(Op0, DL)))
-      if (Instruction *New = foldAllocaCmp(I, Alloca, Op1))
-        return New;
-    if (auto *Alloca = dyn_cast<AllocaInst>(GetUnderlyingObject(Op1, DL)))
-      if (Instruction *New = foldAllocaCmp(I, Alloca, Op0))
-        return New;
-  }
-
-  // Zero-equality and sign-bit checks are preserved through sitofp + bitcast.
-  Value *X;
-  if (match(Op0, m_BitCast(m_SIToFP(m_Value(X))))) {
-    // icmp  eq (bitcast (sitofp X)), 0 --> icmp  eq X, 0
-    // icmp  ne (bitcast (sitofp X)), 0 --> icmp  ne X, 0
-    // icmp slt (bitcast (sitofp X)), 0 --> icmp slt X, 0
-    // icmp sgt (bitcast (sitofp X)), 0 --> icmp sgt X, 0
-    if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_SLT ||
-         Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT) &&
-        match(Op1, m_Zero()))
-      return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType()));
-
-    // icmp slt (bitcast (sitofp X)), 1 --> icmp slt X, 1
-    if (Pred == ICmpInst::ICMP_SLT && match(Op1, m_One()))
-      return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), 1));
-
-    // icmp sgt (bitcast (sitofp X)), -1 --> icmp sgt X, -1
-    if (Pred == ICmpInst::ICMP_SGT && match(Op1, m_AllOnes()))
-      return new ICmpInst(Pred, X, ConstantInt::getAllOnesValue(X->getType()));
-  }
-
-  // Zero-equality checks are preserved through unsigned floating-point casts:
-  // icmp eq (bitcast (uitofp X)), 0 --> icmp eq X, 0
-  // icmp ne (bitcast (uitofp X)), 0 --> icmp ne X, 0
-  if (match(Op0, m_BitCast(m_UIToFP(m_Value(X)))))
-    if (I.isEquality() && match(Op1, m_Zero()))
-      return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType()));
-
-  // Test to see if the operands of the icmp are casted versions of other
-  // values.  If the ptr->ptr cast can be stripped off both arguments, we do so
-  // now.
-  if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
-    if (Op0->getType()->isPointerTy() &&
-        (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
-      // We keep moving the cast from the left operand over to the right
-      // operand, where it can often be eliminated completely.
-      Op0 = CI->getOperand(0);
-
-      // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
-      // so eliminate it as well.
-      if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
-        Op1 = CI2->getOperand(0);
-
-      // If Op1 is a constant, we can fold the cast into the constant.
-      if (Op0->getType() != Op1->getType()) {
-        if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
-          Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
-        } else {
-          // Otherwise, cast the RHS right before the icmp
-          Op1 = Builder.CreateBitCast(Op1, Op0->getType());
-        }
-      }
-      return new ICmpInst(I.getPredicate(), Op0, Op1);
-    }
-  }
-
-  if (isa<CastInst>(Op0)) {
-    // Handle the special case of: icmp (cast bool to X), <cst>
-    // This comes up when you have code like
-    //   int X = A < B;
-    //   if (X) ...
-    // For generality, we handle any zero-extension of any operand comparison
-    // with a constant or another cast from the same type.
-    if (isa<Constant>(Op1) || isa<CastInst>(Op1))
-      if (Instruction *R = foldICmpWithCastAndCast(I))
-        return R;
-  }
-
-  if (Instruction *Res = foldICmpBinOp(I))
-    return Res;
-
-  if (Instruction *Res = foldICmpWithMinMax(I))
-    return Res;
-
-  {
-    Value *A, *B;
-    // Transform (A & ~B) == 0 --> (A & B) != 0
-    // and       (A & ~B) != 0 --> (A & B) == 0
-    // if A is a power of 2.
-    if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) &&
-        match(Op1, m_Zero()) &&
-        isKnownToBeAPowerOfTwo(A, false, 0, &I) && I.isEquality())
-      return new ICmpInst(I.getInversePredicate(), Builder.CreateAnd(A, B),
-                          Op1);
-
-    // ~X < ~Y --> Y < X
-    // ~X < C -->  X > ~C
-    if (match(Op0, m_Not(m_Value(A)))) {
-      if (match(Op1, m_Not(m_Value(B))))
-        return new ICmpInst(I.getPredicate(), B, A);
-
-      const APInt *C;
-      if (match(Op1, m_APInt(C)))
-        return new ICmpInst(I.getSwappedPredicate(), A,
-                            ConstantInt::get(Op1->getType(), ~(*C)));
-    }
-
-    Instruction *AddI = nullptr;
-    if (match(&I, m_UAddWithOverflow(m_Value(A), m_Value(B),
-                                     m_Instruction(AddI))) &&
-        isa<IntegerType>(A->getType())) {
-      Value *Result;
-      Constant *Overflow;
-      if (OptimizeOverflowCheck(OCF_UNSIGNED_ADD, A, B, *AddI, Result,
-                                Overflow)) {
-        replaceInstUsesWith(*AddI, Result);
-        return replaceInstUsesWith(I, Overflow);
-      }
-    }
-
-    // (zext a) * (zext b)  --> llvm.umul.with.overflow.
-    if (match(Op0, m_Mul(m_ZExt(m_Value(A)), m_ZExt(m_Value(B))))) {
-      if (Instruction *R = processUMulZExtIdiom(I, Op0, Op1, *this))
-        return R;
-    }
-    if (match(Op1, m_Mul(m_ZExt(m_Value(A)), m_ZExt(m_Value(B))))) {
-      if (Instruction *R = processUMulZExtIdiom(I, Op1, Op0, *this))
-        return R;
-    }
-  }
-
-  if (Instruction *Res = foldICmpEquality(I))
-    return Res;
-
-  // The 'cmpxchg' instruction returns an aggregate containing the old value and
-  // an i1 which indicates whether or not we successfully did the swap.
-  //
-  // Replace comparisons between the old value and the expected value with the
-  // indicator that 'cmpxchg' returns.
-  //
-  // N.B.  This transform is only valid when the 'cmpxchg' is not permitted to
-  // spuriously fail.  In those cases, the old value may equal the expected
-  // value but it is possible for the swap to not occur.
-  if (I.getPredicate() == ICmpInst::ICMP_EQ)
-    if (auto *EVI = dyn_cast<ExtractValueInst>(Op0))
-      if (auto *ACXI = dyn_cast<AtomicCmpXchgInst>(EVI->getAggregateOperand()))
-        if (EVI->getIndices()[0] == 0 && ACXI->getCompareOperand() == Op1 &&
-            !ACXI->isWeak())
-          return ExtractValueInst::Create(ACXI, 1);
-
-  {
-    Value *X;
-    const APInt *C;
-    // icmp X+Cst, X
-    if (match(Op0, m_Add(m_Value(X), m_APInt(C))) && Op1 == X)
-      return foldICmpAddOpConst(X, *C, I.getPredicate());
-
-    // icmp X, X+Cst
-    if (match(Op1, m_Add(m_Value(X), m_APInt(C))) && Op0 == X)
-      return foldICmpAddOpConst(X, *C, I.getSwappedPredicate());
-  }
-
-  if (Instruction *Res = foldICmpWithHighBitMask(I, Builder))
-    return Res;
-
-  if (I.getType()->isVectorTy())
-    if (Instruction *Res = foldVectorCmp(I, Builder))
-      return Res;
-
-  return Changed ? &I : nullptr;
-}
-
-/// Fold fcmp ([us]itofp x, cst) if possible.
-Instruction *InstCombiner::foldFCmpIntToFPConst(FCmpInst &I, Instruction *LHSI,
-                                                Constant *RHSC) {
-  if (!isa<ConstantFP>(RHSC)) return nullptr;
-  const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
-
-  // Get the width of the mantissa.  We don't want to hack on conversions that
-  // might lose information from the integer, e.g. "i64 -> float"
-  int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
-  if (MantissaWidth == -1) return nullptr;  // Unknown.
-
-  IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
-
-  bool LHSUnsigned = isa<UIToFPInst>(LHSI);
-
-  if (I.isEquality()) {
-    FCmpInst::Predicate P = I.getPredicate();
-    bool IsExact = false;
-    APSInt RHSCvt(IntTy->getBitWidth(), LHSUnsigned);
-    RHS.convertToInteger(RHSCvt, APFloat::rmNearestTiesToEven, &IsExact);
-
-    // If the floating point constant isn't an integer value, we know if we will
-    // ever compare equal / not equal to it.
-    if (!IsExact) {
-      // TODO: Can never be -0.0 and other non-representable values
-      APFloat RHSRoundInt(RHS);
-      RHSRoundInt.roundToIntegral(APFloat::rmNearestTiesToEven);
-      if (RHS.compare(RHSRoundInt) != APFloat::cmpEqual) {
-        if (P == FCmpInst::FCMP_OEQ || P == FCmpInst::FCMP_UEQ)
-          return replaceInstUsesWith(I, Builder.getFalse());
-
-        assert(P == FCmpInst::FCMP_ONE || P == FCmpInst::FCMP_UNE);
-        return replaceInstUsesWith(I, Builder.getTrue());
-      }
-    }
-
-    // TODO: If the constant is exactly representable, is it always OK to do
-    // equality compares as integer?
-  }
-
-  // Check to see that the input is converted from an integer type that is small
-  // enough that preserves all bits.  TODO: check here for "known" sign bits.
-  // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
-  unsigned InputSize = IntTy->getScalarSizeInBits();
-
-  // Following test does NOT adjust InputSize downwards for signed inputs,
-  // because the most negative value still requires all the mantissa bits
-  // to distinguish it from one less than that value.
-  if ((int)InputSize > MantissaWidth) {
-    // Conversion would lose accuracy. Check if loss can impact comparison.
-    int Exp = ilogb(RHS);
-    if (Exp == APFloat::IEK_Inf) {
-      int MaxExponent = ilogb(APFloat::getLargest(RHS.getSemantics()));
-      if (MaxExponent < (int)InputSize - !LHSUnsigned)
-        // Conversion could create infinity.
-        return nullptr;
-    } else {
-      // Note that if RHS is zero or NaN, then Exp is negative
-      // and first condition is trivially false.
-      if (MantissaWidth <= Exp && Exp <= (int)InputSize - !LHSUnsigned)
-        // Conversion could affect comparison.
-        return nullptr;
-    }
-  }
-
-  // Otherwise, we can potentially simplify the comparison.  We know that it
-  // will always come through as an integer value and we know the constant is
-  // not a NAN (it would have been previously simplified).
-  assert(!RHS.isNaN() && "NaN comparison not already folded!");
-
-  ICmpInst::Predicate Pred;
-  switch (I.getPredicate()) {
-  default: llvm_unreachable("Unexpected predicate!");
-  case FCmpInst::FCMP_UEQ:
-  case FCmpInst::FCMP_OEQ:
-    Pred = ICmpInst::ICMP_EQ;
-    break;
-  case FCmpInst::FCMP_UGT:
-  case FCmpInst::FCMP_OGT:
-    Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
-    break;
-  case FCmpInst::FCMP_UGE:
-  case FCmpInst::FCMP_OGE:
-    Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
-    break;
-  case FCmpInst::FCMP_ULT:
-  case FCmpInst::FCMP_OLT:
-    Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
-    break;
-  case FCmpInst::FCMP_ULE:
-  case FCmpInst::FCMP_OLE:
-    Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
-    break;
-  case FCmpInst::FCMP_UNE:
-  case FCmpInst::FCMP_ONE:
-    Pred = ICmpInst::ICMP_NE;
-    break;
-  case FCmpInst::FCMP_ORD:
-    return replaceInstUsesWith(I, Builder.getTrue());
-  case FCmpInst::FCMP_UNO:
-    return replaceInstUsesWith(I, Builder.getFalse());
-  }
-
-  // Now we know that the APFloat is a normal number, zero or inf.
-
-  // See if the FP constant is too large for the integer.  For example,
-  // comparing an i8 to 300.0.
-  unsigned IntWidth = IntTy->getScalarSizeInBits();
-
-  if (!LHSUnsigned) {
-    // If the RHS value is > SignedMax, fold the comparison.  This handles +INF
-    // and large values.
-    APFloat SMax(RHS.getSemantics());
-    SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
-                          APFloat::rmNearestTiesToEven);
-    if (SMax.compare(RHS) == APFloat::cmpLessThan) {  // smax < 13123.0
-      if (Pred == ICmpInst::ICMP_NE  || Pred == ICmpInst::ICMP_SLT ||
-          Pred == ICmpInst::ICMP_SLE)
-        return replaceInstUsesWith(I, Builder.getTrue());
-      return replaceInstUsesWith(I, Builder.getFalse());
-    }
-  } else {
-    // If the RHS value is > UnsignedMax, fold the comparison. This handles
-    // +INF and large values.
-    APFloat UMax(RHS.getSemantics());
-    UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
-                          APFloat::rmNearestTiesToEven);
-    if (UMax.compare(RHS) == APFloat::cmpLessThan) {  // umax < 13123.0
-      if (Pred == ICmpInst::ICMP_NE  || Pred == ICmpInst::ICMP_ULT ||
-          Pred == ICmpInst::ICMP_ULE)
-        return replaceInstUsesWith(I, Builder.getTrue());
-      return replaceInstUsesWith(I, Builder.getFalse());
-    }
-  }
-
-  if (!LHSUnsigned) {
-    // See if the RHS value is < SignedMin.
-    APFloat SMin(RHS.getSemantics());
-    SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
-                          APFloat::rmNearestTiesToEven);
-    if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
-      if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
-          Pred == ICmpInst::ICMP_SGE)
-        return replaceInstUsesWith(I, Builder.getTrue());
-      return replaceInstUsesWith(I, Builder.getFalse());
-    }
-  } else {
-    // See if the RHS value is < UnsignedMin.
-    APFloat SMin(RHS.getSemantics());
-    SMin.convertFromAPInt(APInt::getMinValue(IntWidth), true,
-                          APFloat::rmNearestTiesToEven);
-    if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // umin > 12312.0
-      if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_UGT ||
-          Pred == ICmpInst::ICMP_UGE)
-        return replaceInstUsesWith(I, Builder.getTrue());
-      return replaceInstUsesWith(I, Builder.getFalse());
-    }
-  }
-
-  // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
-  // [0, UMAX], but it may still be fractional.  See if it is fractional by
-  // casting the FP value to the integer value and back, checking for equality.
-  // Don't do this for zero, because -0.0 is not fractional.
-  Constant *RHSInt = LHSUnsigned
-    ? ConstantExpr::getFPToUI(RHSC, IntTy)
-    : ConstantExpr::getFPToSI(RHSC, IntTy);
-  if (!RHS.isZero()) {
-    bool Equal = LHSUnsigned
-      ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
-      : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
-    if (!Equal) {
-      // If we had a comparison against a fractional value, we have to adjust
-      // the compare predicate and sometimes the value.  RHSC is rounded towards
-      // zero at this point.
-      switch (Pred) {
-      default: llvm_unreachable("Unexpected integer comparison!");
-      case ICmpInst::ICMP_NE:  // (float)int != 4.4   --> true
-        return replaceInstUsesWith(I, Builder.getTrue());
-      case ICmpInst::ICMP_EQ:  // (float)int == 4.4   --> false
-        return replaceInstUsesWith(I, Builder.getFalse());
-      case ICmpInst::ICMP_ULE:
-        // (float)int <= 4.4   --> int <= 4
-        // (float)int <= -4.4  --> false
-        if (RHS.isNegative())
-          return replaceInstUsesWith(I, Builder.getFalse());
-        break;
-      case ICmpInst::ICMP_SLE:
-        // (float)int <= 4.4   --> int <= 4
-        // (float)int <= -4.4  --> int < -4
-        if (RHS.isNegative())
-          Pred = ICmpInst::ICMP_SLT;
-        break;
-      case ICmpInst::ICMP_ULT:
-        // (float)int < -4.4   --> false
-        // (float)int < 4.4    --> int <= 4
-        if (RHS.isNegative())
-          return replaceInstUsesWith(I, Builder.getFalse());
-        Pred = ICmpInst::ICMP_ULE;
-        break;
-      case ICmpInst::ICMP_SLT:
-        // (float)int < -4.4   --> int < -4
-        // (float)int < 4.4    --> int <= 4
-        if (!RHS.isNegative())
-          Pred = ICmpInst::ICMP_SLE;
-        break;
-      case ICmpInst::ICMP_UGT:
-        // (float)int > 4.4    --> int > 4
-        // (float)int > -4.4   --> true
-        if (RHS.isNegative())
-          return replaceInstUsesWith(I, Builder.getTrue());
-        break;
-      case ICmpInst::ICMP_SGT:
-        // (float)int > 4.4    --> int > 4
-        // (float)int > -4.4   --> int >= -4
-        if (RHS.isNegative())
-          Pred = ICmpInst::ICMP_SGE;
-        break;
-      case ICmpInst::ICMP_UGE:
-        // (float)int >= -4.4   --> true
-        // (float)int >= 4.4    --> int > 4
-        if (RHS.isNegative())
-          return replaceInstUsesWith(I, Builder.getTrue());
-        Pred = ICmpInst::ICMP_UGT;
-        break;
-      case ICmpInst::ICMP_SGE:
-        // (float)int >= -4.4   --> int >= -4
-        // (float)int >= 4.4    --> int > 4
-        if (!RHS.isNegative())
-          Pred = ICmpInst::ICMP_SGT;
-        break;
-      }
-    }
-  }
-
-  // Lower this FP comparison into an appropriate integer version of the
-  // comparison.
-  return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
-}
-
-/// Fold (C / X) < 0.0 --> X < 0.0 if possible. Swap predicate if necessary.
-static Instruction *foldFCmpReciprocalAndZero(FCmpInst &I, Instruction *LHSI,
-                                              Constant *RHSC) {
-  // When C is not 0.0 and infinities are not allowed:
-  // (C / X) < 0.0 is a sign-bit test of X
-  // (C / X) < 0.0 --> X < 0.0 (if C is positive)
-  // (C / X) < 0.0 --> X > 0.0 (if C is negative, swap the predicate)
-  //
-  // Proof:
-  // Multiply (C / X) < 0.0 by X * X / C.
-  // - X is non zero, if it is the flag 'ninf' is violated.
-  // - C defines the sign of X * X * C. Thus it also defines whether to swap
-  //   the predicate. C is also non zero by definition.
-  //
-  // Thus X * X / C is non zero and the transformation is valid. [qed]
-
-  FCmpInst::Predicate Pred = I.getPredicate();
-
-  // Check that predicates are valid.
-  if ((Pred != FCmpInst::FCMP_OGT) && (Pred != FCmpInst::FCMP_OLT) &&
-      (Pred != FCmpInst::FCMP_OGE) && (Pred != FCmpInst::FCMP_OLE))
-    return nullptr;
-
-  // Check that RHS operand is zero.
-  if (!match(RHSC, m_AnyZeroFP()))
-    return nullptr;
-
-  // Check fastmath flags ('ninf').
-  if (!LHSI->hasNoInfs() || !I.hasNoInfs())
-    return nullptr;
-
-  // Check the properties of the dividend. It must not be zero to avoid a
-  // division by zero (see Proof).
-  const APFloat *C;
-  if (!match(LHSI->getOperand(0), m_APFloat(C)))
-    return nullptr;
-
-  if (C->isZero())
-    return nullptr;
-
-  // Get swapped predicate if necessary.
-  if (C->isNegative())
-    Pred = I.getSwappedPredicate();
-
-  return new FCmpInst(Pred, LHSI->getOperand(1), RHSC, "", &I);
-}
-
-/// Optimize fabs(X) compared with zero.
-static Instruction *foldFabsWithFcmpZero(FCmpInst &I) {
-  Value *X;
-  if (!match(I.getOperand(0), m_Intrinsic<Intrinsic::fabs>(m_Value(X))) ||
-      !match(I.getOperand(1), m_PosZeroFP()))
-    return nullptr;
-
-  auto replacePredAndOp0 = [](FCmpInst *I, FCmpInst::Predicate P, Value *X) {
-    I->setPredicate(P);
-    I->setOperand(0, X);
-    return I;
-  };
-
-  switch (I.getPredicate()) {
-  case FCmpInst::FCMP_UGE:
-  case FCmpInst::FCMP_OLT:
-    // fabs(X) >= 0.0 --> true
-    // fabs(X) <  0.0 --> false
-    llvm_unreachable("fcmp should have simplified");
-
-  case FCmpInst::FCMP_OGT:
-    // fabs(X) > 0.0 --> X != 0.0
-    return replacePredAndOp0(&I, FCmpInst::FCMP_ONE, X);
-
-  case FCmpInst::FCMP_UGT:
-    // fabs(X) u> 0.0 --> X u!= 0.0
-    return replacePredAndOp0(&I, FCmpInst::FCMP_UNE, X);
-
-  case FCmpInst::FCMP_OLE:
-    // fabs(X) <= 0.0 --> X == 0.0
-    return replacePredAndOp0(&I, FCmpInst::FCMP_OEQ, X);
-
-  case FCmpInst::FCMP_ULE:
-    // fabs(X) u<= 0.0 --> X u== 0.0
-    return replacePredAndOp0(&I, FCmpInst::FCMP_UEQ, X);
-
-  case FCmpInst::FCMP_OGE:
-    // fabs(X) >= 0.0 --> !isnan(X)
-    assert(!I.hasNoNaNs() && "fcmp should have simplified");
-    return replacePredAndOp0(&I, FCmpInst::FCMP_ORD, X);
-
-  case FCmpInst::FCMP_ULT:
-    // fabs(X) u< 0.0 --> isnan(X)
-    assert(!I.hasNoNaNs() && "fcmp should have simplified");
-    return replacePredAndOp0(&I, FCmpInst::FCMP_UNO, X);
-
-  case FCmpInst::FCMP_OEQ:
-  case FCmpInst::FCMP_UEQ:
-  case FCmpInst::FCMP_ONE:
-  case FCmpInst::FCMP_UNE:
-  case FCmpInst::FCMP_ORD:
-  case FCmpInst::FCMP_UNO:
-    // Look through the fabs() because it doesn't change anything but the sign.
-    // fabs(X) == 0.0 --> X == 0.0,
-    // fabs(X) != 0.0 --> X != 0.0
-    // isnan(fabs(X)) --> isnan(X)
-    // !isnan(fabs(X) --> !isnan(X)
-    return replacePredAndOp0(&I, I.getPredicate(), X);
-
-  default:
-    return nullptr;
-  }
-}
-
-Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
-  bool Changed = false;
-
-  /// Orders the operands of the compare so that they are listed from most
-  /// complex to least complex.  This puts constants before unary operators,
-  /// before binary operators.
-  if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
-    I.swapOperands();
-    Changed = true;
-  }
-
-  const CmpInst::Predicate Pred = I.getPredicate();
-  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-  if (Value *V = SimplifyFCmpInst(Pred, Op0, Op1, I.getFastMathFlags(),
-                                  SQ.getWithInstruction(&I)))
-    return replaceInstUsesWith(I, V);
-
-  // Simplify 'fcmp pred X, X'
-  if (Op0 == Op1) {
-    switch (Pred) {
-      default: break;
-    case FCmpInst::FCMP_UNO:    // True if unordered: isnan(X) | isnan(Y)
-    case FCmpInst::FCMP_ULT:    // True if unordered or less than
-    case FCmpInst::FCMP_UGT:    // True if unordered or greater than
-    case FCmpInst::FCMP_UNE:    // True if unordered or not equal
-      // Canonicalize these to be 'fcmp uno %X, 0.0'.
-      I.setPredicate(FCmpInst::FCMP_UNO);
-      I.setOperand(1, Constant::getNullValue(Op0->getType()));
-      return &I;
-
-    case FCmpInst::FCMP_ORD:    // True if ordered (no nans)
-    case FCmpInst::FCMP_OEQ:    // True if ordered and equal
-    case FCmpInst::FCMP_OGE:    // True if ordered and greater than or equal
-    case FCmpInst::FCMP_OLE:    // True if ordered and less than or equal
-      // Canonicalize these to be 'fcmp ord %X, 0.0'.
-      I.setPredicate(FCmpInst::FCMP_ORD);
-      I.setOperand(1, Constant::getNullValue(Op0->getType()));
-      return &I;
-    }
-  }
-
-  // If we're just checking for a NaN (ORD/UNO) and have a non-NaN operand,
-  // then canonicalize the operand to 0.0.
-  if (Pred == CmpInst::FCMP_ORD || Pred == CmpInst::FCMP_UNO) {
-    if (!match(Op0, m_PosZeroFP()) && isKnownNeverNaN(Op0, &TLI)) {
-      I.setOperand(0, ConstantFP::getNullValue(Op0->getType()));
-      return &I;
-    }
-    if (!match(Op1, m_PosZeroFP()) && isKnownNeverNaN(Op1, &TLI)) {
-      I.setOperand(1, ConstantFP::getNullValue(Op0->getType()));
-      return &I;
-    }
-  }
-
-  // Test if the FCmpInst instruction is used exclusively by a select as
-  // part of a minimum or maximum operation. If so, refrain from doing
-  // any other folding. This helps out other analyses which understand
-  // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
-  // and CodeGen. And in this case, at least one of the comparison
-  // operands has at least one user besides the compare (the select),
-  // which would often largely negate the benefit of folding anyway.
-  if (I.hasOneUse())
-    if (SelectInst *SI = dyn_cast<SelectInst>(I.user_back())) {
-      Value *A, *B;
-      SelectPatternResult SPR = matchSelectPattern(SI, A, B);
-      if (SPR.Flavor != SPF_UNKNOWN)
-        return nullptr;
-    }
-
-  // The sign of 0.0 is ignored by fcmp, so canonicalize to +0.0:
-  // fcmp Pred X, -0.0 --> fcmp Pred X, 0.0
-  if (match(Op1, m_AnyZeroFP()) && !match(Op1, m_PosZeroFP())) {
-    I.setOperand(1, ConstantFP::getNullValue(Op1->getType()));
-    return &I;
-  }
-
-  // Handle fcmp with instruction LHS and constant RHS.
-  Instruction *LHSI;
-  Constant *RHSC;
-  if (match(Op0, m_Instruction(LHSI)) && match(Op1, m_Constant(RHSC))) {
-    switch (LHSI->getOpcode()) {
-    case Instruction::PHI:
-      // Only fold fcmp into the PHI if the phi and fcmp are in the same
-      // block.  If in the same block, we're encouraging jump threading.  If
-      // not, we are just pessimizing the code by making an i1 phi.
-      if (LHSI->getParent() == I.getParent())
-        if (Instruction *NV = foldOpIntoPhi(I, cast<PHINode>(LHSI)))
-          return NV;
-      break;
-    case Instruction::SIToFP:
-    case Instruction::UIToFP:
-      if (Instruction *NV = foldFCmpIntToFPConst(I, LHSI, RHSC))
-        return NV;
-      break;
-    case Instruction::FDiv:
-      if (Instruction *NV = foldFCmpReciprocalAndZero(I, LHSI, RHSC))
-        return NV;
-      break;
-    case Instruction::Load:
-      if (auto *GEP = dyn_cast<GetElementPtrInst>(LHSI->getOperand(0)))
-        if (auto *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
-          if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
-              !cast<LoadInst>(LHSI)->isVolatile())
-            if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, I))
-              return Res;
-      break;
-  }
-  }
-
-  if (Instruction *R = foldFabsWithFcmpZero(I))
-    return R;
-
-  Value *X, *Y;
-  if (match(Op0, m_FNeg(m_Value(X)))) {
-    // fcmp pred (fneg X), (fneg Y) -> fcmp swap(pred) X, Y
-    if (match(Op1, m_FNeg(m_Value(Y))))
-      return new FCmpInst(I.getSwappedPredicate(), X, Y, "", &I);
-
-    // fcmp pred (fneg X), C --> fcmp swap(pred) X, -C
-    Constant *C;
-    if (match(Op1, m_Constant(C))) {
-      Constant *NegC = ConstantExpr::getFNeg(C);
-      return new FCmpInst(I.getSwappedPredicate(), X, NegC, "", &I);
-    }
-  }
-
-  if (match(Op0, m_FPExt(m_Value(X)))) {
-    // fcmp (fpext X), (fpext Y) -> fcmp X, Y
-    if (match(Op1, m_FPExt(m_Value(Y))) && X->getType() == Y->getType())
-      return new FCmpInst(Pred, X, Y, "", &I);
-
-    // fcmp (fpext X), C -> fcmp X, (fptrunc C) if fptrunc is lossless
-    const APFloat *C;
-    if (match(Op1, m_APFloat(C))) {
-      const fltSemantics &FPSem =
-          X->getType()->getScalarType()->getFltSemantics();
-      bool Lossy;
-      APFloat TruncC = *C;
-      TruncC.convert(FPSem, APFloat::rmNearestTiesToEven, &Lossy);
-
-      // Avoid lossy conversions and denormals.
-      // Zero is a special case that's OK to convert.
-      APFloat Fabs = TruncC;
-      Fabs.clearSign();
-      if (!Lossy &&
-          ((Fabs.compare(APFloat::getSmallestNormalized(FPSem)) !=
-            APFloat::cmpLessThan) || Fabs.isZero())) {
-        Constant *NewC = ConstantFP::get(X->getType(), TruncC);
-        return new FCmpInst(Pred, X, NewC, "", &I);
-      }
-    }
-  }
-
-  if (I.getType()->isVectorTy())
-    if (Instruction *Res = foldVectorCmp(I, Builder))
-      return Res;
-
-  return Changed ? &I : nullptr;
-}