/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/llvm/lib/Analysis/ValueTracking.cpp

Bug Summary

File:	build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/llvm/lib/Analysis/ValueTracking.cpp
Warning:	line 211, column 31 Called C++ object pointer is null
Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -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 -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm -resource-dir /usr/lib/llvm-15/lib/clang/15.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I lib/Analysis -I /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/llvm/lib/Analysis -I include -I /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/llvm/include -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-15/lib/clang/15.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm=build-llvm -fmacro-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/= -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm=build-llvm -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/= -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm -fdebug-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm=build-llvm -fdebug-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2022-04-20-140412-16051-1 -x c++ /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/llvm/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/AssumeBundleQueries.h"
28#include "llvm/Analysis/AssumptionCache.h"
29#include "llvm/Analysis/EHPersonalities.h"
30#include "llvm/Analysis/GuardUtils.h"
31#include "llvm/Analysis/InstructionSimplify.h"
32#include "llvm/Analysis/Loads.h"
33#include "llvm/Analysis/LoopInfo.h"
34#include "llvm/Analysis/OptimizationRemarkEmitter.h"
35#include "llvm/Analysis/TargetLibraryInfo.h"
36#include "llvm/IR/Argument.h"
37#include "llvm/IR/Attributes.h"
38#include "llvm/IR/BasicBlock.h"
39#include "llvm/IR/Constant.h"
40#include "llvm/IR/ConstantRange.h"
41#include "llvm/IR/Constants.h"
42#include "llvm/IR/DerivedTypes.h"
43#include "llvm/IR/DiagnosticInfo.h"
44#include "llvm/IR/Dominators.h"
45#include "llvm/IR/Function.h"
46#include "llvm/IR/GetElementPtrTypeIterator.h"
47#include "llvm/IR/GlobalAlias.h"
48#include "llvm/IR/GlobalValue.h"
49#include "llvm/IR/GlobalVariable.h"
50#include "llvm/IR/InstrTypes.h"
51#include "llvm/IR/Instruction.h"
52#include "llvm/IR/Instructions.h"
53#include "llvm/IR/IntrinsicInst.h"
54#include "llvm/IR/Intrinsics.h"
55#include "llvm/IR/IntrinsicsAArch64.h"
56#include "llvm/IR/IntrinsicsRISCV.h"
57#include "llvm/IR/IntrinsicsX86.h"
58#include "llvm/IR/LLVMContext.h"
59#include "llvm/IR/Metadata.h"
60#include "llvm/IR/Module.h"
61#include "llvm/IR/Operator.h"
62#include "llvm/IR/PatternMatch.h"
63#include "llvm/IR/Type.h"
64#include "llvm/IR/User.h"
65#include "llvm/IR/Value.h"
66#include "llvm/Support/Casting.h"
67#include "llvm/Support/CommandLine.h"
68#include "llvm/Support/Compiler.h"
69#include "llvm/Support/ErrorHandling.h"
70#include "llvm/Support/KnownBits.h"
71#include "llvm/Support/MathExtras.h"
72#include <algorithm>
73#include <cassert>
74#include <cstdint>
75#include <utility>

77using namespace llvm;
78using namespace llvm::PatternMatch;

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// According to the LangRef, branching on a poison condition is absolutely
86// immediate full UB.  However, historically we haven't implemented that
87// consistently as we have an important transformation (non-trivial unswitch)
88// which introduces instances of branch on poison/undef to otherwise well
89// defined programs.  This flag exists to let us test optimization benefit
90// of exploiting the specified behavior (in combination with enabling the
91// unswitch fix.)
92static cl::opt<bool> BranchOnPoisonAsUB("branch-on-poison-as-ub",
                                      cl::Hidden, cl::init(false));


96/// Returns the bitwidth of the given scalar or pointer type. For vector types,
97/// returns the element type's bitwidth.
98static unsigned getBitWidth(Type *Ty, const DataLayout &DL) {
if (unsigned BitWidth = Ty->getScalarSizeInBits())
  return BitWidth;

return DL.getPointerTypeSizeInBits(Ty);
103}

105namespace {

107// Simplifying using an assume can only be done in a particular control-flow
108// context (the context instruction provides that context). If an assume and
109// the context instruction are not in the same block then the DT helps in
110// figuring out if we can use it.
111struct 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;

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

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) {}
128};

130} // end anonymous namespace

132// Given the provided Value and, potentially, a context instruction, return
133// the preferred context instruction (if any).
134static 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;
146}

148static const Instruction *safeCxtI(const Value *V1, const Value *V2, 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>(V1);
if (CxtI && CxtI->getParent())
  return CxtI;

CxtI = dyn_cast<Instruction>(V2);
if (CxtI && CxtI->getParent())
  return CxtI;

return nullptr;
164}

166static bool getShuffleDemandedElts(const ShuffleVectorInst *Shuf,
                                 const APInt &DemandedElts,
                                 APInt &DemandedLHS, APInt &DemandedRHS) {
// The length of scalable vectors is unknown at compile time, thus we
// cannot check their values
if (isa<ScalableVectorType>(Shuf->getType()))
  return false;

int NumElts =
    cast<FixedVectorType>(Shuf->getOperand(0)->getType())->getNumElements();
int NumMaskElts = cast<FixedVectorType>(Shuf->getType())->getNumElements();
DemandedLHS = DemandedRHS = APInt::getZero(NumElts);
if (DemandedElts.isZero())
  return true;
// Simple case of a shuffle with zeroinitializer.
if (all_of(Shuf->getShuffleMask(), [](int Elt) { return Elt == 0; })) {
  DemandedLHS.setBit(0);
  return true;
}
for (int i = 0; i != NumMaskElts; ++i) {
  if (!DemandedElts[i])
    continue;
  int M = Shuf->getMaskValue(i);
  assert(M < (NumElts * 2) && "Invalid shuffle mask constant")(static_cast <bool> (M < (NumElts * 2) && "Invalid shuffle mask constant"
) ? void (0) : __assert_fail ("M < (NumElts * 2) && \"Invalid shuffle mask constant\""
, "llvm/lib/Analysis/ValueTracking.cpp", 189, __extension__ __PRETTY_FUNCTION__
));

  // For undef elements, we don't know anything about the common state of
  // the shuffle result.
  if (M == -1)
    return false;
  if (M < NumElts)
    DemandedLHS.setBit(M % NumElts);
  else
    DemandedRHS.setBit(M % NumElts);
}

return true;
202}

204static void computeKnownBits(const Value *V, const APInt &DemandedElts,
                           KnownBits &Known, unsigned Depth, const Query &Q);

207static void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth,
                           const Query &Q) {
// FIXME: We currently have no way to represent the DemandedElts of a scalable
// vector
if (isa<ScalableVectorType>(V->getType())) {
19
←
Called C++ object pointer is null
  Known.resetAll();
  return;
}

auto *FVTy = dyn_cast<FixedVectorType>(V->getType());
APInt DemandedElts =
    FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1);
computeKnownBits(V, DemandedElts, Known, Depth, Q);
220}

222void 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));
229}

231void llvm::computeKnownBits(const Value *V, const APInt &DemandedElts,
                          KnownBits &Known, const DataLayout &DL,
                          unsigned Depth, AssumptionCache *AC,
                          const Instruction *CxtI, const DominatorTree *DT,
                          OptimizationRemarkEmitter *ORE, bool UseInstrInfo) {
::computeKnownBits(V, DemandedElts, Known, Depth,
                   Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE));
238}

240static KnownBits computeKnownBits(const Value *V, const APInt &DemandedElts,
                                unsigned Depth, const Query &Q);

243static KnownBits computeKnownBits(const Value *V, unsigned Depth,
                                const Query &Q);

246KnownBits 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));
254}

256KnownBits llvm::computeKnownBits(const Value *V, const APInt &DemandedElts,
                               const DataLayout &DL, unsigned Depth,
                               AssumptionCache *AC, const Instruction *CxtI,
                               const DominatorTree *DT,
                               OptimizationRemarkEmitter *ORE,
                               bool UseInstrInfo) {
return ::computeKnownBits(
    V, DemandedElts, Depth,
    Query(DL, AC, safeCxtI(V, CxtI), DT, UseInstrInfo, ORE));
265}

267bool 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() &&(static_cast <bool> (LHS->getType() == RHS->getType
() && "LHS and RHS should have the same type") ? void
 (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"LHS and RHS should have the same type\""
, "llvm/lib/Analysis/ValueTracking.cpp", 272, __extension__ __PRETTY_FUNCTION__
))
       "LHS and RHS should have the same type")(static_cast <bool> (LHS->getType() == RHS->getType
() && "LHS and RHS should have the same type") ? void
 (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"LHS and RHS should have the same type\""
, "llvm/lib/Analysis/ValueTracking.cpp", 272, __extension__ __PRETTY_FUNCTION__
));
assert(LHS->getType()->isIntOrIntVectorTy() &&(static_cast <bool> (LHS->getType()->isIntOrIntVectorTy
() && "LHS and RHS should be integers") ? void (0) : __assert_fail
 ("LHS->getType()->isIntOrIntVectorTy() && \"LHS and RHS should be integers\""
, "llvm/lib/Analysis/ValueTracking.cpp", 274, __extension__ __PRETTY_FUNCTION__
))
       "LHS and RHS should be integers")(static_cast <bool> (LHS->getType()->isIntOrIntVectorTy
() && "LHS and RHS should be integers") ? void (0) : __assert_fail
 ("LHS->getType()->isIntOrIntVectorTy() && \"LHS and RHS should be integers\""
, "llvm/lib/Analysis/ValueTracking.cpp", 274, __extension__ __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;
}
// Look for: (A & B) op ~(A | B)
{
  Value *A, *B;
  if (match(LHS, m_And(m_Value(A), m_Value(B))) &&
      match(RHS, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
    return true;
  if (match(RHS, m_And(m_Value(A), m_Value(B))) &&
      match(LHS, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
    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 KnownBits::haveNoCommonBitsSet(LHSKnown, RHSKnown);
301}

303bool llvm::isOnlyUsedInZeroEqualityComparison(const Instruction *I) {
return !I->user_empty() && all_of(I->users(), [](const User *U) {
  ICmpInst::Predicate P;
  return match(U, m_ICmp(P, m_Value(), m_Zero())) && ICmpInst::isEquality(P);
});
308}

310static bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth,
                                 const Query &Q);

313bool 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));
319}

321static bool isKnownNonZero(const Value *V, const APInt &DemandedElts,
                         unsigned Depth, const Query &Q);

324static bool isKnownNonZero(const Value *V, unsigned Depth, const Query &Q);

326bool 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));
331}

333bool 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();
340}

342bool 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);
352}

354bool 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();
360}

362static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth,
                          const Query &Q);

365bool 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, 0,
                         Query(DL, AC, safeCxtI(V2, V1, CxtI), DT,
                               UseInstrInfo, /*ORE=*/nullptr));
372}

374static bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth,
                            const Query &Q);

377bool 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));
383}

385static unsigned ComputeNumSignBits(const Value *V, const APInt &DemandedElts,
                                 unsigned Depth, const Query &Q);

388static unsigned ComputeNumSignBits(const Value *V, unsigned Depth,
                                 const Query &Q) {
// FIXME: We currently have no way to represent the DemandedElts of a scalable
// vector
if (isa<ScalableVectorType>(V->getType()))
  return 1;

auto *FVTy = dyn_cast<FixedVectorType>(V->getType());
APInt DemandedElts =
    FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1);
return ComputeNumSignBits(V, DemandedElts, Depth, Q);
399}

401unsigned 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));
407}

409unsigned llvm::ComputeMaxSignificantBits(const Value *V, const DataLayout &DL,
                                       unsigned Depth, AssumptionCache *AC,
                                       const Instruction *CxtI,
                                       const DominatorTree *DT) {
unsigned SignBits = ComputeNumSignBits(V, DL, Depth, AC, CxtI, DT);
return V->getType()->getScalarSizeInBits() - SignBits + 1;
415}

417static void computeKnownBitsAddSub(bool Add, const Value *Op0, const Value *Op1,
                                 bool NSW, const APInt &DemandedElts,
                                 KnownBits &KnownOut, KnownBits &Known2,
                                 unsigned Depth, const Query &Q) {
computeKnownBits(Op1, DemandedElts, KnownOut, Depth + 1, Q);

// If one operand is unknown and we have no nowrap information,
// the result will be unknown independently of the second operand.
if (KnownOut.isUnknown() && !NSW)
  return;

computeKnownBits(Op0, DemandedElts, Known2, Depth + 1, Q);
KnownOut = KnownBits::computeForAddSub(Add, NSW, Known2, KnownOut);
430}

432static void computeKnownBitsMul(const Value *Op0, const Value *Op1, bool NSW,
                              const APInt &DemandedElts, KnownBits &Known,
                              KnownBits &Known2, unsigned Depth,
                              const Query &Q) {
computeKnownBits(Op1, DemandedElts, Known, Depth + 1, Q);
computeKnownBits(Op0, DemandedElts, 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 &&
           Known2.isNonZero()) ||
          (isKnownNegativeOp0 && isKnownNonNegativeOp1 && Known.isNonZero());
  }
}

bool SelfMultiply = Op0 == Op1;
// TODO: SelfMultiply can be poison, but not undef.
if (SelfMultiply)
  SelfMultiply &=
      isGuaranteedNotToBeUndefOrPoison(Op0, Q.AC, Q.CxtI, Q.DT, Depth + 1);
Known = KnownBits::mul(Known, Known2, SelfMultiply);

// 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();
480}

482void llvm::computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
                                           KnownBits &Known) {
unsigned BitWidth = Known.getBitWidth();
unsigned NumRanges = Ranges.getNumOperands() / 2;
assert(NumRanges >= 1)(static_cast <bool> (NumRanges >= 1) ? void (0) : __assert_fail
 ("NumRanges >= 1", "llvm/lib/Analysis/ValueTracking.cpp",
 486, __extension__ __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);
  APInt UnsignedMax = Range.getUnsignedMax().zextOrTrunc(BitWidth);
  Known.One &= UnsignedMax & Mask;
  Known.Zero &= ~UnsignedMax & Mask;
}
506}

508static 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 || (isa<Instruction>(V) &&
                   !cast<Instruction>(V)->mayHaveSideEffects() &&
                   !cast<Instruction>(V)->isTerminator())) {
     EphValues.insert(V);
     if (const User *U = dyn_cast<User>(V))
       append_range(WorkSet, U->operands());
    }
  }
}

return false;
542}

544// Is this an intrinsic that cannot be speculated but also cannot trap?
545bool llvm::isAssumeLikeIntrinsic(const Instruction *I) {
if (const IntrinsicInst *CI = dyn_cast<IntrinsicInst>(I))
  return CI->isAssumeLikeIntrinsic();

return false;
550}

552bool 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 (Inv->getParent() == CxtI->getParent()) {
  // If Inv and CtxI are in the same block, check if the assume (Inv) is first
  // in the BB.
  if (Inv->comesBefore(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, not even CxtI itself.
  // We limit the scan distance between the assume and its context instruction
  // to avoid a compile-time explosion. This limit is chosen arbitrarily, so
  // it can be adjusted if needed (could be turned into a cl::opt).
  auto Range = make_range(CxtI->getIterator(), Inv->getIterator());
  if (!isGuaranteedToTransferExecutionToSuccessor(Range, 15))
    return false;

  return !isEphemeralValueOf(Inv, CxtI);
}

// Inv and CxtI are in different blocks.
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;
}

return false;
598}

600static bool cmpExcludesZero(CmpInst::Predicate Pred, const Value *RHS) {
// v u> y implies v != 0.
if (Pred == ICmpInst::ICMP_UGT)
  return true;

// Special-case v != 0 to also handle v != null.
if (Pred == ICmpInst::ICMP_NE)
  return match(RHS, m_Zero());

// All other predicates - rely on generic ConstantRange handling.
const APInt *C;
if (!match(RHS, m_APInt(C)))
  return false;

ConstantRange TrueValues = ConstantRange::makeExactICmpRegion(Pred, *C);
return !TrueValues.contains(APInt::getZero(C->getBitWidth()));
616}

618static bool isKnownNonZeroFromAssume(const Value *V, 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 false;

if (Q.CxtI && V->getType()->isPointerTy()) {
  SmallVector<Attribute::AttrKind, 2> AttrKinds{Attribute::NonNull};
  if (!NullPointerIsDefined(Q.CxtI->getFunction(),
                            V->getType()->getPointerAddressSpace()))
    AttrKinds.push_back(Attribute::Dereferenceable);

  if (getKnowledgeValidInContext(V, AttrKinds, Q.CxtI, Q.DT, Q.AC))
    return true;
}

for (auto &AssumeVH : Q.AC->assumptionsFor(V)) {
  if (!AssumeVH)
    continue;
  CallInst *I = cast<CallInst>(AssumeVH);
  assert(I->getFunction() == Q.CxtI->getFunction() &&(static_cast <bool> (I->getFunction() == Q.CxtI->
getFunction() && "Got assumption for the wrong function!"
) ? void (0) : __assert_fail ("I->getFunction() == Q.CxtI->getFunction() && \"Got assumption for the wrong function!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 639, __extension__ __PRETTY_FUNCTION__
))
         "Got assumption for the wrong function!")(static_cast <bool> (I->getFunction() == Q.CxtI->
getFunction() && "Got assumption for the wrong function!"
) ? void (0) : __assert_fail ("I->getFunction() == Q.CxtI->getFunction() && \"Got assumption for the wrong function!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 639, __extension__ __PRETTY_FUNCTION__
));

  // 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 &&(static_cast <bool> (I->getCalledFunction()->getIntrinsicID
() == Intrinsic::assume && "must be an assume intrinsic"
) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\""
, "llvm/lib/Analysis/ValueTracking.cpp", 646, __extension__ __PRETTY_FUNCTION__
))
         "must be an assume intrinsic")(static_cast <bool> (I->getCalledFunction()->getIntrinsicID
() == Intrinsic::assume && "must be an assume intrinsic"
) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\""
, "llvm/lib/Analysis/ValueTracking.cpp", 646, __extension__ __PRETTY_FUNCTION__
));

  Value *RHS;
  CmpInst::Predicate Pred;
  auto m_V = m_CombineOr(m_Specific(V), m_PtrToInt(m_Specific(V)));
  if (!match(I->getArgOperand(0), m_c_ICmp(Pred, m_V, m_Value(RHS))))
    return false;

  if (cmpExcludesZero(Pred, RHS) && isValidAssumeForContext(I, Q.CxtI, Q.DT))
    return true;
}

return false;
659}

661static 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();

// Refine Known set if the pointer alignment is set by assume bundles.
if (V->getType()->isPointerTy()) {
  if (RetainedKnowledge RK = getKnowledgeValidInContext(
          V, {Attribute::Alignment}, Q.CxtI, Q.DT, Q.AC)) {
    if (isPowerOf2_64(RK.ArgValue))
      Known.Zero.setLowBits(Log2_64(RK.ArgValue));
  }
}

// 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() &&(static_cast <bool> (I->getParent()->getParent() ==
 Q.CxtI->getParent()->getParent() && "Got assumption for the wrong function!"
) ? void (0) : __assert_fail ("I->getParent()->getParent() == Q.CxtI->getParent()->getParent() && \"Got assumption for the wrong function!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 687, __extension__ __PRETTY_FUNCTION__
))
         "Got assumption for the wrong function!")(static_cast <bool> (I->getParent()->getParent() ==
 Q.CxtI->getParent()->getParent() && "Got assumption for the wrong function!"
) ? void (0) : __assert_fail ("I->getParent()->getParent() == Q.CxtI->getParent()->getParent() && \"Got assumption for the wrong function!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 687, __extension__ __PRETTY_FUNCTION__
));

  // 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 &&(static_cast <bool> (I->getCalledFunction()->getIntrinsicID
() == Intrinsic::assume && "must be an assume intrinsic"
) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\""
, "llvm/lib/Analysis/ValueTracking.cpp", 694, __extension__ __PRETTY_FUNCTION__
))
         "must be an assume intrinsic")(static_cast <bool> (I->getCalledFunction()->getIntrinsicID
() == Intrinsic::assume && "must be an assume intrinsic"
) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\""
, "llvm/lib/Analysis/ValueTracking.cpp", 694, __extension__ __PRETTY_FUNCTION__
));

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

  if (Arg == V && isValidAssumeForContext(I, Q.CxtI, Q.DT)) {
    assert(BitWidth == 1 && "assume operand is not i1?")(static_cast <bool> (BitWidth == 1 && "assume operand is not i1?"
) ? void (0) : __assert_fail ("BitWidth == 1 && \"assume operand is not i1?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 699, __extension__ __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?")(static_cast <bool> (BitWidth == 1 && "assume operand is not i1?"
) ? void (0) : __assert_fail ("BitWidth == 1 && \"assume operand is not i1?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 705, __extension__ __PRETTY_FUNCTION__
));
    Known.setAllZero();
    return;
  }

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

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

  // We are attempting to compute known bits for the operands of an assume.
  // Do not try to use other assumptions for those recursive calls because
  // that can lead to mutual recursion and a compile-time explosion.
  // An example of the mutual recursion: computeKnownBits can call
  // isKnownNonZero which calls computeKnownBitsFromAssume (this function)
  // and so on.
  Query QueryNoAC = Q;
  QueryNoAC.AC = nullptr;

  // Note that ptrtoint may change the bitwidth.
  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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);
      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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);
      KnownBits MaskKnown =
          computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);

      // 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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);
      KnownBits MaskKnown =
          computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);

      // 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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);
      KnownBits BKnown =
          computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);

      // 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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);
      KnownBits BKnown =
          computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);

      // 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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);
      KnownBits BKnown =
          computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);

      // 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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);
      KnownBits BKnown =
          computeKnownBits(B, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);

      // 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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);

      // 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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);
      // 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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);
      // 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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);
      // 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 =
          computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth);

      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 =
          computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth);

      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 =
          computeKnownBits(A, Depth + 1, QueryNoAC).anyextOrTrunc(BitWidth);

      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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);

      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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);

      // 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 =
          computeKnownBits(A, Depth+1, QueryNoAC).anyextOrTrunc(BitWidth);

      // 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, QueryNoAC))
        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.";
    });
}
982}

984/// Compute known bits from a shift operator, including those with a
985/// non-constant shift amount. Known is the output of this function. Known2 is a
986/// pre-allocated temporary with the same bit width as Known and on return
987/// contains the known bit of the shift value source. KF is an
988/// operator-specific function that, given the known-bits and a shift amount,
989/// compute the implied known-bits of the shift operator's result respectively
990/// for that shift amount. The results from calling KF are conservatively
991/// combined for all permitted shift amounts.
992static void computeKnownBitsFromShiftOperator(
  const Operator *I, const APInt &DemandedElts, KnownBits &Known,
  KnownBits &Known2, unsigned Depth, const Query &Q,
  function_ref<KnownBits(const KnownBits &, const KnownBits &)> KF) {
unsigned BitWidth = Known.getBitWidth();
computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q);
computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q);

// 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();
bool ShiftAmtIsConstant = Known.isConstant();
bool MaxShiftAmtIsOutOfRange = Known.getMaxValue().uge(BitWidth);

if (ShiftAmtIsConstant) {
  Known = KF(Known2, Known);

  // 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;
}

// 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 (MaxShiftAmtIsOutOfRange) {
  Known.resetAll();
  return;
}

// 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), DemandedElts, Depth + 1, Q);
  if (!*ShifterOperandIsNonZero)
    return;
}

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), DemandedElts, Depth + 1, Q);
    if (*ShifterOperandIsNonZero)
      continue;
  }

  Known = KnownBits::commonBits(
      Known, KF(Known2, KnownBits::makeConstant(APInt(32, 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();
1075}

1077static void computeKnownBitsFromOperator(const Operator *I,
                                       const APInt &DemandedElts,
                                       KnownBits &Known, unsigned Depth,
                                       const Query &Q) {
unsigned BitWidth = Known.getBitWidth();

KnownBits Known2(BitWidth);
switch (I->getOpcode()) {
1
Control jumps to 'case PHI:'  at line 1424→
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), DemandedElts, Known, Depth + 1, Q);
  computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q);

  Known &= Known2;

  // 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, DemandedElts, Known2, Depth + 1, Q);
    if (Known2.countMinTrailingOnes() > 0)
      Known.Zero.setBit(0);
  }
  break;
}
case Instruction::Or:
  computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q);
  computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q);

  Known |= Known2;
  break;
case Instruction::Xor:
  computeKnownBits(I->getOperand(1), DemandedElts, Known, Depth + 1, Q);
  computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q);

  Known ^= Known2;
  break;
case Instruction::Mul: {
  bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I));
  computeKnownBitsMul(I->getOperand(0), I->getOperand(1), NSW, DemandedElts,
                      Known, Known2, Depth, Q);
  break;
}
case Instruction::UDiv: {
  computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
  computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
  Known = KnownBits::udiv(Known, Known2);
  break;
}
case Instruction::Select: {
  const Value *LHS = nullptr, *RHS = nullptr;
  SelectPatternFlavor SPF = matchSelectPattern(I, LHS, RHS).Flavor;
  if (SelectPatternResult::isMinOrMax(SPF)) {
    computeKnownBits(RHS, Known, Depth + 1, Q);
    computeKnownBits(LHS, Known2, Depth + 1, Q);
    switch (SPF) {
    default:
      llvm_unreachable("Unhandled select pattern flavor!")::llvm::llvm_unreachable_internal("Unhandled select pattern flavor!"
, "llvm/lib/Analysis/ValueTracking.cpp", 1145);
    case SPF_SMAX:
      Known = KnownBits::smax(Known, Known2);
      break;
    case SPF_SMIN:
      Known = KnownBits::smin(Known, Known2);
      break;
    case SPF_UMAX:
      Known = KnownBits::umax(Known, Known2);
      break;
    case SPF_UMIN:
      Known = KnownBits::umin(Known, Known2);
      break;
    }
    break;
  }

  computeKnownBits(I->getOperand(2), Known, Depth + 1, Q);
  computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);

  // Only known if known in both the LHS and RHS.
  Known = KnownBits::commonBits(Known, Known2);

  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<OverflowingBinaryOperator>(RHS)))
      Known.Zero.setSignBit();
  }

  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.getPointerTypeSizeInBits(ScalarTy) :
    Q.DL.getTypeSizeInBits(ScalarTy);

  assert(SrcBitWidth && "SrcBitWidth can't be zero")(static_cast <bool> (SrcBitWidth && "SrcBitWidth can't be zero"
) ? void (0) : __assert_fail ("SrcBitWidth && \"SrcBitWidth can't be zero\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1202, __extension__ __PRETTY_FUNCTION__
));
  Known = Known.anyextOrTrunc(SrcBitWidth);
  computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
  Known = Known.zextOrTrunc(BitWidth);
  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;
  }

  // Handle cast from vector integer type to scalar or vector integer.
  auto *SrcVecTy = dyn_cast<FixedVectorType>(SrcTy);
  if (!SrcVecTy || !SrcVecTy->getElementType()->isIntegerTy() ||
      !I->getType()->isIntOrIntVectorTy())
    break;

  // Look through a cast from narrow vector elements to wider type.
  // Examples: v4i32 -> v2i64, v3i8 -> v24
  unsigned SubBitWidth = SrcVecTy->getScalarSizeInBits();
  if (BitWidth % SubBitWidth == 0) {
    // Known bits are automatically intersected across demanded elements of a
    // vector. So for example, if a bit is computed as known zero, it must be
    // zero across all demanded elements of the vector.
    //
    // For this bitcast, each demanded element of the output is sub-divided
    // across a set of smaller vector elements in the source vector. To get
    // the known bits for an entire element of the output, compute the known
    // bits for each sub-element sequentially. This is done by shifting the
    // one-set-bit demanded elements parameter across the sub-elements for
    // consecutive calls to computeKnownBits. We are using the demanded
    // elements parameter as a mask operator.
    //
    // The known bits of each sub-element are then inserted into place
    // (dependent on endian) to form the full result of known bits.
    unsigned NumElts = DemandedElts.getBitWidth();
    unsigned SubScale = BitWidth / SubBitWidth;
    APInt SubDemandedElts = APInt::getZero(NumElts * SubScale);
    for (unsigned i = 0; i != NumElts; ++i) {
      if (DemandedElts[i])
        SubDemandedElts.setBit(i * SubScale);
    }

    KnownBits KnownSrc(SubBitWidth);
    for (unsigned i = 0; i != SubScale; ++i) {
      computeKnownBits(I->getOperand(0), SubDemandedElts.shl(i), KnownSrc,
                       Depth + 1, Q);
      unsigned ShiftElt = Q.DL.isLittleEndian() ? i : SubScale - 1 - i;
      Known.insertBits(KnownSrc, ShiftElt * SubBitWidth);
    }
  }
  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: {
  bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I));
  auto KF = [NSW](const KnownBits &KnownVal, const KnownBits &KnownAmt) {
    KnownBits Result = KnownBits::shl(KnownVal, KnownAmt);
    // 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) {
      if (KnownVal.Zero.isSignBitSet())
        Result.Zero.setSignBit();
      if (KnownVal.One.isSignBitSet())
        Result.One.setSignBit();
    }
    return Result;
  };
  computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q,
                                    KF);
  // Trailing zeros of a right-shifted constant never decrease.
  const APInt *C;
  if (match(I->getOperand(0), m_APInt(C)))
    Known.Zero.setLowBits(C->countTrailingZeros());
  break;
}
case Instruction::LShr: {
  auto KF = [](const KnownBits &KnownVal, const KnownBits &KnownAmt) {
    return KnownBits::lshr(KnownVal, KnownAmt);
  };
  computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q,
                                    KF);
  // Leading zeros of a left-shifted constant never decrease.
  const APInt *C;
  if (match(I->getOperand(0), m_APInt(C)))
    Known.Zero.setHighBits(C->countLeadingZeros());
  break;
}
case Instruction::AShr: {
  auto KF = [](const KnownBits &KnownVal, const KnownBits &KnownAmt) {
    return KnownBits::ashr(KnownVal, KnownAmt);
  };
  computeKnownBitsFromShiftOperator(I, DemandedElts, Known, Known2, Depth, Q,
                                    KF);
  break;
}
case Instruction::Sub: {
  bool NSW = Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(I));
  computeKnownBitsAddSub(false, I->getOperand(0), I->getOperand(1), NSW,
                         DemandedElts, 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,
                         DemandedElts, Known, Known2, Depth, Q);
  break;
}
case Instruction::SRem:
  computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
  computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
  Known = KnownBits::srem(Known, Known2);
  break;

case Instruction::URem:
  computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
  computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
  Known = KnownBits::urem(Known, Known2);
  break;
case Instruction::Alloca:
  Known.Zero.setLowBits(Log2(cast<AllocaInst>(I)->getAlign()));
  break;
case Instruction::GetElementPtr: {
  // Analyze all of the subscripts of this getelementptr instruction
  // to determine if we can prove known low zero bits.
  computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
  // Accumulate the constant indices in a separate variable
  // to minimize the number of calls to computeForAddSub.
  APInt AccConstIndices(BitWidth, 0, /*IsSigned*/ true);

  gep_type_iterator GTI = gep_type_begin(I);
  for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i, ++GTI) {
    // TrailZ can only become smaller, short-circuit if we hit zero.
    if (Known.isUnknown())
      break;

    Value *Index = I->getOperand(i);

    // Handle case when index is zero.
    Constant *CIndex = dyn_cast<Constant>(Index);
    if (CIndex && CIndex->isZeroValue())
      continue;

    if (StructType *STy = GTI.getStructTypeOrNull()) {
      // Handle struct member offset arithmetic.

      assert(CIndex &&(static_cast <bool> (CIndex && "Access to structure field must be known at compile time"
) ? void (0) : __assert_fail ("CIndex && \"Access to structure field must be known at compile time\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1364, __extension__ __PRETTY_FUNCTION__
))
             "Access to structure field must be known at compile time")(static_cast <bool> (CIndex && "Access to structure field must be known at compile time"
) ? void (0) : __assert_fail ("CIndex && \"Access to structure field must be known at compile time\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1364, __extension__ __PRETTY_FUNCTION__
));

      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);
      AccConstIndices += Offset;
      continue;
    }

    // Handle array index arithmetic.
    Type *IndexedTy = GTI.getIndexedType();
    if (!IndexedTy->isSized()) {
      Known.resetAll();
      break;
    }

    unsigned IndexBitWidth = Index->getType()->getScalarSizeInBits();
    KnownBits IndexBits(IndexBitWidth);
    computeKnownBits(Index, IndexBits, Depth + 1, Q);
    TypeSize IndexTypeSize = Q.DL.getTypeAllocSize(IndexedTy);
    uint64_t TypeSizeInBytes = IndexTypeSize.getKnownMinSize();
    KnownBits ScalingFactor(IndexBitWidth);
    // Multiply by current sizeof type.
    // &A[i] == A + i * sizeof(*A[i]).
    if (IndexTypeSize.isScalable()) {
      // For scalable types the only thing we know about sizeof is
      // that this is a multiple of the minimum size.
      ScalingFactor.Zero.setLowBits(countTrailingZeros(TypeSizeInBytes));
    } else if (IndexBits.isConstant()) {
      APInt IndexConst = IndexBits.getConstant();
      APInt ScalingFactor(IndexBitWidth, TypeSizeInBytes);
      IndexConst *= ScalingFactor;
      AccConstIndices += IndexConst.sextOrTrunc(BitWidth);
      continue;
    } else {
      ScalingFactor =
          KnownBits::makeConstant(APInt(IndexBitWidth, TypeSizeInBytes));
    }
    IndexBits = KnownBits::mul(IndexBits, ScalingFactor);

    // If the offsets have a different width from the pointer, according
    // to the language reference we need to sign-extend or truncate them
    // to the width of the pointer.
    IndexBits = IndexBits.sextOrTrunc(BitWidth);

    // Note that inbounds does *not* guarantee nsw for the addition, as only
    // the offset is signed, while the base address is unsigned.
    Known = KnownBits::computeForAddSub(
        /*Add=*/true, /*NSW=*/false, Known, IndexBits);
  }
  if (!Known.isUnknown() && !AccConstIndices.isZero()) {
    KnownBits Index = KnownBits::makeConstant(AccConstIndices);
    Known = KnownBits::computeForAddSub(
        /*Add=*/true, /*NSW=*/false, Known, Index);
  }
  break;
}
case Instruction::PHI: {
  const PHINode *P = cast<PHINode>(I);
2
←
'I' is a 'PHINode'→
  BinaryOperator *BO = nullptr;
  Value *R = nullptr, *L = nullptr;
  if (matchSimpleRecurrence(P, BO, R, L)) {
3
←
Value assigned to 'R'→
4
←
Assuming the condition is true→
5
←
Taking true branch→
    // 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.
    unsigned Opcode = BO->getOpcode();

    // If this is a shift recurrence, we know the bits being shifted in.
    // We can combine that with information about the start value of the
    // recurrence to conclude facts about the result.
    if ((Opcode == Instruction::LShr || Opcode == Instruction::AShr ||
6
←
Assuming 'Opcode' is not equal to LShr→
7
←
Assuming 'Opcode' is not equal to AShr→
         Opcode == Instruction::Shl) &&
8
←
Assuming 'Opcode' is not equal to Shl→
        BO->getOperand(0) == I) {

      // We have matched a recurrence of the form:
      // %iv = [R, %entry], [%iv.next, %backedge]
      // %iv.next = shift_op %iv, L

      // Recurse with the phi context to avoid concern about whether facts
      // inferred hold at original context instruction.  TODO: It may be
      // correct to use the original context.  IF warranted, explore and
      // add sufficient tests to cover.
      Query RecQ = Q;
      RecQ.CxtI = P;
      computeKnownBits(R, DemandedElts, Known2, Depth + 1, RecQ);
      switch (Opcode) {
      case Instruction::Shl:
        // A shl recurrence will only increase the tailing zeros
        Known.Zero.setLowBits(Known2.countMinTrailingZeros());
        break;
      case Instruction::LShr:
        // A lshr recurrence will preserve the leading zeros of the
        // start value
        Known.Zero.setHighBits(Known2.countMinLeadingZeros());
        break;
      case Instruction::AShr:
        // An ashr recurrence will extend the initial sign bit
        Known.Zero.setHighBits(Known2.countMinLeadingZeros());
        Known.One.setHighBits(Known2.countMinLeadingOnes());
        break;
      };
    }

    // 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 ||
9
←
Assuming 'Opcode' is not equal to Add→
14
←
Taking true branch→
        Opcode == Instruction::Sub ||
10
←
Assuming 'Opcode' is not equal to Sub→
        Opcode == Instruction::And ||
11
←
Assuming 'Opcode' is not equal to And→
        Opcode == Instruction::Or ||
12
←
Assuming 'Opcode' is not equal to Or→
        Opcode == Instruction::Mul) {
13
←
Assuming 'Opcode' is equal to Mul→
      // Change the context instruction to the "edge" that flows into the
      // phi. This is important because that is where the value is actually
      // "evaluated" even though it is used later somewhere else. (see also
      // D69571).
      Query RecQ = Q;

      unsigned OpNum = P->getOperand(0) == R ? 0 : 1;
15
←
Assuming pointer value is null→
16
←
'?' condition is true→
      Instruction *RInst = P->getIncomingBlock(OpNum)->getTerminator();
      Instruction *LInst = P->getIncomingBlock(1-OpNum)->getTerminator();

      // Ok, we have a PHI of the form L op= R. Check for low
      // zero bits.
      RecQ.CxtI = RInst;
      computeKnownBits(R, Known2, Depth + 1, RecQ);
17
←
Passing null pointer value via 1st parameter 'V'→
18
←
Calling 'computeKnownBits'→

      // We need to take the minimum number of known bits
      KnownBits Known3(BitWidth);
      RecQ.CxtI = LInst;
      computeKnownBits(L, Known3, Depth + 1, RecQ);

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

      auto *OverflowOp = dyn_cast<OverflowingBinaryOperator>(BO);
      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 && BO->getOperand(0) == 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 < MaxAnalysisRecursionDepth - 1 && !Known.Zero && !Known.One) {
    // Skip if every incoming value references to ourself.
    if (isa_and_nonnull<UndefValue>(P->hasConstantValue()))
      break;

    Known.Zero.setAllBits();
    Known.One.setAllBits();
    for (unsigned u = 0, e = P->getNumIncomingValues(); u < e; ++u) {
      Value *IncValue = P->getIncomingValue(u);
      // Skip direct self references.
      if (IncValue == P) continue;

      // Change the context instruction to the "edge" that flows into the
      // phi. This is important because that is where the value is actually
      // "evaluated" even though it is used later somewhere else. (see also
      // D69571).
      Query RecQ = Q;
      RecQ.CxtI = P->getIncomingBlock(u)->getTerminator();

      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, MaxAnalysisRecursionDepth - 1, RecQ);
      Known = KnownBits::commonBits(Known, Known2);
      // If all bits have been ruled out, there's no need to check
      // more operands.
      if (Known.isUnknown())
        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 = cast<CallBase>(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::abs: {
      computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
      bool IntMinIsPoison = match(II->getArgOperand(1), m_One());
      Known = Known2.abs(IntMinIsPoison);
      break;
    }
    case Intrinsic::bitreverse:
      computeKnownBits(I->getOperand(0), DemandedElts, Known2, Depth + 1, Q);
      Known.Zero |= Known2.Zero.reverseBits();
      Known.One |= Known2.One.reverseBits();
      break;
    case Intrinsic::bswap:
      computeKnownBits(I->getOperand(0), DemandedElts, 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.countMaxLeadingZeros();
      // If this call is poison for 0 input, 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.countMaxTrailingZeros();
      // If this call is poison for 0 input, 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(BitWidth);
      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::umin:
      computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
      computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
      Known = KnownBits::umin(Known, Known2);
      break;
    case Intrinsic::umax:
      computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
      computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
      Known = KnownBits::umax(Known, Known2);
      break;
    case Intrinsic::smin:
      computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
      computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
      Known = KnownBits::smin(Known, Known2);
      break;
    case Intrinsic::smax:
      computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
      computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
      Known = KnownBits::smax(Known, Known2);
      break;
    case Intrinsic::x86_sse42_crc32_64_64:
      Known.Zero.setBitsFrom(32);
      break;
    case Intrinsic::riscv_vsetvli:
    case Intrinsic::riscv_vsetvlimax:
      // Assume that VL output is positive and would fit in an int32_t.
      // TODO: VLEN might be capped at 16 bits in a future V spec update.
      if (BitWidth >= 32)
        Known.Zero.setBitsFrom(31);
      break;
    case Intrinsic::vscale: {
      if (!II->getParent() || !II->getFunction() ||
          !II->getFunction()->hasFnAttribute(Attribute::VScaleRange))
        break;

      auto Attr = II->getFunction()->getFnAttribute(Attribute::VScaleRange);
      Optional<unsigned> VScaleMax = Attr.getVScaleRangeMax();

      if (!VScaleMax)
        break;

      unsigned VScaleMin = Attr.getVScaleRangeMin();

      // If vscale min = max then we know the exact value at compile time
      // and hence we know the exact bits.
      if (VScaleMin == VScaleMax) {
        Known.One = VScaleMin;
        Known.Zero = VScaleMin;
        Known.Zero.flipAllBits();
        break;
      }

      unsigned FirstZeroHighBit =
          32 - countLeadingZeros(VScaleMax.getValue());
      if (FirstZeroHighBit < BitWidth)
        Known.Zero.setBitsFrom(FirstZeroHighBit);

      break;
    }
    }
  }
  break;
case Instruction::ShuffleVector: {
  auto *Shuf = dyn_cast<ShuffleVectorInst>(I);
  // FIXME: Do we need to handle ConstantExpr involving shufflevectors?
  if (!Shuf) {
    Known.resetAll();
    return;
  }
  // For undef elements, we don't know anything about the common state of
  // the shuffle result.
  APInt DemandedLHS, DemandedRHS;
  if (!getShuffleDemandedElts(Shuf, DemandedElts, DemandedLHS, DemandedRHS)) {
    Known.resetAll();
    return;
  }
  Known.One.setAllBits();
  Known.Zero.setAllBits();
  if (!!DemandedLHS) {
    const Value *LHS = Shuf->getOperand(0);
    computeKnownBits(LHS, DemandedLHS, Known, Depth + 1, Q);
    // If we don't know any bits, early out.
    if (Known.isUnknown())
      break;
  }
  if (!!DemandedRHS) {
    const Value *RHS = Shuf->getOperand(1);
    computeKnownBits(RHS, DemandedRHS, Known2, Depth + 1, Q);
    Known = KnownBits::commonBits(Known, Known2);
  }
  break;
}
case Instruction::InsertElement: {
  const Value *Vec = I->getOperand(0);
  const Value *Elt = I->getOperand(1);
  auto *CIdx = dyn_cast<ConstantInt>(I->getOperand(2));
  // Early out if the index is non-constant or out-of-range.
  unsigned NumElts = DemandedElts.getBitWidth();
  if (!CIdx || CIdx->getValue().uge(NumElts)) {
    Known.resetAll();
    return;
  }
  Known.One.setAllBits();
  Known.Zero.setAllBits();
  unsigned EltIdx = CIdx->getZExtValue();
  // Do we demand the inserted element?
  if (DemandedElts[EltIdx]) {
    computeKnownBits(Elt, Known, Depth + 1, Q);
    // If we don't know any bits, early out.
    if (Known.isUnknown())
      break;
  }
  // We don't need the base vector element that has been inserted.
  APInt DemandedVecElts = DemandedElts;
  DemandedVecElts.clearBit(EltIdx);
  if (!!DemandedVecElts) {
    computeKnownBits(Vec, DemandedVecElts, Known2, Depth + 1, Q);
    Known = KnownBits::commonBits(Known, Known2);
  }
  break;
}
case Instruction::ExtractElement: {
  // Look through extract element. If the index is non-constant or
  // out-of-range demand all elements, otherwise just the extracted element.
  const Value *Vec = I->getOperand(0);
  const Value *Idx = I->getOperand(1);
  auto *CIdx = dyn_cast<ConstantInt>(Idx);
  if (isa<ScalableVectorType>(Vec->getType())) {
    // FIXME: there's probably *something* we can do with scalable vectors
    Known.resetAll();
    break;
  }
  unsigned NumElts = cast<FixedVectorType>(Vec->getType())->getNumElements();
  APInt DemandedVecElts = APInt::getAllOnes(NumElts);
  if (CIdx && CIdx->getValue().ult(NumElts))
    DemandedVecElts = APInt::getOneBitSet(NumElts, CIdx->getZExtValue());
  computeKnownBits(Vec, DemandedVecElts, 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, DemandedElts,
                               Known, Known2, Depth, Q);
        break;
      case Intrinsic::usub_with_overflow:
      case Intrinsic::ssub_with_overflow:
        computeKnownBitsAddSub(false, II->getArgOperand(0),
                               II->getArgOperand(1), false, DemandedElts,
                               Known, Known2, Depth, Q);
        break;
      case Intrinsic::umul_with_overflow:
      case Intrinsic::smul_with_overflow:
        computeKnownBitsMul(II->getArgOperand(0), II->getArgOperand(1), false,
                            DemandedElts, Known, Known2, Depth, Q);
        break;
      }
    }
  }
  break;
case Instruction::Freeze:
  if (isGuaranteedNotToBePoison(I->getOperand(0), Q.AC, Q.CxtI, Q.DT,
                                Depth + 1))
    computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
  break;
}
1866}

1868/// Determine which bits of V are known to be either zero or one and return
1869/// them.
1870KnownBits computeKnownBits(const Value *V, const APInt &DemandedElts,
                         unsigned Depth, const Query &Q) {
KnownBits Known(getBitWidth(V->getType(), Q.DL));
computeKnownBits(V, DemandedElts, Known, Depth, Q);
return Known;
1875}

1877/// Determine which bits of V are known to be either zero or one and return
1878/// them.
1879KnownBits computeKnownBits(const Value *V, unsigned Depth, const Query &Q) {
KnownBits Known(getBitWidth(V->getType(), Q.DL));
computeKnownBits(V, Known, Depth, Q);
return Known;
1883}

1885/// Determine which bits of V are known to be either zero or one and return
1886/// them in the Known bit set.
1887///
1888/// NOTE: we cannot consider 'undef' to be "IsZero" here.  The problem is that
1889/// we cannot optimize based on the assumption that it is zero without changing
1890/// it to be an explicit zero.  If we don't change it to zero, other code could
1891/// optimized based on the contradictory assumption that it is non-zero.
1892/// Because instcombine aggressively folds operations with undef args anyway,
1893/// this won't lose us code quality.
1894///
1895/// This function is defined on values with integer type, values with pointer
1896/// type, and vectors of integers.  In the case
1897/// where V is a vector, known zero, and known one values are the
1898/// same width as the vector element, and the bit is set only if it is true
1899/// for all of the demanded elements in the vector specified by DemandedElts.
1900void computeKnownBits(const Value *V, const APInt &DemandedElts,
                    KnownBits &Known, unsigned Depth, const Query &Q) {
if (!DemandedElts || isa<ScalableVectorType>(V->getType())) {
  // No demanded elts or V is a scalable vector, better to assume we don't
  // know anything.
  Known.resetAll();
  return;
}

assert(V && "No Value?")(static_cast <bool> (V && "No Value?") ? void (
0) : __assert_fail ("V && \"No Value?\"", "llvm/lib/Analysis/ValueTracking.cpp"
, 1909, __extension__ __PRETTY_FUNCTION__));
assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth
 && "Limit Search Depth") ? void (0) : __assert_fail (
"Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1910, __extension__ __PRETTY_FUNCTION__
));

1912#ifndef NDEBUG
Type *Ty = V->getType();
unsigned BitWidth = Known.getBitWidth();

assert((Ty->isIntOrIntVectorTy(BitWidth) || Ty->isPtrOrPtrVectorTy()) &&(static_cast <bool> ((Ty->isIntOrIntVectorTy(BitWidth
) || Ty->isPtrOrPtrVectorTy()) && "Not integer or pointer type!"
) ? void (0) : __assert_fail ("(Ty->isIntOrIntVectorTy(BitWidth) || Ty->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1917, __extension__ __PRETTY_FUNCTION__
))
       "Not integer or pointer type!")(static_cast <bool> ((Ty->isIntOrIntVectorTy(BitWidth
) || Ty->isPtrOrPtrVectorTy()) && "Not integer or pointer type!"
) ? void (0) : __assert_fail ("(Ty->isIntOrIntVectorTy(BitWidth) || Ty->isPtrOrPtrVectorTy()) && \"Not integer or pointer type!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1917, __extension__ __PRETTY_FUNCTION__
));

if (auto *FVTy = dyn_cast<FixedVectorType>(Ty)) {
  assert((static_cast <bool> (FVTy->getNumElements() == DemandedElts
.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements"
) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1922, __extension__ __PRETTY_FUNCTION__
))
      FVTy->getNumElements() == DemandedElts.getBitWidth() &&(static_cast <bool> (FVTy->getNumElements() == DemandedElts
.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements"
) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1922, __extension__ __PRETTY_FUNCTION__
))
      "DemandedElt width should equal the fixed vector number of elements")(static_cast <bool> (FVTy->getNumElements() == DemandedElts
.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements"
) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1922, __extension__ __PRETTY_FUNCTION__
));
} else {
  assert(DemandedElts == APInt(1, 1) &&(static_cast <bool> (DemandedElts == APInt(1, 1) &&
 "DemandedElt width should be 1 for scalars") ? void (0) : __assert_fail
 ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1925, __extension__ __PRETTY_FUNCTION__
))
         "DemandedElt width should be 1 for scalars")(static_cast <bool> (DemandedElts == APInt(1, 1) &&
 "DemandedElt width should be 1 for scalars") ? void (0) : __assert_fail
 ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1925, __extension__ __PRETTY_FUNCTION__
));
}

Type *ScalarTy = Ty->getScalarType();
if (ScalarTy->isPointerTy()) {
  assert(BitWidth == Q.DL.getPointerTypeSizeInBits(ScalarTy) &&(static_cast <bool> (BitWidth == Q.DL.getPointerTypeSizeInBits
(ScalarTy) && "V and Known should have same BitWidth"
) ? void (0) : __assert_fail ("BitWidth == Q.DL.getPointerTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1931, __extension__ __PRETTY_FUNCTION__
))
         "V and Known should have same BitWidth")(static_cast <bool> (BitWidth == Q.DL.getPointerTypeSizeInBits
(ScalarTy) && "V and Known should have same BitWidth"
) ? void (0) : __assert_fail ("BitWidth == Q.DL.getPointerTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1931, __extension__ __PRETTY_FUNCTION__
));
} else {
  assert(BitWidth == Q.DL.getTypeSizeInBits(ScalarTy) &&(static_cast <bool> (BitWidth == Q.DL.getTypeSizeInBits
(ScalarTy) && "V and Known should have same BitWidth"
) ? void (0) : __assert_fail ("BitWidth == Q.DL.getTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1934, __extension__ __PRETTY_FUNCTION__
))
         "V and Known should have same BitWidth")(static_cast <bool> (BitWidth == Q.DL.getTypeSizeInBits
(ScalarTy) && "V and Known should have same BitWidth"
) ? void (0) : __assert_fail ("BitWidth == Q.DL.getTypeSizeInBits(ScalarTy) && \"V and Known should have same BitWidth\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1934, __extension__ __PRETTY_FUNCTION__
));
}
1936#endif

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 = KnownBits::makeConstant(*C);
  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 ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(V)) {
  // We know that CDV must be a vector of integers. Take the intersection of
  // each element.
  Known.Zero.setAllBits(); Known.One.setAllBits();
  for (unsigned i = 0, e = CDV->getNumElements(); i != e; ++i) {
    if (!DemandedElts[i])
      continue;
    APInt Elt = CDV->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) {
    if (!DemandedElts[i])
      continue;
    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!")(static_cast <bool> (!isa<ConstantData>(V) &&
 "Unhandled constant data!") ? void (0) : __assert_fail ("!isa<ConstantData>(V) && \"Unhandled constant data!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 1994, __extension__ __PRETTY_FUNCTION__
));

// All recursive calls that increase depth must come after this.
if (Depth == MaxAnalysisRecursionDepth)
  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, DemandedElts, Known, Depth, Q);

// Aligned pointers have trailing zeros - refine Known.Zero set
if (isa<PointerType>(V->getType())) {
  Align Alignment = V->getPointerAlignment(Q.DL);
  Known.Zero.setLowBits(Log2(Alignment));
}

// 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?")(static_cast <bool> ((Known.Zero & Known.One) == 0 &&
 "Bits known to be one AND zero?") ? void (0) : __assert_fail
 ("(Known.Zero & Known.One) == 0 && \"Bits known to be one AND zero?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2023, __extension__ __PRETTY_FUNCTION__
));
2024}

2026/// Return true if the given value is known to have exactly one
2027/// bit set when defined. For vectors return true if every element is known to
2028/// be a power of two when defined. Supports values with integer or pointer
2029/// types and vectors of integers.
2030bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth,
                          const Query &Q) {
assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth
 && "Limit Search Depth") ? void (0) : __assert_fail (
"Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2032, __extension__ __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++ == MaxAnalysisRecursionDepth)
  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);

// Peek through min/max.
if (match(V, m_MaxOrMin(m_Value(X), m_Value(Y)))) {
  return isKnownToBeAPowerOfTwo(X, OrZero, Depth, Q) &&
         isKnownToBeAPowerOfTwo(Y, 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;
2127}

2129/// Test whether a GEP's result is known to be non-null.
2130///
2131/// Uses properties inherent in a GEP to try to determine whether it is known
2132/// to be non-null.
2133///
2134/// Currently this routine does not support vector GEPs.
2135static 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")(static_cast <bool> (GEP->getType()->isPointerTy(
) && "We only support plain pointer GEP") ? void (0) :
 __assert_fail ("GEP->getType()->isPointerTy() && \"We only support plain pointer GEP\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2146, __extension__ __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()).getKnownMinSize() == 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++ >= MaxAnalysisRecursionDepth)
    continue;

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

return false;
2194}

2196static bool isKnownNonNullFromDominatingCondition(const Value *V,
                                                const Instruction *CtxI,
                                                const DominatorTree *DT) {
if (isa<Constant>(V))
  return false;

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 (const auto *CB = dyn_cast<CallBase>(U))
    if (auto *CalledFunc = CB->getCalledFunction())
      for (const Argument &Arg : CalledFunc->args())
        if (CB->getArgOperand(Arg.getArgNo()) == V &&
            Arg.hasNonNullAttr(/* AllowUndefOrPoison */ false) &&
            DT->dominates(CB, CtxI))
          return true;

  // If the value is used as a load/store, then the pointer must be non null.
  if (V == getLoadStorePointerOperand(U)) {
    const Instruction *I = cast<Instruction>(U);
    if (!NullPointerIsDefined(I->getFunction(),
                              V->getType()->getPointerAddressSpace()) &&
        DT->dominates(I, CtxI))
      return true;
  }

  // Consider only compare instructions uniquely controlling a branch
  Value *RHS;
  CmpInst::Predicate Pred;
  if (!match(U, m_c_ICmp(Pred, m_Specific(V), m_Value(RHS))))
    continue;

  bool NonNullIfTrue;
  if (cmpExcludesZero(Pred, RHS))
    NonNullIfTrue = true;
  else if (cmpExcludesZero(CmpInst::getInversePredicate(Pred), RHS))
    NonNullIfTrue = false;
  else
    continue;

  SmallVector<const User *, 4> WorkList;
  SmallPtrSet<const User *, 4> Visited;
  for (auto *CmpU : U->users()) {
    assert(WorkList.empty() && "Should be!")(static_cast <bool> (WorkList.empty() && "Should be!"
) ? void (0) : __assert_fail ("WorkList.empty() && \"Should be!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2248, __extension__ __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 (NonNullIfTrue)
        if (match(Curr, m_LogicalAnd(m_Value(), m_Value()))) {
          for (auto *CurrU : Curr->users())
            if (Visited.insert(CurrU).second)
              WorkList.push_back(CurrU);
          continue;
        }

      if (const BranchInst *BI = dyn_cast<BranchInst>(Curr)) {
        assert(BI->isConditional() && "uses a comparison!")(static_cast <bool> (BI->isConditional() && "uses a comparison!"
) ? void (0) : __assert_fail ("BI->isConditional() && \"uses a comparison!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2268, __extension__ __PRETTY_FUNCTION__
));

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

return false;
2284}

2286/// Does the 'Range' metadata (which must be a valid MD_range operand list)
2287/// ensure that the value it's attached to is never Value?  'RangeType' is
2288/// is the type of the value described by the range.
2289static bool rangeMetadataExcludesValue(const MDNode* Ranges, const APInt& Value) {
const unsigned NumRanges = Ranges->getNumOperands() / 2;
assert(NumRanges >= 1)(static_cast <bool> (NumRanges >= 1) ? void (0) : __assert_fail
 ("NumRanges >= 1", "llvm/lib/Analysis/ValueTracking.cpp",
 2291, __extension__ __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;
2302}

2304/// Try to detect a recurrence that monotonically increases/decreases from a
2305/// non-zero starting value. These are common as induction variables.
2306static bool isNonZeroRecurrence(const PHINode *PN) {
BinaryOperator *BO = nullptr;
Value *Start = nullptr, *Step = nullptr;
const APInt *StartC, *StepC;
if (!matchSimpleRecurrence(PN, BO, Start, Step) ||
    !match(Start, m_APInt(StartC)) || StartC->isZero())
  return false;

switch (BO->getOpcode()) {
case Instruction::Add:
  // Starting from non-zero and stepping away from zero can never wrap back
  // to zero.
  return BO->hasNoUnsignedWrap() ||
         (BO->hasNoSignedWrap() && match(Step, m_APInt(StepC)) &&
          StartC->isNegative() == StepC->isNegative());
case Instruction::Mul:
  return (BO->hasNoUnsignedWrap() || BO->hasNoSignedWrap()) &&
         match(Step, m_APInt(StepC)) && !StepC->isZero();
case Instruction::Shl:
  return BO->hasNoUnsignedWrap() || BO->hasNoSignedWrap();
case Instruction::AShr:
case Instruction::LShr:
  return BO->isExact();
default:
  return false;
}
2332}

2334/// Return true if the given value is known to be non-zero when defined. For
2335/// vectors, return true if every demanded element is known to be non-zero when
2336/// defined. For pointers, if the context instruction and dominator tree are
2337/// specified, perform context-sensitive analysis and return true if the
2338/// pointer couldn't possibly be null at the specified instruction.
2339/// Supports values with integer or pointer type and vectors of integers.
2340bool isKnownNonZero(const Value *V, const APInt &DemandedElts, unsigned Depth,
                  const Query &Q) {
// FIXME: We currently have no way to represent the DemandedElts of a scalable
// vector
if (isa<ScalableVectorType>(V->getType()))
  return false;

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())
              .getFixedSize() <=
          Q.DL.getTypeSizeInBits(CE->getType()).getFixedSize())
        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<FixedVectorType>(C->getType())) {
    for (unsigned i = 0, e = VecTy->getNumElements(); i != e; ++i) {
      if (!DemandedElts[i])
        continue;
      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;
    }
  }
}

if (isKnownNonZeroFromAssume(V, Q))
  return true;

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

// Check for pointer simplifications.

if (PointerType *PtrTy = dyn_cast<PointerType>(V->getType())) {
  // Alloca never returns null, malloc might.
  if (isa<AllocaInst>(V) && Q.DL.getAllocaAddrSpace() == 0)
    return true;

  // A byval, inalloca may not be null in a non-default addres space. A
  // nonnull argument is assumed never 0.
  if (const Argument *A = dyn_cast<Argument>(V)) {
    if (((A->hasPassPointeeByValueCopyAttr() &&
          !NullPointerIsDefined(A->getParent(), PtrTy->getAddressSpace())) ||
         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);
  }
}

if (isKnownNonNullFromDominatingCondition(V, Q.CxtI, Q.DT))
  return true;

// Check for recursive pointer simplifications.
if (V->getType()->isPointerTy()) {
  // 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))
    return isGEPKnownNonNull(GEP, Depth, Q);

  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()).getFixedSize() <=
        Q.DL.getTypeSizeInBits(I2P->getDestTy()).getFixedSize())
      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()).getFixedSize() <=
      Q.DL.getTypeSizeInBits(P2I->getDestTy()).getFixedSize())
    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, DemandedElts, Depth, Q) ||
         isKnownNonZero(Y, DemandedElts, 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, DemandedElts, 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, DemandedElts, 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, DemandedElts, 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, DemandedElts, Depth, Q);
}
// X + Y.
else if (match(V, m_Add(m_Value(X), m_Value(Y)))) {
  KnownBits XKnown = computeKnownBits(X, DemandedElts, Depth, Q);
  KnownBits YKnown = computeKnownBits(Y, DemandedElts, 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, DemandedElts, Depth, Q) ||
        isKnownNonZero(Y, DemandedElts, 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, DemandedElts, Depth, Q) &&
      isKnownNonZero(Y, DemandedElts, 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(), DemandedElts, Depth, Q) &&
      isKnownNonZero(SI->getFalseValue(), DemandedElts, Depth, Q))
    return true;
}
// PHI
else if (const PHINode *PN = dyn_cast<PHINode>(V)) {
  if (Q.IIQ.UseInstrInfo && isNonZeroRecurrence(PN))
    return true;

  // Check if all incoming values are non-zero using recursion.
  Query RecQ = Q;
  unsigned NewDepth = std::max(Depth, MaxAnalysisRecursionDepth - 1);
  return llvm::all_of(PN->operands(), [&](const Use &U) {
    if (U.get() == PN)
      return true;
    RecQ.CxtI = PN->getIncomingBlock(U)->getTerminator();
    return isKnownNonZero(U.get(), DemandedElts, NewDepth, RecQ);
  });
}
// ExtractElement
else if (const auto *EEI = dyn_cast<ExtractElementInst>(V)) {
  const Value *Vec = EEI->getVectorOperand();
  const Value *Idx = EEI->getIndexOperand();
  auto *CIdx = dyn_cast<ConstantInt>(Idx);
  if (auto *VecTy = dyn_cast<FixedVectorType>(Vec->getType())) {
    unsigned NumElts = VecTy->getNumElements();
    APInt DemandedVecElts = APInt::getAllOnes(NumElts);
    if (CIdx && CIdx->getValue().ult(NumElts))
      DemandedVecElts = APInt::getOneBitSet(NumElts, CIdx->getZExtValue());
    return isKnownNonZero(Vec, DemandedVecElts, Depth, Q);
  }
}
// Freeze
else if (const FreezeInst *FI = dyn_cast<FreezeInst>(V)) {
  auto *Op = FI->getOperand(0);
  if (isKnownNonZero(Op, Depth, Q) &&
      isGuaranteedNotToBePoison(Op, Q.AC, Q.CxtI, Q.DT, Depth))
    return true;
}

KnownBits Known(BitWidth);
computeKnownBits(V, DemandedElts, Known, Depth, Q);
return Known.One != 0;
2612}

2614bool isKnownNonZero(const Value* V, unsigned Depth, const Query& Q) {
// FIXME: We currently have no way to represent the DemandedElts of a scalable
// vector
if (isa<ScalableVectorType>(V->getType()))
  return false;

auto *FVTy = dyn_cast<FixedVectorType>(V->getType());
APInt DemandedElts =
    FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1);
return isKnownNonZero(V, DemandedElts, Depth, Q);
2624}

2626/// If the pair of operators are the same invertible function, return the
2627/// the operands of the function corresponding to each input. Otherwise,
2628/// return None.  An invertible function is one that is 1-to-1 and maps
2629/// every input value to exactly one output value.  This is equivalent to
2630/// saying that Op1 and Op2 are equal exactly when the specified pair of
2631/// operands are equal, (except that Op1 and Op2 may be poison more often.)
2632static Optional<std::pair<Value*, Value*>>
2633getInvertibleOperands(const Operator *Op1,
                    const Operator *Op2) {
if (Op1->getOpcode() != Op2->getOpcode())
  return None;

auto getOperands = [&](unsigned OpNum) -> auto {
  return std::make_pair(Op1->getOperand(OpNum), Op2->getOperand(OpNum));
};

switch (Op1->getOpcode()) {
default:
  break;
case Instruction::Add:
case Instruction::Sub:
  if (Op1->getOperand(0) == Op2->getOperand(0))
    return getOperands(1);
  if (Op1->getOperand(1) == Op2->getOperand(1))
    return getOperands(0);
  break;
case Instruction::Mul: {
  // invertible if A * B == (A * B) mod 2^N where A, and B are integers
  // and N is the bitwdith.  The nsw case is non-obvious, but proven by
  // alive2: https://alive2.llvm.org/ce/z/Z6D5qK
  auto *OBO1 = cast<OverflowingBinaryOperator>(Op1);
  auto *OBO2 = cast<OverflowingBinaryOperator>(Op2);
  if ((!OBO1->hasNoUnsignedWrap() || !OBO2->hasNoUnsignedWrap()) &&
      (!OBO1->hasNoSignedWrap() || !OBO2->hasNoSignedWrap()))
    break;

  // Assume operand order has been canonicalized
  if (Op1->getOperand(1) == Op2->getOperand(1) &&
      isa<ConstantInt>(Op1->getOperand(1)) &&
      !cast<ConstantInt>(Op1->getOperand(1))->isZero())
    return getOperands(0);
  break;
}
case Instruction::Shl: {
  // Same as multiplies, with the difference that we don't need to check
  // for a non-zero multiply. Shifts always multiply by non-zero.
  auto *OBO1 = cast<OverflowingBinaryOperator>(Op1);
  auto *OBO2 = cast<OverflowingBinaryOperator>(Op2);
  if ((!OBO1->hasNoUnsignedWrap() || !OBO2->hasNoUnsignedWrap()) &&
      (!OBO1->hasNoSignedWrap() || !OBO2->hasNoSignedWrap()))
    break;

  if (Op1->getOperand(1) == Op2->getOperand(1))
    return getOperands(0);
  break;
}
case Instruction::AShr:
case Instruction::LShr: {
  auto *PEO1 = cast<PossiblyExactOperator>(Op1);
  auto *PEO2 = cast<PossiblyExactOperator>(Op2);
  if (!PEO1->isExact() || !PEO2->isExact())
    break;

  if (Op1->getOperand(1) == Op2->getOperand(1))
    return getOperands(0);
  break;
}
case Instruction::SExt:
case Instruction::ZExt:
  if (Op1->getOperand(0)->getType() == Op2->getOperand(0)->getType())
    return getOperands(0);
  break;
case Instruction::PHI: {
  const PHINode *PN1 = cast<PHINode>(Op1);
  const PHINode *PN2 = cast<PHINode>(Op2);

  // If PN1 and PN2 are both recurrences, can we prove the entire recurrences
  // are a single invertible function of the start values? Note that repeated
  // application of an invertible function is also invertible
  BinaryOperator *BO1 = nullptr;
  Value *Start1 = nullptr, *Step1 = nullptr;
  BinaryOperator *BO2 = nullptr;
  Value *Start2 = nullptr, *Step2 = nullptr;
  if (PN1->getParent() != PN2->getParent() ||
      !matchSimpleRecurrence(PN1, BO1, Start1, Step1) ||
      !matchSimpleRecurrence(PN2, BO2, Start2, Step2))
    break;

  auto Values = getInvertibleOperands(cast<Operator>(BO1),
                                      cast<Operator>(BO2));
  if (!Values)
     break;

  // We have to be careful of mutually defined recurrences here.  Ex:
  // * X_i = X_(i-1) OP Y_(i-1), and Y_i = X_(i-1) OP V
  // * X_i = Y_i = X_(i-1) OP Y_(i-1)
  // The invertibility of these is complicated, and not worth reasoning
  // about (yet?).
  if (Values->first != PN1 || Values->second != PN2)
    break;

  return std::make_pair(Start1, Start2);
}
}
return None;
2731}

2733/// Return true if V2 == V1 + X, where X is known non-zero.
2734static bool isAddOfNonZero(const Value *V1, const Value *V2, unsigned Depth,
                         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, Depth + 1, Q);
2747}

2749/// Return true if V2 == V1 * C, where V1 is known non-zero, C is not 0/1 and
2750/// the multiplication is nuw or nsw.
2751static bool isNonEqualMul(const Value *V1, const Value *V2, unsigned Depth,
                        const Query &Q) {
if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(V2)) {
  const APInt *C;
  return match(OBO, m_Mul(m_Specific(V1), m_APInt(C))) &&
         (OBO->hasNoUnsignedWrap() || OBO->hasNoSignedWrap()) &&
         !C->isZero() && !C->isOne() && isKnownNonZero(V1, Depth + 1, Q);
}
return false;
2760}

2762/// Return true if V2 == V1 << C, where V1 is known non-zero, C is not 0 and
2763/// the shift is nuw or nsw.
2764static bool isNonEqualShl(const Value *V1, const Value *V2, unsigned Depth,
                        const Query &Q) {
if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(V2)) {
  const APInt *C;
  return match(OBO, m_Shl(m_Specific(V1), m_APInt(C))) &&
         (OBO->hasNoUnsignedWrap() || OBO->hasNoSignedWrap()) &&
         !C->isZero() && isKnownNonZero(V1, Depth + 1, Q);
}
return false;
2773}

2775static bool isNonEqualPHIs(const PHINode *PN1, const PHINode *PN2,
                         unsigned Depth, const Query &Q) {
// Check two PHIs are in same block.
if (PN1->getParent() != PN2->getParent())
  return false;

SmallPtrSet<const BasicBlock *, 8> VisitedBBs;
bool UsedFullRecursion = false;
for (const BasicBlock *IncomBB : PN1->blocks()) {
  if (!VisitedBBs.insert(IncomBB).second)
    continue; // Don't reprocess blocks that we have dealt with already.
  const Value *IV1 = PN1->getIncomingValueForBlock(IncomBB);
  const Value *IV2 = PN2->getIncomingValueForBlock(IncomBB);
  const APInt *C1, *C2;
  if (match(IV1, m_APInt(C1)) && match(IV2, m_APInt(C2)) && *C1 != *C2)
    continue;

  // Only one pair of phi operands is allowed for full recursion.
  if (UsedFullRecursion)
    return false;

  Query RecQ = Q;
  RecQ.CxtI = IncomBB->getTerminator();
  if (!isKnownNonEqual(IV1, IV2, Depth + 1, RecQ))
    return false;
  UsedFullRecursion = true;
}
return true;
2803}

2805/// Return true if it is known that V1 != V2.
2806static bool isKnownNonEqual(const Value *V1, const Value *V2, unsigned Depth,
                          const Query &Q) {
if (V1 == V2)
  return false;
if (V1->getType() != V2->getType())
  // We can't look through casts yet.
  return false;

if (Depth >= MaxAnalysisRecursionDepth)
  return false;

// See if we can recurse through (exactly one of) our operands.  This
// requires our operation be 1-to-1 and map every input value to exactly
// one output value.  Such an operation is invertible.
auto *O1 = dyn_cast<Operator>(V1);
auto *O2 = dyn_cast<Operator>(V2);
if (O1 && O2 && O1->getOpcode() == O2->getOpcode()) {
  if (auto Values = getInvertibleOperands(O1, O2))
    return isKnownNonEqual(Values->first, Values->second, Depth + 1, Q);

  if (const PHINode *PN1 = dyn_cast<PHINode>(V1)) {
    const PHINode *PN2 = cast<PHINode>(V2);
    // FIXME: This is missing a generalization to handle the case where one is
    // a PHI and another one isn't.
    if (isNonEqualPHIs(PN1, PN2, Depth, Q))
      return true;
  };
}

if (isAddOfNonZero(V1, V2, Depth, Q) || isAddOfNonZero(V2, V1, Depth, Q))
  return true;

if (isNonEqualMul(V1, V2, Depth, Q) || isNonEqualMul(V2, V1, Depth, Q))
  return true;

if (isNonEqualShl(V1, V2, Depth, Q) || isNonEqualShl(V2, V1, Depth, 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, Depth, Q);
  KnownBits Known2 = computeKnownBits(V2, Depth, Q);

  if (Known1.Zero.intersects(Known2.One) ||
      Known2.Zero.intersects(Known1.One))
    return true;
}
return false;
2855}

2857/// Return true if 'V & Mask' is known to be zero.  We use this predicate to
2858/// simplify operations downstream. Mask is known to be zero for bits that V
2859/// cannot have.
2860///
2861/// This function is defined on values with integer type, values with pointer
2862/// type, and vectors of integers.  In the case
2863/// where V is a vector, the mask, known zero, and known one values are the
2864/// same width as the vector element, and the bit is set only if it is true
2865/// for all of the elements in the vector.
2866bool 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);
2871}

2873// Match a signed min+max clamp pattern like smax(smin(In, CHigh), CLow).
2874// Returns the input and lower/upper bounds.
2875static bool isSignedMinMaxClamp(const Value *Select, const Value *&In,
                              const APInt *&CLow, const APInt *&CHigh) {
assert(isa<Operator>(Select) &&(static_cast <bool> (isa<Operator>(Select) &&
 cast<Operator>(Select)->getOpcode() == Instruction::
Select && "Input should be a Select!") ? void (0) : __assert_fail
 ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2879, __extension__ __PRETTY_FUNCTION__
))
       cast<Operator>(Select)->getOpcode() == Instruction::Select &&(static_cast <bool> (isa<Operator>(Select) &&
 cast<Operator>(Select)->getOpcode() == Instruction::
Select && "Input should be a Select!") ? void (0) : __assert_fail
 ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2879, __extension__ __PRETTY_FUNCTION__
))
       "Input should be a Select!")(static_cast <bool> (isa<Operator>(Select) &&
 cast<Operator>(Select)->getOpcode() == Instruction::
Select && "Input should be a Select!") ? void (0) : __assert_fail
 ("isa<Operator>(Select) && cast<Operator>(Select)->getOpcode() == Instruction::Select && \"Input should be a Select!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2879, __extension__ __PRETTY_FUNCTION__
));

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

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

const Value *LHS2 = nullptr, *RHS2 = nullptr;
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);
2902}

2904static bool isSignedMinMaxIntrinsicClamp(const IntrinsicInst *II,
                                       const APInt *&CLow,
                                       const APInt *&CHigh) {
assert((II->getIntrinsicID() == Intrinsic::smin ||(static_cast <bool> ((II->getIntrinsicID() == Intrinsic
::smin || II->getIntrinsicID() == Intrinsic::smax) &&
 "Must be smin/smax") ? void (0) : __assert_fail ("(II->getIntrinsicID() == Intrinsic::smin || II->getIntrinsicID() == Intrinsic::smax) && \"Must be smin/smax\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2908, __extension__ __PRETTY_FUNCTION__
))
        II->getIntrinsicID() == Intrinsic::smax) && "Must be smin/smax")(static_cast <bool> ((II->getIntrinsicID() == Intrinsic
::smin || II->getIntrinsicID() == Intrinsic::smax) &&
 "Must be smin/smax") ? void (0) : __assert_fail ("(II->getIntrinsicID() == Intrinsic::smin || II->getIntrinsicID() == Intrinsic::smax) && \"Must be smin/smax\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2908, __extension__ __PRETTY_FUNCTION__
));

Intrinsic::ID InverseID = getInverseMinMaxIntrinsic(II->getIntrinsicID());
auto *InnerII = dyn_cast<IntrinsicInst>(II->getArgOperand(0));
if (!InnerII || InnerII->getIntrinsicID() != InverseID ||
    !match(II->getArgOperand(1), m_APInt(CLow)) ||
    !match(InnerII->getArgOperand(1), m_APInt(CHigh)))
  return false;

if (II->getIntrinsicID() == Intrinsic::smin)
  std::swap(CLow, CHigh);
return CLow->sle(*CHigh);
2920}

2922/// For vector constants, loop over the elements and find the constant with the
2923/// minimum number of sign bits. Return 0 if the value is not a vector constant
2924/// or if any element was not analyzed; otherwise, return the count for the
2925/// element with the minimum number of sign bits.
2926static unsigned computeNumSignBitsVectorConstant(const Value *V,
                                               const APInt &DemandedElts,
                                               unsigned TyBits) {
const auto *CV = dyn_cast<Constant>(V);
if (!CV || !isa<FixedVectorType>(CV->getType()))
  return 0;

unsigned MinSignBits = TyBits;
unsigned NumElts = cast<FixedVectorType>(CV->getType())->getNumElements();
for (unsigned i = 0; i != NumElts; ++i) {
  if (!DemandedElts[i])
    continue;
  // 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;
2947}

2949static unsigned ComputeNumSignBitsImpl(const Value *V,
                                     const APInt &DemandedElts,
                                     unsigned Depth, const Query &Q);

2953static unsigned ComputeNumSignBits(const Value *V, const APInt &DemandedElts,
                                 unsigned Depth, const Query &Q) {
unsigned Result = ComputeNumSignBitsImpl(V, DemandedElts, Depth, Q);
assert(Result > 0 && "At least one sign bit needs to be present!")(static_cast <bool> (Result > 0 && "At least one sign bit needs to be present!"
) ? void (0) : __assert_fail ("Result > 0 && \"At least one sign bit needs to be present!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2956, __extension__ __PRETTY_FUNCTION__
));
return Result;
2958}

2960/// Return the number of times the sign bit of the register is replicated into
2961/// the other bits. We know that at least 1 bit is always equal to the sign bit
2962/// (itself), but other cases can give us information. For example, immediately
2963/// after an "ashr X, 2", we know that the top 3 bits are all equal to each
2964/// other, so we return 3. For vectors, return the number of sign bits for the
2965/// vector element with the minimum number of known sign bits of the demanded
2966/// elements in the vector specified by DemandedElts.
2967static unsigned ComputeNumSignBitsImpl(const Value *V,
                                     const APInt &DemandedElts,
                                     unsigned Depth, const Query &Q) {
Type *Ty = V->getType();

// FIXME: We currently have no way to represent the DemandedElts of a scalable
// vector
if (isa<ScalableVectorType>(Ty))
  return 1;

2977#ifndef NDEBUG
assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth
 && "Limit Search Depth") ? void (0) : __assert_fail (
"Depth <= MaxAnalysisRecursionDepth && \"Limit Search Depth\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2978, __extension__ __PRETTY_FUNCTION__
));

if (auto *FVTy = dyn_cast<FixedVectorType>(Ty)) {
  assert((static_cast <bool> (FVTy->getNumElements() == DemandedElts
.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements"
) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2983, __extension__ __PRETTY_FUNCTION__
))
      FVTy->getNumElements() == DemandedElts.getBitWidth() &&(static_cast <bool> (FVTy->getNumElements() == DemandedElts
.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements"
) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2983, __extension__ __PRETTY_FUNCTION__
))
      "DemandedElt width should equal the fixed vector number of elements")(static_cast <bool> (FVTy->getNumElements() == DemandedElts
.getBitWidth() && "DemandedElt width should equal the fixed vector number of elements"
) ? void (0) : __assert_fail ("FVTy->getNumElements() == DemandedElts.getBitWidth() && \"DemandedElt width should equal the fixed vector number of elements\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2983, __extension__ __PRETTY_FUNCTION__
));
} else {
  assert(DemandedElts == APInt(1, 1) &&(static_cast <bool> (DemandedElts == APInt(1, 1) &&
 "DemandedElt width should be 1 for scalars") ? void (0) : __assert_fail
 ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2986, __extension__ __PRETTY_FUNCTION__
))
         "DemandedElt width should be 1 for scalars")(static_cast <bool> (DemandedElts == APInt(1, 1) &&
 "DemandedElt width should be 1 for scalars") ? void (0) : __assert_fail
 ("DemandedElts == APInt(1, 1) && \"DemandedElt width should be 1 for scalars\""
, "llvm/lib/Analysis/ValueTracking.cpp", 2986, __extension__ __PRETTY_FUNCTION__
));
}
2988#endif

// 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 = Ty->getScalarType();
unsigned TyBits = ScalarTy->isPointerTy() ?
  Q.DL.getPointerTypeSizeInBits(ScalarTy) :
  Q.DL.getTypeSizeInBits(ScalarTy);

unsigned Tmp, Tmp2;
unsigned FirstAnswer = 1;

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

if (Depth == MaxAnalysisRecursionDepth)
  return 1;

if (auto *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: {
    Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);

    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()) {
        // 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();
        Tmp = std::max(Tmp, ResBits);
      }
    }
    return Tmp;
  }

  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).isAllOnes())
          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).isAllOnes())
          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.
    Query RecQ = Q;
    Tmp = TyBits;
    for (unsigned i = 0, e = NumIncomingValues; i != e; ++i) {
      if (Tmp == 1) return Tmp;
      RecQ.CxtI = PN->getIncomingBlock(i)->getTerminator();
      Tmp = std::min(
          Tmp, ComputeNumSignBits(PN->getIncomingValue(i), Depth + 1, RecQ));
    }
    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: {
    // Collect the minimum number of sign bits that are shared by every vector
    // element referenced by the shuffle.
    auto *Shuf = dyn_cast<ShuffleVectorInst>(U);
    if (!Shuf) {
      // FIXME: Add support for shufflevector constant expressions.
      return 1;
    }
    APInt DemandedLHS, DemandedRHS;
    // For undef elements, we don't know anything about the common state of
    // the shuffle result.
    if (!getShuffleDemandedElts(Shuf, DemandedElts, DemandedLHS, DemandedRHS))
      return 1;
    Tmp = std::numeric_limits<unsigned>::max();
    if (!!DemandedLHS) {
      const Value *LHS = Shuf->getOperand(0);
      Tmp = ComputeNumSignBits(LHS, DemandedLHS, Depth + 1, Q);
    }
    // If we don't know anything, early out and try computeKnownBits
    // fall-back.
    if (Tmp == 1)
      break;
    if (!!DemandedRHS) {
      const Value *RHS = Shuf->getOperand(1);
      Tmp2 = ComputeNumSignBits(RHS, DemandedRHS, 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 <= TyBits && "Failed to determine minimum sign bits")(static_cast <bool> (Tmp <= TyBits && "Failed to determine minimum sign bits"
) ? void (0) : __assert_fail ("Tmp <= TyBits && \"Failed to determine minimum sign bits\""
, "llvm/lib/Analysis/ValueTracking.cpp", 3249, __extension__ __PRETTY_FUNCTION__
));
    return Tmp;
  }
  case Instruction::Call: {
    if (const auto *II = dyn_cast<IntrinsicInst>(U)) {
      switch (II->getIntrinsicID()) {
      default: break;
      case Intrinsic::abs:
        Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
        if (Tmp == 1) break;

        // Absolute value reduces number of sign bits by at most 1.
        return Tmp - 1;
      case Intrinsic::smin:
      case Intrinsic::smax: {
        const APInt *CLow, *CHigh;
        if (isSignedMinMaxIntrinsicClamp(II, CLow, CHigh))
          return std::min(CLow->getNumSignBits(), CHigh->getNumSignBits());
      }
      }
    }
  }
  }
}

// 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, DemandedElts, TyBits))
  return VecSignBits;

KnownBits Known(TyBits);
computeKnownBits(V, DemandedElts, 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());
3289}

3291Intrinsic::ID llvm::getIntrinsicForCallSite(const CallBase &CB,
                                          const TargetLibraryInfo *TLI) {
const Function *F = CB.getCalledFunction();
if (!F)
  return Intrinsic::not_intrinsic;

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

// We are going to infer semantics of a library function based on mapping it
// to an LLVM intrinsic. Check that the library function is available from
// this callbase and in this environment.
LibFunc Func;
if (F->hasLocalLinkage() || !TLI || !TLI->getLibFunc(CB, Func) ||
    !CB.onlyReadsMemory())
  return Intrinsic::not_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_roundeven:
case LibFunc_roundevenf:
case LibFunc_roundevenl:
  return Intrinsic::roundeven;
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;
3394}

3396/// Return true if we can prove that the specified FP value is never equal to
3397/// -0.0.
3398/// NOTE: Do not check 'nsz' here because that fast-math-flag does not guarantee
3399///       that a value is not -0.0. It only guarantees that -0.0 may be treated
3400///       the same as +0.0 in floating-point ops.
3401bool llvm::CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI,
                              unsigned Depth) {
if (auto *CFP = dyn_cast<ConstantFP>(V))
  return !CFP->getValueAPF().isNegZero();

if (Depth == MaxAnalysisRecursionDepth)
  return false;

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

// (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);
  case Intrinsic::experimental_constrained_sqrt: {
    // NOTE: This rounding mode restriction may be too strict.
    const auto *CI = cast<ConstrainedFPIntrinsic>(Call);
    if (CI->getRoundingMode() == RoundingMode::NearestTiesToEven)
      return CannotBeNegativeZero(Call->getArgOperand(0), TLI, Depth + 1);
    else
      return false;
  }
  // fabs(x) != -0.0
  case Intrinsic::fabs:
    return true;
  // sitofp and uitofp turn into +0.0 for zero.
  case Intrinsic::experimental_constrained_sitofp:
  case Intrinsic::experimental_constrained_uitofp:
    return true;
  }
}

return false;
3449}

3451/// If \p SignBitOnly is true, test for a known 0 sign bit rather than a
3452/// standard ordered compare. e.g. make -0.0 olt 0.0 be true because of the sign
3453/// bit despite comparing equal.
3454static 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 (auto *CVFVTy = dyn_cast<FixedVectorType>(CV->getType())) {
    unsigned NumElts = CVFVTy->getNumElements();
    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 == MaxAnalysisRecursionDepth)
  return false;

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:
case Instruction::FDiv:
  // X * X is always non-negative or a NaN.
  // X / X is always exactly 1.0 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::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: {
    Value *V0 = I->getOperand(0), *V1 = I->getOperand(1);
    auto isPositiveNum = [&](Value *V) {
      if (SignBitOnly) {
        // With SignBitOnly, this is tricky because the result of
        // maxnum(+0.0, -0.0) is unspecified. Just check if the operand is
        // a constant strictly greater than 0.0.
        const APFloat *C;
        return match(V, m_APFloat(C)) &&
               *C > APFloat::getZero(C->getSemantics());
      }

      // -0.0 compares equal to 0.0, so if this operand is at least -0.0,
      // maxnum can't be ordered-less-than-zero.
      return isKnownNeverNaN(V, TLI) &&
             cannotBeOrderedLessThanZeroImpl(V, TLI, false, Depth + 1);
    };

    // TODO: This could be improved. We could also check that neither operand
    //       has its sign bit set (and at least 1 is not-NAN?).
    return isPositiveNum(V0) || isPositiveNum(V1);
  }

  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;
3615}

3617bool llvm::CannotBeOrderedLessThanZero(const Value *V,
                                     const TargetLibraryInfo *TLI) {
return cannotBeOrderedLessThanZeroImpl(V, TLI, false, 0);
3620}

3622bool llvm::SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI) {
return cannotBeOrderedLessThanZeroImpl(V, TLI, true, 0);
3624}

3626bool llvm::isKnownNeverInfinity(const Value *V, const TargetLibraryInfo *TLI,
                              unsigned Depth) {
assert(V->getType()->isFPOrFPVectorTy() && "Querying for Inf on non-FP type")(static_cast <bool> (V->getType()->isFPOrFPVectorTy
() && "Querying for Inf on non-FP type") ? void (0) :
 __assert_fail ("V->getType()->isFPOrFPVectorTy() && \"Querying for Inf on non-FP type\""
, "llvm/lib/Analysis/ValueTracking.cpp", 3628, __extension__ __PRETTY_FUNCTION__
));

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

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

if (Depth == MaxAnalysisRecursionDepth)
  return false;

if (auto *Inst = dyn_cast<Instruction>(V)) {
  switch (Inst->getOpcode()) {
  case Instruction::Select: {
    return isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1) &&
           isKnownNeverInfinity(Inst->getOperand(2), TLI, Depth + 1);
  }
  case Instruction::SIToFP:
  case Instruction::UIToFP: {
    // Get width of largest magnitude integer (remove a bit if signed).
    // This still works for a signed minimum value because the largest FP
    // value is scaled by some fraction close to 2.0 (1.0 + 0.xxxx).
    int IntSize = Inst->getOperand(0)->getType()->getScalarSizeInBits();
    if (Inst->getOpcode() == Instruction::SIToFP)
      --IntSize;

    // If the exponent of the largest finite FP value can hold the largest
    // integer, the result of the cast must be finite.
    Type *FPTy = Inst->getType()->getScalarType();
    return ilogb(APFloat::getLargest(FPTy->getFltSemantics())) >= IntSize;
  }
  default:
    break;
  }
}

// try to handle fixed width vector constants
auto *VFVTy = dyn_cast<FixedVectorType>(V->getType());
if (VFVTy && isa<Constant>(V)) {
  // For vectors, verify that each element is not infinity.
  unsigned NumElts = VFVTy->getNumElements();
  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->isInfinity())
      return false;
  }
  // All elements were confirmed non-infinity or undefined.
  return true;
}

// was not able to prove that V never contains infinity
return false;
3688}

3690bool llvm::isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI,
                         unsigned Depth) {
assert(V->getType()->isFPOrFPVectorTy() && "Querying for NaN on non-FP type")(static_cast <bool> (V->getType()->isFPOrFPVectorTy
() && "Querying for NaN on non-FP type") ? void (0) :
 __assert_fail ("V->getType()->isFPOrFPVectorTy() && \"Querying for NaN on non-FP type\""
, "llvm/lib/Analysis/ValueTracking.cpp", 3692, __extension__ __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 == MaxAnalysisRecursionDepth)
  return false;

if (auto *Inst = dyn_cast<Instruction>(V)) {
  switch (Inst->getOpcode()) {
  case Instruction::FAdd:
  case Instruction::FSub:
    // Adding positive and negative infinity produces NaN.
    return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1) &&
           isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) &&
           (isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1) ||
            isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1));

  case Instruction::FMul:
    // Zero multiplied with infinity produces NaN.
    // FIXME: If neither side can be zero fmul never produces NaN.
    return isKnownNeverNaN(Inst->getOperand(0), TLI, Depth + 1) &&
           isKnownNeverInfinity(Inst->getOperand(0), TLI, Depth + 1) &&
           isKnownNeverNaN(Inst->getOperand(1), TLI, Depth + 1) &&
           isKnownNeverInfinity(Inst->getOperand(1), TLI, Depth + 1);

  case Instruction::FDiv:
  case Instruction::FRem:
    // FIXME: Only 0/0, Inf/Inf, Inf REM x and x REM 0 produce NaN.
    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:
  case Intrinsic::roundeven:
    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;
  }
}

// Try to handle fixed width vector constants
auto *VFVTy = dyn_cast<FixedVectorType>(V->getType());
if (VFVTy && isa<Constant>(V)) {
  // For vectors, verify that each element is not NaN.
  unsigned NumElts = VFVTy->getNumElements();
  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;
}

// Was not able to prove that V never contains NaN
return false;
3793}

3795Value *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;

// Return Undef for zero-sized type.
if (!DL.getTypeStoreSize(V->getType()).isNonZero())
  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!")(static_cast <bool> (CI->getBitWidth() > 8 &&
 "8 bits should be handled above!") ? void (0) : __assert_fail
 ("CI->getBitWidth() > 8 && \"8 bits should be handled above!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 3845, __extension__ __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) {
    if (auto *PtrTy = dyn_cast<PointerType>(CE->getType())) {
      unsigned BitWidth = DL.getPointerSizeInBits(PtrTy->getAddressSpace());
      return isBytewiseValue(
          ConstantExpr::getIntegerCast(CE->getOperand(0),
                                       Type::getIntNTy(Ctx, BitWidth), 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;
3894}

3896// This is the recursive version of BuildSubAggregate. It takes a few different
3897// arguments. Idxs is the index within the nested struct From that we are
3898// looking at now (which is of type IndexedType). IdxSkip is the number of
3899// indices from Idxs that should be left out when inserting into the resulting
3900// struct. To is the result struct built so far, new insertvalue instructions
3901// build on that.
3902static 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);
3947}

3949// This helper takes a nested struct and extracts a part of it (which is again a
3950// struct) into a new value. For example, given the struct:
3951// { a, { b, { c, d }, e } }
3952// and the indices "1, 1" this returns
3953// { c, d }.
3954//
3955// It does this by inserting an insertvalue for each element in the resulting
3956// struct, as opposed to just inserting a single struct. This will only work if
3957// each of the elements of the substruct are known (ie, inserted into From by an
3958// insertvalue instruction somewhere).
3959//
3960// All inserted insertvalue instructions are inserted before InsertBefore
3961static Value *BuildSubAggregate(Value *From, ArrayRef<unsigned> idx_range,
                              Instruction *InsertBefore) {
assert(InsertBefore && "Must have someplace to insert!")(static_cast <bool> (InsertBefore && "Must have someplace to insert!"
) ? void (0) : __assert_fail ("InsertBefore && \"Must have someplace to insert!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 3963, __extension__ __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);
3971}

3973/// Given an aggregate and a sequence of indices, see if the scalar value
3974/// indexed is already around as a register, for example if it was inserted
3975/// directly into the aggregate.
3976///
3977/// If InsertBefore is not null, this function will duplicate (modified)
3978/// insertvalues when a part of a nested struct is extracted.
3979Value *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()) &&(static_cast <bool> ((V->getType()->isStructTy() ||
 V->getType()->isArrayTy()) && "Not looking at a struct or array?"
) ? void (0) : __assert_fail ("(V->getType()->isStructTy() || V->getType()->isArrayTy()) && \"Not looking at a struct or array?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 3987, __extension__ __PRETTY_FUNCTION__
))
       "Not looking at a struct or array?")(static_cast <bool> ((V->getType()->isStructTy() ||
 V->getType()->isArrayTy()) && "Not looking at a struct or array?"
) ? void (0) : __assert_fail ("(V->getType()->isStructTy() || V->getType()->isArrayTy()) && \"Not looking at a struct or array?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 3987, __extension__ __PRETTY_FUNCTION__
));
assert(ExtractValueInst::getIndexedType(V->getType(), idx_range) &&(static_cast <bool> (ExtractValueInst::getIndexedType(V
->getType(), idx_range) && "Invalid indices for type?"
) ? void (0) : __assert_fail ("ExtractValueInst::getIndexedType(V->getType(), idx_range) && \"Invalid indices for type?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 3989, __extension__ __PRETTY_FUNCTION__
))
       "Invalid indices for type?")(static_cast <bool> (ExtractValueInst::getIndexedType(V
->getType(), idx_range) && "Invalid indices for type?"
) ? void (0) : __assert_fail ("ExtractValueInst::getIndexedType(V->getType(), idx_range) && \"Invalid indices for type?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 3989, __extension__ __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(static_cast <bool> (Idxs.size() == size && "Number of indices added not correct?"
) ? void (0) : __assert_fail ("Idxs.size() == size && \"Number of indices added not correct?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 4054, __extension__ __PRETTY_FUNCTION__
))
         && "Number of indices added not correct?")(static_cast <bool> (Idxs.size() == size && "Number of indices added not correct?"
) ? void (0) : __assert_fail ("Idxs.size() == size && \"Number of indices added not correct?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 4054, __extension__ __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;
4061}

4063bool 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;
4082}

4084bool llvm::getConstantDataArrayInfo(const Value *V,
                                  ConstantDataArraySlice &Slice,
                                  unsigned ElementSize, uint64_t Offset) {
assert(V)(static_cast <bool> (V) ? void (0) : __assert_fail ("V"
, "llvm/lib/Analysis/ValueTracking.cpp", 4087, __extension__ __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).getFixedSize();
    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;
4156}

4158/// This function computes the length of a null-terminated C string pointed to
4159/// by V. If successful, it returns true and returns the string in Str.
4160/// If unsuccessful, it returns false.
4161bool 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;
4193}

4195// These next two are very similar to the above, but also look through PHI
4196// nodes.
4197// TODO: See if we can integrate these two together.

4199/// If we can compute the length of the string pointed to by
4200/// the specified pointer, return 'len+1'.  If we can't, return 0.
4201static 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;
4258}

4260/// If we can compute the length of the string pointed to by
4261/// the specified pointer, return 'len+1'.  If we can't, return 0.
4262uint64_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;
4271}

4273const Value *
4274llvm::getArgumentAliasingToReturnedPointer(const CallBase *Call,
                                         bool MustPreserveNullness) {
assert(Call &&(static_cast <bool> (Call && "getArgumentAliasingToReturnedPointer only works on nonnull calls"
) ? void (0) : __assert_fail ("Call && \"getArgumentAliasingToReturnedPointer only works on nonnull calls\""
, "llvm/lib/Analysis/ValueTracking.cpp", 4277, __extension__ __PRETTY_FUNCTION__
))
       "getArgumentAliasingToReturnedPointer only works on nonnull calls")(static_cast <bool> (Call && "getArgumentAliasingToReturnedPointer only works on nonnull calls"
) ? void (0) : __assert_fail ("Call && \"getArgumentAliasingToReturnedPointer only works on nonnull calls\""
, "llvm/lib/Analysis/ValueTracking.cpp", 4277, __extension__ __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;
4285}

4287bool llvm::isIntrinsicReturningPointerAliasingArgumentWithoutCapturing(
  const CallBase *Call, bool MustPreserveNullness) {
switch (Call->getIntrinsicID()) {
case Intrinsic::launder_invariant_group:
case Intrinsic::strip_invariant_group:
case Intrinsic::aarch64_irg:
case Intrinsic::aarch64_tagp:
  return true;
case Intrinsic::ptrmask:
  return !MustPreserveNullness;
default:
  return false;
}
4300}

4302/// \p PN defines a loop-variant pointer to an object.  Check if the
4303/// previous iteration of the loop was referring to the same object as \p PN.
4304static 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;
4327}

4329const Value *llvm::getUnderlyingObject(const Value *V, unsigned MaxLookup) {
if (!V->getType()->isPointerTy())
  return V;
for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) {
  if (auto *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);
    if (!V->getType()->isPointerTy())
      return V;
  } else if (auto *GA = dyn_cast<GlobalAlias>(V)) {
    if (GA->isInterposable())
      return V;
    V = GA->getAliasee();
  } else {
    if (auto *PHI = dyn_cast<PHINode>(V)) {
      // Look through single-arg phi nodes created by LCSSA.
      if (PHI->getNumIncomingValues() == 1) {
        V = PHI->getIncomingValue(0);
        continue;
      }
    } 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;
      }
    }

    return V;
  }
  assert(V->getType()->isPointerTy() && "Unexpected operand type!")(static_cast <bool> (V->getType()->isPointerTy() &&
 "Unexpected operand type!") ? void (0) : __assert_fail ("V->getType()->isPointerTy() && \"Unexpected operand type!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 4369, __extension__ __PRETTY_FUNCTION__
));
}
return V;
4372}

4374void llvm::getUnderlyingObjects(const Value *V,
                              SmallVectorImpl<const Value *> &Objects,
                              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, 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))
      append_range(Worklist, PN->incoming_values());
    continue;
  }

  Objects.push_back(P);
} while (!Worklist.empty());
4412}

4414/// This is the function that does the work of looking through basic
4415/// ptrtoint+arithmetic+inttoptr sequences.
4416static 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!")(static_cast <bool> (V->getType()->isIntegerTy() &&
 "Unexpected operand type!") ? void (0) : __assert_fail ("V->getType()->isIntegerTy() && \"Unexpected operand type!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 4438, __extension__ __PRETTY_FUNCTION__
));
} while (true);
4440}

4442/// This is a wrapper around getUnderlyingObjects and adds support for basic
4443/// ptrtoint+arithmetic+inttoptr sequences.
4444/// It returns false if unidentified object is found in getUnderlyingObjects.
4445bool llvm::getUnderlyingObjectsForCodeGen(const Value *V,
                                        SmallVectorImpl<Value *> &Objects) {
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);

  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;
4476}

4478AllocaInst *llvm::findAllocaForValue(Value *V, bool OffsetZero) {
AllocaInst *Result = nullptr;
SmallPtrSet<Value *, 4> Visited;
SmallVector<Value *, 4> Worklist;

auto AddWork = [&](Value *V) {
  if (Visited.insert(V).second)
    Worklist.push_back(V);
};

AddWork(V);
do {
  V = Worklist.pop_back_val();
  assert(Visited.count(V))(static_cast <bool> (Visited.count(V)) ? void (0) : __assert_fail
 ("Visited.count(V)", "llvm/lib/Analysis/ValueTracking.cpp", 4491
, __extension__ __PRETTY_FUNCTION__));

  if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
    if (Result && Result != AI)
      return nullptr;
    Result = AI;
  } else if (CastInst *CI = dyn_cast<CastInst>(V)) {
    AddWork(CI->getOperand(0));
  } else if (PHINode *PN = dyn_cast<PHINode>(V)) {
    for (Value *IncValue : PN->incoming_values())
      AddWork(IncValue);
  } else if (auto *SI = dyn_cast<SelectInst>(V)) {
    AddWork(SI->getTrueValue());
    AddWork(SI->getFalseValue());
  } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) {
    if (OffsetZero && !GEP->hasAllZeroIndices())
      return nullptr;
    AddWork(GEP->getPointerOperand());
  } else if (CallBase *CB = dyn_cast<CallBase>(V)) {
    Value *Returned = CB->getReturnedArgOperand();
    if (Returned)
      AddWork(Returned);
    else
      return nullptr;
  } else {
    return nullptr;
  }
} while (!Worklist.empty());

return Result;
4521}

4523static bool onlyUsedByLifetimeMarkersOrDroppableInstsHelper(
  const Value *V, bool AllowLifetime, bool AllowDroppable) {
for (const User *U : V->users()) {
  const IntrinsicInst *II = dyn_cast<IntrinsicInst>(U);
  if (!II)
    return false;

  if (AllowLifetime && II->isLifetimeStartOrEnd())
    continue;

  if (AllowDroppable && II->isDroppable())
    continue;

  return false;
}
return true;
4539}

4541bool llvm::onlyUsedByLifetimeMarkers(const Value *V) {
return onlyUsedByLifetimeMarkersOrDroppableInstsHelper(
    V, /* AllowLifetime */ true, /* AllowDroppable */ false);
4544}
4545bool llvm::onlyUsedByLifetimeMarkersOrDroppableInsts(const Value *V) {
return onlyUsedByLifetimeMarkersOrDroppableInstsHelper(
    V, /* AllowLifetime */ true, /* AllowDroppable */ true);
4548}

4550bool 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);
4559}


4562bool llvm::isSafeToSpeculativelyExecute(const Value *V,
                                      const Instruction *CtxI,
                                      const DominatorTree *DT,
                                      const TargetLibraryInfo *TLI) {
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->isAllOnes())
    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->getAlign(), DL, CtxI, DT,
      TLI);
}
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
}
4645}

4647bool llvm::mayHaveNonDefUseDependency(const Instruction &I) {
if (I.mayReadOrWriteMemory())
  // Memory dependency possible
  return true;
if (!isSafeToSpeculativelyExecute(&I))
  // Can't move above a maythrow call or infinite loop.  Or if an
  // inalloca alloca, above a stacksave call.
  return true;
if (!isGuaranteedToTransferExecutionToSuccessor(&I))
  // 1) Can't reorder two inf-loop calls, even if readonly
  // 2) Also can't reorder an inf-loop call below a instruction which isn't
  //    safe to speculative execute.  (Inverse of above)
  return true;
return false;
4661}

4663/// Convert ConstantRange OverflowResult into ValueTracking OverflowResult.
4664static 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", "llvm/lib/Analysis/ValueTracking.cpp"
, 4675);
4676}

4678/// Combine constant ranges from computeConstantRange() and computeKnownBits().
4679static 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);
4690}

4692OverflowResult 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));
4703}

4705OverflowResult
4706llvm::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;
4746}

4748OverflowResult 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));
4759}

4761static 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;
4822}

4824OverflowResult llvm::computeOverflowForUnsignedSub(const Value *LHS,
                                                 const Value *RHS,
                                                 const DataLayout &DL,
                                                 AssumptionCache *AC,
                                                 const Instruction *CxtI,
                                                 const DominatorTree *DT) {
// Checking for conditions implied by dominating conditions may be expensive.
// Limit it to usub_with_overflow calls for now.
if (match(CxtI,
          m_Intrinsic<Intrinsic::usub_with_overflow>(m_Value(), m_Value())))
  if (auto C =
          isImpliedByDomCondition(CmpInst::ICMP_UGE, LHS, RHS, CxtI, DL)) {
    if (*C)
      return OverflowResult::NeverOverflows;
    return OverflowResult::AlwaysOverflowsLow;
  }
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));
4845}

4847OverflowResult 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));
4864}

4866bool 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")(static_cast <bool> (EVI->getNumIndices() == 1 &&
 "Obvious from CI's type") ? void (0) : __assert_fail ("EVI->getNumIndices() == 1 && \"Obvious from CI's type\""
, "llvm/lib/Analysis/ValueTracking.cpp", 4873, __extension__ __PRETTY_FUNCTION__
));

    if (EVI->getIndices()[0] == 0)
      Results.push_back(EVI);
    else {
      assert(EVI->getIndices()[0] == 1 && "Obvious from CI's type")(static_cast <bool> (EVI->getIndices()[0] == 1 &&
 "Obvious from CI's type") ? void (0) : __assert_fail ("EVI->getIndices()[0] == 1 && \"Obvious from CI's type\""
, "llvm/lib/Analysis/ValueTracking.cpp", 4878, __extension__ __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?")(static_cast <bool> (B->isConditional() && "How else is it using an i1?"
) ? void (0) : __assert_fail ("B->isConditional() && \"How else is it using an i1?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 4882, __extension__ __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);
4914}

4916static bool canCreateUndefOrPoison(const Operator *Op, bool PoisonOnly,
                                 bool ConsiderFlags) {

if (ConsiderFlags && Op->hasPoisonGeneratingFlags())
  return true;

unsigned Opcode = Op->getOpcode();

// Check whether opcode is a poison/undef-generating operation
switch (Opcode) {
case Instruction::Shl:
case Instruction::AShr:
case Instruction::LShr: {
  // Shifts return poison if shiftwidth is larger than the bitwidth.
  if (auto *C = dyn_cast<Constant>(Op->getOperand(1))) {
    SmallVector<Constant *, 4> ShiftAmounts;
    if (auto *FVTy = dyn_cast<FixedVectorType>(C->getType())) {
      unsigned NumElts = FVTy->getNumElements();
      for (unsigned i = 0; i < NumElts; ++i)
        ShiftAmounts.push_back(C->getAggregateElement(i));
    } else if (isa<ScalableVectorType>(C->getType()))
      return true; // Can't tell, just return true to be safe
    else
      ShiftAmounts.push_back(C);

    bool Safe = llvm::all_of(ShiftAmounts, [](Constant *C) {
      auto *CI = dyn_cast_or_null<ConstantInt>(C);
      return CI && CI->getValue().ult(C->getType()->getIntegerBitWidth());
    });
    return !Safe;
  }
  return true;
}
case Instruction::FPToSI:
case Instruction::FPToUI:
  // fptosi/ui yields poison if the resulting value does not fit in the
  // destination type.
  return true;
case Instruction::Call:
  if (auto *II = dyn_cast<IntrinsicInst>(Op)) {
    switch (II->getIntrinsicID()) {
    // TODO: Add more intrinsics.
    case Intrinsic::ctpop:
    case Intrinsic::sadd_with_overflow:
    case Intrinsic::ssub_with_overflow:
    case Intrinsic::smul_with_overflow:
    case Intrinsic::uadd_with_overflow:
    case Intrinsic::usub_with_overflow:
    case Intrinsic::umul_with_overflow:
      return false;
    }
  }
  LLVM_FALLTHROUGH[[gnu::fallthrough]];
case Instruction::CallBr:
case Instruction::Invoke: {
  const auto *CB = cast<CallBase>(Op);
  return !CB->hasRetAttr(Attribute::NoUndef);
}
case Instruction::InsertElement:
case Instruction::ExtractElement: {
  // If index exceeds the length of the vector, it returns poison
  auto *VTy = cast<VectorType>(Op->getOperand(0)->getType());
  unsigned IdxOp = Op->getOpcode() == Instruction::InsertElement ? 2 : 1;
  auto *Idx = dyn_cast<ConstantInt>(Op->getOperand(IdxOp));
  if (!Idx || Idx->getValue().uge(VTy->getElementCount().getKnownMinValue()))
    return true;
  return false;
}
case Instruction::ShuffleVector: {
  // shufflevector may return undef.
  if (PoisonOnly)
    return false;
  ArrayRef<int> Mask = isa<ConstantExpr>(Op)
                           ? cast<ConstantExpr>(Op)->getShuffleMask()
                           : cast<ShuffleVectorInst>(Op)->getShuffleMask();
  return is_contained(Mask, UndefMaskElem);
}
case Instruction::FNeg:
case Instruction::PHI:
case Instruction::Select:
case Instruction::URem:
case Instruction::SRem:
case Instruction::ExtractValue:
case Instruction::InsertValue:
case Instruction::Freeze:
case Instruction::ICmp:
case Instruction::FCmp:
  return false;
case Instruction::GetElementPtr:
  // inbounds is handled above
  // TODO: what about inrange on constexpr?
  return false;
default: {
  const auto *CE = dyn_cast<ConstantExpr>(Op);
  if (isa<CastInst>(Op) || (CE && CE->isCast()))
    return false;
  else if (Instruction::isBinaryOp(Opcode))
    return false;
  // Be conservative and return true.
  return true;
}
}
5018}

5020bool llvm::canCreateUndefOrPoison(const Operator *Op, bool ConsiderFlags) {
return ::canCreateUndefOrPoison(Op, /*PoisonOnly=*/false, ConsiderFlags);
5022}

5024bool llvm::canCreatePoison(const Operator *Op, bool ConsiderFlags) {
return ::canCreateUndefOrPoison(Op, /*PoisonOnly=*/true, ConsiderFlags);
5026}

5028static bool directlyImpliesPoison(const Value *ValAssumedPoison,
                                const Value *V, unsigned Depth) {
if (ValAssumedPoison == V)
  return true;

const unsigned MaxDepth = 2;
if (Depth >= MaxDepth)
  return false;

if (const auto *I = dyn_cast<Instruction>(V)) {
  if (propagatesPoison(cast<Operator>(I)))
    return any_of(I->operands(), [=](const Value *Op) {
      return directlyImpliesPoison(ValAssumedPoison, Op, Depth + 1);
    });

  // 'select ValAssumedPoison, _, _' is poison.
  if (const auto *SI = dyn_cast<SelectInst>(I))
    return directlyImpliesPoison(ValAssumedPoison, SI->getCondition(),
                                 Depth + 1);
  // V  = extractvalue V0, idx
  // V2 = extractvalue V0, idx2
  // V0's elements are all poison or not. (e.g., add_with_overflow)
  const WithOverflowInst *II;
  if (match(I, m_ExtractValue(m_WithOverflowInst(II))) &&
      (match(ValAssumedPoison, m_ExtractValue(m_Specific(II))) ||
       llvm::is_contained(II->args(), ValAssumedPoison)))
    return true;
}
return false;
5057}

5059static bool impliesPoison(const Value *ValAssumedPoison, const Value *V,
                        unsigned Depth) {
if (isGuaranteedNotToBeUndefOrPoison(ValAssumedPoison))
  return true;

if (directlyImpliesPoison(ValAssumedPoison, V, /* Depth */ 0))
  return true;

const unsigned MaxDepth = 2;
if (Depth >= MaxDepth)
  return false;

const auto *I = dyn_cast<Instruction>(ValAssumedPoison);
if (I && !canCreatePoison(cast<Operator>(I))) {
  return all_of(I->operands(), [=](const Value *Op) {
    return impliesPoison(Op, V, Depth + 1);
  });
}
return false;
5078}

5080bool llvm::impliesPoison(const Value *ValAssumedPoison, const Value *V) {
return ::impliesPoison(ValAssumedPoison, V, /* Depth */ 0);
5082}

5084static bool programUndefinedIfUndefOrPoison(const Value *V,
                                          bool PoisonOnly);

5087static bool isGuaranteedNotToBeUndefOrPoison(const Value *V,
                                           AssumptionCache *AC,
                                           const Instruction *CtxI,
                                           const DominatorTree *DT,
                                           unsigned Depth, bool PoisonOnly) {
if (Depth >= MaxAnalysisRecursionDepth)
  return false;

if (isa<MetadataAsValue>(V))
  return false;

if (const auto *A = dyn_cast<Argument>(V)) {
  if (A->hasAttribute(Attribute::NoUndef))
    return true;
}

if (auto *C = dyn_cast<Constant>(V)) {
  if (isa<UndefValue>(C))
    return PoisonOnly && !isa<PoisonValue>(C);

  if (isa<ConstantInt>(C) || isa<GlobalVariable>(C) || isa<ConstantFP>(V) ||
      isa<ConstantPointerNull>(C) || isa<Function>(C))
    return true;

  if (C->getType()->isVectorTy() && !isa<ConstantExpr>(C))
    return (PoisonOnly ? !C->containsPoisonElement()
                       : !C->containsUndefOrPoisonElement()) &&
           !C->containsConstantExpression();
}

// Strip cast operations from a pointer value.
// Note that stripPointerCastsSameRepresentation can strip off getelementptr
// inbounds with zero offset. To guarantee that the result isn't poison, the
// stripped pointer is checked as it has to be pointing into an allocated
// object or be null `null` to ensure `inbounds` getelement pointers with a
// zero offset could not produce poison.
// It can strip off addrspacecast that do not change bit representation as
// well. We believe that such addrspacecast is equivalent to no-op.
auto *StrippedV = V->stripPointerCastsSameRepresentation();
if (isa<AllocaInst>(StrippedV) || isa<GlobalVariable>(StrippedV) ||
    isa<Function>(StrippedV) || isa<ConstantPointerNull>(StrippedV))
  return true;

auto OpCheck = [&](const Value *V) {
  return isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth + 1,
                                          PoisonOnly);
};

if (auto *Opr = dyn_cast<Operator>(V)) {
  // If the value is a freeze instruction, then it can never
  // be undef or poison.
  if (isa<FreezeInst>(V))
    return true;

  if (const auto *CB = dyn_cast<CallBase>(V)) {
    if (CB->hasRetAttr(Attribute::NoUndef))
      return true;
  }

  if (const auto *PN = dyn_cast<PHINode>(V)) {
    unsigned Num = PN->getNumIncomingValues();
    bool IsWellDefined = true;
    for (unsigned i = 0; i < Num; ++i) {
      auto *TI = PN->getIncomingBlock(i)->getTerminator();
      if (!isGuaranteedNotToBeUndefOrPoison(PN->getIncomingValue(i), AC, TI,
                                            DT, Depth + 1, PoisonOnly)) {
        IsWellDefined = false;
        break;
      }
    }
    if (IsWellDefined)
      return true;
  } else if (!canCreateUndefOrPoison(Opr) && all_of(Opr->operands(), OpCheck))
    return true;
}

if (auto *I = dyn_cast<LoadInst>(V))
  if (I->getMetadata(LLVMContext::MD_noundef))
    return true;

if (programUndefinedIfUndefOrPoison(V, PoisonOnly))
  return true;

// CxtI may be null or a cloned instruction.
if (!CtxI || !CtxI->getParent() || !DT)
  return false;

auto *DNode = DT->getNode(CtxI->getParent());
if (!DNode)
  // Unreachable block
  return false;

// If V is used as a branch condition before reaching CtxI, V cannot be
// undef or poison.
//   br V, BB1, BB2
// BB1:
//   CtxI ; V cannot be undef or poison here
auto *Dominator = DNode->getIDom();
while (Dominator) {
  auto *TI = Dominator->getBlock()->getTerminator();

  Value *Cond = nullptr;
  if (auto BI = dyn_cast_or_null<BranchInst>(TI)) {
    if (BI->isConditional())
      Cond = BI->getCondition();
  } else if (auto SI = dyn_cast_or_null<SwitchInst>(TI)) {
    Cond = SI->getCondition();
  }

  if (Cond) {
    if (Cond == V)
      return true;
    else if (PoisonOnly && isa<Operator>(Cond)) {
      // For poison, we can analyze further
      auto *Opr = cast<Operator>(Cond);
      if (propagatesPoison(Opr) && is_contained(Opr->operand_values(), V))
        return true;
    }
  }

  Dominator = Dominator->getIDom();
}

if (getKnowledgeValidInContext(V, {Attribute::NoUndef}, CtxI, DT, AC))
  return true;

return false;
5214}

5216bool llvm::isGuaranteedNotToBeUndefOrPoison(const Value *V, AssumptionCache *AC,
                                          const Instruction *CtxI,
                                          const DominatorTree *DT,
                                          unsigned Depth) {
return ::isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth, false);
5221}

5223bool llvm::isGuaranteedNotToBePoison(const Value *V, AssumptionCache *AC,
                                   const Instruction *CtxI,
                                   const DominatorTree *DT, unsigned Depth) {
return ::isGuaranteedNotToBeUndefOrPoison(V, AC, CtxI, DT, Depth, true);
5227}

5229OverflowResult 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);
5236}

5238OverflowResult 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);
5245}

5247bool 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 (isa<ReturnInst>(I))
  return false;
if (isa<UnreachableInst>(I))
  return false;

// Note: Do not add new checks here; instead, change Instruction::mayThrow or
// Instruction::willReturn.
//
// FIXME: Move this check into Instruction::willReturn.
if (isa<CatchPadInst>(I)) {
  switch (classifyEHPersonality(I->getFunction()->getPersonalityFn())) {
  default:
    // A catchpad may invoke exception object constructors and such, which
    // in some languages can be arbitrary code, so be conservative by default.
    return false;
  case EHPersonality::CoreCLR:
    // For CoreCLR, it just involves a type test.
    return true;
  }
}

// An instruction that returns without throwing must transfer control flow
// to a successor.
return !I->mayThrow() && I->willReturn();
5277}

5279bool llvm::isGuaranteedToTransferExecutionToSuccessor(const BasicBlock *BB) {
// TODO: This is slightly conservative for invoke instruction since exiting
// via an exception *is* normal control for them.
for (const Instruction &I : *BB)
  if (!isGuaranteedToTransferExecutionToSuccessor(&I))
    return false;
return true;
5286}

5288bool llvm::isGuaranteedToTransferExecutionToSuccessor(
 BasicBlock::const_iterator Begin, BasicBlock::const_iterator End,
 unsigned ScanLimit) {
return isGuaranteedToTransferExecutionToSuccessor(make_range(Begin, End),
                                                  ScanLimit);
5293}

5295bool llvm::isGuaranteedToTransferExecutionToSuccessor(
 iterator_range<BasicBlock::const_iterator> Range, unsigned ScanLimit) {
assert(ScanLimit && "scan limit must be non-zero")(static_cast <bool> (ScanLimit && "scan limit must be non-zero"
) ? void (0) : __assert_fail ("ScanLimit && \"scan limit must be non-zero\""
, "llvm/lib/Analysis/ValueTracking.cpp", 5297, __extension__ __PRETTY_FUNCTION__
));
for (const Instruction &I : Range) {
  if (isa<DbgInfoIntrinsic>(I))
      continue;
  if (--ScanLimit == 0)
    return false;
  if (!isGuaranteedToTransferExecutionToSuccessor(&I))
    return false;
}
return true;
5307}

5309bool 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."
, "llvm/lib/Analysis/ValueTracking.cpp", 5321);
5322}

5324bool llvm::propagatesPoison(const Operator *I) {
switch (I->getOpcode()) {
case Instruction::Freeze:
case Instruction::Select:
case Instruction::PHI:
case Instruction::Invoke:
  return false;
case Instruction::Call:
  if (auto *II = dyn_cast<IntrinsicInst>(I)) {
    switch (II->getIntrinsicID()) {
    // TODO: Add more intrinsics.
    case Intrinsic::sadd_with_overflow:
    case Intrinsic::ssub_with_overflow:
    case Intrinsic::smul_with_overflow:
    case Intrinsic::uadd_with_overflow:
    case Intrinsic::usub_with_overflow:
    case Intrinsic::umul_with_overflow:
      // If an input is a vector containing a poison element, the
      // two output vectors (calculated results, overflow bits)'
      // corresponding lanes are poison.
      return true;
    case Intrinsic::ctpop:
      return true;
    }
  }
  return false;
case Instruction::ICmp:
case Instruction::FCmp:
case Instruction::GetElementPtr:
  return true;
default:
  if (isa<BinaryOperator>(I) || isa<UnaryOperator>(I) || isa<CastInst>(I))
    return true;

  // Be conservative and return false.
  return false;
}
5361}

5363void llvm::getGuaranteedWellDefinedOps(
  const Instruction *I, SmallPtrSetImpl<const Value *> &Operands) {
switch (I->getOpcode()) {
  case Instruction::Store:
    Operands.insert(cast<StoreInst>(I)->getPointerOperand());
    break;

  case Instruction::Load:
    Operands.insert(cast<LoadInst>(I)->getPointerOperand());
    break;

  // Since dereferenceable attribute imply noundef, atomic operations
  // also implicitly have noundef pointers too
  case Instruction::AtomicCmpXchg:
    Operands.insert(cast<AtomicCmpXchgInst>(I)->getPointerOperand());
    break;

  case Instruction::AtomicRMW:
    Operands.insert(cast<AtomicRMWInst>(I)->getPointerOperand());
    break;

  case Instruction::Call:
  case Instruction::Invoke: {
    const CallBase *CB = cast<CallBase>(I);
    if (CB->isIndirectCall())
      Operands.insert(CB->getCalledOperand());
    for (unsigned i = 0; i < CB->arg_size(); ++i) {
      if (CB->paramHasAttr(i, Attribute::NoUndef) ||
          CB->paramHasAttr(i, Attribute::Dereferenceable))
        Operands.insert(CB->getArgOperand(i));
    }
    break;
  }
  case Instruction::Ret:
    if (I->getFunction()->hasRetAttribute(Attribute::NoUndef))
      Operands.insert(I->getOperand(0));
    break;
  default:
    break;
}
5403}

5405void llvm::getGuaranteedNonPoisonOps(const Instruction *I,
                                   SmallPtrSetImpl<const Value *> &Operands) {
getGuaranteedWellDefinedOps(I, Operands);
switch (I->getOpcode()) {
// Divisors of these operations are allowed to be partially undef.
case Instruction::UDiv:
case Instruction::SDiv:
case Instruction::URem:
case Instruction::SRem:
  Operands.insert(I->getOperand(1));
  break;
case Instruction::Switch:
  if (BranchOnPoisonAsUB)
    Operands.insert(cast<SwitchInst>(I)->getCondition());
  break;
case Instruction::Br: {
  auto *BR = cast<BranchInst>(I);
  if (BranchOnPoisonAsUB && BR->isConditional())
    Operands.insert(BR->getCondition());
  break;
}
default:
  break;
}
5429}

5431bool llvm::mustTriggerUB(const Instruction *I,
                       const SmallSet<const Value *, 16>& KnownPoison) {
SmallPtrSet<const Value *, 4> NonPoisonOps;
getGuaranteedNonPoisonOps(I, NonPoisonOps);

for (const auto *V : NonPoisonOps)
  if (KnownPoison.count(V))
    return true;

return false;
5441}

5443static bool programUndefinedIfUndefOrPoison(const Value *V,
                                          bool PoisonOnly) {
// We currently only look for uses of values within the same basic
// block, as that makes it easier to guarantee that the uses will be
// executed given that Inst 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 = nullptr;
BasicBlock::const_iterator Begin;
if (const auto *Inst = dyn_cast<Instruction>(V)) {
  BB = Inst->getParent();
  Begin = Inst->getIterator();
  Begin++;
} else if (const auto *Arg = dyn_cast<Argument>(V)) {
  BB = &Arg->getParent()->getEntryBlock();
  Begin = BB->begin();
} else {
  return false;
}

// Limit number of instructions we look at, to avoid scanning through large
// blocks. The current limit is chosen arbitrarily.
unsigned ScanLimit = 32;
BasicBlock::const_iterator End = BB->end();

if (!PoisonOnly) {
  // Since undef does not propagate eagerly, be conservative & just check
  // whether a value is directly passed to an instruction that must take
  // well-defined operands.

  for (auto &I : make_range(Begin, End)) {
    if (isa<DbgInfoIntrinsic>(I))
      continue;
    if (--ScanLimit == 0)
      break;

    SmallPtrSet<const Value *, 4> WellDefinedOps;
    getGuaranteedWellDefinedOps(&I, WellDefinedOps);
    if (WellDefinedOps.contains(V))
      return true;

    if (!isGuaranteedToTransferExecutionToSuccessor(&I))
      break;
  }
  return false;
}

// Set of instructions that we have proved will yield poison if Inst
// does.
SmallSet<const Value *, 16> YieldsPoison;
SmallSet<const BasicBlock *, 4> Visited;

YieldsPoison.insert(V);
auto Propagate = [&](const User *User) {
  if (propagatesPoison(cast<Operator>(User)))
    YieldsPoison.insert(User);
};
for_each(V->users(), Propagate);
Visited.insert(BB);

while (true) {
  for (auto &I : make_range(Begin, End)) {
    if (isa<DbgInfoIntrinsic>(I))
      continue;
    if (--ScanLimit == 0)
      return false;
    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_each(I.users(), Propagate);
  }

  BB = BB->getSingleSuccessor();
  if (!BB || !Visited.insert(BB).second)
    break;

  Begin = BB->getFirstNonPHI()->getIterator();
  End = BB->end();
}
return false;
5529}

5531bool llvm::programUndefinedIfUndefOrPoison(const Instruction *Inst) {
return ::programUndefinedIfUndefOrPoison(Inst, false);
5533}

5535bool llvm::programUndefinedIfPoison(const Instruction *Inst) {
return ::programUndefinedIfUndefOrPoison(Inst, true);
5537}

5539static 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;
}

if (isa<ConstantAggregateZero>(V))
  return true;

return false;
5560}

5562static 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;
5577}

5579/// Match clamp pattern for float types without care about NaNs or signed zeros.
5580/// Given non-min/max outer cmp/select from the clamp pattern this
5581/// function recognizes if it can be substitued by a "canonical" min/max
5582/// pattern.
5583static 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 < *FC2)
    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 > *FC2)
    return {SPF_FMINNUM, SPNB_RETURNS_ANY, false};
  break;
default:
  break;
}

return {SPF_UNKNOWN, SPNB_NA, false};
5633}

5635/// Recognize variations of:
5636///   CLAMP(v,l,h) ==> ((v) < (l) ? (l) : ((v) > (h) ? (h) : (v)))
5637static 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};
5669}

5671/// Recognize variations of:
5672///   a < c ? min(a,b) : min(b,c) ==> min(min(a,b),min(b,c))
5673static 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")(static_cast <bool> (CmpInst::isIntPredicate(Pred) &&
 "Expected integer comparison") ? void (0) : __assert_fail ("CmpInst::isIntPredicate(Pred) && \"Expected integer comparison\""
, "llvm/lib/Analysis/ValueTracking.cpp", 5678, __extension__ __PRETTY_FUNCTION__
));

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

Value *C = nullptr, *D = nullptr;
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};
5764}

5766/// If the input value is the result of a 'not' op, constant integer, or vector
5767/// splat of a constant integer, return the bitwise-not source value.
5768/// TODO: This could be extended to handle non-splat vector integer constants.
5769static Value *getNotValue(Value *V) {
Value *NotV;
if (match(V, m_Not(m_Value(NotV))))
  return NotV;

const APInt *C;
if (match(V, m_APInt(C)))
  return ConstantInt::get(V->getType(), ~(*C));

return nullptr;
5779}

5781/// Match non-obvious integer minimum and maximum sequences.
5782static 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;

// Look through 'not' ops to find disguised min/max.
// (X > Y) ? ~X : ~Y ==> (~X < ~Y) ? ~X : ~Y ==> MIN(~X, ~Y)
// (X < Y) ? ~X : ~Y ==> (~X > ~Y) ? ~X : ~Y ==> MAX(~X, ~Y)
if (CmpLHS == getNotValue(TrueVal) && CmpRHS == getNotValue(FalseVal)) {
  switch (Pred) {
  case CmpInst::ICMP_SGT: return {SPF_SMIN, SPNB_NA, false};
  case CmpInst::ICMP_SLT: return {SPF_SMAX, SPNB_NA, false};
  case CmpInst::ICMP_UGT: return {SPF_UMIN, SPNB_NA, false};
  case CmpInst::ICMP_ULT: return {SPF_UMAX, SPNB_NA, false};
  default: break;
  }
}

// (X > Y) ? ~Y : ~X ==> (~X < ~Y) ? ~Y : ~X ==> MAX(~Y, ~X)
// (X < Y) ? ~Y : ~X ==> (~X > ~Y) ? ~Y : ~X ==> MIN(~Y, ~X)
if (CmpLHS == getNotValue(FalseVal) && CmpRHS == getNotValue(TrueVal)) {
  switch (Pred) {
  case CmpInst::ICMP_SGT: return {SPF_SMAX, SPNB_NA, false};
  case CmpInst::ICMP_SLT: return {SPF_SMIN, SPNB_NA, false};
  case CmpInst::ICMP_UGT: return {SPF_UMAX, SPNB_NA, false};
  case CmpInst::ICMP_ULT: return {SPF_UMIN, SPNB_NA, false};
  default: break;
  }
}

if (Pred != CmpInst::ICMP_SGT && Pred != CmpInst::ICMP_SLT)
  return {SPF_UNKNOWN, 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->isZero() && 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->isAllOnes() && C2->isMinSignedValue())
    return {CmpLHS == FalseVal ? SPF_UMAX : SPF_UMIN, SPNB_NA, false};
}

return {SPF_UNKNOWN, SPNB_NA, false};
5849}

5851bool llvm::isKnownNegation(const Value *X, const Value *Y, bool NeedNSW) {
assert(X && Y && "Invalid operand")(static_cast <bool> (X && Y && "Invalid operand"
) ? void (0) : __assert_fail ("X && Y && \"Invalid operand\""
, "llvm/lib/Analysis/ValueTracking.cpp", 5852, __extension__ __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)))));
5870}

5872static 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)->containsUndefOrPoisonElement())
    OutputZeroVal = TrueVal;
  else if (match(FalseVal, m_AnyZeroFP()) && !match(TrueVal, m_AnyZeroFP()) &&
           !cast<Constant>(FalseVal)->containsUndefOrPoisonElement())
    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);
6053}

6055/// Helps to match a select pattern in case of a type mismatch.
6056///
6057/// The function processes the case when type of true and false values of a
6058/// select instruction differs from type of the cmp instruction operands because
6059/// of a cast instruction. The function checks if it is legal to move the cast
6060/// operation after "select". If yes, it returns the new second value of
6061/// "select" (with the assumption that cast is moved):
6062/// 1. As operand of cast instruction when both values of "select" are same cast
6063/// instructions.
6064/// 2. As restored constant (by applying reverse cast operation) when the first
6065/// value of the "select" is a cast operation and the second value is a
6066/// constant.
6067/// NOTE: We return only the new second value because the first value could be
6068/// accessed as operand of cast instruction.
6069static 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;
6160}

6162SelectPatternResult llvm::matchSelectPattern(Value *V, Value *&LHS, Value *&RHS,
                                           Instruction::CastOps *CastOp,
                                           unsigned Depth) {
if (Depth >= MaxAnalysisRecursionDepth)
  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);
6179}

6181SelectPatternResult 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);
6218}

6220CmpInst::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!", "llvm/lib/Analysis/ValueTracking.cpp"
, 6229);
6230}

6232SelectPatternFlavor 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!", "llvm/lib/Analysis/ValueTracking.cpp"
, 6237);
6238}

6240Intrinsic::ID llvm::getInverseMinMaxIntrinsic(Intrinsic::ID MinMaxID) {
switch (MinMaxID) {
case Intrinsic::smax: return Intrinsic::smin;
case Intrinsic::smin: return Intrinsic::smax;
case Intrinsic::umax: return Intrinsic::umin;
case Intrinsic::umin: return Intrinsic::umax;
default: llvm_unreachable("Unexpected intrinsic")::llvm::llvm_unreachable_internal("Unexpected intrinsic", "llvm/lib/Analysis/ValueTracking.cpp"
, 6246);
}
6248}

6250CmpInst::Predicate llvm::getInverseMinMaxPred(SelectPatternFlavor SPF) {
return getMinMaxPred(getInverseMinMaxFlavor(SPF));
6252}

6254APInt llvm::getMinMaxLimit(SelectPatternFlavor SPF, unsigned BitWidth) {
switch (SPF) {
case SPF_SMAX: return APInt::getSignedMaxValue(BitWidth);
case SPF_SMIN: return APInt::getSignedMinValue(BitWidth);
case SPF_UMAX: return APInt::getMaxValue(BitWidth);
case SPF_UMIN: return APInt::getMinValue(BitWidth);
default: llvm_unreachable("Unexpected flavor")::llvm::llvm_unreachable_internal("Unexpected flavor", "llvm/lib/Analysis/ValueTracking.cpp"
, 6260);
}
6262}

6264std::pair<Intrinsic::ID, bool>
6265llvm::canConvertToMinOrMaxIntrinsic(ArrayRef<Value *> VL) {
// Check if VL contains select instructions that can be folded into a min/max
// vector intrinsic and return the intrinsic if it is possible.
// TODO: Support floating point min/max.
bool AllCmpSingleUse = true;
SelectPatternResult SelectPattern;
SelectPattern.Flavor = SPF_UNKNOWN;
if (all_of(VL, [&SelectPattern, &AllCmpSingleUse](Value *I) {
      Value *LHS, *RHS;
      auto CurrentPattern = matchSelectPattern(I, LHS, RHS);
      if (!SelectPatternResult::isMinOrMax(CurrentPattern.Flavor) ||
          CurrentPattern.Flavor == SPF_FMINNUM ||
          CurrentPattern.Flavor == SPF_FMAXNUM ||
          !I->getType()->isIntOrIntVectorTy())
        return false;
      if (SelectPattern.Flavor != SPF_UNKNOWN &&
          SelectPattern.Flavor != CurrentPattern.Flavor)
        return false;
      SelectPattern = CurrentPattern;
      AllCmpSingleUse &=
          match(I, m_Select(m_OneUse(m_Value()), m_Value(), m_Value()));
      return true;
    })) {
  switch (SelectPattern.Flavor) {
  case SPF_SMIN:
    return {Intrinsic::smin, AllCmpSingleUse};
  case SPF_UMIN:
    return {Intrinsic::umin, AllCmpSingleUse};
  case SPF_SMAX:
    return {Intrinsic::smax, AllCmpSingleUse};
  case SPF_UMAX:
    return {Intrinsic::umax, AllCmpSingleUse};
  default:
    llvm_unreachable("unexpected select pattern flavor")::llvm::llvm_unreachable_internal("unexpected select pattern flavor"
, "llvm/lib/Analysis/ValueTracking.cpp", 6298);
  }
}
return {Intrinsic::not_intrinsic, false};
6302}

6304bool llvm::matchSimpleRecurrence(const PHINode *P, BinaryOperator *&BO,
                               Value *&Start, Value *&Step) {
// 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)
  return false;

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();

  switch (Opcode) {
  default:
    continue;
  // TODO: Expand list -- xor, div, gep, uaddo, etc..
  case Instruction::LShr:
  case Instruction::AShr:
  case Instruction::Shl:
  case Instruction::Add:
  case Instruction::Sub:
  case Instruction::And:
  case Instruction::Or:
  case Instruction::Mul: {
    Value *LL = LU->getOperand(0);
    Value *LR = LU->getOperand(1);
    // Find a recurrence.
    if (LL == P)
      L = LR;
    else if (LR == P)
      L = LL;
    else
      continue; // Check for recurrence with L and R flipped.

    break; // Match!
  }
  };

  // We have matched a recurrence of the form:
  //   %iv = [R, %entry], [%iv.next, %backedge]
  //   %iv.next = binop %iv, L
  // OR
  //   %iv = [R, %entry], [%iv.next, %backedge]
  //   %iv.next = binop L, %iv
  BO = cast<BinaryOperator>(LU);
  Start = R;
  Step = L;
  return true;
}
return false;
6358}

6360bool llvm::matchSimpleRecurrence(const BinaryOperator *I, PHINode *&P,
                               Value *&Start, Value *&Step) {
BinaryOperator *BO = nullptr;
P = dyn_cast<PHINode>(I->getOperand(0));
if (!P)
  P = dyn_cast<PHINode>(I->getOperand(1));
return P && matchSimpleRecurrence(P, BO, Start, Step) && BO == I;
6367}

6369/// Return true if "icmp Pred LHS RHS" is always true.
6370static 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!")(static_cast <bool> (!LHS->getType()->isVectorTy(
) && "TODO: extend to handle vectors!") ? void (0) : __assert_fail
 ("!LHS->getType()->isVectorTy() && \"TODO: extend to handle vectors!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6373, __extension__ __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;
}
}
6426}

6428/// Return true if "icmp Pred BLHS BRHS" is true whenever "icmp Pred
6429/// ALHS ARHS" is true.  Otherwise, return None.
6430static Optional<bool>
6431isImpliedCondOperands(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;
}
6452}

6454/// Return true if the operands of the two compares match.  IsSwappedOps is true
6455/// when the operands match, but are swapped.
6456static 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;
6463}

6465/// Return true if "icmp1 APred X, Y" implies "icmp2 BPred X, Y" is true.
6466/// Return false if "icmp1 APred X, Y" implies "icmp2 BPred X, Y" is false.
6467/// Otherwise, return None if we can't infer anything.
6468static 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;
6481}

6483/// Return true if "icmp APred X, C1" implies "icmp BPred X, C2" is true.
6484/// Return false if "icmp APred X, C1" implies "icmp BPred X, C2" is false.
6485/// Otherwise, return None if we can't infer anything.
6486static Optional<bool>
6487isImpliedCondMatchingImmOperands(CmpInst::Predicate APred,
                               const ConstantInt *C1,
                               CmpInst::Predicate BPred,
                               const ConstantInt *C2) {
ConstantRange DomCR =
    ConstantRange::makeExactICmpRegion(APred, C1->getValue());
ConstantRange CR = ConstantRange::makeExactICmpRegion(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;
6501}

6503/// Return true if LHS implies RHS is true.  Return false if LHS implies RHS is
6504/// false.  Otherwise, return None if we can't infer anything.
6505static Optional<bool> isImpliedCondICmps(const ICmpInst *LHS,
                                       CmpInst::Predicate BPred,
                                       const Value *BLHS, const Value *BRHS,
                                       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.
CmpInst::Predicate APred =
    LHSIsTrue ? LHS->getPredicate() : LHS->getInversePredicate();

// 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;
6543}

6545/// Return true if LHS implies RHS is true.  Return false if LHS implies RHS is
6546/// false.  Otherwise, return None if we can't infer anything.  We expect the
6547/// RHS to be an icmp and the LHS to be an 'and', 'or', or a 'select' instruction.
6548static Optional<bool>
6549isImpliedCondAndOr(const Instruction *LHS, CmpInst::Predicate RHSPred,
                 const Value *RHSOp0, const Value *RHSOp1,
                 const DataLayout &DL, bool LHSIsTrue, unsigned Depth) {
// The LHS must be an 'or', 'and', or a 'select' instruction.
assert((LHS->getOpcode() == Instruction::And ||(static_cast <bool> ((LHS->getOpcode() == Instruction
::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode
() == Instruction::Select) && "Expected LHS to be 'and', 'or', or 'select'."
) ? void (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6556, __extension__ __PRETTY_FUNCTION__
))
        LHS->getOpcode() == Instruction::Or ||(static_cast <bool> ((LHS->getOpcode() == Instruction
::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode
() == Instruction::Select) && "Expected LHS to be 'and', 'or', or 'select'."
) ? void (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6556, __extension__ __PRETTY_FUNCTION__
))
        LHS->getOpcode() == Instruction::Select) &&(static_cast <bool> ((LHS->getOpcode() == Instruction
::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode
() == Instruction::Select) && "Expected LHS to be 'and', 'or', or 'select'."
) ? void (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6556, __extension__ __PRETTY_FUNCTION__
))
       "Expected LHS to be 'and', 'or', or 'select'.")(static_cast <bool> ((LHS->getOpcode() == Instruction
::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode
() == Instruction::Select) && "Expected LHS to be 'and', 'or', or 'select'."
) ? void (0) : __assert_fail ("(LHS->getOpcode() == Instruction::And || LHS->getOpcode() == Instruction::Or || LHS->getOpcode() == Instruction::Select) && \"Expected LHS to be 'and', 'or', or 'select'.\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6556, __extension__ __PRETTY_FUNCTION__
));

assert(Depth <= MaxAnalysisRecursionDepth && "Hit recursion limit")(static_cast <bool> (Depth <= MaxAnalysisRecursionDepth
 && "Hit recursion limit") ? void (0) : __assert_fail
 ("Depth <= MaxAnalysisRecursionDepth && \"Hit recursion limit\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6558, __extension__ __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.
const Value *ALHS, *ARHS;
if ((!LHSIsTrue && match(LHS, m_LogicalOr(m_Value(ALHS), m_Value(ARHS)))) ||
    (LHSIsTrue && match(LHS, m_LogicalAnd(m_Value(ALHS), m_Value(ARHS))))) {
  // FIXME: Make this non-recursion.
  if (Optional<bool> Implication = isImpliedCondition(
          ALHS, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, Depth + 1))
    return Implication;
  if (Optional<bool> Implication = isImpliedCondition(
          ARHS, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue, Depth + 1))
    return Implication;
  return None;
}
return None;
6576}

6578Optional<bool>
6579llvm::isImpliedCondition(const Value *LHS, CmpInst::Predicate RHSPred,
                       const Value *RHSOp0, const Value *RHSOp1,
                       const DataLayout &DL, bool LHSIsTrue, unsigned Depth) {
// Bail out when we hit the limit.
if (Depth == MaxAnalysisRecursionDepth)
  return None;

// A mismatch occurs when we compare a scalar cmp to a vector cmp, for
// example.
if (RHSOp0->getType()->isVectorTy() != LHS->getType()->isVectorTy())
  return None;

Type *OpTy = LHS->getType();
assert(OpTy->isIntOrIntVectorTy(1) && "Expected integer type only!")(static_cast <bool> (OpTy->isIntOrIntVectorTy(1) &&
 "Expected integer type only!") ? void (0) : __assert_fail ("OpTy->isIntOrIntVectorTy(1) && \"Expected integer type only!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6592, __extension__ __PRETTY_FUNCTION__
));

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

assert(OpTy->isIntegerTy(1) && "implied by above")(static_cast <bool> (OpTy->isIntegerTy(1) &&
 "implied by above") ? void (0) : __assert_fail ("OpTy->isIntegerTy(1) && \"implied by above\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6598, __extension__ __PRETTY_FUNCTION__
));

// Both LHS and RHS are icmps.
const ICmpInst *LHSCmp = dyn_cast<ICmpInst>(LHS);
if (LHSCmp)
  return isImpliedCondICmps(LHSCmp, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue,
                            Depth);

/// The LHS should be an 'or', 'and', or a 'select' instruction.  We expect
/// the RHS to be an icmp.
/// FIXME: Add support for and/or/select on the RHS.
if (const Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
  if ((LHSI->getOpcode() == Instruction::And ||
       LHSI->getOpcode() == Instruction::Or ||
       LHSI->getOpcode() == Instruction::Select))
    return isImpliedCondAndOr(LHSI, RHSPred, RHSOp0, RHSOp1, DL, LHSIsTrue,
                              Depth);
}
return None;
6617}

6619Optional<bool> llvm::isImpliedCondition(const Value *LHS, const Value *RHS,
                                      const DataLayout &DL, bool LHSIsTrue,
                                      unsigned Depth) {
// LHS ==> RHS by definition
if (LHS == RHS)
  return LHSIsTrue;

const ICmpInst *RHSCmp = dyn_cast<ICmpInst>(RHS);
if (RHSCmp)
  return isImpliedCondition(LHS, RHSCmp->getPredicate(),
                            RHSCmp->getOperand(0), RHSCmp->getOperand(1), DL,
                            LHSIsTrue, Depth);
return None;
6632}

6634// Returns a pair (Condition, ConditionIsTrue), where Condition is a branch
6635// condition dominating ContextI or nullptr, if no condition is found.
6636static std::pair<Value *, bool>
6637getDomPredecessorCondition(const Instruction *ContextI) {
if (!ContextI || !ContextI->getParent())
  return {nullptr, false};

// 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 {nullptr, false};

// 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 {nullptr, false};

// The branch should get simplified. Don't bother simplifying this condition.
if (TrueBB == FalseBB)
  return {nullptr, false};

assert((TrueBB == ContextBB || FalseBB == ContextBB) &&(static_cast <bool> ((TrueBB == ContextBB || FalseBB ==
 ContextBB) && "Predecessor block does not point to successor?"
) ? void (0) : __assert_fail ("(TrueBB == ContextBB || FalseBB == ContextBB) && \"Predecessor block does not point to successor?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6659, __extension__ __PRETTY_FUNCTION__
))
       "Predecessor block does not point to successor?")(static_cast <bool> ((TrueBB == ContextBB || FalseBB ==
 ContextBB) && "Predecessor block does not point to successor?"
) ? void (0) : __assert_fail ("(TrueBB == ContextBB || FalseBB == ContextBB) && \"Predecessor block does not point to successor?\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6659, __extension__ __PRETTY_FUNCTION__
));

// Is this condition implied by the predecessor condition?
return {PredCond, TrueBB == ContextBB};
6663}

6665Optional<bool> llvm::isImpliedByDomCondition(const Value *Cond,
                                           const Instruction *ContextI,
                                           const DataLayout &DL) {
assert(Cond->getType()->isIntOrIntVectorTy(1) && "Condition must be bool")(static_cast <bool> (Cond->getType()->isIntOrIntVectorTy
(1) && "Condition must be bool") ? void (0) : __assert_fail
 ("Cond->getType()->isIntOrIntVectorTy(1) && \"Condition must be bool\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6668, __extension__ __PRETTY_FUNCTION__
));
auto PredCond = getDomPredecessorCondition(ContextI);
if (PredCond.first)
  return isImpliedCondition(PredCond.first, Cond, DL, PredCond.second);
return None;
6673}

6675Optional<bool> llvm::isImpliedByDomCondition(CmpInst::Predicate Pred,
                                           const Value *LHS, const Value *RHS,
                                           const Instruction *ContextI,
                                           const DataLayout &DL) {
auto PredCond = getDomPredecessorCondition(ContextI);
if (PredCond.first)
  return isImpliedCondition(PredCond.first, Pred, LHS, RHS, DL,
                            PredCond.second);
return None;
6684}

6686static void setLimitsForBinOp(const BinaryOperator &BO, APInt &Lower,
                            APInt &Upper, const InstrInfoQuery &IIQ,
                            bool PreferSignedRange) {
unsigned Width = Lower.getBitWidth();
const APInt *C;
switch (BO.getOpcode()) {
case Instruction::Add:
  if (match(BO.getOperand(1), m_APInt(C)) && !C->isZero()) {
    bool HasNSW = IIQ.hasNoSignedWrap(&BO);
    bool HasNUW = IIQ.hasNoUnsignedWrap(&BO);

    // If the caller expects a signed compare, then try to use a signed range.
    // Otherwise if both no-wraps are set, use the unsigned range because it
    // is never larger than the signed range. Example:
    // "add nuw nsw i8 X, -2" is unsigned [254,255] vs. signed [-128, 125].
    if (PreferSignedRange && HasNSW && HasNUW)
      HasNUW = false;

    if (HasNUW) {
      // 'add nuw x, C' produces [C, UINT_MAX].
      Lower = *C;
    } else if (HasNSW) {
      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->isZero() && 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::getAllOnes(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->isZero() && 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->isAllOnes()) {
      // '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!")(static_cast <bool> (Upper != Lower && "Upper part of range has wrapped!"
) ? void (0) : __assert_fail ("Upper != Lower && \"Upper part of range has wrapped!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6807, __extension__ __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->isZero()) {
    // '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;
}
6849}

6851static void setLimitsForIntrinsic(const IntrinsicInst &II, APInt &Lower,
                                APInt &Upper) {
unsigned Width = Lower.getBitWidth();
const APInt *C;
switch (II.getIntrinsicID()) {
case Intrinsic::ctpop:
case Intrinsic::ctlz:
case Intrinsic::cttz:
  // Maximum of set/clear bits is the bit width.
  assert(Lower == 0 && "Expected lower bound to be zero")(static_cast <bool> (Lower == 0 && "Expected lower bound to be zero"
) ? void (0) : __assert_fail ("Lower == 0 && \"Expected lower bound to be zero\""
, "llvm/lib/Analysis/ValueTracking.cpp", 6860, __extension__ __PRETTY_FUNCTION__
));
  Upper = Width + 1;
  break;
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;
case Intrinsic::umin:
case Intrinsic::umax:
case Intrinsic::smin:
case Intrinsic::smax:
  if (!match(II.getOperand(0), m_APInt(C)) &&
      !match(II.getOperand(1), m_APInt(C)))
    break;

  switch (II.getIntrinsicID()) {
  case Intrinsic::umin:
    Upper = *C + 1;
    break;
  case Intrinsic::umax:
    Lower = *C;
    break;
  case Intrinsic::smin:
    Lower = APInt::getSignedMinValue(Width);
    Upper = *C + 1;
    break;
  case Intrinsic::smax:
    Lower = *C;
    Upper = APInt::getSignedMaxValue(Width) + 1;
    break;
  default:
    llvm_unreachable("Must be min/max intrinsic")::llvm::llvm_unreachable_internal("Must be min/max intrinsic"
, "llvm/lib/Analysis/ValueTracking.cpp", 6938);
  }
  break;
case Intrinsic::abs:
  // If abs of SIGNED_MIN is poison, then the result is [0..SIGNED_MAX],
  // otherwise it is [0..SIGNED_MIN], as -SIGNED_MIN == SIGNED_MIN.
  if (match(II.getOperand(1), m_One()))
    Upper = APInt::getSignedMaxValue(Width) + 1;
  else
    Upper = APInt::getSignedMinValue(Width) + 1;
  break;
default:
  break;
}
6952}

6954static void setLimitsForSelectPattern(const SelectInst &SI, APInt &Lower,
                                    APInt &Upper, const InstrInfoQuery &IIQ) {
const Value *LHS = nullptr, *RHS = nullptr;
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::getZero(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;
}
7005}

7007static void setLimitForFPToI(const Instruction *I, APInt &Lower, APInt &Upper) {
// The maximum representable value of a half is 65504. For floats the maximum
// value is 3.4e38 which requires roughly 129 bits.
unsigned BitWidth = I->getType()->getScalarSizeInBits();
if (!I->getOperand(0)->getType()->getScalarType()->isHalfTy())
  return;
if (isa<FPToSIInst>(I) && BitWidth >= 17) {
  Lower = APInt(BitWidth, -65504);
  Upper = APInt(BitWidth, 65505);
}

if (isa<FPToUIInst>(I) && BitWidth >= 16) {
  // For a fptoui the lower limit is left as 0.
  Upper = APInt(BitWidth, 65505);
}
7022}

7024ConstantRange llvm::computeConstantRange(const Value *V, bool ForSigned,
                                       bool UseInstrInfo, AssumptionCache *AC,
                                       const Instruction *CtxI,
                                       const DominatorTree *DT,
                                       unsigned Depth) {
assert(V->getType()->isIntOrIntVectorTy() && "Expected integer instruction")(static_cast <bool> (V->getType()->isIntOrIntVectorTy
() && "Expected integer instruction") ? void (0) : __assert_fail
 ("V->getType()->isIntOrIntVectorTy() && \"Expected integer instruction\""
, "llvm/lib/Analysis/ValueTracking.cpp", 7029, __extension__ __PRETTY_FUNCTION__
));

if (Depth == MaxAnalysisRecursionDepth)
  return ConstantRange::getFull(V->getType()->getScalarSizeInBits());

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, ForSigned);
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);
else if (isa<FPToUIInst>(V) || isa<FPToSIInst>(V))
  setLimitForFPToI(cast<Instruction>(V), Lower, Upper);

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));

if (CtxI && AC) {
  // Try to restrict the range based on information from assumptions.
  for (auto &AssumeVH : AC->assumptionsFor(V)) {
    if (!AssumeVH)
      continue;
    CallInst *I = cast<CallInst>(AssumeVH);
    assert(I->getParent()->getParent() == CtxI->getParent()->getParent() &&(static_cast <bool> (I->getParent()->getParent() ==
 CtxI->getParent()->getParent() && "Got assumption for the wrong function!"
) ? void (0) : __assert_fail ("I->getParent()->getParent() == CtxI->getParent()->getParent() && \"Got assumption for the wrong function!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 7064, __extension__ __PRETTY_FUNCTION__
))
           "Got assumption for the wrong function!")(static_cast <bool> (I->getParent()->getParent() ==
 CtxI->getParent()->getParent() && "Got assumption for the wrong function!"
) ? void (0) : __assert_fail ("I->getParent()->getParent() == CtxI->getParent()->getParent() && \"Got assumption for the wrong function!\""
, "llvm/lib/Analysis/ValueTracking.cpp", 7064, __extension__ __PRETTY_FUNCTION__
));
    assert(I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume &&(static_cast <bool> (I->getCalledFunction()->getIntrinsicID
() == Intrinsic::assume && "must be an assume intrinsic"
) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\""
, "llvm/lib/Analysis/ValueTracking.cpp", 7066, __extension__ __PRETTY_FUNCTION__
))
           "must be an assume intrinsic")(static_cast <bool> (I->getCalledFunction()->getIntrinsicID
() == Intrinsic::assume && "must be an assume intrinsic"
) ? void (0) : __assert_fail ("I->getCalledFunction()->getIntrinsicID() == Intrinsic::assume && \"must be an assume intrinsic\""
, "llvm/lib/Analysis/ValueTracking.cpp", 7066, __extension__ __PRETTY_FUNCTION__
));

    if (!isValidAssumeForContext(I, CtxI, DT))
      continue;
    Value *Arg = I->getArgOperand(0);
    ICmpInst *Cmp = dyn_cast<ICmpInst>(Arg);
    // Currently we just use information from comparisons.
    if (!Cmp || Cmp->getOperand(0) != V)
      continue;
    // TODO: Set "ForSigned" parameter via Cmp->isSigned()?
    ConstantRange RHS =
        computeConstantRange(Cmp->getOperand(1), /* ForSigned */ false,
                             UseInstrInfo, AC, I, DT, Depth + 1);
    CR = CR.intersectWith(
        ConstantRange::makeAllowedICmpRegion(Cmp->getPredicate(), RHS));
  }
}

return CR;
7085}

7087static Optional<int64_t>
7088getOffsetFromIndex(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 fixed-length
  // vector. Multiply the index by the ElementSize.
  TypeSize Size = DL.getTypeAllocSize(GTI.getIndexedType());
  if (Size.isScalable())
    return None;
  Offset += Size.getFixedSize() * OpC->getSExtValue();
}

return Offset;
7118}

7120Optional<int64_t> llvm::isPointerOffset(const Value *Ptr1, const Value *Ptr2,
                                      const DataLayout &DL) {
APInt Offset1(DL.getIndexTypeSizeInBits(Ptr1->getType()), 0);
APInt Offset2(DL.getIndexTypeSizeInBits(Ptr2->getType()), 0);
Ptr1 = Ptr1->stripAndAccumulateConstantOffsets(DL, Offset1, true);
Ptr2 = Ptr2->stripAndAccumulateConstantOffsets(DL, Offset2, true);

// Handle the trivial case first.
if (Ptr1 == Ptr2)
  return Offset2.getSExtValue() - Offset1.getSExtValue();

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

// 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) ||
    GEP1->getSourceElementType() != GEP2->getSourceElementType())
  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 IOffset1 = getOffsetFromIndex(GEP1, Idx, DL);
auto IOffset2 = getOffsetFromIndex(GEP2, Idx, DL);
if (!IOffset1 || !IOffset2)
  return None;
return *IOffset2 - *IOffset1 + Offset2.getSExtValue() -
       Offset1.getSExtValue();
7155}