/build/llvm-toolchain-snapshot-10~svn372306/include/llvm/Analysis/ValueTracking.h

Bug Summary

File:	include/llvm/Analysis/ValueTracking.h
Warning:	line 626, column 5 Assigned value is garbage or undefined

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name ValueTracking.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -mframe-pointer=none -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-10/lib/clang/10.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-10~svn372306/build-llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis -I /build/llvm-toolchain-snapshot-10~svn372306/build-llvm/include -I /build/llvm-toolchain-snapshot-10~svn372306/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-10/lib/clang/10.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-10~svn372306/build-llvm/lib/Analysis -fdebug-prefix-map=/build/llvm-toolchain-snapshot-10~svn372306=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2019-09-19-172240-30738-1 -x c++ /build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp

/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp

→

1//===- ValueTracking.cpp - Walk computations to compute properties --------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains routines that help analyze properties that chains of
10// computations have.
11//
12//===----------------------------------------------------------------------===//

14#include "llvm/Analysis/ValueTracking.h"
15#include "llvm/ADT/APFloat.h"
16#include "llvm/ADT/APInt.h"
17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/None.h"
19#include "llvm/ADT/Optional.h"
20#include "llvm/ADT/STLExtras.h"
21#include "llvm/ADT/SmallPtrSet.h"
22#include "llvm/ADT/SmallSet.h"
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/ADT/StringRef.h"
25#include "llvm/ADT/iterator_range.h"
26#include "llvm/Analysis/AliasAnalysis.h"
27#include "llvm/Analysis/AssumptionCache.h"
28#include "llvm/Analysis/GuardUtils.h"
29#include "llvm/Analysis/InstructionSimplify.h"
30#include "llvm/Analysis/Loads.h"
31#include "llvm/Analysis/LoopInfo.h"
32#include "llvm/Analysis/OptimizationRemarkEmitter.h"
33#include "llvm/Analysis/TargetLibraryInfo.h"
34#include "llvm/IR/Argument.h"
35#include "llvm/IR/Attributes.h"
36#include "llvm/IR/BasicBlock.h"
37#include "llvm/IR/CallSite.h"
38#include "llvm/IR/Constant.h"
39#include "llvm/IR/ConstantRange.h"
40#include "llvm/IR/Constants.h"
41#include "llvm/IR/DerivedTypes.h"
42#include "llvm/IR/DiagnosticInfo.h"
43#include "llvm/IR/Dominators.h"
44#include "llvm/IR/Function.h"
45#include "llvm/IR/GetElementPtrTypeIterator.h"
46#include "llvm/IR/GlobalAlias.h"
47#include "llvm/IR/GlobalValue.h"
48#include "llvm/IR/GlobalVariable.h"
49#include "llvm/IR/InstrTypes.h"
50#include "llvm/IR/Instruction.h"
51#include "llvm/IR/Instructions.h"
52#include "llvm/IR/IntrinsicInst.h"
53#include "llvm/IR/Intrinsics.h"
54#include "llvm/IR/LLVMContext.h"
55#include "llvm/IR/Metadata.h"
56#include "llvm/IR/Module.h"
57#include "llvm/IR/Operator.h"
58#include "llvm/IR/PatternMatch.h"
59#include "llvm/IR/Type.h"
60#include "llvm/IR/User.h"
61#include "llvm/IR/Value.h"
62#include "llvm/Support/Casting.h"
63#include "llvm/Support/CommandLine.h"
64#include "llvm/Support/Compiler.h"
65#include "llvm/Support/ErrorHandling.h"
66#include "llvm/Support/KnownBits.h"
67#include "llvm/Support/MathExtras.h"
68#include <algorithm>
69#include <array>
70#include <cassert>
71#include <cstdint>
72#include <iterator>
73#include <utility>

75using namespace llvm;
76using namespace llvm::PatternMatch;

78const unsigned MaxDepth = 6;

80// Controls the number of uses of the value searched for possible
81// dominating comparisons.
82static cl::opt<unsigned> DomConditionsMaxUses("dom-conditions-max-uses",
                                            cl::Hidden, cl::init(20));

85/// Returns the bitwidth of the given scalar or pointer type. For vector types,
86/// returns the element type's bitwidth.
87static unsigned getBitWidth(Type *Ty, const DataLayout &DL) {
if (unsigned BitWidth = Ty->getScalarSizeInBits())
  return BitWidth;

return DL.getIndexTypeSizeInBits(Ty);
92}

94namespace {

96// Simplifying using an assume can only be done in a particular control-flow
97// context (the context instruction provides that context). If an assume and
98// the context instruction are not in the same block then the DT helps in
99// figuring out if we can use it.
100struct Query {
const DataLayout &DL;
AssumptionCache *AC;
const Instruction *CxtI;
const DominatorTree *DT;

// Unlike the other analyses, this may be a nullptr because not all clients
// provide it currently.
OptimizationRemarkEmitter *ORE;

/// Set of assumptions that should be excluded from further queries.
/// This is because of the potential for mutual recursion to cause
/// computeKnownBits to repeatedly visit the same assume intrinsic. The
/// classic case of this is assume(x = y), which will attempt to determine
/// bits in x from bits in y, which will attempt to determine bits in y from
/// bits in x, etc. Regarding the mutual recursion, computeKnownBits can call
/// isKnownNonZero, which calls computeKnownBits and isKnownToBeAPowerOfTwo
/// (all of which can call computeKnownBits), and so on.
std::array<const Value *, MaxDepth> Excluded;

/// If true, it is safe to use metadata during simplification.
InstrInfoQuery IIQ;

unsigned NumExcluded = 0;

Query(const DataLayout &DL, AssumptionCache *AC, const Instruction *CxtI,
      const DominatorTree *DT, bool UseInstrInfo,
      OptimizationRemarkEmitter *ORE = nullptr)
    : DL(DL), AC(AC), CxtI(CxtI), DT(DT), ORE(ORE), IIQ(UseInstrInfo) {}

Query(const Query &Q, const Value *NewExcl)
    : DL(Q.DL), AC(Q.AC), CxtI(Q.CxtI), DT(Q.DT), ORE(Q.ORE), IIQ(Q.IIQ),
      NumExcluded(Q.NumExcluded) {
  Excluded = Q.Excluded;
  Excluded[NumExcluded++] = NewExcl;
  assert(NumExcluded <= Excluded.size())((NumExcluded <= Excluded.size()) ? static_cast<void>
 (0) : __assert_fail ("NumExcluded <= Excluded.size()", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 135, __PRETTY_FUNCTION__));
}

bool isExcluded(const Value *Value) const {
  if (NumExcluded == 0)
    return false;
  auto End = Excluded.begin() + NumExcluded;
  return std::find(Excluded.begin(), End, Value) != End;
}
144};

146} // end anonymous namespace

148// Given the provided Value and, potentially, a context instruction, return
149// the preferred context instruction (if any).
150static const Instruction *safeCxtI(const Value *V, const Instruction *CxtI) {
// If we've been provided with a context instruction, then use that (provided
// it has been inserted).
if (CxtI && CxtI->getParent())
  return CxtI;

// If the value is really an already-inserted instruction, then use that.
CxtI = dyn_cast<Instruction>(V);
if (CxtI && CxtI->getParent())
  return CxtI;

return nullptr;
162}

164static void computeKnownBits(const Value *V, KnownBits &Known,
                           unsigned Depth, const Query &Q);

167void llvm::computeKnownBits(const Value *V, KnownBits &Known,
                          const DataLayout &DL, unsigned Depth,
                          AssumptionCache *AC, const Instruction *CxtI,
                          const DominatorTree *DT,
                          OptimizationRemarkEmitter *ORE, bool UseInstrInfo) {
::computeKnownBits(V, Known, Depth,
                   Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE));
174}

176static KnownBits computeKnownBits(const Value *V, unsigned Depth,
                                const Query &Q);

179KnownBits llvm::computeKnownBits(const Value *V, const DataLayout &DL,
                               unsigned Depth, AssumptionCache *AC,
                               const Instruction *CxtI,
                               const DominatorTree *DT,
                               OptimizationRemarkEmitter *ORE,
                               bool UseInstrInfo) {
return ::computeKnownBits(
    V, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE));
187}

189bool llvm::haveNoCommonBitsSet(const Value *LHS, const Value *RHS,
                             const DataLayout &DL, AssumptionCache *AC,
                             const Instruction *CxtI, const DominatorTree *DT,
                             bool UseInstrInfo) {
assert(LHS->getType() == RHS->getType() &&((LHS->getType() == RHS->getType() && "LHS and RHS should have the same type"
) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"LHS and RHS should have the same type\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 194, __PRETTY_FUNCTION__))
       "LHS and RHS should have the same type")((LHS->getType() == RHS->getType() && "LHS and RHS should have the same type"
) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"LHS and RHS should have the same type\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 194, __PRETTY_FUNCTION__));
assert(LHS->getType()->isIntOrIntVectorTy() &&((LHS->getType()->isIntOrIntVectorTy() && "LHS and RHS should be integers"
) ? static_cast<void> (0) : __assert_fail ("LHS->getType()->isIntOrIntVectorTy() && \"LHS and RHS should be integers\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 196, __PRETTY_FUNCTION__))
       "LHS and RHS should be integers")((LHS->getType()->isIntOrIntVectorTy() && "LHS and RHS should be integers"
) ? static_cast<void> (0) : __assert_fail ("LHS->getType()->isIntOrIntVectorTy() && \"LHS and RHS should be integers\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 196, __PRETTY_FUNCTION__));
// Look for an inverted mask: (X & ~M) op (Y & M).
Value *M;
if (match(LHS, m_c_And(m_Not(m_Value(M)), m_Value())) &&
    match(RHS, m_c_And(m_Specific(M), m_Value())))
  return true;
if (match(RHS, m_c_And(m_Not(m_Value(M)), m_Value())) &&
    match(LHS, m_c_And(m_Specific(M), m_Value())))
  return true;
IntegerType *IT = cast<IntegerType>(LHS->getType()->getScalarType());
KnownBits LHSKnown(IT->getBitWidth());
KnownBits RHSKnown(IT->getBitWidth());
computeKnownBits(LHS, LHSKnown, DL, 0, AC, CxtI, DT, nullptr, UseInstrInfo);
computeKnownBits(RHS, RHSKnown, DL, 0, AC, CxtI, DT, nullptr, UseInstrInfo);
return (LHSKnown.Zero | RHSKnown.Zero).isAllOnesValue();
211}

213bool llvm::isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI) {
for (const User *U : CxtI->users()) {
  if (const ICmpInst *IC = dyn_cast<ICmpInst>(U))
    if (IC->isEquality())
      if (Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
        if (C->isNullValue())
          continue;
  return false;
}
return true;
223}

225static bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth,
                                 const Query &Q);

228bool llvm::isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL,
                                bool OrZero, unsigned Depth,
                                AssumptionCache *AC, const Instruction *CxtI,
                                const DominatorTree *DT, bool UseInstrInfo) {
return ::isKnownToBeAPowerOfTwo(
    V, OrZero, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo));
234}

236static bool isKnownNonZero(const Value *V, unsigned Depth, const Query &Q);

238bool llvm::isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth,
                        AssumptionCache *AC, const Instruction *CxtI,
                        const DominatorTree *DT, bool UseInstrInfo) {
return ::isKnownNonZero(V, Depth,
                        Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo));
243}

245bool llvm::isKnownNonNegative(const Value *V, const DataLayout &DL,
                            unsigned Depth, AssumptionCache *AC,
                            const Instruction *CxtI, const DominatorTree *DT,
                            bool UseInstrInfo) {
KnownBits Known =
    computeKnownBits(V, DL, Depth, AC, CxtI, DT, nullptr, UseInstrInfo);
return Known.isNonNegative();
252}

254bool llvm::isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth,
                         AssumptionCache *AC, const Instruction *CxtI,
                         const DominatorTree *DT, bool UseInstrInfo) {
if (auto *CI = dyn_cast<ConstantInt>(V))
  return CI->getValue().isStrictlyPositive();

// TODO: We'd doing two recursive queries here.  We should factor this such
// that only a single query is needed.
return isKnownNonNegative(V, DL, Depth, AC, CxtI, DT, UseInstrInfo) &&
       isKnownNonZero(V, DL, Depth, AC, CxtI, DT, UseInstrInfo);
264}

266bool llvm::isKnownNegative(const Value *V, const DataLayout &DL, unsigned Depth,
                         AssumptionCache *AC, const Instruction *CxtI,
                         const DominatorTree *DT, bool UseInstrInfo) {
KnownBits Known =
    computeKnownBits(V, DL, Depth, AC, CxtI, DT, nullptr, UseInstrInfo);
return Known.isNegative();
272}

274static bool isKnownNonEqual(const Value *V1, const Value *V2, const Query &Q);

276bool llvm::isKnownNonEqual(const Value *V1, const Value *V2,
                         const DataLayout &DL, AssumptionCache *AC,
                         const Instruction *CxtI, const DominatorTree *DT,
                         bool UseInstrInfo) {
return ::isKnownNonEqual(V1, V2,
                         Query(DL, AC, safeCxtI(V1, safeCxtI(V2, CxtI)), DT,
                               UseInstrInfo, /*ORE=*/nullptr));
283}

285static bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth,
                            const Query &Q);

288bool llvm::MaskedValueIsZero(const Value *V, const APInt &Mask,
                           const DataLayout &DL, unsigned Depth,
                           AssumptionCache *AC, const Instruction *CxtI,
                           const DominatorTree *DT, bool UseInstrInfo) {
return ::MaskedValueIsZero(
    V, Mask, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo));
294}

296static unsigned ComputeNumSignBits(const Value *V, unsigned Depth,
                                 const Query &Q);

299unsigned llvm::ComputeNumSignBits(const Value *V, const DataLayout &DL,
                                unsigned Depth, AssumptionCache *AC,
                                const Instruction *CxtI,
                                const DominatorTree *DT, bool UseInstrInfo) {
return ::ComputeNumSignBits(
    V, Depth, Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo));
305}

307static void computeKnownBitsAddSub(bool Add, const Value *Op0, const Value *Op1,
                                 bool NSW,
                                 KnownBits &KnownOut, KnownBits &Known2,
                                 unsigned Depth, const Query &Q) {
unsigned BitWidth = KnownOut.getBitWidth();

// If an initial sequence of bits in the result is not needed, the
// corresponding bits in the operands are not needed.
KnownBits LHSKnown(BitWidth);
computeKnownBits(Op0, LHSKnown, Depth + 1, Q);
computeKnownBits(Op1, Known2, Depth + 1, Q);

KnownOut = KnownBits::computeForAddSub(Add, NSW, LHSKnown, Known2);
320}

322static void computeKnownBitsMul(const Value *Op0, const Value *Op1, bool NSW,
                              KnownBits &Known, KnownBits &Known2,
                              unsigned Depth, const Query &Q) {
unsigned BitWidth = Known.getBitWidth();
computeKnownBits(Op1, Known, Depth + 1, Q);
computeKnownBits(Op0, Known2, Depth + 1, Q);

bool isKnownNegative = false;
bool isKnownNonNegative = false;
// If the multiplication is known not to overflow, compute the sign bit.
if (NSW) {
  if (Op0 == Op1) {
    // The product of a number with itself is non-negative.
    isKnownNonNegative = true;
  } else {
    bool isKnownNonNegativeOp1 = Known.isNonNegative();
    bool isKnownNonNegativeOp0 = Known2.isNonNegative();
    bool isKnownNegativeOp1 = Known.isNegative();
    bool isKnownNegativeOp0 = Known2.isNegative();
    // The product of two numbers with the same sign is non-negative.
    isKnownNonNegative = (isKnownNegativeOp1 && isKnownNegativeOp0) ||
      (isKnownNonNegativeOp1 && isKnownNonNegativeOp0);
    // The product of a negative number and a non-negative number is either
    // negative or zero.
    if (!isKnownNonNegative)
      isKnownNegative = (isKnownNegativeOp1 && isKnownNonNegativeOp0 &&
                         isKnownNonZero(Op0, Depth, Q)) ||
                        (isKnownNegativeOp0 && isKnownNonNegativeOp1 &&
                         isKnownNonZero(Op1, Depth, Q));
  }
}

assert(!Known.hasConflict() && !Known2.hasConflict())((!Known.hasConflict() && !Known2.hasConflict()) ? static_cast
<void> (0) : __assert_fail ("!Known.hasConflict() && !Known2.hasConflict()"
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 354, __PRETTY_FUNCTION__));
// Compute a conservative estimate for high known-0 bits.
unsigned LeadZ =  std::max(Known.countMinLeadingZeros() +
                           Known2.countMinLeadingZeros(),
                           BitWidth) - BitWidth;
LeadZ = std::min(LeadZ, BitWidth);

// The result of the bottom bits of an integer multiply can be
// inferred by looking at the bottom bits of both operands and
// multiplying them together.
// We can infer at least the minimum number of known trailing bits
// of both operands. Depending on number of trailing zeros, we can
// infer more bits, because (a*b) <=> ((a/m) * (b/n)) * (m*n) assuming
// a and b are divisible by m and n respectively.
// We then calculate how many of those bits are inferrable and set
// the output. For example, the i8 mul:
//  a = XXXX1100 (12)
//  b = XXXX1110 (14)
// We know the bottom 3 bits are zero since the first can be divided by
// 4 and the second by 2, thus having ((12/4) * (14/2)) * (2*4).
// Applying the multiplication to the trimmed arguments gets:
//    XX11 (3)
//    X111 (7)
// -------
//    XX11
//   XX11
//  XX11
// XX11
// -------
// XXXXX01
// Which allows us to infer the 2 LSBs. Since we're multiplying the result
// by 8, the bottom 3 bits will be 0, so we can infer a total of 5 bits.
// The proof for this can be described as:
// Pre: (C1 >= 0) && (C1 < (1 << C5)) && (C2 >= 0) && (C2 < (1 << C6)) &&
//      (C7 == (1 << (umin(countTrailingZeros(C1), C5) +
//                    umin(countTrailingZeros(C2), C6) +
//                    umin(C5 - umin(countTrailingZeros(C1), C5),
//                         C6 - umin(countTrailingZeros(C2), C6)))) - 1)
// %aa = shl i8 %a, C5
// %bb = shl i8 %b, C6
// %aaa = or i8 %aa, C1
// %bbb = or i8 %bb, C2
// %mul = mul i8 %aaa, %bbb
// %mask = and i8 %mul, C7
//   =>
// %mask = i8 ((C1*C2)&C7)
// Where C5, C6 describe the known bits of %a, %b
// C1, C2 describe the known bottom bits of %a, %b.
// C7 describes the mask of the known bits of the result.
APInt Bottom0 = Known.One;
APInt Bottom1 = Known2.One;

// How many times we'd be able to divide each argument by 2 (shr by 1).
// This gives us the number of trailing zeros on the multiplication result.
unsigned TrailBitsKnown0 = (Known.Zero | Known.One).countTrailingOnes();
unsigned TrailBitsKnown1 = (Known2.Zero | Known2.One).countTrailingOnes();
unsigned TrailZero0 = Known.countMinTrailingZeros();
unsigned TrailZero1 = Known2.countMinTrailingZeros();
unsigned TrailZ = TrailZero0 + TrailZero1;

// Figure out the fewest known-bits operand.
unsigned SmallestOperand = std::min(TrailBitsKnown0 - TrailZero0,
                                    TrailBitsKnown1 - TrailZero1);
unsigned ResultBitsKnown = std::min(SmallestOperand + TrailZ, BitWidth);

APInt BottomKnown = Bottom0.getLoBits(TrailBitsKnown0) *
                    Bottom1.getLoBits(TrailBitsKnown1);

Known.resetAll();
Known.Zero.setHighBits(LeadZ);
Known.Zero |= (~BottomKnown).getLoBits(ResultBitsKnown);
Known.One |= BottomKnown.getLoBits(ResultBitsKnown);

// Only make use of no-wrap flags if we failed to compute the sign bit
// directly.  This matters if the multiplication always overflows, in
// which case we prefer to follow the result of the direct computation,
// though as the program is invoking undefined behaviour we can choose
// whatever we like here.
if (isKnownNonNegative && !Known.isNegative())
  Known.makeNonNegative();
else if (isKnownNegative && !Known.isNonNegative())
  Known.makeNegative();
436}

438void llvm::computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
                                           KnownBits &Known) {
unsigned BitWidth = Known.getBitWidth();
unsigned NumRanges = Ranges.getNumOperands() / 2;
assert(NumRanges >= 1)((NumRanges >= 1) ? static_cast<void> (0) : __assert_fail
 ("NumRanges >= 1", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 442, __PRETTY_FUNCTION__));

Known.Zero.setAllBits();
Known.One.setAllBits();

for (unsigned i = 0; i < NumRanges; ++i) {
  ConstantInt *Lower =
      mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 0));
  ConstantInt *Upper =
      mdconst::extract<ConstantInt>(Ranges.getOperand(2 * i + 1));
  ConstantRange Range(Lower->getValue(), Upper->getValue());

  // The first CommonPrefixBits of all values in Range are equal.
  unsigned CommonPrefixBits =
      (Range.getUnsignedMax() ^ Range.getUnsignedMin()).countLeadingZeros();

  APInt Mask = APInt::getHighBitsSet(BitWidth, CommonPrefixBits);
  Known.One &= Range.getUnsignedMax() & Mask;
  Known.Zero &= ~Range.getUnsignedMax() & Mask;
}
462}

464static bool isEphemeralValueOf(const Instruction *I, const Value *E) {
SmallVector<const Value *, 16> WorkSet(1, I);
SmallPtrSet<const Value *, 32> Visited;
SmallPtrSet<const Value *, 16> EphValues;

// The instruction defining an assumption's condition itself is always
// considered ephemeral to that assumption (even if it has other
// non-ephemeral users). See r246696's test case for an example.
if (is_contained(I->operands(), E))
  return true;

while (!WorkSet.empty()) {
  const Value *V = WorkSet.pop_back_val();
  if (!Visited.insert(V).second)
    continue;

  // If all uses of this value are ephemeral, then so is this value.
  if (llvm::all_of(V->users(), [&](const User *U) {
                                 return EphValues.count(U);
                               })) {
    if (V == E)
      return true;

    if (V == I || isSafeToSpeculativelyExecute(V)) {
     EphValues.insert(V);
     if (const User *U = dyn_cast<User>(V))
       for (User::const_op_iterator J = U->op_begin(), JE = U->op_end();
            J != JE; ++J)
         WorkSet.push_back(*J);
    }
  }
}

return false;
498}

500// Is this an intrinsic that cannot be speculated but also cannot trap?
501bool llvm::isAssumeLikeIntrinsic(const Instruction *I) {
if (const CallInst *CI = dyn_cast<CallInst>(I))
  if (Function *F = CI->getCalledFunction())
    switch (F->getIntrinsicID()) {
    default: break;
    // FIXME: This list is repeated from NoTTI::getIntrinsicCost.
    case Intrinsic::assume:
    case Intrinsic::sideeffect:
    case Intrinsic::dbg_declare:
    case Intrinsic::dbg_value:
    case Intrinsic::dbg_label:
    case Intrinsic::invariant_start:
    case Intrinsic::invariant_end:
    case Intrinsic::lifetime_start:
    case Intrinsic::lifetime_end:
    case Intrinsic::objectsize:
    case Intrinsic::ptr_annotation:
    case Intrinsic::var_annotation:
      return true;
    }

return false;
523}

525bool llvm::isValidAssumeForContext(const Instruction *Inv,
                                 const Instruction *CxtI,
                                 const DominatorTree *DT) {
// There are two restrictions on the use of an assume:
//  1. The assume must dominate the context (or the control flow must
//     reach the assume whenever it reaches the context).
//  2. The context must not be in the assume's set of ephemeral values
//     (otherwise we will use the assume to prove that the condition
//     feeding the assume is trivially true, thus causing the removal of
//     the assume).

if (DT) {
  if (DT->dominates(Inv, CxtI))
    return true;
} else if (Inv->getParent() == CxtI->getParent()->getSinglePredecessor()) {
  // We don't have a DT, but this trivially dominates.
  return true;
}

// With or without a DT, the only remaining case we will check is if the
// instructions are in the same BB.  Give up if that is not the case.
if (Inv->getParent() != CxtI->getParent())
  return false;

// If we have a dom tree, then we now know that the assume doesn't dominate
// the other instruction.  If we don't have a dom tree then we can check if
// the assume is first in the BB.
if (!DT) {
  // Search forward from the assume until we reach the context (or the end
  // of the block); the common case is that the assume will come first.
  for (auto I = std::next(BasicBlock::const_iterator(Inv)),
       IE = Inv->getParent()->end(); I != IE; ++I)
    if (&*I == CxtI)
      return true;
}

// Don't let an assume affect itself - this would cause the problems
// `isEphemeralValueOf` is trying to prevent, and it would also make
// the loop below go out of bounds.
if (Inv == CxtI)
  return false;

// The context comes first, but they're both in the same block. Make sure
// there is nothing in between that might interrupt the control flow.
for (BasicBlock::const_iterator I =
       std::next(BasicBlock::const_iterator(CxtI)), IE(Inv);
     I != IE; ++I)
  if (!isGuaranteedToTransferExecutionToSuccessor(&*I))
    return false;

return !isEphemeralValueOf(Inv, CxtI);
576}

578static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known,
                                     unsigned Depth, const Query &Q) {
// Use of assumptions is context-sensitive. If we don't have a context, we
// cannot use them!
if (!Q.AC || !Q.CxtI)
  return;

unsigned BitWidth = Known.getBitWidth();

// Note that the patterns below need to be kept in sync with the code
// in AssumptionCache::updateAffectedValues.

for (auto &AssumeVH : Q.AC->assumptionsFor(V)) {
  if (!AssumeVH)
    continue;
  CallInst *I = cast<CallInst>(AssumeVH);
  assert(I->getParent()->getParent() == Q.CxtI->getParent()->getParent() &&((I->getParent()->getParent() == Q.CxtI->getParent()
->getParent() && "Got assumption for the wrong function!"
) ? static_cast<void> (0) : __assert_fail ("I->getParent()->getParent() == Q.CxtI->getParent()->getParent() && \"Got assumption for the wrong function!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 595, __PRETTY_FUNCTION__))
         "Got assumption for the wrong function!")((I->getParent()->getParent() == Q.CxtI->getParent()
->getParent() && "Got assumption for the wrong function!"
) ? static_cast<void> (0) : __assert_fail ("I->getParent()->getParent() == Q.CxtI->getParent()->getParent() && \"Got assumption for the wrong function!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 595, __PRETTY_FUNCTION__));
  if (Q.isExcluded(I))
    continue;

  // Warning: This loop can end up being somewhat performance sensitive.
  // We're running this loop for once for each value queried resulting in a
  // runtime of ~O(#assumes * #values).

  assert(I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume &&((I->getCalledFunction()->getIntrinsicID() == Intrinsic
::assume && "must be an assume intrinsic") ? static_cast
<void> (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 604, __PRETTY_FUNCTION__))
         "must be an assume intrinsic")((I->getCalledFunction()->getIntrinsicID() == Intrinsic
::assume && "must be an assume intrinsic") ? static_cast
<void> (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 604, __PRETTY_FUNCTION__));

  Value *Arg = I->getArgOperand(0);

  if (Arg == V && isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
    assert(BitWidth == 1 && "assume operand is not i1?")((BitWidth == 1 && "assume operand is not i1?") ? static_cast
<void> (0) : __assert_fail ("BitWidth == 1 && \"assume operand is not i1?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 609, __PRETTY_FUNCTION__));
    Known.setAllOnes();
    return;
  }
  if (match(Arg, m_Not(m_Specific(V))) &&
      isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
    assert(BitWidth == 1 && "assume operand is not i1?")((BitWidth == 1 && "assume operand is not i1?") ? static_cast
<void> (0) : __assert_fail ("BitWidth == 1 && \"assume operand is not i1?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 615, __PRETTY_FUNCTION__));
    Known.setAllZero();
    return;
  }

  // The remaining tests are all recursive, so bail out if we hit the limit.
  if (Depth == MaxDepth)
    continue;

  ICmpInst *Cmp = dyn_cast<ICmpInst>(Arg);
  if (!Cmp)
    continue;

  Value *A, *B;
  auto m_V = m_CombineOr(m_Specific(V), m_PtrToInt(m_Specific(V)));

  CmpInst::Predicate Pred;
  uint64_t C;
  switch (Cmp->getPredicate()) {
  default:
    break;
  case ICmpInst::ICMP_EQ:
    // assume(v = a)
    if (match(Cmp, m_c_ICmp(Pred, m_V, m_Value(A))) &&
        isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
      Known.Zero |= RHSKnown.Zero;
      Known.One  |= RHSKnown.One;
    // assume(v & b = a)
    } else if (match(Cmp,
                     m_c_ICmp(Pred, m_c_And(m_V, m_Value(B)), m_Value(A))) &&
               isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
      KnownBits MaskKnown(BitWidth);
      computeKnownBits(B, MaskKnown, Depth+1, Query(Q, I));

      // For those bits in the mask that are known to be one, we can propagate
      // known bits from the RHS to V.
      Known.Zero |= RHSKnown.Zero & MaskKnown.One;
      Known.One  |= RHSKnown.One  & MaskKnown.One;
    // assume(~(v & b) = a)
    } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_And(m_V, m_Value(B))),
                                   m_Value(A))) &&
               isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
      KnownBits MaskKnown(BitWidth);
      computeKnownBits(B, MaskKnown, Depth+1, Query(Q, I));

      // For those bits in the mask that are known to be one, we can propagate
      // inverted known bits from the RHS to V.
      Known.Zero |= RHSKnown.One  & MaskKnown.One;
      Known.One  |= RHSKnown.Zero & MaskKnown.One;
    // assume(v | b = a)
    } else if (match(Cmp,
                     m_c_ICmp(Pred, m_c_Or(m_V, m_Value(B)), m_Value(A))) &&
               isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
      KnownBits BKnown(BitWidth);
      computeKnownBits(B, BKnown, Depth+1, Query(Q, I));

      // For those bits in B that are known to be zero, we can propagate known
      // bits from the RHS to V.
      Known.Zero |= RHSKnown.Zero & BKnown.Zero;
      Known.One  |= RHSKnown.One  & BKnown.Zero;
    // assume(~(v | b) = a)
    } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Or(m_V, m_Value(B))),
                                   m_Value(A))) &&
               isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
      KnownBits BKnown(BitWidth);
      computeKnownBits(B, BKnown, Depth+1, Query(Q, I));

      // For those bits in B that are known to be zero, we can propagate
      // inverted known bits from the RHS to V.
      Known.Zero |= RHSKnown.One  & BKnown.Zero;
      Known.One  |= RHSKnown.Zero & BKnown.Zero;
    // assume(v ^ b = a)
    } else if (match(Cmp,
                     m_c_ICmp(Pred, m_c_Xor(m_V, m_Value(B)), m_Value(A))) &&
               isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
      KnownBits BKnown(BitWidth);
      computeKnownBits(B, BKnown, Depth+1, Query(Q, I));

      // For those bits in B that are known to be zero, we can propagate known
      // bits from the RHS to V. For those bits in B that are known to be one,
      // we can propagate inverted known bits from the RHS to V.
      Known.Zero |= RHSKnown.Zero & BKnown.Zero;
      Known.One  |= RHSKnown.One  & BKnown.Zero;
      Known.Zero |= RHSKnown.One  & BKnown.One;
      Known.One  |= RHSKnown.Zero & BKnown.One;
    // assume(~(v ^ b) = a)
    } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Xor(m_V, m_Value(B))),
                                   m_Value(A))) &&
               isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
      KnownBits BKnown(BitWidth);
      computeKnownBits(B, BKnown, Depth+1, Query(Q, I));

      // For those bits in B that are known to be zero, we can propagate
      // inverted known bits from the RHS to V. For those bits in B that are
      // known to be one, we can propagate known bits from the RHS to V.
      Known.Zero |= RHSKnown.One  & BKnown.Zero;
      Known.One  |= RHSKnown.Zero & BKnown.Zero;
      Known.Zero |= RHSKnown.Zero & BKnown.One;
      Known.One  |= RHSKnown.One  & BKnown.One;
    // assume(v << c = a)
    } else if (match(Cmp, m_c_ICmp(Pred, m_Shl(m_V, m_ConstantInt(C)),
                                   m_Value(A))) &&
               isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
      // For those bits in RHS that are known, we can propagate them to known
      // bits in V shifted to the right by C.
      RHSKnown.Zero.lshrInPlace(C);
      Known.Zero |= RHSKnown.Zero;
      RHSKnown.One.lshrInPlace(C);
      Known.One  |= RHSKnown.One;
    // assume(~(v << c) = a)
    } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shl(m_V, m_ConstantInt(C))),
                                   m_Value(A))) &&
               isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
      // For those bits in RHS that are known, we can propagate them inverted
      // to known bits in V shifted to the right by C.
      RHSKnown.One.lshrInPlace(C);
      Known.Zero |= RHSKnown.One;
      RHSKnown.Zero.lshrInPlace(C);
      Known.One  |= RHSKnown.Zero;
    // assume(v >> c = a)
    } else if (match(Cmp, m_c_ICmp(Pred, m_Shr(m_V, m_ConstantInt(C)),
                                   m_Value(A))) &&
               isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
      // For those bits in RHS that are known, we can propagate them to known
      // bits in V shifted to the right by C.
      Known.Zero |= RHSKnown.Zero << C;
      Known.One  |= RHSKnown.One  << C;
    // assume(~(v >> c) = a)
    } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shr(m_V, m_ConstantInt(C))),
                                   m_Value(A))) &&
               isValidAssumeForContext(I, Q.CxtI, Q.DT) && C < BitWidth) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));
      // For those bits in RHS that are known, we can propagate them inverted
      // to known bits in V shifted to the right by C.
      Known.Zero |= RHSKnown.One  << C;
      Known.One  |= RHSKnown.Zero << C;
    }
    break;
  case ICmpInst::ICMP_SGE:
    // assume(v >=_s c) where c is non-negative
    if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) &&
        isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth + 1, Query(Q, I));

      if (RHSKnown.isNonNegative()) {
        // We know that the sign bit is zero.
        Known.makeNonNegative();
      }
    }
    break;
  case ICmpInst::ICMP_SGT:
    // assume(v >_s c) where c is at least -1.
    if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) &&
        isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth + 1, Query(Q, I));

      if (RHSKnown.isAllOnes() || RHSKnown.isNonNegative()) {
        // We know that the sign bit is zero.
        Known.makeNonNegative();
      }
    }
    break;
  case ICmpInst::ICMP_SLE:
    // assume(v <=_s c) where c is negative
    if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) &&
        isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth + 1, Query(Q, I));

      if (RHSKnown.isNegative()) {
        // We know that the sign bit is one.
        Known.makeNegative();
      }
    }
    break;
  case ICmpInst::ICMP_SLT:
    // assume(v <_s c) where c is non-positive
    if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) &&
        isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));

      if (RHSKnown.isZero() || RHSKnown.isNegative()) {
        // We know that the sign bit is one.
        Known.makeNegative();
      }
    }
    break;
  case ICmpInst::ICMP_ULE:
    // assume(v <=_u c)
    if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) &&
        isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));

      // Whatever high bits in c are zero are known to be zero.
      Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros());
    }
    break;
  case ICmpInst::ICMP_ULT:
    // assume(v <_u c)
    if (match(Cmp, m_ICmp(Pred, m_V, m_Value(A))) &&
        isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
      KnownBits RHSKnown(BitWidth);
      computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I));

      // If the RHS is known zero, then this assumption must be wrong (nothing
      // is unsigned less than zero). Signal a conflict and get out of here.
      if (RHSKnown.isZero()) {
        Known.Zero.setAllBits();
        Known.One.setAllBits();
        break;
      }

      // Whatever high bits in c are zero are known to be zero (if c is a power
      // of 2, then one more).
      if (isKnownToBeAPowerOfTwo(A, false, Depth + 1, Query(Q, I)))
        Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros() + 1);
      else
        Known.Zero.setHighBits(RHSKnown.countMinLeadingZeros());
    }
    break;
  }
}

// If assumptions conflict with each other or previous known bits, then we
// have a logical fallacy. It's possible that the assumption is not reachable,
// so this isn't a real bug. On the other hand, the program may have undefined
// behavior, or we might have a bug in the compiler. We can't assert/crash, so
// clear out the known bits, try to warn the user, and hope for the best.
if (Known.Zero.intersects(Known.One)) {
  Known.resetAll();

  if (Q.ORE)
    Q.ORE->emit([&]() {
      auto *CxtI = const_cast<Instruction *>(Q.CxtI);
      return OptimizationRemarkAnalysis("value-tracking", "BadAssumption",
                                        CxtI)
             << "Detected conflicting code assumptions. Program may "
                "have undefined behavior, or compiler may have "
                "internal error.";
    });
}
881}

883/// Compute known bits from a shift operator, including those with a
884/// non-constant shift amount. Known is the output of this function. Known2 is a
885/// pre-allocated temporary with the same bit width as Known. KZF and KOF are
886/// operator-specific functions that, given the known-zero or known-one bits
887/// respectively, and a shift amount, compute the implied known-zero or
888/// known-one bits of the shift operator's result respectively for that shift
889/// amount. The results from calling KZF and KOF are conservatively combined for
890/// all permitted shift amounts.
891static void computeKnownBitsFromShiftOperator(
  const Operator *I, KnownBits &Known, KnownBits &Known2,
  unsigned Depth, const Query &Q,
  function_ref<APInt(const APInt &, unsigned)> KZF,
  function_ref<APInt(const APInt &, unsigned)> KOF) {
unsigned BitWidth = Known.getBitWidth();

if (auto *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
  unsigned ShiftAmt = SA->getLimitedValue(BitWidth-1);

  computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
  Known.Zero = KZF(Known.Zero, ShiftAmt);
  Known.One  = KOF(Known.One, ShiftAmt);
  // If the known bits conflict, this must be an overflowing left shift, so
  // the shift result is poison. We can return anything we want. Choose 0 for
  // the best folding opportunity.
  if (Known.hasConflict())
    Known.setAllZero();

  return;
}

computeKnownBits(I->getOperand(1), Known, Depth + 1, Q);

// If the shift amount could be greater than or equal to the bit-width of the
// LHS, the value could be poison, but bail out because the check below is
// expensive. TODO: Should we just carry on?
if ((~Known.Zero).uge(BitWidth)) {
  Known.resetAll();
  return;
}

// Note: We cannot use Known.Zero.getLimitedValue() here, because if
// BitWidth > 64 and any upper bits are known, we'll end up returning the
// limit value (which implies all bits are known).
uint64_t ShiftAmtKZ = Known.Zero.zextOrTrunc(64).getZExtValue();
uint64_t ShiftAmtKO = Known.One.zextOrTrunc(64).getZExtValue();

// It would be more-clearly correct to use the two temporaries for this
// calculation. Reusing the APInts here to prevent unnecessary allocations.
Known.resetAll();

// If we know the shifter operand is nonzero, we can sometimes infer more
// known bits. However this is expensive to compute, so be lazy about it and
// only compute it when absolutely necessary.
Optional<bool> ShifterOperandIsNonZero;

// Early exit if we can't constrain any well-defined shift amount.
if (!(ShiftAmtKZ & (PowerOf2Ceil(BitWidth) - 1)) &&
    !(ShiftAmtKO & (PowerOf2Ceil(BitWidth) - 1))) {
  ShifterOperandIsNonZero = isKnownNonZero(I->getOperand(1), Depth + 1, Q);
  if (!*ShifterOperandIsNonZero)
    return;
}

computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);

Known.Zero.setAllBits();
Known.One.setAllBits();
for (unsigned ShiftAmt = 0; ShiftAmt < BitWidth; ++ShiftAmt) {
  // Combine the shifted known input bits only for those shift amounts
  // compatible with its known constraints.
  if ((ShiftAmt & ~ShiftAmtKZ) != ShiftAmt)
    continue;
  if ((ShiftAmt | ShiftAmtKO) != ShiftAmt)
    continue;
  // If we know the shifter is nonzero, we may be able to infer more known
  // bits. This check is sunk down as far as possible to avoid the expensive
  // call to isKnownNonZero if the cheaper checks above fail.
  if (ShiftAmt == 0) {
    if (!ShifterOperandIsNonZero.hasValue())
      ShifterOperandIsNonZero =
          isKnownNonZero(I->getOperand(1), Depth + 1, Q);
    if (*ShifterOperandIsNonZero)
      continue;
  }

  Known.Zero &= KZF(Known2.Zero, ShiftAmt);
  Known.One  &= KOF(Known2.One, ShiftAmt);
}

// If the known bits conflict, the result is poison. Return a 0 and hope the
// caller can further optimize that.
if (Known.hasConflict())
  Known.setAllZero();
976}

978static void computeKnownBitsFromOperator(const Operator *I, KnownBits &Known,
                                       unsigned Depth, const Query &Q) {
unsigned BitWidth = Known.getBitWidth();

KnownBits Known2(Known);
switch (I->getOpcode()) {
1
Calling 'Operator::getOpcode'→
5
←
Returning from 'Operator::getOpcode'→
6
←
Control jumps to 'case Select:'  at line 1057→
default: break;
case Instruction::Load:
  if (MDNode *MD =
          Q.IIQ.getMetadata(cast<LoadInst>(I), LLVMContext::MD_range))
    computeKnownBitsFromRangeMetadata(*MD, Known);
  break;
case Instruction::And: {
  // If either the LHS or the RHS are Zero, the result is zero.
  computeKnownBits(I->getOperand(1), Known, Depth + 1, Q);
  computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);

  // Output known-1 bits are only known if set in both the LHS & RHS.
  Known.One &= Known2.One;
  // Output known-0 are known to be clear if zero in either the LHS | RHS.
  Known.Zero |= Known2.Zero;

  // and(x, add (x, -1)) is a common idiom that always clears the low bit;
  // here we handle the more general case of adding any odd number by
  // matching the form add(x, add(x, y)) where y is odd.
  // TODO: This could be generalized to clearing any bit set in y where the
  // following bit is known to be unset in y.
  Value *X = nullptr, *Y = nullptr;
  if (!Known.Zero[0] && !Known.One[0] &&
      match(I, m_c_BinOp(m_Value(X), m_Add(m_Deferred(X), m_Value(Y))))) {
    Known2.resetAll();
    computeKnownBits(Y, Known2, Depth + 1, Q);
    if (Known2.countMinTrailingOnes() > 0)
      Known.Zero.setBit(0);
  }
  break;
}
case Instruction::Or:
  computeKnownBits(I->getOperand(1), Known, Depth + 1, Q);
  computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);

  // Output known-0 bits are only known if clear in both the LHS & RHS.
  Known.Zero &= Known2.Zero;
  // Output known-1 are known to be set if set in either the LHS | RHS.
  Known.One |= Known2.One;
  break;
case Instruction::Xor: {
  computeKnownBits(I->getOperand(1), Known, Depth + 1, Q);
  computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);

  // Output known-0 bits are known if clear or set in both the LHS & RHS.
  APInt KnownZeroOut = (Known.Zero & Known2.Zero) | (Known.One & Known2.One);
  // Output known-1 are known to be set if set in only one of the LHS, RHS.
  Known.One = (Known.Zero & Known2.One) | (Known.One & Known2.Zero);
  Known.Zero = std::move(KnownZeroOut);
  break;
}
case Instruction::Mul: {
  bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I));
  computeKnownBitsMul(I->getOperand(0), I->getOperand(1), NSW, Known,
                      Known2, Depth, Q);
  break;
}
case Instruction::UDiv: {
  // For the purposes of computing leading zeros we can conservatively
  // treat a udiv as a logical right shift by the power of 2 known to
  // be less than the denominator.
  computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
  unsigned LeadZ = Known2.countMinLeadingZeros();

  Known2.resetAll();
  computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
  unsigned RHSMaxLeadingZeros = Known2.countMaxLeadingZeros();
  if (RHSMaxLeadingZeros != BitWidth)
    LeadZ = std::min(BitWidth, LeadZ + BitWidth - RHSMaxLeadingZeros - 1);

  Known.Zero.setHighBits(LeadZ);
  break;
}
case Instruction::Select: {
  const Value *LHS, *RHS;
7
←
'LHS' declared without an initial value→
  SelectPatternFlavor SPF = matchSelectPattern(I, LHS, RHS).Flavor;
8
←
Passing value via 2nd parameter 'LHS'→
9
←
Calling 'matchSelectPattern'→
  if (SelectPatternResult::isMinOrMax(SPF)) {
    computeKnownBits(RHS, Known, Depth + 1, Q);
    computeKnownBits(LHS, Known2, Depth + 1, Q);
  } else {
    computeKnownBits(I->getOperand(2), Known, Depth + 1, Q);
    computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
  }

  unsigned MaxHighOnes = 0;
  unsigned MaxHighZeros = 0;
  if (SPF == SPF_SMAX) {
    // If both sides are negative, the result is negative.
    if (Known.isNegative() && Known2.isNegative())
      // We can derive a lower bound on the result by taking the max of the
      // leading one bits.
      MaxHighOnes =
          std::max(Known.countMinLeadingOnes(), Known2.countMinLeadingOnes());
    // If either side is non-negative, the result is non-negative.
    else if (Known.isNonNegative() || Known2.isNonNegative())
      MaxHighZeros = 1;
  } else if (SPF == SPF_SMIN) {
    // If both sides are non-negative, the result is non-negative.
    if (Known.isNonNegative() && Known2.isNonNegative())
      // We can derive an upper bound on the result by taking the max of the
      // leading zero bits.
      MaxHighZeros = std::max(Known.countMinLeadingZeros(),
                              Known2.countMinLeadingZeros());
    // If either side is negative, the result is negative.
    else if (Known.isNegative() || Known2.isNegative())
      MaxHighOnes = 1;
  } else if (SPF == SPF_UMAX) {
    // We can derive a lower bound on the result by taking the max of the
    // leading one bits.
    MaxHighOnes =
        std::max(Known.countMinLeadingOnes(), Known2.countMinLeadingOnes());
  } else if (SPF == SPF_UMIN) {
    // We can derive an upper bound on the result by taking the max of the
    // leading zero bits.
    MaxHighZeros =
        std::max(Known.countMinLeadingZeros(), Known2.countMinLeadingZeros());
  } else if (SPF == SPF_ABS) {
    // RHS from matchSelectPattern returns the negation part of abs pattern.
    // If the negate has an NSW flag we can assume the sign bit of the result
    // will be 0 because that makes abs(INT_MIN) undefined.
    if (match(RHS, m_Neg(m_Specific(LHS))) &&
        Q.IIQ.hasNoSignedWrap(cast<Instruction>(RHS)))
      MaxHighZeros = 1;
  }

  // Only known if known in both the LHS and RHS.
  Known.One &= Known2.One;
  Known.Zero &= Known2.Zero;
  if (MaxHighOnes > 0)
    Known.One.setHighBits(MaxHighOnes);
  if (MaxHighZeros > 0)
    Known.Zero.setHighBits(MaxHighZeros);
  break;
}
case Instruction::FPTrunc:
case Instruction::FPExt:
case Instruction::FPToUI:
case Instruction::FPToSI:
case Instruction::SIToFP:
case Instruction::UIToFP:
  break; // Can't work with floating point.
case Instruction::PtrToInt:
case Instruction::IntToPtr:
  // Fall through and handle them the same as zext/trunc.
  LLVM_FALLTHROUGH[[gnu::fallthrough]];
case Instruction::ZExt:
case Instruction::Trunc: {
  Type *SrcTy = I->getOperand(0)->getType();

  unsigned SrcBitWidth;
  // Note that we handle pointer operands here because of inttoptr/ptrtoint
  // which fall through here.
  Type *ScalarTy = SrcTy->getScalarType();
  SrcBitWidth = ScalarTy->isPointerTy() ?
    Q.DL.getIndexTypeSizeInBits(ScalarTy) :
    Q.DL.getTypeSizeInBits(ScalarTy);

  assert(SrcBitWidth && "SrcBitWidth can't be zero")((SrcBitWidth && "SrcBitWidth can't be zero") ? static_cast
<void> (0) : __assert_fail ("SrcBitWidth && \"SrcBitWidth can't be zero\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1141, __PRETTY_FUNCTION__));
  Known = Known.zextOrTrunc(SrcBitWidth, false);
  computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
  Known = Known.zextOrTrunc(BitWidth, true /* ExtendedBitsAreKnownZero */);
  break;
}
case Instruction::BitCast: {
  Type *SrcTy = I->getOperand(0)->getType();
  if (SrcTy->isIntOrPtrTy() &&
      // TODO: For now, not handling conversions like:
      // (bitcast i64 %x to <2 x i32>)
      !I->getType()->isVectorTy()) {
    computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
    break;
  }
  break;
}
case Instruction::SExt: {
  // Compute the bits in the result that are not present in the input.
  unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits();

  Known = Known.trunc(SrcBitWidth);
  computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
  // If the sign bit of the input is known set or clear, then we know the
  // top bits of the result.
  Known = Known.sext(BitWidth);
  break;
}
case Instruction::Shl: {
  // (shl X, C1) & C2 == 0   iff   (X & C2 >>u C1) == 0
  bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I));
  auto KZF = [NSW](const APInt &KnownZero, unsigned ShiftAmt) {
    APInt KZResult = KnownZero << ShiftAmt;
    KZResult.setLowBits(ShiftAmt); // Low bits known 0.
    // If this shift has "nsw" keyword, then the result is either a poison
    // value or has the same sign bit as the first operand.
    if (NSW && KnownZero.isSignBitSet())
      KZResult.setSignBit();
    return KZResult;
  };

  auto KOF = [NSW](const APInt &KnownOne, unsigned ShiftAmt) {
    APInt KOResult = KnownOne << ShiftAmt;
    if (NSW && KnownOne.isSignBitSet())
      KOResult.setSignBit();
    return KOResult;
  };

  computeKnownBitsFromShiftOperator(I, Known, Known2, Depth, Q, KZF, KOF);
  break;
}
case Instruction::LShr: {
  // (lshr X, C1) & C2 == 0   iff  (-1 >> C1) & C2 == 0
  auto KZF = [](const APInt &KnownZero, unsigned ShiftAmt) {
    APInt KZResult = KnownZero.lshr(ShiftAmt);
    // High bits known zero.
    KZResult.setHighBits(ShiftAmt);
    return KZResult;
  };

  auto KOF = [](const APInt &KnownOne, unsigned ShiftAmt) {
    return KnownOne.lshr(ShiftAmt);
  };

  computeKnownBitsFromShiftOperator(I, Known, Known2, Depth, Q, KZF, KOF);
  break;
}
case Instruction::AShr: {
  // (ashr X, C1) & C2 == 0   iff  (-1 >> C1) & C2 == 0
  auto KZF = [](const APInt &KnownZero, unsigned ShiftAmt) {
    return KnownZero.ashr(ShiftAmt);
  };

  auto KOF = [](const APInt &KnownOne, unsigned ShiftAmt) {
    return KnownOne.ashr(ShiftAmt);
  };

  computeKnownBitsFromShiftOperator(I, Known, Known2, Depth, Q, KZF, KOF);
  break;
}
case Instruction::Sub: {
  bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I));
  computeKnownBitsAddSub(false, I->getOperand(0), I->getOperand(1), NSW,
                         Known, Known2, Depth, Q);
  break;
}
case Instruction::Add: {
  bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I));
  computeKnownBitsAddSub(true, I->getOperand(0), I->getOperand(1), NSW,
                         Known, Known2, Depth, Q);
  break;
}
case Instruction::SRem:
  if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
    APInt RA = Rem->getValue().abs();
    if (RA.isPowerOf2()) {
      APInt LowBits = RA - 1;
      computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);

      // The low bits of the first operand are unchanged by the srem.
      Known.Zero = Known2.Zero & LowBits;
      Known.One = Known2.One & LowBits;

      // If the first operand is non-negative or has all low bits zero, then
      // the upper bits are all zero.
      if (Known2.isNonNegative() || LowBits.isSubsetOf(Known2.Zero))
        Known.Zero |= ~LowBits;

      // If the first operand is negative and not all low bits are zero, then
      // the upper bits are all one.
      if (Known2.isNegative() && LowBits.intersects(Known2.One))
        Known.One |= ~LowBits;

      assert((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?")(((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?"
) ? static_cast<void> (0) : __assert_fail ("(Known.Zero & Known.One) == 0 && \"Bits known to be one AND zero?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1254, __PRETTY_FUNCTION__));
      break;
    }
  }

  // The sign bit is the LHS's sign bit, except when the result of the
  // remainder is zero.
  computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
  // If it's known zero, our sign bit is also zero.
  if (Known2.isNonNegative())
    Known.makeNonNegative();

  break;
case Instruction::URem: {
  if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
    const APInt &RA = Rem->getValue();
    if (RA.isPowerOf2()) {
      APInt LowBits = (RA - 1);
      computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
      Known.Zero |= ~LowBits;
      Known.One &= LowBits;
      break;
    }
  }

  // Since the result is less than or equal to either operand, any leading
  // zero bits in either operand must also exist in the result.
  computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
  computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);

  unsigned Leaders =
      std::max(Known.countMinLeadingZeros(), Known2.countMinLeadingZeros());
  Known.resetAll();
  Known.Zero.setHighBits(Leaders);
  break;
}

case Instruction::Alloca: {
  const AllocaInst *AI = cast<AllocaInst>(I);
  unsigned Align = AI->getAlignment();
  if (Align == 0)
    Align = Q.DL.getABITypeAlignment(AI->getAllocatedType());

  if (Align > 0)
    Known.Zero.setLowBits(countTrailingZeros(Align));
  break;
}
case Instruction::GetElementPtr: {
  // Analyze all of the subscripts of this getelementptr instruction
  // to determine if we can prove known low zero bits.
  KnownBits LocalKnown(BitWidth);
  computeKnownBits(I->getOperand(0), LocalKnown, Depth + 1, Q);
  unsigned TrailZ = LocalKnown.countMinTrailingZeros();

  gep_type_iterator GTI = gep_type_begin(I);
  for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i, ++GTI) {
    Value *Index = I->getOperand(i);
    if (StructType *STy = GTI.getStructTypeOrNull()) {
      // Handle struct member offset arithmetic.

      // Handle case when index is vector zeroinitializer
      Constant *CIndex = cast<Constant>(Index);
      if (CIndex->isZeroValue())
        continue;

      if (CIndex->getType()->isVectorTy())
        Index = CIndex->getSplatValue();

      unsigned Idx = cast<ConstantInt>(Index)->getZExtValue();
      const StructLayout *SL = Q.DL.getStructLayout(STy);
      uint64_t Offset = SL->getElementOffset(Idx);
      TrailZ = std::min<unsigned>(TrailZ,
                                  countTrailingZeros(Offset));
    } else {
      // Handle array index arithmetic.
      Type *IndexedTy = GTI.getIndexedType();
      if (!IndexedTy->isSized()) {
        TrailZ = 0;
        break;
      }
      unsigned GEPOpiBits = Index->getType()->getScalarSizeInBits();
      uint64_t TypeSize = Q.DL.getTypeAllocSize(IndexedTy);
      LocalKnown.Zero = LocalKnown.One = APInt(GEPOpiBits, 0);
      computeKnownBits(Index, LocalKnown, Depth + 1, Q);
      TrailZ = std::min(TrailZ,
                        unsigned(countTrailingZeros(TypeSize) +
                                 LocalKnown.countMinTrailingZeros()));
    }
  }

  Known.Zero.setLowBits(TrailZ);
  break;
}
case Instruction::PHI: {
  const PHINode *P = cast<PHINode>(I);
  // Handle the case of a simple two-predecessor recurrence PHI.
  // There's a lot more that could theoretically be done here, but
  // this is sufficient to catch some interesting cases.
  if (P->getNumIncomingValues() == 2) {
    for (unsigned i = 0; i != 2; ++i) {
      Value *L = P->getIncomingValue(i);
      Value *R = P->getIncomingValue(!i);
      Operator *LU = dyn_cast<Operator>(L);
      if (!LU)
        continue;
      unsigned Opcode = LU->getOpcode();
      // Check for operations that have the property that if
      // both their operands have low zero bits, the result
      // will have low zero bits.
      if (Opcode == Instruction::Add ||
          Opcode == Instruction::Sub ||
          Opcode == Instruction::And ||
          Opcode == Instruction::Or ||
          Opcode == Instruction::Mul) {
        Value *LL = LU->getOperand(0);
        Value *LR = LU->getOperand(1);
        // Find a recurrence.
        if (LL == I)
          L = LR;
        else if (LR == I)
          L = LL;
        else
          continue; // Check for recurrence with L and R flipped.
        // Ok, we have a PHI of the form L op= R. Check for low
        // zero bits.
        computeKnownBits(R, Known2, Depth + 1, Q);

        // We need to take the minimum number of known bits
        KnownBits Known3(Known);
        computeKnownBits(L, Known3, Depth + 1, Q);

        Known.Zero.setLowBits(std::min(Known2.countMinTrailingZeros(),
                                       Known3.countMinTrailingZeros()));

        auto *OverflowOp = dyn_cast<OverflowingBinaryOperator>(LU);
        if (OverflowOp && Q.IIQ.hasNoSignedWrap(OverflowOp)) {
          // If initial value of recurrence is nonnegative, and we are adding
          // a nonnegative number with nsw, the result can only be nonnegative
          // or poison value regardless of the number of times we execute the
          // add in phi recurrence. If initial value is negative and we are
          // adding a negative number with nsw, the result can only be
          // negative or poison value. Similar arguments apply to sub and mul.
          //
          // (add non-negative, non-negative) --> non-negative
          // (add negative, negative) --> negative
          if (Opcode == Instruction::Add) {
            if (Known2.isNonNegative() && Known3.isNonNegative())
              Known.makeNonNegative();
            else if (Known2.isNegative() && Known3.isNegative())
              Known.makeNegative();
          }

          // (sub nsw non-negative, negative) --> non-negative
          // (sub nsw negative, non-negative) --> negative
          else if (Opcode == Instruction::Sub && LL == I) {
            if (Known2.isNonNegative() && Known3.isNegative())
              Known.makeNonNegative();
            else if (Known2.isNegative() && Known3.isNonNegative())
              Known.makeNegative();
          }

          // (mul nsw non-negative, non-negative) --> non-negative
          else if (Opcode == Instruction::Mul && Known2.isNonNegative() &&
                   Known3.isNonNegative())
            Known.makeNonNegative();
        }

        break;
      }
    }
  }

  // Unreachable blocks may have zero-operand PHI nodes.
  if (P->getNumIncomingValues() == 0)
    break;

  // Otherwise take the unions of the known bit sets of the operands,
  // taking conservative care to avoid excessive recursion.
  if (Depth < MaxDepth - 1 && !Known.Zero && !Known.One) {
    // Skip if every incoming value references to ourself.
    if (dyn_cast_or_null<UndefValue>(P->hasConstantValue()))
      break;

    Known.Zero.setAllBits();
    Known.One.setAllBits();
    for (Value *IncValue : P->incoming_values()) {
      // Skip direct self references.
      if (IncValue == P) continue;

      Known2 = KnownBits(BitWidth);
      // Recurse, but cap the recursion to one level, because we don't
      // want to waste time spinning around in loops.
      computeKnownBits(IncValue, Known2, MaxDepth - 1, Q);
      Known.Zero &= Known2.Zero;
      Known.One &= Known2.One;
      // If all bits have been ruled out, there's no need to check
      // more operands.
      if (!Known.Zero && !Known.One)
        break;
    }
  }
  break;
}
case Instruction::Call:
case Instruction::Invoke:
  // If range metadata is attached to this call, set known bits from that,
  // and then intersect with known bits based on other properties of the
  // function.
  if (MDNode *MD =
          Q.IIQ.getMetadata(cast<Instruction>(I), LLVMContext::MD_range))
    computeKnownBitsFromRangeMetadata(*MD, Known);
  if (const Value *RV = ImmutableCallSite(I).getReturnedArgOperand()) {
    computeKnownBits(RV, Known2, Depth + 1, Q);
    Known.Zero |= Known2.Zero;
    Known.One |= Known2.One;
  }
  if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
    switch (II->getIntrinsicID()) {
    default: break;
    case Intrinsic::bitreverse:
      computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
      Known.Zero |= Known2.Zero.reverseBits();
      Known.One |= Known2.One.reverseBits();
      break;
    case Intrinsic::bswap:
      computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
      Known.Zero |= Known2.Zero.byteSwap();
      Known.One |= Known2.One.byteSwap();
      break;
    case Intrinsic::ctlz: {
      computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
      // If we have a known 1, its position is our upper bound.
      unsigned PossibleLZ = Known2.One.countLeadingZeros();
      // If this call is undefined for 0, the result will be less than 2^n.
      if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext()))
        PossibleLZ = std::min(PossibleLZ, BitWidth - 1);
      unsigned LowBits = Log2_32(PossibleLZ)+1;
      Known.Zero.setBitsFrom(LowBits);
      break;
    }
    case Intrinsic::cttz: {
      computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
      // If we have a known 1, its position is our upper bound.
      unsigned PossibleTZ = Known2.One.countTrailingZeros();
      // If this call is undefined for 0, the result will be less than 2^n.
      if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext()))
        PossibleTZ = std::min(PossibleTZ, BitWidth - 1);
      unsigned LowBits = Log2_32(PossibleTZ)+1;
      Known.Zero.setBitsFrom(LowBits);
      break;
    }
    case Intrinsic::ctpop: {
      computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
      // We can bound the space the count needs.  Also, bits known to be zero
      // can't contribute to the population.
      unsigned BitsPossiblySet = Known2.countMaxPopulation();
      unsigned LowBits = Log2_32(BitsPossiblySet)+1;
      Known.Zero.setBitsFrom(LowBits);
      // TODO: we could bound KnownOne using the lower bound on the number
      // of bits which might be set provided by popcnt KnownOne2.
      break;
    }
    case Intrinsic::fshr:
    case Intrinsic::fshl: {
      const APInt *SA;
      if (!match(I->getOperand(2), m_APInt(SA)))
        break;

      // Normalize to funnel shift left.
      uint64_t ShiftAmt = SA->urem(BitWidth);
      if (II->getIntrinsicID() == Intrinsic::fshr)
        ShiftAmt = BitWidth - ShiftAmt;

      KnownBits Known3(Known);
      computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
      computeKnownBits(I->getOperand(1), Known3, Depth + 1, Q);

      Known.Zero =
          Known2.Zero.shl(ShiftAmt) | Known3.Zero.lshr(BitWidth - ShiftAmt);
      Known.One =
          Known2.One.shl(ShiftAmt) | Known3.One.lshr(BitWidth - ShiftAmt);
      break;
    }
    case Intrinsic::uadd_sat:
    case Intrinsic::usub_sat: {
      bool IsAdd = II->getIntrinsicID() == Intrinsic::uadd_sat;
      computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
      computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);

      // Add: Leading ones of either operand are preserved.
      // Sub: Leading zeros of LHS and leading ones of RHS are preserved
      // as leading zeros in the result.
      unsigned LeadingKnown;
      if (IsAdd)
        LeadingKnown = std::max(Known.countMinLeadingOnes(),
                                Known2.countMinLeadingOnes());
      else
        LeadingKnown = std::max(Known.countMinLeadingZeros(),
                                Known2.countMinLeadingOnes());

      Known = KnownBits::computeForAddSub(
          IsAdd, /* NSW */ false, Known, Known2);

      // We select between the operation result and all-ones/zero
      // respectively, so we can preserve known ones/zeros.
      if (IsAdd) {
        Known.One.setHighBits(LeadingKnown);
        Known.Zero.clearAllBits();
      } else {
        Known.Zero.setHighBits(LeadingKnown);
        Known.One.clearAllBits();
      }
      break;
    }
    case Intrinsic::x86_sse42_crc32_64_64:
      Known.Zero.setBitsFrom(32);
      break;
    }
  }
  break;
case Instruction::ExtractElement:
  // Look through extract element. At the moment we keep this simple and skip
  // tracking the specific element. But at least we might find information
  // valid for all elements of the vector (for example if vector is sign
  // extended, shifted, etc).
  computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
  break;
case Instruction::ExtractValue:
  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I->getOperand(0))) {
    const ExtractValueInst *EVI = cast<ExtractValueInst>(I);
    if (EVI->getNumIndices() != 1) break;
    if (EVI->getIndices()[0] == 0) {
      switch (II->getIntrinsicID()) {
      default: break;
      case Intrinsic::uadd_with_overflow:
      case Intrinsic::sadd_with_overflow:
        computeKnownBitsAddSub(true, II->getArgOperand(0),
                               II->getArgOperand(1), false, Known, Known2,
                               Depth, Q);
        break;
      case Intrinsic::usub_with_overflow:
      case Intrinsic::ssub_with_overflow:
        computeKnownBitsAddSub(false, II->getArgOperand(0),
                               II->getArgOperand(1), false, Known, Known2,
                               Depth, Q);
        break;
      case Intrinsic::umul_with_overflow:
      case Intrinsic::smul_with_overflow:
        computeKnownBitsMul(II->getArgOperand(0), II->getArgOperand(1), false,
                            Known, Known2, Depth, Q);
        break;
      }
    }
  }
}
1609}

1611/// Determine which bits of V are known to be either zero or one and return
1612/// them.
1613KnownBits computeKnownBits(const Value *V, unsigned Depth, const Query &Q) {
KnownBits Known(getBitWidth(V->getType(), Q.DL));
computeKnownBits(V, Known, Depth, Q);
return Known;
1617}

1619/// Determine which bits of V are known to be either zero or one and return
1620/// them in the Known bit set.
1621///
1622/// NOTE: we cannot consider 'undef' to be "IsZero" here.  The problem is that
1623/// we cannot optimize based on the assumption that it is zero without changing
1624/// it to be an explicit zero.  If we don't change it to zero, other code could
1625/// optimized based on the contradictory assumption that it is non-zero.
1626/// Because instcombine aggressively folds operations with undef args anyway,
1627/// this won't lose us code quality.
1628///
1629/// This function is defined on values with integer type, values with pointer
1630/// type, and vectors of integers.  In the case
1631/// where V is a vector, known zero, and known one values are the
1632/// same width as the vector element, and the bit is set only if it is true
1633/// for all of the elements in the vector.
1634void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth,
                    const Query &Q) {
assert(V && "No Value?")((V && "No Value?") ? static_cast<void> (0) : __assert_fail
 ("V && \"No Value?\"", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1636, __PRETTY_FUNCTION__));
assert(Depth <= MaxDepth && "Limit Search Depth")((Depth <= MaxDepth && "Limit Search Depth") ? static_cast
<void> (0) : __assert_fail ("Depth <= MaxDepth && \"Limit Search Depth\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1637, __PRETTY_FUNCTION__));
unsigned BitWidth = Known.getBitWidth();

assert((V->getType()->isIntOrIntVectorTy(BitWidth) ||(((V->getType()->isIntOrIntVectorTy(BitWidth) || V->
getType()->isPtrOrPtrVectorTy()) && "Not integer or pointer type!"
) ? static_cast<void> (0) : __assert_fail ("(V->getType()->isIntOrIntVectorTy(BitWidth) || V->getType()->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1642, __PRETTY_FUNCTION__))
        V->getType()->isPtrOrPtrVectorTy()) &&(((V->getType()->isIntOrIntVectorTy(BitWidth) || V->
getType()->isPtrOrPtrVectorTy()) && "Not integer or pointer type!"
) ? static_cast<void> (0) : __assert_fail ("(V->getType()->isIntOrIntVectorTy(BitWidth) || V->getType()->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1642, __PRETTY_FUNCTION__))
       "Not integer or pointer type!")(((V->getType()->isIntOrIntVectorTy(BitWidth) || V->
getType()->isPtrOrPtrVectorTy()) && "Not integer or pointer type!"
) ? static_cast<void> (0) : __assert_fail ("(V->getType()->isIntOrIntVectorTy(BitWidth) || V->getType()->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1642, __PRETTY_FUNCTION__));

Type *ScalarTy = V->getType()->getScalarType();
unsigned ExpectedWidth = ScalarTy->isPointerTy() ?
  Q.DL.getIndexTypeSizeInBits(ScalarTy) : Q.DL.getTypeSizeInBits(ScalarTy);
assert(ExpectedWidth == BitWidth && "V and Known should have same BitWidth")((ExpectedWidth == BitWidth && "V and Known should have same BitWidth"
) ? static_cast<void> (0) : __assert_fail ("ExpectedWidth == BitWidth && \"V and Known should have same BitWidth\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1647, __PRETTY_FUNCTION__));
(void)BitWidth;
(void)ExpectedWidth;

const APInt *C;
if (match(V, m_APInt(C))) {
  // We know all of the bits for a scalar constant or a splat vector constant!
  Known.One = *C;
  Known.Zero = ~Known.One;
  return;
}
// Null and aggregate-zero are all-zeros.
if (isa<ConstantPointerNull>(V) || isa<ConstantAggregateZero>(V)) {
  Known.setAllZero();
  return;
}
// Handle a constant vector by taking the intersection of the known bits of
// each element.
if (const ConstantDataSequential *CDS = dyn_cast<ConstantDataSequential>(V)) {
  // We know that CDS must be a vector of integers. Take the intersection of
  // each element.
  Known.Zero.setAllBits(); Known.One.setAllBits();
  for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
    APInt Elt = CDS->getElementAsAPInt(i);
    Known.Zero &= ~Elt;
    Known.One &= Elt;
  }
  return;
}

if (const auto *CV = dyn_cast<ConstantVector>(V)) {
  // We know that CV must be a vector of integers. Take the intersection of
  // each element.
  Known.Zero.setAllBits(); Known.One.setAllBits();
  for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) {
    Constant *Element = CV->getAggregateElement(i);
    auto *ElementCI = dyn_cast_or_null<ConstantInt>(Element);
    if (!ElementCI) {
      Known.resetAll();
      return;
    }
    const APInt &Elt = ElementCI->getValue();
    Known.Zero &= ~Elt;
    Known.One &= Elt;
  }
  return;
}

// Start out not knowing anything.
Known.resetAll();

// We can't imply anything about undefs.
if (isa<UndefValue>(V))
  return;

// There's no point in looking through other users of ConstantData for
// assumptions.  Confirm that we've handled them all.
assert(!isa<ConstantData>(V) && "Unhandled constant data!")((!isa<ConstantData>(V) && "Unhandled constant data!"
) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantData>(V) && \"Unhandled constant data!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1704, __PRETTY_FUNCTION__));

// Limit search depth.
// All recursive calls that increase depth must come after this.
if (Depth == MaxDepth)
  return;

// A weak GlobalAlias is totally unknown. A non-weak GlobalAlias has
// the bits of its aliasee.
if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
  if (!GA->isInterposable())
    computeKnownBits(GA->getAliasee(), Known, Depth + 1, Q);
  return;
}

if (const Operator *I = dyn_cast<Operator>(V))
  computeKnownBitsFromOperator(I, Known, Depth, Q);

// Aligned pointers have trailing zeros - refine Known.Zero set
if (V->getType()->isPointerTy()) {
  unsigned Align = V->getPointerAlignment(Q.DL);
  if (Align)
    Known.Zero.setLowBits(countTrailingZeros(Align));
}

// computeKnownBitsFromAssume strictly refines Known.
// Therefore, we run them after computeKnownBitsFromOperator.

// Check whether a nearby assume intrinsic can determine some known bits.
computeKnownBitsFromAssume(V, Known, Depth, Q);

assert((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?")(((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?"
) ? static_cast<void> (0) : __assert_fail ("(Known.Zero & Known.One) == 0 && \"Bits known to be one AND zero?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1735, __PRETTY_FUNCTION__));
1736}

1738/// Return true if the given value is known to have exactly one
1739/// bit set when defined. For vectors return true if every element is known to
1740/// be a power of two when defined. Supports values with integer or pointer
1741/// types and vectors of integers.
1742bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth,
                          const Query &Q) {
assert(Depth <= MaxDepth && "Limit Search Depth")((Depth <= MaxDepth && "Limit Search Depth") ? static_cast
<void> (0) : __assert_fail ("Depth <= MaxDepth && \"Limit Search Depth\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1744, __PRETTY_FUNCTION__));

// Attempt to match against constants.
if (OrZero && match(V, m_Power2OrZero()))
    return true;
if (match(V, m_Power2()))
    return true;

// 1 << X is clearly a power of two if the one is not shifted off the end.  If
// it is shifted off the end then the result is undefined.
if (match(V, m_Shl(m_One(), m_Value())))
  return true;

// (signmask) >>l X is clearly a power of two if the one is not shifted off
// the bottom.  If it is shifted off the bottom then the result is undefined.
if (match(V, m_LShr(m_SignMask(), m_Value())))
  return true;

// The remaining tests are all recursive, so bail out if we hit the limit.
if (Depth++ == MaxDepth)
  return false;

Value *X = nullptr, *Y = nullptr;
// A shift left or a logical shift right of a power of two is a power of two
// or zero.
if (OrZero && (match(V, m_Shl(m_Value(X), m_Value())) ||
               match(V, m_LShr(m_Value(X), m_Value()))))
  return isKnownToBeAPowerOfTwo(X, /*OrZero*/ true, Depth, Q);

if (const ZExtInst *ZI = dyn_cast<ZExtInst>(V))
  return isKnownToBeAPowerOfTwo(ZI->getOperand(0), OrZero, Depth, Q);

if (const SelectInst *SI = dyn_cast<SelectInst>(V))
  return isKnownToBeAPowerOfTwo(SI->getTrueValue(), OrZero, Depth, Q) &&
         isKnownToBeAPowerOfTwo(SI->getFalseValue(), OrZero, Depth, Q);

if (OrZero && match(V, m_And(m_Value(X), m_Value(Y)))) {
  // A power of two and'd with anything is a power of two or zero.
  if (isKnownToBeAPowerOfTwo(X, /*OrZero*/ true, Depth, Q) ||
      isKnownToBeAPowerOfTwo(Y, /*OrZero*/ true, Depth, Q))
    return true;
  // X & (-X) is always a power of two or zero.
  if (match(X, m_Neg(m_Specific(Y))) || match(Y, m_Neg(m_Specific(X))))
    return true;
  return false;
}

// Adding a power-of-two or zero to the same power-of-two or zero yields
// either the original power-of-two, a larger power-of-two or zero.
if (match(V, m_Add(m_Value(X), m_Value(Y)))) {
  const OverflowingBinaryOperator *VOBO = cast<OverflowingBinaryOperator>(V);
  if (OrZero || Q.IIQ.hasNoUnsignedWrap(VOBO) ||
      Q.IIQ.hasNoSignedWrap(VOBO)) {
    if (match(X, m_And(m_Specific(Y), m_Value())) ||
        match(X, m_And(m_Value(), m_Specific(Y))))
      if (isKnownToBeAPowerOfTwo(Y, OrZero, Depth, Q))
        return true;
    if (match(Y, m_And(m_Specific(X), m_Value())) ||
        match(Y, m_And(m_Value(), m_Specific(X))))
      if (isKnownToBeAPowerOfTwo(X, OrZero, Depth, Q))
        return true;

    unsigned BitWidth = V->getType()->getScalarSizeInBits();
    KnownBits LHSBits(BitWidth);
    computeKnownBits(X, LHSBits, Depth, Q);

    KnownBits RHSBits(BitWidth);
    computeKnownBits(Y, RHSBits, Depth, Q);
    // If i8 V is a power of two or zero:
    //  ZeroBits: 1 1 1 0 1 1 1 1
    // ~ZeroBits: 0 0 0 1 0 0 0 0
    if ((~(LHSBits.Zero & RHSBits.Zero)).isPowerOf2())
      // If OrZero isn't set, we cannot give back a zero result.
      // Make sure either the LHS or RHS has a bit set.
      if (OrZero || RHSBits.One.getBoolValue() || LHSBits.One.getBoolValue())
        return true;
  }
}

// An exact divide or right shift can only shift off zero bits, so the result
// is a power of two only if the first operand is a power of two and not
// copying a sign bit (sdiv int_min, 2).
if (match(V, m_Exact(m_LShr(m_Value(), m_Value()))) ||
    match(V, m_Exact(m_UDiv(m_Value(), m_Value())))) {
  return isKnownToBeAPowerOfTwo(cast<Operator>(V)->getOperand(0), OrZero,
                                Depth, Q);
}

return false;
1833}

1835/// Test whether a GEP's result is known to be non-null.
1836///
1837/// Uses properties inherent in a GEP to try to determine whether it is known
1838/// to be non-null.
1839///
1840/// Currently this routine does not support vector GEPs.
1841static bool isGEPKnownNonNull(const GEPOperator *GEP, unsigned Depth,
                            const Query &Q) {
const Function *F = nullptr;
if (const Instruction *I = dyn_cast<Instruction>(GEP))
  F = I->getFunction();

if (!GEP->isInBounds() ||
    NullPointerIsDefined(F, GEP->getPointerAddressSpace()))
  return false;

// FIXME: Support vector-GEPs.
assert(GEP->getType()->isPointerTy() && "We only support plain pointer GEP")((GEP->getType()->isPointerTy() && "We only support plain pointer GEP"
) ? static_cast<void> (0) : __assert_fail ("GEP->getType()->isPointerTy() && \"We only support plain pointer GEP\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1852, __PRETTY_FUNCTION__));

// If the base pointer is non-null, we cannot walk to a null address with an
// inbounds GEP in address space zero.
if (isKnownNonZero(GEP->getPointerOperand(), Depth, Q))
  return true;

// Walk the GEP operands and see if any operand introduces a non-zero offset.
// If so, then the GEP cannot produce a null pointer, as doing so would
// inherently violate the inbounds contract within address space zero.
for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP);
     GTI != GTE; ++GTI) {
  // Struct types are easy -- they must always be indexed by a constant.
  if (StructType *STy = GTI.getStructTypeOrNull()) {
    ConstantInt *OpC = cast<ConstantInt>(GTI.getOperand());
    unsigned ElementIdx = OpC->getZExtValue();
    const StructLayout *SL = Q.DL.getStructLayout(STy);
    uint64_t ElementOffset = SL->getElementOffset(ElementIdx);
    if (ElementOffset > 0)
      return true;
    continue;
  }

  // If we have a zero-sized type, the index doesn't matter. Keep looping.
  if (Q.DL.getTypeAllocSize(GTI.getIndexedType()) == 0)
    continue;

  // Fast path the constant operand case both for efficiency and so we don't
  // increment Depth when just zipping down an all-constant GEP.
  if (ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand())) {
    if (!OpC->isZero())
      return true;
    continue;
  }

  // We post-increment Depth here because while isKnownNonZero increments it
  // as well, when we pop back up that increment won't persist. We don't want
  // to recurse 10k times just because we have 10k GEP operands. We don't
  // bail completely out because we want to handle constant GEPs regardless
  // of depth.
  if (Depth++ >= MaxDepth)
    continue;

  if (isKnownNonZero(GTI.getOperand(), Depth, Q))
    return true;
}

return false;
1900}

1902static bool isKnownNonNullFromDominatingCondition(const Value *V,
                                                const Instruction *CtxI,
                                                const DominatorTree *DT) {
assert(V->getType()->isPointerTy() && "V must be pointer type")((V->getType()->isPointerTy() && "V must be pointer type"
) ? static_cast<void> (0) : __assert_fail ("V->getType()->isPointerTy() && \"V must be pointer type\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1905, __PRETTY_FUNCTION__));
assert(!isa<ConstantData>(V) && "Did not expect ConstantPointerNull")((!isa<ConstantData>(V) && "Did not expect ConstantPointerNull"
) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantData>(V) && \"Did not expect ConstantPointerNull\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1906, __PRETTY_FUNCTION__));

if (!CtxI || !DT)
  return false;

unsigned NumUsesExplored = 0;
for (auto *U : V->users()) {
  // Avoid massive lists
  if (NumUsesExplored >= DomConditionsMaxUses)
    break;
  NumUsesExplored++;

  // If the value is used as an argument to a call or invoke, then argument
  // attributes may provide an answer about null-ness.
  if (auto CS = ImmutableCallSite(U))
    if (auto *CalledFunc = CS.getCalledFunction())
      for (const Argument &Arg : CalledFunc->args())
        if (CS.getArgOperand(Arg.getArgNo()) == V &&
            Arg.hasNonNullAttr() && DT->dominates(CS.getInstruction(), CtxI))
          return true;

  // Consider only compare instructions uniquely controlling a branch
  CmpInst::Predicate Pred;
  if (!match(const_cast<User *>(U),
             m_c_ICmp(Pred, m_Specific(V), m_Zero())) ||
      (Pred != ICmpInst::ICMP_EQ && Pred != ICmpInst::ICMP_NE))
    continue;

  SmallVector<const User *, 4> WorkList;
  SmallPtrSet<const User *, 4> Visited;
  for (auto *CmpU : U->users()) {
    assert(WorkList.empty() && "Should be!")((WorkList.empty() && "Should be!") ? static_cast<
void> (0) : __assert_fail ("WorkList.empty() && \"Should be!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1937, __PRETTY_FUNCTION__));
    if (Visited.insert(CmpU).second)
      WorkList.push_back(CmpU);

    while (!WorkList.empty()) {
      auto *Curr = WorkList.pop_back_val();

      // If a user is an AND, add all its users to the work list. We only
      // propagate "pred != null" condition through AND because it is only
      // correct to assume that all conditions of AND are met in true branch.
      // TODO: Support similar logic of OR and EQ predicate?
      if (Pred == ICmpInst::ICMP_NE)
        if (auto *BO = dyn_cast<BinaryOperator>(Curr))
          if (BO->getOpcode() == Instruction::And) {
            for (auto *BOU : BO->users())
              if (Visited.insert(BOU).second)
                WorkList.push_back(BOU);
            continue;
          }

      if (const BranchInst *BI = dyn_cast<BranchInst>(Curr)) {
        assert(BI->isConditional() && "uses a comparison!")((BI->isConditional() && "uses a comparison!") ? static_cast
<void> (0) : __assert_fail ("BI->isConditional() && \"uses a comparison!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1958, __PRETTY_FUNCTION__));

        BasicBlock *NonNullSuccessor =
            BI->getSuccessor(Pred == ICmpInst::ICMP_EQ ? 1 : 0);
        BasicBlockEdge Edge(BI->getParent(), NonNullSuccessor);
        if (Edge.isSingleEdge() && DT->dominates(Edge, CtxI->getParent()))
          return true;
      } else if (Pred == ICmpInst::ICMP_NE && isGuard(Curr) &&
                 DT->dominates(cast<Instruction>(Curr), CtxI)) {
        return true;
      }
    }
  }
}

return false;
1974}

1976/// Does the 'Range' metadata (which must be a valid MD_range operand list)
1977/// ensure that the value it's attached to is never Value?  'RangeType' is
1978/// is the type of the value described by the range.
1979static bool rangeMetadataExcludesValue(const MDNode* Ranges, const APInt& Value) {
const unsigned NumRanges = Ranges->getNumOperands() / 2;
assert(NumRanges >= 1)((NumRanges >= 1) ? static_cast<void> (0) : __assert_fail
 ("NumRanges >= 1", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 1981, __PRETTY_FUNCTION__));
for (unsigned i = 0; i < NumRanges; ++i) {
  ConstantInt *Lower =
      mdconst::extract<ConstantInt>(Ranges->getOperand(2 * i + 0));
  ConstantInt *Upper =
      mdconst::extract<ConstantInt>(Ranges->getOperand(2 * i + 1));
  ConstantRange Range(Lower->getValue(), Upper->getValue());
  if (Range.contains(Value))
    return false;
}
return true;
1992}

1994/// Return true if the given value is known to be non-zero when defined. For
1995/// vectors, return true if every element is known to be non-zero when
1996/// defined. For pointers, if the context instruction and dominator tree are
1997/// specified, perform context-sensitive analysis and return true if the
1998/// pointer couldn't possibly be null at the specified instruction.
1999/// Supports values with integer or pointer type and vectors of integers.
2000bool isKnownNonZero(const Value *V, unsigned Depth, const Query &Q) {
if (auto *C = dyn_cast<Constant>(V)) {
  if (C->isNullValue())
    return false;
  if (isa<ConstantInt>(C))
    // Must be non-zero due to null test above.
    return true;

  if (auto *CE = dyn_cast<ConstantExpr>(C)) {
    // See the comment for IntToPtr/PtrToInt instructions below.
    if (CE->getOpcode() == Instruction::IntToPtr ||
        CE->getOpcode() == Instruction::PtrToInt)
      if (Q.DL.getTypeSizeInBits(CE->getOperand(0)->getType()) <=
          Q.DL.getTypeSizeInBits(CE->getType()))
        return isKnownNonZero(CE->getOperand(0), Depth, Q);
  }

  // For constant vectors, check that all elements are undefined or known
  // non-zero to determine that the whole vector is known non-zero.
  if (auto *VecTy = dyn_cast<VectorType>(C->getType())) {
    for (unsigned i = 0, e = VecTy->getNumElements(); i != e; ++i) {
      Constant *Elt = C->getAggregateElement(i);
      if (!Elt || Elt->isNullValue())
        return false;
      if (!isa<UndefValue>(Elt) && !isa<ConstantInt>(Elt))
        return false;
    }
    return true;
  }

  // A global variable in address space 0 is non null unless extern weak
  // or an absolute symbol reference. Other address spaces may have null as a
  // valid address for a global, so we can't assume anything.
  if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
    if (!GV->isAbsoluteSymbolRef() && !GV->hasExternalWeakLinkage() &&
        GV->getType()->getAddressSpace() == 0)
      return true;
  } else
    return false;
}

if (auto *I = dyn_cast<Instruction>(V)) {
  if (MDNode *Ranges = Q.IIQ.getMetadata(I, LLVMContext::MD_range)) {
    // If the possible ranges don't contain zero, then the value is
    // definitely non-zero.
    if (auto *Ty = dyn_cast<IntegerType>(V->getType())) {
      const APInt ZeroValue(Ty->getBitWidth(), 0);
      if (rangeMetadataExcludesValue(Ranges, ZeroValue))
        return true;
    }
  }
}

// Some of the tests below are recursive, so bail out if we hit the limit.
if (Depth++ >= MaxDepth)
  return false;

// Check for pointer simplifications.
if (V->getType()->isPointerTy()) {
  // Alloca never returns null, malloc might.
  if (isa<AllocaInst>(V) && Q.DL.getAllocaAddrSpace() == 0)
    return true;

  // A byval, inalloca, or nonnull argument is never null.
  if (const Argument *A = dyn_cast<Argument>(V))
    if (A->hasByValOrInAllocaAttr() || A->hasNonNullAttr())
      return true;

  // A Load tagged with nonnull metadata is never null.
  if (const LoadInst *LI = dyn_cast<LoadInst>(V))
    if (Q.IIQ.getMetadata(LI, LLVMContext::MD_nonnull))
      return true;

  if (const auto *Call = dyn_cast<CallBase>(V)) {
    if (Call->isReturnNonNull())
      return true;
    if (const auto *RP = getArgumentAliasingToReturnedPointer(Call, true))
      return isKnownNonZero(RP, Depth, Q);
  }
}


// Check for recursive pointer simplifications.
if (V->getType()->isPointerTy()) {
  if (isKnownNonNullFromDominatingCondition(V, Q.CxtI, Q.DT))
    return true;

  // Look through bitcast operations, GEPs, and int2ptr instructions as they
  // do not alter the value, or at least not the nullness property of the
  // value, e.g., int2ptr is allowed to zero/sign extend the value.
  //
  // Note that we have to take special care to avoid looking through
  // truncating casts, e.g., int2ptr/ptr2int with appropriate sizes, as well
  // as casts that can alter the value, e.g., AddrSpaceCasts.
  if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V))
    if (isGEPKnownNonNull(GEP, Depth, Q))
      return true;

  if (auto *BCO = dyn_cast<BitCastOperator>(V))
    return isKnownNonZero(BCO->getOperand(0), Depth, Q);

  if (auto *I2P = dyn_cast<IntToPtrInst>(V))
    if (Q.DL.getTypeSizeInBits(I2P->getSrcTy()) <=
        Q.DL.getTypeSizeInBits(I2P->getDestTy()))
      return isKnownNonZero(I2P->getOperand(0), Depth, Q);
}

// Similar to int2ptr above, we can look through ptr2int here if the cast
// is a no-op or an extend and not a truncate.
if (auto *P2I = dyn_cast<PtrToIntInst>(V))
  if (Q.DL.getTypeSizeInBits(P2I->getSrcTy()) <=
      Q.DL.getTypeSizeInBits(P2I->getDestTy()))
    return isKnownNonZero(P2I->getOperand(0), Depth, Q);

unsigned BitWidth = getBitWidth(V->getType()->getScalarType(), Q.DL);

// X | Y != 0 if X != 0 or Y != 0.
Value *X = nullptr, *Y = nullptr;
if (match(V, m_Or(m_Value(X), m_Value(Y))))
  return isKnownNonZero(X, Depth, Q) || isKnownNonZero(Y, Depth, Q);

// ext X != 0 if X != 0.
if (isa<SExtInst>(V) || isa<ZExtInst>(V))
  return isKnownNonZero(cast<Instruction>(V)->getOperand(0), Depth, Q);

// shl X, Y != 0 if X is odd.  Note that the value of the shift is undefined
// if the lowest bit is shifted off the end.
if (match(V, m_Shl(m_Value(X), m_Value(Y)))) {
  // shl nuw can't remove any non-zero bits.
  const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V);
  if (Q.IIQ.hasNoUnsignedWrap(BO))
    return isKnownNonZero(X, Depth, Q);

  KnownBits Known(BitWidth);
  computeKnownBits(X, Known, Depth, Q);
  if (Known.One[0])
    return true;
}
// shr X, Y != 0 if X is negative.  Note that the value of the shift is not
// defined if the sign bit is shifted off the end.
else if (match(V, m_Shr(m_Value(X), m_Value(Y)))) {
  // shr exact can only shift out zero bits.
  const PossiblyExactOperator *BO = cast<PossiblyExactOperator>(V);
  if (BO->isExact())
    return isKnownNonZero(X, Depth, Q);

  KnownBits Known = computeKnownBits(X, Depth, Q);
  if (Known.isNegative())
    return true;

  // If the shifter operand is a constant, and all of the bits shifted
  // out are known to be zero, and X is known non-zero then at least one
  // non-zero bit must remain.
  if (ConstantInt *Shift = dyn_cast<ConstantInt>(Y)) {
    auto ShiftVal = Shift->getLimitedValue(BitWidth - 1);
    // Is there a known one in the portion not shifted out?
    if (Known.countMaxLeadingZeros() < BitWidth - ShiftVal)
      return true;
    // Are all the bits to be shifted out known zero?
    if (Known.countMinTrailingZeros() >= ShiftVal)
      return isKnownNonZero(X, Depth, Q);
  }
}
// div exact can only produce a zero if the dividend is zero.
else if (match(V, m_Exact(m_IDiv(m_Value(X), m_Value())))) {
  return isKnownNonZero(X, Depth, Q);
}
// X + Y.
else if (match(V, m_Add(m_Value(X), m_Value(Y)))) {
  KnownBits XKnown = computeKnownBits(X, Depth, Q);
  KnownBits YKnown = computeKnownBits(Y, Depth, Q);

  // If X and Y are both non-negative (as signed values) then their sum is not
  // zero unless both X and Y are zero.
  if (XKnown.isNonNegative() && YKnown.isNonNegative())
    if (isKnownNonZero(X, Depth, Q) || isKnownNonZero(Y, Depth, Q))
      return true;

  // If X and Y are both negative (as signed values) then their sum is not
  // zero unless both X and Y equal INT_MIN.
  if (XKnown.isNegative() && YKnown.isNegative()) {
    APInt Mask = APInt::getSignedMaxValue(BitWidth);
    // The sign bit of X is set.  If some other bit is set then X is not equal
    // to INT_MIN.
    if (XKnown.One.intersects(Mask))
      return true;
    // The sign bit of Y is set.  If some other bit is set then Y is not equal
    // to INT_MIN.
    if (YKnown.One.intersects(Mask))
      return true;
  }

  // The sum of a non-negative number and a power of two is not zero.
  if (XKnown.isNonNegative() &&
      isKnownToBeAPowerOfTwo(Y, /*OrZero*/ false, Depth, Q))
    return true;
  if (YKnown.isNonNegative() &&
      isKnownToBeAPowerOfTwo(X, /*OrZero*/ false, Depth, Q))
    return true;
}
// X * Y.
else if (match(V, m_Mul(m_Value(X), m_Value(Y)))) {
  const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V);
  // If X and Y are non-zero then so is X * Y as long as the multiplication
  // does not overflow.
  if ((Q.IIQ.hasNoSignedWrap(BO) || Q.IIQ.hasNoUnsignedWrap(BO)) &&
      isKnownNonZero(X, Depth, Q) && isKnownNonZero(Y, Depth, Q))
    return true;
}
// (C ? X : Y) != 0 if X != 0 and Y != 0.
else if (const SelectInst *SI = dyn_cast<SelectInst>(V)) {
  if (isKnownNonZero(SI->getTrueValue(), Depth, Q) &&
      isKnownNonZero(SI->getFalseValue(), Depth, Q))
    return true;
}
// PHI
else if (const PHINode *PN = dyn_cast<PHINode>(V)) {
  // Try and detect a recurrence that monotonically increases from a
  // starting value, as these are common as induction variables.
  if (PN->getNumIncomingValues() == 2) {
    Value *Start = PN->getIncomingValue(0);
    Value *Induction = PN->getIncomingValue(1);
    if (isa<ConstantInt>(Induction) && !isa<ConstantInt>(Start))
      std::swap(Start, Induction);
    if (ConstantInt *C = dyn_cast<ConstantInt>(Start)) {
      if (!C->isZero() && !C->isNegative()) {
        ConstantInt *X;
        if (Q.IIQ.UseInstrInfo &&
            (match(Induction, m_NSWAdd(m_Specific(PN), m_ConstantInt(X))) ||
             match(Induction, m_NUWAdd(m_Specific(PN), m_ConstantInt(X)))) &&
            !X->isNegative())
          return true;
      }
    }
  }
  // Check if all incoming values are non-zero constant.
  bool AllNonZeroConstants = llvm::all_of(PN->operands(), [](Value *V) {
    return isa<ConstantInt>(V) && !cast<ConstantInt>(V)->isZero();
  });
  if (AllNonZeroConstants)
    return true;
}

KnownBits Known(BitWidth);
computeKnownBits(V, Known, Depth, Q);
return Known.One != 0;
2246}

2248/// Return true if V2 == V1 + X, where X is known non-zero.
2249static bool isAddOfNonZero(const Value *V1, const Value *V2, const Query &Q) {
const BinaryOperator *BO = dyn_cast<BinaryOperator>(V1);
if (!BO || BO->getOpcode() != Instruction::Add)
  return false;
Value *Op = nullptr;
if (V2 == BO->getOperand(0))
  Op = BO->getOperand(1);
else if (V2 == BO->getOperand(1))
  Op = BO->getOperand(0);
else
  return false;
return isKnownNonZero(Op, 0, Q);
2261}

2263/// Return true if it is known that V1 != V2.
2264static bool isKnownNonEqual(const Value *V1, const Value *V2, const Query &Q) {
if (V1 == V2)
  return false;
if (V1->getType() != V2->getType())
  // We can't look through casts yet.
  return false;
if (isAddOfNonZero(V1, V2, Q) || isAddOfNonZero(V2, V1, Q))
  return true;

if (V1->getType()->isIntOrIntVectorTy()) {
  // Are any known bits in V1 contradictory to known bits in V2? If V1
  // has a known zero where V2 has a known one, they must not be equal.
  KnownBits Known1 = computeKnownBits(V1, 0, Q);
  KnownBits Known2 = computeKnownBits(V2, 0, Q);

  if (Known1.Zero.intersects(Known2.One) ||
      Known2.Zero.intersects(Known1.One))
    return true;
}
return false;
2284}

2286/// Return true if 'V & Mask' is known to be zero.  We use this predicate to
2287/// simplify operations downstream. Mask is known to be zero for bits that V
2288/// cannot have.
2289///
2290/// This function is defined on values with integer type, values with pointer
2291/// type, and vectors of integers.  In the case
2292/// where V is a vector, the mask, known zero, and known one values are the
2293/// same width as the vector element, and the bit is set only if it is true
2294/// for all of the elements in the vector.
2295bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth,
                     const Query &Q) {
KnownBits Known(Mask.getBitWidth());
computeKnownBits(V, Known, Depth, Q);
return Mask.isSubsetOf(Known.Zero);
2300}

2302// Match a signed min+max clamp pattern like smax(smin(In, CHigh), CLow).
2303// Returns the input and lower/upper bounds.
2304static bool isSignedMinMaxClamp(const Value *Select, const Value *&In,
                              const APInt *&CLow, const APInt *&CHigh) {
assert(isa<Operator>(Select) &&((isa<Operator>(Select) && cast<Operator>
(Select)->getOpcode() == Instruction::Select && "Input should be a Select!"
) ? static_cast<void> (0) : __assert_fail ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 2308, __PRETTY_FUNCTION__))
       cast<Operator>(Select)->getOpcode() == Instruction::Select &&((isa<Operator>(Select) && cast<Operator>
(Select)->getOpcode() == Instruction::Select && "Input should be a Select!"
) ? static_cast<void> (0) : __assert_fail ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 2308, __PRETTY_FUNCTION__))
       "Input should be a Select!")((isa<Operator>(Select) && cast<Operator>
(Select)->getOpcode() == Instruction::Select && "Input should be a Select!"
) ? static_cast<void> (0) : __assert_fail ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 2308, __PRETTY_FUNCTION__));

const Value *LHS, *RHS, *LHS2, *RHS2;
SelectPatternFlavor SPF = matchSelectPattern(Select, LHS, RHS).Flavor;
if (SPF != SPF_SMAX && SPF != SPF_SMIN)
  return false;

if (!match(RHS, m_APInt(CLow)))
  return false;

SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor;
if (getInverseMinMaxFlavor(SPF) != SPF2)
  return false;

if (!match(RHS2, m_APInt(CHigh)))
  return false;

if (SPF == SPF_SMIN)
  std::swap(CLow, CHigh);

In = LHS2;
return CLow->sle(*CHigh);
2330}

2332/// For vector constants, loop over the elements and find the constant with the
2333/// minimum number of sign bits. Return 0 if the value is not a vector constant
2334/// or if any element was not analyzed; otherwise, return the count for the
2335/// element with the minimum number of sign bits.
2336static unsigned computeNumSignBitsVectorConstant(const Value *V,
                                               unsigned TyBits) {
const auto *CV = dyn_cast<Constant>(V);
if (!CV || !CV->getType()->isVectorTy())
  return 0;

unsigned MinSignBits = TyBits;
unsigned NumElts = CV->getType()->getVectorNumElements();
for (unsigned i = 0; i != NumElts; ++i) {
  // If we find a non-ConstantInt, bail out.
  auto *Elt = dyn_cast_or_null<ConstantInt>(CV->getAggregateElement(i));
  if (!Elt)
    return 0;

  MinSignBits = std::min(MinSignBits, Elt->getValue().getNumSignBits());
}

return MinSignBits;
2354}

2356static unsigned ComputeNumSignBitsImpl(const Value *V, unsigned Depth,
                                     const Query &Q);

2359static unsigned ComputeNumSignBits(const Value *V, unsigned Depth,
                                 const Query &Q) {
unsigned Result = ComputeNumSignBitsImpl(V, Depth, Q);
assert(Result > 0 && "At least one sign bit needs to be present!")((Result > 0 && "At least one sign bit needs to be present!"
) ? static_cast<void> (0) : __assert_fail ("Result > 0 && \"At least one sign bit needs to be present!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 2362, __PRETTY_FUNCTION__));
return Result;
2364}

2366/// Return the number of times the sign bit of the register is replicated into
2367/// the other bits. We know that at least 1 bit is always equal to the sign bit
2368/// (itself), but other cases can give us information. For example, immediately
2369/// after an "ashr X, 2", we know that the top 3 bits are all equal to each
2370/// other, so we return 3. For vectors, return the number of sign bits for the
2371/// vector element with the minimum number of known sign bits.
2372static unsigned ComputeNumSignBitsImpl(const Value *V, unsigned Depth,
                                     const Query &Q) {
assert(Depth <= MaxDepth && "Limit Search Depth")((Depth <= MaxDepth && "Limit Search Depth") ? static_cast
<void> (0) : __assert_fail ("Depth <= MaxDepth && \"Limit Search Depth\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 2374, __PRETTY_FUNCTION__));

// We return the minimum number of sign bits that are guaranteed to be present
// in V, so for undef we have to conservatively return 1.  We don't have the
// same behavior for poison though -- that's a FIXME today.

Type *ScalarTy = V->getType()->getScalarType();
unsigned TyBits = ScalarTy->isPointerTy() ?
  Q.DL.getIndexTypeSizeInBits(ScalarTy) :
  Q.DL.getTypeSizeInBits(ScalarTy);

unsigned Tmp, Tmp2;
unsigned FirstAnswer = 1;

// Note that ConstantInt is handled by the general computeKnownBits case
// below.

if (Depth == MaxDepth)
  return 1;  // Limit search depth.

const Operator *U = dyn_cast<Operator>(V);
switch (Operator::getOpcode(V)) {
default: break;
case Instruction::SExt:
  Tmp = TyBits - U->getOperand(0)->getType()->getScalarSizeInBits();
  return ComputeNumSignBits(U->getOperand(0), Depth + 1, Q) + Tmp;

case Instruction::SDiv: {
  const APInt *Denominator;
  // sdiv X, C -> adds log(C) sign bits.
  if (match(U->getOperand(1), m_APInt(Denominator))) {

    // Ignore non-positive denominator.
    if (!Denominator->isStrictlyPositive())
      break;

    // Calculate the incoming numerator bits.
    unsigned NumBits = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);

    // Add floor(log(C)) bits to the numerator bits.
    return std::min(TyBits, NumBits + Denominator->logBase2());
  }
  break;
}

case Instruction::SRem: {
  const APInt *Denominator;
  // srem X, C -> we know that the result is within [-C+1,C) when C is a
  // positive constant.  This let us put a lower bound on the number of sign
  // bits.
  if (match(U->getOperand(1), m_APInt(Denominator))) {

    // Ignore non-positive denominator.
    if (!Denominator->isStrictlyPositive())
      break;

    // Calculate the incoming numerator bits. SRem by a positive constant
    // can't lower the number of sign bits.
    unsigned NumrBits =
        ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);

    // Calculate the leading sign bit constraints by examining the
    // denominator.  Given that the denominator is positive, there are two
    // cases:
    //
    //  1. the numerator is positive.  The result range is [0,C) and [0,C) u<
    //     (1 << ceilLogBase2(C)).
    //
    //  2. the numerator is negative.  Then the result range is (-C,0] and
    //     integers in (-C,0] are either 0 or >u (-1 << ceilLogBase2(C)).
    //
    // Thus a lower bound on the number of sign bits is `TyBits -
    // ceilLogBase2(C)`.

    unsigned ResBits = TyBits - Denominator->ceilLogBase2();
    return std::max(NumrBits, ResBits);
  }
  break;
}

case Instruction::AShr: {
  Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
  // ashr X, C   -> adds C sign bits.  Vectors too.
  const APInt *ShAmt;
  if (match(U->getOperand(1), m_APInt(ShAmt))) {
    if (ShAmt->uge(TyBits))
      break;  // Bad shift.
    unsigned ShAmtLimited = ShAmt->getZExtValue();
    Tmp += ShAmtLimited;
    if (Tmp > TyBits) Tmp = TyBits;
  }
  return Tmp;
}
case Instruction::Shl: {
  const APInt *ShAmt;
  if (match(U->getOperand(1), m_APInt(ShAmt))) {
    // shl destroys sign bits.
    Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
    if (ShAmt->uge(TyBits) ||      // Bad shift.
        ShAmt->uge(Tmp)) break;    // Shifted all sign bits out.
    Tmp2 = ShAmt->getZExtValue();
    return Tmp - Tmp2;
  }
  break;
}
case Instruction::And:
case Instruction::Or:
case Instruction::Xor:    // NOT is handled here.
  // Logical binary ops preserve the number of sign bits at the worst.
  Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
  if (Tmp != 1) {
    Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
    FirstAnswer = std::min(Tmp, Tmp2);
    // We computed what we know about the sign bits as our first
    // answer. Now proceed to the generic code that uses
    // computeKnownBits, and pick whichever answer is better.
  }
  break;

case Instruction::Select: {
  // If we have a clamp pattern, we know that the number of sign bits will be
  // the minimum of the clamp min/max range.
  const Value *X;
  const APInt *CLow, *CHigh;
  if (isSignedMinMaxClamp(U, X, CLow, CHigh))
    return std::min(CLow->getNumSignBits(), CHigh->getNumSignBits());

  Tmp = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
  if (Tmp == 1) break;
  Tmp2 = ComputeNumSignBits(U->getOperand(2), Depth + 1, Q);
  return std::min(Tmp, Tmp2);
}

case Instruction::Add:
  // Add can have at most one carry bit.  Thus we know that the output
  // is, at worst, one more bit than the inputs.
  Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
  if (Tmp == 1) break;

  // Special case decrementing a value (ADD X, -1):
  if (const auto *CRHS = dyn_cast<Constant>(U->getOperand(1)))
    if (CRHS->isAllOnesValue()) {
      KnownBits Known(TyBits);
      computeKnownBits(U->getOperand(0), Known, Depth + 1, Q);

      // If the input is known to be 0 or 1, the output is 0/-1, which is all
      // sign bits set.
      if ((Known.Zero | 1).isAllOnesValue())
        return TyBits;

      // If we are subtracting one from a positive number, there is no carry
      // out of the result.
      if (Known.isNonNegative())
        return Tmp;
    }

  Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
  if (Tmp2 == 1) break;
  return std::min(Tmp, Tmp2)-1;

case Instruction::Sub:
  Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
  if (Tmp2 == 1) break;

  // Handle NEG.
  if (const auto *CLHS = dyn_cast<Constant>(U->getOperand(0)))
    if (CLHS->isNullValue()) {
      KnownBits Known(TyBits);
      computeKnownBits(U->getOperand(1), Known, Depth + 1, Q);
      // If the input is known to be 0 or 1, the output is 0/-1, which is all
      // sign bits set.
      if ((Known.Zero | 1).isAllOnesValue())
        return TyBits;

      // If the input is known to be positive (the sign bit is known clear),
      // the output of the NEG has the same number of sign bits as the input.
      if (Known.isNonNegative())
        return Tmp2;

      // Otherwise, we treat this like a SUB.
    }

  // Sub can have at most one carry bit.  Thus we know that the output
  // is, at worst, one more bit than the inputs.
  Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
  if (Tmp == 1) break;
  return std::min(Tmp, Tmp2)-1;

case Instruction::Mul: {
  // The output of the Mul can be at most twice the valid bits in the inputs.
  unsigned SignBitsOp0 = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
  if (SignBitsOp0 == 1) break;
  unsigned SignBitsOp1 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
  if (SignBitsOp1 == 1) break;
  unsigned OutValidBits =
      (TyBits - SignBitsOp0 + 1) + (TyBits - SignBitsOp1 + 1);
  return OutValidBits > TyBits ? 1 : TyBits - OutValidBits + 1;
}

case Instruction::PHI: {
  const PHINode *PN = cast<PHINode>(U);
  unsigned NumIncomingValues = PN->getNumIncomingValues();
  // Don't analyze large in-degree PHIs.
  if (NumIncomingValues > 4) break;
  // Unreachable blocks may have zero-operand PHI nodes.
  if (NumIncomingValues == 0) break;

  // Take the minimum of all incoming values.  This can't infinitely loop
  // because of our depth threshold.
  Tmp = ComputeNumSignBits(PN->getIncomingValue(0), Depth + 1, Q);
  for (unsigned i = 1, e = NumIncomingValues; i != e; ++i) {
    if (Tmp == 1) return Tmp;
    Tmp = std::min(
        Tmp, ComputeNumSignBits(PN->getIncomingValue(i), Depth + 1, Q));
  }
  return Tmp;
}

case Instruction::Trunc:
  // FIXME: it's tricky to do anything useful for this, but it is an important
  // case for targets like X86.
  break;

case Instruction::ExtractElement:
  // Look through extract element. At the moment we keep this simple and skip
  // tracking the specific element. But at least we might find information
  // valid for all elements of the vector (for example if vector is sign
  // extended, shifted, etc).
  return ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);

case Instruction::ShuffleVector: {
  // TODO: This is copied almost directly from the SelectionDAG version of
  //       ComputeNumSignBits. It would be better if we could share common
  //       code. If not, make sure that changes are translated to the DAG.

  // Collect the minimum number of sign bits that are shared by every vector
  // element referenced by the shuffle.
  auto *Shuf = cast<ShuffleVectorInst>(U);
  int NumElts = Shuf->getOperand(0)->getType()->getVectorNumElements();
  int NumMaskElts = Shuf->getMask()->getType()->getVectorNumElements();
  APInt DemandedLHS(NumElts, 0), DemandedRHS(NumElts, 0);
  for (int i = 0; i != NumMaskElts; ++i) {
    int M = Shuf->getMaskValue(i);
    assert(M < NumElts * 2 && "Invalid shuffle mask constant")((M < NumElts * 2 && "Invalid shuffle mask constant"
) ? static_cast<void> (0) : __assert_fail ("M < NumElts * 2 && \"Invalid shuffle mask constant\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 2617, __PRETTY_FUNCTION__));
    // For undef elements, we don't know anything about the common state of
    // the shuffle result.
    if (M == -1)
      return 1;
    if (M < NumElts)
      DemandedLHS.setBit(M % NumElts);
    else
      DemandedRHS.setBit(M % NumElts);
  }
  Tmp = std::numeric_limits<unsigned>::max();
  if (!!DemandedLHS)
    Tmp = ComputeNumSignBits(Shuf->getOperand(0), Depth + 1, Q);
  if (!!DemandedRHS) {
    Tmp2 = ComputeNumSignBits(Shuf->getOperand(1), Depth + 1, Q);
    Tmp = std::min(Tmp, Tmp2);
  }
  // If we don't know anything, early out and try computeKnownBits fall-back.
  if (Tmp == 1)
    break;
  assert(Tmp <= V->getType()->getScalarSizeInBits() &&((Tmp <= V->getType()->getScalarSizeInBits() &&
 "Failed to determine minimum sign bits") ? static_cast<void
> (0) : __assert_fail ("Tmp <= V->getType()->getScalarSizeInBits() && \"Failed to determine minimum sign bits\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 2638, __PRETTY_FUNCTION__))
         "Failed to determine minimum sign bits")((Tmp <= V->getType()->getScalarSizeInBits() &&
 "Failed to determine minimum sign bits") ? static_cast<void
> (0) : __assert_fail ("Tmp <= V->getType()->getScalarSizeInBits() && \"Failed to determine minimum sign bits\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 2638, __PRETTY_FUNCTION__));
  return Tmp;
}
}

// Finally, if we can prove that the top bits of the result are 0's or 1's,
// use this information.

// If we can examine all elements of a vector constant successfully, we're
// done (we can't do any better than that). If not, keep trying.
if (unsigned VecSignBits = computeNumSignBitsVectorConstant(V, TyBits))
  return VecSignBits;

KnownBits Known(TyBits);
computeKnownBits(V, Known, Depth, Q);

// If we know that the sign bit is either zero or one, determine the number of
// identical bits in the top of the input value.
return std::max(FirstAnswer, Known.countMinSignBits());
2657}

2659/// This function computes the integer multiple of Base that equals V.
2660/// If successful, it returns true and returns the multiple in
2661/// Multiple. If unsuccessful, it returns false. It looks
2662/// through SExt instructions only if LookThroughSExt is true.
2663bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple,
                         bool LookThroughSExt, unsigned Depth) {
const unsigned MaxDepth = 6;

assert(V && "No Value?")((V && "No Value?") ? static_cast<void> (0) : __assert_fail
 ("V && \"No Value?\"", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 2667, __PRETTY_FUNCTION__));
assert(Depth <= MaxDepth && "Limit Search Depth")((Depth <= MaxDepth && "Limit Search Depth") ? static_cast
<void> (0) : __assert_fail ("Depth <= MaxDepth && \"Limit Search Depth\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 2668, __PRETTY_FUNCTION__));
assert(V->getType()->isIntegerTy() && "Not integer or pointer type!")((V->getType()->isIntegerTy() && "Not integer or pointer type!"
) ? static_cast<void> (0) : __assert_fail ("V->getType()->isIntegerTy() && \"Not integer or pointer type!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 2669, __PRETTY_FUNCTION__));

Type *T = V->getType();

ConstantInt *CI = dyn_cast<ConstantInt>(V);

if (Base == 0)
  return false;

if (Base == 1) {
  Multiple = V;
  return true;
}

ConstantExpr *CO = dyn_cast<ConstantExpr>(V);
Constant *BaseVal = ConstantInt::get(T, Base);
if (CO && CO == BaseVal) {
  // Multiple is 1.
  Multiple = ConstantInt::get(T, 1);
  return true;
}

if (CI && CI->getZExtValue() % Base == 0) {
  Multiple = ConstantInt::get(T, CI->getZExtValue() / Base);
  return true;
}

if (Depth == MaxDepth) return false;  // Limit search depth.

Operator *I = dyn_cast<Operator>(V);
if (!I) return false;

switch (I->getOpcode()) {
default: break;
case Instruction::SExt:
  if (!LookThroughSExt) return false;
  // otherwise fall through to ZExt
  LLVM_FALLTHROUGH[[gnu::fallthrough]];
case Instruction::ZExt:
  return ComputeMultiple(I->getOperand(0), Base, Multiple,
                         LookThroughSExt, Depth+1);
case Instruction::Shl:
case Instruction::Mul: {
  Value *Op0 = I->getOperand(0);
  Value *Op1 = I->getOperand(1);

  if (I->getOpcode() == Instruction::Shl) {
    ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1);
    if (!Op1CI) return false;
    // Turn Op0 << Op1 into Op0 * 2^Op1
    APInt Op1Int = Op1CI->getValue();
    uint64_t BitToSet = Op1Int.getLimitedValue(Op1Int.getBitWidth() - 1);
    APInt API(Op1Int.getBitWidth(), 0);
    API.setBit(BitToSet);
    Op1 = ConstantInt::get(V->getContext(), API);
  }

  Value *Mul0 = nullptr;
  if (ComputeMultiple(Op0, Base, Mul0, LookThroughSExt, Depth+1)) {
    if (Constant *Op1C = dyn_cast<Constant>(Op1))
      if (Constant *MulC = dyn_cast<Constant>(Mul0)) {
        if (Op1C->getType()->getPrimitiveSizeInBits() <
            MulC->getType()->getPrimitiveSizeInBits())
          Op1C = ConstantExpr::getZExt(Op1C, MulC->getType());
        if (Op1C->getType()->getPrimitiveSizeInBits() >
            MulC->getType()->getPrimitiveSizeInBits())
          MulC = ConstantExpr::getZExt(MulC, Op1C->getType());

        // V == Base * (Mul0 * Op1), so return (Mul0 * Op1)
        Multiple = ConstantExpr::getMul(MulC, Op1C);
        return true;
      }

    if (ConstantInt *Mul0CI = dyn_cast<ConstantInt>(Mul0))
      if (Mul0CI->getValue() == 1) {
        // V == Base * Op1, so return Op1
        Multiple = Op1;
        return true;
      }
  }

  Value *Mul1 = nullptr;
  if (ComputeMultiple(Op1, Base, Mul1, LookThroughSExt, Depth+1)) {
    if (Constant *Op0C = dyn_cast<Constant>(Op0))
      if (Constant *MulC = dyn_cast<Constant>(Mul1)) {
        if (Op0C->getType()->getPrimitiveSizeInBits() <
            MulC->getType()->getPrimitiveSizeInBits())
          Op0C = ConstantExpr::getZExt(Op0C, MulC->getType());
        if (Op0C->getType()->getPrimitiveSizeInBits() >
            MulC->getType()->getPrimitiveSizeInBits())
          MulC = ConstantExpr::getZExt(MulC, Op0C->getType());

        // V == Base * (Mul1 * Op0), so return (Mul1 * Op0)
        Multiple = ConstantExpr::getMul(MulC, Op0C);
        return true;
      }

    if (ConstantInt *Mul1CI = dyn_cast<ConstantInt>(Mul1))
      if (Mul1CI->getValue() == 1) {
        // V == Base * Op0, so return Op0
        Multiple = Op0;
        return true;
      }
  }
}
}

// We could not determine if V is a multiple of Base.
return false;
2778}

2780Intrinsic::ID llvm::getIntrinsicForCallSite(ImmutableCallSite ICS,
                                          const TargetLibraryInfo *TLI) {
const Function *F = ICS.getCalledFunction();
if (!F)
  return Intrinsic::not_intrinsic;

if (F->isIntrinsic())
  return F->getIntrinsicID();

if (!TLI)
  return Intrinsic::not_intrinsic;

LibFunc Func;
// We're going to make assumptions on the semantics of the functions, check
// that the target knows that it's available in this environment and it does
// not have local linkage.
if (!F || F->hasLocalLinkage() || !TLI->getLibFunc(*F, Func))
  return Intrinsic::not_intrinsic;

if (!ICS.onlyReadsMemory())
  return Intrinsic::not_intrinsic;

// Otherwise check if we have a call to a function that can be turned into a
// vector intrinsic.
switch (Func) {
default:
  break;
case LibFunc_sin:
case LibFunc_sinf:
case LibFunc_sinl:
  return Intrinsic::sin;
case LibFunc_cos:
case LibFunc_cosf:
case LibFunc_cosl:
  return Intrinsic::cos;
case LibFunc_exp:
case LibFunc_expf:
case LibFunc_expl:
  return Intrinsic::exp;
case LibFunc_exp2:
case LibFunc_exp2f:
case LibFunc_exp2l:
  return Intrinsic::exp2;
case LibFunc_log:
case LibFunc_logf:
case LibFunc_logl:
  return Intrinsic::log;
case LibFunc_log10:
case LibFunc_log10f:
case LibFunc_log10l:
  return Intrinsic::log10;
case LibFunc_log2:
case LibFunc_log2f:
case LibFunc_log2l:
  return Intrinsic::log2;
case LibFunc_fabs:
case LibFunc_fabsf:
case LibFunc_fabsl:
  return Intrinsic::fabs;
case LibFunc_fmin:
case LibFunc_fminf:
case LibFunc_fminl:
  return Intrinsic::minnum;
case LibFunc_fmax:
case LibFunc_fmaxf:
case LibFunc_fmaxl:
  return Intrinsic::maxnum;
case LibFunc_copysign:
case LibFunc_copysignf:
case LibFunc_copysignl:
  return Intrinsic::copysign;
case LibFunc_floor:
case LibFunc_floorf:
case LibFunc_floorl:
  return Intrinsic::floor;
case LibFunc_ceil:
case LibFunc_ceilf:
case LibFunc_ceill:
  return Intrinsic::ceil;
case LibFunc_trunc:
case LibFunc_truncf:
case LibFunc_truncl:
  return Intrinsic::trunc;
case LibFunc_rint:
case LibFunc_rintf:
case LibFunc_rintl:
  return Intrinsic::rint;
case LibFunc_nearbyint:
case LibFunc_nearbyintf:
case LibFunc_nearbyintl:
  return Intrinsic::nearbyint;
case LibFunc_round:
case LibFunc_roundf:
case LibFunc_roundl:
  return Intrinsic::round;
case LibFunc_pow:
case LibFunc_powf:
case LibFunc_powl:
  return Intrinsic::pow;
case LibFunc_sqrt:
case LibFunc_sqrtf:
case LibFunc_sqrtl:
  return Intrinsic::sqrt;
}

return Intrinsic::not_intrinsic;
2886}

2888/// Return true if we can prove that the specified FP value is never equal to
2889/// -0.0.
2890///
2891/// NOTE: this function will need to be revisited when we support non-default
2892/// rounding modes!
2893bool llvm::CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI,
                              unsigned Depth) {
if (auto *CFP = dyn_cast<ConstantFP>(V))
  return !CFP->getValueAPF().isNegZero();

// Limit search depth.
if (Depth == MaxDepth)
  return false;

auto *Op = dyn_cast<Operator>(V);
if (!Op)
  return false;

// Check if the nsz fast-math flag is set.
if (auto *FPO = dyn_cast<FPMathOperator>(Op))
  if (FPO->hasNoSignedZeros())
    return true;

// (fadd x, 0.0) is guaranteed to return +0.0, not -0.0.
if (match(Op, m_FAdd(m_Value(), m_PosZeroFP())))
  return true;

// sitofp and uitofp turn into +0.0 for zero.
if (isa<SIToFPInst>(Op) || isa<UIToFPInst>(Op))
  return true;

if (auto *Call = dyn_cast<CallInst>(Op)) {
  Intrinsic::ID IID = getIntrinsicForCallSite(Call, TLI);
  switch (IID) {
  default:
    break;
  // sqrt(-0.0) = -0.0, no other negative results are possible.
  case Intrinsic::sqrt:
  case Intrinsic::canonicalize:
    return CannotBeNegativeZero(Call->getArgOperand(0), TLI, Depth + 1);
  // fabs(x) != -0.0
  case Intrinsic::fabs:
    return true;
  }
}

return false;
2935}

2937/// If \p SignBitOnly is true, test for a known 0 sign bit rather than a
2938/// standard ordered compare. e.g. make -0.0 olt 0.0 be true because of the sign
2939/// bit despite comparing equal.
2940static bool cannotBeOrderedLessThanZeroImpl(const Value *V,
                                          const TargetLibraryInfo *TLI,
                                          bool SignBitOnly,
                                          unsigned Depth) {
// TODO: This function does not do the right thing when SignBitOnly is true
// and we're lowering to a hypothetical IEEE 754-compliant-but-evil platform
// which flips the sign bits of NaNs.  See
// https://llvm.org/bugs/show_bug.cgi?id=31702.

if (const ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
  return !CFP->getValueAPF().isNegative() ||
         (!SignBitOnly && CFP->getValueAPF().isZero());
}

// Handle vector of constants.
if (auto *CV = dyn_cast<Constant>(V)) {
  if (CV->getType()->isVectorTy()) {
    unsigned NumElts = CV->getType()->getVectorNumElements();
    for (unsigned i = 0; i != NumElts; ++i) {
      auto *CFP = dyn_cast_or_null<ConstantFP>(CV->getAggregateElement(i));
      if (!CFP)
        return false;
      if (CFP->getValueAPF().isNegative() &&
          (SignBitOnly || !CFP->getValueAPF().isZero()))
        return false;
    }

    // All non-negative ConstantFPs.
    return true;
  }
}

if (Depth == MaxDepth)
  return false; // Limit search depth.

const Operator *I = dyn_cast<Operator>(V);
if (!I)
  return false;

switch (I->getOpcode()) {
default:
  break;
// Unsigned integers are always nonnegative.
case Instruction::UIToFP:
  return true;
case Instruction::FMul:
  // x*x is always non-negative or a NaN.
  if (I->getOperand(0) == I->getOperand(1) &&
      (!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs()))
    return true;

  LLVM_FALLTHROUGH[[gnu::fallthrough]];
case Instruction::FAdd:
case Instruction::FDiv:
case Instruction::FRem:
  return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly,
                                         Depth + 1) &&
         cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly,
                                         Depth + 1);
case Instruction::Select:
  return cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly,
                                         Depth + 1) &&
         cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly,
                                         Depth + 1);
case Instruction::FPExt:
case Instruction::FPTrunc:
  // Widening/narrowing never change sign.
  return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly,
                                         Depth + 1);
case Instruction::ExtractElement:
  // Look through extract element. At the moment we keep this simple and skip
  // tracking the specific element. But at least we might find information
  // valid for all elements of the vector.
  return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly,
                                         Depth + 1);
case Instruction::Call:
  const auto *CI = cast<CallInst>(I);
  Intrinsic::ID IID = getIntrinsicForCallSite(CI, TLI);
  switch (IID) {
  default:
    break;
  case Intrinsic::maxnum:
    return (isKnownNeverNaN(I->getOperand(0), TLI) &&
            cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI,
                                            SignBitOnly, Depth + 1)) ||
          (isKnownNeverNaN(I->getOperand(1), TLI) &&
            cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI,
                                            SignBitOnly, Depth + 1));

  case Intrinsic::maximum:
    return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly,
                                           Depth + 1) ||
           cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly,
                                           Depth + 1);
  case Intrinsic::minnum:
  case Intrinsic::minimum:
    return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly,
                                           Depth + 1) &&
           cannotBeOrderedLessThanZeroImpl(I->getOperand(1), TLI, SignBitOnly,
                                           Depth + 1);
  case Intrinsic::exp:
  case Intrinsic::exp2:
  case Intrinsic::fabs:
    return true;

  case Intrinsic::sqrt:
    // sqrt(x) is always >= -0 or NaN.  Moreover, sqrt(x) == -0 iff x == -0.
    if (!SignBitOnly)
      return true;
    return CI->hasNoNaNs() && (CI->hasNoSignedZeros() ||
                               CannotBeNegativeZero(CI->getOperand(0), TLI));

  case Intrinsic::powi:
    if (ConstantInt *Exponent = dyn_cast<ConstantInt>(I->getOperand(1))) {
      // powi(x,n) is non-negative if n is even.
      if (Exponent->getBitWidth() <= 64 && Exponent->getSExtValue() % 2u == 0)
        return true;
    }
    // TODO: This is not correct.  Given that exp is an integer, here are the
    // ways that pow can return a negative value:
    //
    //   pow(x, exp)    --> negative if exp is odd and x is negative.
    //   pow(-0, exp)   --> -inf if exp is negative odd.
    //   pow(-0, exp)   --> -0 if exp is positive odd.
    //   pow(-inf, exp) --> -0 if exp is negative odd.
    //   pow(-inf, exp) --> -inf if exp is positive odd.
    //
    // Therefore, if !SignBitOnly, we can return true if x >= +0 or x is NaN,
    // but we must return false if x == -0.  Unfortunately we do not currently
    // have a way of expressing this constraint.  See details in
    // https://llvm.org/bugs/show_bug.cgi?id=31702.
    return cannotBeOrderedLessThanZeroImpl(I->getOperand(0), TLI, SignBitOnly,
                                           Depth + 1);

  case Intrinsic::fma:
  case Intrinsic::fmuladd:
    // x*x+y is non-negative if y is non-negative.
    return I->getOperand(0) == I->getOperand(1) &&
           (!SignBitOnly || cast<FPMathOperator>(I)->hasNoNaNs()) &&
           cannotBeOrderedLessThanZeroImpl(I->getOperand(2), TLI, SignBitOnly,
                                           Depth + 1);
  }
  break;
}
return false;
3085}

3087bool llvm::CannotBeOrderedLessThanZero(const Value *V,
                                     const TargetLibraryInfo *TLI) {
return cannotBeOrderedLessThanZeroImpl(V, TLI, false, 0);
3090}

3092bool llvm::SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI) {
return cannotBeOrderedLessThanZeroImpl(V, TLI, true, 0);
3094}

3096bool llvm::isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI,
                         unsigned Depth) {
assert(V->getType()->isFPOrFPVectorTy() && "Querying for NaN on non-FP type")((V->getType()->isFPOrFPVectorTy() && "Querying for NaN on non-FP type"
) ? static_cast<void> (0) : __assert_fail ("V->getType()->isFPOrFPVectorTy() && \"Querying for NaN on non-FP type\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3098, __PRETTY_FUNCTION__));

// If we're told that NaNs won't happen, assume they won't.
if (auto *FPMathOp = dyn_cast<FPMathOperator>(V))
  if (FPMathOp->hasNoNaNs())
    return true;

// Handle scalar constants.
if (auto *CFP = dyn_cast<ConstantFP>(V))
  return !CFP->isNaN();

if (Depth == MaxDepth)
  return false;

if (auto *Inst = dyn_cast<Instruction>(V)) {
  switch (Inst->getOpcode()) {
  case Instruction::FAdd:
  case Instruction::FMul:
  case Instruction::FSub:
  case Instruction::FDiv:
  case Instruction::FRem: {
    // TODO: Need isKnownNeverInfinity
    return false;
  }
  case Instruction::Select: {
    return isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) &&
           isKnownNeverNaN(Inst->getOperand(2), TLI, Depth + 1);
  }
  case Instruction::SIToFP:
  case Instruction::UIToFP:
    return true;
  case Instruction::FPTrunc:
  case Instruction::FPExt:
    return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1);
  default:
    break;
  }
}

if (const auto *II = dyn_cast<IntrinsicInst>(V)) {
  switch (II->getIntrinsicID()) {
  case Intrinsic::canonicalize:
  case Intrinsic::fabs:
  case Intrinsic::copysign:
  case Intrinsic::exp:
  case Intrinsic::exp2:
  case Intrinsic::floor:
  case Intrinsic::ceil:
  case Intrinsic::trunc:
  case Intrinsic::rint:
  case Intrinsic::nearbyint:
  case Intrinsic::round:
    return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1);
  case Intrinsic::sqrt:
    return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) &&
           CannotBeOrderedLessThanZero(II->getArgOperand(0), TLI);
  case Intrinsic::minnum:
  case Intrinsic::maxnum:
    // If either operand is not NaN, the result is not NaN.
    return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) ||
           isKnownNeverNaN(II->getArgOperand(1), TLI, Depth + 1);
  default:
    return false;
  }
}

// Bail out for constant expressions, but try to handle vector constants.
if (!V->getType()->isVectorTy() || !isa<Constant>(V))
  return false;

// For vectors, verify that each element is not NaN.
unsigned NumElts = V->getType()->getVectorNumElements();
for (unsigned i = 0; i != NumElts; ++i) {
  Constant *Elt = cast<Constant>(V)->getAggregateElement(i);
  if (!Elt)
    return false;
  if (isa<UndefValue>(Elt))
    continue;
  auto *CElt = dyn_cast<ConstantFP>(Elt);
  if (!CElt || CElt->isNaN())
    return false;
}
// All elements were confirmed not-NaN or undefined.
return true;
3182}

3184Value *llvm::isBytewiseValue(Value *V, const DataLayout &DL) {

// All byte-wide stores are splatable, even of arbitrary variables.
if (V->getType()->isIntegerTy(8))
  return V;

LLVMContext &Ctx = V->getContext();

// Undef don't care.
auto *UndefInt8 = UndefValue::get(Type::getInt8Ty(Ctx));
if (isa<UndefValue>(V))
  return UndefInt8;

const uint64_t Size = DL.getTypeStoreSize(V->getType());
if (!Size)
  return UndefInt8;

Constant *C = dyn_cast<Constant>(V);
if (!C) {
  // Conceptually, we could handle things like:
  //   %a = zext i8 %X to i16
  //   %b = shl i16 %a, 8
  //   %c = or i16 %a, %b
  // but until there is an example that actually needs this, it doesn't seem
  // worth worrying about.
  return nullptr;
}

// Handle 'null' ConstantArrayZero etc.
if (C->isNullValue())
  return Constant::getNullValue(Type::getInt8Ty(Ctx));

// Constant floating-point values can be handled as integer values if the
// corresponding integer value is "byteable".  An important case is 0.0.
if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
  Type *Ty = nullptr;
  if (CFP->getType()->isHalfTy())
    Ty = Type::getInt16Ty(Ctx);
  else if (CFP->getType()->isFloatTy())
    Ty = Type::getInt32Ty(Ctx);
  else if (CFP->getType()->isDoubleTy())
    Ty = Type::getInt64Ty(Ctx);
  // Don't handle long double formats, which have strange constraints.
  return Ty ? isBytewiseValue(ConstantExpr::getBitCast(CFP, Ty), DL)
            : nullptr;
}

// We can handle constant integers that are multiple of 8 bits.
if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
  if (CI->getBitWidth() % 8 == 0) {
    assert(CI->getBitWidth() > 8 && "8 bits should be handled above!")((CI->getBitWidth() > 8 && "8 bits should be handled above!"
) ? static_cast<void> (0) : __assert_fail ("CI->getBitWidth() > 8 && \"8 bits should be handled above!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3234, __PRETTY_FUNCTION__));
    if (!CI->getValue().isSplat(8))
      return nullptr;
    return ConstantInt::get(Ctx, CI->getValue().trunc(8));
  }
}

if (auto *CE = dyn_cast<ConstantExpr>(C)) {
  if (CE->getOpcode() == Instruction::IntToPtr) {
    auto PS = DL.getPointerSizeInBits(
        cast<PointerType>(CE->getType())->getAddressSpace());
    return isBytewiseValue(
        ConstantExpr::getIntegerCast(CE->getOperand(0),
                                     Type::getIntNTy(Ctx, PS), false),
        DL);
  }
}

auto Merge = [&](Value *LHS, Value *RHS) -> Value * {
  if (LHS == RHS)
    return LHS;
  if (!LHS || !RHS)
    return nullptr;
  if (LHS == UndefInt8)
    return RHS;
  if (RHS == UndefInt8)
    return LHS;
  return nullptr;
};

if (ConstantDataSequential *CA = dyn_cast<ConstantDataSequential>(C)) {
  Value *Val = UndefInt8;
  for (unsigned I = 0, E = CA->getNumElements(); I != E; ++I)
    if (!(Val = Merge(Val, isBytewiseValue(CA->getElementAsConstant(I), DL))))
      return nullptr;
  return Val;
}

if (isa<ConstantAggregate>(C)) {
  Value *Val = UndefInt8;
  for (unsigned I = 0, E = C->getNumOperands(); I != E; ++I)
    if (!(Val = Merge(Val, isBytewiseValue(C->getOperand(I), DL))))
      return nullptr;
  return Val;
}

// Don't try to handle the handful of other constants.
return nullptr;
3282}

3284// This is the recursive version of BuildSubAggregate. It takes a few different
3285// arguments. Idxs is the index within the nested struct From that we are
3286// looking at now (which is of type IndexedType). IdxSkip is the number of
3287// indices from Idxs that should be left out when inserting into the resulting
3288// struct. To is the result struct built so far, new insertvalue instructions
3289// build on that.
3290static Value *BuildSubAggregate(Value *From, Value* To, Type *IndexedType,
                              SmallVectorImpl<unsigned> &Idxs,
                              unsigned IdxSkip,
                              Instruction *InsertBefore) {
StructType *STy = dyn_cast<StructType>(IndexedType);
if (STy) {
  // Save the original To argument so we can modify it
  Value *OrigTo = To;
  // General case, the type indexed by Idxs is a struct
  for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
    // Process each struct element recursively
    Idxs.push_back(i);
    Value *PrevTo = To;
    To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip,
                           InsertBefore);
    Idxs.pop_back();
    if (!To) {
      // Couldn't find any inserted value for this index? Cleanup
      while (PrevTo != OrigTo) {
        InsertValueInst* Del = cast<InsertValueInst>(PrevTo);
        PrevTo = Del->getAggregateOperand();
        Del->eraseFromParent();
      }
      // Stop processing elements
      break;
    }
  }
  // If we successfully found a value for each of our subaggregates
  if (To)
    return To;
}
// Base case, the type indexed by SourceIdxs is not a struct, or not all of
// the struct's elements had a value that was inserted directly. In the latter
// case, perhaps we can't determine each of the subelements individually, but
// we might be able to find the complete struct somewhere.

// Find the value that is at that particular spot
Value *V = FindInsertedValue(From, Idxs);

if (!V)
  return nullptr;

// Insert the value in the new (sub) aggregate
return InsertValueInst::Create(To, V, makeArrayRef(Idxs).slice(IdxSkip),
                               "tmp", InsertBefore);
3335}

3337// This helper takes a nested struct and extracts a part of it (which is again a
3338// struct) into a new value. For example, given the struct:
3339// { a, { b, { c, d }, e } }
3340// and the indices "1, 1" this returns
3341// { c, d }.
3342//
3343// It does this by inserting an insertvalue for each element in the resulting
3344// struct, as opposed to just inserting a single struct. This will only work if
3345// each of the elements of the substruct are known (ie, inserted into From by an
3346// insertvalue instruction somewhere).
3347//
3348// All inserted insertvalue instructions are inserted before InsertBefore
3349static Value *BuildSubAggregate(Value *From, ArrayRef<unsigned> idx_range,
                              Instruction *InsertBefore) {
assert(InsertBefore && "Must have someplace to insert!")((InsertBefore && "Must have someplace to insert!") ?
 static_cast<void> (0) : __assert_fail ("InsertBefore && \"Must have someplace to insert!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3351, __PRETTY_FUNCTION__));
Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(),
                                                           idx_range);
Value *To = UndefValue::get(IndexedType);
SmallVector<unsigned, 10> Idxs(idx_range.begin(), idx_range.end());
unsigned IdxSkip = Idxs.size();

return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore);
3359}

3361/// Given an aggregate and a sequence of indices, see if the scalar value
3362/// indexed is already around as a register, for example if it was inserted
3363/// directly into the aggregate.
3364///
3365/// If InsertBefore is not null, this function will duplicate (modified)
3366/// insertvalues when a part of a nested struct is extracted.
3367Value *llvm::FindInsertedValue(Value *V, ArrayRef<unsigned> idx_range,
                             Instruction *InsertBefore) {
// Nothing to index? Just return V then (this is useful at the end of our
// recursion).
if (idx_range.empty())
  return V;
// We have indices, so V should have an indexable type.
assert((V->getType()->isStructTy() || V->getType()->isArrayTy()) &&(((V->getType()->isStructTy() || V->getType()->isArrayTy
()) && "Not looking at a struct or array?") ? static_cast
<void> (0) : __assert_fail ("(V->getType()->isStructTy() || V->getType()->isArrayTy()) && \"Not looking at a struct or array?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3375, __PRETTY_FUNCTION__))
       "Not looking at a struct or array?")(((V->getType()->isStructTy() || V->getType()->isArrayTy
()) && "Not looking at a struct or array?") ? static_cast
<void> (0) : __assert_fail ("(V->getType()->isStructTy() || V->getType()->isArrayTy()) && \"Not looking at a struct or array?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3375, __PRETTY_FUNCTION__));
assert(ExtractValueInst::getIndexedType(V->getType(), idx_range) &&((ExtractValueInst::getIndexedType(V->getType(), idx_range
) && "Invalid indices for type?") ? static_cast<void
> (0) : __assert_fail ("ExtractValueInst::getIndexedType(V->getType(), idx_range) && \"Invalid indices for type?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3377, __PRETTY_FUNCTION__))
       "Invalid indices for type?")((ExtractValueInst::getIndexedType(V->getType(), idx_range
) && "Invalid indices for type?") ? static_cast<void
> (0) : __assert_fail ("ExtractValueInst::getIndexedType(V->getType(), idx_range) && \"Invalid indices for type?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3377, __PRETTY_FUNCTION__));

if (Constant *C = dyn_cast<Constant>(V)) {
  C = C->getAggregateElement(idx_range[0]);
  if (!C) return nullptr;
  return FindInsertedValue(C, idx_range.slice(1), InsertBefore);
}

if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) {
  // Loop the indices for the insertvalue instruction in parallel with the
  // requested indices
  const unsigned *req_idx = idx_range.begin();
  for (const unsigned *i = I->idx_begin(), *e = I->idx_end();
       i != e; ++i, ++req_idx) {
    if (req_idx == idx_range.end()) {
      // We can't handle this without inserting insertvalues
      if (!InsertBefore)
        return nullptr;

      // The requested index identifies a part of a nested aggregate. Handle
      // this specially. For example,
      // %A = insertvalue { i32, {i32, i32 } } undef, i32 10, 1, 0
      // %B = insertvalue { i32, {i32, i32 } } %A, i32 11, 1, 1
      // %C = extractvalue {i32, { i32, i32 } } %B, 1
      // This can be changed into
      // %A = insertvalue {i32, i32 } undef, i32 10, 0
      // %C = insertvalue {i32, i32 } %A, i32 11, 1
      // which allows the unused 0,0 element from the nested struct to be
      // removed.
      return BuildSubAggregate(V, makeArrayRef(idx_range.begin(), req_idx),
                               InsertBefore);
    }

    // This insert value inserts something else than what we are looking for.
    // See if the (aggregate) value inserted into has the value we are
    // looking for, then.
    if (*req_idx != *i)
      return FindInsertedValue(I->getAggregateOperand(), idx_range,
                               InsertBefore);
  }
  // If we end up here, the indices of the insertvalue match with those
  // requested (though possibly only partially). Now we recursively look at
  // the inserted value, passing any remaining indices.
  return FindInsertedValue(I->getInsertedValueOperand(),
                           makeArrayRef(req_idx, idx_range.end()),
                           InsertBefore);
}

if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) {
  // If we're extracting a value from an aggregate that was extracted from
  // something else, we can extract from that something else directly instead.
  // However, we will need to chain I's indices with the requested indices.

  // Calculate the number of indices required
  unsigned size = I->getNumIndices() + idx_range.size();
  // Allocate some space to put the new indices in
  SmallVector<unsigned, 5> Idxs;
  Idxs.reserve(size);
  // Add indices from the extract value instruction
  Idxs.append(I->idx_begin(), I->idx_end());

  // Add requested indices
  Idxs.append(idx_range.begin(), idx_range.end());

  assert(Idxs.size() == size((Idxs.size() == size && "Number of indices added not correct?"
) ? static_cast<void> (0) : __assert_fail ("Idxs.size() == size && \"Number of indices added not correct?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3442, __PRETTY_FUNCTION__))
         && "Number of indices added not correct?")((Idxs.size() == size && "Number of indices added not correct?"
) ? static_cast<void> (0) : __assert_fail ("Idxs.size() == size && \"Number of indices added not correct?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3442, __PRETTY_FUNCTION__));

  return FindInsertedValue(I->getAggregateOperand(), Idxs, InsertBefore);
}
// Otherwise, we don't know (such as, extracting from a function return value
// or load instruction)
return nullptr;
3449}

3451bool llvm::isGEPBasedOnPointerToString(const GEPOperator *GEP,
                                     unsigned CharSize) {
// Make sure the GEP has exactly three arguments.
if (GEP->getNumOperands() != 3)
  return false;

// Make sure the index-ee is a pointer to array of \p CharSize integers.
// CharSize.
ArrayType *AT = dyn_cast<ArrayType>(GEP->getSourceElementType());
if (!AT || !AT->getElementType()->isIntegerTy(CharSize))
  return false;

// Check to make sure that the first operand of the GEP is an integer and
// has value 0 so that we are sure we're indexing into the initializer.
const ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1));
if (!FirstIdx || !FirstIdx->isZero())
  return false;

return true;
3470}

3472bool llvm::getConstantDataArrayInfo(const Value *V,
                                  ConstantDataArraySlice &Slice,
                                  unsigned ElementSize, uint64_t Offset) {
assert(V)((V) ? static_cast<void> (0) : __assert_fail ("V", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3475, __PRETTY_FUNCTION__));

// Look through bitcast instructions and geps.
V = V->stripPointerCasts();

// If the value is a GEP instruction or constant expression, treat it as an
// offset.
if (const GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
  // The GEP operator should be based on a pointer to string constant, and is
  // indexing into the string constant.
  if (!isGEPBasedOnPointerToString(GEP, ElementSize))
    return false;

  // If the second index isn't a ConstantInt, then this is a variable index
  // into the array.  If this occurs, we can't say anything meaningful about
  // the string.
  uint64_t StartIdx = 0;
  if (const ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
    StartIdx = CI->getZExtValue();
  else
    return false;
  return getConstantDataArrayInfo(GEP->getOperand(0), Slice, ElementSize,
                                  StartIdx + Offset);
}

// The GEP instruction, constant or instruction, must reference a global
// variable that is a constant and is initialized. The referenced constant
// initializer is the array that we'll use for optimization.
const GlobalVariable *GV = dyn_cast<GlobalVariable>(V);
if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer())
  return false;

const ConstantDataArray *Array;
ArrayType *ArrayTy;
if (GV->getInitializer()->isNullValue()) {
  Type *GVTy = GV->getValueType();
  if ( (ArrayTy = dyn_cast<ArrayType>(GVTy)) ) {
    // A zeroinitializer for the array; there is no ConstantDataArray.
    Array = nullptr;
  } else {
    const DataLayout &DL = GV->getParent()->getDataLayout();
    uint64_t SizeInBytes = DL.getTypeStoreSize(GVTy);
    uint64_t Length = SizeInBytes / (ElementSize / 8);
    if (Length <= Offset)
      return false;

    Slice.Array = nullptr;
    Slice.Offset = 0;
    Slice.Length = Length - Offset;
    return true;
  }
} else {
  // This must be a ConstantDataArray.
  Array = dyn_cast<ConstantDataArray>(GV->getInitializer());
  if (!Array)
    return false;
  ArrayTy = Array->getType();
}
if (!ArrayTy->getElementType()->isIntegerTy(ElementSize))
  return false;

uint64_t NumElts = ArrayTy->getArrayNumElements();
if (Offset > NumElts)
  return false;

Slice.Array = Array;
Slice.Offset = Offset;
Slice.Length = NumElts - Offset;
return true;
3544}

3546/// This function computes the length of a null-terminated C string pointed to
3547/// by V. If successful, it returns true and returns the string in Str.
3548/// If unsuccessful, it returns false.
3549bool llvm::getConstantStringInfo(const Value *V, StringRef &Str,
                               uint64_t Offset, bool TrimAtNul) {
ConstantDataArraySlice Slice;
if (!getConstantDataArrayInfo(V, Slice, 8, Offset))
  return false;

if (Slice.Array == nullptr) {
  if (TrimAtNul) {
    Str = StringRef();
    return true;
  }
  if (Slice.Length == 1) {
    Str = StringRef("", 1);
    return true;
  }
  // We cannot instantiate a StringRef as we do not have an appropriate string
  // of 0s at hand.
  return false;
}

// Start out with the entire array in the StringRef.
Str = Slice.Array->getAsString();
// Skip over 'offset' bytes.
Str = Str.substr(Slice.Offset);

if (TrimAtNul) {
  // Trim off the \0 and anything after it.  If the array is not nul
  // terminated, we just return the whole end of string.  The client may know
  // some other way that the string is length-bound.
  Str = Str.substr(0, Str.find('\0'));
}
return true;
3581}

3583// These next two are very similar to the above, but also look through PHI
3584// nodes.
3585// TODO: See if we can integrate these two together.

3587/// If we can compute the length of the string pointed to by
3588/// the specified pointer, return 'len+1'.  If we can't, return 0.
3589static uint64_t GetStringLengthH(const Value *V,
                               SmallPtrSetImpl<const PHINode*> &PHIs,
                               unsigned CharSize) {
// Look through noop bitcast instructions.
V = V->stripPointerCasts();

// If this is a PHI node, there are two cases: either we have already seen it
// or we haven't.
if (const PHINode *PN = dyn_cast<PHINode>(V)) {
  if (!PHIs.insert(PN).second)
    return ~0ULL;  // already in the set.

  // If it was new, see if all the input strings are the same length.
  uint64_t LenSoFar = ~0ULL;
  for (Value *IncValue : PN->incoming_values()) {
    uint64_t Len = GetStringLengthH(IncValue, PHIs, CharSize);
    if (Len == 0) return 0; // Unknown length -> unknown.

    if (Len == ~0ULL) continue;

    if (Len != LenSoFar && LenSoFar != ~0ULL)
      return 0;    // Disagree -> unknown.
    LenSoFar = Len;
  }

  // Success, all agree.
  return LenSoFar;
}

// strlen(select(c,x,y)) -> strlen(x) ^ strlen(y)
if (const SelectInst *SI = dyn_cast<SelectInst>(V)) {
  uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs, CharSize);
  if (Len1 == 0) return 0;
  uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs, CharSize);
  if (Len2 == 0) return 0;
  if (Len1 == ~0ULL) return Len2;
  if (Len2 == ~0ULL) return Len1;
  if (Len1 != Len2) return 0;
  return Len1;
}

// Otherwise, see if we can read the string.
ConstantDataArraySlice Slice;
if (!getConstantDataArrayInfo(V, Slice, CharSize))
  return 0;

if (Slice.Array == nullptr)
  return 1;

// Search for nul characters
unsigned NullIndex = 0;
for (unsigned E = Slice.Length; NullIndex < E; ++NullIndex) {
  if (Slice.Array->getElementAsInteger(Slice.Offset + NullIndex) == 0)
    break;
}

return NullIndex + 1;
3646}

3648/// If we can compute the length of the string pointed to by
3649/// the specified pointer, return 'len+1'.  If we can't, return 0.
3650uint64_t llvm::GetStringLength(const Value *V, unsigned CharSize) {
if (!V->getType()->isPointerTy())
  return 0;

SmallPtrSet<const PHINode*, 32> PHIs;
uint64_t Len = GetStringLengthH(V, PHIs, CharSize);
// If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return
// an empty string as a length.
return Len == ~0ULL ? 1 : Len;
3659}

3661const Value *
3662llvm::getArgumentAliasingToReturnedPointer(const CallBase *Call,
                                         bool MustPreserveNullness) {
assert(Call &&((Call && "getArgumentAliasingToReturnedPointer only works on nonnull calls"
) ? static_cast<void> (0) : __assert_fail ("Call && \"getArgumentAliasingToReturnedPointer only works on nonnull calls\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3665, __PRETTY_FUNCTION__))
       "getArgumentAliasingToReturnedPointer only works on nonnull calls")((Call && "getArgumentAliasingToReturnedPointer only works on nonnull calls"
) ? static_cast<void> (0) : __assert_fail ("Call && \"getArgumentAliasingToReturnedPointer only works on nonnull calls\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3665, __PRETTY_FUNCTION__));
if (const Value *RV = Call->getReturnedArgOperand())
  return RV;
// This can be used only as a aliasing property.
if (isIntrinsicReturningPointerAliasingArgumentWithoutCapturing(
        Call, MustPreserveNullness))
  return Call->getArgOperand(0);
return nullptr;
3673}

3675bool llvm::isIntrinsicReturningPointerAliasingArgumentWithoutCapturing(
  const CallBase *Call, bool MustPreserveNullness) {
return Call->getIntrinsicID() == Intrinsic::launder_invariant_group ||
       Call->getIntrinsicID() == Intrinsic::strip_invariant_group ||
       Call->getIntrinsicID() == Intrinsic::aarch64_irg ||
       Call->getIntrinsicID() == Intrinsic::aarch64_tagp ||
       (!MustPreserveNullness &&
        Call->getIntrinsicID() == Intrinsic::ptrmask);
3683}

3685/// \p PN defines a loop-variant pointer to an object.  Check if the
3686/// previous iteration of the loop was referring to the same object as \p PN.
3687static bool isSameUnderlyingObjectInLoop(const PHINode *PN,
                                       const LoopInfo *LI) {
// Find the loop-defined value.
Loop *L = LI->getLoopFor(PN->getParent());
if (PN->getNumIncomingValues() != 2)
  return true;

// Find the value from previous iteration.
auto *PrevValue = dyn_cast<Instruction>(PN->getIncomingValue(0));
if (!PrevValue || LI->getLoopFor(PrevValue->getParent()) != L)
  PrevValue = dyn_cast<Instruction>(PN->getIncomingValue(1));
if (!PrevValue || LI->getLoopFor(PrevValue->getParent()) != L)
  return true;

// If a new pointer is loaded in the loop, the pointer references a different
// object in every iteration.  E.g.:
//    for (i)
//       int *p = a[i];
//       ...
if (auto *Load = dyn_cast<LoadInst>(PrevValue))
  if (!L->isLoopInvariant(Load->getPointerOperand()))
    return false;
return true;
3710}

3712Value *llvm::GetUnderlyingObject(Value *V, const DataLayout &DL,
                               unsigned MaxLookup) {
if (!V->getType()->isPointerTy())
  return V;
for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) {
  if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
    V = GEP->getPointerOperand();
  } else if (Operator::getOpcode(V) == Instruction::BitCast ||
             Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
    V = cast<Operator>(V)->getOperand(0);
  } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
    if (GA->isInterposable())
      return V;
    V = GA->getAliasee();
  } else if (isa<AllocaInst>(V)) {
    // An alloca can't be further simplified.
    return V;
  } else {
    if (auto *Call = dyn_cast<CallBase>(V)) {
      // CaptureTracking can know about special capturing properties of some
      // intrinsics like launder.invariant.group, that can't be expressed with
      // the attributes, but have properties like returning aliasing pointer.
      // Because some analysis may assume that nocaptured pointer is not
      // returned from some special intrinsic (because function would have to
      // be marked with returns attribute), it is crucial to use this function
      // because it should be in sync with CaptureTracking. Not using it may
      // cause weird miscompilations where 2 aliasing pointers are assumed to
      // noalias.
      if (auto *RP = getArgumentAliasingToReturnedPointer(Call, false)) {
        V = RP;
        continue;
      }
    }

    // See if InstructionSimplify knows any relevant tricks.
    if (Instruction *I = dyn_cast<Instruction>(V))
      // TODO: Acquire a DominatorTree and AssumptionCache and use them.
      if (Value *Simplified = SimplifyInstruction(I, {DL, I})) {
        V = Simplified;
        continue;
      }

    return V;
  }
  assert(V->getType()->isPointerTy() && "Unexpected operand type!")((V->getType()->isPointerTy() && "Unexpected operand type!"
) ? static_cast<void> (0) : __assert_fail ("V->getType()->isPointerTy() && \"Unexpected operand type!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3756, __PRETTY_FUNCTION__));
}
return V;
3759}

3761void llvm::GetUnderlyingObjects(const Value *V,
                              SmallVectorImpl<const Value *> &Objects,
                              const DataLayout &DL, LoopInfo *LI,
                              unsigned MaxLookup) {
SmallPtrSet<const Value *, 4> Visited;
SmallVector<const Value *, 4> Worklist;
Worklist.push_back(V);
do {
  const Value *P = Worklist.pop_back_val();
  P = GetUnderlyingObject(P, DL, MaxLookup);

  if (!Visited.insert(P).second)
    continue;

  if (auto *SI = dyn_cast<SelectInst>(P)) {
    Worklist.push_back(SI->getTrueValue());
    Worklist.push_back(SI->getFalseValue());
    continue;
  }

  if (auto *PN = dyn_cast<PHINode>(P)) {
    // If this PHI changes the underlying object in every iteration of the
    // loop, don't look through it.  Consider:
    //   int **A;
    //   for (i) {
    //     Prev = Curr;     // Prev = PHI (Prev_0, Curr)
    //     Curr = A[i];
    //     *Prev, *Curr;
    //
    // Prev is tracking Curr one iteration behind so they refer to different
    // underlying objects.
    if (!LI || !LI->isLoopHeader(PN->getParent()) ||
        isSameUnderlyingObjectInLoop(PN, LI))
      for (Value *IncValue : PN->incoming_values())
        Worklist.push_back(IncValue);
    continue;
  }

  Objects.push_back(P);
} while (!Worklist.empty());
3801}

3803/// This is the function that does the work of looking through basic
3804/// ptrtoint+arithmetic+inttoptr sequences.
3805static const Value *getUnderlyingObjectFromInt(const Value *V) {
do {
  if (const Operator *U = dyn_cast<Operator>(V)) {
    // If we find a ptrtoint, we can transfer control back to the
    // regular getUnderlyingObjectFromInt.
    if (U->getOpcode() == Instruction::PtrToInt)
      return U->getOperand(0);
    // If we find an add of a constant, a multiplied value, or a phi, it's
    // likely that the other operand will lead us to the base
    // object. We don't have to worry about the case where the
    // object address is somehow being computed by the multiply,
    // because our callers only care when the result is an
    // identifiable object.
    if (U->getOpcode() != Instruction::Add ||
        (!isa<ConstantInt>(U->getOperand(1)) &&
         Operator::getOpcode(U->getOperand(1)) != Instruction::Mul &&
         !isa<PHINode>(U->getOperand(1))))
      return V;
    V = U->getOperand(0);
  } else {
    return V;
  }
  assert(V->getType()->isIntegerTy() && "Unexpected operand type!")((V->getType()->isIntegerTy() && "Unexpected operand type!"
) ? static_cast<void> (0) : __assert_fail ("V->getType()->isIntegerTy() && \"Unexpected operand type!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3827, __PRETTY_FUNCTION__));
} while (true);
3829}

3831/// This is a wrapper around GetUnderlyingObjects and adds support for basic
3832/// ptrtoint+arithmetic+inttoptr sequences.
3833/// It returns false if unidentified object is found in GetUnderlyingObjects.
3834bool llvm::getUnderlyingObjectsForCodeGen(const Value *V,
                        SmallVectorImpl<Value *> &Objects,
                        const DataLayout &DL) {
SmallPtrSet<const Value *, 16> Visited;
SmallVector<const Value *, 4> Working(1, V);
do {
  V = Working.pop_back_val();

  SmallVector<const Value *, 4> Objs;
  GetUnderlyingObjects(V, Objs, DL);

  for (const Value *V : Objs) {
    if (!Visited.insert(V).second)
      continue;
    if (Operator::getOpcode(V) == Instruction::IntToPtr) {
      const Value *O =
        getUnderlyingObjectFromInt(cast<User>(V)->getOperand(0));
      if (O->getType()->isPointerTy()) {
        Working.push_back(O);
        continue;
      }
    }
    // If GetUnderlyingObjects fails to find an identifiable object,
    // getUnderlyingObjectsForCodeGen also fails for safety.
    if (!isIdentifiedObject(V)) {
      Objects.clear();
      return false;
    }
    Objects.push_back(const_cast<Value *>(V));
  }
} while (!Working.empty());
return true;
3866}

3868/// Return true if the only users of this pointer are lifetime markers.
3869bool llvm::onlyUsedByLifetimeMarkers(const Value *V) {
for (const User *U : V->users()) {
  const IntrinsicInst *II = dyn_cast<IntrinsicInst>(U);
  if (!II) return false;

  if (!II->isLifetimeStartOrEnd())
    return false;
}
return true;
3878}

3880bool llvm::mustSuppressSpeculation(const LoadInst &LI) {
if (!LI.isUnordered())
  return true;
const Function &F = *LI.getFunction();
// Speculative load may create a race that did not exist in the source.
return F.hasFnAttribute(Attribute::SanitizeThread) ||
  // Speculative load may load data from dirty regions.
  F.hasFnAttribute(Attribute::SanitizeAddress) ||
  F.hasFnAttribute(Attribute::SanitizeHWAddress);
3889}


3892bool llvm::isSafeToSpeculativelyExecute(const Value *V,
                                      const Instruction *CtxI,
                                      const DominatorTree *DT) {
const Operator *Inst = dyn_cast<Operator>(V);
if (!Inst)
  return false;

for (unsigned i = 0, e = Inst->getNumOperands(); i != e; ++i)
  if (Constant *C = dyn_cast<Constant>(Inst->getOperand(i)))
    if (C->canTrap())
      return false;

switch (Inst->getOpcode()) {
default:
  return true;
case Instruction::UDiv:
case Instruction::URem: {
  // x / y is undefined if y == 0.
  const APInt *V;
  if (match(Inst->getOperand(1), m_APInt(V)))
    return *V != 0;
  return false;
}
case Instruction::SDiv:
case Instruction::SRem: {
  // x / y is undefined if y == 0 or x == INT_MIN and y == -1
  const APInt *Numerator, *Denominator;
  if (!match(Inst->getOperand(1), m_APInt(Denominator)))
    return false;
  // We cannot hoist this division if the denominator is 0.
  if (*Denominator == 0)
    return false;
  // It's safe to hoist if the denominator is not 0 or -1.
  if (*Denominator != -1)
    return true;
  // At this point we know that the denominator is -1.  It is safe to hoist as
  // long we know that the numerator is not INT_MIN.
  if (match(Inst->getOperand(0), m_APInt(Numerator)))
    return !Numerator->isMinSignedValue();
  // The numerator *might* be MinSignedValue.
  return false;
}
case Instruction::Load: {
  const LoadInst *LI = cast<LoadInst>(Inst);
  if (mustSuppressSpeculation(*LI))
    return false;
  const DataLayout &DL = LI->getModule()->getDataLayout();
  return isDereferenceableAndAlignedPointer(LI->getPointerOperand(),
                                            LI->getType(), LI->getAlignment(),
                                            DL, CtxI, DT);
}
case Instruction::Call: {
  auto *CI = cast<const CallInst>(Inst);
  const Function *Callee = CI->getCalledFunction();

  // The called function could have undefined behavior or side-effects, even
  // if marked readnone nounwind.
  return Callee && Callee->isSpeculatable();
}
case Instruction::VAArg:
case Instruction::Alloca:
case Instruction::Invoke:
case Instruction::CallBr:
case Instruction::PHI:
case Instruction::Store:
case Instruction::Ret:
case Instruction::Br:
case Instruction::IndirectBr:
case Instruction::Switch:
case Instruction::Unreachable:
case Instruction::Fence:
case Instruction::AtomicRMW:
case Instruction::AtomicCmpXchg:
case Instruction::LandingPad:
case Instruction::Resume:
case Instruction::CatchSwitch:
case Instruction::CatchPad:
case Instruction::CatchRet:
case Instruction::CleanupPad:
case Instruction::CleanupRet:
  return false; // Misc instructions which have effects
}
3974}

3976bool llvm::mayBeMemoryDependent(const Instruction &I) {
return I.mayReadOrWriteMemory() || !isSafeToSpeculativelyExecute(&I);
3978}

3980/// Convert ConstantRange OverflowResult into ValueTracking OverflowResult.
3981static OverflowResult mapOverflowResult(ConstantRange::OverflowResult OR) {
switch (OR) {
  case ConstantRange::OverflowResult::MayOverflow:
    return OverflowResult::MayOverflow;
  case ConstantRange::OverflowResult::AlwaysOverflowsLow:
    return OverflowResult::AlwaysOverflowsLow;
  case ConstantRange::OverflowResult::AlwaysOverflowsHigh:
    return OverflowResult::AlwaysOverflowsHigh;
  case ConstantRange::OverflowResult::NeverOverflows:
    return OverflowResult::NeverOverflows;
}
llvm_unreachable("Unknown OverflowResult")::llvm::llvm_unreachable_internal("Unknown OverflowResult", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 3992);
3993}

3995/// Combine constant ranges from computeConstantRange() and computeKnownBits().
3996static ConstantRange computeConstantRangeIncludingKnownBits(
  const Value *V, bool ForSigned, const DataLayout &DL, unsigned Depth,
  AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT,
  OptimizationRemarkEmitter *ORE = nullptr, bool UseInstrInfo = true) {
KnownBits Known = computeKnownBits(
    V, DL, Depth, AC, CxtI, DT, ORE, UseInstrInfo);
ConstantRange CR1 = ConstantRange::fromKnownBits(Known, ForSigned);
ConstantRange CR2 = computeConstantRange(V, UseInstrInfo);
ConstantRange::PreferredRangeType RangeType =
    ForSigned ? ConstantRange::Signed : ConstantRange::Unsigned;
return CR1.intersectWith(CR2, RangeType);
4007}

4009OverflowResult llvm::computeOverflowForUnsignedMul(
  const Value *LHS, const Value *RHS, const DataLayout &DL,
  AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT,
  bool UseInstrInfo) {
KnownBits LHSKnown = computeKnownBits(LHS, DL, /*Depth=*/0, AC, CxtI, DT,
                                      nullptr, UseInstrInfo);
KnownBits RHSKnown = computeKnownBits(RHS, DL, /*Depth=*/0, AC, CxtI, DT,
                                      nullptr, UseInstrInfo);
ConstantRange LHSRange = ConstantRange::fromKnownBits(LHSKnown, false);
ConstantRange RHSRange = ConstantRange::fromKnownBits(RHSKnown, false);
return mapOverflowResult(LHSRange.unsignedMulMayOverflow(RHSRange));
4020}

4022OverflowResult
4023llvm::computeOverflowForSignedMul(const Value *LHS, const Value *RHS,
                                const DataLayout &DL, AssumptionCache *AC,
                                const Instruction *CxtI,
                                const DominatorTree *DT, bool UseInstrInfo) {
// Multiplying n * m significant bits yields a result of n + m significant
// bits. If the total number of significant bits does not exceed the
// result bit width (minus 1), there is no overflow.
// This means if we have enough leading sign bits in the operands
// we can guarantee that the result does not overflow.
// Ref: "Hacker's Delight" by Henry Warren
unsigned BitWidth = LHS->getType()->getScalarSizeInBits();

// Note that underestimating the number of sign bits gives a more
// conservative answer.
unsigned SignBits = ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) +
                    ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT);

// First handle the easy case: if we have enough sign bits there's
// definitely no overflow.
if (SignBits > BitWidth + 1)
  return OverflowResult::NeverOverflows;

// There are two ambiguous cases where there can be no overflow:
//   SignBits == BitWidth + 1    and
//   SignBits == BitWidth
// The second case is difficult to check, therefore we only handle the
// first case.
if (SignBits == BitWidth + 1) {
  // It overflows only when both arguments are negative and the true
  // product is exactly the minimum negative number.
  // E.g. mul i16 with 17 sign bits: 0xff00 * 0xff80 = 0x8000
  // For simplicity we just check if at least one side is not negative.
  KnownBits LHSKnown = computeKnownBits(LHS, DL, /*Depth=*/0, AC, CxtI, DT,
                                        nullptr, UseInstrInfo);
  KnownBits RHSKnown = computeKnownBits(RHS, DL, /*Depth=*/0, AC, CxtI, DT,
                                        nullptr, UseInstrInfo);
  if (LHSKnown.isNonNegative() || RHSKnown.isNonNegative())
    return OverflowResult::NeverOverflows;
}
return OverflowResult::MayOverflow;
4063}

4065OverflowResult llvm::computeOverflowForUnsignedAdd(
  const Value *LHS, const Value *RHS, const DataLayout &DL,
  AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT,
  bool UseInstrInfo) {
ConstantRange LHSRange = computeConstantRangeIncludingKnownBits(
    LHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT,
    nullptr, UseInstrInfo);
ConstantRange RHSRange = computeConstantRangeIncludingKnownBits(
    RHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT,
    nullptr, UseInstrInfo);
return mapOverflowResult(LHSRange.unsignedAddMayOverflow(RHSRange));
4076}

4078static OverflowResult computeOverflowForSignedAdd(const Value *LHS,
                                                const Value *RHS,
                                                const AddOperator *Add,
                                                const DataLayout &DL,
                                                AssumptionCache *AC,
                                                const Instruction *CxtI,
                                                const DominatorTree *DT) {
if (Add && Add->hasNoSignedWrap()) {
  return OverflowResult::NeverOverflows;
}

// If LHS and RHS each have at least two sign bits, the addition will look
// like
//
// XX..... +
// YY.....
//
// If the carry into the most significant position is 0, X and Y can't both
// be 1 and therefore the carry out of the addition is also 0.
//
// If the carry into the most significant position is 1, X and Y can't both
// be 0 and therefore the carry out of the addition is also 1.
//
// Since the carry into the most significant position is always equal to
// the carry out of the addition, there is no signed overflow.
if (ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) > 1 &&
    ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT) > 1)
  return OverflowResult::NeverOverflows;

ConstantRange LHSRange = computeConstantRangeIncludingKnownBits(
    LHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT);
ConstantRange RHSRange = computeConstantRangeIncludingKnownBits(
    RHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT);
OverflowResult OR =
    mapOverflowResult(LHSRange.signedAddMayOverflow(RHSRange));
if (OR != OverflowResult::MayOverflow)
  return OR;

// The remaining code needs Add to be available. Early returns if not so.
if (!Add)
  return OverflowResult::MayOverflow;

// If the sign of Add is the same as at least one of the operands, this add
// CANNOT overflow. If this can be determined from the known bits of the
// operands the above signedAddMayOverflow() check will have already done so.
// The only other way to improve on the known bits is from an assumption, so
// call computeKnownBitsFromAssume() directly.
bool LHSOrRHSKnownNonNegative =
    (LHSRange.isAllNonNegative() || RHSRange.isAllNonNegative());
bool LHSOrRHSKnownNegative =
    (LHSRange.isAllNegative() || RHSRange.isAllNegative());
if (LHSOrRHSKnownNonNegative || LHSOrRHSKnownNegative) {
  KnownBits AddKnown(LHSRange.getBitWidth());
  computeKnownBitsFromAssume(
      Add, AddKnown, /*Depth=*/0, Query(DL, AC, CxtI, DT, true));
  if ((AddKnown.isNonNegative() && LHSOrRHSKnownNonNegative) ||
      (AddKnown.isNegative() && LHSOrRHSKnownNegative))
    return OverflowResult::NeverOverflows;
}

return OverflowResult::MayOverflow;
4139}

4141OverflowResult llvm::computeOverflowForUnsignedSub(const Value *LHS,
                                                 const Value *RHS,
                                                 const DataLayout &DL,
                                                 AssumptionCache *AC,
                                                 const Instruction *CxtI,
                                                 const DominatorTree *DT) {
ConstantRange LHSRange = computeConstantRangeIncludingKnownBits(
    LHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT);
ConstantRange RHSRange = computeConstantRangeIncludingKnownBits(
    RHS, /*ForSigned=*/false, DL, /*Depth=*/0, AC, CxtI, DT);
return mapOverflowResult(LHSRange.unsignedSubMayOverflow(RHSRange));
4152}

4154OverflowResult llvm::computeOverflowForSignedSub(const Value *LHS,
                                               const Value *RHS,
                                               const DataLayout &DL,
                                               AssumptionCache *AC,
                                               const Instruction *CxtI,
                                               const DominatorTree *DT) {
// If LHS and RHS each have at least two sign bits, the subtraction
// cannot overflow.
if (ComputeNumSignBits(LHS, DL, 0, AC, CxtI, DT) > 1 &&
    ComputeNumSignBits(RHS, DL, 0, AC, CxtI, DT) > 1)
  return OverflowResult::NeverOverflows;

ConstantRange LHSRange = computeConstantRangeIncludingKnownBits(
    LHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT);
ConstantRange RHSRange = computeConstantRangeIncludingKnownBits(
    RHS, /*ForSigned=*/true, DL, /*Depth=*/0, AC, CxtI, DT);
return mapOverflowResult(LHSRange.signedSubMayOverflow(RHSRange));
4171}

4173bool llvm::isOverflowIntrinsicNoWrap(const WithOverflowInst *WO,
                                   const DominatorTree &DT) {
SmallVector<const BranchInst *, 2> GuardingBranches;
SmallVector<const ExtractValueInst *, 2> Results;

for (const User *U : WO->users()) {
  if (const auto *EVI = dyn_cast<ExtractValueInst>(U)) {
    assert(EVI->getNumIndices() == 1 && "Obvious from CI's type")((EVI->getNumIndices() == 1 && "Obvious from CI's type"
) ? static_cast<void> (0) : __assert_fail ("EVI->getNumIndices() == 1 && \"Obvious from CI's type\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 4180, __PRETTY_FUNCTION__));

    if (EVI->getIndices()[0] == 0)
      Results.push_back(EVI);
    else {
      assert(EVI->getIndices()[0] == 1 && "Obvious from CI's type")((EVI->getIndices()[0] == 1 && "Obvious from CI's type"
) ? static_cast<void> (0) : __assert_fail ("EVI->getIndices()[0] == 1 && \"Obvious from CI's type\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 4185, __PRETTY_FUNCTION__));

      for (const auto *U : EVI->users())
        if (const auto *B = dyn_cast<BranchInst>(U)) {
          assert(B->isConditional() && "How else is it using an i1?")((B->isConditional() && "How else is it using an i1?"
) ? static_cast<void> (0) : __assert_fail ("B->isConditional() && \"How else is it using an i1?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 4189, __PRETTY_FUNCTION__));
          GuardingBranches.push_back(B);
        }
    }
  } else {
    // We are using the aggregate directly in a way we don't want to analyze
    // here (storing it to a global, say).
    return false;
  }
}

auto AllUsesGuardedByBranch = [&](const BranchInst *BI) {
  BasicBlockEdge NoWrapEdge(BI->getParent(), BI->getSuccessor(1));
  if (!NoWrapEdge.isSingleEdge())
    return false;

  // Check if all users of the add are provably no-wrap.
  for (const auto *Result : Results) {
    // If the extractvalue itself is not executed on overflow, the we don't
    // need to check each use separately, since domination is transitive.
    if (DT.dominates(NoWrapEdge, Result->getParent()))
      continue;

    for (auto &RU : Result->uses())
      if (!DT.dominates(NoWrapEdge, RU))
        return false;
  }

  return true;
};

return llvm::any_of(GuardingBranches, AllUsesGuardedByBranch);
4221}


4224OverflowResult llvm::computeOverflowForSignedAdd(const AddOperator *Add,
                                               const DataLayout &DL,
                                               AssumptionCache *AC,
                                               const Instruction *CxtI,
                                               const DominatorTree *DT) {
return ::computeOverflowForSignedAdd(Add->getOperand(0), Add->getOperand(1),
                                     Add, DL, AC, CxtI, DT);
4231}

4233OverflowResult llvm::computeOverflowForSignedAdd(const Value *LHS,
                                               const Value *RHS,
                                               const DataLayout &DL,
                                               AssumptionCache *AC,
                                               const Instruction *CxtI,
                                               const DominatorTree *DT) {
return ::computeOverflowForSignedAdd(LHS, RHS, nullptr, DL, AC, CxtI, DT);
4240}

4242bool llvm::isGuaranteedToTransferExecutionToSuccessor(const Instruction *I) {
// Note: An atomic operation isn't guaranteed to return in a reasonable amount
// of time because it's possible for another thread to interfere with it for an
// arbitrary length of time, but programs aren't allowed to rely on that.

// If there is no successor, then execution can't transfer to it.
if (const auto *CRI = dyn_cast<CleanupReturnInst>(I))
  return !CRI->unwindsToCaller();
if (const auto *CatchSwitch = dyn_cast<CatchSwitchInst>(I))
  return !CatchSwitch->unwindsToCaller();
if (isa<ResumeInst>(I))
  return false;
if (isa<ReturnInst>(I))
  return false;
if (isa<UnreachableInst>(I))
  return false;

// Calls can throw, or contain an infinite loop, or kill the process.
if (auto CS = ImmutableCallSite(I)) {
  // Call sites that throw have implicit non-local control flow.
  if (!CS.doesNotThrow())
    return false;

  // A function which doens't throw and has "willreturn" attribute will
  // always return.
  if (CS.hasFnAttr(Attribute::WillReturn))
    return true;

  // Non-throwing call sites can loop infinitely, call exit/pthread_exit
  // etc. and thus not return.  However, LLVM already assumes that
  //
  //  - Thread exiting actions are modeled as writes to memory invisible to
  //    the program.
  //
  //  - Loops that don't have side effects (side effects are volatile/atomic
  //    stores and IO) always terminate (see http://llvm.org/PR965).
  //    Furthermore IO itself is also modeled as writes to memory invisible to
  //    the program.
  //
  // We rely on those assumptions here, and use the memory effects of the call
  // target as a proxy for checking that it always returns.

  // FIXME: This isn't aggressive enough; a call which only writes to a global
  // is guaranteed to return.
  return CS.onlyReadsMemory() || CS.onlyAccessesArgMemory();
}

// Other instructions return normally.
return true;
4291}

4293bool llvm::isGuaranteedToTransferExecutionToSuccessor(const BasicBlock *BB) {
// TODO: This is slightly conservative for invoke instruction since exiting
// via an exception *is* normal control for them.
for (auto I = BB->begin(), E = BB->end(); I != E; ++I)
  if (!isGuaranteedToTransferExecutionToSuccessor(&*I))
    return false;
return true;
4300}

4302bool llvm::isGuaranteedToExecuteForEveryIteration(const Instruction *I,
                                                const Loop *L) {
// The loop header is guaranteed to be executed for every iteration.
//
// FIXME: Relax this constraint to cover all basic blocks that are
// guaranteed to be executed at every iteration.
if (I->getParent() != L->getHeader()) return false;

for (const Instruction &LI : *L->getHeader()) {
  if (&LI == I) return true;
  if (!isGuaranteedToTransferExecutionToSuccessor(&LI)) return false;
}
llvm_unreachable("Instruction not contained in its own parent basic block.")::llvm::llvm_unreachable_internal("Instruction not contained in its own parent basic block."
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 4314);
4315}

4317bool llvm::propagatesFullPoison(const Instruction *I) {
// TODO: This should include all instructions apart from phis, selects and
// call-like instructions.
switch (I->getOpcode()) {
case Instruction::Add:
case Instruction::Sub:
case Instruction::Xor:
case Instruction::Trunc:
case Instruction::BitCast:
case Instruction::AddrSpaceCast:
case Instruction::Mul:
case Instruction::Shl:
case Instruction::GetElementPtr:
  // These operations all propagate poison unconditionally. Note that poison
  // is not any particular value, so xor or subtraction of poison with
  // itself still yields poison, not zero.
  return true;

case Instruction::AShr:
case Instruction::SExt:
  // For these operations, one bit of the input is replicated across
  // multiple output bits. A replicated poison bit is still poison.
  return true;

case Instruction::ICmp:
  // Comparing poison with any value yields poison.  This is why, for
  // instance, x s< (x +nsw 1) can be folded to true.
  return true;

default:
  return false;
}
4349}

4351const Value *llvm::getGuaranteedNonFullPoisonOp(const Instruction *I) {
switch (I->getOpcode()) {
  case Instruction::Store:
    return cast<StoreInst>(I)->getPointerOperand();

  case Instruction::Load:
    return cast<LoadInst>(I)->getPointerOperand();

  case Instruction::AtomicCmpXchg:
    return cast<AtomicCmpXchgInst>(I)->getPointerOperand();

  case Instruction::AtomicRMW:
    return cast<AtomicRMWInst>(I)->getPointerOperand();

  case Instruction::UDiv:
  case Instruction::SDiv:
  case Instruction::URem:
  case Instruction::SRem:
    return I->getOperand(1);

  default:
    // Note: It's really tempting to think that a conditional branch or
    // switch should be listed here, but that's incorrect.  It's not
    // branching off of poison which is UB, it is executing a side effecting
    // instruction which follows the branch.
    return nullptr;
}
4378}

4380bool llvm::mustTriggerUB(const Instruction *I,
                       const SmallSet<const Value *, 16>& KnownPoison) {
auto *NotPoison = getGuaranteedNonFullPoisonOp(I);
return (NotPoison && KnownPoison.count(NotPoison));
4384}


4387bool llvm::programUndefinedIfFullPoison(const Instruction *PoisonI) {
// We currently only look for uses of poison values within the same basic
// block, as that makes it easier to guarantee that the uses will be
// executed given that PoisonI is executed.
//
// FIXME: Expand this to consider uses beyond the same basic block. To do
// this, look out for the distinction between post-dominance and strong
// post-dominance.
const BasicBlock *BB = PoisonI->getParent();

// Set of instructions that we have proved will yield poison if PoisonI
// does.
SmallSet<const Value *, 16> YieldsPoison;
SmallSet<const BasicBlock *, 4> Visited;
YieldsPoison.insert(PoisonI);
Visited.insert(PoisonI->getParent());

BasicBlock::const_iterator Begin = PoisonI->getIterator(), End = BB->end();

unsigned Iter = 0;
while (Iter++ < MaxDepth) {
  for (auto &I : make_range(Begin, End)) {
    if (&I != PoisonI) {
      if (mustTriggerUB(&I, YieldsPoison))
        return true;
      if (!isGuaranteedToTransferExecutionToSuccessor(&I))
        return false;
    }

    // Mark poison that propagates from I through uses of I.
    if (YieldsPoison.count(&I)) {
      for (const User *User : I.users()) {
        const Instruction *UserI = cast<Instruction>(User);
        if (propagatesFullPoison(UserI))
          YieldsPoison.insert(User);
      }
    }
  }

  if (auto *NextBB = BB->getSingleSuccessor()) {
    if (Visited.insert(NextBB).second) {
      BB = NextBB;
      Begin = BB->getFirstNonPHI()->getIterator();
      End = BB->end();
      continue;
    }
  }

  break;
}
return false;
4438}

4440static bool isKnownNonNaN(const Value *V, FastMathFlags FMF) {
if (FMF.noNaNs())
  return true;

if (auto *C = dyn_cast<ConstantFP>(V))
  return !C->isNaN();

if (auto *C = dyn_cast<ConstantDataVector>(V)) {
  if (!C->getElementType()->isFloatingPointTy())
    return false;
  for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) {
    if (C->getElementAsAPFloat(I).isNaN())
      return false;
  }
  return true;
}

return false;
4458}

4460static bool isKnownNonZero(const Value *V) {
if (auto *C = dyn_cast<ConstantFP>(V))
  return !C->isZero();

if (auto *C = dyn_cast<ConstantDataVector>(V)) {
  if (!C->getElementType()->isFloatingPointTy())
    return false;
  for (unsigned I = 0, E = C->getNumElements(); I < E; ++I) {
    if (C->getElementAsAPFloat(I).isZero())
      return false;
  }
  return true;
}

return false;
4475}

4477/// Match clamp pattern for float types without care about NaNs or signed zeros.
4478/// Given non-min/max outer cmp/select from the clamp pattern this
4479/// function recognizes if it can be substitued by a "canonical" min/max
4480/// pattern.
4481static SelectPatternResult matchFastFloatClamp(CmpInst::Predicate Pred,
                                             Value *CmpLHS, Value *CmpRHS,
                                             Value *TrueVal, Value *FalseVal,
                                             Value *&LHS, Value *&RHS) {
// Try to match
//   X < C1 ? C1 : Min(X, C2) --> Max(C1, Min(X, C2))
//   X > C1 ? C1 : Max(X, C2) --> Min(C1, Max(X, C2))
// and return description of the outer Max/Min.

// First, check if select has inverse order:
if (CmpRHS == FalseVal) {
  std::swap(TrueVal, FalseVal);
  Pred = CmpInst::getInversePredicate(Pred);
}

// Assume success now. If there's no match, callers should not use these anyway.
LHS = TrueVal;
RHS = FalseVal;

const APFloat *FC1;
if (CmpRHS != TrueVal || !match(CmpRHS, m_APFloat(FC1)) || !FC1->isFinite())
  return {SPF_UNKNOWN, SPNB_NA, false};

const APFloat *FC2;
switch (Pred) {
case CmpInst::FCMP_OLT:
case CmpInst::FCMP_OLE:
case CmpInst::FCMP_ULT:
case CmpInst::FCMP_ULE:
  if (match(FalseVal,
            m_CombineOr(m_OrdFMin(m_Specific(CmpLHS), m_APFloat(FC2)),
                        m_UnordFMin(m_Specific(CmpLHS), m_APFloat(FC2)))) &&
      FC1->compare(*FC2) == APFloat::cmpResult::cmpLessThan)
    return {SPF_FMAXNUM, SPNB_RETURNS_ANY, false};
  break;
case CmpInst::FCMP_OGT:
case CmpInst::FCMP_OGE:
case CmpInst::FCMP_UGT:
case CmpInst::FCMP_UGE:
  if (match(FalseVal,
            m_CombineOr(m_OrdFMax(m_Specific(CmpLHS), m_APFloat(FC2)),
                        m_UnordFMax(m_Specific(CmpLHS), m_APFloat(FC2)))) &&
      FC1->compare(*FC2) == APFloat::cmpResult::cmpGreaterThan)
    return {SPF_FMINNUM, SPNB_RETURNS_ANY, false};
  break;
default:
  break;
}

return {SPF_UNKNOWN, SPNB_NA, false};
4531}

4533/// Recognize variations of:
4534///   CLAMP(v,l,h) ==> ((v) < (l) ? (l) : ((v) > (h) ? (h) : (v)))
4535static SelectPatternResult matchClamp(CmpInst::Predicate Pred,
                                    Value *CmpLHS, Value *CmpRHS,
                                    Value *TrueVal, Value *FalseVal) {
// Swap the select operands and predicate to match the patterns below.
if (CmpRHS != TrueVal) {
  Pred = ICmpInst::getSwappedPredicate(Pred);
  std::swap(TrueVal, FalseVal);
}
const APInt *C1;
if (CmpRHS == TrueVal && match(CmpRHS, m_APInt(C1))) {
  const APInt *C2;
  // (X <s C1) ? C1 : SMIN(X, C2) ==> SMAX(SMIN(X, C2), C1)
  if (match(FalseVal, m_SMin(m_Specific(CmpLHS), m_APInt(C2))) &&
      C1->slt(*C2) && Pred == CmpInst::ICMP_SLT)
    return {SPF_SMAX, SPNB_NA, false};

  // (X >s C1) ? C1 : SMAX(X, C2) ==> SMIN(SMAX(X, C2), C1)
  if (match(FalseVal, m_SMax(m_Specific(CmpLHS), m_APInt(C2))) &&
      C1->sgt(*C2) && Pred == CmpInst::ICMP_SGT)
    return {SPF_SMIN, SPNB_NA, false};

  // (X <u C1) ? C1 : UMIN(X, C2) ==> UMAX(UMIN(X, C2), C1)
  if (match(FalseVal, m_UMin(m_Specific(CmpLHS), m_APInt(C2))) &&
      C1->ult(*C2) && Pred == CmpInst::ICMP_ULT)
    return {SPF_UMAX, SPNB_NA, false};

  // (X >u C1) ? C1 : UMAX(X, C2) ==> UMIN(UMAX(X, C2), C1)
  if (match(FalseVal, m_UMax(m_Specific(CmpLHS), m_APInt(C2))) &&
      C1->ugt(*C2) && Pred == CmpInst::ICMP_UGT)
    return {SPF_UMIN, SPNB_NA, false};
}
return {SPF_UNKNOWN, SPNB_NA, false};
4567}

4569/// Recognize variations of:
4570///   a < c ? min(a,b) : min(b,c) ==> min(min(a,b),min(b,c))
4571static SelectPatternResult matchMinMaxOfMinMax(CmpInst::Predicate Pred,
                                             Value *CmpLHS, Value *CmpRHS,
                                             Value *TVal, Value *FVal,
                                             unsigned Depth) {
// TODO: Allow FP min/max with nnan/nsz.
assert(CmpInst::isIntPredicate(Pred) && "Expected integer comparison")((CmpInst::isIntPredicate(Pred) && "Expected integer comparison"
) ? static_cast<void> (0) : __assert_fail ("CmpInst::isIntPredicate(Pred) && \"Expected integer comparison\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 4576, __PRETTY_FUNCTION__));

Value *A, *B;
SelectPatternResult L = matchSelectPattern(TVal, A, B, nullptr, Depth + 1);
if (!SelectPatternResult::isMinOrMax(L.Flavor))
  return {SPF_UNKNOWN, SPNB_NA, false};

Value *C, *D;
SelectPatternResult R = matchSelectPattern(FVal, C, D, nullptr, Depth + 1);
if (L.Flavor != R.Flavor)
  return {SPF_UNKNOWN, SPNB_NA, false};

// We have something like: x Pred y ? min(a, b) : min(c, d).
// Try to match the compare to the min/max operations of the select operands.
// First, make sure we have the right compare predicate.
switch (L.Flavor) {
case SPF_SMIN:
  if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) {
    Pred = ICmpInst::getSwappedPredicate(Pred);
    std::swap(CmpLHS, CmpRHS);
  }
  if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
    break;
  return {SPF_UNKNOWN, SPNB_NA, false};
case SPF_SMAX:
  if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) {
    Pred = ICmpInst::getSwappedPredicate(Pred);
    std::swap(CmpLHS, CmpRHS);
  }
  if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE)
    break;
  return {SPF_UNKNOWN, SPNB_NA, false};
case SPF_UMIN:
  if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) {
    Pred = ICmpInst::getSwappedPredicate(Pred);
    std::swap(CmpLHS, CmpRHS);
  }
  if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE)
    break;
  return {SPF_UNKNOWN, SPNB_NA, false};
case SPF_UMAX:
  if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) {
    Pred = ICmpInst::getSwappedPredicate(Pred);
    std::swap(CmpLHS, CmpRHS);
  }
  if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE)
    break;
  return {SPF_UNKNOWN, SPNB_NA, false};
default:
  return {SPF_UNKNOWN, SPNB_NA, false};
}

// If there is a common operand in the already matched min/max and the other
// min/max operands match the compare operands (either directly or inverted),
// then this is min/max of the same flavor.

// a pred c ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b))
// ~c pred ~a ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b))
if (D == B) {
  if ((CmpLHS == A && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) &&
                                       match(A, m_Not(m_Specific(CmpRHS)))))
    return {L.Flavor, SPNB_NA, false};
}
// a pred d ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d))
// ~d pred ~a ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d))
if (C == B) {
  if ((CmpLHS == A && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) &&
                                       match(A, m_Not(m_Specific(CmpRHS)))))
    return {L.Flavor, SPNB_NA, false};
}
// b pred c ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a))
// ~c pred ~b ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a))
if (D == A) {
  if ((CmpLHS == B && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) &&
                                       match(B, m_Not(m_Specific(CmpRHS)))))
    return {L.Flavor, SPNB_NA, false};
}
// b pred d ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d))
// ~d pred ~b ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d))
if (C == A) {
  if ((CmpLHS == B && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) &&
                                       match(B, m_Not(m_Specific(CmpRHS)))))
    return {L.Flavor, SPNB_NA, false};
}

return {SPF_UNKNOWN, SPNB_NA, false};
4662}

4664/// Match non-obvious integer minimum and maximum sequences.
4665static SelectPatternResult matchMinMax(CmpInst::Predicate Pred,
                                     Value *CmpLHS, Value *CmpRHS,
                                     Value *TrueVal, Value *FalseVal,
                                     Value *&LHS, Value *&RHS,
                                     unsigned Depth) {
// Assume success. If there's no match, callers should not use these anyway.
LHS = TrueVal;
RHS = FalseVal;

SelectPatternResult SPR = matchClamp(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal);
if (SPR.Flavor != SelectPatternFlavor::SPF_UNKNOWN)
  return SPR;

SPR = matchMinMaxOfMinMax(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, Depth);
if (SPR.Flavor != SelectPatternFlavor::SPF_UNKNOWN)
  return SPR;

if (Pred != CmpInst::ICMP_SGT && Pred != CmpInst::ICMP_SLT)
  return {SPF_UNKNOWN, SPNB_NA, false};

// Z = X -nsw Y
// (X >s Y) ? 0 : Z ==> (Z >s 0) ? 0 : Z ==> SMIN(Z, 0)
// (X <s Y) ? 0 : Z ==> (Z <s 0) ? 0 : Z ==> SMAX(Z, 0)
if (match(TrueVal, m_Zero()) &&
    match(FalseVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS))))
  return {Pred == CmpInst::ICMP_SGT ? SPF_SMIN : SPF_SMAX, SPNB_NA, false};

// Z = X -nsw Y
// (X >s Y) ? Z : 0 ==> (Z >s 0) ? Z : 0 ==> SMAX(Z, 0)
// (X <s Y) ? Z : 0 ==> (Z <s 0) ? Z : 0 ==> SMIN(Z, 0)
if (match(FalseVal, m_Zero()) &&
    match(TrueVal, m_NSWSub(m_Specific(CmpLHS), m_Specific(CmpRHS))))
  return {Pred == CmpInst::ICMP_SGT ? SPF_SMAX : SPF_SMIN, SPNB_NA, false};

const APInt *C1;
if (!match(CmpRHS, m_APInt(C1)))
  return {SPF_UNKNOWN, SPNB_NA, false};

// An unsigned min/max can be written with a signed compare.
const APInt *C2;
if ((CmpLHS == TrueVal && match(FalseVal, m_APInt(C2))) ||
    (CmpLHS == FalseVal && match(TrueVal, m_APInt(C2)))) {
  // Is the sign bit set?
  // (X <s 0) ? X : MAXVAL ==> (X >u MAXVAL) ? X : MAXVAL ==> UMAX
  // (X <s 0) ? MAXVAL : X ==> (X >u MAXVAL) ? MAXVAL : X ==> UMIN
  if (Pred == CmpInst::ICMP_SLT && C1->isNullValue() &&
      C2->isMaxSignedValue())
    return {CmpLHS == TrueVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false};

  // Is the sign bit clear?
  // (X >s -1) ? MINVAL : X ==> (X <u MINVAL) ? MINVAL : X ==> UMAX
  // (X >s -1) ? X : MINVAL ==> (X <u MINVAL) ? X : MINVAL ==> UMIN
  if (Pred == CmpInst::ICMP_SGT && C1->isAllOnesValue() &&
      C2->isMinSignedValue())
    return {CmpLHS == FalseVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false};
}

// Look through 'not' ops to find disguised signed min/max.
// (X >s C) ? ~X : ~C ==> (~X <s ~C) ? ~X : ~C ==> SMIN(~X, ~C)
// (X <s C) ? ~X : ~C ==> (~X >s ~C) ? ~X : ~C ==> SMAX(~X, ~C)
if (match(TrueVal, m_Not(m_Specific(CmpLHS))) &&
    match(FalseVal, m_APInt(C2)) && ~(*C1) == *C2)
  return {Pred == CmpInst::ICMP_SGT ? SPF_SMIN : SPF_SMAX, SPNB_NA, false};

// (X >s C) ? ~C : ~X ==> (~X <s ~C) ? ~C : ~X ==> SMAX(~C, ~X)
// (X <s C) ? ~C : ~X ==> (~X >s ~C) ? ~C : ~X ==> SMIN(~C, ~X)
if (match(FalseVal, m_Not(m_Specific(CmpLHS))) &&
    match(TrueVal, m_APInt(C2)) && ~(*C1) == *C2)
  return {Pred == CmpInst::ICMP_SGT ? SPF_SMAX : SPF_SMIN, SPNB_NA, false};

return {SPF_UNKNOWN, SPNB_NA, false};
4736}

4738bool llvm::isKnownNegation(const Value *X, const Value *Y, bool NeedNSW) {
assert(X && Y && "Invalid operand")((X && Y && "Invalid operand") ? static_cast<
void> (0) : __assert_fail ("X && Y && \"Invalid operand\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 4739, __PRETTY_FUNCTION__));

// X = sub (0, Y) || X = sub nsw (0, Y)
if ((!NeedNSW && match(X, m_Sub(m_ZeroInt(), m_Specific(Y)))) ||
    (NeedNSW && match(X, m_NSWSub(m_ZeroInt(), m_Specific(Y)))))
  return true;

// Y = sub (0, X) || Y = sub nsw (0, X)
if ((!NeedNSW && match(Y, m_Sub(m_ZeroInt(), m_Specific(X)))) ||
    (NeedNSW && match(Y, m_NSWSub(m_ZeroInt(), m_Specific(X)))))
  return true;

// X = sub (A, B), Y = sub (B, A) || X = sub nsw (A, B), Y = sub nsw (B, A)
Value *A, *B;
return (!NeedNSW && (match(X, m_Sub(m_Value(A), m_Value(B))) &&
                      match(Y, m_Sub(m_Specific(B), m_Specific(A))))) ||
       (NeedNSW && (match(X, m_NSWSub(m_Value(A), m_Value(B))) &&
                     match(Y, m_NSWSub(m_Specific(B), m_Specific(A)))));
4757}

4759static SelectPatternResult matchSelectPattern(CmpInst::Predicate Pred,
                                            FastMathFlags FMF,
                                            Value *CmpLHS, Value *CmpRHS,
                                            Value *TrueVal, Value *FalseVal,
                                            Value *&LHS, Value *&RHS,
                                            unsigned Depth) {
if (CmpInst::isFPPredicate(Pred)) {
  // IEEE-754 ignores the sign of 0.0 in comparisons. So if the select has one
  // 0.0 operand, set the compare's 0.0 operands to that same value for the
  // purpose of identifying min/max. Disregard vector constants with undefined
  // elements because those can not be back-propagated for analysis.
  Value *OutputZeroVal = nullptr;
  if (match(TrueVal, m_AnyZeroFP()) && !match(FalseVal, m_AnyZeroFP()) &&
      !cast<Constant>(TrueVal)->containsUndefElement())
    OutputZeroVal = TrueVal;
  else if (match(FalseVal, m_AnyZeroFP()) && !match(TrueVal, m_AnyZeroFP()) &&
           !cast<Constant>(FalseVal)->containsUndefElement())
    OutputZeroVal = FalseVal;

  if (OutputZeroVal) {
    if (match(CmpLHS, m_AnyZeroFP()))
      CmpLHS = OutputZeroVal;
    if (match(CmpRHS, m_AnyZeroFP()))
      CmpRHS = OutputZeroVal;
  }
}

LHS = CmpLHS;
RHS = CmpRHS;

// Signed zero may return inconsistent results between implementations.
//  (0.0 <= -0.0) ? 0.0 : -0.0 // Returns 0.0
//  minNum(0.0, -0.0)          // May return -0.0 or 0.0 (IEEE 754-2008 5.3.1)
// Therefore, we behave conservatively and only proceed if at least one of the
// operands is known to not be zero or if we don't care about signed zero.
switch (Pred) {
default: break;
// FIXME: Include OGT/OLT/UGT/ULT.
case CmpInst::FCMP_OGE: case CmpInst::FCMP_OLE:
case CmpInst::FCMP_UGE: case CmpInst::FCMP_ULE:
  if (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) &&
      !isKnownNonZero(CmpRHS))
    return {SPF_UNKNOWN, SPNB_NA, false};
}

SelectPatternNaNBehavior NaNBehavior = SPNB_NA;
bool Ordered = false;

// When given one NaN and one non-NaN input:
//   - maxnum/minnum (C99 fmaxf()/fminf()) return the non-NaN input.
//   - A simple C99 (a < b ? a : b) construction will return 'b' (as the
//     ordered comparison fails), which could be NaN or non-NaN.
// so here we discover exactly what NaN behavior is required/accepted.
if (CmpInst::isFPPredicate(Pred)) {
  bool LHSSafe = isKnownNonNaN(CmpLHS, FMF);
  bool RHSSafe = isKnownNonNaN(CmpRHS, FMF);

  if (LHSSafe && RHSSafe) {
    // Both operands are known non-NaN.
    NaNBehavior = SPNB_RETURNS_ANY;
  } else if (CmpInst::isOrdered(Pred)) {
    // An ordered comparison will return false when given a NaN, so it
    // returns the RHS.
    Ordered = true;
    if (LHSSafe)
      // LHS is non-NaN, so if RHS is NaN then NaN will be returned.
      NaNBehavior = SPNB_RETURNS_NAN;
    else if (RHSSafe)
      NaNBehavior = SPNB_RETURNS_OTHER;
    else
      // Completely unsafe.
      return {SPF_UNKNOWN, SPNB_NA, false};
  } else {
    Ordered = false;
    // An unordered comparison will return true when given a NaN, so it
    // returns the LHS.
    if (LHSSafe)
      // LHS is non-NaN, so if RHS is NaN then non-NaN will be returned.
      NaNBehavior = SPNB_RETURNS_OTHER;
    else if (RHSSafe)
      NaNBehavior = SPNB_RETURNS_NAN;
    else
      // Completely unsafe.
      return {SPF_UNKNOWN, SPNB_NA, false};
  }
}

if (TrueVal == CmpRHS && FalseVal == CmpLHS) {
  std::swap(CmpLHS, CmpRHS);
  Pred = CmpInst::getSwappedPredicate(Pred);
  if (NaNBehavior == SPNB_RETURNS_NAN)
    NaNBehavior = SPNB_RETURNS_OTHER;
  else if (NaNBehavior == SPNB_RETURNS_OTHER)
    NaNBehavior = SPNB_RETURNS_NAN;
  Ordered = !Ordered;
}

// ([if]cmp X, Y) ? X : Y
if (TrueVal == CmpLHS && FalseVal == CmpRHS) {
  switch (Pred) {
  default: return {SPF_UNKNOWN, SPNB_NA, false}; // Equality.
  case ICmpInst::ICMP_UGT:
  case ICmpInst::ICMP_UGE: return {SPF_UMAX, SPNB_NA, false};
  case ICmpInst::ICMP_SGT:
  case ICmpInst::ICMP_SGE: return {SPF_SMAX, SPNB_NA, false};
  case ICmpInst::ICMP_ULT:
  case ICmpInst::ICMP_ULE: return {SPF_UMIN, SPNB_NA, false};
  case ICmpInst::ICMP_SLT:
  case ICmpInst::ICMP_SLE: return {SPF_SMIN, SPNB_NA, false};
  case FCmpInst::FCMP_UGT:
  case FCmpInst::FCMP_UGE:
  case FCmpInst::FCMP_OGT:
  case FCmpInst::FCMP_OGE: return {SPF_FMAXNUM, NaNBehavior, Ordered};
  case FCmpInst::FCMP_ULT:
  case FCmpInst::FCMP_ULE:
  case FCmpInst::FCMP_OLT:
  case FCmpInst::FCMP_OLE: return {SPF_FMINNUM, NaNBehavior, Ordered};
  }
}

if (isKnownNegation(TrueVal, FalseVal)) {
  // Sign-extending LHS does not change its sign, so TrueVal/FalseVal can
  // match against either LHS or sext(LHS).
  auto MaybeSExtCmpLHS =
      m_CombineOr(m_Specific(CmpLHS), m_SExt(m_Specific(CmpLHS)));
  auto ZeroOrAllOnes = m_CombineOr(m_ZeroInt(), m_AllOnes());
  auto ZeroOrOne = m_CombineOr(m_ZeroInt(), m_One());
  if (match(TrueVal, MaybeSExtCmpLHS)) {
    // Set the return values. If the compare uses the negated value (-X >s 0),
    // swap the return values because the negated value is always 'RHS'.
    LHS = TrueVal;
    RHS = FalseVal;
    if (match(CmpLHS, m_Neg(m_Specific(FalseVal))))
      std::swap(LHS, RHS);

    // (X >s 0) ? X : -X or (X >s -1) ? X : -X --> ABS(X)
    // (-X >s 0) ? -X : X or (-X >s -1) ? -X : X --> ABS(X)
    if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes))
      return {SPF_ABS, SPNB_NA, false};

    // (X >=s 0) ? X : -X or (X >=s 1) ? X : -X --> ABS(X)
    if (Pred == ICmpInst::ICMP_SGE && match(CmpRHS, ZeroOrOne))
      return {SPF_ABS, SPNB_NA, false};

    // (X <s 0) ? X : -X or (X <s 1) ? X : -X --> NABS(X)
    // (-X <s 0) ? -X : X or (-X <s 1) ? -X : X --> NABS(X)
    if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne))
      return {SPF_NABS, SPNB_NA, false};
  }
  else if (match(FalseVal, MaybeSExtCmpLHS)) {
    // Set the return values. If the compare uses the negated value (-X >s 0),
    // swap the return values because the negated value is always 'RHS'.
    LHS = FalseVal;
    RHS = TrueVal;
    if (match(CmpLHS, m_Neg(m_Specific(TrueVal))))
      std::swap(LHS, RHS);

    // (X >s 0) ? -X : X or (X >s -1) ? -X : X --> NABS(X)
    // (-X >s 0) ? X : -X or (-X >s -1) ? X : -X --> NABS(X)
    if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes))
      return {SPF_NABS, SPNB_NA, false};

    // (X <s 0) ? -X : X or (X <s 1) ? -X : X --> ABS(X)
    // (-X <s 0) ? X : -X or (-X <s 1) ? X : -X --> ABS(X)
    if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne))
      return {SPF_ABS, SPNB_NA, false};
  }
}

if (CmpInst::isIntPredicate(Pred))
  return matchMinMax(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, LHS, RHS, Depth);

// According to (IEEE 754-2008 5.3.1), minNum(0.0, -0.0) and similar
// may return either -0.0 or 0.0, so fcmp/select pair has stricter
// semantics than minNum. Be conservative in such case.
if (NaNBehavior != SPNB_RETURNS_ANY ||
    (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) &&
     !isKnownNonZero(CmpRHS)))
  return {SPF_UNKNOWN, SPNB_NA, false};

return matchFastFloatClamp(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal, LHS, RHS);
4940}

4942/// Helps to match a select pattern in case of a type mismatch.
4943///
4944/// The function processes the case when type of true and false values of a
4945/// select instruction differs from type of the cmp instruction operands because
4946/// of a cast instruction. The function checks if it is legal to move the cast
4947/// operation after "select". If yes, it returns the new second value of
4948/// "select" (with the assumption that cast is moved):
4949/// 1. As operand of cast instruction when both values of "select" are same cast
4950/// instructions.
4951/// 2. As restored constant (by applying reverse cast operation) when the first
4952/// value of the "select" is a cast operation and the second value is a
4953/// constant.
4954/// NOTE: We return only the new second value because the first value could be
4955/// accessed as operand of cast instruction.
4956static Value *lookThroughCast(CmpInst *CmpI, Value *V1, Value *V2,
                            Instruction::CastOps *CastOp) {
auto *Cast1 = dyn_cast<CastInst>(V1);
if (!Cast1)
  return nullptr;

*CastOp = Cast1->getOpcode();
Type *SrcTy = Cast1->getSrcTy();
if (auto *Cast2 = dyn_cast<CastInst>(V2)) {
  // If V1 and V2 are both the same cast from the same type, look through V1.
  if (*CastOp == Cast2->getOpcode() && SrcTy == Cast2->getSrcTy())
    return Cast2->getOperand(0);
  return nullptr;
}

auto *C = dyn_cast<Constant>(V2);
if (!C)
  return nullptr;

Constant *CastedTo = nullptr;
switch (*CastOp) {
case Instruction::ZExt:
  if (CmpI->isUnsigned())
    CastedTo = ConstantExpr::getTrunc(C, SrcTy);
  break;
case Instruction::SExt:
  if (CmpI->isSigned())
    CastedTo = ConstantExpr::getTrunc(C, SrcTy, true);
  break;
case Instruction::Trunc:
  Constant *CmpConst;
  if (match(CmpI->getOperand(1), m_Constant(CmpConst)) &&
      CmpConst->getType() == SrcTy) {
    // Here we have the following case:
    //
    //   %cond = cmp iN %x, CmpConst
    //   %tr = trunc iN %x to iK
    //   %narrowsel = select i1 %cond, iK %t, iK C
    //
    // We can always move trunc after select operation:
    //
    //   %cond = cmp iN %x, CmpConst
    //   %widesel = select i1 %cond, iN %x, iN CmpConst
    //   %tr = trunc iN %widesel to iK
    //
    // Note that C could be extended in any way because we don't care about
    // upper bits after truncation. It can't be abs pattern, because it would
    // look like:
    //
    //   select i1 %cond, x, -x.
    //
    // So only min/max pattern could be matched. Such match requires widened C
    // == CmpConst. That is why set widened C = CmpConst, condition trunc
    // CmpConst == C is checked below.
    CastedTo = CmpConst;
  } else {
    CastedTo = ConstantExpr::getIntegerCast(C, SrcTy, CmpI->isSigned());
  }
  break;
case Instruction::FPTrunc:
  CastedTo = ConstantExpr::getFPExtend(C, SrcTy, true);
  break;
case Instruction::FPExt:
  CastedTo = ConstantExpr::getFPTrunc(C, SrcTy, true);
  break;
case Instruction::FPToUI:
  CastedTo = ConstantExpr::getUIToFP(C, SrcTy, true);
  break;
case Instruction::FPToSI:
  CastedTo = ConstantExpr::getSIToFP(C, SrcTy, true);
  break;
case Instruction::UIToFP:
  CastedTo = ConstantExpr::getFPToUI(C, SrcTy, true);
  break;
case Instruction::SIToFP:
  CastedTo = ConstantExpr::getFPToSI(C, SrcTy, true);
  break;
default:
  break;
}

if (!CastedTo)
  return nullptr;

// Make sure the cast doesn't lose any information.
Constant *CastedBack =
    ConstantExpr::getCast(*CastOp, CastedTo, C->getType(), true);
if (CastedBack != C)
  return nullptr;

return CastedTo;
5047}

5049SelectPatternResult llvm::matchSelectPattern(Value *V, Value *&LHS, Value *&RHS,
                                           Instruction::CastOps *CastOp,
                                           unsigned Depth) {
if (Depth >= MaxDepth)
  return {SPF_UNKNOWN, SPNB_NA, false};

SelectInst *SI = dyn_cast<SelectInst>(V);
if (!SI) return {SPF_UNKNOWN, SPNB_NA, false};

CmpInst *CmpI = dyn_cast<CmpInst>(SI->getCondition());
if (!CmpI) return {SPF_UNKNOWN, SPNB_NA, false};

Value *TrueVal = SI->getTrueValue();
Value *FalseVal = SI->getFalseValue();

return llvm::matchDecomposedSelectPattern(CmpI, TrueVal, FalseVal, LHS, RHS,
                                          CastOp, Depth);
5066}

5068SelectPatternResult llvm::matchDecomposedSelectPattern(
  CmpInst *CmpI, Value *TrueVal, Value *FalseVal, Value *&LHS, Value *&RHS,
  Instruction::CastOps *CastOp, unsigned Depth) {
CmpInst::Predicate Pred = CmpI->getPredicate();
Value *CmpLHS = CmpI->getOperand(0);
Value *CmpRHS = CmpI->getOperand(1);
FastMathFlags FMF;
if (isa<FPMathOperator>(CmpI))
  FMF = CmpI->getFastMathFlags();

// Bail out early.
if (CmpI->isEquality())
  return {SPF_UNKNOWN, SPNB_NA, false};

// Deal with type mismatches.
if (CastOp && CmpLHS->getType() != TrueVal->getType()) {
  if (Value *C = lookThroughCast(CmpI, TrueVal, FalseVal, CastOp)) {
    // If this is a potential fmin/fmax with a cast to integer, then ignore
    // -0.0 because there is no corresponding integer value.
    if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI)
      FMF.setNoSignedZeros();
    return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS,
                                cast<CastInst>(TrueVal)->getOperand(0), C,
                                LHS, RHS, Depth);
  }
  if (Value *C = lookThroughCast(CmpI, FalseVal, TrueVal, CastOp)) {
    // If this is a potential fmin/fmax with a cast to integer, then ignore
    // -0.0 because there is no corresponding integer value.
    if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI)
      FMF.setNoSignedZeros();
    return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS,
                                C, cast<CastInst>(FalseVal)->getOperand(0),
                                LHS, RHS, Depth);
  }
}
return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, TrueVal, FalseVal,
                            LHS, RHS, Depth);
5105}

5107CmpInst::Predicate llvm::getMinMaxPred(SelectPatternFlavor SPF, bool Ordered) {
if (SPF == SPF_SMIN) return ICmpInst::ICMP_SLT;
if (SPF == SPF_UMIN) return ICmpInst::ICMP_ULT;
if (SPF == SPF_SMAX) return ICmpInst::ICMP_SGT;
if (SPF == SPF_UMAX) return ICmpInst::ICMP_UGT;
if (SPF == SPF_FMINNUM)
  return Ordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT;
if (SPF == SPF_FMAXNUM)
  return Ordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT;
llvm_unreachable("unhandled!")::llvm::llvm_unreachable_internal("unhandled!", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5116);
5117}

5119SelectPatternFlavor llvm::getInverseMinMaxFlavor(SelectPatternFlavor SPF) {
if (SPF == SPF_SMIN) return SPF_SMAX;
if (SPF == SPF_UMIN) return SPF_UMAX;
if (SPF == SPF_SMAX) return SPF_SMIN;
if (SPF == SPF_UMAX) return SPF_UMIN;
llvm_unreachable("unhandled!")::llvm::llvm_unreachable_internal("unhandled!", "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5124);
5125}

5127CmpInst::Predicate llvm::getInverseMinMaxPred(SelectPatternFlavor SPF) {
return getMinMaxPred(getInverseMinMaxFlavor(SPF));
5129}

5131/// Return true if "icmp Pred LHS RHS" is always true.
5132static bool isTruePredicate(CmpInst::Predicate Pred, const Value *LHS,
                          const Value *RHS, const DataLayout &DL,
                          unsigned Depth) {
assert(!LHS->getType()->isVectorTy() && "TODO: extend to handle vectors!")((!LHS->getType()->isVectorTy() && "TODO: extend to handle vectors!"
) ? static_cast<void> (0) : __assert_fail ("!LHS->getType()->isVectorTy() && \"TODO: extend to handle vectors!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5135, __PRETTY_FUNCTION__));
if (ICmpInst::isTrueWhenEqual(Pred) && LHS == RHS)
  return true;

switch (Pred) {
default:
  return false;

case CmpInst::ICMP_SLE: {
  const APInt *C;

  // LHS s<= LHS +_{nsw} C   if C >= 0
  if (match(RHS, m_NSWAdd(m_Specific(LHS), m_APInt(C))))
    return !C->isNegative();
  return false;
}

case CmpInst::ICMP_ULE: {
  const APInt *C;

  // LHS u<= LHS +_{nuw} C   for any C
  if (match(RHS, m_NUWAdd(m_Specific(LHS), m_APInt(C))))
    return true;

  // Match A to (X +_{nuw} CA) and B to (X +_{nuw} CB)
  auto MatchNUWAddsToSameValue = [&](const Value *A, const Value *B,
                                     const Value *&X,
                                     const APInt *&CA, const APInt *&CB) {
    if (match(A, m_NUWAdd(m_Value(X), m_APInt(CA))) &&
        match(B, m_NUWAdd(m_Specific(X), m_APInt(CB))))
      return true;

    // If X & C == 0 then (X | C) == X +_{nuw} C
    if (match(A, m_Or(m_Value(X), m_APInt(CA))) &&
        match(B, m_Or(m_Specific(X), m_APInt(CB)))) {
      KnownBits Known(CA->getBitWidth());
      computeKnownBits(X, Known, DL, Depth + 1, /*AC*/ nullptr,
                       /*CxtI*/ nullptr, /*DT*/ nullptr);
      if (CA->isSubsetOf(Known.Zero) && CB->isSubsetOf(Known.Zero))
        return true;
    }

    return false;
  };

  const Value *X;
  const APInt *CLHS, *CRHS;
  if (MatchNUWAddsToSameValue(LHS, RHS, X, CLHS, CRHS))
    return CLHS->ule(*CRHS);

  return false;
}
}
5188}

5190/// Return true if "icmp Pred BLHS BRHS" is true whenever "icmp Pred
5191/// ALHS ARHS" is true.  Otherwise, return None.
5192static Optional<bool>
5193isImpliedCondOperands(CmpInst::Predicate Pred, const Value *ALHS,
                    const Value *ARHS, const Value *BLHS, const Value *BRHS,
                    const DataLayout &DL, unsigned Depth) {
switch (Pred) {
default:
  return None;

case CmpInst::ICMP_SLT:
case CmpInst::ICMP_SLE:
  if (isTruePredicate(CmpInst::ICMP_SLE, BLHS, ALHS, DL, Depth) &&
      isTruePredicate(CmpInst::ICMP_SLE, ARHS, BRHS, DL, Depth))
    return true;
  return None;

case CmpInst::ICMP_ULT:
case CmpInst::ICMP_ULE:
  if (isTruePredicate(CmpInst::ICMP_ULE, BLHS, ALHS, DL, Depth) &&
      isTruePredicate(CmpInst::ICMP_ULE, ARHS, BRHS, DL, Depth))
    return true;
  return None;
}
5214}

5216/// Return true if the operands of the two compares match.  IsSwappedOps is true
5217/// when the operands match, but are swapped.
5218static bool isMatchingOps(const Value *ALHS, const Value *ARHS,
                        const Value *BLHS, const Value *BRHS,
                        bool &IsSwappedOps) {

bool IsMatchingOps = (ALHS == BLHS && ARHS == BRHS);
IsSwappedOps = (ALHS == BRHS && ARHS == BLHS);
return IsMatchingOps || IsSwappedOps;
5225}

5227/// Return true if "icmp1 APred X, Y" implies "icmp2 BPred X, Y" is true.
5228/// Return false if "icmp1 APred X, Y" implies "icmp2 BPred X, Y" is false.
5229/// Otherwise, return None if we can't infer anything.
5230static Optional<bool> isImpliedCondMatchingOperands(CmpInst::Predicate APred,
                                                  CmpInst::Predicate BPred,
                                                  bool AreSwappedOps) {
// Canonicalize the predicate as if the operands were not commuted.
if (AreSwappedOps)
  BPred = ICmpInst::getSwappedPredicate(BPred);

if (CmpInst::isImpliedTrueByMatchingCmp(APred, BPred))
  return true;
if (CmpInst::isImpliedFalseByMatchingCmp(APred, BPred))
  return false;

return None;
5243}

5245/// Return true if "icmp APred X, C1" implies "icmp BPred X, C2" is true.
5246/// Return false if "icmp APred X, C1" implies "icmp BPred X, C2" is false.
5247/// Otherwise, return None if we can't infer anything.
5248static Optional<bool>
5249isImpliedCondMatchingImmOperands(CmpInst::Predicate APred,
                               const ConstantInt *C1,
                               CmpInst::Predicate BPred,
                               const ConstantInt *C2) {
ConstantRange DomCR =
    ConstantRange::makeExactICmpRegion(APred, C1->getValue());
ConstantRange CR =
    ConstantRange::makeAllowedICmpRegion(BPred, C2->getValue());
ConstantRange Intersection = DomCR.intersectWith(CR);
ConstantRange Difference = DomCR.difference(CR);
if (Intersection.isEmptySet())
  return false;
if (Difference.isEmptySet())
  return true;
return None;
5264}

5266/// Return true if LHS implies RHS is true.  Return false if LHS implies RHS is
5267/// false.  Otherwise, return None if we can't infer anything.
5268static Optional<bool> isImpliedCondICmps(const ICmpInst *LHS,
                                       const ICmpInst *RHS,
                                       const DataLayout &DL, bool LHSIsTrue,
                                       unsigned Depth) {
Value *ALHS = LHS->getOperand(0);
Value *ARHS = LHS->getOperand(1);
// The rest of the logic assumes the LHS condition is true.  If that's not the
// case, invert the predicate to make it so.
ICmpInst::Predicate APred =
    LHSIsTrue ? LHS->getPredicate() : LHS->getInversePredicate();

Value *BLHS = RHS->getOperand(0);
Value *BRHS = RHS->getOperand(1);
ICmpInst::Predicate BPred = RHS->getPredicate();

// Can we infer anything when the two compares have matching operands?
bool AreSwappedOps;
if (isMatchingOps(ALHS, ARHS, BLHS, BRHS, AreSwappedOps)) {
  if (Optional<bool> Implication = isImpliedCondMatchingOperands(
          APred, BPred, AreSwappedOps))
    return Implication;
  // No amount of additional analysis will infer the second condition, so
  // early exit.
  return None;
}

// Can we infer anything when the LHS operands match and the RHS operands are
// constants (not necessarily matching)?
if (ALHS == BLHS && isa<ConstantInt>(ARHS) && isa<ConstantInt>(BRHS)) {
  if (Optional<bool> Implication = isImpliedCondMatchingImmOperands(
          APred, cast<ConstantInt>(ARHS), BPred, cast<ConstantInt>(BRHS)))
    return Implication;
  // No amount of additional analysis will infer the second condition, so
  // early exit.
  return None;
}

if (APred == BPred)
  return isImpliedCondOperands(APred, ALHS, ARHS, BLHS, BRHS, DL, Depth);
return None;
5308}

5310/// Return true if LHS implies RHS is true.  Return false if LHS implies RHS is
5311/// false.  Otherwise, return None if we can't infer anything.  We expect the
5312/// RHS to be an icmp and the LHS to be an 'and' or an 'or' instruction.
5313static Optional<bool> isImpliedCondAndOr(const BinaryOperator *LHS,
                                       const ICmpInst *RHS,
                                       const DataLayout &DL, bool LHSIsTrue,
                                       unsigned Depth) {
// The LHS must be an 'or' or an 'and' instruction.
assert((LHS->getOpcode() == Instruction::And ||(((LHS->getOpcode() == Instruction::And || LHS->getOpcode
() == Instruction::Or) && "Expected LHS to be 'and' or 'or'."
) ? static_cast<void> (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or) && \"Expected LHS to be 'and' or 'or'.\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5320, __PRETTY_FUNCTION__))
        LHS->getOpcode() == Instruction::Or) &&(((LHS->getOpcode() == Instruction::And || LHS->getOpcode
() == Instruction::Or) && "Expected LHS to be 'and' or 'or'."
) ? static_cast<void> (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or) && \"Expected LHS to be 'and' or 'or'.\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5320, __PRETTY_FUNCTION__))
       "Expected LHS to be 'and' or 'or'.")(((LHS->getOpcode() == Instruction::And || LHS->getOpcode
() == Instruction::Or) && "Expected LHS to be 'and' or 'or'."
) ? static_cast<void> (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or) && \"Expected LHS to be 'and' or 'or'.\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5320, __PRETTY_FUNCTION__));

assert(Depth <= MaxDepth && "Hit recursion limit")((Depth <= MaxDepth && "Hit recursion limit") ? static_cast
<void> (0) : __assert_fail ("Depth <= MaxDepth && \"Hit recursion limit\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5322, __PRETTY_FUNCTION__));

// If the result of an 'or' is false, then we know both legs of the 'or' are
// false.  Similarly, if the result of an 'and' is true, then we know both
// legs of the 'and' are true.
Value *ALHS, *ARHS;
if ((!LHSIsTrue && match(LHS, m_Or(m_Value(ALHS), m_Value(ARHS)))) ||
    (LHSIsTrue && match(LHS, m_And(m_Value(ALHS), m_Value(ARHS))))) {
  // FIXME: Make this non-recursion.
  if (Optional<bool> Implication =
          isImpliedCondition(ALHS, RHS, DL, LHSIsTrue, Depth + 1))
    return Implication;
  if (Optional<bool> Implication =
          isImpliedCondition(ARHS, RHS, DL, LHSIsTrue, Depth + 1))
    return Implication;
  return None;
}
return None;
5340}

5342Optional<bool> llvm::isImpliedCondition(const Value *LHS, const Value *RHS,
                                      const DataLayout &DL, bool LHSIsTrue,
                                      unsigned Depth) {
// Bail out when we hit the limit.
if (Depth == MaxDepth)
  return None;

// A mismatch occurs when we compare a scalar cmp to a vector cmp, for
// example.
if (LHS->getType() != RHS->getType())
  return None;

Type *OpTy = LHS->getType();
assert(OpTy->isIntOrIntVectorTy(1) && "Expected integer type only!")((OpTy->isIntOrIntVectorTy(1) && "Expected integer type only!"
) ? static_cast<void> (0) : __assert_fail ("OpTy->isIntOrIntVectorTy(1) && \"Expected integer type only!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5355, __PRETTY_FUNCTION__));

// LHS ==> RHS by definition
if (LHS == RHS)
  return LHSIsTrue;

// FIXME: Extending the code below to handle vectors.
if (OpTy->isVectorTy())
  return None;

assert(OpTy->isIntegerTy(1) && "implied by above")((OpTy->isIntegerTy(1) && "implied by above") ? static_cast
<void> (0) : __assert_fail ("OpTy->isIntegerTy(1) && \"implied by above\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5365, __PRETTY_FUNCTION__));

// Both LHS and RHS are icmps.
const ICmpInst *LHSCmp = dyn_cast<ICmpInst>(LHS);
const ICmpInst *RHSCmp = dyn_cast<ICmpInst>(RHS);
if (LHSCmp && RHSCmp)
  return isImpliedCondICmps(LHSCmp, RHSCmp, DL, LHSIsTrue, Depth);

// The LHS should be an 'or' or an 'and' instruction.  We expect the RHS to be
// an icmp. FIXME: Add support for and/or on the RHS.
const BinaryOperator *LHSBO = dyn_cast<BinaryOperator>(LHS);
if (LHSBO && RHSCmp) {
  if ((LHSBO->getOpcode() == Instruction::And ||
       LHSBO->getOpcode() == Instruction::Or))
    return isImpliedCondAndOr(LHSBO, RHSCmp, DL, LHSIsTrue, Depth);
}
return None;
5382}

5384Optional<bool> llvm::isImpliedByDomCondition(const Value *Cond,
                                           const Instruction *ContextI,
                                           const DataLayout &DL) {
assert(Cond->getType()->isIntOrIntVectorTy(1) && "Condition must be bool")((Cond->getType()->isIntOrIntVectorTy(1) && "Condition must be bool"
) ? static_cast<void> (0) : __assert_fail ("Cond->getType()->isIntOrIntVectorTy(1) && \"Condition must be bool\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5387, __PRETTY_FUNCTION__));
if (!ContextI || !ContextI->getParent())
  return None;

// TODO: This is a poor/cheap way to determine dominance. Should we use a
// dominator tree (eg, from a SimplifyQuery) instead?
const BasicBlock *ContextBB = ContextI->getParent();
const BasicBlock *PredBB = ContextBB->getSinglePredecessor();
if (!PredBB)
  return None;

// We need a conditional branch in the predecessor.
Value *PredCond;
BasicBlock *TrueBB, *FalseBB;
if (!match(PredBB->getTerminator(), m_Br(m_Value(PredCond), TrueBB, FalseBB)))
  return None;

// The branch should get simplified. Don't bother simplifying this condition.
if (TrueBB == FalseBB)
  return None;

assert((TrueBB == ContextBB || FalseBB == ContextBB) &&(((TrueBB == ContextBB || FalseBB == ContextBB) && "Predecessor block does not point to successor?"
) ? static_cast<void> (0) : __assert_fail ("(TrueBB == ContextBB || FalseBB == ContextBB) && \"Predecessor block does not point to successor?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5409, __PRETTY_FUNCTION__))
       "Predecessor block does not point to successor?")(((TrueBB == ContextBB || FalseBB == ContextBB) && "Predecessor block does not point to successor?"
) ? static_cast<void> (0) : __assert_fail ("(TrueBB == ContextBB || FalseBB == ContextBB) && \"Predecessor block does not point to successor?\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5409, __PRETTY_FUNCTION__));

// Is this condition implied by the predecessor condition?
bool CondIsTrue = TrueBB == ContextBB;
return isImpliedCondition(PredCond, Cond, DL, CondIsTrue);
5414}

5416static void setLimitsForBinOp(const BinaryOperator &BO, APInt &Lower,
                            APInt &Upper, const InstrInfoQuery &IIQ) {
unsigned Width = Lower.getBitWidth();
const APInt *C;
switch (BO.getOpcode()) {
case Instruction::Add:
  if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) {
    // FIXME: If we have both nuw and nsw, we should reduce the range further.
    if (IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(&BO))) {
      // 'add nuw x, C' produces [C, UINT_MAX].
      Lower = *C;
    } else if (IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(&BO))) {
      if (C->isNegative()) {
        // 'add nsw x, -C' produces [SINT_MIN, SINT_MAX - C].
        Lower = APInt::getSignedMinValue(Width);
        Upper = APInt::getSignedMaxValue(Width) + *C + 1;
      } else {
        // 'add nsw x, +C' produces [SINT_MIN + C, SINT_MAX].
        Lower = APInt::getSignedMinValue(Width) + *C;
        Upper = APInt::getSignedMaxValue(Width) + 1;
      }
    }
  }
  break;

case Instruction::And:
  if (match(BO.getOperand(1), m_APInt(C)))
    // 'and x, C' produces [0, C].
    Upper = *C + 1;
  break;

case Instruction::Or:
  if (match(BO.getOperand(1), m_APInt(C)))
    // 'or x, C' produces [C, UINT_MAX].
    Lower = *C;
  break;

case Instruction::AShr:
  if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) {
    // 'ashr x, C' produces [INT_MIN >> C, INT_MAX >> C].
    Lower = APInt::getSignedMinValue(Width).ashr(*C);
    Upper = APInt::getSignedMaxValue(Width).ashr(*C) + 1;
  } else if (match(BO.getOperand(0), m_APInt(C))) {
    unsigned ShiftAmount = Width - 1;
    if (!C->isNullValue() && IIQ.isExact(&BO))
      ShiftAmount = C->countTrailingZeros();
    if (C->isNegative()) {
      // 'ashr C, x' produces [C, C >> (Width-1)]
      Lower = *C;
      Upper = C->ashr(ShiftAmount) + 1;
    } else {
      // 'ashr C, x' produces [C >> (Width-1), C]
      Lower = C->ashr(ShiftAmount);
      Upper = *C + 1;
    }
  }
  break;

case Instruction::LShr:
  if (match(BO.getOperand(1), m_APInt(C)) && C->ult(Width)) {
    // 'lshr x, C' produces [0, UINT_MAX >> C].
    Upper = APInt::getAllOnesValue(Width).lshr(*C) + 1;
  } else if (match(BO.getOperand(0), m_APInt(C))) {
    // 'lshr C, x' produces [C >> (Width-1), C].
    unsigned ShiftAmount = Width - 1;
    if (!C->isNullValue() && IIQ.isExact(&BO))
      ShiftAmount = C->countTrailingZeros();
    Lower = C->lshr(ShiftAmount);
    Upper = *C + 1;
  }
  break;

case Instruction::Shl:
  if (match(BO.getOperand(0), m_APInt(C))) {
    if (IIQ.hasNoUnsignedWrap(&BO)) {
      // 'shl nuw C, x' produces [C, C << CLZ(C)]
      Lower = *C;
      Upper = Lower.shl(Lower.countLeadingZeros()) + 1;
    } else if (BO.hasNoSignedWrap()) { // TODO: What if both nuw+nsw?
      if (C->isNegative()) {
        // 'shl nsw C, x' produces [C << CLO(C)-1, C]
        unsigned ShiftAmount = C->countLeadingOnes() - 1;
        Lower = C->shl(ShiftAmount);
        Upper = *C + 1;
      } else {
        // 'shl nsw C, x' produces [C, C << CLZ(C)-1]
        unsigned ShiftAmount = C->countLeadingZeros() - 1;
        Lower = *C;
        Upper = C->shl(ShiftAmount) + 1;
      }
    }
  }
  break;

case Instruction::SDiv:
  if (match(BO.getOperand(1), m_APInt(C))) {
    APInt IntMin = APInt::getSignedMinValue(Width);
    APInt IntMax = APInt::getSignedMaxValue(Width);
    if (C->isAllOnesValue()) {
      // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX]
      //    where C != -1 and C != 0 and C != 1
      Lower = IntMin + 1;
      Upper = IntMax + 1;
    } else if (C->countLeadingZeros() < Width - 1) {
      // 'sdiv x, C' produces [INT_MIN / C, INT_MAX / C]
      //    where C != -1 and C != 0 and C != 1
      Lower = IntMin.sdiv(*C);
      Upper = IntMax.sdiv(*C);
      if (Lower.sgt(Upper))
        std::swap(Lower, Upper);
      Upper = Upper + 1;
      assert(Upper != Lower && "Upper part of range has wrapped!")((Upper != Lower && "Upper part of range has wrapped!"
) ? static_cast<void> (0) : __assert_fail ("Upper != Lower && \"Upper part of range has wrapped!\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5527, __PRETTY_FUNCTION__));
    }
  } else if (match(BO.getOperand(0), m_APInt(C))) {
    if (C->isMinSignedValue()) {
      // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2].
      Lower = *C;
      Upper = Lower.lshr(1) + 1;
    } else {
      // 'sdiv C, x' produces [-|C|, |C|].
      Upper = C->abs() + 1;
      Lower = (-Upper) + 1;
    }
  }
  break;

case Instruction::UDiv:
  if (match(BO.getOperand(1), m_APInt(C)) && !C->isNullValue()) {
    // 'udiv x, C' produces [0, UINT_MAX / C].
    Upper = APInt::getMaxValue(Width).udiv(*C) + 1;
  } else if (match(BO.getOperand(0), m_APInt(C))) {
    // 'udiv C, x' produces [0, C].
    Upper = *C + 1;
  }
  break;

case Instruction::SRem:
  if (match(BO.getOperand(1), m_APInt(C))) {
    // 'srem x, C' produces (-|C|, |C|).
    Upper = C->abs();
    Lower = (-Upper) + 1;
  }
  break;

case Instruction::URem:
  if (match(BO.getOperand(1), m_APInt(C)))
    // 'urem x, C' produces [0, C).
    Upper = *C;
  break;

default:
  break;
}
5569}

5571static void setLimitsForIntrinsic(const IntrinsicInst &II, APInt &Lower,
                                APInt &Upper) {
unsigned Width = Lower.getBitWidth();
const APInt *C;
switch (II.getIntrinsicID()) {
case Intrinsic::uadd_sat:
  // uadd.sat(x, C) produces [C, UINT_MAX].
  if (match(II.getOperand(0), m_APInt(C)) ||
      match(II.getOperand(1), m_APInt(C)))
    Lower = *C;
  break;
case Intrinsic::sadd_sat:
  if (match(II.getOperand(0), m_APInt(C)) ||
      match(II.getOperand(1), m_APInt(C))) {
    if (C->isNegative()) {
      // sadd.sat(x, -C) produces [SINT_MIN, SINT_MAX + (-C)].
      Lower = APInt::getSignedMinValue(Width);
      Upper = APInt::getSignedMaxValue(Width) + *C + 1;
    } else {
      // sadd.sat(x, +C) produces [SINT_MIN + C, SINT_MAX].
      Lower = APInt::getSignedMinValue(Width) + *C;
      Upper = APInt::getSignedMaxValue(Width) + 1;
    }
  }
  break;
case Intrinsic::usub_sat:
  // usub.sat(C, x) produces [0, C].
  if (match(II.getOperand(0), m_APInt(C)))
    Upper = *C + 1;
  // usub.sat(x, C) produces [0, UINT_MAX - C].
  else if (match(II.getOperand(1), m_APInt(C)))
    Upper = APInt::getMaxValue(Width) - *C + 1;
  break;
case Intrinsic::ssub_sat:
  if (match(II.getOperand(0), m_APInt(C))) {
    if (C->isNegative()) {
      // ssub.sat(-C, x) produces [SINT_MIN, -SINT_MIN + (-C)].
      Lower = APInt::getSignedMinValue(Width);
      Upper = *C - APInt::getSignedMinValue(Width) + 1;
    } else {
      // ssub.sat(+C, x) produces [-SINT_MAX + C, SINT_MAX].
      Lower = *C - APInt::getSignedMaxValue(Width);
      Upper = APInt::getSignedMaxValue(Width) + 1;
    }
  } else if (match(II.getOperand(1), m_APInt(C))) {
    if (C->isNegative()) {
      // ssub.sat(x, -C) produces [SINT_MIN - (-C), SINT_MAX]:
      Lower = APInt::getSignedMinValue(Width) - *C;
      Upper = APInt::getSignedMaxValue(Width) + 1;
    } else {
      // ssub.sat(x, +C) produces [SINT_MIN, SINT_MAX - C].
      Lower = APInt::getSignedMinValue(Width);
      Upper = APInt::getSignedMaxValue(Width) - *C + 1;
    }
  }
  break;
default:
  break;
}
5630}

5632static void setLimitsForSelectPattern(const SelectInst &SI, APInt &Lower,
                                    APInt &Upper, const InstrInfoQuery &IIQ) {
const Value *LHS, *RHS;
SelectPatternResult R = matchSelectPattern(&SI, LHS, RHS);
if (R.Flavor == SPF_UNKNOWN)
  return;

unsigned BitWidth = SI.getType()->getScalarSizeInBits();

if (R.Flavor == SelectPatternFlavor::SPF_ABS) {
  // If the negation part of the abs (in RHS) has the NSW flag,
  // then the result of abs(X) is [0..SIGNED_MAX],
  // otherwise it is [0..SIGNED_MIN], as -SIGNED_MIN == SIGNED_MIN.
  Lower = APInt::getNullValue(BitWidth);
  if (match(RHS, m_Neg(m_Specific(LHS))) &&
      IIQ.hasNoSignedWrap(cast<Instruction>(RHS)))
    Upper = APInt::getSignedMaxValue(BitWidth) + 1;
  else
    Upper = APInt::getSignedMinValue(BitWidth) + 1;
  return;
}

if (R.Flavor == SelectPatternFlavor::SPF_NABS) {
  // The result of -abs(X) is <= 0.
  Lower = APInt::getSignedMinValue(BitWidth);
  Upper = APInt(BitWidth, 1);
  return;
}

const APInt *C;
if (!match(LHS, m_APInt(C)) && !match(RHS, m_APInt(C)))
  return;

switch (R.Flavor) {
  case SPF_UMIN:
    Upper = *C + 1;
    break;
  case SPF_UMAX:
    Lower = *C;
    break;
  case SPF_SMIN:
    Lower = APInt::getSignedMinValue(BitWidth);
    Upper = *C + 1;
    break;
  case SPF_SMAX:
    Lower = *C;
    Upper = APInt::getSignedMaxValue(BitWidth) + 1;
    break;
  default:
    break;
}
5683}

5685ConstantRange llvm::computeConstantRange(const Value *V, bool UseInstrInfo) {
assert(V->getType()->isIntOrIntVectorTy() && "Expected integer instruction")((V->getType()->isIntOrIntVectorTy() && "Expected integer instruction"
) ? static_cast<void> (0) : __assert_fail ("V->getType()->isIntOrIntVectorTy() && \"Expected integer instruction\""
, "/build/llvm-toolchain-snapshot-10~svn372306/lib/Analysis/ValueTracking.cpp"
, 5686, __PRETTY_FUNCTION__));

const APInt *C;
if (match(V, m_APInt(C)))
  return ConstantRange(*C);

InstrInfoQuery IIQ(UseInstrInfo);
unsigned BitWidth = V->getType()->getScalarSizeInBits();
APInt Lower = APInt(BitWidth, 0);
APInt Upper = APInt(BitWidth, 0);
if (auto *BO = dyn_cast<BinaryOperator>(V))
  setLimitsForBinOp(*BO, Lower, Upper, IIQ);
else if (auto *II = dyn_cast<IntrinsicInst>(V))
  setLimitsForIntrinsic(*II, Lower, Upper);
else if (auto *SI = dyn_cast<SelectInst>(V))
  setLimitsForSelectPattern(*SI, Lower, Upper, IIQ);

ConstantRange CR = ConstantRange::getNonEmpty(Lower, Upper);

if (auto *I = dyn_cast<Instruction>(V))
  if (auto *Range = IIQ.getMetadata(I, LLVMContext::MD_range))
    CR = CR.intersectWith(getConstantRangeFromMetadata(*Range));

return CR;
5710}

5712static Optional<int64_t>
5713getOffsetFromIndex(const GEPOperator *GEP, unsigned Idx, const DataLayout &DL) {
// Skip over the first indices.
gep_type_iterator GTI = gep_type_begin(GEP);
for (unsigned i = 1; i != Idx; ++i, ++GTI)
  /*skip along*/;

// Compute the offset implied by the rest of the indices.
int64_t Offset = 0;
for (unsigned i = Idx, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
  ConstantInt *OpC = dyn_cast<ConstantInt>(GEP->getOperand(i));
  if (!OpC)
    return None;
  if (OpC->isZero())
    continue; // No offset.

  // Handle struct indices, which add their field offset to the pointer.
  if (StructType *STy = GTI.getStructTypeOrNull()) {
    Offset += DL.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
    continue;
  }

  // Otherwise, we have a sequential type like an array or vector.  Multiply
  // the index by the ElementSize.
  uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
  Offset += Size * OpC->getSExtValue();
}

return Offset;
5741}

5743Optional<int64_t> llvm::isPointerOffset(const Value *Ptr1, const Value *Ptr2,
                                      const DataLayout &DL) {
Ptr1 = Ptr1->stripPointerCasts();
Ptr2 = Ptr2->stripPointerCasts();

// Handle the trivial case first.
if (Ptr1 == Ptr2) {
  return 0;
}

const GEPOperator *GEP1 = dyn_cast<GEPOperator>(Ptr1);
const GEPOperator *GEP2 = dyn_cast<GEPOperator>(Ptr2);

// If one pointer is a GEP and the other isn't, then see if the GEP is a
// constant offset from the base, as in "P" and "gep P, 1".
if (GEP1 && !GEP2 && GEP1->getOperand(0)->stripPointerCasts() == Ptr2) {
  auto Offset = getOffsetFromIndex(GEP1, 1, DL);
  if (!Offset)
    return None;
  return -*Offset;
}

if (GEP2 && !GEP1 && GEP2->getOperand(0)->stripPointerCasts() == Ptr1) {
  return getOffsetFromIndex(GEP2, 1, DL);
}

// Right now we handle the case when Ptr1/Ptr2 are both GEPs with an identical
// base.  After that base, they may have some number of common (and
// potentially variable) indices.  After that they handle some constant
// offset, which determines their offset from each other.  At this point, we
// handle no other case.
if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0))
  return None;

// Skip any common indices and track the GEP types.
unsigned Idx = 1;
for (; Idx != GEP1->getNumOperands() && Idx != GEP2->getNumOperands(); ++Idx)
  if (GEP1->getOperand(Idx) != GEP2->getOperand(Idx))
    break;

auto Offset1 = getOffsetFromIndex(GEP1, Idx, DL);
auto Offset2 = getOffsetFromIndex(GEP2, Idx, DL);
if (!Offset1 || !Offset2)
  return None;
return *Offset2 - *Offset1;
5788}

←

/build/llvm-toolchain-snapshot-10~svn372306/include/llvm/IR/Operator.h

→

1//===-- llvm/Operator.h - Operator utility subclass -------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines various classes for working with Instructions and
10// ConstantExprs.
11//
12//===----------------------------------------------------------------------===//

14#ifndef LLVM_IR_OPERATOR_H
15#define LLVM_IR_OPERATOR_H

17#include "llvm/ADT/None.h"
18#include "llvm/ADT/Optional.h"
19#include "llvm/IR/Constants.h"
20#include "llvm/IR/Instruction.h"
21#include "llvm/IR/Type.h"
22#include "llvm/IR/Value.h"
23#include "llvm/Support/Casting.h"
24#include <cstddef>

26namespace llvm {

28/// This is a utility class that provides an abstraction for the common
29/// functionality between Instructions and ConstantExprs.
30class Operator : public User {
31public:
// The Operator class is intended to be used as a utility, and is never itself
// instantiated.
Operator() = delete;
~Operator() = delete;

void *operator new(size_t s) = delete;

/// Return the opcode for this Instruction or ConstantExpr.
unsigned getOpcode() const {
  if (const Instruction *I2.1
'I' is non-null
1
'I' is non-null
1
'I' is non-null
 = dyn_cast<Instruction>(this))
2
←
Assuming the object is a 'Instruction'→
3
←
Taking true branch→
    return I->getOpcode();
4
←
Returning value, which participates in a condition later→
  return cast<ConstantExpr>(this)->getOpcode();
}

/// If V is an Instruction or ConstantExpr, return its opcode.
/// Otherwise return UserOp1.
static unsigned getOpcode(const Value *V) {
  if (const Instruction *I = dyn_cast<Instruction>(V))
    return I->getOpcode();
  if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
    return CE->getOpcode();
  return Instruction::UserOp1;
}

static bool classof(const Instruction *) { return true; }
static bool classof(const ConstantExpr *) { return true; }
static bool classof(const Value *V) {
  return isa<Instruction>(V) || isa<ConstantExpr>(V);
}
61};

63/// Utility class for integer operators which may exhibit overflow - Add, Sub,
64/// Mul, and Shl. It does not include SDiv, despite that operator having the
65/// potential for overflow.
66class OverflowingBinaryOperator : public Operator {
67public:
enum {
  NoUnsignedWrap = (1 << 0),
  NoSignedWrap   = (1 << 1)
};

73private:
friend class Instruction;
friend class ConstantExpr;

void setHasNoUnsignedWrap(bool B) {
  SubclassOptionalData =
    (SubclassOptionalData & ~NoUnsignedWrap) | (B * NoUnsignedWrap);
}
void setHasNoSignedWrap(bool B) {
  SubclassOptionalData =
    (SubclassOptionalData & ~NoSignedWrap) | (B * NoSignedWrap);
}

86public:
/// Test whether this operation is known to never
/// undergo unsigned overflow, aka the nuw property.
bool hasNoUnsignedWrap() const {
  return SubclassOptionalData & NoUnsignedWrap;
}

/// Test whether this operation is known to never
/// undergo signed overflow, aka the nsw property.
bool hasNoSignedWrap() const {
  return (SubclassOptionalData & NoSignedWrap) != 0;
}

static bool classof(const Instruction *I) {
  return I->getOpcode() == Instruction::Add ||
         I->getOpcode() == Instruction::Sub ||
         I->getOpcode() == Instruction::Mul ||
         I->getOpcode() == Instruction::Shl;
}
static bool classof(const ConstantExpr *CE) {
  return CE->getOpcode() == Instruction::Add ||
         CE->getOpcode() == Instruction::Sub ||
         CE->getOpcode() == Instruction::Mul ||
         CE->getOpcode() == Instruction::Shl;
}
static bool classof(const Value *V) {
  return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||
         (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));
}
115};

117/// A udiv or sdiv instruction, which can be marked as "exact",
118/// indicating that no bits are destroyed.
119class PossiblyExactOperator : public Operator {
120public:
enum {
  IsExact = (1 << 0)
};

125private:
friend class Instruction;
friend class ConstantExpr;

void setIsExact(bool B) {
  SubclassOptionalData = (SubclassOptionalData & ~IsExact) | (B * IsExact);
}

133public:
/// Test whether this division is known to be exact, with zero remainder.
bool isExact() const {
  return SubclassOptionalData & IsExact;
}

static bool isPossiblyExactOpcode(unsigned OpC) {
  return OpC == Instruction::SDiv ||
         OpC == Instruction::UDiv ||
         OpC == Instruction::AShr ||
         OpC == Instruction::LShr;
}

static bool classof(const ConstantExpr *CE) {
  return isPossiblyExactOpcode(CE->getOpcode());
}
static bool classof(const Instruction *I) {
  return isPossiblyExactOpcode(I->getOpcode());
}
static bool classof(const Value *V) {
  return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||
         (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));
}
156};

158/// Convenience struct for specifying and reasoning about fast-math flags.
159class FastMathFlags {
160private:
friend class FPMathOperator;

unsigned Flags = 0;

FastMathFlags(unsigned F) {
  // If all 7 bits are set, turn this into -1. If the number of bits grows,
  // this must be updated. This is intended to provide some forward binary
  // compatibility insurance for the meaning of 'fast' in case bits are added.
  if (F == 0x7F) Flags = ~0U;
  else Flags = F;
}

173public:
// This is how the bits are used in Value::SubclassOptionalData so they
// should fit there too.
// WARNING: We're out of space. SubclassOptionalData only has 7 bits. New
// functionality will require a change in how this information is stored.
enum {
  AllowReassoc    = (1 << 0),
  NoNaNs          = (1 << 1),
  NoInfs          = (1 << 2),
  NoSignedZeros   = (1 << 3),
  AllowReciprocal = (1 << 4),
  AllowContract   = (1 << 5),
  ApproxFunc      = (1 << 6)
};

FastMathFlags() = default;

static FastMathFlags getFast() {
  FastMathFlags FMF;
  FMF.setFast();
  return FMF;
}

bool any() const { return Flags != 0; }
bool none() const { return Flags == 0; }
bool all() const { return Flags == ~0U; }

void clear() { Flags = 0; }
void set()   { Flags = ~0U; }

/// Flag queries
bool allowReassoc() const    { return 0 != (Flags & AllowReassoc); }
bool noNaNs() const          { return 0 != (Flags & NoNaNs); }
bool noInfs() const          { return 0 != (Flags & NoInfs); }
bool noSignedZeros() const   { return 0 != (Flags & NoSignedZeros); }
bool allowReciprocal() const { return 0 != (Flags & AllowReciprocal); }
bool allowContract() const   { return 0 != (Flags & AllowContract); }
bool approxFunc() const      { return 0 != (Flags & ApproxFunc); }
/// 'Fast' means all bits are set.
bool isFast() const          { return all(); }

/// Flag setters
void setAllowReassoc(bool B = true) {
  Flags = (Flags & ~AllowReassoc) | B * AllowReassoc;
}
void setNoNaNs(bool B = true) {
  Flags = (Flags & ~NoNaNs) | B * NoNaNs;
}
void setNoInfs(bool B = true) {
  Flags = (Flags & ~NoInfs) | B * NoInfs;
}
void setNoSignedZeros(bool B = true) {
  Flags = (Flags & ~NoSignedZeros) | B * NoSignedZeros;
}
void setAllowReciprocal(bool B = true) {
  Flags = (Flags & ~AllowReciprocal) | B * AllowReciprocal;
}
void setAllowContract(bool B = true) {
  Flags = (Flags & ~AllowContract) | B * AllowContract;
}
void setApproxFunc(bool B = true) {
  Flags = (Flags & ~ApproxFunc) | B * ApproxFunc;
}
void setFast(bool B = true) { B ? set() : clear(); }

void operator&=(const FastMathFlags &OtherFlags) {
  Flags &= OtherFlags.Flags;
}
241};

243/// Utility class for floating point operations which can have
244/// information about relaxed accuracy requirements attached to them.
245class FPMathOperator : public Operator {
246private:
friend class Instruction;

/// 'Fast' means all bits are set.
void setFast(bool B) {
  setHasAllowReassoc(B);
  setHasNoNaNs(B);
  setHasNoInfs(B);
  setHasNoSignedZeros(B);
  setHasAllowReciprocal(B);
  setHasAllowContract(B);
  setHasApproxFunc(B);
}

void setHasAllowReassoc(bool B) {
  SubclassOptionalData =
  (SubclassOptionalData & ~FastMathFlags::AllowReassoc) |
  (B * FastMathFlags::AllowReassoc);
}

void setHasNoNaNs(bool B) {
  SubclassOptionalData =
    (SubclassOptionalData & ~FastMathFlags::NoNaNs) |
    (B * FastMathFlags::NoNaNs);
}

void setHasNoInfs(bool B) {
  SubclassOptionalData =
    (SubclassOptionalData & ~FastMathFlags::NoInfs) |
    (B * FastMathFlags::NoInfs);
}

void setHasNoSignedZeros(bool B) {
  SubclassOptionalData =
    (SubclassOptionalData & ~FastMathFlags::NoSignedZeros) |
    (B * FastMathFlags::NoSignedZeros);
}

void setHasAllowReciprocal(bool B) {
  SubclassOptionalData =
    (SubclassOptionalData & ~FastMathFlags::AllowReciprocal) |
    (B * FastMathFlags::AllowReciprocal);
}

void setHasAllowContract(bool B) {
  SubclassOptionalData =
      (SubclassOptionalData & ~FastMathFlags::AllowContract) |
      (B * FastMathFlags::AllowContract);
}

void setHasApproxFunc(bool B) {
  SubclassOptionalData =
      (SubclassOptionalData & ~FastMathFlags::ApproxFunc) |
      (B * FastMathFlags::ApproxFunc);
}

/// Convenience function for setting multiple fast-math flags.
/// FMF is a mask of the bits to set.
void setFastMathFlags(FastMathFlags FMF) {
  SubclassOptionalData |= FMF.Flags;
}

/// Convenience function for copying all fast-math flags.
/// All values in FMF are transferred to this operator.
void copyFastMathFlags(FastMathFlags FMF) {
  SubclassOptionalData = FMF.Flags;
}

314public:
/// Test if this operation allows all non-strict floating-point transforms.
bool isFast() const {
  return ((SubclassOptionalData & FastMathFlags::AllowReassoc) != 0 &&
          (SubclassOptionalData & FastMathFlags::NoNaNs) != 0 &&
          (SubclassOptionalData & FastMathFlags::NoInfs) != 0 &&
          (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0 &&
          (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0 &&
          (SubclassOptionalData & FastMathFlags::AllowContract) != 0 &&
          (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0);
}

/// Test if this operation may be simplified with reassociative transforms.
bool hasAllowReassoc() const {
  return (SubclassOptionalData & FastMathFlags::AllowReassoc) != 0;
}

/// Test if this operation's arguments and results are assumed not-NaN.
bool hasNoNaNs() const {
  return (SubclassOptionalData & FastMathFlags::NoNaNs) != 0;
}

/// Test if this operation's arguments and results are assumed not-infinite.
bool hasNoInfs() const {
  return (SubclassOptionalData & FastMathFlags::NoInfs) != 0;
}

/// Test if this operation can ignore the sign of zero.
bool hasNoSignedZeros() const {
  return (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0;
}

/// Test if this operation can use reciprocal multiply instead of division.
bool hasAllowReciprocal() const {
  return (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0;
}

/// Test if this operation can be floating-point contracted (FMA).
bool hasAllowContract() const {
  return (SubclassOptionalData & FastMathFlags::AllowContract) != 0;
}

/// Test if this operation allows approximations of math library functions or
/// intrinsics.
bool hasApproxFunc() const {
  return (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0;
}

/// Convenience function for getting all the fast-math flags
FastMathFlags getFastMathFlags() const {
  return FastMathFlags(SubclassOptionalData);
}

/// Get the maximum error permitted by this operation in ULPs. An accuracy of
/// 0.0 means that the operation should be performed with the default
/// precision.
float getFPAccuracy() const;

static bool classof(const Value *V) {
  unsigned Opcode;
  if (auto *I = dyn_cast<Instruction>(V))
    Opcode = I->getOpcode();
  else if (auto *CE = dyn_cast<ConstantExpr>(V))
    Opcode = CE->getOpcode();
  else
    return false;

  switch (Opcode) {
  case Instruction::FCmp:
    return true;
  // non math FP Operators (no FMF)
  case Instruction::ExtractElement:
  case Instruction::ShuffleVector:
  case Instruction::InsertElement:
  case Instruction::PHI:
    return false;
  default:
    return V->getType()->isFPOrFPVectorTy();
  }
}
394};

396/// A helper template for defining operators for individual opcodes.
397template<typename SuperClass, unsigned Opc>
398class ConcreteOperator : public SuperClass {
399public:
static bool classof(const Instruction *I) {
  return I->getOpcode() == Opc;
}
static bool classof(const ConstantExpr *CE) {
  return CE->getOpcode() == Opc;
}
static bool classof(const Value *V) {
  return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||
         (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));
}
410};

412class AddOperator
: public ConcreteOperator<OverflowingBinaryOperator, Instruction::Add> {
414};
415class SubOperator
: public ConcreteOperator<OverflowingBinaryOperator, Instruction::Sub> {
417};
418class MulOperator
: public ConcreteOperator<OverflowingBinaryOperator, Instruction::Mul> {
420};
421class ShlOperator
: public ConcreteOperator<OverflowingBinaryOperator, Instruction::Shl> {
423};

425class SDivOperator
: public ConcreteOperator<PossiblyExactOperator, Instruction::SDiv> {
427};
428class UDivOperator
: public ConcreteOperator<PossiblyExactOperator, Instruction::UDiv> {
430};
431class AShrOperator
: public ConcreteOperator<PossiblyExactOperator, Instruction::AShr> {
433};
434class LShrOperator
: public ConcreteOperator<PossiblyExactOperator, Instruction::LShr> {
436};

438class ZExtOperator : public ConcreteOperator<Operator, Instruction::ZExt> {};

440class GEPOperator
: public ConcreteOperator<Operator, Instruction::GetElementPtr> {
friend class GetElementPtrInst;
friend class ConstantExpr;

enum {
  IsInBounds = (1 << 0),
  // InRangeIndex: bits 1-6
};

void setIsInBounds(bool B) {
  SubclassOptionalData =
    (SubclassOptionalData & ~IsInBounds) | (B * IsInBounds);
}

455public:
/// Test whether this is an inbounds GEP, as defined by LangRef.html.
bool isInBounds() const {
  return SubclassOptionalData & IsInBounds;
}

/// Returns the offset of the index with an inrange attachment, or None if
/// none.
Optional<unsigned> getInRangeIndex() const {
  if (SubclassOptionalData >> 1 == 0) return None;
  return (SubclassOptionalData >> 1) - 1;
}

inline op_iterator       idx_begin()       { return op_begin()+1; }
inline const_op_iterator idx_begin() const { return op_begin()+1; }
inline op_iterator       idx_end()         { return op_end(); }
inline const_op_iterator idx_end()   const { return op_end(); }

Value *getPointerOperand() {
  return getOperand(0);
}
const Value *getPointerOperand() const {
  return getOperand(0);
}
static unsigned getPointerOperandIndex() {
  return 0U;                      // get index for modifying correct operand
}

/// Method to return the pointer operand as a PointerType.
Type *getPointerOperandType() const {
  return getPointerOperand()->getType();
}

Type *getSourceElementType() const;
Type *getResultElementType() const;

/// Method to return the address space of the pointer operand.
unsigned getPointerAddressSpace() const {
  return getPointerOperandType()->getPointerAddressSpace();
}

unsigned getNumIndices() const {  // Note: always non-negative
  return getNumOperands() - 1;
}

bool hasIndices() const {
  return getNumOperands() > 1;
}

/// Return true if all of the indices of this GEP are zeros.
/// If so, the result pointer and the first operand have the same
/// value, just potentially different types.
bool hasAllZeroIndices() const {
  for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) {
    if (ConstantInt *C = dyn_cast<ConstantInt>(I))
      if (C->isZero())
        continue;
    return false;
  }
  return true;
}

/// Return true if all of the indices of this GEP are constant integers.
/// If so, the result pointer and the first operand have
/// a constant offset between them.
bool hasAllConstantIndices() const {
  for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) {
    if (!isa<ConstantInt>(I))
      return false;
  }
  return true;
}

unsigned countNonConstantIndices() const {
  return count_if(make_range(idx_begin(), idx_end()), [](const Use& use) {
      return !isa<ConstantInt>(*use);
    });
}

/// Accumulate the constant address offset of this GEP if possible.
///
/// This routine accepts an APInt into which it will accumulate the constant
/// offset of this GEP if the GEP is in fact constant. If the GEP is not
/// all-constant, it returns false and the value of the offset APInt is
/// undefined (it is *not* preserved!). The APInt passed into this routine
/// must be at exactly as wide as the IntPtr type for the address space of the
/// base GEP pointer.
bool accumulateConstantOffset(const DataLayout &DL, APInt &Offset) const;
543};

545class PtrToIntOperator
  : public ConcreteOperator<Operator, Instruction::PtrToInt> {
friend class PtrToInt;
friend class ConstantExpr;

550public:
Value *getPointerOperand() {
  return getOperand(0);
}
const Value *getPointerOperand() const {
  return getOperand(0);
}

static unsigned getPointerOperandIndex() {
  return 0U;                      // get index for modifying correct operand
}

/// Method to return the pointer operand as a PointerType.
Type *getPointerOperandType() const {
  return getPointerOperand()->getType();
}

/// Method to return the address space of the pointer operand.
unsigned getPointerAddressSpace() const {
  return cast<PointerType>(getPointerOperandType())->getAddressSpace();
}
571};

573class BitCastOperator
  : public ConcreteOperator<Operator, Instruction::BitCast> {
friend class BitCastInst;
friend class ConstantExpr;

578public:
Type *getSrcTy() const {
  return getOperand(0)->getType();
}

Type *getDestTy() const {
  return getType();
}
586};

588} // end namespace llvm

590#endif // LLVM_IR_OPERATOR_H

←

/build/llvm-toolchain-snapshot-10~svn372306/include/llvm/Analysis/ValueTracking.h

1//===- llvm/Analysis/ValueTracking.h - Walk computations --------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains routines that help analyze properties that chains of
10// computations have.
11//
12//===----------------------------------------------------------------------===//

14#ifndef LLVM_ANALYSIS_VALUETRACKING_H
15#define LLVM_ANALYSIS_VALUETRACKING_H

17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/Optional.h"
19#include "llvm/ADT/SmallSet.h"
20#include "llvm/IR/CallSite.h"
21#include "llvm/IR/Constants.h"
22#include "llvm/IR/DataLayout.h"
23#include "llvm/IR/Instruction.h"
24#include "llvm/IR/Intrinsics.h"
25#include <cassert>
26#include <cstdint>

28namespace llvm {

30class AddOperator;
31class APInt;
32class AssumptionCache;
33class DominatorTree;
34class GEPOperator;
35class IntrinsicInst;
36class WithOverflowInst;
37struct KnownBits;
38class Loop;
39class LoopInfo;
40class MDNode;
41class OptimizationRemarkEmitter;
42class StringRef;
43class TargetLibraryInfo;
44class Value;

/// Determine which bits of V are known to be either zero or one and return
/// them in the KnownZero/KnownOne bit sets.
///
/// This function is defined on values with integer type, values with pointer
/// type, and vectors of integers.  In the case
/// where V is a vector, the known zero and known one values are the
/// same width as the vector element, and the bit is set only if it is true
/// for all of the elements in the vector.
void computeKnownBits(const Value *V, KnownBits &Known,
                      const DataLayout &DL, unsigned Depth = 0,
                      AssumptionCache *AC = nullptr,
                      const Instruction *CxtI = nullptr,
                      const DominatorTree *DT = nullptr,
                      OptimizationRemarkEmitter *ORE = nullptr,
                      bool UseInstrInfo = true);

/// Returns the known bits rather than passing by reference.
KnownBits computeKnownBits(const Value *V, const DataLayout &DL,
                           unsigned Depth = 0, AssumptionCache *AC = nullptr,
                           const Instruction *CxtI = nullptr,
                           const DominatorTree *DT = nullptr,
                           OptimizationRemarkEmitter *ORE = nullptr,
                           bool UseInstrInfo = true);

/// Compute known bits from the range metadata.
/// \p KnownZero the set of bits that are known to be zero
/// \p KnownOne the set of bits that are known to be one
void computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
                                       KnownBits &Known);

/// Return true if LHS and RHS have no common bits set.
bool haveNoCommonBitsSet(const Value *LHS, const Value *RHS,
                         const DataLayout &DL,
                         AssumptionCache *AC = nullptr,
                         const Instruction *CxtI = nullptr,
                         const DominatorTree *DT = nullptr,
                         bool UseInstrInfo = true);

/// Return true if the given value is known to have exactly one bit set when
/// defined. For vectors return true if every element is known to be a power
/// of two when defined. Supports values with integer or pointer type and
/// vectors of integers. If 'OrZero' is set, then return true if the given
/// value is either a power of two or zero.
bool isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL,
                            bool OrZero = false, unsigned Depth = 0,
                            AssumptionCache *AC = nullptr,
                            const Instruction *CxtI = nullptr,
                            const DominatorTree *DT = nullptr,
                            bool UseInstrInfo = true);

bool isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI);

/// Return true if the given value is known to be non-zero when defined. For
/// vectors, return true if every element is known to be non-zero when
/// defined. For pointers, if the context instruction and dominator tree are
/// specified, perform context-sensitive analysis and return true if the
/// pointer couldn't possibly be null at the specified instruction.
/// Supports values with integer or pointer type and vectors of integers.
bool isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth = 0,
                    AssumptionCache *AC = nullptr,
                    const Instruction *CxtI = nullptr,
                    const DominatorTree *DT = nullptr,
                    bool UseInstrInfo = true);

/// Return true if the two given values are negation.
/// Currently can recoginze Value pair:
/// 1: <X, Y> if X = sub (0, Y) or Y = sub (0, X)
/// 2: <X, Y> if X = sub (A, B) and Y = sub (B, A)
bool isKnownNegation(const Value *X, const Value *Y, bool NeedNSW = false);

/// Returns true if the give value is known to be non-negative.
bool isKnownNonNegative(const Value *V, const DataLayout &DL,
                        unsigned Depth = 0,
                        AssumptionCache *AC = nullptr,
                        const Instruction *CxtI = nullptr,
                        const DominatorTree *DT = nullptr,
                        bool UseInstrInfo = true);

/// Returns true if the given value is known be positive (i.e. non-negative
/// and non-zero).
bool isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth = 0,
                     AssumptionCache *AC = nullptr,
                     const Instruction *CxtI = nullptr,
                     const DominatorTree *DT = nullptr,
                     bool UseInstrInfo = true);

/// Returns true if the given value is known be negative (i.e. non-positive
/// and non-zero).
bool isKnownNegative(const Value *V, const DataLayout &DL, unsigned Depth = 0,
                     AssumptionCache *AC = nullptr,
                     const Instruction *CxtI = nullptr,
                     const DominatorTree *DT = nullptr,
                     bool UseInstrInfo = true);

/// Return true if the given values are known to be non-equal when defined.
/// Supports scalar integer types only.
bool isKnownNonEqual(const Value *V1, const Value *V2, const DataLayout &DL,
                     AssumptionCache *AC = nullptr,
                     const Instruction *CxtI = nullptr,
                     const DominatorTree *DT = nullptr,
                     bool UseInstrInfo = true);

/// Return true if 'V & Mask' is known to be zero. We use this predicate to
/// simplify operations downstream. Mask is known to be zero for bits that V
/// cannot have.
///
/// This function is defined on values with integer type, values with pointer
/// type, and vectors of integers.  In the case
/// where V is a vector, the mask, known zero, and known one values are the
/// same width as the vector element, and the bit is set only if it is true
/// for all of the elements in the vector.
bool MaskedValueIsZero(const Value *V, const APInt &Mask,
                       const DataLayout &DL,
                       unsigned Depth = 0, AssumptionCache *AC = nullptr,
                       const Instruction *CxtI = nullptr,
                       const DominatorTree *DT = nullptr,
                       bool UseInstrInfo = true);

/// Return the number of times the sign bit of the register is replicated into
/// the other bits. We know that at least 1 bit is always equal to the sign
/// bit (itself), but other cases can give us information. For example,
/// immediately after an "ashr X, 2", we know that the top 3 bits are all
/// equal to each other, so we return 3. For vectors, return the number of
/// sign bits for the vector element with the mininum number of known sign
/// bits.
unsigned ComputeNumSignBits(const Value *Op, const DataLayout &DL,
                            unsigned Depth = 0, AssumptionCache *AC = nullptr,
                            const Instruction *CxtI = nullptr,
                            const DominatorTree *DT = nullptr,
                            bool UseInstrInfo = true);

/// This function computes the integer multiple of Base that equals V. If
/// successful, it returns true and returns the multiple in Multiple. If
/// unsuccessful, it returns false. Also, if V can be simplified to an
/// integer, then the simplified V is returned in Val. Look through sext only
/// if LookThroughSExt=true.
bool ComputeMultiple(Value *V, unsigned Base, Value *&Multiple,
                     bool LookThroughSExt = false,
                     unsigned Depth = 0);

/// Map a call instruction to an intrinsic ID.  Libcalls which have equivalent
/// intrinsics are treated as-if they were intrinsics.
Intrinsic::ID getIntrinsicForCallSite(ImmutableCallSite ICS,
                                      const TargetLibraryInfo *TLI);

/// Return true if we can prove that the specified FP value is never equal to
/// -0.0.
bool CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI,
                          unsigned Depth = 0);

/// Return true if we can prove that the specified FP value is either NaN or
/// never less than -0.0.
///
///      NaN --> true
///       +0 --> true
///       -0 --> true
///   x > +0 --> true
///   x < -0 --> false
bool CannotBeOrderedLessThanZero(const Value *V, const TargetLibraryInfo *TLI);

/// Return true if the floating-point scalar value is not a NaN or if the
/// floating-point vector value has no NaN elements. Return false if a value
/// could ever be NaN.
bool isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI,
                     unsigned Depth = 0);

/// Return true if we can prove that the specified FP value's sign bit is 0.
///
///      NaN --> true/false (depending on the NaN's sign bit)
///       +0 --> true
///       -0 --> false
///   x > +0 --> true
///   x < -0 --> false
bool SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI);

/// If the specified value can be set by repeating the same byte in memory,
/// return the i8 value that it is represented with. This is true for all i8
/// values obviously, but is also true for i32 0, i32 -1, i16 0xF0F0, double
/// 0.0 etc. If the value can't be handled with a repeated byte store (e.g.
/// i16 0x1234), return null. If the value is entirely undef and padding,
/// return undef.
Value *isBytewiseValue(Value *V, const DataLayout &DL);

/// Given an aggregrate and an sequence of indices, see if the scalar value
/// indexed is already around as a register, for example if it were inserted
/// directly into the aggregrate.
///
/// If InsertBefore is not null, this function will duplicate (modified)
/// insertvalues when a part of a nested struct is extracted.
Value *FindInsertedValue(Value *V,
                         ArrayRef<unsigned> idx_range,
                         Instruction *InsertBefore = nullptr);

/// Analyze the specified pointer to see if it can be expressed as a base
/// pointer plus a constant offset. Return the base and offset to the caller.
///
/// This is a wrapper around Value::stripAndAccumulateConstantOffsets that
/// creates and later unpacks the required APInt.
inline Value *GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
                                               const DataLayout &DL,
                                               bool AllowNonInbounds = true) {
  APInt OffsetAPInt(DL.getIndexTypeSizeInBits(Ptr->getType()), 0);
  Value *Base =
      Ptr->stripAndAccumulateConstantOffsets(DL, OffsetAPInt, AllowNonInbounds);

  Offset = OffsetAPInt.getSExtValue();
  return Base;
}
inline const Value *
GetPointerBaseWithConstantOffset(const Value *Ptr, int64_t &Offset,
                                 const DataLayout &DL,
                                 bool AllowNonInbounds = true) {
  return GetPointerBaseWithConstantOffset(const_cast<Value *>(Ptr), Offset, DL,
                                          AllowNonInbounds);
}

/// Returns true if the GEP is based on a pointer to a string (array of
// \p CharSize integers) and is indexing into this string.
bool isGEPBasedOnPointerToString(const GEPOperator *GEP,
                                 unsigned CharSize = 8);

/// Represents offset+length into a ConstantDataArray.
struct ConstantDataArraySlice {
  /// ConstantDataArray pointer. nullptr indicates a zeroinitializer (a valid
  /// initializer, it just doesn't fit the ConstantDataArray interface).
  const ConstantDataArray *Array;

  /// Slice starts at this Offset.
  uint64_t Offset;

  /// Length of the slice.
  uint64_t Length;

  /// Moves the Offset and adjusts Length accordingly.
  void move(uint64_t Delta) {
    assert(Delta < Length)((Delta < Length) ? static_cast<void> (0) : __assert_fail
 ("Delta < Length", "/build/llvm-toolchain-snapshot-10~svn372306/include/llvm/Analysis/ValueTracking.h"
, 281, __PRETTY_FUNCTION__));
    Offset += Delta;
    Length -= Delta;
  }

  /// Convenience accessor for elements in the slice.
  uint64_t operator[](unsigned I) const {
    return Array==nullptr ? 0 : Array->getElementAsInteger(I + Offset);
  }
};

/// Returns true if the value \p V is a pointer into a ConstantDataArray.
/// If successful \p Slice will point to a ConstantDataArray info object
/// with an appropriate offset.
bool getConstantDataArrayInfo(const Value *V, ConstantDataArraySlice &Slice,
                              unsigned ElementSize, uint64_t Offset = 0);

/// This function computes the length of a null-terminated C string pointed to
/// by V. If successful, it returns true and returns the string in Str. If
/// unsuccessful, it returns false. This does not include the trailing null
/// character by default. If TrimAtNul is set to false, then this returns any
/// trailing null characters as well as any other characters that come after
/// it.
bool getConstantStringInfo(const Value *V, StringRef &Str,
                           uint64_t Offset = 0, bool TrimAtNul = true);

/// If we can compute the length of the string pointed to by the specified
/// pointer, return 'len+1'.  If we can't, return 0.
uint64_t GetStringLength(const Value *V, unsigned CharSize = 8);

/// This function returns call pointer argument that is considered the same by
/// aliasing rules. You CAN'T use it to replace one value with another. If
/// \p MustPreserveNullness is true, the call must preserve the nullness of
/// the pointer.
const Value *getArgumentAliasingToReturnedPointer(const CallBase *Call,
                                                  bool MustPreserveNullness);
inline Value *
getArgumentAliasingToReturnedPointer(CallBase *Call,
                                     bool MustPreserveNullness) {
  return const_cast<Value *>(getArgumentAliasingToReturnedPointer(
      const_cast<const CallBase *>(Call), MustPreserveNullness));
}

/// {launder,strip}.invariant.group returns pointer that aliases its argument,
/// and it only captures pointer by returning it.
/// These intrinsics are not marked as nocapture, because returning is
/// considered as capture. The arguments are not marked as returned neither,
/// because it would make it useless. If \p MustPreserveNullness is true,
/// the intrinsic must preserve the nullness of the pointer.
bool isIntrinsicReturningPointerAliasingArgumentWithoutCapturing(
    const CallBase *Call, bool MustPreserveNullness);

/// This method strips off any GEP address adjustments and pointer casts from
/// the specified value, returning the original object being addressed. Note
/// that the returned value has pointer type if the specified value does. If
/// the MaxLookup value is non-zero, it limits the number of instructions to
/// be stripped off.
Value *GetUnderlyingObject(Value *V, const DataLayout &DL,
                           unsigned MaxLookup = 6);
inline const Value *GetUnderlyingObject(const Value *V, const DataLayout &DL,
                                        unsigned MaxLookup = 6) {
  return GetUnderlyingObject(const_cast<Value *>(V), DL, MaxLookup);
}

/// This method is similar to GetUnderlyingObject except that it can
/// look through phi and select instructions and return multiple objects.
///
/// If LoopInfo is passed, loop phis are further analyzed.  If a pointer
/// accesses different objects in each iteration, we don't look through the
/// phi node. E.g. consider this loop nest:
///
///   int **A;
///   for (i)
///     for (j) {
///        A[i][j] = A[i-1][j] * B[j]
///     }
///
/// This is transformed by Load-PRE to stash away A[i] for the next iteration
/// of the outer loop:
///
///   Curr = A[0];          // Prev_0
///   for (i: 1..N) {
///     Prev = Curr;        // Prev = PHI (Prev_0, Curr)
///     Curr = A[i];
///     for (j: 0..N) {
///        Curr[j] = Prev[j] * B[j]
///     }
///   }
///
/// Since A[i] and A[i-1] are independent pointers, getUnderlyingObjects
/// should not assume that Curr and Prev share the same underlying object thus
/// it shouldn't look through the phi above.
void GetUnderlyingObjects(const Value *V,
                          SmallVectorImpl<const Value *> &Objects,
                          const DataLayout &DL, LoopInfo *LI = nullptr,
                          unsigned MaxLookup = 6);

/// This is a wrapper around GetUnderlyingObjects and adds support for basic
/// ptrtoint+arithmetic+inttoptr sequences.
bool getUnderlyingObjectsForCodeGen(const Value *V,
                          SmallVectorImpl<Value *> &Objects,
                          const DataLayout &DL);

/// Return true if the only users of this pointer are lifetime markers.
bool onlyUsedByLifetimeMarkers(const Value *V);

/// Return true if speculation of the given load must be suppressed to avoid
/// ordering or interfering with an active sanitizer.  If not suppressed,
/// dereferenceability and alignment must be proven separately.  Note: This
/// is only needed for raw reasoning; if you use the interface below
/// (isSafeToSpeculativelyExecute), this is handled internally.
bool mustSuppressSpeculation(const LoadInst &LI);

/// Return true if the instruction does not have any effects besides
/// calculating the result and does not have undefined behavior.
///
/// This method never returns true for an instruction that returns true for
/// mayHaveSideEffects; however, this method also does some other checks in
/// addition. It checks for undefined behavior, like dividing by zero or
/// loading from an invalid pointer (but not for undefined results, like a
/// shift with a shift amount larger than the width of the result). It checks
/// for malloc and alloca because speculatively executing them might cause a
/// memory leak. It also returns false for instructions related to control
/// flow, specifically terminators and PHI nodes.
///
/// If the CtxI is specified this method performs context-sensitive analysis
/// and returns true if it is safe to execute the instruction immediately
/// before the CtxI.
///
/// If the CtxI is NOT specified this method only looks at the instruction
/// itself and its operands, so if this method returns true, it is safe to
/// move the instruction as long as the correct dominance relationships for
/// the operands and users hold.
///
/// This method can return true for instructions that read memory;
/// for such instructions, moving them may change the resulting value.
bool isSafeToSpeculativelyExecute(const Value *V,
                                  const Instruction *CtxI = nullptr,
                                  const DominatorTree *DT = nullptr);

/// Returns true if the result or effects of the given instructions \p I
/// depend on or influence global memory.
/// Memory dependence arises for example if the instruction reads from
/// memory or may produce effects or undefined behaviour. Memory dependent
/// instructions generally cannot be reorderd with respect to other memory
/// dependent instructions or moved into non-dominated basic blocks.
/// Instructions which just compute a value based on the values of their
/// operands are not memory dependent.
bool mayBeMemoryDependent(const Instruction &I);

/// Return true if it is an intrinsic that cannot be speculated but also
/// cannot trap.
bool isAssumeLikeIntrinsic(const Instruction *I);

/// Return true if it is valid to use the assumptions provided by an
/// assume intrinsic, I, at the point in the control-flow identified by the
/// context instruction, CxtI.
bool isValidAssumeForContext(const Instruction *I, const Instruction *CxtI,
                             const DominatorTree *DT = nullptr);

enum class OverflowResult {
  /// Always overflows in the direction of signed/unsigned min value.
  AlwaysOverflowsLow,
  /// Always overflows in the direction of signed/unsigned max value.
  AlwaysOverflowsHigh,
  /// May or may not overflow.
  MayOverflow,
  /// Never overflows.
  NeverOverflows,
};

OverflowResult computeOverflowForUnsignedMul(const Value *LHS,
                                             const Value *RHS,
                                             const DataLayout &DL,
                                             AssumptionCache *AC,
                                             const Instruction *CxtI,
                                             const DominatorTree *DT,
                                             bool UseInstrInfo = true);
OverflowResult computeOverflowForSignedMul(const Value *LHS, const Value *RHS,
                                           const DataLayout &DL,
                                           AssumptionCache *AC,
                                           const Instruction *CxtI,
                                           const DominatorTree *DT,
                                           bool UseInstrInfo = true);
OverflowResult computeOverflowForUnsignedAdd(const Value *LHS,
                                             const Value *RHS,
                                             const DataLayout &DL,
                                             AssumptionCache *AC,
                                             const Instruction *CxtI,
                                             const DominatorTree *DT,
                                             bool UseInstrInfo = true);
OverflowResult computeOverflowForSignedAdd(const Value *LHS, const Value *RHS,
                                           const DataLayout &DL,
                                           AssumptionCache *AC = nullptr,
                                           const Instruction *CxtI = nullptr,
                                           const DominatorTree *DT = nullptr);
/// This version also leverages the sign bit of Add if known.
OverflowResult computeOverflowForSignedAdd(const AddOperator *Add,
                                           const DataLayout &DL,
                                           AssumptionCache *AC = nullptr,
                                           const Instruction *CxtI = nullptr,
                                           const DominatorTree *DT = nullptr);
OverflowResult computeOverflowForUnsignedSub(const Value *LHS, const Value *RHS,
                                             const DataLayout &DL,
                                             AssumptionCache *AC,
                                             const Instruction *CxtI,
                                             const DominatorTree *DT);
OverflowResult computeOverflowForSignedSub(const Value *LHS, const Value *RHS,
                                           const DataLayout &DL,
                                           AssumptionCache *AC,
                                           const Instruction *CxtI,
                                           const DominatorTree *DT);

/// Returns true if the arithmetic part of the \p WO 's result is
/// used only along the paths control dependent on the computation
/// not overflowing, \p WO being an <op>.with.overflow intrinsic.
bool isOverflowIntrinsicNoWrap(const WithOverflowInst *WO,
                               const DominatorTree &DT);


/// Determine the possible constant range of an integer or vector of integer
/// value. This is intended as a cheap, non-recursive check.
ConstantRange computeConstantRange(const Value *V, bool UseInstrInfo = true);

/// Return true if this function can prove that the instruction I will
/// always transfer execution to one of its successors (including the next
/// instruction that follows within a basic block). E.g. this is not
/// guaranteed for function calls that could loop infinitely.
///
/// In other words, this function returns false for instructions that may
/// transfer execution or fail to transfer execution in a way that is not
/// captured in the CFG nor in the sequence of instructions within a basic
/// block.
///
/// Undefined behavior is assumed not to happen, so e.g. division is
/// guaranteed to transfer execution to the following instruction even
/// though division by zero might cause undefined behavior.
bool isGuaranteedToTransferExecutionToSuccessor(const Instruction *I);

/// Returns true if this block does not contain a potential implicit exit.
/// This is equivelent to saying that all instructions within the basic block
/// are guaranteed to transfer execution to their successor within the basic
/// block. This has the same assumptions w.r.t. undefined behavior as the
/// instruction variant of this function.
bool isGuaranteedToTransferExecutionToSuccessor(const BasicBlock *BB);

/// Return true if this function can prove that the instruction I
/// is executed for every iteration of the loop L.
///
/// Note that this currently only considers the loop header.
bool isGuaranteedToExecuteForEveryIteration(const Instruction *I,
                                            const Loop *L);

/// Return true if this function can prove that I is guaranteed to yield
/// full-poison (all bits poison) if at least one of its operands are
/// full-poison (all bits poison).
///
/// The exact rules for how poison propagates through instructions have
/// not been settled as of 2015-07-10, so this function is conservative
/// and only considers poison to be propagated in uncontroversial
/// cases. There is no attempt to track values that may be only partially
/// poison.
bool propagatesFullPoison(const Instruction *I);

/// Return either nullptr or an operand of I such that I will trigger
/// undefined behavior if I is executed and that operand has a full-poison
/// value (all bits poison).
const Value *getGuaranteedNonFullPoisonOp(const Instruction *I);

/// Return true if the given instruction must trigger undefined behavior.
/// when I is executed with any operands which appear in KnownPoison holding
/// a full-poison value at the point of execution.
bool mustTriggerUB(const Instruction *I,
                   const SmallSet<const Value *, 16>& KnownPoison);

/// Return true if this function can prove that if PoisonI is executed
/// and yields a full-poison value (all bits poison), then that will
/// trigger undefined behavior.
///
/// Note that this currently only considers the basic block that is
/// the parent of I.
bool programUndefinedIfFullPoison(const Instruction *PoisonI);

/// Specific patterns of select instructions we can match.
enum SelectPatternFlavor {
  SPF_UNKNOWN = 0,
  SPF_SMIN,                   /// Signed minimum
  SPF_UMIN,                   /// Unsigned minimum
  SPF_SMAX,                   /// Signed maximum
  SPF_UMAX,                   /// Unsigned maximum
  SPF_FMINNUM,                /// Floating point minnum
  SPF_FMAXNUM,                /// Floating point maxnum
  SPF_ABS,                    /// Absolute value
  SPF_NABS                    /// Negated absolute value
};

/// Behavior when a floating point min/max is given one NaN and one
/// non-NaN as input.
enum SelectPatternNaNBehavior {
  SPNB_NA = 0,                /// NaN behavior not applicable.
  SPNB_RETURNS_NAN,           /// Given one NaN input, returns the NaN.
  SPNB_RETURNS_OTHER,         /// Given one NaN input, returns the non-NaN.
  SPNB_RETURNS_ANY            /// Given one NaN input, can return either (or
                              /// it has been determined that no operands can
                              /// be NaN).
};

struct SelectPatternResult {
  SelectPatternFlavor Flavor;
  SelectPatternNaNBehavior NaNBehavior; /// Only applicable if Flavor is
                                        /// SPF_FMINNUM or SPF_FMAXNUM.
  bool Ordered;               /// When implementing this min/max pattern as
                              /// fcmp; select, does the fcmp have to be
                              /// ordered?

  /// Return true if \p SPF is a min or a max pattern.
  static bool isMinOrMax(SelectPatternFlavor SPF) {
    return SPF != SPF_UNKNOWN && SPF != SPF_ABS && SPF != SPF_NABS;
  }
};

/// Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind
/// and providing the out parameter results if we successfully match.
///
/// For ABS/NABS, LHS will be set to the input to the abs idiom. RHS will be
/// the negation instruction from the idiom.
///
/// If CastOp is not nullptr, also match MIN/MAX idioms where the type does
/// not match that of the original select. If this is the case, the cast
/// operation (one of Trunc,SExt,Zext) that must be done to transform the
/// type of LHS and RHS into the type of V is returned in CastOp.
///
/// For example:
///   %1 = icmp slt i32 %a, i32 4
///   %2 = sext i32 %a to i64
///   %3 = select i1 %1, i64 %2, i64 4
///
/// -> LHS = %a, RHS = i32 4, *CastOp = Instruction::SExt
///
SelectPatternResult matchSelectPattern(Value *V, Value *&LHS, Value *&RHS,
                                       Instruction::CastOps *CastOp = nullptr,
                                       unsigned Depth = 0);
inline SelectPatternResult
matchSelectPattern(const Value *V, const Value *&LHS, const Value *&RHS,
                   Instruction::CastOps *CastOp = nullptr) {
  Value *L = const_cast<Value*>(LHS);
10
←
Assigned value is garbage or undefined
  Value *R = const_cast<Value*>(RHS);
  auto Result = matchSelectPattern(const_cast<Value*>(V), L, R);
  LHS = L;
  RHS = R;
  return Result;
}

/// Determine the pattern that a select with the given compare as its
/// predicate and given values as its true/false operands would match.
SelectPatternResult matchDecomposedSelectPattern(
    CmpInst *CmpI, Value *TrueVal, Value *FalseVal, Value *&LHS, Value *&RHS,
    Instruction::CastOps *CastOp = nullptr, unsigned Depth = 0);

/// Return the canonical comparison predicate for the specified
/// minimum/maximum flavor.
CmpInst::Predicate getMinMaxPred(SelectPatternFlavor SPF,
                                 bool Ordered = false);

/// Return the inverse minimum/maximum flavor of the specified flavor.
/// For example, signed minimum is the inverse of signed maximum.
SelectPatternFlavor getInverseMinMaxFlavor(SelectPatternFlavor SPF);

/// Return the canonical inverse comparison predicate for the specified
/// minimum/maximum flavor.
CmpInst::Predicate getInverseMinMaxPred(SelectPatternFlavor SPF);

/// Return true if RHS is known to be implied true by LHS.  Return false if
/// RHS is known to be implied false by LHS.  Otherwise, return None if no
/// implication can be made.
/// A & B must be i1 (boolean) values or a vector of such values. Note that
/// the truth table for implication is the same as <=u on i1 values (but not
/// <=s!).  The truth table for both is:
///    | T | F (B)
///  T | T | F
///  F | T | T
/// (A)
Optional<bool> isImpliedCondition(const Value *LHS, const Value *RHS,
                                  const DataLayout &DL, bool LHSIsTrue = true,
                                  unsigned Depth = 0);

/// Return the boolean condition value in the context of the given instruction
/// if it is known based on dominating conditions.
Optional<bool> isImpliedByDomCondition(const Value *Cond,
                                       const Instruction *ContextI,
                                       const DataLayout &DL);

/// If Ptr1 is provably equal to Ptr2 plus a constant offset, return that
/// offset. For example, Ptr1 might be &A[42], and Ptr2 might be &A[40]. In
/// this case offset would be -8.
Optional<int64_t> isPointerOffset(const Value *Ptr1, const Value *Ptr2,
                                  const DataLayout &DL);
678} // end namespace llvm

680#endif // LLVM_ANALYSIS_VALUETRACKING_H