/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/lib/AST/ExprConstant.cpp

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//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the Expr constant evaluator.
//
// Constant expression evaluation produces four main results:
//
//  * A success/failure flag indicating whether constant folding was successful.
//    This is the 'bool' return value used by most of the code in this file. A
//    'false' return value indicates that constant folding has failed, and any
//    appropriate diagnostic has already been produced.
//
//  * An evaluated result, valid only if constant folding has not failed.
//
//  * A flag indicating if evaluation encountered (unevaluated) side-effects.
//    These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1),
//    where it is possible to determine the evaluated result regardless.
//
//  * A set of notes indicating why the evaluation was not a constant expression
//    (under the C++11 / C++1y rules only, at the moment), or, if folding failed
//    too, why the expression could not be folded.
//
// If we are checking for a potential constant expression, failure to constant
// fold a potential constant sub-expression will be indicated by a 'false'
// return value (the expression could not be folded) and no diagnostic (the
// expression is not necessarily non-constant).
//
//===----------------------------------------------------------------------===//

#include "Interp/Context.h"
#include "Interp/Frame.h"
#include "Interp/State.h"
#include "clang/AST/APValue.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTDiagnostic.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/Attr.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/CurrentSourceLocExprScope.h"
#include "clang/AST/Expr.h"
#include "clang/AST/OSLog.h"
#include "clang/AST/OptionalDiagnostic.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/AST/TypeLoc.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/APFixedPoint.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/raw_ostream.h"
#include <cstring>
#include <functional>

#define DEBUG_TYPE "exprconstant"

using namespace clang;
using llvm::APFixedPoint;
using llvm::APInt;
using llvm::APSInt;
using llvm::APFloat;
using llvm::FixedPointSemantics;
using llvm::Optional;

namespace {
  struct LValue;
  class CallStackFrame;
  class EvalInfo;

  using SourceLocExprScopeGuard =
      CurrentSourceLocExprScope::SourceLocExprScopeGuard;

  static QualType getType(APValue::LValueBase B) {
    return B.getType();
  }

  /// Get an LValue path entry, which is known to not be an array index, as a
  /// field declaration.
  static const FieldDecl *getAsField(APValue::LValuePathEntry E) {
    return dyn_cast_or_null<FieldDecl>(E.getAsBaseOrMember().getPointer());
  }
  /// Get an LValue path entry, which is known to not be an array index, as a
  /// base class declaration.
  static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) {
    return dyn_cast_or_null<CXXRecordDecl>(E.getAsBaseOrMember().getPointer());
  }
  /// Determine whether this LValue path entry for a base class names a virtual
  /// base class.
  static bool isVirtualBaseClass(APValue::LValuePathEntry E) {
    return E.getAsBaseOrMember().getInt();
  }

  /// Given an expression, determine the type used to store the result of
  /// evaluating that expression.
  static QualType getStorageType(const ASTContext &Ctx, const Expr *E) {
    if (E->isPRValue())
      return E->getType();
    return Ctx.getLValueReferenceType(E->getType());
  }

  /// Given a CallExpr, try to get the alloc_size attribute. May return null.
  static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) {
    if (const FunctionDecl *DirectCallee = CE->getDirectCallee())
      return DirectCallee->getAttr<AllocSizeAttr>();
    if (const Decl *IndirectCallee = CE->getCalleeDecl())
      return IndirectCallee->getAttr<AllocSizeAttr>();
    return nullptr;
  }

  /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr.
  /// This will look through a single cast.
  ///
  /// Returns null if we couldn't unwrap a function with alloc_size.
  static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) {
    if (!E->getType()->isPointerType())
      return nullptr;

    E = E->IgnoreParens();
    // If we're doing a variable assignment from e.g. malloc(N), there will
    // probably be a cast of some kind. In exotic cases, we might also see a
    // top-level ExprWithCleanups. Ignore them either way.
    if (const auto *FE = dyn_cast<FullExpr>(E))
      E = FE->getSubExpr()->IgnoreParens();

    if (const auto *Cast = dyn_cast<CastExpr>(E))
      E = Cast->getSubExpr()->IgnoreParens();

    if (const auto *CE = dyn_cast<CallExpr>(E))
      return getAllocSizeAttr(CE) ? CE4.35k : nullptr598;
    return nullptr;
  }

  /// Determines whether or not the given Base contains a call to a function
  /// with the alloc_size attribute.
  static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) {
    const auto *E = Base.dyn_cast<const Expr *>();
    return E && E->getType()->isPointerType()49.1k && tryUnwrapAllocSizeCall(E)2.62k;
  }

  /// Determines whether the given kind of constant expression is only ever
  /// used for name mangling. If so, it's permitted to reference things that we
  /// can't generate code for (in particular, dllimported functions).
  static bool isForManglingOnly(ConstantExprKind Kind) {
    switch (Kind) {
    case ConstantExprKind::Normal:
    case ConstantExprKind::ClassTemplateArgument:
    case ConstantExprKind::ImmediateInvocation:
      // Note that non-type template arguments of class type are emitted as
      // template parameter objects.
      return false;

    case ConstantExprKind::NonClassTemplateArgument:
      return true;
    }
    llvm_unreachable("unknown ConstantExprKind");
  }

  static bool isTemplateArgument(ConstantExprKind Kind) {
    switch (Kind) {
    case ConstantExprKind::Normal:
    case ConstantExprKind::ImmediateInvocation:
      return false;

    case ConstantExprKind::ClassTemplateArgument:
    case ConstantExprKind::NonClassTemplateArgument:
      return true;
    }
    llvm_unreachable("unknown ConstantExprKind");
  }

  /// The bound to claim that an array of unknown bound has.
  /// The value in MostDerivedArraySize is undefined in this case. So, set it
  /// to an arbitrary value that's likely to loudly break things if it's used.
  static const uint64_t AssumedSizeForUnsizedArray =
      std::numeric_limits<uint64_t>::max() / 2;

  /// Determines if an LValue with the given LValueBase will have an unsized
  /// array in its designator.
  /// Find the path length and type of the most-derived subobject in the given
  /// path, and find the size of the containing array, if any.
  static unsigned
  findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
                           ArrayRef<APValue::LValuePathEntry> Path,
                           uint64_t &ArraySize, QualType &Type, bool &IsArray,
                           bool &FirstEntryIsUnsizedArray) {
    // This only accepts LValueBases from APValues, and APValues don't support
    // arrays that lack size info.
    assert(!isBaseAnAllocSizeCall(Base) &&
           "Unsized arrays shouldn't appear here");
    unsigned MostDerivedLength = 0;
    Type = getType(Base);

    for (unsigned I = 0, N = Path.size(); I != N; ++I67.8k) {
      if (Type->isArrayType()) {
        const ArrayType *AT = Ctx.getAsArrayType(Type);
        Type = AT->getElementType();
        MostDerivedLength = I + 1;
        IsArray = true;

        if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
          ArraySize = CAT->getSize().getZExtValue();
        } else {
          assert(I == 0 && "unexpected unsized array designator");
          FirstEntryIsUnsizedArray = true;
          ArraySize = AssumedSizeForUnsizedArray;
        }
      } else if (21.1kType->isAnyComplexType()21.1k) {
        const ComplexType *CT = Type->castAs<ComplexType>();
        Type = CT->getElementType();
        ArraySize = 2;
        MostDerivedLength = I + 1;
        IsArray = true;
      } else if (const FieldDecl *FD = getAsField(Path[I])) {
        Type = FD->getType();
        ArraySize = 0;
        MostDerivedLength = I + 1;
        IsArray = false;
      } else {
        // Path[I] describes a base class.
        ArraySize = 0;
        IsArray = false;
      }
    }
    return MostDerivedLength;
  }

  /// A path from a glvalue to a subobject of that glvalue.
  struct SubobjectDesignator {
    /// True if the subobject was named in a manner not supported by C++11. Such
    /// lvalues can still be folded, but they are not core constant expressions
    /// and we cannot perform lvalue-to-rvalue conversions on them.
    unsigned Invalid : 1;

    /// Is this a pointer one past the end of an object?
    unsigned IsOnePastTheEnd : 1;

    /// Indicator of whether the first entry is an unsized array.
    unsigned FirstEntryIsAnUnsizedArray : 1;

    /// Indicator of whether the most-derived object is an array element.
    unsigned MostDerivedIsArrayElement : 1;

    /// The length of the path to the most-derived object of which this is a
    /// subobject.
    unsigned MostDerivedPathLength : 28;

    /// The size of the array of which the most-derived object is an element.
    /// This will always be 0 if the most-derived object is not an array
    /// element. 0 is not an indicator of whether or not the most-derived object
    /// is an array, however, because 0-length arrays are allowed.
    ///
    /// If the current array is an unsized array, the value of this is
    /// undefined.
    uint64_t MostDerivedArraySize;

    /// The type of the most derived object referred to by this address.
    QualType MostDerivedType;

    typedef APValue::LValuePathEntry PathEntry;

    /// The entries on the path from the glvalue to the designated subobject.
    SmallVector<PathEntry, 8> Entries;

    SubobjectDesignator() : Invalid(true) {}

    explicit SubobjectDesignator(QualType T)
        : Invalid(false), IsOnePastTheEnd(false),
          FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
          MostDerivedPathLength(0), MostDerivedArraySize(0),
          MostDerivedType(T) {}

    SubobjectDesignator(ASTContext &Ctx, const APValue &V)
        : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false),
          FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
          MostDerivedPathLength(0), MostDerivedArraySize(0) {
      assert(V.isLValue() && "Non-LValue used to make an LValue designator?");
      if (!Invalid) {
        IsOnePastTheEnd = V.isLValueOnePastTheEnd();
        ArrayRef<PathEntry> VEntries = V.getLValuePath();
        Entries.insert(Entries.end(), VEntries.begin(), VEntries.end());
        if (V.getLValueBase()) {
          bool IsArray = false;
          bool FirstIsUnsizedArray = false;
          MostDerivedPathLength = findMostDerivedSubobject(
              Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
              MostDerivedType, IsArray, FirstIsUnsizedArray);
          MostDerivedIsArrayElement = IsArray;
          FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
        }
      }
    }

    void truncate(ASTContext &Ctx, APValue::LValueBase Base,
                  unsigned NewLength) {
      if (Invalid)
        return;

      assert(Base && "cannot truncate path for null pointer");
      assert(NewLength <= Entries.size() && "not a truncation");

      if (NewLength == Entries.size())
        return;
      Entries.resize(NewLength);

      bool IsArray = false;
      bool FirstIsUnsizedArray = false;
      MostDerivedPathLength = findMostDerivedSubobject(
          Ctx, Base, Entries, MostDerivedArraySize, MostDerivedType, IsArray,
          FirstIsUnsizedArray);
      MostDerivedIsArrayElement = IsArray;
      FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
    }

    void setInvalid() {
      Invalid = true;
      Entries.clear();
    }

    /// Determine whether the most derived subobject is an array without a
    /// known bound.
    bool isMostDerivedAnUnsizedArray() const {
      assert(!Invalid && "Calling this makes no sense on invalid designators");
      return Entries.size() == 1 && FirstEntryIsAnUnsizedArray540k;
    }

    /// Determine what the most derived array's size is. Results in an assertion
    /// failure if the most derived array lacks a size.
    uint64_t getMostDerivedArraySize() const {
      assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size");
      return MostDerivedArraySize;
    }

    /// Determine whether this is a one-past-the-end pointer.
    bool isOnePastTheEnd() const {
      assert(!Invalid);
      if (IsOnePastTheEnd)
        return true;
      if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement2.00M &&
          Entries[MostDerivedPathLength - 1].getAsArrayIndex() ==
              MostDerivedArraySize)
        return true;
      return false;
    }

    /// Get the range of valid index adjustments in the form
    ///   {maximum value that can be subtracted from this pointer,
    ///    maximum value that can be added to this pointer}
    std::pair<uint64_t, uint64_t> validIndexAdjustments() {
      if (Invalid || isMostDerivedAnUnsizedArray())
        return {0, 0};

      // [expr.add]p4: For the purposes of these operators, a pointer to a
      // nonarray object behaves the same as a pointer to the first element of
      // an array of length one with the type of the object as its element type.
      bool IsArray = MostDerivedPathLength == Entries.size() &&
                     MostDerivedIsArrayElement2.10k;
      uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()2.05k
                                    : (uint64_t)IsOnePastTheEnd136;
      uint64_t ArraySize =
          IsArray ? getMostDerivedArraySize()2.05k : (uint64_t)1136;
      return {ArrayIndex, ArraySize - ArrayIndex};
    }

    /// Check that this refers to a valid subobject.
    bool isValidSubobject() const {
      if (Invalid)
        return false;
      return !isOnePastTheEnd();
    }
    /// Check that this refers to a valid subobject, and if not, produce a
    /// relevant diagnostic and set the designator as invalid.
    bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK);

    /// Get the type of the designated object.
    QualType getType(ASTContext &Ctx) const {
      assert(!Invalid && "invalid designator has no subobject type");
      return MostDerivedPathLength == Entries.size()
                 ? MostDerivedType12.4k
                 : Ctx.getRecordType(getAsBaseClass(Entries.back()))120;
    }

    /// Update this designator to refer to the first element within this array.
    void addArrayUnchecked(const ConstantArrayType *CAT) {
      Entries.push_back(PathEntry::ArrayIndex(0));

      // This is a most-derived object.
      MostDerivedType = CAT->getElementType();
      MostDerivedIsArrayElement = true;
      MostDerivedArraySize = CAT->getSize().getZExtValue();
      MostDerivedPathLength = Entries.size();
    }
    /// Update this designator to refer to the first element within the array of
    /// elements of type T. This is an array of unknown size.
    void addUnsizedArrayUnchecked(QualType ElemTy) {
      Entries.push_back(PathEntry::ArrayIndex(0));

      MostDerivedType = ElemTy;
      MostDerivedIsArrayElement = true;
      // The value in MostDerivedArraySize is undefined in this case. So, set it
      // to an arbitrary value that's likely to loudly break things if it's
      // used.
      MostDerivedArraySize = AssumedSizeForUnsizedArray;
      MostDerivedPathLength = Entries.size();
    }
    /// Update this designator to refer to the given base or member of this
    /// object.
    void addDeclUnchecked(const Decl *D, bool Virtual = false) {
      Entries.push_back(APValue::BaseOrMemberType(D, Virtual));

      // If this isn't a base class, it's a new most-derived object.
      if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
        MostDerivedType = FD->getType();
        MostDerivedIsArrayElement = false;
        MostDerivedArraySize = 0;
        MostDerivedPathLength = Entries.size();
      }
    }
    /// Update this designator to refer to the given complex component.
    void addComplexUnchecked(QualType EltTy, bool Imag) {
      Entries.push_back(PathEntry::ArrayIndex(Imag));

      // This is technically a most-derived object, though in practice this
      // is unlikely to matter.
      MostDerivedType = EltTy;
      MostDerivedIsArrayElement = true;
      MostDerivedArraySize = 2;
      MostDerivedPathLength = Entries.size();
    }
    void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E);
    void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
                                   const APSInt &N);
    /// Add N to the address of this subobject.
    void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) {
      if (Invalid || !N) return0;
      uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue();
      if (isMostDerivedAnUnsizedArray()) {
        diagnoseUnsizedArrayPointerArithmetic(Info, E);
        // Can't verify -- trust that the user is doing the right thing (or if
        // not, trust that the caller will catch the bad behavior).
        // FIXME: Should we reject if this overflows, at least?
        Entries.back() = PathEntry::ArrayIndex(
            Entries.back().getAsArrayIndex() + TruncatedN);
        return;
      }

      // [expr.add]p4: For the purposes of these operators, a pointer to a
      // nonarray object behaves the same as a pointer to the first element of
      // an array of length one with the type of the object as its element type.
      bool IsArray = MostDerivedPathLength == Entries.size() &&
                     MostDerivedIsArrayElement168k;
      uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()168k
                                    : (uint64_t)IsOnePastTheEnd357;
      uint64_t ArraySize =
          IsArray ? getMostDerivedArraySize()168k : (uint64_t)1357;

      if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex168k) {
        // Calculate the actual index in a wide enough type, so we can include
        // it in the note.
        N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65));
        (llvm::APInt&)N += ArrayIndex;
        assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index");
        diagnosePointerArithmetic(Info, E, N);
        setInvalid();
        return;
      }

      ArrayIndex += TruncatedN;
      assert(ArrayIndex <= ArraySize &&
             "bounds check succeeded for out-of-bounds index");

      if (IsArray)
        Entries.back() = PathEntry::ArrayIndex(ArrayIndex);
      else
        IsOnePastTheEnd = (ArrayIndex != 0);
    }
  };

  /// A scope at the end of which an object can need to be destroyed.
  enum class ScopeKind {
    Block,
    FullExpression,
    Call
  };

  /// A reference to a particular call and its arguments.
  struct CallRef {
    CallRef() : OrigCallee(), CallIndex(0), Version() {}
    CallRef(const FunctionDecl *Callee, unsigned CallIndex, unsigned Version)
        : OrigCallee(Callee), CallIndex(CallIndex), Version(Version) {}

    explicit operator bool() const { return OrigCallee; }

    /// Get the parameter that the caller initialized, corresponding to the
    /// given parameter in the callee.
    const ParmVarDecl *getOrigParam(const ParmVarDecl *PVD) const {
      return OrigCallee ? OrigCallee->getParamDecl(PVD->getFunctionScopeIndex())
                        : PVD0;
    }

    /// The callee at the point where the arguments were evaluated. This might
    /// be different from the actual callee (a different redeclaration, or a
    /// virtual override), but this function's parameters are the ones that
    /// appear in the parameter map.
    const FunctionDecl *OrigCallee;
    /// The call index of the frame that holds the argument values.
    unsigned CallIndex;
    /// The version of the parameters corresponding to this call.
    unsigned Version;
  };

  /// A stack frame in the constexpr call stack.
  class CallStackFrame : public interp::Frame {
  public:
    EvalInfo &Info;

    /// Parent - The caller of this stack frame.
    CallStackFrame *Caller;

    /// Callee - The function which was called.
    const FunctionDecl *Callee;

    /// This - The binding for the this pointer in this call, if any.
    const LValue *This;

    /// Information on how to find the arguments to this call. Our arguments
    /// are stored in our parent's CallStackFrame, using the ParmVarDecl* as a
    /// key and this value as the version.
    CallRef Arguments;

    /// Source location information about the default argument or default
    /// initializer expression we're evaluating, if any.
    CurrentSourceLocExprScope CurSourceLocExprScope;

    // Note that we intentionally use std::map here so that references to
    // values are stable.
    typedef std::pair<const void *, unsigned> MapKeyTy;
    typedef std::map<MapKeyTy, APValue> MapTy;
    /// Temporaries - Temporary lvalues materialized within this stack frame.
    MapTy Temporaries;

    /// CallLoc - The location of the call expression for this call.
    SourceLocation CallLoc;

    /// Index - The call index of this call.
    unsigned Index;

    /// The stack of integers for tracking version numbers for temporaries.
    SmallVector<unsigned, 2> TempVersionStack = {1};
    unsigned CurTempVersion = TempVersionStack.back();

    unsigned getTempVersion() const { return TempVersionStack.back(); }

    void pushTempVersion() {
      TempVersionStack.push_back(++CurTempVersion);
    }

    void popTempVersion() {
      TempVersionStack.pop_back();
    }

    CallRef createCall(const FunctionDecl *Callee) {
      return {Callee, Index, ++CurTempVersion};
    }

    // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact
    // on the overall stack usage of deeply-recursing constexpr evaluations.
    // (We should cache this map rather than recomputing it repeatedly.)
    // But let's try this and see how it goes; we can look into caching the map
    // as a later change.

    /// LambdaCaptureFields - Mapping from captured variables/this to
    /// corresponding data members in the closure class.
    llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields;
    FieldDecl *LambdaThisCaptureField;

    CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
                   const FunctionDecl *Callee, const LValue *This,
                   CallRef Arguments);
    ~CallStackFrame();

    // Return the temporary for Key whose version number is Version.
    APValue *getTemporary(const void *Key, unsigned Version) {
      MapKeyTy KV(Key, Version);
      auto LB = Temporaries.lower_bound(KV);
      if (LB != Temporaries.end() && LB->first == KV328k)
        return &LB->second;
      // Pair (Key,Version) wasn't found in the map. Check that no elements
      // in the map have 'Key' as their key.
      assert((LB == Temporaries.end() || LB->first.first != Key) &&
             (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) &&
             "Element with key 'Key' found in map");
      return nullptr;
    }

    // Return the current temporary for Key in the map.
    APValue *getCurrentTemporary(const void *Key) {
      auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
      if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key2.76k)
        return &std::prev(UB)->second;
      return nullptr;
    }

    // Return the version number of the current temporary for Key.
    unsigned getCurrentTemporaryVersion(const void *Key) const {
      auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
      if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
        return std::prev(UB)->first.second;
      return 0;
    }

    /// Allocate storage for an object of type T in this stack frame.
    /// Populates LV with a handle to the created object. Key identifies
    /// the temporary within the stack frame, and must not be reused without
    /// bumping the temporary version number.
    template<typename KeyT>
    APValue &createTemporary(const KeyT *Key, QualType T,
                             ScopeKind Scope, LValue &LV);

    /// Allocate storage for a parameter of a function call made in this frame.
    APValue &createParam(CallRef Args, const ParmVarDecl *PVD, LValue &LV);

    void describe(llvm::raw_ostream &OS) override;

    Frame *getCaller() const override { return Caller; }
    SourceLocation getCallLocation() const override { return CallLoc; }
    const FunctionDecl *getCallee() const override { return Callee; }

    bool isStdFunction() const {
      for (const DeclContext *DC = Callee; DC; DC = DC->getParent()59)
        if (DC->isStdNamespace())
          return true;
      return false;
    }

  private:
    APValue &createLocal(APValue::LValueBase Base, const void *Key, QualType T,
                         ScopeKind Scope);
  };

  /// Temporarily override 'this'.
  class ThisOverrideRAII {
  public:
    ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
        : Frame(Frame), OldThis(Frame.This) {
      if (Enable)
        Frame.This = NewThis;
    }
    ~ThisOverrideRAII() {
      Frame.This = OldThis;
    }
  private:
    CallStackFrame &Frame;
    const LValue *OldThis;
  };
}

static bool HandleDestruction(EvalInfo &Info, const Expr *E,
                              const LValue &This, QualType ThisType);
static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
                              APValue::LValueBase LVBase, APValue &Value,
                              QualType T);

namespace {
  /// A cleanup, and a flag indicating whether it is lifetime-extended.
  class Cleanup {
    llvm::PointerIntPair<APValue*, 2, ScopeKind> Value;
    APValue::LValueBase Base;
    QualType T;

  public:
    Cleanup(APValue *Val, APValue::LValueBase Base, QualType T,
            ScopeKind Scope)
        : Value(Val, Scope), Base(Base), T(T) {}

    /// Determine whether this cleanup should be performed at the end of the
    /// given kind of scope.
    bool isDestroyedAtEndOf(ScopeKind K) const {
      return (int)Value.getInt() >= (int)K;
    }
    bool endLifetime(EvalInfo &Info, bool RunDestructors) {
      if (RunDestructors) {
        SourceLocation Loc;
        if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
          Loc = VD->getLocation();
        else if (const Expr *E = Base.dyn_cast<const Expr*>())
          Loc = E->getExprLoc();
        return HandleDestruction(Info, Loc, Base, *Value.getPointer(), T);
      }
      *Value.getPointer() = APValue();
      return true;
    }

    bool hasSideEffect() {
      return T.isDestructedType();
    }
  };

  /// A reference to an object whose construction we are currently evaluating.
  struct ObjectUnderConstruction {
    APValue::LValueBase Base;
    ArrayRef<APValue::LValuePathEntry> Path;
    friend bool operator==(const ObjectUnderConstruction &LHS,
                           const ObjectUnderConstruction &RHS) {
      return LHS.Base == RHS.Base && LHS.Path == RHS.Path1.26M;
    }
    friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) {
      return llvm::hash_combine(Obj.Base, Obj.Path);
    }
  };
  enum class ConstructionPhase {
    None,
    Bases,
    AfterBases,
    AfterFields,
    Destroying,
    DestroyingBases
  };
}

namespace llvm {
template<> struct DenseMapInfo<ObjectUnderConstruction> {
  using Base = DenseMapInfo<APValue::LValueBase>;
  static ObjectUnderConstruction getEmptyKey() {
    return {Base::getEmptyKey(), {}}; }
  static ObjectUnderConstruction getTombstoneKey() {
    return {Base::getTombstoneKey(), {}};
  }
  static unsigned getHashValue(const ObjectUnderConstruction &Object) {
    return hash_value(Object);
  }
  static bool isEqual(const ObjectUnderConstruction &LHS,
                      const ObjectUnderConstruction &RHS) {
    return LHS == RHS;
  }
};
}

namespace {
  /// A dynamically-allocated heap object.
  struct DynAlloc {
    /// The value of this heap-allocated object.
    APValue Value;
    /// The allocating expression; used for diagnostics. Either a CXXNewExpr
    /// or a CallExpr (the latter is for direct calls to operator new inside
    /// std::allocator<T>::allocate).
    const Expr *AllocExpr = nullptr;

    enum Kind {
      New,
      ArrayNew,
      StdAllocator
    };

    /// Get the kind of the allocation. This must match between allocation
    /// and deallocation.
    Kind getKind() const {
      if (auto *NE = dyn_cast<CXXNewExpr>(AllocExpr))
        return NE->isArray() ? ArrayNew355 : New124;
      assert(isa<CallExpr>(AllocExpr));
      return StdAllocator;
    }
  };

  struct DynAllocOrder {
    bool operator()(DynamicAllocLValue L, DynamicAllocLValue R) const {
      return L.getIndex() < R.getIndex();
    }
  };

  /// EvalInfo - This is a private struct used by the evaluator to capture
  /// information about a subexpression as it is folded.  It retains information
  /// about the AST context, but also maintains information about the folded
  /// expression.
  ///
  /// If an expression could be evaluated, it is still possible it is not a C
  /// "integer constant expression" or constant expression.  If not, this struct
  /// captures information about how and why not.
  ///
  /// One bit of information passed *into* the request for constant folding
  /// indicates whether the subexpression is "evaluated" or not according to C
  /// rules.  For example, the RHS of (0 && foo()) is not evaluated.  We can
  /// evaluate the expression regardless of what the RHS is, but C only allows
  /// certain things in certain situations.
  class EvalInfo : public interp::State {
  public:
    ASTContext &Ctx;

    /// EvalStatus - Contains information about the evaluation.
    Expr::EvalStatus &EvalStatus;

    /// CurrentCall - The top of the constexpr call stack.
    CallStackFrame *CurrentCall;

    /// CallStackDepth - The number of calls in the call stack right now.
    unsigned CallStackDepth;

    /// NextCallIndex - The next call index to assign.
    unsigned NextCallIndex;

    /// StepsLeft - The remaining number of evaluation steps we're permitted
    /// to perform. This is essentially a limit for the number of statements
    /// we will evaluate.
    unsigned StepsLeft;

    /// Enable the experimental new constant interpreter. If an expression is
    /// not supported by the interpreter, an error is triggered.
    bool EnableNewConstInterp;

    /// BottomFrame - The frame in which evaluation started. This must be
    /// initialized after CurrentCall and CallStackDepth.
    CallStackFrame BottomFrame;

    /// A stack of values whose lifetimes end at the end of some surrounding
    /// evaluation frame.
    llvm::SmallVector<Cleanup, 16> CleanupStack;

    /// EvaluatingDecl - This is the declaration whose initializer is being
    /// evaluated, if any.
    APValue::LValueBase EvaluatingDecl;

    enum class EvaluatingDeclKind {
      None,
      /// We're evaluating the construction of EvaluatingDecl.
      Ctor,
      /// We're evaluating the destruction of EvaluatingDecl.
      Dtor,
    };
    EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None;

    /// EvaluatingDeclValue - This is the value being constructed for the
    /// declaration whose initializer is being evaluated, if any.
    APValue *EvaluatingDeclValue;

    /// Set of objects that are currently being constructed.
    llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase>
        ObjectsUnderConstruction;

    /// Current heap allocations, along with the location where each was
    /// allocated. We use std::map here because we need stable addresses
    /// for the stored APValues.
    std::map<DynamicAllocLValue, DynAlloc, DynAllocOrder> HeapAllocs;

    /// The number of heap allocations performed so far in this evaluation.
    unsigned NumHeapAllocs = 0;

    struct EvaluatingConstructorRAII {
      EvalInfo &EI;
      ObjectUnderConstruction Object;
      bool DidInsert;
      EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object,
                                bool HasBases)
          : EI(EI), Object(Object) {
        DidInsert =
            EI.ObjectsUnderConstruction
                .insert({Object, HasBases ? ConstructionPhase::Bases1.34k
                                          : ConstructionPhase::AfterBases23.1k})
                .second;
      }
      void finishedConstructingBases() {
        EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases;
      }
      void finishedConstructingFields() {
        EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterFields;
      }
      ~EvaluatingConstructorRAII() {
        if (DidInsert) EI.ObjectsUnderConstruction.erase(Object)24.3k;
      }
    };

    struct EvaluatingDestructorRAII {
      EvalInfo &EI;
      ObjectUnderConstruction Object;
      bool DidInsert;
      EvaluatingDestructorRAII(EvalInfo &EI, ObjectUnderConstruction Object)
          : EI(EI), Object(Object) {
        DidInsert = EI.ObjectsUnderConstruction
                        .insert({Object, ConstructionPhase::Destroying})
                        .second;
      }
      void startedDestroyingBases() {
        EI.ObjectsUnderConstruction[Object] =
            ConstructionPhase::DestroyingBases;
      }
      ~EvaluatingDestructorRAII() {
        if (DidInsert)
          EI.ObjectsUnderConstruction.erase(Object);
      }
    };

    ConstructionPhase
    isEvaluatingCtorDtor(APValue::LValueBase Base,
                         ArrayRef<APValue::LValuePathEntry> Path) {
      return ObjectsUnderConstruction.lookup({Base, Path});
    }

    /// If we're currently speculatively evaluating, the outermost call stack
    /// depth at which we can mutate state, otherwise 0.
    unsigned SpeculativeEvaluationDepth = 0;

    /// The current array initialization index, if we're performing array
    /// initialization.
    uint64_t ArrayInitIndex = -1;

    /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
    /// notes attached to it will also be stored, otherwise they will not be.
    bool HasActiveDiagnostic;

    /// Have we emitted a diagnostic explaining why we couldn't constant
    /// fold (not just why it's not strictly a constant expression)?
    bool HasFoldFailureDiagnostic;

    /// Whether or not we're in a context where the front end requires a
    /// constant value.
    bool InConstantContext;

    /// Whether we're checking that an expression is a potential constant
    /// expression. If so, do not fail on constructs that could become constant
    /// later on (such as a use of an undefined global).
    bool CheckingPotentialConstantExpression = false;

    /// Whether we're checking for an expression that has undefined behavior.
    /// If so, we will produce warnings if we encounter an operation that is
    /// always undefined.
    ///
    /// Note that we still need to evaluate the expression normally when this
    /// is set; this is used when evaluating ICEs in C.
    bool CheckingForUndefinedBehavior = false;

    enum EvaluationMode {
      /// Evaluate as a constant expression. Stop if we find that the expression
      /// is not a constant expression.
      EM_ConstantExpression,

      /// Evaluate as a constant expression. Stop if we find that the expression
      /// is not a constant expression. Some expressions can be retried in the
      /// optimizer if we don't constant fold them here, but in an unevaluated
      /// context we try to fold them immediately since the optimizer never
      /// gets a chance to look at it.
      EM_ConstantExpressionUnevaluated,

      /// Fold the expression to a constant. Stop if we hit a side-effect that
      /// we can't model.
      EM_ConstantFold,

      /// Evaluate in any way we know how. Don't worry about side-effects that
      /// can't be modeled.
      EM_IgnoreSideEffects,
    } EvalMode;

    /// Are we checking whether the expression is a potential constant
    /// expression?
    bool checkingPotentialConstantExpression() const override  {
      return CheckingPotentialConstantExpression;
    }

    /// Are we checking an expression for overflow?
    // FIXME: We should check for any kind of undefined or suspicious behavior
    // in such constructs, not just overflow.
    bool checkingForUndefinedBehavior() const override {
      return CheckingForUndefinedBehavior;
    }

    EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
        : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
          CallStackDepth(0), NextCallIndex(1),
          StepsLeft(C.getLangOpts().ConstexprStepLimit),
          EnableNewConstInterp(C.getLangOpts().EnableNewConstInterp),
          BottomFrame(*this, SourceLocation(), nullptr, nullptr, CallRef()),
          EvaluatingDecl((const ValueDecl *)nullptr),
          EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
          HasFoldFailureDiagnostic(false), InConstantContext(false),
          EvalMode(Mode) {}

    ~EvalInfo() {
      discardCleanups();
    }

    ASTContext &getCtx() const override { return Ctx; }

    void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value,
                           EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) {
      EvaluatingDecl = Base;
      IsEvaluatingDecl = EDK;
      EvaluatingDeclValue = &Value;
    }

    bool CheckCallLimit(SourceLocation Loc) {
      // Don't perform any constexpr calls (other than the call we're checking)
      // when checking a potential constant expression.
      if (checkingPotentialConstantExpression() && CallStackDepth > 149.3k)
        return false;
      if (NextCallIndex == 0) {
        // NextCallIndex has wrapped around.
        FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
        return false;
      }
      if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
        return true;
      FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
        << getLangOpts().ConstexprCallDepth;
      return false;
    }

    std::pair<CallStackFrame *, unsigned>
    getCallFrameAndDepth(unsigned CallIndex) {
      assert(CallIndex && "no call index in getCallFrameAndDepth");
      // We will eventually hit BottomFrame, which has Index 1, so Frame can't
      // be null in this loop.
      unsigned Depth = CallStackDepth;
      CallStackFrame *Frame = CurrentCall;
      while (Frame->Index > CallIndex) {
        Frame = Frame->Caller;
        --Depth;
      }
      if (Frame->Index == CallIndex)
        return {Frame, Depth};
      return {nullptr, 0};
    }

    bool nextStep(const Stmt *S) {
      if (!StepsLeft) {
        FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded);
        return false;
      }
      --StepsLeft;
      return true;
    }

    APValue *createHeapAlloc(const Expr *E, QualType T, LValue &LV);

    Optional<DynAlloc*> lookupDynamicAlloc(DynamicAllocLValue DA) {
      Optional<DynAlloc*> Result;
      auto It = HeapAllocs.find(DA);
      if (It != HeapAllocs.end())
        Result = &It->second;
      return Result;
    }

    /// Get the allocated storage for the given parameter of the given call.
    APValue *getParamSlot(CallRef Call, const ParmVarDecl *PVD) {
      CallStackFrame *Frame = getCallFrameAndDepth(Call.CallIndex).first;
      return Frame ? Frame->getTemporary(Call.getOrigParam(PVD), Call.Version)
                   : nullptr0;
    }

    /// Information about a stack frame for std::allocator<T>::[de]allocate.
    struct StdAllocatorCaller {
      unsigned FrameIndex;
      QualType ElemType;
      explicit operator bool() const { return FrameIndex != 0; };
    };

    StdAllocatorCaller getStdAllocatorCaller(StringRef FnName) const {
      for (const CallStackFrame *Call = CurrentCall; Call != &BottomFrame;
           Call = Call->Caller33) {
        const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Call->Callee);
        if (!MD)
          continue;
        const IdentifierInfo *FnII = MD->getIdentifier();
        if (!FnII || !FnII->isStr(FnName)146)
          continue;

        const auto *CTSD =
            dyn_cast<ClassTemplateSpecializationDecl>(MD->getParent());
        if (!CTSD)
          continue;

        const IdentifierInfo *ClassII = CTSD->getIdentifier();
        const TemplateArgumentList &TAL = CTSD->getTemplateArgs();
        if (CTSD->isInStdNamespace() && ClassII &&
            ClassII->isStr("allocator") && TAL.size() >= 1 &&
            TAL[0].getKind() == TemplateArgument::Type)
          return {Call->Index, TAL[0].getAsType()};
      }

      return {};
    }

    void performLifetimeExtension() {
      // Disable the cleanups for lifetime-extended temporaries.
      llvm::erase_if(CleanupStack, [](Cleanup &C) {
        return !C.isDestroyedAtEndOf(ScopeKind::FullExpression);
      });
    }

    /// Throw away any remaining cleanups at the end of evaluation. If any
    /// cleanups would have had a side-effect, note that as an unmodeled
    /// side-effect and return false. Otherwise, return true.
    bool discardCleanups() {
      for (Cleanup &C : CleanupStack) {
        if (C.hasSideEffect() && !noteSideEffect()1.64k) {
          CleanupStack.clear();
          return false;
        }
      }
      CleanupStack.clear();
      return true;
    }

  private:
    interp::Frame *getCurrentFrame() override { return CurrentCall; }
    const interp::Frame *getBottomFrame() const override { return &BottomFrame; }

    bool hasActiveDiagnostic() override { return HasActiveDiagnostic; }
    void setActiveDiagnostic(bool Flag) override { HasActiveDiagnostic = Flag; }

    void setFoldFailureDiagnostic(bool Flag) override {
      HasFoldFailureDiagnostic = Flag;
    }

    Expr::EvalStatus &getEvalStatus() const override { return EvalStatus; }

    // If we have a prior diagnostic, it will be noting that the expression
    // isn't a constant expression. This diagnostic is more important,
    // unless we require this evaluation to produce a constant expression.
    //
    // FIXME: We might want to show both diagnostics to the user in
    // EM_ConstantFold mode.
    bool hasPriorDiagnostic() override {
      if (!EvalStatus.Diag->empty()) {
        switch (EvalMode) {
        case EM_ConstantFold:
        case EM_IgnoreSideEffects:
          if (!HasFoldFailureDiagnostic)
            break;
          // We've already failed to fold something. Keep that diagnostic.
          LLVM_FALLTHROUGH77;77
        case EM_ConstantExpression:
        case EM_ConstantExpressionUnevaluated:
          setActiveDiagnostic(false);
          return true;
        }
      }
      return false;
    }

    unsigned getCallStackDepth() override { return CallStackDepth; }

  public:
    /// Should we continue evaluation after encountering a side-effect that we
    /// couldn't model?
    bool keepEvaluatingAfterSideEffect() {
      switch (EvalMode) {
      case EM_IgnoreSideEffects:
        return true;

      case EM_ConstantExpression:
      case EM_ConstantExpressionUnevaluated:
      case EM_ConstantFold:
        // By default, assume any side effect might be valid in some other
        // evaluation of this expression from a different context.
        return checkingPotentialConstantExpression() ||
               checkingForUndefinedBehavior()1.13k;
      }
      llvm_unreachable("Missed EvalMode case");
    }

    /// Note that we have had a side-effect, and determine whether we should
    /// keep evaluating.
    bool noteSideEffect() {
      EvalStatus.HasSideEffects = true;
      return keepEvaluatingAfterSideEffect();
    }

    /// Should we continue evaluation after encountering undefined behavior?
    bool keepEvaluatingAfterUndefinedBehavior() {
      switch (EvalMode) {
      case EM_IgnoreSideEffects:
      case EM_ConstantFold:
        return true;

      case EM_ConstantExpression:
      case EM_ConstantExpressionUnevaluated:
        return checkingForUndefinedBehavior();
      }
      llvm_unreachable("Missed EvalMode case");
    }

    /// Note that we hit something that was technically undefined behavior, but
    /// that we can evaluate past it (such as signed overflow or floating-point
    /// division by zero.)
    bool noteUndefinedBehavior() override {
      EvalStatus.HasUndefinedBehavior = true;
      return keepEvaluatingAfterUndefinedBehavior();
    }

    /// Should we continue evaluation as much as possible after encountering a
    /// construct which can't be reduced to a value?
    bool keepEvaluatingAfterFailure() const override {
      if (!StepsLeft)
        return false;

      switch (EvalMode) {
      case EM_ConstantExpression:
      case EM_ConstantExpressionUnevaluated:
      case EM_ConstantFold:
      case EM_IgnoreSideEffects:
        return checkingPotentialConstantExpression() ||
               checkingForUndefinedBehavior()4.46M;
      }
      llvm_unreachable("Missed EvalMode case");
    }

    /// Notes that we failed to evaluate an expression that other expressions
    /// directly depend on, and determine if we should keep evaluating. This
    /// should only be called if we actually intend to keep evaluating.
    ///
    /// Call noteSideEffect() instead if we may be able to ignore the value that
    /// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
    ///
    /// (Foo(), 1)      // use noteSideEffect
    /// (Foo() || true) // use noteSideEffect
    /// Foo() + 1       // use noteFailure
    LLVM_NODISCARD bool noteFailure() {
      // Failure when evaluating some expression often means there is some
      // subexpression whose evaluation was skipped. Therefore, (because we
      // don't track whether we skipped an expression when unwinding after an
      // evaluation failure) every evaluation failure that bubbles up from a
      // subexpression implies that a side-effect has potentially happened. We
      // skip setting the HasSideEffects flag to true until we decide to
      // continue evaluating after that point, which happens here.
      bool KeepGoing = keepEvaluatingAfterFailure();
      EvalStatus.HasSideEffects |= KeepGoing;
      return KeepGoing;
    }

    class ArrayInitLoopIndex {
      EvalInfo &Info;
      uint64_t OuterIndex;

    public:
      ArrayInitLoopIndex(EvalInfo &Info)
          : Info(Info), OuterIndex(Info.ArrayInitIndex) {
        Info.ArrayInitIndex = 0;
      }
      ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }

      operator uint64_t&() { return Info.ArrayInitIndex; }
    };
  };

  /// Object used to treat all foldable expressions as constant expressions.
  struct FoldConstant {
    EvalInfo &Info;
    bool Enabled;
    bool HadNoPriorDiags;
    EvalInfo::EvaluationMode OldMode;

    explicit FoldConstant(EvalInfo &Info, bool Enabled)
      : Info(Info),
        Enabled(Enabled),
        HadNoPriorDiags(Info.EvalStatus.Diag &&
                        Info.EvalStatus.Diag->empty() &&
                        !Info.EvalStatus.HasSideEffects),
        OldMode(Info.EvalMode) {
      if (Enabled)
        Info.EvalMode = EvalInfo::EM_ConstantFold;
    }
    void keepDiagnostics() { Enabled = false; }
    ~FoldConstant() {
      if (Enabled && HadNoPriorDiags1.81k && !Info.EvalStatus.Diag->empty()67 &&
          !Info.EvalStatus.HasSideEffects67)
        Info.EvalStatus.Diag->clear();
      Info.EvalMode = OldMode;
    }
  };

  /// RAII object used to set the current evaluation mode to ignore
  /// side-effects.
  struct IgnoreSideEffectsRAII {
    EvalInfo &Info;
    EvalInfo::EvaluationMode OldMode;
    explicit IgnoreSideEffectsRAII(EvalInfo &Info)
        : Info(Info), OldMode(Info.EvalMode) {
      Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
    }

    ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; }
  };

  /// RAII object used to optionally suppress diagnostics and side-effects from
  /// a speculative evaluation.
  class SpeculativeEvaluationRAII {
    EvalInfo *Info = nullptr;
    Expr::EvalStatus OldStatus;
    unsigned OldSpeculativeEvaluationDepth;

    void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
      Info = Other.Info;
      OldStatus = Other.OldStatus;
      OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth;
      Other.Info = nullptr;
    }

    void maybeRestoreState() {
      if (!Info)
        return;

      Info->EvalStatus = OldStatus;
      Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth;
    }

  public:
    SpeculativeEvaluationRAII() = default;

    SpeculativeEvaluationRAII(
        EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
        : Info(&Info), OldStatus(Info.EvalStatus),
          OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) {
      Info.EvalStatus.Diag = NewDiag;
      Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1;
    }

    SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
    SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
      moveFromAndCancel(std::move(Other));
    }

    SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
      maybeRestoreState();
      moveFromAndCancel(std::move(Other));
      return *this;
    }

    ~SpeculativeEvaluationRAII() { maybeRestoreState(); }
  };

  /// RAII object wrapping a full-expression or block scope, and handling
  /// the ending of the lifetime of temporaries created within it.
  template<ScopeKind Kind>
  class ScopeRAII {
    EvalInfo &Info;
    unsigned OldStackSize;
  public:
    ScopeRAII(EvalInfo &Info)
        : Info(Info), OldStackSize(Info.CleanupStack.size()) {
      // Push a new temporary version. This is needed to distinguish between
      // temporaries created in different iterations of a loop.
      Info.CurrentCall->pushTempVersion();
    }
    bool destroy(bool RunDestructors = true) {
      bool OK = cleanup(Info, RunDestructors, OldStackSize);
      OldStackSize = -1U;
      return OK;
    }
    ~ScopeRAII() {
      if (OldStackSize != -1U)
        destroy(false);
      // Body moved to a static method to encourage the compiler to inline away
      // instances of this class.
      Info.CurrentCall->popTempVersion();
    }
  private:
    static bool cleanup(EvalInfo &Info, bool RunDestructors,
                        unsigned OldStackSize) {
      assert(OldStackSize <= Info.CleanupStack.size() &&
             "running cleanups out of order?");

      // Run all cleanups for a block scope, and non-lifetime-extended cleanups
      // for a full-expression scope.
      bool Success = true;
      for (unsigned I = Info.CleanupStack.size(); I > OldStackSize; --I512k) {
        if (Info.CleanupStack[I - 1].isDestroyedAtEndOf(Kind)) {
          if (!Info.CleanupStack[I - 1].endLifetime(Info, RunDestructors)) {
            Success = false;
            break;
          }
        }
      }

      // Compact any retained cleanups.
      auto NewEnd = Info.CleanupStack.begin() + OldStackSize;
      if (Kind != ScopeKind::Block)
        NewEnd =
            std::remove_if(NewEnd, Info.CleanupStack.end(), [](Cleanup &C) {
              return C.isDestroyedAtEndOf(Kind);
            });
      Info.CleanupStack.erase(NewEnd, Info.CleanupStack.end());
      return Success;
    }
  };
  typedef ScopeRAII<ScopeKind::Block> BlockScopeRAII;
  typedef ScopeRAII<ScopeKind::FullExpression> FullExpressionRAII;
  typedef ScopeRAII<ScopeKind::Call> CallScopeRAII;
}

bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
                                         CheckSubobjectKind CSK) {
  if (Invalid)
    return false;
  if (isOnePastTheEnd()) {
    Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
      << CSK;
    setInvalid();
    return false;
  }
  // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
  // must actually be at least one array element; even a VLA cannot have a
  // bound of zero. And if our index is nonzero, we already had a CCEDiag.
  return true;
}

void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
                                                                const Expr *E) {
  Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
  // Do not set the designator as invalid: we can represent this situation,
  // and correct handling of __builtin_object_size requires us to do so.
}

void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
                                                    const Expr *E,
                                                    const APSInt &N) {
  // If we're complaining, we must be able to statically determine the size of
  // the most derived array.
  if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement423)
    Info.CCEDiag(E, diag::note_constexpr_array_index)
      << N << /*array*/ 0
      << static_cast<unsigned>(getMostDerivedArraySize());
  else
    Info.CCEDiag(E, diag::note_constexpr_array_index)
      << N << /*non-array*/ 1;
  setInvalid();
}

CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
                               const FunctionDecl *Callee, const LValue *This,
                               CallRef Call)
    : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
      Arguments(Call), CallLoc(CallLoc), Index(Info.NextCallIndex++) {
  Info.CurrentCall = this;
  ++Info.CallStackDepth;
}

CallStackFrame::~CallStackFrame() {
  assert(Info.CurrentCall == this && "calls retired out of order");
  --Info.CallStackDepth;
  Info.CurrentCall = Caller;
}

static bool isRead(AccessKinds AK) {
  return AK == AK_Read || AK == AK_ReadObjectRepresentation308k;
}

static bool isModification(AccessKinds AK) {
  switch (AK) {
  case AK_Read:
  case AK_ReadObjectRepresentation:
  case AK_MemberCall:
  case AK_DynamicCast:
  case AK_TypeId:
    return false;
  case AK_Assign:
  case AK_Increment:
  case AK_Decrement:
  case AK_Construct:
  case AK_Destroy:
    return true;
  }
  llvm_unreachable("unknown access kind");
}

static bool isAnyAccess(AccessKinds AK) {
  return isRead(AK) || isModification(AK)305k;
}

/// Is this an access per the C++ definition?
static bool isFormalAccess(AccessKinds AK) {
  return isAnyAccess(AK) && AK != AK_Construct6.72M && AK != AK_Destroy6.72M;
}

/// Is this kind of axcess valid on an indeterminate object value?
static bool isValidIndeterminateAccess(AccessKinds AK) {
  switch (AK) {
  case AK_Read:
  case AK_Increment:
  case AK_Decrement:
    // These need the object's value.
    return false;

  case AK_ReadObjectRepresentation:
  case AK_Assign:
  case AK_Construct:
  case AK_Destroy:
    // Construction and destruction don't need the value.
    return true;

  case AK_MemberCall:
  case AK_DynamicCast:
  case AK_TypeId:
    // These aren't really meaningful on scalars.
    return true;
  }
  llvm_unreachable("unknown access kind");
}

namespace {
  struct ComplexValue {
  private:
    bool IsInt;

  public:
    APSInt IntReal, IntImag;
    APFloat FloatReal, FloatImag;

    ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}

    void makeComplexFloat() { IsInt = false; }
    bool isComplexFloat() const { return !IsInt; }
    APFloat &getComplexFloatReal() { return FloatReal; }
    APFloat &getComplexFloatImag() { return FloatImag; }

    void makeComplexInt() { IsInt = true; }
    bool isComplexInt() const { return IsInt; }
    APSInt &getComplexIntReal() { return IntReal; }
    APSInt &getComplexIntImag() { return IntImag; }

    void moveInto(APValue &v) const {
      if (isComplexFloat())
        v = APValue(FloatReal, FloatImag);
      else
        v = APValue(IntReal, IntImag);
    }
    void setFrom(const APValue &v) {
      assert(v.isComplexFloat() || v.isComplexInt());
      if (v.isComplexFloat()) {
        makeComplexFloat();
        FloatReal = v.getComplexFloatReal();
        FloatImag = v.getComplexFloatImag();
      } else {
        makeComplexInt();
        IntReal = v.getComplexIntReal();
        IntImag = v.getComplexIntImag();
      }
    }
  };

  struct LValue {
    APValue::LValueBase Base;
    CharUnits Offset;
    SubobjectDesignator Designator;
    bool IsNullPtr : 1;
    bool InvalidBase : 1;

    const APValue::LValueBase getLValueBase() const { return Base; }
    CharUnits &getLValueOffset() { return Offset; }
    const CharUnits &getLValueOffset() const { return Offset; }
    SubobjectDesignator &getLValueDesignator() { return Designator; }
    const SubobjectDesignator &getLValueDesignator() const { return Designator;}
    bool isNullPointer() const { return IsNullPtr;}

    unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
    unsigned getLValueVersion() const { return Base.getVersion(); }

    void moveInto(APValue &V) const {
      if (Designator.Invalid)
        V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
      else {
        assert(!InvalidBase && "APValues can't handle invalid LValue bases");
        V = APValue(Base, Offset, Designator.Entries,
                    Designator.IsOnePastTheEnd, IsNullPtr);
      }
    }
    void setFrom(ASTContext &Ctx, const APValue &V) {
      assert(V.isLValue() && "Setting LValue from a non-LValue?");
      Base = V.getLValueBase();
      Offset = V.getLValueOffset();
      InvalidBase = false;
      Designator = SubobjectDesignator(Ctx, V);
      IsNullPtr = V.isNullPointer();
    }

    void set(APValue::LValueBase B, bool BInvalid = false) {
#ifndef NDEBUG
      // We only allow a few types of invalid bases. Enforce that here.
      if (BInvalid) {
        const auto *E = B.get<const Expr *>();
        assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
               "Unexpected type of invalid base");
      }
#endif

      Base = B;
      Offset = CharUnits::fromQuantity(0);
      InvalidBase = BInvalid;
      Designator = SubobjectDesignator(getType(B));
      IsNullPtr = false;
    }

    void setNull(ASTContext &Ctx, QualType PointerTy) {
      Base = (const ValueDecl *)nullptr;
      Offset =
          CharUnits::fromQuantity(Ctx.getTargetNullPointerValue(PointerTy));
      InvalidBase = false;
      Designator = SubobjectDesignator(PointerTy->getPointeeType());
      IsNullPtr = true;
    }

    void setInvalid(APValue::LValueBase B, unsigned I = 0) {
      set(B, true);
    }

    std::string toString(ASTContext &Ctx, QualType T) const {
      APValue Printable;
      moveInto(Printable);
      return Printable.getAsString(Ctx, T);
    }

  private:
    // Check that this LValue is not based on a null pointer. If it is, produce
    // a diagnostic and mark the designator as invalid.
    template <typename GenDiagType>
    bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) {
      if (Designator.Invalid)
        return false;
      if (IsNullPtr) {
        GenDiag();
        Designator.setInvalid();
        return false;
      }
      return true;
    }

  public:
    bool checkNullPointer(EvalInfo &Info, const Expr *E,
                          CheckSubobjectKind CSK) {
      return checkNullPointerDiagnosingWith([&Info, E, CSK] {
        Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK;
      });
    }

    bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E,
                                       AccessKinds AK) {
      return checkNullPointerDiagnosingWith([&Info, E, AK] {
        Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
      });
    }

    // Check this LValue refers to an object. If not, set the designator to be
    // invalid and emit a diagnostic.
    bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
      return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)175k) &&
             Designator.checkSubobject(Info, E, CSK)262k;
    }

    void addDecl(EvalInfo &Info, const Expr *E,
                 const Decl *D, bool Virtual = false) {
      if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field163k : CSK_Base12.2k))
        Designator.addDeclUnchecked(D, Virtual);
    }
    void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
      if (!Designator.Entries.empty()) {
        Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
        Designator.setInvalid();
        return;
      }
      if (checkSubobject(Info, E, CSK_ArrayToPointer)) {
        assert(getType(Base)->isPointerType() || getType(Base)->isArrayType());
        Designator.FirstEntryIsAnUnsizedArray = true;
        Designator.addUnsizedArrayUnchecked(ElemTy);
      }
    }
    void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
      if (checkSubobject(Info, E, CSK_ArrayToPointer))
        Designator.addArrayUnchecked(CAT);
    }
    void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
      if (checkSubobject(Info, E, Imag ? CSK_Imag111 : CSK_Real122))
        Designator.addComplexUnchecked(EltTy, Imag);
    }
    void clearIsNullPointer() {
      IsNullPtr = false;
    }
    void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
                              const APSInt &Index, CharUnits ElementSize) {
      // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
      // but we're not required to diagnose it and it's valid in C++.)
      if (!Index)
        return;

      // Compute the new offset in the appropriate width, wrapping at 64 bits.
      // FIXME: When compiling for a 32-bit target, we should use 32-bit
      // offsets.
      uint64_t Offset64 = Offset.getQuantity();
      uint64_t ElemSize64 = ElementSize.getQuantity();
      uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
      Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);

      if (checkNullPointer(Info, E, CSK_ArrayIndex))
        Designator.adjustIndex(Info, E, Index);
      clearIsNullPointer();
    }
    void adjustOffset(CharUnits N) {
      Offset += N;
      if (N.getQuantity())
        clearIsNullPointer();
    }
  };

  struct MemberPtr {
    MemberPtr() {}
    explicit MemberPtr(const ValueDecl *Decl)
        : DeclAndIsDerivedMember(Decl, false) {}

    /// The member or (direct or indirect) field referred to by this member
    /// pointer, or 0 if this is a null member pointer.
    const ValueDecl *getDecl() const {
      return DeclAndIsDerivedMember.getPointer();
    }
    /// Is this actually a member of some type derived from the relevant class?
    bool isDerivedMember() const {
      return DeclAndIsDerivedMember.getInt();
    }
    /// Get the class which the declaration actually lives in.
    const CXXRecordDecl *getContainingRecord() const {
      return cast<CXXRecordDecl>(
          DeclAndIsDerivedMember.getPointer()->getDeclContext());
    }

    void moveInto(APValue &V) const {
      V = APValue(getDecl(), isDerivedMember(), Path);
    }
    void setFrom(const APValue &V) {
      assert(V.isMemberPointer());
      DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
      DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
      Path.clear();
      ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath();
      Path.insert(Path.end(), P.begin(), P.end());
    }

    /// DeclAndIsDerivedMember - The member declaration, and a flag indicating
    /// whether the member is a member of some class derived from the class type
    /// of the member pointer.
    llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
    /// Path - The path of base/derived classes from the member declaration's
    /// class (exclusive) to the class type of the member pointer (inclusive).
    SmallVector<const CXXRecordDecl*, 4> Path;

    /// Perform a cast towards the class of the Decl (either up or down the
    /// hierarchy).
    bool castBack(const CXXRecordDecl *Class) {
      assert(!Path.empty());
      const CXXRecordDecl *Expected;
      if (Path.size() >= 2)
        Expected = Path[Path.size() - 2];
      else
        Expected = getContainingRecord();
      if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
        // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
        // if B does not contain the original member and is not a base or
        // derived class of the class containing the original member, the result
        // of the cast is undefined.
        // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
        // (D::*). We consider that to be a language defect.
        return false;
      }
      Path.pop_back();
      return true;
    }
    /// Perform a base-to-derived member pointer cast.
    bool castToDerived(const CXXRecordDecl *Derived) {
      if (!getDecl())
        return true;
      if (!isDerivedMember()) {
        Path.push_back(Derived);
        return true;
      }
      if (!castBack(Derived))
        return false;
      if (Path.empty())
        DeclAndIsDerivedMember.setInt(false);
      return true;
    }
    /// Perform a derived-to-base member pointer cast.
    bool castToBase(const CXXRecordDecl *Base) {
      if (!getDecl())
        return true;
      if (Path.empty())
        DeclAndIsDerivedMember.setInt(true);
      if (isDerivedMember()) {
        Path.push_back(Base);
        return true;
      }
      return castBack(Base);
    }
  };

  /// Compare two member pointers, which are assumed to be of the same type.
  static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
    if (!LHS.getDecl() || !RHS.getDecl())
      return !LHS.getDecl() && !RHS.getDecl();
    if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
      return false;
    return LHS.Path == RHS.Path;
  }
}

static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
                            const LValue &This, const Expr *E,
                            bool AllowNonLiteralTypes = false);
static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
                           bool InvalidBaseOK = false);
static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
                            bool InvalidBaseOK = false);
static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
                                  EvalInfo &Info);
static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
                                    EvalInfo &Info);
static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
                           EvalInfo &Info);
static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
                                  EvalInfo &Info);

/// Evaluate an integer or fixed point expression into an APResult.
static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
                                        EvalInfo &Info);

/// Evaluate only a fixed point expression into an APResult.
static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
                               EvalInfo &Info);

//===----------------------------------------------------------------------===//
// Misc utilities
//===----------------------------------------------------------------------===//

/// Negate an APSInt in place, converting it to a signed form if necessary, and
/// preserving its value (by extending by up to one bit as needed).
static void negateAsSigned(APSInt &Int) {
  if (Int.isUnsigned() || Int.isMinSignedValue()266) {
    Int = Int.extend(Int.getBitWidth() + 1);
    Int.setIsSigned(true);
  }
  Int = -Int;
}

template<typename KeyT>
APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T,
                                         ScopeKind Scope, LValue &LV) {
  unsigned Version = getTempVersion();
  APValue::LValueBase Base(Key, Index, Version);
  LV.set(Base);
  return createLocal(Base, Key, T, Scope);
}

/// Allocate storage for a parameter of a function call made in this frame.
APValue &CallStackFrame::createParam(CallRef Args, const ParmVarDecl *PVD,
                                     LValue &LV) {
  assert(Args.CallIndex == Index && "creating parameter in wrong frame");
  APValue::LValueBase Base(PVD, Index, Args.Version);
  LV.set(Base);
  // We always destroy parameters at the end of the call, even if we'd allow
  // them to live to the end of the full-expression at runtime, in order to
  // give portable results and match other compilers.
  return createLocal(Base, PVD, PVD->getType(), ScopeKind::Call);
}

APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key,
                                     QualType T, ScopeKind Scope) {
  assert(Base.getCallIndex() == Index && "lvalue for wrong frame");
  unsigned Version = Base.getVersion();
  APValue &Result = Temporaries[MapKeyTy(Key, Version)];
  assert(Result.isAbsent() && "local created multiple times");

  // If we're creating a local immediately in the operand of a speculative
  // evaluation, don't register a cleanup to be run outside the speculative
  // evaluation context, since we won't actually be able to initialize this
  // object.
  if (Index <= Info.SpeculativeEvaluationDepth) {
    if (T.isDestructedType())
      Info.noteSideEffect();
  } else {
    Info.CleanupStack.push_back(Cleanup(&Result, Base, T, Scope));
  }
  return Result;
}

APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) {
  if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) {
    FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded);
    return nullptr;
  }

  DynamicAllocLValue DA(NumHeapAllocs++);
  LV.set(APValue::LValueBase::getDynamicAlloc(DA, T));
  auto Result = HeapAllocs.emplace(std::piecewise_construct,
                                   std::forward_as_tuple(DA), std::tuple<>());
  assert(Result.second && "reused a heap alloc index?");
  Result.first->second.AllocExpr = E;
  return &Result.first->second.Value;
}

/// Produce a string describing the given constexpr call.
void CallStackFrame::describe(raw_ostream &Out) {
  unsigned ArgIndex = 0;
  bool IsMemberCall = isa<CXXMethodDecl>(Callee) &&
                      !isa<CXXConstructorDecl>(Callee)1.31k &&
                      cast<CXXMethodDecl>(Callee)->isInstance()838;

  if (!IsMemberCall)
    Out << *Callee << '(';

  if (This && IsMemberCall1.31k) {
    APValue Val;
    This->moveInto(Val);
    Val.printPretty(Out, Info.Ctx,
                    This->Designator.MostDerivedType);
    // FIXME: Add parens around Val if needed.
    Out << "->" << *Callee << '(';
    IsMemberCall = false;
  }

  for (FunctionDecl::param_const_iterator I = Callee->param_begin(),
       E = Callee->param_end(); I != E; ++I, ++ArgIndex1.90k) {
    if (ArgIndex > (unsigned)IsMemberCall)
      Out << ", ";

    const ParmVarDecl *Param = *I;
    APValue *V = Info.getParamSlot(Arguments, Param);
    if (V)
      V->printPretty(Out, Info.Ctx, Param->getType());
    else
      Out << "<...>";

    if (ArgIndex == 0 && IsMemberCall1.25k)
      Out << "->" << *Callee << '(';
  }

  Out << ')';
}

/// Evaluate an expression to see if it had side-effects, and discard its
/// result.
/// \return \c true if the caller should keep evaluating.
static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
  assert(!E->isValueDependent());
  APValue Scratch;
  if (!Evaluate(Scratch, Info, E))
    // We don't need the value, but we might have skipped a side effect here.
    return Info.noteSideEffect();
  return true;
}

/// Should this call expression be treated as a constant?
static bool IsConstantCall(const CallExpr *E) {
  unsigned Builtin = E->getBuiltinCallee();
  return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
          Builtin == Builtin::BI__builtin___NSStringMakeConstantString30.0k ||
          Builtin == Builtin::BI__builtin_function_start30.0k);
}

static bool IsGlobalLValue(APValue::LValueBase B) {
  // C++11 [expr.const]p3 An address constant expression is a prvalue core
  // constant expression of pointer type that evaluates to...

  // ... a null pointer value, or a prvalue core constant expression of type
  // std::nullptr_t.
  if (!B) return true23.0k;

  if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
    // ... the address of an object with static storage duration,
    if (const VarDecl *VD = dyn_cast<VarDecl>(D))
      return VD->hasGlobalStorage();
    if (isa<TemplateParamObjectDecl>(D))
      return true;
    // ... the address of a function,
    // ... the address of a GUID [MS extension],
    // ... the address of an unnamed global constant
    return isa<FunctionDecl, MSGuidDecl, UnnamedGlobalConstantDecl>(D);
  }

  if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>()11.3k)
    return true;

  const Expr *E = B.get<const Expr*>();
  switch (E->getStmtClass()) {
  default:
    return false;
  case Expr::CompoundLiteralExprClass: {
    const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
    return CLE->isFileScope() && CLE->isLValue()87;
  }
  case Expr::MaterializeTemporaryExprClass:
    // A materialized temporary might have been lifetime-extended to static
    // storage duration.
    return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
  // A string literal has static storage duration.
  case Expr::StringLiteralClass:
  case Expr::PredefinedExprClass:
  case Expr::ObjCStringLiteralClass:
  case Expr::ObjCEncodeExprClass:
    return true;
  case Expr::ObjCBoxedExprClass:
    return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer();
  case Expr::CallExprClass:
    return IsConstantCall(cast<CallExpr>(E));
  // For GCC compatibility, &&label has static storage duration.
  case Expr::AddrLabelExprClass:
    return true;
  // A Block literal expression may be used as the initialization value for
  // Block variables at global or local static scope.
  case Expr::BlockExprClass:
    return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
  // The APValue generated from a __builtin_source_location will be emitted as a
  // literal.
  case Expr::SourceLocExprClass:
    return true;
  case Expr::ImplicitValueInitExprClass:
    // FIXME:
    // We can never form an lvalue with an implicit value initialization as its
    // base through expression evaluation, so these only appear in one case: the
    // implicit variable declaration we invent when checking whether a constexpr
    // constructor can produce a constant expression. We must assume that such
    // an expression might be a global lvalue.
    return true;
  }
}

static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
  return LVal.Base.dyn_cast<const ValueDecl*>();
}

static bool IsLiteralLValue(const LValue &Value) {
  if (Value.getLValueCallIndex())
    return false;
  const Expr *E = Value.Base.dyn_cast<const Expr*>();
  return E && !isa<MaterializeTemporaryExpr>(E)108;
}

static bool IsWeakLValue(const LValue &Value) {
  const ValueDecl *Decl = GetLValueBaseDecl(Value);
  return Decl && Decl->isWeak()633;
}

static bool isZeroSized(const LValue &Value) {
  const ValueDecl *Decl = GetLValueBaseDecl(Value);
  if (Decl && isa<VarDecl>(Decl)234) {
    QualType Ty = Decl->getType();
    if (Ty->isArrayType())
      return Ty->isIncompleteType() ||
             Decl->getASTContext().getTypeSize(Ty) == 042;
  }
  return false;
}

static bool HasSameBase(const LValue &A, const LValue &B) {
  if (!A.getLValueBase())
    return !B.getLValueBase();
  if (!B.getLValueBase())
    return false;

  if (A.getLValueBase().getOpaqueValue() !=
      B.getLValueBase().getOpaqueValue())
    return false;

  return A.getLValueCallIndex() == B.getLValueCallIndex() &&
         A.getLValueVersion() == B.getLValueVersion();
}

static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
  assert(Base && "no location for a null lvalue");
  const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();

  // For a parameter, find the corresponding call stack frame (if it still
  // exists), and point at the parameter of the function definition we actually
  // invoked.
  if (auto *PVD = dyn_cast_or_null<ParmVarDecl>(VD)) {
    unsigned Idx = PVD->getFunctionScopeIndex();
    for (CallStackFrame *F = Info.CurrentCall; F; F = F->Caller1.04M) {
      if (F->Arguments.CallIndex == Base.getCallIndex() &&
          F->Arguments.Version == Base.getVersion()1.02M && F->Callee1.02M &&
          Idx < F->Callee->getNumParams()15) {
        VD = F->Callee->getParamDecl(Idx);
        break;
      }
    }
  }

  if (VD)
    Info.Note(VD->getLocation(), diag::note_declared_at);
  else if (const Expr *E = Base.dyn_cast<const Expr*>())
    Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here);
  else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
    // FIXME: Produce a note for dangling pointers too.
    if (Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA))
      Info.Note((*Alloc)->AllocExpr->getExprLoc(),
                diag::note_constexpr_dynamic_alloc_here);
  }
  // We have no information to show for a typeid(T) object.
}

enum class CheckEvaluationResultKind {
  ConstantExpression,
  FullyInitialized,
};

/// Materialized temporaries that we've already checked to determine if they're
/// initializsed by a constant expression.
using CheckedTemporaries =
    llvm::SmallPtrSet<const MaterializeTemporaryExpr *, 8>;

static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
                                  EvalInfo &Info, SourceLocation DiagLoc,
                                  QualType Type, const APValue &Value,
                                  ConstantExprKind Kind,
                                  SourceLocation SubobjectLoc,
                                  CheckedTemporaries &CheckedTemps);

/// Check that this reference or pointer core constant expression is a valid
/// value for an address or reference constant expression. Return true if we
/// can fold this expression, whether or not it's a constant expression.
static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
                                          QualType Type, const LValue &LVal,
                                          ConstantExprKind Kind,
                                          CheckedTemporaries &CheckedTemps) {
  bool IsReferenceType = Type->isReferenceType();

  APValue::LValueBase Base = LVal.getLValueBase();
  const SubobjectDesignator &Designator = LVal.getLValueDesignator();

  const Expr *BaseE = Base.dyn_cast<const Expr *>();
  const ValueDecl *BaseVD = Base.dyn_cast<const ValueDecl*>();

  // Additional restrictions apply in a template argument. We only enforce the
  // C++20 restrictions here; additional syntactic and semantic restrictions
  // are applied elsewhere.
  if (isTemplateArgument(Kind)) {
    int InvalidBaseKind = -1;
    StringRef Ident;
    if (Base.is<TypeInfoLValue>())
      InvalidBaseKind = 0;
    else if (isa_and_nonnull<StringLiteral>(BaseE))
      InvalidBaseKind = 1;
    else if (isa_and_nonnull<MaterializeTemporaryExpr>(BaseE) ||
             isa_and_nonnull<LifetimeExtendedTemporaryDecl>(BaseVD)821)
      InvalidBaseKind = 2;
    else if (auto *PE = dyn_cast_or_null<PredefinedExpr>(BaseE)) {
      InvalidBaseKind = 3;
      Ident = PE->getIdentKindName();
    }

    if (InvalidBaseKind != -1) {
      Info.FFDiag(Loc, diag::note_constexpr_invalid_template_arg)
          << IsReferenceType << !Designator.Entries.empty() << InvalidBaseKind
          << Ident;
      return false;
    }
  }

  if (auto *FD = dyn_cast_or_null<FunctionDecl>(BaseVD)) {
    if (FD->isConsteval()) {
      Info.FFDiag(Loc, diag::note_consteval_address_accessible)
          << !Type->isAnyPointerType();
      Info.Note(FD->getLocation(), diag::note_declared_at);
      return false;
    }
  }

  // Check that the object is a global. Note that the fake 'this' object we
  // manufacture when checking potential constant expressions is conservatively
  // assumed to be global here.
  if (!IsGlobalLValue(Base)) {
    if (Info.getLangOpts().CPlusPlus11) {
      const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
      Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
        << IsReferenceType << !Designator.Entries.empty()
        << !!VD << VD;

      auto *VarD = dyn_cast_or_null<VarDecl>(VD);
      if (VarD && VarD->isConstexpr()34.6k) {
        // Non-static local constexpr variables have unintuitive semantics:
        //   constexpr int a = 1;
        //   constexpr const int *p = &a;
        // ... is invalid because the address of 'a' is not constant. Suggest
        // adding a 'static' in this case.
        Info.Note(VarD->getLocation(), diag::note_constexpr_not_static)
            << VarD
            << FixItHint::CreateInsertion(VarD->getBeginLoc(), "static ");
      } else {
        NoteLValueLocation(Info, Base);
      }
    } else {
      Info.FFDiag(Loc);
    }
    // Don't allow references to temporaries to escape.
    return false;
  }
  assert((Info.checkingPotentialConstantExpression() ||
          LVal.getLValueCallIndex() == 0) &&
         "have call index for global lvalue");

  if (Base.is<DynamicAllocLValue>()) {
    Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc)
        << IsReferenceType << !Designator.Entries.empty();
    NoteLValueLocation(Info, Base);
    return false;
  }

  if (BaseVD) {
    if (const VarDecl *Var = dyn_cast<const VarDecl>(BaseVD)) {
      // Check if this is a thread-local variable.
      if (Var->getTLSKind())
        // FIXME: Diagnostic!
        return false;

      // A dllimport variable never acts like a constant, unless we're
      // evaluating a value for use only in name mangling.
      if (!isForManglingOnly(Kind) && Var->hasAttr<DLLImportAttr>()16.1k)
        // FIXME: Diagnostic!
        return false;

      // In CUDA/HIP device compilation, only device side variables have
      // constant addresses.
      if (Info.getCtx().getLangOpts().CUDA &&
          Info.getCtx().getLangOpts().CUDAIsDevice482 &&
          Info.getCtx().CUDAConstantEvalCtx.NoWrongSidedVars239) {
        if ((!Var->hasAttr<CUDADeviceAttr>() &&
             !Var->hasAttr<CUDAConstantAttr>()44 &&
             !Var->getType()->isCUDADeviceBuiltinSurfaceType()18 &&
             !Var->getType()->isCUDADeviceBuiltinTextureType()14) ||
            Var->hasAttr<HIPManagedAttr>()42)
          return false;
      }
    }
    if (const auto *FD = dyn_cast<const FunctionDecl>(BaseVD)) {
      // __declspec(dllimport) must be handled very carefully:
      // We must never initialize an expression with the thunk in C++.
      // Doing otherwise would allow the same id-expression to yield
      // different addresses for the same function in different translation
      // units.  However, this means that we must dynamically initialize the
      // expression with the contents of the import address table at runtime.
      //
      // The C language has no notion of ODR; furthermore, it has no notion of
      // dynamic initialization.  This means that we are permitted to
      // perform initialization with the address of the thunk.
      if (Info.getLangOpts().CPlusPlus && !isForManglingOnly(Kind)9.86k &&
          FD->hasAttr<DLLImportAttr>()9.75k)
        // FIXME: Diagnostic!
        return false;
    }
  } else if (const auto *MTE =
                 dyn_cast_or_null<MaterializeTemporaryExpr>(BaseE)) {
    if (CheckedTemps.insert(MTE).second) {
      QualType TempType = getType(Base);
      if (TempType.isDestructedType()) {
        Info.FFDiag(MTE->getExprLoc(),
                    diag::note_constexpr_unsupported_temporary_nontrivial_dtor)
            << TempType;
        return false;
      }

      APValue *V = MTE->getOrCreateValue(false);
      assert(V && "evasluation result refers to uninitialised temporary");
      if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
                                 Info, MTE->getExprLoc(), TempType, *V,
                                 Kind, SourceLocation(), CheckedTemps))
        return false;
    }
  }

  // Allow address constant expressions to be past-the-end pointers. This is
  // an extension: the standard requires them to point to an object.
  if (!IsReferenceType)
    return true;

  // A reference constant expression must refer to an object.
  if (!Base) {
    // FIXME: diagnostic
    Info.CCEDiag(Loc);
    return true;
  }

  // Does this refer one past the end of some object?
  if (!Designator.Invalid && Designator.isOnePastTheEnd()16.3k) {
    Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
      << !Designator.Entries.empty() << !!BaseVD << BaseVD;
    NoteLValueLocation(Info, Base);
  }

  return true;
}

/// Member pointers are constant expressions unless they point to a
/// non-virtual dllimport member function.
static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
                                                 SourceLocation Loc,
                                                 QualType Type,
                                                 const APValue &Value,
                                                 ConstantExprKind Kind) {
  const ValueDecl *Member = Value.getMemberPointerDecl();
  const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
  if (!FD)
    return true;
  if (FD->isConsteval()) {
    Info.FFDiag(Loc, diag::note_consteval_address_accessible) << /*pointer*/ 0;
    Info.Note(FD->getLocation(), diag::note_declared_at);
    return false;
  }
  return isForManglingOnly(Kind) || FD->isVirtual()911 ||
         !FD->hasAttr<DLLImportAttr>()786;
}

/// Check that this core constant expression is of literal type, and if not,
/// produce an appropriate diagnostic.
static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
                             const LValue *This = nullptr) {
  if (!E->isPRValue() || E->getType()->isLiteralType(Info.Ctx)11.8M)
    return true;

  // C++1y: A constant initializer for an object o [...] may also invoke
  // constexpr constructors for o and its subobjects even if those objects
  // are of non-literal class types.
  //
  // C++11 missed this detail for aggregates, so classes like this:
  //   struct foo_t { union { int i; volatile int j; } u; };
  // are not (obviously) initializable like so:
  //   __attribute__((__require_constant_initialization__))
  //   static const foo_t x = {{0}};
  // because "i" is a subobject with non-literal initialization (due to the
  // volatile member of the union). See:
  //   http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
  // Therefore, we use the C++1y behavior.
  if (This && Info.EvaluatingDecl == This->getLValueBase()19.7k)
    return true;

  // Prvalue constant expressions must be of literal types.
  if (Info.getLangOpts().CPlusPlus11)
    Info.FFDiag(E, diag::note_constexpr_nonliteral)
      << E->getType();
  else
    Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
  return false;
}

static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
                                  EvalInfo &Info, SourceLocation DiagLoc,
                                  QualType Type, const APValue &Value,
                                  ConstantExprKind Kind,
                                  SourceLocation SubobjectLoc,
                                  CheckedTemporaries &CheckedTemps) {
  if (!Value.hasValue()) {
    Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
      << true << Type;
    if (SubobjectLoc.isValid())
      Info.Note(SubobjectLoc, diag::note_constexpr_subobject_declared_here);
    return false;
  }

  // We allow _Atomic(T) to be initialized from anything that T can be
  // initialized from.
  if (const AtomicType *AT = Type->getAs<AtomicType>())
    Type = AT->getValueType();

  // Core issue 1454: For a literal constant expression of array or class type,
  // each subobject of its value shall have been initialized by a constant
  // expression.
  if (Value.isArray()) {
    QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
    for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I87.2k) {
      if (!CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
                                 Value.getArrayInitializedElt(I), Kind,
                                 SubobjectLoc, CheckedTemps))
        return false;
    }
    if (!Value.hasArrayFiller())
      return true;
    return CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
                                 Value.getArrayFiller(), Kind, SubobjectLoc,
                                 CheckedTemps);
  }
  if (Value.isUnion() && Value.getUnionField()1.05k) {
    return CheckEvaluationResult(
        CERK, Info, DiagLoc, Value.getUnionField()->getType(),
        Value.getUnionValue(), Kind, Value.getUnionField()->getLocation(),
        CheckedTemps);
  }
  if (Value.isStruct()) {
    RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
    if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
      unsigned BaseIndex = 0;
      for (const CXXBaseSpecifier &BS : CD->bases()) {
        if (!CheckEvaluationResult(CERK, Info, DiagLoc, BS.getType(),
                                   Value.getStructBase(BaseIndex), Kind,
                                   BS.getBeginLoc(), CheckedTemps))
          return false;
        ++BaseIndex;
      }
    }
    for (const auto *I : RD->fields()) {
      if (I->isUnnamedBitfield())
        continue;

      if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(),
                                 Value.getStructField(I->getFieldIndex()),
                                 Kind, I->getLocation(), CheckedTemps))
        return false;
    }
  }

  if (Value.isLValue() &&
      CERK == CheckEvaluationResultKind::ConstantExpression135k) {
    LValue LVal;
    LVal.setFrom(Info.Ctx, Value);
    return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Kind,
                                         CheckedTemps);
  }

  if (Value.isMemberPointer() &&
      CERK == CheckEvaluationResultKind::ConstantExpression1.57k)
    return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Kind);

  // Everything else is fine.
  return true;
}

/// Check that this core constant expression value is a valid value for a
/// constant expression. If not, report an appropriate diagnostic. Does not
/// check that the expression is of literal type.
static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc,
                                    QualType Type, const APValue &Value,
                                    ConstantExprKind Kind) {
  // Nothing to check for a constant expression of type 'cv void'.
  if (Type->isVoidType())
    return true;

  CheckedTemporaries CheckedTemps;
  return CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
                               Info, DiagLoc, Type, Value, Kind,
                               SourceLocation(), CheckedTemps);
}

/// Check that this evaluated value is fully-initialized and can be loaded by
/// an lvalue-to-rvalue conversion.
static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc,
                                  QualType Type, const APValue &Value) {
  CheckedTemporaries CheckedTemps;
  return CheckEvaluationResult(
      CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value,
      ConstantExprKind::Normal, SourceLocation(), CheckedTemps);
}

/// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless
/// "the allocated storage is deallocated within the evaluation".
static bool CheckMemoryLeaks(EvalInfo &Info) {
  if (!Info.HeapAllocs.empty()) {
    // We can still fold to a constant despite a compile-time memory leak,
    // so long as the heap allocation isn't referenced in the result (we check
    // that in CheckConstantExpression).
    Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr,
                 diag::note_constexpr_memory_leak)
        << unsigned(Info.HeapAllocs.size() - 1);
  }
  return true;
}

static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
  // A null base expression indicates a null pointer.  These are always
  // evaluatable, and they are false unless the offset is zero.
  if (!Value.getLValueBase()) {
    Result = !Value.getLValueOffset().isZero();
    return true;
  }

  // We have a non-null base.  These are generally known to be true, but if it's
  // a weak declaration it can be null at runtime.
  Result = true;
  const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
  return !Decl || !Decl->isWeak()1.02k;
}

static bool HandleConversionToBool(const APValue &Val, bool &Result) {
  switch (Val.getKind()) {
  case APValue::None:
  case APValue::Indeterminate:
    return false;
  case APValue::Int:
    Result = Val.getInt().getBoolValue();
    return true;
  case APValue::FixedPoint:
    Result = Val.getFixedPoint().getBoolValue();
    return true;
  case APValue::Float:
    Result = !Val.getFloat().isZero();
    return true;
  case APValue::ComplexInt:
    Result = Val.getComplexIntReal().getBoolValue() ||
             Val.getComplexIntImag().getBoolValue()2;
    return true;
  case APValue::ComplexFloat:
    Result = !Val.getComplexFloatReal().isZero() ||
             !Val.getComplexFloatImag().isZero()2;
    return true;
  case APValue::LValue:
    return EvalPointerValueAsBool(Val, Result);
  case APValue::MemberPointer:
    Result = Val.getMemberPointerDecl();
    return true;
  case APValue::Vector:
  case APValue::Array:
  case APValue::Struct:
  case APValue::Union:
  case APValue::AddrLabelDiff:
    return false;
  }

  llvm_unreachable("unknown APValue kind");
}

static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
                                       EvalInfo &Info) {
  assert(!E->isValueDependent());
  assert(E->isPRValue() && "missing lvalue-to-rvalue conv in bool condition");
  APValue Val;
  if (!Evaluate(Val, Info, E))
    return false;
  return HandleConversionToBool(Val, Result);
}

template<typename T>
static bool HandleOverflow(EvalInfo &Info, const Expr *E,
                           const T &SrcValue, QualType DestType) {
  Info.CCEDiag(E, diag::note_constexpr_overflow)
    << SrcValue << DestType;
  return Info.noteUndefinedBehavior();
}

static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
                                 QualType SrcType, const APFloat &Value,
                                 QualType DestType, APSInt &Result) {
  unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
  // Determine whether we are converting to unsigned or signed.
  bool DestSigned = DestType->isSignedIntegerOrEnumerationType();

  Result = APSInt(DestWidth, !DestSigned);
  bool ignored;
  if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
      & APFloat::opInvalidOp)
    return HandleOverflow(Info, E, Value, DestType);
  return true;
}

/// Get rounding mode used for evaluation of the specified expression.
/// \param[out] DynamicRM Is set to true is the requested rounding mode is
///                       dynamic.
/// If rounding mode is unknown at compile time, still try to evaluate the
/// expression. If the result is exact, it does not depend on rounding mode.
/// So return "tonearest" mode instead of "dynamic".
static llvm::RoundingMode getActiveRoundingMode(EvalInfo &Info, const Expr *E,
                                                bool &DynamicRM) {
  llvm::RoundingMode RM =
      E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).getRoundingMode();
  DynamicRM = (RM == llvm::RoundingMode::Dynamic);
  if (DynamicRM)
    RM = llvm::RoundingMode::NearestTiesToEven;
  return RM;
}

/// Check if the given evaluation result is allowed for constant evaluation.
static bool checkFloatingPointResult(EvalInfo &Info, const Expr *E,
                                     APFloat::opStatus St) {
  // In a constant context, assume that any dynamic rounding mode or FP
  // exception state matches the default floating-point environment.
  if (Info.InConstantContext)
    return true;

  FPOptions FPO = E->getFPFeaturesInEffect(Info.Ctx.getLangOpts());
  if ((St & APFloat::opInexact) &&
      FPO.getRoundingMode() == llvm::RoundingMode::Dynamic437) {
    // Inexact result means that it depends on rounding mode. If the requested
    // mode is dynamic, the evaluation cannot be made in compile time.
    Info.FFDiag(E, diag::note_constexpr_dynamic_rounding);
    return false;
  }

  if ((St != APFloat::opOK) &&
      (419FPO.getRoundingMode() == llvm::RoundingMode::Dynamic419 ||
       FPO.getFPExceptionMode() != LangOptions::FPE_Ignore ||
       FPO.getAllowFEnvAccess()417)) {
    Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
    return false;
  }

  if ((St & APFloat::opStatus::opInvalidOp) &&
      FPO.getFPExceptionMode() != LangOptions::FPE_Ignore0) {
    // There is no usefully definable result.
    Info.FFDiag(E);
    return false;
  }

  // FIXME: if:
  // - evaluation triggered other FP exception, and
  // - exception mode is not "ignore", and
  // - the expression being evaluated is not a part of global variable
  //   initializer,
  // the evaluation probably need to be rejected.
  return true;
}

static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
                                   QualType SrcType, QualType DestType,
                                   APFloat &Result) {
  assert(isa<CastExpr>(E) || isa<CompoundAssignOperator>(E));
  bool DynamicRM;
  llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM);
  APFloat::opStatus St;
  APFloat Value = Result;
  bool ignored;
  St = Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), RM, &ignored);
  return checkFloatingPointResult(Info, E, St);
}

static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
                                 QualType DestType, QualType SrcType,
                                 const APSInt &Value) {
  unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
  // Figure out if this is a truncate, extend or noop cast.
  // If the input is signed, do a sign extend, noop, or truncate.
  APSInt Result = Value.extOrTrunc(DestWidth);
  Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
  if (DestType->isBooleanType())
    Result = Value.getBoolValue();
  return Result;
}

static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
                                 const FPOptions FPO,
                                 QualType SrcType, const APSInt &Value,
                                 QualType DestType, APFloat &Result) {
  Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
  APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(),
       APFloat::rmNearestTiesToEven);
  if (!Info.InConstantContext && St != llvm::APFloatBase::opOK11.4k &&
      FPO.isFPConstrained()4) {
    Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
    return false;
  }
  return true;
}

static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
                                  APValue &Value, const FieldDecl *FD) {
  assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield");

  if (!Value.isInt()) {
    // Trying to store a pointer-cast-to-integer into a bitfield.
    // FIXME: In this case, we should provide the diagnostic for casting
    // a pointer to an integer.
    assert(Value.isLValue() && "integral value neither int nor lvalue?");
    Info.FFDiag(E);
    return false;
  }

  APSInt &Int = Value.getInt();
  unsigned OldBitWidth = Int.getBitWidth();
  unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
  if (NewBitWidth < OldBitWidth)
    Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
  return true;
}

static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
                                  llvm::APInt &Res) {
  APValue SVal;
  if (!Evaluate(SVal, Info, E))
    return false;
  if (SVal.isInt()) {
    Res = SVal.getInt();
    return true;
  }
  if (SVal.isFloat()) {
    Res = SVal.getFloat().bitcastToAPInt();
    return true;
  }
  if (SVal.isVector()) {
    QualType VecTy = E->getType();
    unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
    QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
    unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
    bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
    Res = llvm::APInt::getZero(VecSize);
    for (unsigned i = 0; i < SVal.getVectorLength(); i++1.22k) {
      APValue &Elt = SVal.getVectorElt(i);
      llvm::APInt EltAsInt;
      if (Elt.isInt()) {
        EltAsInt = Elt.getInt();
      } else if (148Elt.isFloat()148) {
        EltAsInt = Elt.getFloat().bitcastToAPInt();
      } else {
        // Don't try to handle vectors of anything other than int or float
        // (not sure if it's possible to hit this case).
        Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
        return false;
      }
      unsigned BaseEltSize = EltAsInt.getBitWidth();
      if (BigEndian)
        Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
      else
        Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
    }
    return true;
  }
  // Give up if the input isn't an int, float, or vector.  For example, we
  // reject "(v4i16)(intptr_t)&a".
  Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
  return false;
}

/// Perform the given integer operation, which is known to need at most BitWidth
/// bits, and check for overflow in the original type (if that type was not an
/// unsigned type).
template<typename Operation>
static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
                                 const APSInt &LHS, const APSInt &RHS,
                                 unsigned BitWidth, Operation Op,
                                 APSInt &Result) {
  if (LHS.isUnsigned()) {
    Result = Op(LHS, RHS);
    return true;
  }

  APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
  Result = Value.trunc(LHS.getBitWidth());
  if (Result.extend(BitWidth) != Value) {
    if (Info.checkingForUndefinedBehavior())
      Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
                                       diag::warn_integer_constant_overflow)
          << toString(Result, 10) << E->getType();
    return HandleOverflow(Info, E, Value, E->getType());
  }
  return true;
}

/// Perform the given binary integer operation.
static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
                              BinaryOperatorKind Opcode, APSInt RHS,
                              APSInt &Result) {
  switch (Opcode) {
  default:
    Info.FFDiag(E);
    return false;
  case BO_Mul:
    return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
                                std::multiplies<APSInt>(), Result);
  case BO_Add:
    return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
                                std::plus<APSInt>(), Result);
  case BO_Sub:
    return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
                                std::minus<APSInt>(), Result);
  case BO_And: Result = LHS & RHS; return true;
  case BO_Xor: Result = LHS ^ RHS; return true;
  case BO_Or:  Result = LHS | RHS; return true;
  case BO_Div:
  case BO_Rem:
    if (RHS == 0) {
      Info.FFDiag(E, diag::note_expr_divide_by_zero);
      return false;
    }
    Result = (Opcode == BO_Rem ? LHS % RHS7.31k : LHS / RHS661k);
    // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
    // this operation and gives the two's complement result.
    if (RHS.isNegative() && RHS.isAllOnes()7 && LHS.isSigned()7 &&
        LHS.isMinSignedValue()7)
      return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1),
                            E->getType());
    return true;
  case BO_Shl: {
    if (Info.getLangOpts().OpenCL)
      // OpenCL 6.3j: shift values are effectively % word size of LHS.
      RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
                    static_cast<uint64_t>(LHS.getBitWidth() - 1)),
                    RHS.isUnsigned());
    else if (RHS.isSigned() && RHS.isNegative()229k) {
      // During constant-folding, a negative shift is an opposite shift. Such
      // a shift is not a constant expression.
      Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
      RHS = -RHS;
      goto shift_right;
    }
  shift_left:
    // C++11 [expr.shift]p1: Shift width must be less than the bit width of
    // the shifted type.
    unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
    if (SA != RHS) {
      Info.CCEDiag(E, diag::note_constexpr_large_shift)
        << RHS << E->getType() << LHS.getBitWidth();
    } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20173k) {
      // C++11 [expr.shift]p2: A signed left shift must have a non-negative
      // operand, and must not overflow the corresponding unsigned type.
      // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to
      // E1 x 2^E2 module 2^N.
      if (LHS.isNegative())
        Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
      else if (LHS.countLeadingZeros() < SA)
        Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
    }
    Result = LHS << SA;
    return true;
  }
  case BO_Shr: {
    if (Info.getLangOpts().OpenCL)
      // OpenCL 6.3j: shift values are effectively % word size of LHS.
      RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
                    static_cast<uint64_t>(LHS.getBitWidth() - 1)),
                    RHS.isUnsigned());
    else if (RHS.isSigned() && RHS.isNegative()11.0k) {
      // During constant-folding, a negative shift is an opposite shift. Such a
      // shift is not a constant expression.
      Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
      RHS = -RHS;
      goto shift_left;
    }
  shift_right:
    // C++11 [expr.shift]p1: Shift width must be less than the bit width of the
    // shifted type.
    unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
    if (SA != RHS)
      Info.CCEDiag(E, diag::note_constexpr_large_shift)
        << RHS << E->getType() << LHS.getBitWidth();
    Result = LHS >> SA;
    return true;
  }

  case BO_LT: Result = LHS < RHS; return true;
  case BO_GT: Result = LHS > RHS; return true;
  case BO_LE: Result = LHS <= RHS; return true;
  case BO_GE: Result = LHS >= RHS; return true;
  case BO_EQ: Result = LHS == RHS; return true;
  case BO_NE: Result = LHS != RHS; return true;
  case BO_Cmp:
    llvm_unreachable("BO_Cmp should be handled elsewhere");
  }
}

/// Perform the given binary floating-point operation, in-place, on LHS.
static bool handleFloatFloatBinOp(EvalInfo &Info, const BinaryOperator *E,
                                  APFloat &LHS, BinaryOperatorKind Opcode,
                                  const APFloat &RHS) {
  bool DynamicRM;
  llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM);
  APFloat::opStatus St;
  switch (Opcode) {
  default:
    Info.FFDiag(E);
    return false;
  case BO_Mul:
    St = LHS.multiply(RHS, RM);
    break;
  case BO_Add:
    St = LHS.add(RHS, RM);
    break;
  case BO_Sub:
    St = LHS.subtract(RHS, RM);
    break;
  case BO_Div:
    // [expr.mul]p4:
    //   If the second operand of / or % is zero the behavior is undefined.
    if (RHS.isZero())
      Info.CCEDiag(E, diag::note_expr_divide_by_zero);
    St = LHS.divide(RHS, RM);
    break;
  }

  // [expr.pre]p4:
  //   If during the evaluation of an expression, the result is not
  //   mathematically defined [...], the behavior is undefined.
  // FIXME: C++ rules require us to not conform to IEEE 754 here.
  if (LHS.isNaN()) {
    Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
    return Info.noteUndefinedBehavior();
  }

  return checkFloatingPointResult(Info, E, St);
}

static bool handleLogicalOpForVector(const APInt &LHSValue,
                                     BinaryOperatorKind Opcode,
                                     const APInt &RHSValue, APInt &Result) {
  bool LHS = (LHSValue != 0);
  bool RHS = (RHSValue != 0);

  if (Opcode == BO_LAnd)
    Result = LHS && RHS8;
  else
    Result = LHS || RHS8;
  return true;
}
static bool handleLogicalOpForVector(const APFloat &LHSValue,
                                     BinaryOperatorKind Opcode,
                                     const APFloat &RHSValue, APInt &Result) {
  bool LHS = !LHSValue.isZero();
  bool RHS = !RHSValue.isZero();

  if (Opcode == BO_LAnd)
    Result = LHS && RHS24;
  else
    Result = LHS || RHS40;
  return true;
}

static bool handleLogicalOpForVector(const APValue &LHSValue,
                                     BinaryOperatorKind Opcode,
                                     const APValue &RHSValue, APInt &Result) {
  // The result is always an int type, however operands match the first.
  if (LHSValue.getKind() == APValue::Int)
    return handleLogicalOpForVector(LHSValue.getInt(), Opcode,
                                    RHSValue.getInt(), Result);
  assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
  return handleLogicalOpForVector(LHSValue.getFloat(), Opcode,
                                  RHSValue.getFloat(), Result);
}

template <typename APTy>
static bool
handleCompareOpForVectorHelper(const APTy &LHSValue, BinaryOperatorKind Opcode,
                               const APTy &RHSValue, APInt &Result) {
  switch (Opcode) {
  default:
    llvm_unreachable("unsupported binary operator");
  case BO_EQ:
    Result = (LHSValue == RHSValue);
    break;
  case BO_NE:
    Result = (LHSValue != RHSValue);
    break;
  case BO_LT:
    Result = (LHSValue < RHSValue);
    break;
  case BO_GT:
    Result = (LHSValue > RHSValue);
    break;
  case BO_LE:
    Result = (LHSValue <= RHSValue);
    break;
  case BO_GE:
    Result = (LHSValue >= RHSValue);
    break;
  }

  // The boolean operations on these vector types use an instruction that
  // results in a mask of '-1' for the 'truth' value.  Ensure that we negate 1
  // to -1 to make sure that we produce the correct value.
  Result.negate();

  return true;
}

static bool handleCompareOpForVector(const APValue &LHSValue,
                                     BinaryOperatorKind Opcode,
                                     const APValue &RHSValue, APInt &Result) {
  // The result is always an int type, however operands match the first.
  if (LHSValue.getKind() == APValue::Int)
    return handleCompareOpForVectorHelper(LHSValue.getInt(), Opcode,
                                          RHSValue.getInt(), Result);
  assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
  return handleCompareOpForVectorHelper(LHSValue.getFloat(), Opcode,
                                        RHSValue.getFloat(), Result);
}

// Perform binary operations for vector types, in place on the LHS.
static bool handleVectorVectorBinOp(EvalInfo &Info, const BinaryOperator *E,
                                    BinaryOperatorKind Opcode,
                                    APValue &LHSValue,
                                    const APValue &RHSValue) {
  assert(Opcode != BO_PtrMemD && Opcode != BO_PtrMemI &&
         "Operation not supported on vector types");

  const auto *VT = E->getType()->castAs<VectorType>();
  unsigned NumElements = VT->getNumElements();
  QualType EltTy = VT->getElementType();

  // In the cases (typically C as I've observed) where we aren't evaluating
  // constexpr but are checking for cases where the LHS isn't yet evaluatable,
  // just give up.
  if (!LHSValue.isVector()) {
    assert(LHSValue.isLValue() &&
           "A vector result that isn't a vector OR uncalculated LValue");
    Info.FFDiag(E);
    return false;
  }

  assert(LHSValue.getVectorLength() == NumElements &&
         RHSValue.getVectorLength() == NumElements && "Different vector sizes");

  SmallVector<APValue, 4> ResultElements;

  for (unsigned EltNum = 0; EltNum < NumElements; ++EltNum788) {
    APValue LHSElt = LHSValue.getVectorElt(EltNum);
    APValue RHSElt = RHSValue.getVectorElt(EltNum);

    if (EltTy->isIntegerType()) {
      APSInt EltResult{Info.Ctx.getIntWidth(EltTy),
                       EltTy->isUnsignedIntegerType()};
      bool Success = true;

      if (BinaryOperator::isLogicalOp(Opcode))
        Success = handleLogicalOpForVector(LHSElt, Opcode, RHSElt, EltResult);
      else if (BinaryOperator::isComparisonOp(Opcode))
        Success = handleCompareOpForVector(LHSElt, Opcode, RHSElt, EltResult);
      else
        Success = handleIntIntBinOp(Info, E, LHSElt.getInt(), Opcode,
                                    RHSElt.getInt(), EltResult);

      if (!Success) {
        Info.FFDiag(E);
        return false;
      }
      ResultElements.emplace_back(EltResult);

    } else if (128EltTy->isFloatingType()128) {
      assert(LHSElt.getKind() == APValue::Float &&
             RHSElt.getKind() == APValue::Float &&
             "Mismatched LHS/RHS/Result Type");
      APFloat LHSFloat = LHSElt.getFloat();

      if (!handleFloatFloatBinOp(Info, E, LHSFloat, Opcode,
                                 RHSElt.getFloat())) {
        Info.FFDiag(E);
        return false;
      }

      ResultElements.emplace_back(LHSFloat);
    }
  }

  LHSValue = APValue(ResultElements.data(), ResultElements.size());
  return true;
}

/// Cast an lvalue referring to a base subobject to a derived class, by
/// truncating the lvalue's path to the given length.
static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
                               const RecordDecl *TruncatedType,
                               unsigned TruncatedElements) {
  SubobjectDesignator &D = Result.Designator;

  // Check we actually point to a derived class object.
  if (TruncatedElements == D.Entries.size())
    return true;
  assert(TruncatedElements >= D.MostDerivedPathLength &&
         "not casting to a derived class");
  if (!Result.checkSubobject(Info, E, CSK_Derived))
    return false;

  // Truncate the path to the subobject, and remove any derived-to-base offsets.
  const RecordDecl *RD = TruncatedType;
  for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I807) {
    if (RD->isInvalidDecl()) return false0;
    const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
    const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
    if (isVirtualBaseClass(D.Entries[I]))
      Result.Offset -= Layout.getVBaseClassOffset(Base);
    else
      Result.Offset -= Layout.getBaseClassOffset(Base);
    RD = Base;
  }
  D.Entries.resize(TruncatedElements);
  return true;
}

static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
                                   const CXXRecordDecl *Derived,
                                   const CXXRecordDecl *Base,
                                   const ASTRecordLayout *RL = nullptr) {
  if (!RL) {
    if (Derived->isInvalidDecl()) return false0;
    RL = &Info.Ctx.getASTRecordLayout(Derived);
  }

  Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
  Obj.addDecl(Info, E, Base, /*Virtual*/ false);
  return true;
}

static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
                             const CXXRecordDecl *DerivedDecl,
                             const CXXBaseSpecifier *Base) {
  const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();

  if (!Base->isVirtual())
    return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);

  SubobjectDesignator &D = Obj.Designator;
  if (D.Invalid)
    return false;

  // Extract most-derived object and corresponding type.
  DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
  if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
    return false;

  // Find the virtual base class.
  if (DerivedDecl->isInvalidDecl()) return false0;
  const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
  Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
  Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
  return true;
}

static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
                                 QualType Type, LValue &Result) {
  for (CastExpr::path_const_iterator PathI = E->path_begin(),
                                     PathE = E->path_end();
       PathI != PathE; ++PathI8.77k) {
    if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
                          *PathI))
      return false;
    Type = (*PathI)->getType();
  }
  return true;
}

/// Cast an lvalue referring to a derived class to a known base subobject.
static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result,
                            const CXXRecordDecl *DerivedRD,
                            const CXXRecordDecl *BaseRD) {
  CXXBasePaths Paths(/*FindAmbiguities=*/false,
                     /*RecordPaths=*/true, /*DetectVirtual=*/false);
  if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
    llvm_unreachable("Class must be derived from the passed in base class!");

  for (CXXBasePathElement &Elem : Paths.front())
    if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base))
      return false;
  return true;
}

/// Update LVal to refer to the given field, which must be a member of the type
/// currently described by LVal.
static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
                               const FieldDecl *FD,
                               const ASTRecordLayout *RL = nullptr) {
  if (!RL) {
    if (FD->getParent()->isInvalidDecl()) return false3;
    RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
  }

  unsigned I = FD->getFieldIndex();
  LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
  LVal.addDecl(Info, E, FD);
  return true;
}

/// Update LVal to refer to the given indirect field.
static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
                                       LValue &LVal,
                                       const IndirectFieldDecl *IFD) {
  for (const auto *C : IFD->chain())
    if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
      return false;
  return true;
}

/// Get the size of the given type in char units.
static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
                         QualType Type, CharUnits &Size) {
  // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
  // extension.
  if (Type->isVoidType() || Type->isFunctionType()326k) {
    Size = CharUnits::One();
    return true;
  }

  if (Type->isDependentType()) {
    Info.FFDiag(Loc);
    return false;
  }

  if (!Type->isConstantSizeType()) {
    // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
    // FIXME: Better diagnostic.
    Info.FFDiag(Loc);
    return false;
  }

  Size = Info.Ctx.getTypeSizeInChars(Type);
  return true;
}

/// Update a pointer value to model pointer arithmetic.
/// \param Info - Information about the ongoing evaluation.
/// \param E - The expression being evaluated, for diagnostic purposes.
/// \param LVal - The pointer value to be updated.
/// \param EltTy - The pointee type represented by LVal.
/// \param Adjustment - The adjustment, in objects of type EltTy, to add.
static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
                                        LValue &LVal, QualType EltTy,
                                        APSInt Adjustment) {
  CharUnits SizeOfPointee;
  if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
    return false;

  LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
  return true;
}

static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
                                        LValue &LVal, QualType EltTy,
                                        int64_t Adjustment) {
  return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
                                     APSInt::get(Adjustment));
}

/// Update an lvalue to refer to a component of a complex number.
/// \param Info - Information about the ongoing evaluation.
/// \param LVal - The lvalue to be updated.
/// \param EltTy - The complex number's component type.
/// \param Imag - False for the real component, true for the imaginary.
static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
                                       LValue &LVal, QualType EltTy,
                                       bool Imag) {
  if (Imag) {
    CharUnits SizeOfComponent;
    if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
      return false;
    LVal.Offset += SizeOfComponent;
  }
  LVal.addComplex(Info, E, EltTy, Imag);
  return true;
}

/// Try to evaluate the initializer for a variable declaration.
///
/// \param Info   Information about the ongoing evaluation.
/// \param E      An expression to be used when printing diagnostics.
/// \param VD     The variable whose initializer should be obtained.
/// \param Version The version of the variable within the frame.
/// \param Frame  The frame in which the variable was created. Must be null
///               if this variable is not local to the evaluation.
/// \param Result Filled in with a pointer to the value of the variable.
static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
                                const VarDecl *VD, CallStackFrame *Frame,
                                unsigned Version, APValue *&Result) {
  APValue::LValueBase Base(VD, Frame ? Frame->Index290k : 03.28M, Version);

  // If this is a local variable, dig out its value.
  if (Frame) {
    Result = Frame->getTemporary(VD, Version);
    if (Result)
      return true;

    if (!isa<ParmVarDecl>(VD)) {
      // Assume variables referenced within a lambda's call operator that were
      // not declared within the call operator are captures and during checking
      // of a potential constant expression, assume they are unknown constant
      // expressions.
      assert(isLambdaCallOperator(Frame->Callee) &&
             (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&
             "missing value for local variable");
      if (Info.checkingPotentialConstantExpression())
        return false;
      // FIXME: This diagnostic is bogus; we do support captures. Is this code
      // still reachable at all?
      Info.FFDiag(E->getBeginLoc(),
                  diag::note_unimplemented_constexpr_lambda_feature_ast)
          << "captures not currently allowed";
      return false;
    }
  }

  // If we're currently evaluating the initializer of this declaration, use that
  // in-flight value.
  if (Info.EvaluatingDecl == Base) {
    Result = Info.EvaluatingDeclValue;
    return true;
  }

  if (isa<ParmVarDecl>(VD)) {
    // Assume parameters of a potential constant expression are usable in
    // constant expressions.
    if (!Info.checkingPotentialConstantExpression() ||
        !Info.CurrentCall->Callee49.2k ||
        !Info.CurrentCall->Callee->Equals(VD->getDeclContext())49.2k) {
      if (Info.getLangOpts().CPlusPlus11) {
        Info.FFDiag(E, diag::note_constexpr_function_param_value_unknown)
            << VD;
        NoteLValueLocation(Info, Base);
      } else {
        Info.FFDiag(E);
      }
    }
    return false;
  }

  // Dig out the initializer, and use the declaration which it's attached to.
  // FIXME: We should eventually check whether the variable has a reachable
  // initializing declaration.
  const Expr *Init = VD->getAnyInitializer(VD);
  if (!Init) {
    // Don't diagnose during potential constant expression checking; an
    // initializer might be added later.
    if (!Info.checkingPotentialConstantExpression()) {
      Info.FFDiag(E, diag::note_constexpr_var_init_unknown, 1)
        << VD;
      NoteLValueLocation(Info, Base);
    }
    return false;
  }

  if (Init->isValueDependent()) {
    // The DeclRefExpr is not value-dependent, but the variable it refers to
    // has a value-dependent initializer. This should only happen in
    // constant-folding cases, where the variable is not actually of a suitable
    // type for use in a constant expression (otherwise the DeclRefExpr would
    // have been value-dependent too), so diagnose that.
    assert(!VD->mightBeUsableInConstantExpressions(Info.Ctx));
    if (!Info.checkingPotentialConstantExpression()) {
      Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
                         ? diag::note_constexpr_ltor_non_constexpr6
                         : diag::note_constexpr_ltor_non_integral2, 1)
          << VD << VD->getType();
      NoteLValueLocation(Info, Base);
    }
    return false;
  }

  // Check that we can fold the initializer. In C++, we will have already done
  // this in the cases where it matters for conformance.
  if (!VD->evaluateValue()) {
    Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
    NoteLValueLocation(Info, Base);
    return false;
  }

  // Check that the variable is actually usable in constant expressions. For a
  // const integral variable or a reference, we might have a non-constant
  // initializer that we can nonetheless evaluate the initializer for. Such
  // variables are not usable in constant expressions. In C++98, the
  // initializer also syntactically needs to be an ICE.
  //
  // FIXME: We don't diagnose cases that aren't potentially usable in constant
  // expressions here; doing so would regress diagnostics for things like
  // reading from a volatile constexpr variable.
  if ((Info.getLangOpts().CPlusPlus && !VD->hasConstantInitialization()1.33M &&
       VD->mightBeUsableInConstantExpressions(Info.Ctx)450) ||
      (1.33M(1.33MInfo.getLangOpts().CPlusPlus1.33M || Info.getLangOpts().OpenCL1.87k) &&
       !Info.getLangOpts().CPlusPlus111.33M && !VD->hasICEInitializer(Info.Ctx)541)) {
    Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
    NoteLValueLocation(Info, Base);
  }

  // Never use the initializer of a weak variable, not even for constant
  // folding. We can't be sure that this is the definition that will be used.
  if (VD->isWeak()) {
    Info.FFDiag(E, diag::note_constexpr_var_init_weak) << VD;
    NoteLValueLocation(Info, Base);
    return false;
  }

  Result = VD->getEvaluatedValue();
  return true;
}

/// Get the base index of the given base class within an APValue representing
/// the given derived class.
static unsigned getBaseIndex(const CXXRecordDecl *Derived,
                             const CXXRecordDecl *Base) {
  Base = Base->getCanonicalDecl();
  unsigned Index = 0;
  for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
         E = Derived->bases_end(); I != E; ++I, ++Index345) {
    if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
      return Index;
  }

  llvm_unreachable("base class missing from derived class's bases list");
}

/// Extract the value of a character from a string literal.
static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
                                            uint64_t Index) {
  assert(!isa<SourceLocExpr>(Lit) &&
         "SourceLocExpr should have already been converted to a StringLiteral");

  // FIXME: Support MakeStringConstant
  if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
    std::string Str;
    Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
    assert(Index <= Str.size() && "Index too large");
    return APSInt::getUnsigned(Str.c_str()[Index]);
  }

  if (auto PE = dyn_cast<PredefinedExpr>(Lit))
    Lit = PE->getFunctionName();
  const StringLiteral *S = cast<StringLiteral>(Lit);
  const ConstantArrayType *CAT =
      Info.Ctx.getAsConstantArrayType(S->getType());
  assert(CAT && "string literal isn't an array");
  QualType CharType = CAT->getElementType();
  assert(CharType->isIntegerType() && "unexpected character type");

  APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
               CharType->isUnsignedIntegerType());
  if (Index < S->getLength())
    Value = S->getCodeUnit(Index);
  return Value;
}

// Expand a string literal into an array of characters.
//
// FIXME: This is inefficient; we should probably introduce something similar
// to the LLVM ConstantDataArray to make this cheaper.
static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
                                APValue &Result,
                                QualType AllocType = QualType()) {
  const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
      AllocType.isNull() ? S->getType()1.60k : AllocType19);
  assert(CAT && "string literal isn't an array");
  QualType CharType = CAT->getElementType();
  assert(CharType->isIntegerType() && "unexpected character type");

  unsigned Elts = CAT->getSize().getZExtValue();
  Result = APValue(APValue::UninitArray(),
                   std::min(S->getLength(), Elts), Elts);
  APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
               CharType->isUnsignedIntegerType());
  if (Result.hasArrayFiller())
    Result.getArrayFiller() = APValue(Value);
  for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I64.7k) {
    Value = S->getCodeUnit(I);
    Result.getArrayInitializedElt(I) = APValue(Value);
  }
}

// Expand an array so that it has more than Index filled elements.
static void expandArray(APValue &Array, unsigned Index) {
  unsigned Size = Array.getArraySize();
  assert(Index < Size);

  // Always at least double the number of elements for which we store a value.
  unsigned OldElts = Array.getArrayInitializedElts();
  unsigned NewElts = std::max(Index+1, OldElts * 2);
  NewElts = std::min(Size, std::max(NewElts, 8u));

  // Copy the data across.
  APValue NewValue(APValue::UninitArray(), NewElts, Size);
  for (unsigned I = 0; I != OldElts; ++I19.6k)
    NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
  for (unsigned I = OldElts; I != NewElts; ++I49.3k)
    NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
  if (NewValue.hasArrayFiller())
    NewValue.getArrayFiller() = Array.getArrayFiller();
  Array.swap(NewValue);
}

/// Determine whether a type would actually be read by an lvalue-to-rvalue
/// conversion. If it's of class type, we may assume that the copy operation
/// is trivial. Note that this is never true for a union type with fields
/// (because the copy always "reads" the active member) and always true for
/// a non-class type.
static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD);
static bool isReadByLvalueToRvalueConversion(QualType T) {
  CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
  return !RD || isReadByLvalueToRvalueConversion(RD)167;
}
static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD) {
  // FIXME: A trivial copy of a union copies the object representation, even if
  // the union is empty.
  if (RD->isUnion())
    return !RD->field_empty();
  if (RD->isEmpty())
    return false;

  for (auto *Field : RD->fields())
    if (!Field->isUnnamedBitfield() &&
        isReadByLvalueToRvalueConversion(Field->getType())1.67k)
      return true;

  for (auto &BaseSpec : RD->bases())
    if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
      return true;

  return false;
}

/// Diagnose an attempt to read from any unreadable field within the specified
/// type, which might be a class type.
static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK,
                                  QualType T) {
  CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
  if (!RD)
    return false;

  if (!RD->hasMutableFields())
    return false;

  for (auto *Field : RD->fields())19 {
    // If we're actually going to read this field in some way, then it can't
    // be mutable. If we're in a union, then assigning to a mutable field
    // (even an empty one) can change the active member, so that's not OK.
    // FIXME: Add core issue number for the union case.
    if (Field->isMutable() &&
        (22RD->isUnion()22 || isReadByLvalueToRvalueConversion(Field->getType())16)) {
      Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field;
      Info.Note(Field->getLocation(), diag::note_declared_at);
      return true;
    }

    if (diagnoseMutableFields(Info, E, AK, Field->getType()))
      return true;
  }

  for (auto &BaseSpec : RD->bases())
    if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType()))
      return true;

  // All mutable fields were empty, and thus not actually read.
  return false;
}

static bool lifetimeStartedInEvaluation(EvalInfo &Info,
                                        APValue::LValueBase Base,
                                        bool MutableSubobject = false) {
  // A temporary or transient heap allocation we created.
  if (Base.getCallIndex() || Base.is<DynamicAllocLValue>()1.60M)
    return true;

  switch (Info.IsEvaluatingDecl) {
  case EvalInfo::EvaluatingDeclKind::None:
    return false;

  case EvalInfo::EvaluatingDeclKind::Ctor:
    // The variable whose initializer we're evaluating.
    if (Info.EvaluatingDecl == Base)
      return true;

    // A temporary lifetime-extended by the variable whose initializer we're
    // evaluating.
    if (auto *BaseE = Base.dyn_cast<const Expr *>())
      if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE))
        return Info.EvaluatingDecl == BaseMTE->getExtendingDecl();
    return false;

  case EvalInfo::EvaluatingDeclKind::Dtor:
    // C++2a [expr.const]p6:
    //   [during constant destruction] the lifetime of a and its non-mutable
    //   subobjects (but not its mutable subobjects) [are] considered to start
    //   within e.
    if (MutableSubobject || Base != Info.EvaluatingDecl120)
      return false;
    // FIXME: We can meaningfully extend this to cover non-const objects, but
    // we will need special handling: we should be able to access only
    // subobjects of such objects that are themselves declared const.
    QualType T = getType(Base);
    return T.isConstQualified() || T->isReferenceType()48;
  }

  llvm_unreachable("unknown evaluating decl kind");
}

namespace {
/// A handle to a complete object (an object that is not a subobject of
/// another object).
struct CompleteObject {
  /// The identity of the object.
  APValue::LValueBase Base;
  /// The value of the complete object.
  APValue *Value;
  /// The type of the complete object.
  QualType Type;

  CompleteObject() : Value(nullptr) {}
  CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type)
      : Base(Base), Value(Value), Type(Type) {}

  bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const {
    // If this isn't a "real" access (eg, if it's just accessing the type
    // info), allow it. We assume the type doesn't change dynamically for
    // subobjects of constexpr objects (even though we'd hit UB here if it
    // did). FIXME: Is this right?
    if (!isAnyAccess(AK))
      return true;

    // In C++14 onwards, it is permitted to read a mutable member whose
    // lifetime began within the evaluation.
    // FIXME: Should we also allow this in C++11?
    if (!Info.getLangOpts().CPlusPlus14)
      return false;
    return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true);
  }

  explicit operator bool() const { return !Type.isNull(); }
};
} // end anonymous namespace

static QualType getSubobjectType(QualType ObjType, QualType SubobjType,
                                 bool IsMutable = false) {
  // C++ [basic.type.qualifier]p1:
  // - A const object is an object of type const T or a non-mutable subobject
  //   of a const object.
  if (ObjType.isConstQualified() && !IsMutable15.4k)
    SubobjType.addConst();
  // - A volatile object is an object of type const T or a subobject of a
  //   volatile object.
  if (ObjType.isVolatileQualified())
    SubobjType.addVolatile();
  return SubobjType;
}

/// Find the designated sub-object of an rvalue.
template<typename SubobjectHandler>
typename SubobjectHandler::result_type
findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
              const SubobjectDesignator &Sub, SubobjectHandler &handler) {
  if (Sub.Invalid)
    // A diagnostic will have already been produced.
    return handler.failed();
  if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()1.67M) {
    if (Info.getLangOpts().CPlusPlus11)
      Info.FFDiag(E, Sub.isOnePastTheEnd()
                         ? diag::note_constexpr_access_past_end
                         : diag::note_constexpr_access_unsized_array0)
          << handler.AccessKind;
    else
      Info.FFDiag(E);
    return handler.failed();
  }

  APValue *O = Obj.Value;
  QualType ObjType = Obj.Type;
  const FieldDecl *LastField = nullptr;
  const FieldDecl *VolatileField = nullptr;

  // Walk the designator's path to find the subobject.
  for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I84.5k) {
    // Reading an indeterminate value is undefined, but assigning over one is OK.
    if ((O->isAbsent() && !(363handler.AccessKind == AK_Construct363 && I == N30)) ||
        (1.75MO->isIndeterminate()1.75M &&
         !isValidIndeterminateAccess(handler.AccessKind)15.3k)) {
      if (!Info.checkingPotentialConstantExpression())
        Info.FFDiag(E, diag::note_constexpr_access_uninit)
            << handler.AccessKind << O->isIndeterminate();
      return handler.failed();
    }

    // C++ [class.ctor]p5, C++ [class.dtor]p5:
    //    const and volatile semantics are not applied on an object under
    //    {con,de}struction.
    if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()366k) &&
        ObjType->isRecordType()1.39M &&
        Info.isEvaluatingCtorDtor(
            Obj.Base, llvm::makeArrayRef(Sub.Entries.begin(),
                                         Sub.Entries.begin() + I)) !=
                          ConstructionPhase::None) {
      ObjType = Info.Ctx.getCanonicalType(ObjType);
      ObjType.removeLocalConst();
      ObjType.removeLocalVolatile();
    }

    // If this is our last pass, check that the final object type is OK.
    if (I == N || (84.9kI == N - 184.9k && ObjType->isAnyComplexType()77.5k)) {
      // Accesses to volatile objects are prohibited.
      if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)24) {
        if (Info.getLangOpts().CPlusPlus) {
          int DiagKind;
          SourceLocation Loc;
          const NamedDecl *Decl = nullptr;
          if (VolatileField) {
            DiagKind = 2;
            Loc = VolatileField->getLocation();
            Decl = VolatileField;
          } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) {
            DiagKind = 1;
            Loc = VD->getLocation();
            Decl = VD;
          } else {
            DiagKind = 0;
            if (auto *E = Obj.Base.dyn_cast<const Expr *>())
              Loc = E->getExprLoc();
          }
          Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
              << handler.AccessKind << DiagKind << Decl;
          Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind;
        } else {
          Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
        }
        return handler.failed();
      }

      // If we are reading an object of class type, there may still be more
      // things we need to check: if there are any mutable subobjects, we
      // cannot perform this read. (This only happens when performing a trivial
      // copy or assignment.)
      if (ObjType->isRecordType() &&
          !Obj.mayAccessMutableMembers(Info, handler.AccessKind)20.5k &&
          diagnoseMutableFields(Info, E, handler.AccessKind, ObjType)665)
        return handler.failed();
    }

    if (I == N) {
      if (!handler.found(*O, ObjType))
        return false;

      // If we modified a bit-field, truncate it to the right width.
      if (isModification(handler.AccessKind) &&
          LastField58.6k && LastField->isBitField()1.36k &&
          !truncateBitfieldValue(Info, E, *O, LastField)24)
        return false;

      return true;
    }

    LastField = nullptr;
    if (ObjType->isArrayType()) {
      // Next subobject is an array element.
      const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
      assert(CAT && "vla in literal type?");
      uint64_t Index = Sub.Entries[I].getAsArrayIndex();
      if (CAT->getSize().ule(Index)) {
        // Note, it should not be possible to form a pointer with a valid
        // designator which points more than one past the end of the array.
        if (Info.getLangOpts().CPlusPlus11)
          Info.FFDiag(E, diag::note_constexpr_access_past_end)
            << handler.AccessKind;
        else
          Info.FFDiag(E);
        return handler.failed();
      }

      ObjType = CAT->getElementType();

      if (O->getArrayInitializedElts() > Index)
        O = &O->getArrayInitializedElt(Index);
      else if (!isRead(handler.AccessKind)) {
        expandArray(*O, Index);
        O = &O->getArrayInitializedElt(Index);
      } else
        O = &O->getArrayFiller();
    } else if (26.5kObjType->isAnyComplexType()26.5k) {
      // Next subobject is a complex number.
      uint64_t Index = Sub.Entries[I].getAsArrayIndex();
      if (Index > 1) {
        if (Info.getLangOpts().CPlusPlus11)
          Info.FFDiag(E, diag::note_constexpr_access_past_end)
            << handler.AccessKind;
        else
          Info.FFDiag(E);
        return handler.failed();
      }

      ObjType = getSubobjectType(
          ObjType, ObjType->castAs<ComplexType>()->getElementType());

      assert(I == N - 1 && "extracting subobject of scalar?");
      if (O->isComplexInt()) {
        return handler.found(Index ? O->getComplexIntImag()6
                                   : O->getComplexIntReal()6, ObjType);
      } else {
        assert(O->isComplexFloat());
        return handler.found(Index ? O->getComplexFloatImag()6
                                   : O->getComplexFloatReal()6, ObjType);
      }
    } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
      if (Field->isMutable() &&
          !Obj.mayAccessMutableMembers(Info, handler.AccessKind)40) {
        Info.FFDiag(E, diag::note_constexpr_access_mutable, 1)
          << handler.AccessKind << Field;
        Info.Note(Field->getLocation(), diag::note_declared_at);
        return handler.failed();
      }

      // Next subobject is a class, struct or union field.
      RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
      if (RD->isUnion()) {
        const FieldDecl *UnionField = O->getUnionField();
        if (!UnionField ||
            UnionField->getCanonicalDecl() != Field->getCanonicalDecl()992) {
          if (I == N - 1 && handler.AccessKind == AK_Construct297) {
            // Placement new onto an inactive union member makes it active.
            O->setUnion(Field, APValue());
          } else {
            // FIXME: If O->getUnionValue() is absent, report that there's no
            // active union member rather than reporting the prior active union
            // member. We'll need to fix nullptr_t to not use APValue() as its
            // representation first.
            Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
                << handler.AccessKind << Field << !UnionField << UnionField;
            return handler.failed();
          }
        }
        O = &O->getUnionValue();
      } else
        O = &O->getStructField(Field->getFieldIndex());

      ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable());
      LastField = Field;
      if (Field->getType().isVolatileQualified())
        VolatileField = Field;
    } else {
      // Next subobject is a base class.
      const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
      const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
      O = &O->getStructBase(getBaseIndex(Derived, Base));

      ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base));
    }
  }
      // If we modified a bit-field, truncate it to the right width.

Coverage Report

Created: 2022-05-17 06:19