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Diffstat (limited to 'contrib/llvm/tools/clang/lib/AST/ExprConstant.cpp')
| -rw-r--r-- | contrib/llvm/tools/clang/lib/AST/ExprConstant.cpp | 9188 |
1 files changed, 9188 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/AST/ExprConstant.cpp b/contrib/llvm/tools/clang/lib/AST/ExprConstant.cpp new file mode 100644 index 0000000..d1ec7ae --- /dev/null +++ b/contrib/llvm/tools/clang/lib/AST/ExprConstant.cpp @@ -0,0 +1,9188 @@ +//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the 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 "clang/AST/APValue.h" +#include "clang/AST/ASTContext.h" +#include "clang/AST/ASTDiagnostic.h" +#include "clang/AST/CharUnits.h" +#include "clang/AST/Expr.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/SmallString.h" +#include "llvm/Support/raw_ostream.h" +#include <cstring> +#include <functional> + +using namespace clang; +using llvm::APSInt; +using llvm::APFloat; + +static bool IsGlobalLValue(APValue::LValueBase B); + +namespace { + struct LValue; + struct CallStackFrame; + struct EvalInfo; + + static QualType getType(APValue::LValueBase B) { + if (!B) return QualType(); + if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) + return D->getType(); + + const Expr *Base = B.get<const Expr*>(); + + // For a materialized temporary, the type of the temporary we materialized + // may not be the type of the expression. + if (const MaterializeTemporaryExpr *MTE = + dyn_cast<MaterializeTemporaryExpr>(Base)) { + SmallVector<const Expr *, 2> CommaLHSs; + SmallVector<SubobjectAdjustment, 2> Adjustments; + const Expr *Temp = MTE->GetTemporaryExpr(); + const Expr *Inner = Temp->skipRValueSubobjectAdjustments(CommaLHSs, + Adjustments); + // Keep any cv-qualifiers from the reference if we generated a temporary + // for it. + if (Inner != Temp) + return Inner->getType(); + } + + return Base->getType(); + } + + /// Get an LValue path entry, which is known to not be an array index, as a + /// field or base class. + static + APValue::BaseOrMemberType getAsBaseOrMember(APValue::LValuePathEntry E) { + APValue::BaseOrMemberType Value; + Value.setFromOpaqueValue(E.BaseOrMember); + return Value; + } + + /// 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<FieldDecl>(getAsBaseOrMember(E).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<CXXRecordDecl>(getAsBaseOrMember(E).getPointer()); + } + /// Determine whether this LValue path entry for a base class names a virtual + /// base class. + static bool isVirtualBaseClass(APValue::LValuePathEntry E) { + return getAsBaseOrMember(E).getInt(); + } + + /// 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, QualType Base, + ArrayRef<APValue::LValuePathEntry> Path, + uint64_t &ArraySize, QualType &Type) { + unsigned MostDerivedLength = 0; + Type = Base; + for (unsigned I = 0, N = Path.size(); I != N; ++I) { + if (Type->isArrayType()) { + const ConstantArrayType *CAT = + cast<ConstantArrayType>(Ctx.getAsArrayType(Type)); + Type = CAT->getElementType(); + ArraySize = CAT->getSize().getZExtValue(); + MostDerivedLength = I + 1; + } else if (Type->isAnyComplexType()) { + const ComplexType *CT = Type->castAs<ComplexType>(); + Type = CT->getElementType(); + ArraySize = 2; + MostDerivedLength = I + 1; + } else if (const FieldDecl *FD = getAsField(Path[I])) { + Type = FD->getType(); + ArraySize = 0; + MostDerivedLength = I + 1; + } else { + // Path[I] describes a base class. + ArraySize = 0; + } + } + return MostDerivedLength; + } + + // The order of this enum is important for diagnostics. + enum CheckSubobjectKind { + CSK_Base, CSK_Derived, CSK_Field, CSK_ArrayToPointer, CSK_ArrayIndex, + CSK_This, CSK_Real, CSK_Imag + }; + + /// 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. + bool Invalid : 1; + + /// Is this a pointer one past the end of an object? + bool IsOnePastTheEnd : 1; + + /// The length of the path to the most-derived object of which this is a + /// subobject. + unsigned MostDerivedPathLength : 30; + + /// The size of the array of which the most-derived object is an element, or + /// 0 if the most-derived object is not an array element. + 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), MostDerivedPathLength(0), + MostDerivedArraySize(0), MostDerivedType(T) {} + + SubobjectDesignator(ASTContext &Ctx, const APValue &V) + : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false), + MostDerivedPathLength(0), MostDerivedArraySize(0) { + if (!Invalid) { + IsOnePastTheEnd = V.isLValueOnePastTheEnd(); + ArrayRef<PathEntry> VEntries = V.getLValuePath(); + Entries.insert(Entries.end(), VEntries.begin(), VEntries.end()); + if (V.getLValueBase()) + MostDerivedPathLength = + findMostDerivedSubobject(Ctx, getType(V.getLValueBase()), + V.getLValuePath(), MostDerivedArraySize, + MostDerivedType); + } + } + + void setInvalid() { + Invalid = true; + Entries.clear(); + } + + /// Determine whether this is a one-past-the-end pointer. + bool isOnePastTheEnd() const { + assert(!Invalid); + if (IsOnePastTheEnd) + return true; + if (MostDerivedArraySize && + Entries[MostDerivedPathLength - 1].ArrayIndex == MostDerivedArraySize) + return true; + return false; + } + + /// 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); + + /// Update this designator to refer to the first element within this array. + void addArrayUnchecked(const ConstantArrayType *CAT) { + PathEntry Entry; + Entry.ArrayIndex = 0; + Entries.push_back(Entry); + + // This is a most-derived object. + MostDerivedType = CAT->getElementType(); + MostDerivedArraySize = CAT->getSize().getZExtValue(); + 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) { + PathEntry Entry; + APValue::BaseOrMemberType Value(D, Virtual); + Entry.BaseOrMember = Value.getOpaqueValue(); + Entries.push_back(Entry); + + // 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(); + MostDerivedArraySize = 0; + MostDerivedPathLength = Entries.size(); + } + } + /// Update this designator to refer to the given complex component. + void addComplexUnchecked(QualType EltTy, bool Imag) { + PathEntry Entry; + Entry.ArrayIndex = Imag; + Entries.push_back(Entry); + + // This is technically a most-derived object, though in practice this + // is unlikely to matter. + MostDerivedType = EltTy; + MostDerivedArraySize = 2; + MostDerivedPathLength = Entries.size(); + } + void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, uint64_t N); + /// Add N to the address of this subobject. + void adjustIndex(EvalInfo &Info, const Expr *E, uint64_t N) { + if (Invalid) return; + if (MostDerivedPathLength == Entries.size() && MostDerivedArraySize) { + Entries.back().ArrayIndex += N; + if (Entries.back().ArrayIndex > MostDerivedArraySize) { + diagnosePointerArithmetic(Info, E, Entries.back().ArrayIndex); + setInvalid(); + } + 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. + if (IsOnePastTheEnd && N == (uint64_t)-1) + IsOnePastTheEnd = false; + else if (!IsOnePastTheEnd && N == 1) + IsOnePastTheEnd = true; + else if (N != 0) { + diagnosePointerArithmetic(Info, E, uint64_t(IsOnePastTheEnd) + N); + setInvalid(); + } + } + }; + + /// A stack frame in the constexpr call stack. + struct CallStackFrame { + EvalInfo &Info; + + /// Parent - The caller of this stack frame. + CallStackFrame *Caller; + + /// CallLoc - The location of the call expression for this call. + SourceLocation CallLoc; + + /// Callee - The function which was called. + const FunctionDecl *Callee; + + /// Index - The call index of this call. + unsigned Index; + + /// This - The binding for the this pointer in this call, if any. + const LValue *This; + + /// Arguments - Parameter bindings for this function call, indexed by + /// parameters' function scope indices. + APValue *Arguments; + + // Note that we intentionally use std::map here so that references to + // values are stable. + typedef std::map<const void*, APValue> MapTy; + typedef MapTy::const_iterator temp_iterator; + /// Temporaries - Temporary lvalues materialized within this stack frame. + MapTy Temporaries; + + CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, + const FunctionDecl *Callee, const LValue *This, + APValue *Arguments); + ~CallStackFrame(); + + APValue *getTemporary(const void *Key) { + MapTy::iterator I = Temporaries.find(Key); + return I == Temporaries.end() ? nullptr : &I->second; + } + APValue &createTemporary(const void *Key, bool IsLifetimeExtended); + }; + + /// 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; + }; + + /// A partial diagnostic which we might know in advance that we are not going + /// to emit. + class OptionalDiagnostic { + PartialDiagnostic *Diag; + + public: + explicit OptionalDiagnostic(PartialDiagnostic *Diag = nullptr) + : Diag(Diag) {} + + template<typename T> + OptionalDiagnostic &operator<<(const T &v) { + if (Diag) + *Diag << v; + return *this; + } + + OptionalDiagnostic &operator<<(const APSInt &I) { + if (Diag) { + SmallVector<char, 32> Buffer; + I.toString(Buffer); + *Diag << StringRef(Buffer.data(), Buffer.size()); + } + return *this; + } + + OptionalDiagnostic &operator<<(const APFloat &F) { + if (Diag) { + // FIXME: Force the precision of the source value down so we don't + // print digits which are usually useless (we don't really care here if + // we truncate a digit by accident in edge cases). Ideally, + // APFloat::toString would automatically print the shortest + // representation which rounds to the correct value, but it's a bit + // tricky to implement. + unsigned precision = + llvm::APFloat::semanticsPrecision(F.getSemantics()); + precision = (precision * 59 + 195) / 196; + SmallVector<char, 32> Buffer; + F.toString(Buffer, precision); + *Diag << StringRef(Buffer.data(), Buffer.size()); + } + return *this; + } + }; + + /// A cleanup, and a flag indicating whether it is lifetime-extended. + class Cleanup { + llvm::PointerIntPair<APValue*, 1, bool> Value; + + public: + Cleanup(APValue *Val, bool IsLifetimeExtended) + : Value(Val, IsLifetimeExtended) {} + + bool isLifetimeExtended() const { return Value.getInt(); } + void endLifetime() { + *Value.getPointer() = APValue(); + } + }; + + /// 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. + struct EvalInfo { + 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; + + /// 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; + + /// EvaluatingDeclValue - This is the value being constructed for the + /// declaration whose initializer is being evaluated, if any. + APValue *EvaluatingDeclValue; + + /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further + /// notes attached to it will also be stored, otherwise they will not be. + bool HasActiveDiagnostic; + + enum EvaluationMode { + /// Evaluate as a constant expression. Stop if we find that the expression + /// is not a constant expression. + EM_ConstantExpression, + + /// Evaluate as a potential constant expression. Keep going if we hit a + /// construct that we can't evaluate yet (because we don't yet know the + /// value of something) but stop if we hit something that could never be + /// a constant expression. + EM_PotentialConstantExpression, + + /// Fold the expression to a constant. Stop if we hit a side-effect that + /// we can't model. + EM_ConstantFold, + + /// Evaluate the expression looking for integer overflow and similar + /// issues. Don't worry about side-effects, and try to visit all + /// subexpressions. + EM_EvaluateForOverflow, + + /// Evaluate in any way we know how. Don't worry about side-effects that + /// can't be modeled. + EM_IgnoreSideEffects, + + /// 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, + + /// Evaluate as a potential constant expression. Keep going if we hit a + /// construct that we can't evaluate yet (because we don't yet know the + /// value of something) but stop if we hit something that could never be + /// 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_PotentialConstantExpressionUnevaluated + } EvalMode; + + /// Are we checking whether the expression is a potential constant + /// expression? + bool checkingPotentialConstantExpression() const { + return EvalMode == EM_PotentialConstantExpression || + EvalMode == EM_PotentialConstantExpressionUnevaluated; + } + + /// 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 checkingForOverflow() { return EvalMode == EM_EvaluateForOverflow; } + + EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode) + : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr), + CallStackDepth(0), NextCallIndex(1), + StepsLeft(getLangOpts().ConstexprStepLimit), + BottomFrame(*this, SourceLocation(), nullptr, nullptr, nullptr), + EvaluatingDecl((const ValueDecl *)nullptr), + EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false), + EvalMode(Mode) {} + + void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) { + EvaluatingDecl = Base; + EvaluatingDeclValue = &Value; + } + + const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); } + + 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 > 1) + return false; + if (NextCallIndex == 0) { + // NextCallIndex has wrapped around. + Diag(Loc, diag::note_constexpr_call_limit_exceeded); + return false; + } + if (CallStackDepth <= getLangOpts().ConstexprCallDepth) + return true; + Diag(Loc, diag::note_constexpr_depth_limit_exceeded) + << getLangOpts().ConstexprCallDepth; + return false; + } + + CallStackFrame *getCallFrame(unsigned CallIndex) { + assert(CallIndex && "no call index in getCallFrame"); + // We will eventually hit BottomFrame, which has Index 1, so Frame can't + // be null in this loop. + CallStackFrame *Frame = CurrentCall; + while (Frame->Index > CallIndex) + Frame = Frame->Caller; + return (Frame->Index == CallIndex) ? Frame : nullptr; + } + + bool nextStep(const Stmt *S) { + if (!StepsLeft) { + Diag(S->getLocStart(), diag::note_constexpr_step_limit_exceeded); + return false; + } + --StepsLeft; + return true; + } + + private: + /// Add a diagnostic to the diagnostics list. + PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId) { + PartialDiagnostic PD(DiagId, Ctx.getDiagAllocator()); + EvalStatus.Diag->push_back(std::make_pair(Loc, PD)); + return EvalStatus.Diag->back().second; + } + + /// Add notes containing a call stack to the current point of evaluation. + void addCallStack(unsigned Limit); + + public: + /// Diagnose that the evaluation cannot be folded. + OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId + = diag::note_invalid_subexpr_in_const_expr, + unsigned ExtraNotes = 0) { + if (EvalStatus.Diag) { + // 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. + if (!EvalStatus.Diag->empty()) { + switch (EvalMode) { + case EM_ConstantFold: + case EM_IgnoreSideEffects: + case EM_EvaluateForOverflow: + if (!EvalStatus.HasSideEffects) + break; + // We've had side-effects; we want the diagnostic from them, not + // some later problem. + case EM_ConstantExpression: + case EM_PotentialConstantExpression: + case EM_ConstantExpressionUnevaluated: + case EM_PotentialConstantExpressionUnevaluated: + HasActiveDiagnostic = false; + return OptionalDiagnostic(); + } + } + + unsigned CallStackNotes = CallStackDepth - 1; + unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit(); + if (Limit) + CallStackNotes = std::min(CallStackNotes, Limit + 1); + if (checkingPotentialConstantExpression()) + CallStackNotes = 0; + + HasActiveDiagnostic = true; + EvalStatus.Diag->clear(); + EvalStatus.Diag->reserve(1 + ExtraNotes + CallStackNotes); + addDiag(Loc, DiagId); + if (!checkingPotentialConstantExpression()) + addCallStack(Limit); + return OptionalDiagnostic(&(*EvalStatus.Diag)[0].second); + } + HasActiveDiagnostic = false; + return OptionalDiagnostic(); + } + + OptionalDiagnostic Diag(const Expr *E, diag::kind DiagId + = diag::note_invalid_subexpr_in_const_expr, + unsigned ExtraNotes = 0) { + if (EvalStatus.Diag) + return Diag(E->getExprLoc(), DiagId, ExtraNotes); + HasActiveDiagnostic = false; + return OptionalDiagnostic(); + } + + /// Diagnose that the evaluation does not produce a C++11 core constant + /// expression. + /// + /// FIXME: Stop evaluating if we're in EM_ConstantExpression or + /// EM_PotentialConstantExpression mode and we produce one of these. + template<typename LocArg> + OptionalDiagnostic CCEDiag(LocArg Loc, diag::kind DiagId + = diag::note_invalid_subexpr_in_const_expr, + unsigned ExtraNotes = 0) { + // Don't override a previous diagnostic. Don't bother collecting + // diagnostics if we're evaluating for overflow. + if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) { + HasActiveDiagnostic = false; + return OptionalDiagnostic(); + } + return Diag(Loc, DiagId, ExtraNotes); + } + + /// Add a note to a prior diagnostic. + OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId) { + if (!HasActiveDiagnostic) + return OptionalDiagnostic(); + return OptionalDiagnostic(&addDiag(Loc, DiagId)); + } + + /// Add a stack of notes to a prior diagnostic. + void addNotes(ArrayRef<PartialDiagnosticAt> Diags) { + if (HasActiveDiagnostic) { + EvalStatus.Diag->insert(EvalStatus.Diag->end(), + Diags.begin(), Diags.end()); + } + } + + /// Should we continue evaluation after encountering a side-effect that we + /// couldn't model? + bool keepEvaluatingAfterSideEffect() { + switch (EvalMode) { + case EM_PotentialConstantExpression: + case EM_PotentialConstantExpressionUnevaluated: + case EM_EvaluateForOverflow: + case EM_IgnoreSideEffects: + return true; + + case EM_ConstantExpression: + case EM_ConstantExpressionUnevaluated: + case EM_ConstantFold: + return false; + } + 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 as much as possible after encountering a + /// construct which can't be reduced to a value? + bool keepEvaluatingAfterFailure() { + if (!StepsLeft) + return false; + + switch (EvalMode) { + case EM_PotentialConstantExpression: + case EM_PotentialConstantExpressionUnevaluated: + case EM_EvaluateForOverflow: + return true; + + case EM_ConstantExpression: + case EM_ConstantExpressionUnevaluated: + case EM_ConstantFold: + case EM_IgnoreSideEffects: + return false; + } + llvm_unreachable("Missed EvalMode case"); + } + }; + + /// 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_ConstantExpression || + Info.EvalMode == EvalInfo::EM_ConstantExpressionUnevaluated)) + Info.EvalMode = EvalInfo::EM_ConstantFold; + } + void keepDiagnostics() { Enabled = false; } + ~FoldConstant() { + if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() && + !Info.EvalStatus.HasSideEffects) + Info.EvalStatus.Diag->clear(); + Info.EvalMode = OldMode; + } + }; + + /// RAII object used to suppress diagnostics and side-effects from a + /// speculative evaluation. + class SpeculativeEvaluationRAII { + EvalInfo &Info; + Expr::EvalStatus Old; + + public: + SpeculativeEvaluationRAII(EvalInfo &Info, + SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr) + : Info(Info), Old(Info.EvalStatus) { + Info.EvalStatus.Diag = NewDiag; + // If we're speculatively evaluating, we may have skipped over some + // evaluations and missed out a side effect. + Info.EvalStatus.HasSideEffects = true; + } + ~SpeculativeEvaluationRAII() { + Info.EvalStatus = Old; + } + }; + + /// RAII object wrapping a full-expression or block scope, and handling + /// the ending of the lifetime of temporaries created within it. + template<bool IsFullExpression> + class ScopeRAII { + EvalInfo &Info; + unsigned OldStackSize; + public: + ScopeRAII(EvalInfo &Info) + : Info(Info), OldStackSize(Info.CleanupStack.size()) {} + ~ScopeRAII() { + // Body moved to a static method to encourage the compiler to inline away + // instances of this class. + cleanup(Info, OldStackSize); + } + private: + static void cleanup(EvalInfo &Info, unsigned OldStackSize) { + unsigned NewEnd = OldStackSize; + for (unsigned I = OldStackSize, N = Info.CleanupStack.size(); + I != N; ++I) { + if (IsFullExpression && Info.CleanupStack[I].isLifetimeExtended()) { + // Full-expression cleanup of a lifetime-extended temporary: nothing + // to do, just move this cleanup to the right place in the stack. + std::swap(Info.CleanupStack[I], Info.CleanupStack[NewEnd]); + ++NewEnd; + } else { + // End the lifetime of the object. + Info.CleanupStack[I].endLifetime(); + } + } + Info.CleanupStack.erase(Info.CleanupStack.begin() + NewEnd, + Info.CleanupStack.end()); + } + }; + typedef ScopeRAII<false> BlockScopeRAII; + typedef ScopeRAII<true> FullExpressionRAII; +} + +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; + } + return true; +} + +void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info, + const Expr *E, uint64_t N) { + if (MostDerivedPathLength == Entries.size() && MostDerivedArraySize) + Info.CCEDiag(E, diag::note_constexpr_array_index) + << static_cast<int>(N) << /*array*/ 0 + << static_cast<unsigned>(MostDerivedArraySize); + else + Info.CCEDiag(E, diag::note_constexpr_array_index) + << static_cast<int>(N) << /*non-array*/ 1; + setInvalid(); +} + +CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, + const FunctionDecl *Callee, const LValue *This, + APValue *Arguments) + : Info(Info), Caller(Info.CurrentCall), CallLoc(CallLoc), Callee(Callee), + Index(Info.NextCallIndex++), This(This), Arguments(Arguments) { + Info.CurrentCall = this; + ++Info.CallStackDepth; +} + +CallStackFrame::~CallStackFrame() { + assert(Info.CurrentCall == this && "calls retired out of order"); + --Info.CallStackDepth; + Info.CurrentCall = Caller; +} + +APValue &CallStackFrame::createTemporary(const void *Key, + bool IsLifetimeExtended) { + APValue &Result = Temporaries[Key]; + assert(Result.isUninit() && "temporary created multiple times"); + Info.CleanupStack.push_back(Cleanup(&Result, IsLifetimeExtended)); + return Result; +} + +static void describeCall(CallStackFrame *Frame, raw_ostream &Out); + +void EvalInfo::addCallStack(unsigned Limit) { + // Determine which calls to skip, if any. + unsigned ActiveCalls = CallStackDepth - 1; + unsigned SkipStart = ActiveCalls, SkipEnd = SkipStart; + if (Limit && Limit < ActiveCalls) { + SkipStart = Limit / 2 + Limit % 2; + SkipEnd = ActiveCalls - Limit / 2; + } + + // Walk the call stack and add the diagnostics. + unsigned CallIdx = 0; + for (CallStackFrame *Frame = CurrentCall; Frame != &BottomFrame; + Frame = Frame->Caller, ++CallIdx) { + // Skip this call? + if (CallIdx >= SkipStart && CallIdx < SkipEnd) { + if (CallIdx == SkipStart) { + // Note that we're skipping calls. + addDiag(Frame->CallLoc, diag::note_constexpr_calls_suppressed) + << unsigned(ActiveCalls - Limit); + } + continue; + } + + SmallVector<char, 128> Buffer; + llvm::raw_svector_ostream Out(Buffer); + describeCall(Frame, Out); + addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str(); + } +} + +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; + unsigned CallIndex; + SubobjectDesignator Designator; + + const APValue::LValueBase getLValueBase() const { return Base; } + CharUnits &getLValueOffset() { return Offset; } + const CharUnits &getLValueOffset() const { return Offset; } + unsigned getLValueCallIndex() const { return CallIndex; } + SubobjectDesignator &getLValueDesignator() { return Designator; } + const SubobjectDesignator &getLValueDesignator() const { return Designator;} + + void moveInto(APValue &V) const { + if (Designator.Invalid) + V = APValue(Base, Offset, APValue::NoLValuePath(), CallIndex); + else + V = APValue(Base, Offset, Designator.Entries, + Designator.IsOnePastTheEnd, CallIndex); + } + void setFrom(ASTContext &Ctx, const APValue &V) { + assert(V.isLValue()); + Base = V.getLValueBase(); + Offset = V.getLValueOffset(); + CallIndex = V.getLValueCallIndex(); + Designator = SubobjectDesignator(Ctx, V); + } + + void set(APValue::LValueBase B, unsigned I = 0) { + Base = B; + Offset = CharUnits::Zero(); + CallIndex = I; + Designator = SubobjectDesignator(getType(B)); + } + + // Check that this LValue is not based on a null pointer. If it is, produce + // a diagnostic and mark the designator as invalid. + bool checkNullPointer(EvalInfo &Info, const Expr *E, + CheckSubobjectKind CSK) { + if (Designator.Invalid) + return false; + if (!Base) { + Info.CCEDiag(E, diag::note_constexpr_null_subobject) + << CSK; + Designator.setInvalid(); + return false; + } + return true; + } + + // 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) { + // Outside C++11, do not build a designator referring to a subobject of + // any object: we won't use such a designator for anything. + if (!Info.getLangOpts().CPlusPlus11) + Designator.setInvalid(); + return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) && + Designator.checkSubobject(Info, E, CSK); + } + + void addDecl(EvalInfo &Info, const Expr *E, + const Decl *D, bool Virtual = false) { + if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base)) + Designator.addDeclUnchecked(D, Virtual); + } + 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_Imag : CSK_Real)) + Designator.addComplexUnchecked(EltTy, Imag); + } + void adjustIndex(EvalInfo &Info, const Expr *E, uint64_t N) { + if (N && checkNullPointer(Info, E, CSK_ArrayIndex)) + Designator.adjustIndex(Info, E, N); + } + }; + + struct MemberPtr { + MemberPtr() {} + explicit MemberPtr(const ValueDecl *Decl) : + DeclAndIsDerivedMember(Decl, false), Path() {} + + /// 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); +static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info); +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, APValue &Result, EvalInfo &Info); + +//===----------------------------------------------------------------------===// +// Misc utilities +//===----------------------------------------------------------------------===// + +/// Produce a string describing the given constexpr call. +static void describeCall(CallStackFrame *Frame, raw_ostream &Out) { + unsigned ArgIndex = 0; + bool IsMemberCall = isa<CXXMethodDecl>(Frame->Callee) && + !isa<CXXConstructorDecl>(Frame->Callee) && + cast<CXXMethodDecl>(Frame->Callee)->isInstance(); + + if (!IsMemberCall) + Out << *Frame->Callee << '('; + + if (Frame->This && IsMemberCall) { + APValue Val; + Frame->This->moveInto(Val); + Val.printPretty(Out, Frame->Info.Ctx, + Frame->This->Designator.MostDerivedType); + // FIXME: Add parens around Val if needed. + Out << "->" << *Frame->Callee << '('; + IsMemberCall = false; + } + + for (FunctionDecl::param_const_iterator I = Frame->Callee->param_begin(), + E = Frame->Callee->param_end(); I != E; ++I, ++ArgIndex) { + if (ArgIndex > (unsigned)IsMemberCall) + Out << ", "; + + const ParmVarDecl *Param = *I; + const APValue &Arg = Frame->Arguments[ArgIndex]; + Arg.printPretty(Out, Frame->Info.Ctx, Param->getType()); + + if (ArgIndex == 0 && IsMemberCall) + Out << "->" << *Frame->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) { + 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; +} + +/// Sign- or zero-extend a value to 64 bits. If it's already 64 bits, just +/// return its existing value. +static int64_t getExtValue(const APSInt &Value) { + return Value.isSigned() ? Value.getSExtValue() + : static_cast<int64_t>(Value.getZExtValue()); +} + +/// Should this call expression be treated as a string literal? +static bool IsStringLiteralCall(const CallExpr *E) { + unsigned Builtin = E->getBuiltinCallee(); + return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString || + Builtin == Builtin::BI__builtin___NSStringMakeConstantString); +} + +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 true; + + 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(); + // ... the address of a function, + return isa<FunctionDecl>(D); + } + + 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(); + } + 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: + case Expr::CXXTypeidExprClass: + case Expr::CXXUuidofExprClass: + return true; + case Expr::CallExprClass: + return IsStringLiteralCall(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(); + 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 void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) { + assert(Base && "no location for a null lvalue"); + const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); + if (VD) + Info.Note(VD->getLocation(), diag::note_declared_at); + else + Info.Note(Base.get<const Expr*>()->getExprLoc(), + diag::note_constexpr_temporary_here); +} + +/// 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) { + bool IsReferenceType = Type->isReferenceType(); + + APValue::LValueBase Base = LVal.getLValueBase(); + const SubobjectDesignator &Designator = LVal.getLValueDesignator(); + + // 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.Diag(Loc, diag::note_constexpr_non_global, 1) + << IsReferenceType << !Designator.Entries.empty() + << !!VD << VD; + NoteLValueLocation(Info, Base); + } else { + Info.Diag(Loc); + } + // Don't allow references to temporaries to escape. + return false; + } + assert((Info.checkingPotentialConstantExpression() || + LVal.getLValueCallIndex() == 0) && + "have call index for global lvalue"); + + if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) { + if (const VarDecl *Var = dyn_cast<const VarDecl>(VD)) { + // Check if this is a thread-local variable. + if (Var->getTLSKind()) + return false; + + // A dllimport variable never acts like a constant. + if (Var->hasAttr<DLLImportAttr>()) + return false; + } + if (const auto *FD = dyn_cast<const FunctionDecl>(VD)) { + // __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 && FD->hasAttr<DLLImportAttr>()) + 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()) { + const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); + Info.Diag(Loc, diag::note_constexpr_past_end, 1) + << !Designator.Entries.empty() << !!VD << VD; + NoteLValueLocation(Info, Base); + } + + return true; +} + +/// 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->isRValue() || E->getType()->isLiteralType(Info.Ctx)) + 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. + if (Info.getLangOpts().CPlusPlus14 && This && + Info.EvaluatingDecl == This->getLValueBase()) + return true; + + // Prvalue constant expressions must be of literal types. + if (Info.getLangOpts().CPlusPlus11) + Info.Diag(E, diag::note_constexpr_nonliteral) + << E->getType(); + else + Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); + return false; +} + +/// 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) { + if (Value.isUninit()) { + Info.Diag(DiagLoc, diag::note_constexpr_uninitialized) + << true << Type; + 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; ++I) { + if (!CheckConstantExpression(Info, DiagLoc, EltTy, + Value.getArrayInitializedElt(I))) + return false; + } + if (!Value.hasArrayFiller()) + return true; + return CheckConstantExpression(Info, DiagLoc, EltTy, + Value.getArrayFiller()); + } + if (Value.isUnion() && Value.getUnionField()) { + return CheckConstantExpression(Info, DiagLoc, + Value.getUnionField()->getType(), + Value.getUnionValue()); + } + if (Value.isStruct()) { + RecordDecl *RD = Type->castAs<RecordType>()->getDecl(); + if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) { + unsigned BaseIndex = 0; + for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), + End = CD->bases_end(); I != End; ++I, ++BaseIndex) { + if (!CheckConstantExpression(Info, DiagLoc, I->getType(), + Value.getStructBase(BaseIndex))) + return false; + } + } + for (const auto *I : RD->fields()) { + if (!CheckConstantExpression(Info, DiagLoc, I->getType(), + Value.getStructField(I->getFieldIndex()))) + return false; + } + } + + if (Value.isLValue()) { + LValue LVal; + LVal.setFrom(Info.Ctx, Value); + return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal); + } + + // Everything else is fine. + return true; +} + +static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) { + return LVal.Base.dyn_cast<const ValueDecl*>(); +} + +static bool IsLiteralLValue(const LValue &Value) { + if (Value.CallIndex) + return false; + const Expr *E = Value.Base.dyn_cast<const Expr*>(); + return E && !isa<MaterializeTemporaryExpr>(E); +} + +static bool IsWeakLValue(const LValue &Value) { + const ValueDecl *Decl = GetLValueBaseDecl(Value); + return Decl && Decl->isWeak(); +} + +static bool isZeroSized(const LValue &Value) { + const ValueDecl *Decl = GetLValueBaseDecl(Value); + if (Decl && isa<VarDecl>(Decl)) { + QualType Ty = Decl->getType(); + if (Ty->isArrayType()) + return Ty->isIncompleteType() || + Decl->getASTContext().getTypeSize(Ty) == 0; + } + return false; +} + +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(); +} + +static bool HandleConversionToBool(const APValue &Val, bool &Result) { + switch (Val.getKind()) { + case APValue::Uninitialized: + return false; + case APValue::Int: + Result = Val.getInt().getBoolValue(); + return true; + case APValue::Float: + Result = !Val.getFloat().isZero(); + return true; + case APValue::ComplexInt: + Result = Val.getComplexIntReal().getBoolValue() || + Val.getComplexIntImag().getBoolValue(); + return true; + case APValue::ComplexFloat: + Result = !Val.getComplexFloatReal().isZero() || + !Val.getComplexFloatImag().isZero(); + 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->isRValue() && "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 void HandleOverflow(EvalInfo &Info, const Expr *E, + const T &SrcValue, QualType DestType) { + Info.CCEDiag(E, diag::note_constexpr_overflow) + << SrcValue << DestType; +} + +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) + HandleOverflow(Info, E, Value, DestType); + return true; +} + +static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E, + QualType SrcType, QualType DestType, + APFloat &Result) { + APFloat Value = Result; + bool ignored; + if (Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), + APFloat::rmNearestTiesToEven, &ignored) + & APFloat::opOverflow) + HandleOverflow(Info, E, Value, DestType); + return true; +} + +static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E, + QualType DestType, QualType SrcType, + APSInt &Value) { + unsigned DestWidth = Info.Ctx.getIntWidth(DestType); + APSInt Result = Value; + // Figure out if this is a truncate, extend or noop cast. + // If the input is signed, do a sign extend, noop, or truncate. + Result = Result.extOrTrunc(DestWidth); + Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType()); + return Result; +} + +static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E, + QualType SrcType, const APSInt &Value, + QualType DestType, APFloat &Result) { + Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1); + if (Result.convertFromAPInt(Value, Value.isSigned(), + APFloat::rmNearestTiesToEven) + & APFloat::opOverflow) + HandleOverflow(Info, E, Value, DestType); + 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.Diag(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::getNullValue(VecSize); + for (unsigned i = 0; i < SVal.getVectorLength(); i++) { + APValue &Elt = SVal.getVectorElt(i); + llvm::APInt EltAsInt; + if (Elt.isInt()) { + EltAsInt = Elt.getInt(); + } else if (Elt.isFloat()) { + 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.Diag(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.Diag(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 APSInt CheckedIntArithmetic(EvalInfo &Info, const Expr *E, + const APSInt &LHS, const APSInt &RHS, + unsigned BitWidth, Operation Op) { + if (LHS.isUnsigned()) + return Op(LHS, RHS); + + APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false); + APSInt Result = Value.trunc(LHS.getBitWidth()); + if (Result.extend(BitWidth) != Value) { + if (Info.checkingForOverflow()) + Info.Ctx.getDiagnostics().Report(E->getExprLoc(), + diag::warn_integer_constant_overflow) + << Result.toString(10) << E->getType(); + else + HandleOverflow(Info, E, Value, E->getType()); + } + return Result; +} + +/// 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.Diag(E); + return false; + case BO_Mul: + Result = CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2, + std::multiplies<APSInt>()); + return true; + case BO_Add: + Result = CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, + std::plus<APSInt>()); + return true; + case BO_Sub: + Result = CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, + std::minus<APSInt>()); + return true; + 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.Diag(E, diag::note_expr_divide_by_zero); + return false; + } + // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. + if (RHS.isNegative() && RHS.isAllOnesValue() && + LHS.isSigned() && LHS.isMinSignedValue()) + HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType()); + Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS); + 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()) { + // 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()) { + // C++11 [expr.shift]p2: A signed left shift must have a non-negative + // operand, and must not overflow the corresponding unsigned type. + 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()) { + // 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; + } +} + +/// Perform the given binary floating-point operation, in-place, on LHS. +static bool handleFloatFloatBinOp(EvalInfo &Info, const Expr *E, + APFloat &LHS, BinaryOperatorKind Opcode, + const APFloat &RHS) { + switch (Opcode) { + default: + Info.Diag(E); + return false; + case BO_Mul: + LHS.multiply(RHS, APFloat::rmNearestTiesToEven); + break; + case BO_Add: + LHS.add(RHS, APFloat::rmNearestTiesToEven); + break; + case BO_Sub: + LHS.subtract(RHS, APFloat::rmNearestTiesToEven); + break; + case BO_Div: + LHS.divide(RHS, APFloat::rmNearestTiesToEven); + break; + } + + if (LHS.isInfinity() || LHS.isNaN()) + Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN(); + 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; ++I) { + if (RD->isInvalidDecl()) return false; + 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 false; + 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 false; + 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; ++PathI) { + if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(), + *PathI)) + return false; + Type = (*PathI)->getType(); + } + 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 false; + RL = &Info.Ctx.getASTRecordLayout(FD->getParent()); + } + + unsigned I = FD->getFieldIndex(); + LVal.Offset += 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()) { + Size = CharUnits::One(); + return true; + } + + if (!Type->isConstantSizeType()) { + // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2. + // FIXME: Better diagnostic. + Info.Diag(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, + int64_t Adjustment) { + CharUnits SizeOfPointee; + if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee)) + return false; + + // Compute the new offset in the appropriate width. + LVal.Offset += Adjustment * SizeOfPointee; + LVal.adjustIndex(Info, E, Adjustment); + return true; +} + +/// 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 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, + APValue *&Result) { + // If this is a parameter to an active constexpr function call, perform + // argument substitution. + if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) { + // Assume arguments of a potential constant expression are unknown + // constant expressions. + if (Info.checkingPotentialConstantExpression()) + return false; + if (!Frame || !Frame->Arguments) { + Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); + return false; + } + Result = &Frame->Arguments[PVD->getFunctionScopeIndex()]; + return true; + } + + // If this is a local variable, dig out its value. + if (Frame) { + Result = Frame->getTemporary(VD); + assert(Result && "missing value for local variable"); + return true; + } + + // Dig out the initializer, and use the declaration which it's attached to. + const Expr *Init = VD->getAnyInitializer(VD); + if (!Init || Init->isValueDependent()) { + // If we're checking a potential constant expression, the variable could be + // initialized later. + if (!Info.checkingPotentialConstantExpression()) + Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); + return false; + } + + // If we're currently evaluating the initializer of this declaration, use that + // in-flight value. + if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) { + Result = Info.EvaluatingDeclValue; + return true; + } + + // Never evaluate the initializer of a weak variable. We can't be sure that + // this is the definition which will be used. + if (VD->isWeak()) { + Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); + 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. + SmallVector<PartialDiagnosticAt, 8> Notes; + if (!VD->evaluateValue(Notes)) { + Info.Diag(E, diag::note_constexpr_var_init_non_constant, + Notes.size() + 1) << VD; + Info.Note(VD->getLocation(), diag::note_declared_at); + Info.addNotes(Notes); + return false; + } else if (!VD->checkInitIsICE()) { + Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, + Notes.size() + 1) << VD; + Info.Note(VD->getLocation(), diag::note_declared_at); + Info.addNotes(Notes); + } + + Result = VD->getEvaluatedValue(); + return true; +} + +static bool IsConstNonVolatile(QualType T) { + Qualifiers Quals = T.getQualifiers(); + return Quals.hasConst() && !Quals.hasVolatile(); +} + +/// 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, ++Index) { + 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) { + // FIXME: Support ObjCEncodeExpr, MakeStringConstant + 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. +static void expandStringLiteral(EvalInfo &Info, const Expr *Lit, + APValue &Result) { + 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"); + + 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; ++I) { + 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; ++I) + NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I)); + for (unsigned I = OldElts; I != NewElts; ++I) + 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(QualType T) { + CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); + if (!RD || (RD->isUnion() && !RD->field_empty())) + return true; + if (RD->isEmpty()) + return false; + + for (auto *Field : RD->fields()) + if (isReadByLvalueToRvalueConversion(Field->getType())) + 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 diagnoseUnreadableFields(EvalInfo &Info, const Expr *E, + QualType T) { + CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); + if (!RD) + return false; + + if (!RD->hasMutableFields()) + return false; + + for (auto *Field : RD->fields()) { + // 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() && + (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) { + Info.Diag(E, diag::note_constexpr_ltor_mutable, 1) << Field; + Info.Note(Field->getLocation(), diag::note_declared_at); + return true; + } + + if (diagnoseUnreadableFields(Info, E, Field->getType())) + return true; + } + + for (auto &BaseSpec : RD->bases()) + if (diagnoseUnreadableFields(Info, E, BaseSpec.getType())) + return true; + + // All mutable fields were empty, and thus not actually read. + return false; +} + +/// Kinds of access we can perform on an object, for diagnostics. +enum AccessKinds { + AK_Read, + AK_Assign, + AK_Increment, + AK_Decrement +}; + +/// A handle to a complete object (an object that is not a subobject of +/// another object). +struct CompleteObject { + /// The value of the complete object. + APValue *Value; + /// The type of the complete object. + QualType Type; + + CompleteObject() : Value(nullptr) {} + CompleteObject(APValue *Value, QualType Type) + : Value(Value), Type(Type) { + assert(Value && "missing value for complete object"); + } + + explicit operator bool() const { return Value; } +}; + +/// 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()) { + if (Info.getLangOpts().CPlusPlus11) + Info.Diag(E, diag::note_constexpr_access_past_end) + << handler.AccessKind; + else + Info.Diag(E); + return handler.failed(); + } + + APValue *O = Obj.Value; + QualType ObjType = Obj.Type; + const FieldDecl *LastField = nullptr; + + // Walk the designator's path to find the subobject. + for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) { + if (O->isUninit()) { + if (!Info.checkingPotentialConstantExpression()) + Info.Diag(E, diag::note_constexpr_access_uninit) << handler.AccessKind; + return handler.failed(); + } + + if (I == N) { + // 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() && handler.AccessKind == AK_Read && + diagnoseUnreadableFields(Info, E, ObjType)) + return handler.failed(); + + if (!handler.found(*O, ObjType)) + return false; + + // If we modified a bit-field, truncate it to the right width. + if (handler.AccessKind != AK_Read && + LastField && LastField->isBitField() && + !truncateBitfieldValue(Info, E, *O, LastField)) + 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].ArrayIndex; + 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.Diag(E, diag::note_constexpr_access_past_end) + << handler.AccessKind; + else + Info.Diag(E); + return handler.failed(); + } + + ObjType = CAT->getElementType(); + + // An array object is represented as either an Array APValue or as an + // LValue which refers to a string literal. + if (O->isLValue()) { + assert(I == N - 1 && "extracting subobject of character?"); + assert(!O->hasLValuePath() || O->getLValuePath().empty()); + if (handler.AccessKind != AK_Read) + expandStringLiteral(Info, O->getLValueBase().get<const Expr *>(), + *O); + else + return handler.foundString(*O, ObjType, Index); + } + + if (O->getArrayInitializedElts() > Index) + O = &O->getArrayInitializedElt(Index); + else if (handler.AccessKind != AK_Read) { + expandArray(*O, Index); + O = &O->getArrayInitializedElt(Index); + } else + O = &O->getArrayFiller(); + } else if (ObjType->isAnyComplexType()) { + // Next subobject is a complex number. + uint64_t Index = Sub.Entries[I].ArrayIndex; + if (Index > 1) { + if (Info.getLangOpts().CPlusPlus11) + Info.Diag(E, diag::note_constexpr_access_past_end) + << handler.AccessKind; + else + Info.Diag(E); + return handler.failed(); + } + + bool WasConstQualified = ObjType.isConstQualified(); + ObjType = ObjType->castAs<ComplexType>()->getElementType(); + if (WasConstQualified) + ObjType.addConst(); + + assert(I == N - 1 && "extracting subobject of scalar?"); + if (O->isComplexInt()) { + return handler.found(Index ? O->getComplexIntImag() + : O->getComplexIntReal(), ObjType); + } else { + assert(O->isComplexFloat()); + return handler.found(Index ? O->getComplexFloatImag() + : O->getComplexFloatReal(), ObjType); + } + } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) { + if (Field->isMutable() && handler.AccessKind == AK_Read) { + Info.Diag(E, diag::note_constexpr_ltor_mutable, 1) + << 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()) { + Info.Diag(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()); + + bool WasConstQualified = ObjType.isConstQualified(); + ObjType = Field->getType(); + if (WasConstQualified && !Field->isMutable()) + ObjType.addConst(); + + if (ObjType.isVolatileQualified()) { + if (Info.getLangOpts().CPlusPlus) { + // FIXME: Include a description of the path to the volatile subobject. + Info.Diag(E, diag::note_constexpr_access_volatile_obj, 1) + << handler.AccessKind << 2 << Field; + Info.Note(Field->getLocation(), diag::note_declared_at); + } else { + Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); + } + return handler.failed(); + } + + LastField = 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)); + + bool WasConstQualified = ObjType.isConstQualified(); + ObjType = Info.Ctx.getRecordType(Base); + if (WasConstQualified) + ObjType.addConst(); + } + } +} + +namespace { +struct ExtractSubobjectHandler { + EvalInfo &Info; + APValue &Result; + + static const AccessKinds AccessKind = AK_Read; + + typedef bool result_type; + bool failed() { return false; } + bool found(APValue &Subobj, QualType SubobjType) { + Result = Subobj; + return true; + } + bool found(APSInt &Value, QualType SubobjType) { + Result = APValue(Value); + return true; + } + bool found(APFloat &Value, QualType SubobjType) { + Result = APValue(Value); + return true; + } + bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { + Result = APValue(extractStringLiteralCharacter( + Info, Subobj.getLValueBase().get<const Expr *>(), Character)); + return true; + } +}; +} // end anonymous namespace + +const AccessKinds ExtractSubobjectHandler::AccessKind; + +/// Extract the designated sub-object of an rvalue. +static bool extractSubobject(EvalInfo &Info, const Expr *E, + const CompleteObject &Obj, + const SubobjectDesignator &Sub, + APValue &Result) { + ExtractSubobjectHandler Handler = { Info, Result }; + return findSubobject(Info, E, Obj, Sub, Handler); +} + +namespace { +struct ModifySubobjectHandler { + EvalInfo &Info; + APValue &NewVal; + const Expr *E; + + typedef bool result_type; + static const AccessKinds AccessKind = AK_Assign; + + bool checkConst(QualType QT) { + // Assigning to a const object has undefined behavior. + if (QT.isConstQualified()) { + Info.Diag(E, diag::note_constexpr_modify_const_type) << QT; + return false; + } + return true; + } + + bool failed() { return false; } + bool found(APValue &Subobj, QualType SubobjType) { + if (!checkConst(SubobjType)) + return false; + // We've been given ownership of NewVal, so just swap it in. + Subobj.swap(NewVal); + return true; + } + bool found(APSInt &Value, QualType SubobjType) { + if (!checkConst(SubobjType)) + return false; + if (!NewVal.isInt()) { + // Maybe trying to write a cast pointer value into a complex? + Info.Diag(E); + return false; + } + Value = NewVal.getInt(); + return true; + } + bool found(APFloat &Value, QualType SubobjType) { + if (!checkConst(SubobjType)) + return false; + Value = NewVal.getFloat(); + return true; + } + bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { + llvm_unreachable("shouldn't encounter string elements with ExpandArrays"); + } +}; +} // end anonymous namespace + +const AccessKinds ModifySubobjectHandler::AccessKind; + +/// Update the designated sub-object of an rvalue to the given value. +static bool modifySubobject(EvalInfo &Info, const Expr *E, + const CompleteObject &Obj, + const SubobjectDesignator &Sub, + APValue &NewVal) { + ModifySubobjectHandler Handler = { Info, NewVal, E }; + return findSubobject(Info, E, Obj, Sub, Handler); +} + +/// Find the position where two subobject designators diverge, or equivalently +/// the length of the common initial subsequence. +static unsigned FindDesignatorMismatch(QualType ObjType, + const SubobjectDesignator &A, + const SubobjectDesignator &B, + bool &WasArrayIndex) { + unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size()); + for (/**/; I != N; ++I) { + if (!ObjType.isNull() && + (ObjType->isArrayType() || ObjType->isAnyComplexType())) { + // Next subobject is an array element. + if (A.Entries[I].ArrayIndex != B.Entries[I].ArrayIndex) { + WasArrayIndex = true; + return I; + } + if (ObjType->isAnyComplexType()) + ObjType = ObjType->castAs<ComplexType>()->getElementType(); + else + ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType(); + } else { + if (A.Entries[I].BaseOrMember != B.Entries[I].BaseOrMember) { + WasArrayIndex = false; + return I; + } + if (const FieldDecl *FD = getAsField(A.Entries[I])) + // Next subobject is a field. + ObjType = FD->getType(); + else + // Next subobject is a base class. + ObjType = QualType(); + } + } + WasArrayIndex = false; + return I; +} + +/// Determine whether the given subobject designators refer to elements of the +/// same array object. +static bool AreElementsOfSameArray(QualType ObjType, + const SubobjectDesignator &A, + const SubobjectDesignator &B) { + if (A.Entries.size() != B.Entries.size()) + return false; + + bool IsArray = A.MostDerivedArraySize != 0; + if (IsArray && A.MostDerivedPathLength != A.Entries.size()) + // A is a subobject of the array element. + return false; + + // If A (and B) designates an array element, the last entry will be the array + // index. That doesn't have to match. Otherwise, we're in the 'implicit array + // of length 1' case, and the entire path must match. + bool WasArrayIndex; + unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex); + return CommonLength >= A.Entries.size() - IsArray; +} + +/// Find the complete object to which an LValue refers. +static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E, + AccessKinds AK, const LValue &LVal, + QualType LValType) { + if (!LVal.Base) { + Info.Diag(E, diag::note_constexpr_access_null) << AK; + return CompleteObject(); + } + + CallStackFrame *Frame = nullptr; + if (LVal.CallIndex) { + Frame = Info.getCallFrame(LVal.CallIndex); + if (!Frame) { + Info.Diag(E, diag::note_constexpr_lifetime_ended, 1) + << AK << LVal.Base.is<const ValueDecl*>(); + NoteLValueLocation(Info, LVal.Base); + return CompleteObject(); + } + } + + // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type + // is not a constant expression (even if the object is non-volatile). We also + // apply this rule to C++98, in order to conform to the expected 'volatile' + // semantics. + if (LValType.isVolatileQualified()) { + if (Info.getLangOpts().CPlusPlus) + Info.Diag(E, diag::note_constexpr_access_volatile_type) + << AK << LValType; + else + Info.Diag(E); + return CompleteObject(); + } + + // Compute value storage location and type of base object. + APValue *BaseVal = nullptr; + QualType BaseType = getType(LVal.Base); + + if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl*>()) { + // In C++98, const, non-volatile integers initialized with ICEs are ICEs. + // In C++11, constexpr, non-volatile variables initialized with constant + // expressions are constant expressions too. Inside constexpr functions, + // parameters are constant expressions even if they're non-const. + // In C++1y, objects local to a constant expression (those with a Frame) are + // both readable and writable inside constant expressions. + // In C, such things can also be folded, although they are not ICEs. + const VarDecl *VD = dyn_cast<VarDecl>(D); + if (VD) { + if (const VarDecl *VDef = VD->getDefinition(Info.Ctx)) + VD = VDef; + } + if (!VD || VD->isInvalidDecl()) { + Info.Diag(E); + return CompleteObject(); + } + + // Accesses of volatile-qualified objects are not allowed. + if (BaseType.isVolatileQualified()) { + if (Info.getLangOpts().CPlusPlus) { + Info.Diag(E, diag::note_constexpr_access_volatile_obj, 1) + << AK << 1 << VD; + Info.Note(VD->getLocation(), diag::note_declared_at); + } else { + Info.Diag(E); + } + return CompleteObject(); + } + + // Unless we're looking at a local variable or argument in a constexpr call, + // the variable we're reading must be const. + if (!Frame) { + if (Info.getLangOpts().CPlusPlus14 && + VD == Info.EvaluatingDecl.dyn_cast<const ValueDecl *>()) { + // OK, we can read and modify an object if we're in the process of + // evaluating its initializer, because its lifetime began in this + // evaluation. + } else if (AK != AK_Read) { + // All the remaining cases only permit reading. + Info.Diag(E, diag::note_constexpr_modify_global); + return CompleteObject(); + } else if (VD->isConstexpr()) { + // OK, we can read this variable. + } else if (BaseType->isIntegralOrEnumerationType()) { + if (!BaseType.isConstQualified()) { + if (Info.getLangOpts().CPlusPlus) { + Info.Diag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD; + Info.Note(VD->getLocation(), diag::note_declared_at); + } else { + Info.Diag(E); + } + return CompleteObject(); + } + } else if (BaseType->isFloatingType() && BaseType.isConstQualified()) { + // We support folding of const floating-point types, in order to make + // static const data members of such types (supported as an extension) + // more useful. + if (Info.getLangOpts().CPlusPlus11) { + Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; + Info.Note(VD->getLocation(), diag::note_declared_at); + } else { + Info.CCEDiag(E); + } + } else { + // FIXME: Allow folding of values of any literal type in all languages. + if (Info.getLangOpts().CPlusPlus11) { + Info.Diag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; + Info.Note(VD->getLocation(), diag::note_declared_at); + } else { + Info.Diag(E); + } + return CompleteObject(); + } + } + + if (!evaluateVarDeclInit(Info, E, VD, Frame, BaseVal)) + return CompleteObject(); + } else { + const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); + + if (!Frame) { + if (const MaterializeTemporaryExpr *MTE = + dyn_cast<MaterializeTemporaryExpr>(Base)) { + assert(MTE->getStorageDuration() == SD_Static && + "should have a frame for a non-global materialized temporary"); + + // Per C++1y [expr.const]p2: + // an lvalue-to-rvalue conversion [is not allowed unless it applies to] + // - a [...] glvalue of integral or enumeration type that refers to + // a non-volatile const object [...] + // [...] + // - a [...] glvalue of literal type that refers to a non-volatile + // object whose lifetime began within the evaluation of e. + // + // C++11 misses the 'began within the evaluation of e' check and + // instead allows all temporaries, including things like: + // int &&r = 1; + // int x = ++r; + // constexpr int k = r; + // Therefore we use the C++1y rules in C++11 too. + const ValueDecl *VD = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>(); + const ValueDecl *ED = MTE->getExtendingDecl(); + if (!(BaseType.isConstQualified() && + BaseType->isIntegralOrEnumerationType()) && + !(VD && VD->getCanonicalDecl() == ED->getCanonicalDecl())) { + Info.Diag(E, diag::note_constexpr_access_static_temporary, 1) << AK; + Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here); + return CompleteObject(); + } + + BaseVal = Info.Ctx.getMaterializedTemporaryValue(MTE, false); + assert(BaseVal && "got reference to unevaluated temporary"); + } else { + Info.Diag(E); + return CompleteObject(); + } + } else { + BaseVal = Frame->getTemporary(Base); + assert(BaseVal && "missing value for temporary"); + } + + // Volatile temporary objects cannot be accessed in constant expressions. + if (BaseType.isVolatileQualified()) { + if (Info.getLangOpts().CPlusPlus) { + Info.Diag(E, diag::note_constexpr_access_volatile_obj, 1) + << AK << 0; + Info.Note(Base->getExprLoc(), diag::note_constexpr_temporary_here); + } else { + Info.Diag(E); + } + return CompleteObject(); + } + } + + // During the construction of an object, it is not yet 'const'. + // FIXME: We don't set up EvaluatingDecl for local variables or temporaries, + // and this doesn't do quite the right thing for const subobjects of the + // object under construction. + if (LVal.getLValueBase() == Info.EvaluatingDecl) { + BaseType = Info.Ctx.getCanonicalType(BaseType); + BaseType.removeLocalConst(); + } + + // In C++1y, we can't safely access any mutable state when we might be + // evaluating after an unmodeled side effect or an evaluation failure. + // + // FIXME: Not all local state is mutable. Allow local constant subobjects + // to be read here (but take care with 'mutable' fields). + if (Frame && Info.getLangOpts().CPlusPlus14 && + (Info.EvalStatus.HasSideEffects || Info.keepEvaluatingAfterFailure())) + return CompleteObject(); + + return CompleteObject(BaseVal, BaseType); +} + +/// \brief Perform an lvalue-to-rvalue conversion on the given glvalue. This +/// can also be used for 'lvalue-to-lvalue' conversions for looking up the +/// glvalue referred to by an entity of reference type. +/// +/// \param Info - Information about the ongoing evaluation. +/// \param Conv - The expression for which we are performing the conversion. +/// Used for diagnostics. +/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the +/// case of a non-class type). +/// \param LVal - The glvalue on which we are attempting to perform this action. +/// \param RVal - The produced value will be placed here. +static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, + QualType Type, + const LValue &LVal, APValue &RVal) { + if (LVal.Designator.Invalid) + return false; + + // Check for special cases where there is no existing APValue to look at. + const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); + if (!LVal.Designator.Invalid && Base && !LVal.CallIndex && + !Type.isVolatileQualified()) { + if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) { + // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the + // initializer until now for such expressions. Such an expression can't be + // an ICE in C, so this only matters for fold. + assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?"); + if (Type.isVolatileQualified()) { + Info.Diag(Conv); + return false; + } + APValue Lit; + if (!Evaluate(Lit, Info, CLE->getInitializer())) + return false; + CompleteObject LitObj(&Lit, Base->getType()); + return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal); + } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) { + // We represent a string literal array as an lvalue pointing at the + // corresponding expression, rather than building an array of chars. + // FIXME: Support ObjCEncodeExpr, MakeStringConstant + APValue Str(Base, CharUnits::Zero(), APValue::NoLValuePath(), 0); + CompleteObject StrObj(&Str, Base->getType()); + return extractSubobject(Info, Conv, StrObj, LVal.Designator, RVal); + } + } + + CompleteObject Obj = findCompleteObject(Info, Conv, AK_Read, LVal, Type); + return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal); +} + +/// Perform an assignment of Val to LVal. Takes ownership of Val. +static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal, + QualType LValType, APValue &Val) { + if (LVal.Designator.Invalid) + return false; + + if (!Info.getLangOpts().CPlusPlus14) { + Info.Diag(E); + return false; + } + + CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); + return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val); +} + +static bool isOverflowingIntegerType(ASTContext &Ctx, QualType T) { + return T->isSignedIntegerType() && + Ctx.getIntWidth(T) >= Ctx.getIntWidth(Ctx.IntTy); +} + +namespace { +struct CompoundAssignSubobjectHandler { + EvalInfo &Info; + const Expr *E; + QualType PromotedLHSType; + BinaryOperatorKind Opcode; + const APValue &RHS; + + static const AccessKinds AccessKind = AK_Assign; + + typedef bool result_type; + + bool checkConst(QualType QT) { + // Assigning to a const object has undefined behavior. + if (QT.isConstQualified()) { + Info.Diag(E, diag::note_constexpr_modify_const_type) << QT; + return false; + } + return true; + } + + bool failed() { return false; } + bool found(APValue &Subobj, QualType SubobjType) { + switch (Subobj.getKind()) { + case APValue::Int: + return found(Subobj.getInt(), SubobjType); + case APValue::Float: + return found(Subobj.getFloat(), SubobjType); + case APValue::ComplexInt: + case APValue::ComplexFloat: + // FIXME: Implement complex compound assignment. + Info.Diag(E); + return false; + case APValue::LValue: + return foundPointer(Subobj, SubobjType); + default: + // FIXME: can this happen? + Info.Diag(E); + return false; + } + } + bool found(APSInt &Value, QualType SubobjType) { + if (!checkConst(SubobjType)) + return false; + + if (!SubobjType->isIntegerType() || !RHS.isInt()) { + // We don't support compound assignment on integer-cast-to-pointer + // values. + Info.Diag(E); + return false; + } + + APSInt LHS = HandleIntToIntCast(Info, E, PromotedLHSType, + SubobjType, Value); + if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS)) + return false; + Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS); + return true; + } + bool found(APFloat &Value, QualType SubobjType) { + return checkConst(SubobjType) && + HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType, + Value) && + handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) && + HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value); + } + bool foundPointer(APValue &Subobj, QualType SubobjType) { + if (!checkConst(SubobjType)) + return false; + + QualType PointeeType; + if (const PointerType *PT = SubobjType->getAs<PointerType>()) + PointeeType = PT->getPointeeType(); + + if (PointeeType.isNull() || !RHS.isInt() || + (Opcode != BO_Add && Opcode != BO_Sub)) { + Info.Diag(E); + return false; + } + + int64_t Offset = getExtValue(RHS.getInt()); + if (Opcode == BO_Sub) + Offset = -Offset; + + LValue LVal; + LVal.setFrom(Info.Ctx, Subobj); + if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset)) + return false; + LVal.moveInto(Subobj); + return true; + } + bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { + llvm_unreachable("shouldn't encounter string elements here"); + } +}; +} // end anonymous namespace + +const AccessKinds CompoundAssignSubobjectHandler::AccessKind; + +/// Perform a compound assignment of LVal <op>= RVal. +static bool handleCompoundAssignment( + EvalInfo &Info, const Expr *E, + const LValue &LVal, QualType LValType, QualType PromotedLValType, + BinaryOperatorKind Opcode, const APValue &RVal) { + if (LVal.Designator.Invalid) + return false; + + if (!Info.getLangOpts().CPlusPlus14) { + Info.Diag(E); + return false; + } + + CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); + CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode, + RVal }; + return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); +} + +namespace { +struct IncDecSubobjectHandler { + EvalInfo &Info; + const Expr *E; + AccessKinds AccessKind; + APValue *Old; + + typedef bool result_type; + + bool checkConst(QualType QT) { + // Assigning to a const object has undefined behavior. + if (QT.isConstQualified()) { + Info.Diag(E, diag::note_constexpr_modify_const_type) << QT; + return false; + } + return true; + } + + bool failed() { return false; } + bool found(APValue &Subobj, QualType SubobjType) { + // Stash the old value. Also clear Old, so we don't clobber it later + // if we're post-incrementing a complex. + if (Old) { + *Old = Subobj; + Old = nullptr; + } + + switch (Subobj.getKind()) { + case APValue::Int: + return found(Subobj.getInt(), SubobjType); + case APValue::Float: + return found(Subobj.getFloat(), SubobjType); + case APValue::ComplexInt: + return found(Subobj.getComplexIntReal(), + SubobjType->castAs<ComplexType>()->getElementType() + .withCVRQualifiers(SubobjType.getCVRQualifiers())); + case APValue::ComplexFloat: + return found(Subobj.getComplexFloatReal(), + SubobjType->castAs<ComplexType>()->getElementType() + .withCVRQualifiers(SubobjType.getCVRQualifiers())); + case APValue::LValue: + return foundPointer(Subobj, SubobjType); + default: + // FIXME: can this happen? + Info.Diag(E); + return false; + } + } + bool found(APSInt &Value, QualType SubobjType) { + if (!checkConst(SubobjType)) + return false; + + if (!SubobjType->isIntegerType()) { + // We don't support increment / decrement on integer-cast-to-pointer + // values. + Info.Diag(E); + return false; + } + + if (Old) *Old = APValue(Value); + + // bool arithmetic promotes to int, and the conversion back to bool + // doesn't reduce mod 2^n, so special-case it. + if (SubobjType->isBooleanType()) { + if (AccessKind == AK_Increment) + Value = 1; + else + Value = !Value; + return true; + } + + bool WasNegative = Value.isNegative(); + if (AccessKind == AK_Increment) { + ++Value; + + if (!WasNegative && Value.isNegative() && + isOverflowingIntegerType(Info.Ctx, SubobjType)) { + APSInt ActualValue(Value, /*IsUnsigned*/true); + HandleOverflow(Info, E, ActualValue, SubobjType); + } + } else { + --Value; + + if (WasNegative && !Value.isNegative() && + isOverflowingIntegerType(Info.Ctx, SubobjType)) { + unsigned BitWidth = Value.getBitWidth(); + APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false); + ActualValue.setBit(BitWidth); + HandleOverflow(Info, E, ActualValue, SubobjType); + } + } + return true; + } + bool found(APFloat &Value, QualType SubobjType) { + if (!checkConst(SubobjType)) + return false; + + if (Old) *Old = APValue(Value); + + APFloat One(Value.getSemantics(), 1); + if (AccessKind == AK_Increment) + Value.add(One, APFloat::rmNearestTiesToEven); + else + Value.subtract(One, APFloat::rmNearestTiesToEven); + return true; + } + bool foundPointer(APValue &Subobj, QualType SubobjType) { + if (!checkConst(SubobjType)) + return false; + + QualType PointeeType; + if (const PointerType *PT = SubobjType->getAs<PointerType>()) + PointeeType = PT->getPointeeType(); + else { + Info.Diag(E); + return false; + } + + LValue LVal; + LVal.setFrom(Info.Ctx, Subobj); + if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, + AccessKind == AK_Increment ? 1 : -1)) + return false; + LVal.moveInto(Subobj); + return true; + } + bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { + llvm_unreachable("shouldn't encounter string elements here"); + } +}; +} // end anonymous namespace + +/// Perform an increment or decrement on LVal. +static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal, + QualType LValType, bool IsIncrement, APValue *Old) { + if (LVal.Designator.Invalid) + return false; + + if (!Info.getLangOpts().CPlusPlus14) { + Info.Diag(E); + return false; + } + + AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement; + CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType); + IncDecSubobjectHandler Handler = { Info, E, AK, Old }; + return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); +} + +/// Build an lvalue for the object argument of a member function call. +static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object, + LValue &This) { + if (Object->getType()->isPointerType()) + return EvaluatePointer(Object, This, Info); + + if (Object->isGLValue()) + return EvaluateLValue(Object, This, Info); + + if (Object->getType()->isLiteralType(Info.Ctx)) + return EvaluateTemporary(Object, This, Info); + + Info.Diag(Object, diag::note_constexpr_nonliteral) << Object->getType(); + return false; +} + +/// HandleMemberPointerAccess - Evaluate a member access operation and build an +/// lvalue referring to the result. +/// +/// \param Info - Information about the ongoing evaluation. +/// \param LV - An lvalue referring to the base of the member pointer. +/// \param RHS - The member pointer expression. +/// \param IncludeMember - Specifies whether the member itself is included in +/// the resulting LValue subobject designator. This is not possible when +/// creating a bound member function. +/// \return The field or method declaration to which the member pointer refers, +/// or 0 if evaluation fails. +static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, + QualType LVType, + LValue &LV, + const Expr *RHS, + bool IncludeMember = true) { + MemberPtr MemPtr; + if (!EvaluateMemberPointer(RHS, MemPtr, Info)) + return nullptr; + + // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to + // member value, the behavior is undefined. + if (!MemPtr.getDecl()) { + // FIXME: Specific diagnostic. + Info.Diag(RHS); + return nullptr; + } + + if (MemPtr.isDerivedMember()) { + // This is a member of some derived class. Truncate LV appropriately. + // The end of the derived-to-base path for the base object must match the + // derived-to-base path for the member pointer. + if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() > + LV.Designator.Entries.size()) { + Info.Diag(RHS); + return nullptr; + } + unsigned PathLengthToMember = + LV.Designator.Entries.size() - MemPtr.Path.size(); + for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) { + const CXXRecordDecl *LVDecl = getAsBaseClass( + LV.Designator.Entries[PathLengthToMember + I]); + const CXXRecordDecl *MPDecl = MemPtr.Path[I]; + if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) { + Info.Diag(RHS); + return nullptr; + } + } + + // Truncate the lvalue to the appropriate derived class. + if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(), + PathLengthToMember)) + return nullptr; + } else if (!MemPtr.Path.empty()) { + // Extend the LValue path with the member pointer's path. + LV.Designator.Entries.reserve(LV.Designator.Entries.size() + + MemPtr.Path.size() + IncludeMember); + + // Walk down to the appropriate base class. + if (const PointerType *PT = LVType->getAs<PointerType>()) + LVType = PT->getPointeeType(); + const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl(); + assert(RD && "member pointer access on non-class-type expression"); + // The first class in the path is that of the lvalue. + for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) { + const CXXRecordDecl *Base = MemPtr.Path[N - I - 1]; + if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base)) + return nullptr; + RD = Base; + } + // Finally cast to the class containing the member. + if (!HandleLValueDirectBase(Info, RHS, LV, RD, + MemPtr.getContainingRecord())) + return nullptr; + } + + // Add the member. Note that we cannot build bound member functions here. + if (IncludeMember) { + if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) { + if (!HandleLValueMember(Info, RHS, LV, FD)) + return nullptr; + } else if (const IndirectFieldDecl *IFD = + dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) { + if (!HandleLValueIndirectMember(Info, RHS, LV, IFD)) + return nullptr; + } else { + llvm_unreachable("can't construct reference to bound member function"); + } + } + + return MemPtr.getDecl(); +} + +static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, + const BinaryOperator *BO, + LValue &LV, + bool IncludeMember = true) { + assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI); + + if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) { + if (Info.keepEvaluatingAfterFailure()) { + MemberPtr MemPtr; + EvaluateMemberPointer(BO->getRHS(), MemPtr, Info); + } + return nullptr; + } + + return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV, + BO->getRHS(), IncludeMember); +} + +/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on +/// the provided lvalue, which currently refers to the base object. +static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E, + LValue &Result) { + SubobjectDesignator &D = Result.Designator; + if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived)) + return false; + + QualType TargetQT = E->getType(); + if (const PointerType *PT = TargetQT->getAs<PointerType>()) + TargetQT = PT->getPointeeType(); + + // Check this cast lands within the final derived-to-base subobject path. + if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) { + Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) + << D.MostDerivedType << TargetQT; + return false; + } + + // Check the type of the final cast. We don't need to check the path, + // since a cast can only be formed if the path is unique. + unsigned NewEntriesSize = D.Entries.size() - E->path_size(); + const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl(); + const CXXRecordDecl *FinalType; + if (NewEntriesSize == D.MostDerivedPathLength) + FinalType = D.MostDerivedType->getAsCXXRecordDecl(); + else + FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]); + if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) { + Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) + << D.MostDerivedType << TargetQT; + return false; + } + + // Truncate the lvalue to the appropriate derived class. + return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize); +} + +namespace { +enum EvalStmtResult { + /// Evaluation failed. + ESR_Failed, + /// Hit a 'return' statement. + ESR_Returned, + /// Evaluation succeeded. + ESR_Succeeded, + /// Hit a 'continue' statement. + ESR_Continue, + /// Hit a 'break' statement. + ESR_Break, + /// Still scanning for 'case' or 'default' statement. + ESR_CaseNotFound +}; +} + +static bool EvaluateDecl(EvalInfo &Info, const Decl *D) { + if (const VarDecl *VD = dyn_cast<VarDecl>(D)) { + // We don't need to evaluate the initializer for a static local. + if (!VD->hasLocalStorage()) + return true; + + LValue Result; + Result.set(VD, Info.CurrentCall->Index); + APValue &Val = Info.CurrentCall->createTemporary(VD, true); + + const Expr *InitE = VD->getInit(); + if (!InitE) { + Info.Diag(D->getLocStart(), diag::note_constexpr_uninitialized) + << false << VD->getType(); + Val = APValue(); + return false; + } + + if (InitE->isValueDependent()) + return false; + + if (!EvaluateInPlace(Val, Info, Result, InitE)) { + // Wipe out any partially-computed value, to allow tracking that this + // evaluation failed. + Val = APValue(); + return false; + } + } + + return true; +} + +/// Evaluate a condition (either a variable declaration or an expression). +static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl, + const Expr *Cond, bool &Result) { + FullExpressionRAII Scope(Info); + if (CondDecl && !EvaluateDecl(Info, CondDecl)) + return false; + return EvaluateAsBooleanCondition(Cond, Result, Info); +} + +static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info, + const Stmt *S, + const SwitchCase *SC = nullptr); + +/// Evaluate the body of a loop, and translate the result as appropriate. +static EvalStmtResult EvaluateLoopBody(APValue &Result, EvalInfo &Info, + const Stmt *Body, + const SwitchCase *Case = nullptr) { + BlockScopeRAII Scope(Info); + switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case)) { + case ESR_Break: + return ESR_Succeeded; + case ESR_Succeeded: + case ESR_Continue: + return ESR_Continue; + case ESR_Failed: + case ESR_Returned: + case ESR_CaseNotFound: + return ESR; + } + llvm_unreachable("Invalid EvalStmtResult!"); +} + +/// Evaluate a switch statement. +static EvalStmtResult EvaluateSwitch(APValue &Result, EvalInfo &Info, + const SwitchStmt *SS) { + BlockScopeRAII Scope(Info); + + // Evaluate the switch condition. + APSInt Value; + { + FullExpressionRAII Scope(Info); + if (SS->getConditionVariable() && + !EvaluateDecl(Info, SS->getConditionVariable())) + return ESR_Failed; + if (!EvaluateInteger(SS->getCond(), Value, Info)) + return ESR_Failed; + } + + // Find the switch case corresponding to the value of the condition. + // FIXME: Cache this lookup. + const SwitchCase *Found = nullptr; + for (const SwitchCase *SC = SS->getSwitchCaseList(); SC; + SC = SC->getNextSwitchCase()) { + if (isa<DefaultStmt>(SC)) { + Found = SC; + continue; + } + + const CaseStmt *CS = cast<CaseStmt>(SC); + APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx); + APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx) + : LHS; + if (LHS <= Value && Value <= RHS) { + Found = SC; + break; + } + } + + if (!Found) + return ESR_Succeeded; + + // Search the switch body for the switch case and evaluate it from there. + switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found)) { + case ESR_Break: + return ESR_Succeeded; + case ESR_Succeeded: + case ESR_Continue: + case ESR_Failed: + case ESR_Returned: + return ESR; + case ESR_CaseNotFound: + // This can only happen if the switch case is nested within a statement + // expression. We have no intention of supporting that. + Info.Diag(Found->getLocStart(), diag::note_constexpr_stmt_expr_unsupported); + return ESR_Failed; + } + llvm_unreachable("Invalid EvalStmtResult!"); +} + +// Evaluate a statement. +static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info, + const Stmt *S, const SwitchCase *Case) { + if (!Info.nextStep(S)) + return ESR_Failed; + + // If we're hunting down a 'case' or 'default' label, recurse through + // substatements until we hit the label. + if (Case) { + // FIXME: We don't start the lifetime of objects whose initialization we + // jump over. However, such objects must be of class type with a trivial + // default constructor that initialize all subobjects, so must be empty, + // so this almost never matters. + switch (S->getStmtClass()) { + case Stmt::CompoundStmtClass: + // FIXME: Precompute which substatement of a compound statement we + // would jump to, and go straight there rather than performing a + // linear scan each time. + case Stmt::LabelStmtClass: + case Stmt::AttributedStmtClass: + case Stmt::DoStmtClass: + break; + + case Stmt::CaseStmtClass: + case Stmt::DefaultStmtClass: + if (Case == S) + Case = nullptr; + break; + + case Stmt::IfStmtClass: { + // FIXME: Precompute which side of an 'if' we would jump to, and go + // straight there rather than scanning both sides. + const IfStmt *IS = cast<IfStmt>(S); + + // Wrap the evaluation in a block scope, in case it's a DeclStmt + // preceded by our switch label. + BlockScopeRAII Scope(Info); + + EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case); + if (ESR != ESR_CaseNotFound || !IS->getElse()) + return ESR; + return EvaluateStmt(Result, Info, IS->getElse(), Case); + } + + case Stmt::WhileStmtClass: { + EvalStmtResult ESR = + EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case); + if (ESR != ESR_Continue) + return ESR; + break; + } + + case Stmt::ForStmtClass: { + const ForStmt *FS = cast<ForStmt>(S); + EvalStmtResult ESR = + EvaluateLoopBody(Result, Info, FS->getBody(), Case); + if (ESR != ESR_Continue) + return ESR; + if (FS->getInc()) { + FullExpressionRAII IncScope(Info); + if (!EvaluateIgnoredValue(Info, FS->getInc())) + return ESR_Failed; + } + break; + } + + case Stmt::DeclStmtClass: + // FIXME: If the variable has initialization that can't be jumped over, + // bail out of any immediately-surrounding compound-statement too. + default: + return ESR_CaseNotFound; + } + } + + switch (S->getStmtClass()) { + default: + if (const Expr *E = dyn_cast<Expr>(S)) { + // Don't bother evaluating beyond an expression-statement which couldn't + // be evaluated. + FullExpressionRAII Scope(Info); + if (!EvaluateIgnoredValue(Info, E)) + return ESR_Failed; + return ESR_Succeeded; + } + + Info.Diag(S->getLocStart()); + return ESR_Failed; + + case Stmt::NullStmtClass: + return ESR_Succeeded; + + case Stmt::DeclStmtClass: { + const DeclStmt *DS = cast<DeclStmt>(S); + for (const auto *DclIt : DS->decls()) { + // Each declaration initialization is its own full-expression. + // FIXME: This isn't quite right; if we're performing aggregate + // initialization, each braced subexpression is its own full-expression. + FullExpressionRAII Scope(Info); + if (!EvaluateDecl(Info, DclIt) && !Info.keepEvaluatingAfterFailure()) + return ESR_Failed; + } + return ESR_Succeeded; + } + + case Stmt::ReturnStmtClass: { + const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue(); + FullExpressionRAII Scope(Info); + if (RetExpr && !Evaluate(Result, Info, RetExpr)) + return ESR_Failed; + return ESR_Returned; + } + + case Stmt::CompoundStmtClass: { + BlockScopeRAII Scope(Info); + + const CompoundStmt *CS = cast<CompoundStmt>(S); + for (const auto *BI : CS->body()) { + EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case); + if (ESR == ESR_Succeeded) + Case = nullptr; + else if (ESR != ESR_CaseNotFound) + return ESR; + } + return Case ? ESR_CaseNotFound : ESR_Succeeded; + } + + case Stmt::IfStmtClass: { + const IfStmt *IS = cast<IfStmt>(S); + + // Evaluate the condition, as either a var decl or as an expression. + BlockScopeRAII Scope(Info); + bool Cond; + if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond)) + return ESR_Failed; + + if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) { + EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt); + if (ESR != ESR_Succeeded) + return ESR; + } + return ESR_Succeeded; + } + + case Stmt::WhileStmtClass: { + const WhileStmt *WS = cast<WhileStmt>(S); + while (true) { + BlockScopeRAII Scope(Info); + bool Continue; + if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(), + Continue)) + return ESR_Failed; + if (!Continue) + break; + + EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody()); + if (ESR != ESR_Continue) + return ESR; + } + return ESR_Succeeded; + } + + case Stmt::DoStmtClass: { + const DoStmt *DS = cast<DoStmt>(S); + bool Continue; + do { + EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case); + if (ESR != ESR_Continue) + return ESR; + Case = nullptr; + + FullExpressionRAII CondScope(Info); + if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info)) + return ESR_Failed; + } while (Continue); + return ESR_Succeeded; + } + + case Stmt::ForStmtClass: { + const ForStmt *FS = cast<ForStmt>(S); + BlockScopeRAII Scope(Info); + if (FS->getInit()) { + EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); + if (ESR != ESR_Succeeded) + return ESR; + } + while (true) { + BlockScopeRAII Scope(Info); + bool Continue = true; + if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(), + FS->getCond(), Continue)) + return ESR_Failed; + if (!Continue) + break; + + EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody()); + if (ESR != ESR_Continue) + return ESR; + + if (FS->getInc()) { + FullExpressionRAII IncScope(Info); + if (!EvaluateIgnoredValue(Info, FS->getInc())) + return ESR_Failed; + } + } + return ESR_Succeeded; + } + + case Stmt::CXXForRangeStmtClass: { + const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S); + BlockScopeRAII Scope(Info); + + // Initialize the __range variable. + EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt()); + if (ESR != ESR_Succeeded) + return ESR; + + // Create the __begin and __end iterators. + ESR = EvaluateStmt(Result, Info, FS->getBeginEndStmt()); + if (ESR != ESR_Succeeded) + return ESR; + + while (true) { + // Condition: __begin != __end. + { + bool Continue = true; + FullExpressionRAII CondExpr(Info); + if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info)) + return ESR_Failed; + if (!Continue) + break; + } + + // User's variable declaration, initialized by *__begin. + BlockScopeRAII InnerScope(Info); + ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt()); + if (ESR != ESR_Succeeded) + return ESR; + + // Loop body. + ESR = EvaluateLoopBody(Result, Info, FS->getBody()); + if (ESR != ESR_Continue) + return ESR; + + // Increment: ++__begin + if (!EvaluateIgnoredValue(Info, FS->getInc())) + return ESR_Failed; + } + + return ESR_Succeeded; + } + + case Stmt::SwitchStmtClass: + return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S)); + + case Stmt::ContinueStmtClass: + return ESR_Continue; + + case Stmt::BreakStmtClass: + return ESR_Break; + + case Stmt::LabelStmtClass: + return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case); + + case Stmt::AttributedStmtClass: + // As a general principle, C++11 attributes can be ignored without + // any semantic impact. + return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(), + Case); + + case Stmt::CaseStmtClass: + case Stmt::DefaultStmtClass: + return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case); + } +} + +/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial +/// default constructor. If so, we'll fold it whether or not it's marked as +/// constexpr. If it is marked as constexpr, we will never implicitly define it, +/// so we need special handling. +static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc, + const CXXConstructorDecl *CD, + bool IsValueInitialization) { + if (!CD->isTrivial() || !CD->isDefaultConstructor()) + return false; + + // Value-initialization does not call a trivial default constructor, so such a + // call is a core constant expression whether or not the constructor is + // constexpr. + if (!CD->isConstexpr() && !IsValueInitialization) { + if (Info.getLangOpts().CPlusPlus11) { + // FIXME: If DiagDecl is an implicitly-declared special member function, + // we should be much more explicit about why it's not constexpr. + Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1) + << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD; + Info.Note(CD->getLocation(), diag::note_declared_at); + } else { + Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr); + } + } + return true; +} + +/// CheckConstexprFunction - Check that a function can be called in a constant +/// expression. +static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc, + const FunctionDecl *Declaration, + const FunctionDecl *Definition) { + // Potential constant expressions can contain calls to declared, but not yet + // defined, constexpr functions. + if (Info.checkingPotentialConstantExpression() && !Definition && + Declaration->isConstexpr()) + return false; + + // Bail out with no diagnostic if the function declaration itself is invalid. + // We will have produced a relevant diagnostic while parsing it. + if (Declaration->isInvalidDecl()) + return false; + + // Can we evaluate this function call? + if (Definition && Definition->isConstexpr() && !Definition->isInvalidDecl()) + return true; + + if (Info.getLangOpts().CPlusPlus11) { + const FunctionDecl *DiagDecl = Definition ? Definition : Declaration; + // FIXME: If DiagDecl is an implicitly-declared special member function, we + // should be much more explicit about why it's not constexpr. + Info.Diag(CallLoc, diag::note_constexpr_invalid_function, 1) + << DiagDecl->isConstexpr() << isa<CXXConstructorDecl>(DiagDecl) + << DiagDecl; + Info.Note(DiagDecl->getLocation(), diag::note_declared_at); + } else { + Info.Diag(CallLoc, diag::note_invalid_subexpr_in_const_expr); + } + return false; +} + +/// Determine if a class has any fields that might need to be copied by a +/// trivial copy or move operation. +static bool hasFields(const CXXRecordDecl *RD) { + if (!RD || RD->isEmpty()) + return false; + for (auto *FD : RD->fields()) { + if (FD->isUnnamedBitfield()) + continue; + return true; + } + for (auto &Base : RD->bases()) + if (hasFields(Base.getType()->getAsCXXRecordDecl())) + return true; + return false; +} + +namespace { +typedef SmallVector<APValue, 8> ArgVector; +} + +/// EvaluateArgs - Evaluate the arguments to a function call. +static bool EvaluateArgs(ArrayRef<const Expr*> Args, ArgVector &ArgValues, + EvalInfo &Info) { + bool Success = true; + for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end(); + I != E; ++I) { + if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) { + // If we're checking for a potential constant expression, evaluate all + // initializers even if some of them fail. + if (!Info.keepEvaluatingAfterFailure()) + return false; + Success = false; + } + } + return Success; +} + +/// Evaluate a function call. +static bool HandleFunctionCall(SourceLocation CallLoc, + const FunctionDecl *Callee, const LValue *This, + ArrayRef<const Expr*> Args, const Stmt *Body, + EvalInfo &Info, APValue &Result) { + ArgVector ArgValues(Args.size()); + if (!EvaluateArgs(Args, ArgValues, Info)) + return false; + + if (!Info.CheckCallLimit(CallLoc)) + return false; + + CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data()); + + // For a trivial copy or move assignment, perform an APValue copy. This is + // essential for unions, where the operations performed by the assignment + // operator cannot be represented as statements. + // + // Skip this for non-union classes with no fields; in that case, the defaulted + // copy/move does not actually read the object. + const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee); + if (MD && MD->isDefaulted() && + (MD->getParent()->isUnion() || + (MD->isTrivial() && hasFields(MD->getParent())))) { + assert(This && + (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())); + LValue RHS; + RHS.setFrom(Info.Ctx, ArgValues[0]); + APValue RHSValue; + if (!handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), + RHS, RHSValue)) + return false; + if (!handleAssignment(Info, Args[0], *This, MD->getThisType(Info.Ctx), + RHSValue)) + return false; + This->moveInto(Result); + return true; + } + + EvalStmtResult ESR = EvaluateStmt(Result, Info, Body); + if (ESR == ESR_Succeeded) { + if (Callee->getReturnType()->isVoidType()) + return true; + Info.Diag(Callee->getLocEnd(), diag::note_constexpr_no_return); + } + return ESR == ESR_Returned; +} + +/// Evaluate a constructor call. +static bool HandleConstructorCall(SourceLocation CallLoc, const LValue &This, + ArrayRef<const Expr*> Args, + const CXXConstructorDecl *Definition, + EvalInfo &Info, APValue &Result) { + ArgVector ArgValues(Args.size()); + if (!EvaluateArgs(Args, ArgValues, Info)) + return false; + + if (!Info.CheckCallLimit(CallLoc)) + return false; + + const CXXRecordDecl *RD = Definition->getParent(); + if (RD->getNumVBases()) { + Info.Diag(CallLoc, diag::note_constexpr_virtual_base) << RD; + return false; + } + + CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues.data()); + + // If it's a delegating constructor, just delegate. + if (Definition->isDelegatingConstructor()) { + CXXConstructorDecl::init_const_iterator I = Definition->init_begin(); + { + FullExpressionRAII InitScope(Info); + if (!EvaluateInPlace(Result, Info, This, (*I)->getInit())) + return false; + } + return EvaluateStmt(Result, Info, Definition->getBody()) != ESR_Failed; + } + + // For a trivial copy or move constructor, perform an APValue copy. This is + // essential for unions (or classes with anonymous union members), where the + // operations performed by the constructor cannot be represented by + // ctor-initializers. + // + // Skip this for empty non-union classes; we should not perform an + // lvalue-to-rvalue conversion on them because their copy constructor does not + // actually read them. + if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() && + (Definition->getParent()->isUnion() || + (Definition->isTrivial() && hasFields(Definition->getParent())))) { + LValue RHS; + RHS.setFrom(Info.Ctx, ArgValues[0]); + return handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), + RHS, Result); + } + + // Reserve space for the struct members. + if (!RD->isUnion() && Result.isUninit()) + Result = APValue(APValue::UninitStruct(), RD->getNumBases(), + std::distance(RD->field_begin(), RD->field_end())); + + if (RD->isInvalidDecl()) return false; + const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); + + // A scope for temporaries lifetime-extended by reference members. + BlockScopeRAII LifetimeExtendedScope(Info); + + bool Success = true; + unsigned BasesSeen = 0; +#ifndef NDEBUG + CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin(); +#endif + for (const auto *I : Definition->inits()) { + LValue Subobject = This; + APValue *Value = &Result; + + // Determine the subobject to initialize. + FieldDecl *FD = nullptr; + if (I->isBaseInitializer()) { + QualType BaseType(I->getBaseClass(), 0); +#ifndef NDEBUG + // Non-virtual base classes are initialized in the order in the class + // definition. We have already checked for virtual base classes. + assert(!BaseIt->isVirtual() && "virtual base for literal type"); + assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && + "base class initializers not in expected order"); + ++BaseIt; +#endif + if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD, + BaseType->getAsCXXRecordDecl(), &Layout)) + return false; + Value = &Result.getStructBase(BasesSeen++); + } else if ((FD = I->getMember())) { + if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout)) + return false; + if (RD->isUnion()) { + Result = APValue(FD); + Value = &Result.getUnionValue(); + } else { + Value = &Result.getStructField(FD->getFieldIndex()); + } + } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) { + // Walk the indirect field decl's chain to find the object to initialize, + // and make sure we've initialized every step along it. + for (auto *C : IFD->chain()) { + FD = cast<FieldDecl>(C); + CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent()); + // Switch the union field if it differs. This happens if we had + // preceding zero-initialization, and we're now initializing a union + // subobject other than the first. + // FIXME: In this case, the values of the other subobjects are + // specified, since zero-initialization sets all padding bits to zero. + if (Value->isUninit() || + (Value->isUnion() && Value->getUnionField() != FD)) { + if (CD->isUnion()) + *Value = APValue(FD); + else + *Value = APValue(APValue::UninitStruct(), CD->getNumBases(), + std::distance(CD->field_begin(), CD->field_end())); + } + if (!HandleLValueMember(Info, I->getInit(), Subobject, FD)) + return false; + if (CD->isUnion()) + Value = &Value->getUnionValue(); + else + Value = &Value->getStructField(FD->getFieldIndex()); + } + } else { + llvm_unreachable("unknown base initializer kind"); + } + + FullExpressionRAII InitScope(Info); + if (!EvaluateInPlace(*Value, Info, Subobject, I->getInit()) || + (FD && FD->isBitField() && !truncateBitfieldValue(Info, I->getInit(), + *Value, FD))) { + // If we're checking for a potential constant expression, evaluate all + // initializers even if some of them fail. + if (!Info.keepEvaluatingAfterFailure()) + return false; + Success = false; + } + } + + return Success && + EvaluateStmt(Result, Info, Definition->getBody()) != ESR_Failed; +} + +//===----------------------------------------------------------------------===// +// Generic Evaluation +//===----------------------------------------------------------------------===// +namespace { + +template <class Derived> +class ExprEvaluatorBase + : public ConstStmtVisitor<Derived, bool> { +private: + bool DerivedSuccess(const APValue &V, const Expr *E) { + return static_cast<Derived*>(this)->Success(V, E); + } + bool DerivedZeroInitialization(const Expr *E) { + return static_cast<Derived*>(this)->ZeroInitialization(E); + } + + // Check whether a conditional operator with a non-constant condition is a + // potential constant expression. If neither arm is a potential constant + // expression, then the conditional operator is not either. + template<typename ConditionalOperator> + void CheckPotentialConstantConditional(const ConditionalOperator *E) { + assert(Info.checkingPotentialConstantExpression()); + + // Speculatively evaluate both arms. + { + SmallVector<PartialDiagnosticAt, 8> Diag; + SpeculativeEvaluationRAII Speculate(Info, &Diag); + + StmtVisitorTy::Visit(E->getFalseExpr()); + if (Diag.empty()) + return; + + Diag.clear(); + StmtVisitorTy::Visit(E->getTrueExpr()); + if (Diag.empty()) + return; + } + + Error(E, diag::note_constexpr_conditional_never_const); + } + + + template<typename ConditionalOperator> + bool HandleConditionalOperator(const ConditionalOperator *E) { + bool BoolResult; + if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) { + if (Info.checkingPotentialConstantExpression()) + CheckPotentialConstantConditional(E); + return false; + } + + Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr(); + return StmtVisitorTy::Visit(EvalExpr); + } + +protected: + EvalInfo &Info; + typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy; + typedef ExprEvaluatorBase ExprEvaluatorBaseTy; + + OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { + return Info.CCEDiag(E, D); + } + + bool ZeroInitialization(const Expr *E) { return Error(E); } + +public: + ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {} + + EvalInfo &getEvalInfo() { return Info; } + + /// Report an evaluation error. This should only be called when an error is + /// first discovered. When propagating an error, just return false. + bool Error(const Expr *E, diag::kind D) { + Info.Diag(E, D); + return false; + } + bool Error(const Expr *E) { + return Error(E, diag::note_invalid_subexpr_in_const_expr); + } + + bool VisitStmt(const Stmt *) { + llvm_unreachable("Expression evaluator should not be called on stmts"); + } + bool VisitExpr(const Expr *E) { + return Error(E); + } + + bool VisitParenExpr(const ParenExpr *E) + { return StmtVisitorTy::Visit(E->getSubExpr()); } + bool VisitUnaryExtension(const UnaryOperator *E) + { return StmtVisitorTy::Visit(E->getSubExpr()); } + bool VisitUnaryPlus(const UnaryOperator *E) + { return StmtVisitorTy::Visit(E->getSubExpr()); } + bool VisitChooseExpr(const ChooseExpr *E) + { return StmtVisitorTy::Visit(E->getChosenSubExpr()); } + bool VisitGenericSelectionExpr(const GenericSelectionExpr *E) + { return StmtVisitorTy::Visit(E->getResultExpr()); } + bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E) + { return StmtVisitorTy::Visit(E->getReplacement()); } + bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) + { return StmtVisitorTy::Visit(E->getExpr()); } + bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) { + // The initializer may not have been parsed yet, or might be erroneous. + if (!E->getExpr()) + return Error(E); + return StmtVisitorTy::Visit(E->getExpr()); + } + // We cannot create any objects for which cleanups are required, so there is + // nothing to do here; all cleanups must come from unevaluated subexpressions. + bool VisitExprWithCleanups(const ExprWithCleanups *E) + { return StmtVisitorTy::Visit(E->getSubExpr()); } + + bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) { + CCEDiag(E, diag::note_constexpr_invalid_cast) << 0; + return static_cast<Derived*>(this)->VisitCastExpr(E); + } + bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) { + CCEDiag(E, diag::note_constexpr_invalid_cast) << 1; + return static_cast<Derived*>(this)->VisitCastExpr(E); + } + + bool VisitBinaryOperator(const BinaryOperator *E) { + switch (E->getOpcode()) { + default: + return Error(E); + + case BO_Comma: + VisitIgnoredValue(E->getLHS()); + return StmtVisitorTy::Visit(E->getRHS()); + + case BO_PtrMemD: + case BO_PtrMemI: { + LValue Obj; + if (!HandleMemberPointerAccess(Info, E, Obj)) + return false; + APValue Result; + if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result)) + return false; + return DerivedSuccess(Result, E); + } + } + } + + bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) { + // Evaluate and cache the common expression. We treat it as a temporary, + // even though it's not quite the same thing. + if (!Evaluate(Info.CurrentCall->createTemporary(E->getOpaqueValue(), false), + Info, E->getCommon())) + return false; + + return HandleConditionalOperator(E); + } + + bool VisitConditionalOperator(const ConditionalOperator *E) { + bool IsBcpCall = false; + // If the condition (ignoring parens) is a __builtin_constant_p call, + // the result is a constant expression if it can be folded without + // side-effects. This is an important GNU extension. See GCC PR38377 + // for discussion. + if (const CallExpr *CallCE = + dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts())) + if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) + IsBcpCall = true; + + // Always assume __builtin_constant_p(...) ? ... : ... is a potential + // constant expression; we can't check whether it's potentially foldable. + if (Info.checkingPotentialConstantExpression() && IsBcpCall) + return false; + + FoldConstant Fold(Info, IsBcpCall); + if (!HandleConditionalOperator(E)) { + Fold.keepDiagnostics(); + return false; + } + + return true; + } + + bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) { + if (APValue *Value = Info.CurrentCall->getTemporary(E)) + return DerivedSuccess(*Value, E); + + const Expr *Source = E->getSourceExpr(); + if (!Source) + return Error(E); + if (Source == E) { // sanity checking. + assert(0 && "OpaqueValueExpr recursively refers to itself"); + return Error(E); + } + return StmtVisitorTy::Visit(Source); + } + + bool VisitCallExpr(const CallExpr *E) { + const Expr *Callee = E->getCallee()->IgnoreParens(); + QualType CalleeType = Callee->getType(); + + const FunctionDecl *FD = nullptr; + LValue *This = nullptr, ThisVal; + auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs()); + bool HasQualifier = false; + + // Extract function decl and 'this' pointer from the callee. + if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) { + const ValueDecl *Member = nullptr; + if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) { + // Explicit bound member calls, such as x.f() or p->g(); + if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal)) + return false; + Member = ME->getMemberDecl(); + This = &ThisVal; + HasQualifier = ME->hasQualifier(); + } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) { + // Indirect bound member calls ('.*' or '->*'). + Member = HandleMemberPointerAccess(Info, BE, ThisVal, false); + if (!Member) return false; + This = &ThisVal; + } else + return Error(Callee); + + FD = dyn_cast<FunctionDecl>(Member); + if (!FD) + return Error(Callee); + } else if (CalleeType->isFunctionPointerType()) { + LValue Call; + if (!EvaluatePointer(Callee, Call, Info)) + return false; + + if (!Call.getLValueOffset().isZero()) + return Error(Callee); + FD = dyn_cast_or_null<FunctionDecl>( + Call.getLValueBase().dyn_cast<const ValueDecl*>()); + if (!FD) + return Error(Callee); + + // Overloaded operator calls to member functions are represented as normal + // calls with '*this' as the first argument. + const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); + if (MD && !MD->isStatic()) { + // FIXME: When selecting an implicit conversion for an overloaded + // operator delete, we sometimes try to evaluate calls to conversion + // operators without a 'this' parameter! + if (Args.empty()) + return Error(E); + + if (!EvaluateObjectArgument(Info, Args[0], ThisVal)) + return false; + This = &ThisVal; + Args = Args.slice(1); + } + + // Don't call function pointers which have been cast to some other type. + if (!Info.Ctx.hasSameType(CalleeType->getPointeeType(), FD->getType())) + return Error(E); + } else + return Error(E); + + if (This && !This->checkSubobject(Info, E, CSK_This)) + return false; + + // DR1358 allows virtual constexpr functions in some cases. Don't allow + // calls to such functions in constant expressions. + if (This && !HasQualifier && + isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isVirtual()) + return Error(E, diag::note_constexpr_virtual_call); + + const FunctionDecl *Definition = nullptr; + Stmt *Body = FD->getBody(Definition); + APValue Result; + + if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition) || + !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, + Info, Result)) + return false; + + return DerivedSuccess(Result, E); + } + + bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { + return StmtVisitorTy::Visit(E->getInitializer()); + } + bool VisitInitListExpr(const InitListExpr *E) { + if (E->getNumInits() == 0) + return DerivedZeroInitialization(E); + if (E->getNumInits() == 1) + return StmtVisitorTy::Visit(E->getInit(0)); + return Error(E); + } + bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) { + return DerivedZeroInitialization(E); + } + bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) { + return DerivedZeroInitialization(E); + } + bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) { + return DerivedZeroInitialization(E); + } + + /// A member expression where the object is a prvalue is itself a prvalue. + bool VisitMemberExpr(const MemberExpr *E) { + assert(!E->isArrow() && "missing call to bound member function?"); + + APValue Val; + if (!Evaluate(Val, Info, E->getBase())) + return false; + + QualType BaseTy = E->getBase()->getType(); + + const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl()); + if (!FD) return Error(E); + assert(!FD->getType()->isReferenceType() && "prvalue reference?"); + assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == + FD->getParent()->getCanonicalDecl() && "record / field mismatch"); + + CompleteObject Obj(&Val, BaseTy); + SubobjectDesignator Designator(BaseTy); + Designator.addDeclUnchecked(FD); + + APValue Result; + return extractSubobject(Info, E, Obj, Designator, Result) && + DerivedSuccess(Result, E); + } + + bool VisitCastExpr(const CastExpr *E) { + switch (E->getCastKind()) { + default: + break; + + case CK_AtomicToNonAtomic: { + APValue AtomicVal; + if (!EvaluateAtomic(E->getSubExpr(), AtomicVal, Info)) + return false; + return DerivedSuccess(AtomicVal, E); + } + + case CK_NoOp: + case CK_UserDefinedConversion: + return StmtVisitorTy::Visit(E->getSubExpr()); + + case CK_LValueToRValue: { + LValue LVal; + if (!EvaluateLValue(E->getSubExpr(), LVal, Info)) + return false; + APValue RVal; + // Note, we use the subexpression's type in order to retain cv-qualifiers. + if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(), + LVal, RVal)) + return false; + return DerivedSuccess(RVal, E); + } + } + + return Error(E); + } + + bool VisitUnaryPostInc(const UnaryOperator *UO) { + return VisitUnaryPostIncDec(UO); + } + bool VisitUnaryPostDec(const UnaryOperator *UO) { + return VisitUnaryPostIncDec(UO); + } + bool VisitUnaryPostIncDec(const UnaryOperator *UO) { + if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) + return Error(UO); + + LValue LVal; + if (!EvaluateLValue(UO->getSubExpr(), LVal, Info)) + return false; + APValue RVal; + if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(), + UO->isIncrementOp(), &RVal)) + return false; + return DerivedSuccess(RVal, UO); + } + + bool VisitStmtExpr(const StmtExpr *E) { + // We will have checked the full-expressions inside the statement expression + // when they were completed, and don't need to check them again now. + if (Info.checkingForOverflow()) + return Error(E); + + BlockScopeRAII Scope(Info); + const CompoundStmt *CS = E->getSubStmt(); + for (CompoundStmt::const_body_iterator BI = CS->body_begin(), + BE = CS->body_end(); + /**/; ++BI) { + if (BI + 1 == BE) { + const Expr *FinalExpr = dyn_cast<Expr>(*BI); + if (!FinalExpr) { + Info.Diag((*BI)->getLocStart(), + diag::note_constexpr_stmt_expr_unsupported); + return false; + } + return this->Visit(FinalExpr); + } + + APValue ReturnValue; + EvalStmtResult ESR = EvaluateStmt(ReturnValue, Info, *BI); + if (ESR != ESR_Succeeded) { + // FIXME: If the statement-expression terminated due to 'return', + // 'break', or 'continue', it would be nice to propagate that to + // the outer statement evaluation rather than bailing out. + if (ESR != ESR_Failed) + Info.Diag((*BI)->getLocStart(), + diag::note_constexpr_stmt_expr_unsupported); + return false; + } + } + } + + /// Visit a value which is evaluated, but whose value is ignored. + void VisitIgnoredValue(const Expr *E) { + EvaluateIgnoredValue(Info, E); + } +}; + +} + +//===----------------------------------------------------------------------===// +// Common base class for lvalue and temporary evaluation. +//===----------------------------------------------------------------------===// +namespace { +template<class Derived> +class LValueExprEvaluatorBase + : public ExprEvaluatorBase<Derived> { +protected: + LValue &Result; + typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy; + typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy; + + bool Success(APValue::LValueBase B) { + Result.set(B); + return true; + } + +public: + LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result) : + ExprEvaluatorBaseTy(Info), Result(Result) {} + + bool Success(const APValue &V, const Expr *E) { + Result.setFrom(this->Info.Ctx, V); + return true; + } + + bool VisitMemberExpr(const MemberExpr *E) { + // Handle non-static data members. + QualType BaseTy; + if (E->isArrow()) { + if (!EvaluatePointer(E->getBase(), Result, this->Info)) + return false; + BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType(); + } else if (E->getBase()->isRValue()) { + assert(E->getBase()->getType()->isRecordType()); + if (!EvaluateTemporary(E->getBase(), Result, this->Info)) + return false; + BaseTy = E->getBase()->getType(); + } else { + if (!this->Visit(E->getBase())) + return false; + BaseTy = E->getBase()->getType(); + } + + const ValueDecl *MD = E->getMemberDecl(); + if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) { + assert(BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() == + FD->getParent()->getCanonicalDecl() && "record / field mismatch"); + (void)BaseTy; + if (!HandleLValueMember(this->Info, E, Result, FD)) + return false; + } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) { + if (!HandleLValueIndirectMember(this->Info, E, Result, IFD)) + return false; + } else + return this->Error(E); + + if (MD->getType()->isReferenceType()) { + APValue RefValue; + if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result, + RefValue)) + return false; + return Success(RefValue, E); + } + return true; + } + + bool VisitBinaryOperator(const BinaryOperator *E) { + switch (E->getOpcode()) { + default: + return ExprEvaluatorBaseTy::VisitBinaryOperator(E); + + case BO_PtrMemD: + case BO_PtrMemI: + return HandleMemberPointerAccess(this->Info, E, Result); + } + } + + bool VisitCastExpr(const CastExpr *E) { + switch (E->getCastKind()) { + default: + return ExprEvaluatorBaseTy::VisitCastExpr(E); + + case CK_DerivedToBase: + case CK_UncheckedDerivedToBase: + if (!this->Visit(E->getSubExpr())) + return false; + + // Now figure out the necessary offset to add to the base LV to get from + // the derived class to the base class. + return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(), + Result); + } + } +}; +} + +//===----------------------------------------------------------------------===// +// LValue Evaluation +// +// This is used for evaluating lvalues (in C and C++), xvalues (in C++11), +// function designators (in C), decl references to void objects (in C), and +// temporaries (if building with -Wno-address-of-temporary). +// +// LValue evaluation produces values comprising a base expression of one of the +// following types: +// - Declarations +// * VarDecl +// * FunctionDecl +// - Literals +// * CompoundLiteralExpr in C +// * StringLiteral +// * CXXTypeidExpr +// * PredefinedExpr +// * ObjCStringLiteralExpr +// * ObjCEncodeExpr +// * AddrLabelExpr +// * BlockExpr +// * CallExpr for a MakeStringConstant builtin +// - Locals and temporaries +// * MaterializeTemporaryExpr +// * Any Expr, with a CallIndex indicating the function in which the temporary +// was evaluated, for cases where the MaterializeTemporaryExpr is missing +// from the AST (FIXME). +// * A MaterializeTemporaryExpr that has static storage duration, with no +// CallIndex, for a lifetime-extended temporary. +// plus an offset in bytes. +//===----------------------------------------------------------------------===// +namespace { +class LValueExprEvaluator + : public LValueExprEvaluatorBase<LValueExprEvaluator> { +public: + LValueExprEvaluator(EvalInfo &Info, LValue &Result) : + LValueExprEvaluatorBaseTy(Info, Result) {} + + bool VisitVarDecl(const Expr *E, const VarDecl *VD); + bool VisitUnaryPreIncDec(const UnaryOperator *UO); + + bool VisitDeclRefExpr(const DeclRefExpr *E); + bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); } + bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E); + bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E); + bool VisitMemberExpr(const MemberExpr *E); + bool VisitStringLiteral(const StringLiteral *E) { return Success(E); } + bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); } + bool VisitCXXTypeidExpr(const CXXTypeidExpr *E); + bool VisitCXXUuidofExpr(const CXXUuidofExpr *E); + bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E); + bool VisitUnaryDeref(const UnaryOperator *E); + bool VisitUnaryReal(const UnaryOperator *E); + bool VisitUnaryImag(const UnaryOperator *E); + bool VisitUnaryPreInc(const UnaryOperator *UO) { + return VisitUnaryPreIncDec(UO); + } + bool VisitUnaryPreDec(const UnaryOperator *UO) { + return VisitUnaryPreIncDec(UO); + } + bool VisitBinAssign(const BinaryOperator *BO); + bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO); + + bool VisitCastExpr(const CastExpr *E) { + switch (E->getCastKind()) { + default: + return LValueExprEvaluatorBaseTy::VisitCastExpr(E); + + case CK_LValueBitCast: + this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; + if (!Visit(E->getSubExpr())) + return false; + Result.Designator.setInvalid(); + return true; + + case CK_BaseToDerived: + if (!Visit(E->getSubExpr())) + return false; + return HandleBaseToDerivedCast(Info, E, Result); + } + } +}; +} // end anonymous namespace + +/// Evaluate an expression as an lvalue. This can be legitimately called on +/// expressions which are not glvalues, in two cases: +/// * function designators in C, and +/// * "extern void" objects +static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info) { + assert(E->isGLValue() || E->getType()->isFunctionType() || + E->getType()->isVoidType()); + return LValueExprEvaluator(Info, Result).Visit(E); +} + +bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) { + if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl())) + return Success(FD); + if (const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl())) + return VisitVarDecl(E, VD); + return Error(E); +} + +bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) { + CallStackFrame *Frame = nullptr; + if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) + Frame = Info.CurrentCall; + + if (!VD->getType()->isReferenceType()) { + if (Frame) { + Result.set(VD, Frame->Index); + return true; + } + return Success(VD); + } + + APValue *V; + if (!evaluateVarDeclInit(Info, E, VD, Frame, V)) + return false; + if (V->isUninit()) { + if (!Info.checkingPotentialConstantExpression()) + Info.Diag(E, diag::note_constexpr_use_uninit_reference); + return false; + } + return Success(*V, E); +} + +bool LValueExprEvaluator::VisitMaterializeTemporaryExpr( + const MaterializeTemporaryExpr *E) { + // Walk through the expression to find the materialized temporary itself. + SmallVector<const Expr *, 2> CommaLHSs; + SmallVector<SubobjectAdjustment, 2> Adjustments; + const Expr *Inner = E->GetTemporaryExpr()-> + skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); + + // If we passed any comma operators, evaluate their LHSs. + for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I) + if (!EvaluateIgnoredValue(Info, CommaLHSs[I])) + return false; + + // A materialized temporary with static storage duration can appear within the + // result of a constant expression evaluation, so we need to preserve its + // value for use outside this evaluation. + APValue *Value; + if (E->getStorageDuration() == SD_Static) { + Value = Info.Ctx.getMaterializedTemporaryValue(E, true); + *Value = APValue(); + Result.set(E); + } else { + Value = &Info.CurrentCall-> + createTemporary(E, E->getStorageDuration() == SD_Automatic); + Result.set(E, Info.CurrentCall->Index); + } + + QualType Type = Inner->getType(); + + // Materialize the temporary itself. + if (!EvaluateInPlace(*Value, Info, Result, Inner) || + (E->getStorageDuration() == SD_Static && + !CheckConstantExpression(Info, E->getExprLoc(), Type, *Value))) { + *Value = APValue(); + return false; + } + + // Adjust our lvalue to refer to the desired subobject. + for (unsigned I = Adjustments.size(); I != 0; /**/) { + --I; + switch (Adjustments[I].Kind) { + case SubobjectAdjustment::DerivedToBaseAdjustment: + if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath, + Type, Result)) + return false; + Type = Adjustments[I].DerivedToBase.BasePath->getType(); + break; + + case SubobjectAdjustment::FieldAdjustment: + if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field)) + return false; + Type = Adjustments[I].Field->getType(); + break; + + case SubobjectAdjustment::MemberPointerAdjustment: + if (!HandleMemberPointerAccess(this->Info, Type, Result, + Adjustments[I].Ptr.RHS)) + return false; + Type = Adjustments[I].Ptr.MPT->getPointeeType(); + break; + } + } + + return true; +} + +bool +LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { + assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?"); + // Defer visiting the literal until the lvalue-to-rvalue conversion. We can + // only see this when folding in C, so there's no standard to follow here. + return Success(E); +} + +bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) { + if (!E->isPotentiallyEvaluated()) + return Success(E); + + Info.Diag(E, diag::note_constexpr_typeid_polymorphic) + << E->getExprOperand()->getType() + << E->getExprOperand()->getSourceRange(); + return false; +} + +bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) { + return Success(E); +} + +bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) { + // Handle static data members. + if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) { + VisitIgnoredValue(E->getBase()); + return VisitVarDecl(E, VD); + } + + // Handle static member functions. + if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) { + if (MD->isStatic()) { + VisitIgnoredValue(E->getBase()); + return Success(MD); + } + } + + // Handle non-static data members. + return LValueExprEvaluatorBaseTy::VisitMemberExpr(E); +} + +bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) { + // FIXME: Deal with vectors as array subscript bases. + if (E->getBase()->getType()->isVectorType()) + return Error(E); + + if (!EvaluatePointer(E->getBase(), Result, Info)) + return false; + + APSInt Index; + if (!EvaluateInteger(E->getIdx(), Index, Info)) + return false; + + return HandleLValueArrayAdjustment(Info, E, Result, E->getType(), + getExtValue(Index)); +} + +bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) { + return EvaluatePointer(E->getSubExpr(), Result, Info); +} + +bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { + if (!Visit(E->getSubExpr())) + return false; + // __real is a no-op on scalar lvalues. + if (E->getSubExpr()->getType()->isAnyComplexType()) + HandleLValueComplexElement(Info, E, Result, E->getType(), false); + return true; +} + +bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { + assert(E->getSubExpr()->getType()->isAnyComplexType() && + "lvalue __imag__ on scalar?"); + if (!Visit(E->getSubExpr())) + return false; + HandleLValueComplexElement(Info, E, Result, E->getType(), true); + return true; +} + +bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) { + if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) + return Error(UO); + + if (!this->Visit(UO->getSubExpr())) + return false; + + return handleIncDec( + this->Info, UO, Result, UO->getSubExpr()->getType(), + UO->isIncrementOp(), nullptr); +} + +bool LValueExprEvaluator::VisitCompoundAssignOperator( + const CompoundAssignOperator *CAO) { + if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) + return Error(CAO); + + APValue RHS; + + // The overall lvalue result is the result of evaluating the LHS. + if (!this->Visit(CAO->getLHS())) { + if (Info.keepEvaluatingAfterFailure()) + Evaluate(RHS, this->Info, CAO->getRHS()); + return false; + } + + if (!Evaluate(RHS, this->Info, CAO->getRHS())) + return false; + + return handleCompoundAssignment( + this->Info, CAO, + Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(), + CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS); +} + +bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) { + if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) + return Error(E); + + APValue NewVal; + + if (!this->Visit(E->getLHS())) { + if (Info.keepEvaluatingAfterFailure()) + Evaluate(NewVal, this->Info, E->getRHS()); + return false; + } + + if (!Evaluate(NewVal, this->Info, E->getRHS())) + return false; + + return handleAssignment(this->Info, E, Result, E->getLHS()->getType(), + NewVal); +} + +//===----------------------------------------------------------------------===// +// Pointer Evaluation +//===----------------------------------------------------------------------===// + +namespace { +class PointerExprEvaluator + : public ExprEvaluatorBase<PointerExprEvaluator> { + LValue &Result; + + bool Success(const Expr *E) { + Result.set(E); + return true; + } +public: + + PointerExprEvaluator(EvalInfo &info, LValue &Result) + : ExprEvaluatorBaseTy(info), Result(Result) {} + + bool Success(const APValue &V, const Expr *E) { + Result.setFrom(Info.Ctx, V); + return true; + } + bool ZeroInitialization(const Expr *E) { + return Success((Expr*)nullptr); + } + + bool VisitBinaryOperator(const BinaryOperator *E); + bool VisitCastExpr(const CastExpr* E); + bool VisitUnaryAddrOf(const UnaryOperator *E); + bool VisitObjCStringLiteral(const ObjCStringLiteral *E) + { return Success(E); } + bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) + { return Success(E); } + bool VisitAddrLabelExpr(const AddrLabelExpr *E) + { return Success(E); } + bool VisitCallExpr(const CallExpr *E); + bool VisitBlockExpr(const BlockExpr *E) { + if (!E->getBlockDecl()->hasCaptures()) + return Success(E); + return Error(E); + } + bool VisitCXXThisExpr(const CXXThisExpr *E) { + // Can't look at 'this' when checking a potential constant expression. + if (Info.checkingPotentialConstantExpression()) + return false; + if (!Info.CurrentCall->This) { + if (Info.getLangOpts().CPlusPlus11) + Info.Diag(E, diag::note_constexpr_this) << E->isImplicit(); + else + Info.Diag(E); + return false; + } + Result = *Info.CurrentCall->This; + return true; + } + + // FIXME: Missing: @protocol, @selector +}; +} // end anonymous namespace + +static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info) { + assert(E->isRValue() && E->getType()->hasPointerRepresentation()); + return PointerExprEvaluator(Info, Result).Visit(E); +} + +bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { + if (E->getOpcode() != BO_Add && + E->getOpcode() != BO_Sub) + return ExprEvaluatorBaseTy::VisitBinaryOperator(E); + + const Expr *PExp = E->getLHS(); + const Expr *IExp = E->getRHS(); + if (IExp->getType()->isPointerType()) + std::swap(PExp, IExp); + + bool EvalPtrOK = EvaluatePointer(PExp, Result, Info); + if (!EvalPtrOK && !Info.keepEvaluatingAfterFailure()) + return false; + + llvm::APSInt Offset; + if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK) + return false; + + int64_t AdditionalOffset = getExtValue(Offset); + if (E->getOpcode() == BO_Sub) + AdditionalOffset = -AdditionalOffset; + + QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType(); + return HandleLValueArrayAdjustment(Info, E, Result, Pointee, + AdditionalOffset); +} + +bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { + return EvaluateLValue(E->getSubExpr(), Result, Info); +} + +bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) { + const Expr* SubExpr = E->getSubExpr(); + + switch (E->getCastKind()) { + default: + break; + + case CK_BitCast: + case CK_CPointerToObjCPointerCast: + case CK_BlockPointerToObjCPointerCast: + case CK_AnyPointerToBlockPointerCast: + case CK_AddressSpaceConversion: + if (!Visit(SubExpr)) + return false; + // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are + // permitted in constant expressions in C++11. Bitcasts from cv void* are + // also static_casts, but we disallow them as a resolution to DR1312. + if (!E->getType()->isVoidPointerType()) { + Result.Designator.setInvalid(); + if (SubExpr->getType()->isVoidPointerType()) + CCEDiag(E, diag::note_constexpr_invalid_cast) + << 3 << SubExpr->getType(); + else + CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; + } + return true; + + case CK_DerivedToBase: + case CK_UncheckedDerivedToBase: + if (!EvaluatePointer(E->getSubExpr(), Result, Info)) + return false; + if (!Result.Base && Result.Offset.isZero()) + return true; + + // Now figure out the necessary offset to add to the base LV to get from + // the derived class to the base class. + return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()-> + castAs<PointerType>()->getPointeeType(), + Result); + + case CK_BaseToDerived: + if (!Visit(E->getSubExpr())) + return false; + if (!Result.Base && Result.Offset.isZero()) + return true; + return HandleBaseToDerivedCast(Info, E, Result); + + case CK_NullToPointer: + VisitIgnoredValue(E->getSubExpr()); + return ZeroInitialization(E); + + case CK_IntegralToPointer: { + CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; + + APValue Value; + if (!EvaluateIntegerOrLValue(SubExpr, Value, Info)) + break; + + if (Value.isInt()) { + unsigned Size = Info.Ctx.getTypeSize(E->getType()); + uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue(); + Result.Base = (Expr*)nullptr; + Result.Offset = CharUnits::fromQuantity(N); + Result.CallIndex = 0; + Result.Designator.setInvalid(); + return true; + } else { + // Cast is of an lvalue, no need to change value. + Result.setFrom(Info.Ctx, Value); + return true; + } + } + case CK_ArrayToPointerDecay: + if (SubExpr->isGLValue()) { + if (!EvaluateLValue(SubExpr, Result, Info)) + return false; + } else { + Result.set(SubExpr, Info.CurrentCall->Index); + if (!EvaluateInPlace(Info.CurrentCall->createTemporary(SubExpr, false), + Info, Result, SubExpr)) + return false; + } + // The result is a pointer to the first element of the array. + if (const ConstantArrayType *CAT + = Info.Ctx.getAsConstantArrayType(SubExpr->getType())) + Result.addArray(Info, E, CAT); + else + Result.Designator.setInvalid(); + return true; + + case CK_FunctionToPointerDecay: + return EvaluateLValue(SubExpr, Result, Info); + } + + return ExprEvaluatorBaseTy::VisitCastExpr(E); +} + +static CharUnits GetAlignOfType(EvalInfo &Info, QualType T) { + // C++ [expr.alignof]p3: + // When alignof is applied to a reference type, the result is the + // alignment of the referenced type. + if (const ReferenceType *Ref = T->getAs<ReferenceType>()) + T = Ref->getPointeeType(); + + // __alignof is defined to return the preferred alignment. + return Info.Ctx.toCharUnitsFromBits( + Info.Ctx.getPreferredTypeAlign(T.getTypePtr())); +} + +static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E) { + E = E->IgnoreParens(); + + // The kinds of expressions that we have special-case logic here for + // should be kept up to date with the special checks for those + // expressions in Sema. + + // alignof decl is always accepted, even if it doesn't make sense: we default + // to 1 in those cases. + if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) + return Info.Ctx.getDeclAlign(DRE->getDecl(), + /*RefAsPointee*/true); + + if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) + return Info.Ctx.getDeclAlign(ME->getMemberDecl(), + /*RefAsPointee*/true); + + return GetAlignOfType(Info, E->getType()); +} + +bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) { + if (IsStringLiteralCall(E)) + return Success(E); + + switch (E->getBuiltinCallee()) { + case Builtin::BI__builtin_addressof: + return EvaluateLValue(E->getArg(0), Result, Info); + case Builtin::BI__builtin_assume_aligned: { + // We need to be very careful here because: if the pointer does not have the + // asserted alignment, then the behavior is undefined, and undefined + // behavior is non-constant. + if (!EvaluatePointer(E->getArg(0), Result, Info)) + return false; + + LValue OffsetResult(Result); + APSInt Alignment; + if (!EvaluateInteger(E->getArg(1), Alignment, Info)) + return false; + CharUnits Align = CharUnits::fromQuantity(getExtValue(Alignment)); + + if (E->getNumArgs() > 2) { + APSInt Offset; + if (!EvaluateInteger(E->getArg(2), Offset, Info)) + return false; + + int64_t AdditionalOffset = -getExtValue(Offset); + OffsetResult.Offset += CharUnits::fromQuantity(AdditionalOffset); + } + + // If there is a base object, then it must have the correct alignment. + if (OffsetResult.Base) { + CharUnits BaseAlignment; + if (const ValueDecl *VD = + OffsetResult.Base.dyn_cast<const ValueDecl*>()) { + BaseAlignment = Info.Ctx.getDeclAlign(VD); + } else { + BaseAlignment = + GetAlignOfExpr(Info, OffsetResult.Base.get<const Expr*>()); + } + + if (BaseAlignment < Align) { + Result.Designator.setInvalid(); + // FIXME: Quantities here cast to integers because the plural modifier + // does not work on APSInts yet. + CCEDiag(E->getArg(0), + diag::note_constexpr_baa_insufficient_alignment) << 0 + << (int) BaseAlignment.getQuantity() + << (unsigned) getExtValue(Alignment); + return false; + } + } + + // The offset must also have the correct alignment. + if (OffsetResult.Offset.RoundUpToAlignment(Align) != OffsetResult.Offset) { + Result.Designator.setInvalid(); + APSInt Offset(64, false); + Offset = OffsetResult.Offset.getQuantity(); + + if (OffsetResult.Base) + CCEDiag(E->getArg(0), + diag::note_constexpr_baa_insufficient_alignment) << 1 + << (int) getExtValue(Offset) << (unsigned) getExtValue(Alignment); + else + CCEDiag(E->getArg(0), + diag::note_constexpr_baa_value_insufficient_alignment) + << Offset << (unsigned) getExtValue(Alignment); + + return false; + } + + return true; + } + default: + return ExprEvaluatorBaseTy::VisitCallExpr(E); + } +} + +//===----------------------------------------------------------------------===// +// Member Pointer Evaluation +//===----------------------------------------------------------------------===// + +namespace { +class MemberPointerExprEvaluator + : public ExprEvaluatorBase<MemberPointerExprEvaluator> { + MemberPtr &Result; + + bool Success(const ValueDecl *D) { + Result = MemberPtr(D); + return true; + } +public: + + MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result) + : ExprEvaluatorBaseTy(Info), Result(Result) {} + + bool Success(const APValue &V, const Expr *E) { + Result.setFrom(V); + return true; + } + bool ZeroInitialization(const Expr *E) { + return Success((const ValueDecl*)nullptr); + } + + bool VisitCastExpr(const CastExpr *E); + bool VisitUnaryAddrOf(const UnaryOperator *E); +}; +} // end anonymous namespace + +static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, + EvalInfo &Info) { + assert(E->isRValue() && E->getType()->isMemberPointerType()); + return MemberPointerExprEvaluator(Info, Result).Visit(E); +} + +bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) { + switch (E->getCastKind()) { + default: + return ExprEvaluatorBaseTy::VisitCastExpr(E); + + case CK_NullToMemberPointer: + VisitIgnoredValue(E->getSubExpr()); + return ZeroInitialization(E); + + case CK_BaseToDerivedMemberPointer: { + if (!Visit(E->getSubExpr())) + return false; + if (E->path_empty()) + return true; + // Base-to-derived member pointer casts store the path in derived-to-base + // order, so iterate backwards. The CXXBaseSpecifier also provides us with + // the wrong end of the derived->base arc, so stagger the path by one class. + typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter; + for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin()); + PathI != PathE; ++PathI) { + assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); + const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl(); + if (!Result.castToDerived(Derived)) + return Error(E); + } + const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass(); + if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl())) + return Error(E); + return true; + } + + case CK_DerivedToBaseMemberPointer: + if (!Visit(E->getSubExpr())) + return false; + for (CastExpr::path_const_iterator PathI = E->path_begin(), + PathE = E->path_end(); PathI != PathE; ++PathI) { + assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); + const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); + if (!Result.castToBase(Base)) + return Error(E); + } + return true; + } +} + +bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { + // C++11 [expr.unary.op]p3 has very strict rules on how the address of a + // member can be formed. + return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl()); +} + +//===----------------------------------------------------------------------===// +// Record Evaluation +//===----------------------------------------------------------------------===// + +namespace { + class RecordExprEvaluator + : public ExprEvaluatorBase<RecordExprEvaluator> { + const LValue &This; + APValue &Result; + public: + + RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result) + : ExprEvaluatorBaseTy(info), This(This), Result(Result) {} + + bool Success(const APValue &V, const Expr *E) { + Result = V; + return true; + } + bool ZeroInitialization(const Expr *E); + + bool VisitCastExpr(const CastExpr *E); + bool VisitInitListExpr(const InitListExpr *E); + bool VisitCXXConstructExpr(const CXXConstructExpr *E); + bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E); + }; +} + +/// Perform zero-initialization on an object of non-union class type. +/// C++11 [dcl.init]p5: +/// To zero-initialize an object or reference of type T means: +/// [...] +/// -- if T is a (possibly cv-qualified) non-union class type, +/// each non-static data member and each base-class subobject is +/// zero-initialized +static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E, + const RecordDecl *RD, + const LValue &This, APValue &Result) { + assert(!RD->isUnion() && "Expected non-union class type"); + const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD); + Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0, + std::distance(RD->field_begin(), RD->field_end())); + + if (RD->isInvalidDecl()) return false; + const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); + + if (CD) { + unsigned Index = 0; + for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), + End = CD->bases_end(); I != End; ++I, ++Index) { + const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl(); + LValue Subobject = This; + if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout)) + return false; + if (!HandleClassZeroInitialization(Info, E, Base, Subobject, + Result.getStructBase(Index))) + return false; + } + } + + for (const auto *I : RD->fields()) { + // -- if T is a reference type, no initialization is performed. + if (I->getType()->isReferenceType()) + continue; + + LValue Subobject = This; + if (!HandleLValueMember(Info, E, Subobject, I, &Layout)) + return false; + + ImplicitValueInitExpr VIE(I->getType()); + if (!EvaluateInPlace( + Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE)) + return false; + } + + return true; +} + +bool RecordExprEvaluator::ZeroInitialization(const Expr *E) { + const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl(); + if (RD->isInvalidDecl()) return false; + if (RD->isUnion()) { + // C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the + // object's first non-static named data member is zero-initialized + RecordDecl::field_iterator I = RD->field_begin(); + if (I == RD->field_end()) { + Result = APValue((const FieldDecl*)nullptr); + return true; + } + + LValue Subobject = This; + if (!HandleLValueMember(Info, E, Subobject, *I)) + return false; + Result = APValue(*I); + ImplicitValueInitExpr VIE(I->getType()); + return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE); + } + + if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) { + Info.Diag(E, diag::note_constexpr_virtual_base) << RD; + return false; + } + + return HandleClassZeroInitialization(Info, E, RD, This, Result); +} + +bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) { + switch (E->getCastKind()) { + default: + return ExprEvaluatorBaseTy::VisitCastExpr(E); + + case CK_ConstructorConversion: + return Visit(E->getSubExpr()); + + case CK_DerivedToBase: + case CK_UncheckedDerivedToBase: { + APValue DerivedObject; + if (!Evaluate(DerivedObject, Info, E->getSubExpr())) + return false; + if (!DerivedObject.isStruct()) + return Error(E->getSubExpr()); + + // Derived-to-base rvalue conversion: just slice off the derived part. + APValue *Value = &DerivedObject; + const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl(); + for (CastExpr::path_const_iterator PathI = E->path_begin(), + PathE = E->path_end(); PathI != PathE; ++PathI) { + assert(!(*PathI)->isVirtual() && "record rvalue with virtual base"); + const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); + Value = &Value->getStructBase(getBaseIndex(RD, Base)); + RD = Base; + } + Result = *Value; + return true; + } + } +} + +bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) { + const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl(); + if (RD->isInvalidDecl()) return false; + const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); + + if (RD->isUnion()) { + const FieldDecl *Field = E->getInitializedFieldInUnion(); + Result = APValue(Field); + if (!Field) + return true; + + // If the initializer list for a union does not contain any elements, the + // first element of the union is value-initialized. + // FIXME: The element should be initialized from an initializer list. + // Is this difference ever observable for initializer lists which + // we don't build? + ImplicitValueInitExpr VIE(Field->getType()); + const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE; + + LValue Subobject = This; + if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout)) + return false; + + // Temporarily override This, in case there's a CXXDefaultInitExpr in here. + ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, + isa<CXXDefaultInitExpr>(InitExpr)); + + return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr); + } + + assert((!isa<CXXRecordDecl>(RD) || !cast<CXXRecordDecl>(RD)->getNumBases()) && + "initializer list for class with base classes"); + Result = APValue(APValue::UninitStruct(), 0, + std::distance(RD->field_begin(), RD->field_end())); + unsigned ElementNo = 0; + bool Success = true; + for (const auto *Field : RD->fields()) { + // Anonymous bit-fields are not considered members of the class for + // purposes of aggregate initialization. + if (Field->isUnnamedBitfield()) + continue; + + LValue Subobject = This; + + bool HaveInit = ElementNo < E->getNumInits(); + + // FIXME: Diagnostics here should point to the end of the initializer + // list, not the start. + if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E, + Subobject, Field, &Layout)) + return false; + + // Perform an implicit value-initialization for members beyond the end of + // the initializer list. + ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType()); + const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE; + + // Temporarily override This, in case there's a CXXDefaultInitExpr in here. + ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, + isa<CXXDefaultInitExpr>(Init)); + + APValue &FieldVal = Result.getStructField(Field->getFieldIndex()); + if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) || + (Field->isBitField() && !truncateBitfieldValue(Info, Init, + FieldVal, Field))) { + if (!Info.keepEvaluatingAfterFailure()) + return false; + Success = false; + } + } + + return Success; +} + +bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { + const CXXConstructorDecl *FD = E->getConstructor(); + if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false; + + bool ZeroInit = E->requiresZeroInitialization(); + if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { + // If we've already performed zero-initialization, we're already done. + if (!Result.isUninit()) + return true; + + // We can get here in two different ways: + // 1) We're performing value-initialization, and should zero-initialize + // the object, or + // 2) We're performing default-initialization of an object with a trivial + // constexpr default constructor, in which case we should start the + // lifetimes of all the base subobjects (there can be no data member + // subobjects in this case) per [basic.life]p1. + // Either way, ZeroInitialization is appropriate. + return ZeroInitialization(E); + } + + const FunctionDecl *Definition = nullptr; + FD->getBody(Definition); + + if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition)) + return false; + + // Avoid materializing a temporary for an elidable copy/move constructor. + if (E->isElidable() && !ZeroInit) + if (const MaterializeTemporaryExpr *ME + = dyn_cast<MaterializeTemporaryExpr>(E->getArg(0))) + return Visit(ME->GetTemporaryExpr()); + + if (ZeroInit && !ZeroInitialization(E)) + return false; + + auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs()); + return HandleConstructorCall(E->getExprLoc(), This, Args, + cast<CXXConstructorDecl>(Definition), Info, + Result); +} + +bool RecordExprEvaluator::VisitCXXStdInitializerListExpr( + const CXXStdInitializerListExpr *E) { + const ConstantArrayType *ArrayType = + Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType()); + + LValue Array; + if (!EvaluateLValue(E->getSubExpr(), Array, Info)) + return false; + + // Get a pointer to the first element of the array. + Array.addArray(Info, E, ArrayType); + + // FIXME: Perform the checks on the field types in SemaInit. + RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl(); + RecordDecl::field_iterator Field = Record->field_begin(); + if (Field == Record->field_end()) + return Error(E); + + // Start pointer. + if (!Field->getType()->isPointerType() || + !Info.Ctx.hasSameType(Field->getType()->getPointeeType(), + ArrayType->getElementType())) + return Error(E); + + // FIXME: What if the initializer_list type has base classes, etc? + Result = APValue(APValue::UninitStruct(), 0, 2); + Array.moveInto(Result.getStructField(0)); + + if (++Field == Record->field_end()) + return Error(E); + + if (Field->getType()->isPointerType() && + Info.Ctx.hasSameType(Field->getType()->getPointeeType(), + ArrayType->getElementType())) { + // End pointer. + if (!HandleLValueArrayAdjustment(Info, E, Array, + ArrayType->getElementType(), + ArrayType->getSize().getZExtValue())) + return false; + Array.moveInto(Result.getStructField(1)); + } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType())) + // Length. + Result.getStructField(1) = APValue(APSInt(ArrayType->getSize())); + else + return Error(E); + + if (++Field != Record->field_end()) + return Error(E); + + return true; +} + +static bool EvaluateRecord(const Expr *E, const LValue &This, + APValue &Result, EvalInfo &Info) { + assert(E->isRValue() && E->getType()->isRecordType() && + "can't evaluate expression as a record rvalue"); + return RecordExprEvaluator(Info, This, Result).Visit(E); +} + +//===----------------------------------------------------------------------===// +// Temporary Evaluation +// +// Temporaries are represented in the AST as rvalues, but generally behave like +// lvalues. The full-object of which the temporary is a subobject is implicitly +// materialized so that a reference can bind to it. +//===----------------------------------------------------------------------===// +namespace { +class TemporaryExprEvaluator + : public LValueExprEvaluatorBase<TemporaryExprEvaluator> { +public: + TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) : + LValueExprEvaluatorBaseTy(Info, Result) {} + + /// Visit an expression which constructs the value of this temporary. + bool VisitConstructExpr(const Expr *E) { + Result.set(E, Info.CurrentCall->Index); + return EvaluateInPlace(Info.CurrentCall->createTemporary(E, false), + Info, Result, E); + } + + bool VisitCastExpr(const CastExpr *E) { + switch (E->getCastKind()) { + default: + return LValueExprEvaluatorBaseTy::VisitCastExpr(E); + + case CK_ConstructorConversion: + return VisitConstructExpr(E->getSubExpr()); + } + } + bool VisitInitListExpr(const InitListExpr *E) { + return VisitConstructExpr(E); + } + bool VisitCXXConstructExpr(const CXXConstructExpr *E) { + return VisitConstructExpr(E); + } + bool VisitCallExpr(const CallExpr *E) { + return VisitConstructExpr(E); + } + bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) { + return VisitConstructExpr(E); + } +}; +} // end anonymous namespace + +/// Evaluate an expression of record type as a temporary. +static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) { + assert(E->isRValue() && E->getType()->isRecordType()); + return TemporaryExprEvaluator(Info, Result).Visit(E); +} + +//===----------------------------------------------------------------------===// +// Vector Evaluation +//===----------------------------------------------------------------------===// + +namespace { + class VectorExprEvaluator + : public ExprEvaluatorBase<VectorExprEvaluator> { + APValue &Result; + public: + + VectorExprEvaluator(EvalInfo &info, APValue &Result) + : ExprEvaluatorBaseTy(info), Result(Result) {} + + bool Success(const ArrayRef<APValue> &V, const Expr *E) { + assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements()); + // FIXME: remove this APValue copy. + Result = APValue(V.data(), V.size()); + return true; + } + bool Success(const APValue &V, const Expr *E) { + assert(V.isVector()); + Result = V; + return true; + } + bool ZeroInitialization(const Expr *E); + + bool VisitUnaryReal(const UnaryOperator *E) + { return Visit(E->getSubExpr()); } + bool VisitCastExpr(const CastExpr* E); + bool VisitInitListExpr(const InitListExpr *E); + bool VisitUnaryImag(const UnaryOperator *E); + // FIXME: Missing: unary -, unary ~, binary add/sub/mul/div, + // binary comparisons, binary and/or/xor, + // shufflevector, ExtVectorElementExpr + }; +} // end anonymous namespace + +static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) { + assert(E->isRValue() && E->getType()->isVectorType() &&"not a vector rvalue"); + return VectorExprEvaluator(Info, Result).Visit(E); +} + +bool VectorExprEvaluator::VisitCastExpr(const CastExpr* E) { + const VectorType *VTy = E->getType()->castAs<VectorType>(); + unsigned NElts = VTy->getNumElements(); + + const Expr *SE = E->getSubExpr(); + QualType SETy = SE->getType(); + + switch (E->getCastKind()) { + case CK_VectorSplat: { + APValue Val = APValue(); + if (SETy->isIntegerType()) { + APSInt IntResult; + if (!EvaluateInteger(SE, IntResult, Info)) + return false; + Val = APValue(IntResult); + } else if (SETy->isRealFloatingType()) { + APFloat F(0.0); + if (!EvaluateFloat(SE, F, Info)) + return false; + Val = APValue(F); + } else { + return Error(E); + } + + // Splat and create vector APValue. + SmallVector<APValue, 4> Elts(NElts, Val); + return Success(Elts, E); + } + case CK_BitCast: { + // Evaluate the operand into an APInt we can extract from. + llvm::APInt SValInt; + if (!EvalAndBitcastToAPInt(Info, SE, SValInt)) + return false; + // Extract the elements + QualType EltTy = VTy->getElementType(); + unsigned EltSize = Info.Ctx.getTypeSize(EltTy); + bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); + SmallVector<APValue, 4> Elts; + if (EltTy->isRealFloatingType()) { + const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy); + unsigned FloatEltSize = EltSize; + if (&Sem == &APFloat::x87DoubleExtended) + FloatEltSize = 80; + for (unsigned i = 0; i < NElts; i++) { + llvm::APInt Elt; + if (BigEndian) + Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize); + else + Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize); + Elts.push_back(APValue(APFloat(Sem, Elt))); + } + } else if (EltTy->isIntegerType()) { + for (unsigned i = 0; i < NElts; i++) { + llvm::APInt Elt; + if (BigEndian) + Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize); + else + Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize); + Elts.push_back(APValue(APSInt(Elt, EltTy->isSignedIntegerType()))); + } + } else { + return Error(E); + } + return Success(Elts, E); + } + default: + return ExprEvaluatorBaseTy::VisitCastExpr(E); + } +} + +bool +VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) { + const VectorType *VT = E->getType()->castAs<VectorType>(); + unsigned NumInits = E->getNumInits(); + unsigned NumElements = VT->getNumElements(); + + QualType EltTy = VT->getElementType(); + SmallVector<APValue, 4> Elements; + + // The number of initializers can be less than the number of + // vector elements. For OpenCL, this can be due to nested vector + // initialization. For GCC compatibility, missing trailing elements + // should be initialized with zeroes. + unsigned CountInits = 0, CountElts = 0; + while (CountElts < NumElements) { + // Handle nested vector initialization. + if (CountInits < NumInits + && E->getInit(CountInits)->getType()->isVectorType()) { + APValue v; + if (!EvaluateVector(E->getInit(CountInits), v, Info)) + return Error(E); + unsigned vlen = v.getVectorLength(); + for (unsigned j = 0; j < vlen; j++) + Elements.push_back(v.getVectorElt(j)); + CountElts += vlen; + } else if (EltTy->isIntegerType()) { + llvm::APSInt sInt(32); + if (CountInits < NumInits) { + if (!EvaluateInteger(E->getInit(CountInits), sInt, Info)) + return false; + } else // trailing integer zero. + sInt = Info.Ctx.MakeIntValue(0, EltTy); + Elements.push_back(APValue(sInt)); + CountElts++; + } else { + llvm::APFloat f(0.0); + if (CountInits < NumInits) { + if (!EvaluateFloat(E->getInit(CountInits), f, Info)) + return false; + } else // trailing float zero. + f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)); + Elements.push_back(APValue(f)); + CountElts++; + } + CountInits++; + } + return Success(Elements, E); +} + +bool +VectorExprEvaluator::ZeroInitialization(const Expr *E) { + const VectorType *VT = E->getType()->getAs<VectorType>(); + QualType EltTy = VT->getElementType(); + APValue ZeroElement; + if (EltTy->isIntegerType()) + ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy)); + else + ZeroElement = + APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy))); + + SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement); + return Success(Elements, E); +} + +bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { + VisitIgnoredValue(E->getSubExpr()); + return ZeroInitialization(E); +} + +//===----------------------------------------------------------------------===// +// Array Evaluation +//===----------------------------------------------------------------------===// + +namespace { + class ArrayExprEvaluator + : public ExprEvaluatorBase<ArrayExprEvaluator> { + const LValue &This; + APValue &Result; + public: + + ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result) + : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {} + + bool Success(const APValue &V, const Expr *E) { + assert((V.isArray() || V.isLValue()) && + "expected array or string literal"); + Result = V; + return true; + } + + bool ZeroInitialization(const Expr *E) { + const ConstantArrayType *CAT = + Info.Ctx.getAsConstantArrayType(E->getType()); + if (!CAT) + return Error(E); + + Result = APValue(APValue::UninitArray(), 0, + CAT->getSize().getZExtValue()); + if (!Result.hasArrayFiller()) return true; + + // Zero-initialize all elements. + LValue Subobject = This; + Subobject.addArray(Info, E, CAT); + ImplicitValueInitExpr VIE(CAT->getElementType()); + return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE); + } + + bool VisitInitListExpr(const InitListExpr *E); + bool VisitCXXConstructExpr(const CXXConstructExpr *E); + bool VisitCXXConstructExpr(const CXXConstructExpr *E, + const LValue &Subobject, + APValue *Value, QualType Type); + }; +} // end anonymous namespace + +static bool EvaluateArray(const Expr *E, const LValue &This, + APValue &Result, EvalInfo &Info) { + assert(E->isRValue() && E->getType()->isArrayType() && "not an array rvalue"); + return ArrayExprEvaluator(Info, This, Result).Visit(E); +} + +bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E) { + const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(E->getType()); + if (!CAT) + return Error(E); + + // C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...] + // an appropriately-typed string literal enclosed in braces. + if (E->isStringLiteralInit()) { + LValue LV; + if (!EvaluateLValue(E->getInit(0), LV, Info)) + return false; + APValue Val; + LV.moveInto(Val); + return Success(Val, E); + } + + bool Success = true; + + assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) && + "zero-initialized array shouldn't have any initialized elts"); + APValue Filler; + if (Result.isArray() && Result.hasArrayFiller()) + Filler = Result.getArrayFiller(); + + unsigned NumEltsToInit = E->getNumInits(); + unsigned NumElts = CAT->getSize().getZExtValue(); + const Expr *FillerExpr = E->hasArrayFiller() ? E->getArrayFiller() : nullptr; + + // If the initializer might depend on the array index, run it for each + // array element. For now, just whitelist non-class value-initialization. + if (NumEltsToInit != NumElts && !isa<ImplicitValueInitExpr>(FillerExpr)) + NumEltsToInit = NumElts; + + Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts); + + // If the array was previously zero-initialized, preserve the + // zero-initialized values. + if (!Filler.isUninit()) { + for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I) + Result.getArrayInitializedElt(I) = Filler; + if (Result.hasArrayFiller()) + Result.getArrayFiller() = Filler; + } + + LValue Subobject = This; + Subobject.addArray(Info, E, CAT); + for (unsigned Index = 0; Index != NumEltsToInit; ++Index) { + const Expr *Init = + Index < E->getNumInits() ? E->getInit(Index) : FillerExpr; + if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), + Info, Subobject, Init) || + !HandleLValueArrayAdjustment(Info, Init, Subobject, + CAT->getElementType(), 1)) { + if (!Info.keepEvaluatingAfterFailure()) + return false; + Success = false; + } + } + + if (!Result.hasArrayFiller()) + return Success; + + // If we get here, we have a trivial filler, which we can just evaluate + // once and splat over the rest of the array elements. + assert(FillerExpr && "no array filler for incomplete init list"); + return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, + FillerExpr) && Success; +} + +bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { + return VisitCXXConstructExpr(E, This, &Result, E->getType()); +} + +bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E, + const LValue &Subobject, + APValue *Value, + QualType Type) { + bool HadZeroInit = !Value->isUninit(); + + if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) { + unsigned N = CAT->getSize().getZExtValue(); + + // Preserve the array filler if we had prior zero-initialization. + APValue Filler = + HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller() + : APValue(); + + *Value = APValue(APValue::UninitArray(), N, N); + + if (HadZeroInit) + for (unsigned I = 0; I != N; ++I) + Value->getArrayInitializedElt(I) = Filler; + + // Initialize the elements. + LValue ArrayElt = Subobject; + ArrayElt.addArray(Info, E, CAT); + for (unsigned I = 0; I != N; ++I) + if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I), + CAT->getElementType()) || + !HandleLValueArrayAdjustment(Info, E, ArrayElt, + CAT->getElementType(), 1)) + return false; + + return true; + } + + if (!Type->isRecordType()) + return Error(E); + + const CXXConstructorDecl *FD = E->getConstructor(); + + bool ZeroInit = E->requiresZeroInitialization(); + if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { + if (HadZeroInit) + return true; + + // See RecordExprEvaluator::VisitCXXConstructExpr for explanation. + ImplicitValueInitExpr VIE(Type); + return EvaluateInPlace(*Value, Info, Subobject, &VIE); + } + + const FunctionDecl *Definition = nullptr; + FD->getBody(Definition); + + if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition)) + return false; + + if (ZeroInit && !HadZeroInit) { + ImplicitValueInitExpr VIE(Type); + if (!EvaluateInPlace(*Value, Info, Subobject, &VIE)) + return false; + } + + auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs()); + return HandleConstructorCall(E->getExprLoc(), Subobject, Args, + cast<CXXConstructorDecl>(Definition), + Info, *Value); +} + +//===----------------------------------------------------------------------===// +// Integer Evaluation +// +// As a GNU extension, we support casting pointers to sufficiently-wide integer +// types and back in constant folding. Integer values are thus represented +// either as an integer-valued APValue, or as an lvalue-valued APValue. +//===----------------------------------------------------------------------===// + +namespace { +class IntExprEvaluator + : public ExprEvaluatorBase<IntExprEvaluator> { + APValue &Result; +public: + IntExprEvaluator(EvalInfo &info, APValue &result) + : ExprEvaluatorBaseTy(info), Result(result) {} + + bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) { + assert(E->getType()->isIntegralOrEnumerationType() && + "Invalid evaluation result."); + assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() && + "Invalid evaluation result."); + assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && + "Invalid evaluation result."); + Result = APValue(SI); + return true; + } + bool Success(const llvm::APSInt &SI, const Expr *E) { + return Success(SI, E, Result); + } + + bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) { + assert(E->getType()->isIntegralOrEnumerationType() && + "Invalid evaluation result."); + assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && + "Invalid evaluation result."); + Result = APValue(APSInt(I)); + Result.getInt().setIsUnsigned( + E->getType()->isUnsignedIntegerOrEnumerationType()); + return true; + } + bool Success(const llvm::APInt &I, const Expr *E) { + return Success(I, E, Result); + } + + bool Success(uint64_t Value, const Expr *E, APValue &Result) { + assert(E->getType()->isIntegralOrEnumerationType() && + "Invalid evaluation result."); + Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType())); + return true; + } + bool Success(uint64_t Value, const Expr *E) { + return Success(Value, E, Result); + } + + bool Success(CharUnits Size, const Expr *E) { + return Success(Size.getQuantity(), E); + } + + bool Success(const APValue &V, const Expr *E) { + if (V.isLValue() || V.isAddrLabelDiff()) { + Result = V; + return true; + } + return Success(V.getInt(), E); + } + + bool ZeroInitialization(const Expr *E) { return Success(0, E); } + + //===--------------------------------------------------------------------===// + // Visitor Methods + //===--------------------------------------------------------------------===// + + bool VisitIntegerLiteral(const IntegerLiteral *E) { + return Success(E->getValue(), E); + } + bool VisitCharacterLiteral(const CharacterLiteral *E) { + return Success(E->getValue(), E); + } + + bool CheckReferencedDecl(const Expr *E, const Decl *D); + bool VisitDeclRefExpr(const DeclRefExpr *E) { + if (CheckReferencedDecl(E, E->getDecl())) + return true; + + return ExprEvaluatorBaseTy::VisitDeclRefExpr(E); + } + bool VisitMemberExpr(const MemberExpr *E) { + if (CheckReferencedDecl(E, E->getMemberDecl())) { + VisitIgnoredValue(E->getBase()); + return true; + } + + return ExprEvaluatorBaseTy::VisitMemberExpr(E); + } + + bool VisitCallExpr(const CallExpr *E); + bool VisitBinaryOperator(const BinaryOperator *E); + bool VisitOffsetOfExpr(const OffsetOfExpr *E); + bool VisitUnaryOperator(const UnaryOperator *E); + + bool VisitCastExpr(const CastExpr* E); + bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E); + + bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) { + return Success(E->getValue(), E); + } + + bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) { + return Success(E->getValue(), E); + } + + // Note, GNU defines __null as an integer, not a pointer. + bool VisitGNUNullExpr(const GNUNullExpr *E) { + return ZeroInitialization(E); + } + + bool VisitTypeTraitExpr(const TypeTraitExpr *E) { + return Success(E->getValue(), E); + } + + bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) { + return Success(E->getValue(), E); + } + + bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) { + return Success(E->getValue(), E); + } + + bool VisitUnaryReal(const UnaryOperator *E); + bool VisitUnaryImag(const UnaryOperator *E); + + bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E); + bool VisitSizeOfPackExpr(const SizeOfPackExpr *E); + +private: + static QualType GetObjectType(APValue::LValueBase B); + bool TryEvaluateBuiltinObjectSize(const CallExpr *E); + // FIXME: Missing: array subscript of vector, member of vector +}; +} // end anonymous namespace + +/// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and +/// produce either the integer value or a pointer. +/// +/// GCC has a heinous extension which folds casts between pointer types and +/// pointer-sized integral types. We support this by allowing the evaluation of +/// an integer rvalue to produce a pointer (represented as an lvalue) instead. +/// Some simple arithmetic on such values is supported (they are treated much +/// like char*). +static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, + EvalInfo &Info) { + assert(E->isRValue() && E->getType()->isIntegralOrEnumerationType()); + return IntExprEvaluator(Info, Result).Visit(E); +} + +static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) { + APValue Val; + if (!EvaluateIntegerOrLValue(E, Val, Info)) + return false; + if (!Val.isInt()) { + // FIXME: It would be better to produce the diagnostic for casting + // a pointer to an integer. + Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); + return false; + } + Result = Val.getInt(); + return true; +} + +/// Check whether the given declaration can be directly converted to an integral +/// rvalue. If not, no diagnostic is produced; there are other things we can +/// try. +bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) { + // Enums are integer constant exprs. + if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) { + // Check for signedness/width mismatches between E type and ECD value. + bool SameSign = (ECD->getInitVal().isSigned() + == E->getType()->isSignedIntegerOrEnumerationType()); + bool SameWidth = (ECD->getInitVal().getBitWidth() + == Info.Ctx.getIntWidth(E->getType())); + if (SameSign && SameWidth) + return Success(ECD->getInitVal(), E); + else { + // Get rid of mismatch (otherwise Success assertions will fail) + // by computing a new value matching the type of E. + llvm::APSInt Val = ECD->getInitVal(); + if (!SameSign) + Val.setIsSigned(!ECD->getInitVal().isSigned()); + if (!SameWidth) + Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType())); + return Success(Val, E); + } + } + return false; +} + +/// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way +/// as GCC. +static int EvaluateBuiltinClassifyType(const CallExpr *E) { + // The following enum mimics the values returned by GCC. + // FIXME: Does GCC differ between lvalue and rvalue references here? + enum gcc_type_class { + no_type_class = -1, + void_type_class, integer_type_class, char_type_class, + enumeral_type_class, boolean_type_class, + pointer_type_class, reference_type_class, offset_type_class, + real_type_class, complex_type_class, + function_type_class, method_type_class, + record_type_class, union_type_class, + array_type_class, string_type_class, + lang_type_class + }; + + // If no argument was supplied, default to "no_type_class". This isn't + // ideal, however it is what gcc does. + if (E->getNumArgs() == 0) + return no_type_class; + + QualType ArgTy = E->getArg(0)->getType(); + if (ArgTy->isVoidType()) + return void_type_class; + else if (ArgTy->isEnumeralType()) + return enumeral_type_class; + else if (ArgTy->isBooleanType()) + return boolean_type_class; + else if (ArgTy->isCharType()) + return string_type_class; // gcc doesn't appear to use char_type_class + else if (ArgTy->isIntegerType()) + return integer_type_class; + else if (ArgTy->isPointerType()) + return pointer_type_class; + else if (ArgTy->isReferenceType()) + return reference_type_class; + else if (ArgTy->isRealType()) + return real_type_class; + else if (ArgTy->isComplexType()) + return complex_type_class; + else if (ArgTy->isFunctionType()) + return function_type_class; + else if (ArgTy->isStructureOrClassType()) + return record_type_class; + else if (ArgTy->isUnionType()) + return union_type_class; + else if (ArgTy->isArrayType()) + return array_type_class; + else if (ArgTy->isUnionType()) + return union_type_class; + else // FIXME: offset_type_class, method_type_class, & lang_type_class? + llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type"); +} + +/// EvaluateBuiltinConstantPForLValue - Determine the result of +/// __builtin_constant_p when applied to the given lvalue. +/// +/// An lvalue is only "constant" if it is a pointer or reference to the first +/// character of a string literal. +template<typename LValue> +static bool EvaluateBuiltinConstantPForLValue(const LValue &LV) { + const Expr *E = LV.getLValueBase().template dyn_cast<const Expr*>(); + return E && isa<StringLiteral>(E) && LV.getLValueOffset().isZero(); +} + +/// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to +/// GCC as we can manage. +static bool EvaluateBuiltinConstantP(ASTContext &Ctx, const Expr *Arg) { + QualType ArgType = Arg->getType(); + + // __builtin_constant_p always has one operand. The rules which gcc follows + // are not precisely documented, but are as follows: + // + // - If the operand is of integral, floating, complex or enumeration type, + // and can be folded to a known value of that type, it returns 1. + // - If the operand and can be folded to a pointer to the first character + // of a string literal (or such a pointer cast to an integral type), it + // returns 1. + // + // Otherwise, it returns 0. + // + // FIXME: GCC also intends to return 1 for literals of aggregate types, but + // its support for this does not currently work. + if (ArgType->isIntegralOrEnumerationType()) { + Expr::EvalResult Result; + if (!Arg->EvaluateAsRValue(Result, Ctx) || Result.HasSideEffects) + return false; + + APValue &V = Result.Val; + if (V.getKind() == APValue::Int) + return true; + + return EvaluateBuiltinConstantPForLValue(V); + } else if (ArgType->isFloatingType() || ArgType->isAnyComplexType()) { + return Arg->isEvaluatable(Ctx); + } else if (ArgType->isPointerType() || Arg->isGLValue()) { + LValue LV; + Expr::EvalStatus Status; + EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold); + if ((Arg->isGLValue() ? EvaluateLValue(Arg, LV, Info) + : EvaluatePointer(Arg, LV, Info)) && + !Status.HasSideEffects) + return EvaluateBuiltinConstantPForLValue(LV); + } + + // Anything else isn't considered to be sufficiently constant. + return false; +} + +/// Retrieves the "underlying object type" of the given expression, +/// as used by __builtin_object_size. +QualType IntExprEvaluator::GetObjectType(APValue::LValueBase B) { + if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { + if (const VarDecl *VD = dyn_cast<VarDecl>(D)) + return VD->getType(); + } else if (const Expr *E = B.get<const Expr*>()) { + if (isa<CompoundLiteralExpr>(E)) + return E->getType(); + } + + return QualType(); +} + +bool IntExprEvaluator::TryEvaluateBuiltinObjectSize(const CallExpr *E) { + LValue Base; + + { + // The operand of __builtin_object_size is never evaluated for side-effects. + // If there are any, but we can determine the pointed-to object anyway, then + // ignore the side-effects. + SpeculativeEvaluationRAII SpeculativeEval(Info); + if (!EvaluatePointer(E->getArg(0), Base, Info)) + return false; + } + + if (!Base.getLValueBase()) { + // It is not possible to determine which objects ptr points to at compile time, + // __builtin_object_size should return (size_t) -1 for type 0 or 1 + // and (size_t) 0 for type 2 or 3. + llvm::APSInt TypeIntVaue; + const Expr *ExprType = E->getArg(1); + if (!ExprType->EvaluateAsInt(TypeIntVaue, Info.Ctx)) + return false; + if (TypeIntVaue == 0 || TypeIntVaue == 1) + return Success(-1, E); + if (TypeIntVaue == 2 || TypeIntVaue == 3) + return Success(0, E); + return Error(E); + } + + QualType T = GetObjectType(Base.getLValueBase()); + if (T.isNull() || + T->isIncompleteType() || + T->isFunctionType() || + T->isVariablyModifiedType() || + T->isDependentType()) + return Error(E); + + CharUnits Size = Info.Ctx.getTypeSizeInChars(T); + CharUnits Offset = Base.getLValueOffset(); + + if (!Offset.isNegative() && Offset <= Size) + Size -= Offset; + else + Size = CharUnits::Zero(); + return Success(Size, E); +} + +bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) { + switch (unsigned BuiltinOp = E->getBuiltinCallee()) { + default: + return ExprEvaluatorBaseTy::VisitCallExpr(E); + + case Builtin::BI__builtin_object_size: { + if (TryEvaluateBuiltinObjectSize(E)) + return true; + + // If evaluating the argument has side-effects, we can't determine the size + // of the object, and so we lower it to unknown now. CodeGen relies on us to + // handle all cases where the expression has side-effects. + if (E->getArg(0)->HasSideEffects(Info.Ctx)) { + if (E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue() <= 1) + return Success(-1ULL, E); + return Success(0, E); + } + + // Expression had no side effects, but we couldn't statically determine the + // size of the referenced object. + switch (Info.EvalMode) { + case EvalInfo::EM_ConstantExpression: + case EvalInfo::EM_PotentialConstantExpression: + case EvalInfo::EM_ConstantFold: + case EvalInfo::EM_EvaluateForOverflow: + case EvalInfo::EM_IgnoreSideEffects: + return Error(E); + case EvalInfo::EM_ConstantExpressionUnevaluated: + case EvalInfo::EM_PotentialConstantExpressionUnevaluated: + return Success(-1ULL, E); + } + } + + case Builtin::BI__builtin_bswap16: + case Builtin::BI__builtin_bswap32: + case Builtin::BI__builtin_bswap64: { + APSInt Val; + if (!EvaluateInteger(E->getArg(0), Val, Info)) + return false; + + return Success(Val.byteSwap(), E); + } + + case Builtin::BI__builtin_classify_type: + return Success(EvaluateBuiltinClassifyType(E), E); + + // FIXME: BI__builtin_clrsb + // FIXME: BI__builtin_clrsbl + // FIXME: BI__builtin_clrsbll + + case Builtin::BI__builtin_clz: + case Builtin::BI__builtin_clzl: + case Builtin::BI__builtin_clzll: + case Builtin::BI__builtin_clzs: { + APSInt Val; + if (!EvaluateInteger(E->getArg(0), Val, Info)) + return false; + if (!Val) + return Error(E); + + return Success(Val.countLeadingZeros(), E); + } + + case Builtin::BI__builtin_constant_p: + return Success(EvaluateBuiltinConstantP(Info.Ctx, E->getArg(0)), E); + + case Builtin::BI__builtin_ctz: + case Builtin::BI__builtin_ctzl: + case Builtin::BI__builtin_ctzll: + case Builtin::BI__builtin_ctzs: { + APSInt Val; + if (!EvaluateInteger(E->getArg(0), Val, Info)) + return false; + if (!Val) + return Error(E); + + return Success(Val.countTrailingZeros(), E); + } + + case Builtin::BI__builtin_eh_return_data_regno: { + int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); + Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand); + return Success(Operand, E); + } + + case Builtin::BI__builtin_expect: + return Visit(E->getArg(0)); + + case Builtin::BI__builtin_ffs: + case Builtin::BI__builtin_ffsl: + case Builtin::BI__builtin_ffsll: { + APSInt Val; + if (!EvaluateInteger(E->getArg(0), Val, Info)) + return false; + + unsigned N = Val.countTrailingZeros(); + return Success(N == Val.getBitWidth() ? 0 : N + 1, E); + } + + case Builtin::BI__builtin_fpclassify: { + APFloat Val(0.0); + if (!EvaluateFloat(E->getArg(5), Val, Info)) + return false; + unsigned Arg; + switch (Val.getCategory()) { + case APFloat::fcNaN: Arg = 0; break; + case APFloat::fcInfinity: Arg = 1; break; + case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break; + case APFloat::fcZero: Arg = 4; break; + } + return Visit(E->getArg(Arg)); + } + + case Builtin::BI__builtin_isinf_sign: { + APFloat Val(0.0); + return EvaluateFloat(E->getArg(0), Val, Info) && + Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E); + } + + case Builtin::BI__builtin_isinf: { + APFloat Val(0.0); + return EvaluateFloat(E->getArg(0), Val, Info) && + Success(Val.isInfinity() ? 1 : 0, E); + } + + case Builtin::BI__builtin_isfinite: { + APFloat Val(0.0); + return EvaluateFloat(E->getArg(0), Val, Info) && + Success(Val.isFinite() ? 1 : 0, E); + } + + case Builtin::BI__builtin_isnan: { + APFloat Val(0.0); + return EvaluateFloat(E->getArg(0), Val, Info) && + Success(Val.isNaN() ? 1 : 0, E); + } + + case Builtin::BI__builtin_isnormal: { + APFloat Val(0.0); + return EvaluateFloat(E->getArg(0), Val, Info) && + Success(Val.isNormal() ? 1 : 0, E); + } + + case Builtin::BI__builtin_parity: + case Builtin::BI__builtin_parityl: + case Builtin::BI__builtin_parityll: { + APSInt Val; + if (!EvaluateInteger(E->getArg(0), Val, Info)) + return false; + + return Success(Val.countPopulation() % 2, E); + } + + case Builtin::BI__builtin_popcount: + case Builtin::BI__builtin_popcountl: + case Builtin::BI__builtin_popcountll: { + APSInt Val; + if (!EvaluateInteger(E->getArg(0), Val, Info)) + return false; + + return Success(Val.countPopulation(), E); + } + + case Builtin::BIstrlen: + // A call to strlen is not a constant expression. + if (Info.getLangOpts().CPlusPlus11) + Info.CCEDiag(E, diag::note_constexpr_invalid_function) + << /*isConstexpr*/0 << /*isConstructor*/0 << "'strlen'"; + else + Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); + // Fall through. + case Builtin::BI__builtin_strlen: { + // As an extension, we support __builtin_strlen() as a constant expression, + // and support folding strlen() to a constant. + LValue String; + if (!EvaluatePointer(E->getArg(0), String, Info)) + return false; + + // Fast path: if it's a string literal, search the string value. + if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>( + String.getLValueBase().dyn_cast<const Expr *>())) { + // The string literal may have embedded null characters. Find the first + // one and truncate there. + StringRef Str = S->getBytes(); + int64_t Off = String.Offset.getQuantity(); + if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() && + S->getCharByteWidth() == 1) { + Str = Str.substr(Off); + + StringRef::size_type Pos = Str.find(0); + if (Pos != StringRef::npos) + Str = Str.substr(0, Pos); + + return Success(Str.size(), E); + } + + // Fall through to slow path to issue appropriate diagnostic. + } + + // Slow path: scan the bytes of the string looking for the terminating 0. + QualType CharTy = E->getArg(0)->getType()->getPointeeType(); + for (uint64_t Strlen = 0; /**/; ++Strlen) { + APValue Char; + if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) || + !Char.isInt()) + return false; + if (!Char.getInt()) + return Success(Strlen, E); + if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1)) + return false; + } + } + + case Builtin::BI__atomic_always_lock_free: + case Builtin::BI__atomic_is_lock_free: + case Builtin::BI__c11_atomic_is_lock_free: { + APSInt SizeVal; + if (!EvaluateInteger(E->getArg(0), SizeVal, Info)) + return false; + + // For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power + // of two less than the maximum inline atomic width, we know it is + // lock-free. If the size isn't a power of two, or greater than the + // maximum alignment where we promote atomics, we know it is not lock-free + // (at least not in the sense of atomic_is_lock_free). Otherwise, + // the answer can only be determined at runtime; for example, 16-byte + // atomics have lock-free implementations on some, but not all, + // x86-64 processors. + + // Check power-of-two. + CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue()); + if (Size.isPowerOfTwo()) { + // Check against inlining width. + unsigned InlineWidthBits = + Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth(); + if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) { + if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free || + Size == CharUnits::One() || + E->getArg(1)->isNullPointerConstant(Info.Ctx, + Expr::NPC_NeverValueDependent)) + // OK, we will inline appropriately-aligned operations of this size, + // and _Atomic(T) is appropriately-aligned. + return Success(1, E); + + QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()-> + castAs<PointerType>()->getPointeeType(); + if (!PointeeType->isIncompleteType() && + Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) { + // OK, we will inline operations on this object. + return Success(1, E); + } + } + } + + return BuiltinOp == Builtin::BI__atomic_always_lock_free ? + Success(0, E) : Error(E); + } + } +} + +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()) { + const Decl *ADecl = GetLValueBaseDecl(A); + if (!ADecl) + return false; + const Decl *BDecl = GetLValueBaseDecl(B); + if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl()) + return false; + } + + return IsGlobalLValue(A.getLValueBase()) || + A.getLValueCallIndex() == B.getLValueCallIndex(); +} + +/// \brief Determine whether this is a pointer past the end of the complete +/// object referred to by the lvalue. +static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx, + const LValue &LV) { + // A null pointer can be viewed as being "past the end" but we don't + // choose to look at it that way here. + if (!LV.getLValueBase()) + return false; + + // If the designator is valid and refers to a subobject, we're not pointing + // past the end. + if (!LV.getLValueDesignator().Invalid && + !LV.getLValueDesignator().isOnePastTheEnd()) + return false; + + // We're a past-the-end pointer if we point to the byte after the object, + // no matter what our type or path is. + auto Size = Ctx.getTypeSizeInChars(getType(LV.getLValueBase())); + return LV.getLValueOffset() == Size; +} + +namespace { + +/// \brief Data recursive integer evaluator of certain binary operators. +/// +/// We use a data recursive algorithm for binary operators so that we are able +/// to handle extreme cases of chained binary operators without causing stack +/// overflow. +class DataRecursiveIntBinOpEvaluator { + struct EvalResult { + APValue Val; + bool Failed; + + EvalResult() : Failed(false) { } + + void swap(EvalResult &RHS) { + Val.swap(RHS.Val); + Failed = RHS.Failed; + RHS.Failed = false; + } + }; + + struct Job { + const Expr *E; + EvalResult LHSResult; // meaningful only for binary operator expression. + enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind; + + Job() : StoredInfo(nullptr) {} + void startSpeculativeEval(EvalInfo &Info) { + OldEvalStatus = Info.EvalStatus; + Info.EvalStatus.Diag = nullptr; + StoredInfo = &Info; + } + ~Job() { + if (StoredInfo) { + StoredInfo->EvalStatus = OldEvalStatus; + } + } + private: + EvalInfo *StoredInfo; // non-null if status changed. + Expr::EvalStatus OldEvalStatus; + }; + + SmallVector<Job, 16> Queue; + + IntExprEvaluator &IntEval; + EvalInfo &Info; + APValue &FinalResult; + +public: + DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result) + : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { } + + /// \brief True if \param E is a binary operator that we are going to handle + /// data recursively. + /// We handle binary operators that are comma, logical, or that have operands + /// with integral or enumeration type. + static bool shouldEnqueue(const BinaryOperator *E) { + return E->getOpcode() == BO_Comma || + E->isLogicalOp() || + (E->getLHS()->getType()->isIntegralOrEnumerationType() && + E->getRHS()->getType()->isIntegralOrEnumerationType()); + } + + bool Traverse(const BinaryOperator *E) { + enqueue(E); + EvalResult PrevResult; + while (!Queue.empty()) + process(PrevResult); + + if (PrevResult.Failed) return false; + + FinalResult.swap(PrevResult.Val); + return true; + } + +private: + bool Success(uint64_t Value, const Expr *E, APValue &Result) { + return IntEval.Success(Value, E, Result); + } + bool Success(const APSInt &Value, const Expr *E, APValue &Result) { + return IntEval.Success(Value, E, Result); + } + bool Error(const Expr *E) { + return IntEval.Error(E); + } + bool Error(const Expr *E, diag::kind D) { + return IntEval.Error(E, D); + } + + OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { + return Info.CCEDiag(E, D); + } + + // \brief Returns true if visiting the RHS is necessary, false otherwise. + bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, + bool &SuppressRHSDiags); + + bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, + const BinaryOperator *E, APValue &Result); + + void EvaluateExpr(const Expr *E, EvalResult &Result) { + Result.Failed = !Evaluate(Result.Val, Info, E); + if (Result.Failed) + Result.Val = APValue(); + } + + void process(EvalResult &Result); + + void enqueue(const Expr *E) { + E = E->IgnoreParens(); + Queue.resize(Queue.size()+1); + Queue.back().E = E; + Queue.back().Kind = Job::AnyExprKind; + } +}; + +} + +bool DataRecursiveIntBinOpEvaluator:: + VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, + bool &SuppressRHSDiags) { + if (E->getOpcode() == BO_Comma) { + // Ignore LHS but note if we could not evaluate it. + if (LHSResult.Failed) + return Info.noteSideEffect(); + return true; + } + + if (E->isLogicalOp()) { + bool LHSAsBool; + if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) { + // We were able to evaluate the LHS, see if we can get away with not + // evaluating the RHS: 0 && X -> 0, 1 || X -> 1 + if (LHSAsBool == (E->getOpcode() == BO_LOr)) { + Success(LHSAsBool, E, LHSResult.Val); + return false; // Ignore RHS + } + } else { + LHSResult.Failed = true; + + // Since we weren't able to evaluate the left hand side, it + // must have had side effects. + if (!Info.noteSideEffect()) + return false; + + // We can't evaluate the LHS; however, sometimes the result + // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. + // Don't ignore RHS and suppress diagnostics from this arm. + SuppressRHSDiags = true; + } + + return true; + } + + assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && + E->getRHS()->getType()->isIntegralOrEnumerationType()); + + if (LHSResult.Failed && !Info.keepEvaluatingAfterFailure()) + return false; // Ignore RHS; + + return true; +} + +bool DataRecursiveIntBinOpEvaluator:: + VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, + const BinaryOperator *E, APValue &Result) { + if (E->getOpcode() == BO_Comma) { + if (RHSResult.Failed) + return false; + Result = RHSResult.Val; + return true; + } + + if (E->isLogicalOp()) { + bool lhsResult, rhsResult; + bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult); + bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult); + + if (LHSIsOK) { + if (RHSIsOK) { + if (E->getOpcode() == BO_LOr) + return Success(lhsResult || rhsResult, E, Result); + else + return Success(lhsResult && rhsResult, E, Result); + } + } else { + if (RHSIsOK) { + // We can't evaluate the LHS; however, sometimes the result + // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. + if (rhsResult == (E->getOpcode() == BO_LOr)) + return Success(rhsResult, E, Result); + } + } + + return false; + } + + assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && + E->getRHS()->getType()->isIntegralOrEnumerationType()); + + if (LHSResult.Failed || RHSResult.Failed) + return false; + + const APValue &LHSVal = LHSResult.Val; + const APValue &RHSVal = RHSResult.Val; + + // Handle cases like (unsigned long)&a + 4. + if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) { + Result = LHSVal; + CharUnits AdditionalOffset = + CharUnits::fromQuantity(RHSVal.getInt().getZExtValue()); + if (E->getOpcode() == BO_Add) + Result.getLValueOffset() += AdditionalOffset; + else + Result.getLValueOffset() -= AdditionalOffset; + return true; + } + + // Handle cases like 4 + (unsigned long)&a + if (E->getOpcode() == BO_Add && + RHSVal.isLValue() && LHSVal.isInt()) { + Result = RHSVal; + Result.getLValueOffset() += + CharUnits::fromQuantity(LHSVal.getInt().getZExtValue()); + return true; + } + + if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) { + // Handle (intptr_t)&&A - (intptr_t)&&B. + if (!LHSVal.getLValueOffset().isZero() || + !RHSVal.getLValueOffset().isZero()) + return false; + const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>(); + const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>(); + if (!LHSExpr || !RHSExpr) + return false; + const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); + const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); + if (!LHSAddrExpr || !RHSAddrExpr) + return false; + // Make sure both labels come from the same function. + if (LHSAddrExpr->getLabel()->getDeclContext() != + RHSAddrExpr->getLabel()->getDeclContext()) + return false; + Result = APValue(LHSAddrExpr, RHSAddrExpr); + return true; + } + + // All the remaining cases expect both operands to be an integer + if (!LHSVal.isInt() || !RHSVal.isInt()) + return Error(E); + + // Set up the width and signedness manually, in case it can't be deduced + // from the operation we're performing. + // FIXME: Don't do this in the cases where we can deduce it. + APSInt Value(Info.Ctx.getIntWidth(E->getType()), + E->getType()->isUnsignedIntegerOrEnumerationType()); + if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(), + RHSVal.getInt(), Value)) + return false; + return Success(Value, E, Result); +} + +void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) { + Job &job = Queue.back(); + + switch (job.Kind) { + case Job::AnyExprKind: { + if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) { + if (shouldEnqueue(Bop)) { + job.Kind = Job::BinOpKind; + enqueue(Bop->getLHS()); + return; + } + } + + EvaluateExpr(job.E, Result); + Queue.pop_back(); + return; + } + + case Job::BinOpKind: { + const BinaryOperator *Bop = cast<BinaryOperator>(job.E); + bool SuppressRHSDiags = false; + if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) { + Queue.pop_back(); + return; + } + if (SuppressRHSDiags) + job.startSpeculativeEval(Info); + job.LHSResult.swap(Result); + job.Kind = Job::BinOpVisitedLHSKind; + enqueue(Bop->getRHS()); + return; + } + + case Job::BinOpVisitedLHSKind: { + const BinaryOperator *Bop = cast<BinaryOperator>(job.E); + EvalResult RHS; + RHS.swap(Result); + Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val); + Queue.pop_back(); + return; + } + } + + llvm_unreachable("Invalid Job::Kind!"); +} + +bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { + if (!Info.keepEvaluatingAfterFailure() && E->isAssignmentOp()) + return Error(E); + + if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E)) + return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E); + + QualType LHSTy = E->getLHS()->getType(); + QualType RHSTy = E->getRHS()->getType(); + + if (LHSTy->isAnyComplexType() || RHSTy->isAnyComplexType()) { + ComplexValue LHS, RHS; + bool LHSOK; + if (E->isAssignmentOp()) { + LValue LV; + EvaluateLValue(E->getLHS(), LV, Info); + LHSOK = false; + } else if (LHSTy->isRealFloatingType()) { + LHSOK = EvaluateFloat(E->getLHS(), LHS.FloatReal, Info); + if (LHSOK) { + LHS.makeComplexFloat(); + LHS.FloatImag = APFloat(LHS.FloatReal.getSemantics()); + } + } else { + LHSOK = EvaluateComplex(E->getLHS(), LHS, Info); + } + if (!LHSOK && !Info.keepEvaluatingAfterFailure()) + return false; + + if (E->getRHS()->getType()->isRealFloatingType()) { + if (!EvaluateFloat(E->getRHS(), RHS.FloatReal, Info) || !LHSOK) + return false; + RHS.makeComplexFloat(); + RHS.FloatImag = APFloat(RHS.FloatReal.getSemantics()); + } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) + return false; + + if (LHS.isComplexFloat()) { + APFloat::cmpResult CR_r = + LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal()); + APFloat::cmpResult CR_i = + LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag()); + + if (E->getOpcode() == BO_EQ) + return Success((CR_r == APFloat::cmpEqual && + CR_i == APFloat::cmpEqual), E); + else { + assert(E->getOpcode() == BO_NE && + "Invalid complex comparison."); + return Success(((CR_r == APFloat::cmpGreaterThan || + CR_r == APFloat::cmpLessThan || + CR_r == APFloat::cmpUnordered) || + (CR_i == APFloat::cmpGreaterThan || + CR_i == APFloat::cmpLessThan || + CR_i == APFloat::cmpUnordered)), E); + } + } else { + if (E->getOpcode() == BO_EQ) + return Success((LHS.getComplexIntReal() == RHS.getComplexIntReal() && + LHS.getComplexIntImag() == RHS.getComplexIntImag()), E); + else { + assert(E->getOpcode() == BO_NE && + "Invalid compex comparison."); + return Success((LHS.getComplexIntReal() != RHS.getComplexIntReal() || + LHS.getComplexIntImag() != RHS.getComplexIntImag()), E); + } + } + } + + if (LHSTy->isRealFloatingType() && + RHSTy->isRealFloatingType()) { + APFloat RHS(0.0), LHS(0.0); + + bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info); + if (!LHSOK && !Info.keepEvaluatingAfterFailure()) + return false; + + if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK) + return false; + + APFloat::cmpResult CR = LHS.compare(RHS); + + switch (E->getOpcode()) { + default: + llvm_unreachable("Invalid binary operator!"); + case BO_LT: + return Success(CR == APFloat::cmpLessThan, E); + case BO_GT: + return Success(CR == APFloat::cmpGreaterThan, E); + case BO_LE: + return Success(CR == APFloat::cmpLessThan || CR == APFloat::cmpEqual, E); + case BO_GE: + return Success(CR == APFloat::cmpGreaterThan || CR == APFloat::cmpEqual, + E); + case BO_EQ: + return Success(CR == APFloat::cmpEqual, E); + case BO_NE: + return Success(CR == APFloat::cmpGreaterThan + || CR == APFloat::cmpLessThan + || CR == APFloat::cmpUnordered, E); + } + } + + if (LHSTy->isPointerType() && RHSTy->isPointerType()) { + if (E->getOpcode() == BO_Sub || E->isComparisonOp()) { + LValue LHSValue, RHSValue; + + bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); + if (!LHSOK && Info.keepEvaluatingAfterFailure()) + return false; + + if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK) + return false; + + // Reject differing bases from the normal codepath; we special-case + // comparisons to null. + if (!HasSameBase(LHSValue, RHSValue)) { + if (E->getOpcode() == BO_Sub) { + // Handle &&A - &&B. + if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero()) + return false; + const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr*>(); + const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr*>(); + if (!LHSExpr || !RHSExpr) + return false; + const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); + const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); + if (!LHSAddrExpr || !RHSAddrExpr) + return false; + // Make sure both labels come from the same function. + if (LHSAddrExpr->getLabel()->getDeclContext() != + RHSAddrExpr->getLabel()->getDeclContext()) + return false; + Result = APValue(LHSAddrExpr, RHSAddrExpr); + return true; + } + // Inequalities and subtractions between unrelated pointers have + // unspecified or undefined behavior. + if (!E->isEqualityOp()) + return Error(E); + // A constant address may compare equal to the address of a symbol. + // The one exception is that address of an object cannot compare equal + // to a null pointer constant. + if ((!LHSValue.Base && !LHSValue.Offset.isZero()) || + (!RHSValue.Base && !RHSValue.Offset.isZero())) + return Error(E); + // It's implementation-defined whether distinct literals will have + // distinct addresses. In clang, the result of such a comparison is + // unspecified, so it is not a constant expression. However, we do know + // that the address of a literal will be non-null. + if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) && + LHSValue.Base && RHSValue.Base) + return Error(E); + // We can't tell whether weak symbols will end up pointing to the same + // object. + if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue)) + return Error(E); + // We can't compare the address of the start of one object with the + // past-the-end address of another object, per C++ DR1652. + if ((LHSValue.Base && LHSValue.Offset.isZero() && + isOnePastTheEndOfCompleteObject(Info.Ctx, RHSValue)) || + (RHSValue.Base && RHSValue.Offset.isZero() && + isOnePastTheEndOfCompleteObject(Info.Ctx, LHSValue))) + return Error(E); + // We can't tell whether an object is at the same address as another + // zero sized object. + if ((RHSValue.Base && isZeroSized(LHSValue)) || + (LHSValue.Base && isZeroSized(RHSValue))) + return Error(E); + // Pointers with different bases cannot represent the same object. + // (Note that clang defaults to -fmerge-all-constants, which can + // lead to inconsistent results for comparisons involving the address + // of a constant; this generally doesn't matter in practice.) + return Success(E->getOpcode() == BO_NE, E); + } + + const CharUnits &LHSOffset = LHSValue.getLValueOffset(); + const CharUnits &RHSOffset = RHSValue.getLValueOffset(); + + SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); + SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); + + if (E->getOpcode() == BO_Sub) { + // C++11 [expr.add]p6: + // Unless both pointers point to elements of the same array object, or + // one past the last element of the array object, the behavior is + // undefined. + if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && + !AreElementsOfSameArray(getType(LHSValue.Base), + LHSDesignator, RHSDesignator)) + CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array); + + QualType Type = E->getLHS()->getType(); + QualType ElementType = Type->getAs<PointerType>()->getPointeeType(); + + CharUnits ElementSize; + if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize)) + return false; + + // As an extension, a type may have zero size (empty struct or union in + // C, array of zero length). Pointer subtraction in such cases has + // undefined behavior, so is not constant. + if (ElementSize.isZero()) { + Info.Diag(E, diag::note_constexpr_pointer_subtraction_zero_size) + << ElementType; + return false; + } + + // FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime, + // and produce incorrect results when it overflows. Such behavior + // appears to be non-conforming, but is common, so perhaps we should + // assume the standard intended for such cases to be undefined behavior + // and check for them. + + // Compute (LHSOffset - RHSOffset) / Size carefully, checking for + // overflow in the final conversion to ptrdiff_t. + APSInt LHS( + llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false); + APSInt RHS( + llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false); + APSInt ElemSize( + llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true), false); + APSInt TrueResult = (LHS - RHS) / ElemSize; + APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType())); + + if (Result.extend(65) != TrueResult) + HandleOverflow(Info, E, TrueResult, E->getType()); + return Success(Result, E); + } + + // C++11 [expr.rel]p3: + // Pointers to void (after pointer conversions) can be compared, with a + // result defined as follows: If both pointers represent the same + // address or are both the null pointer value, the result is true if the + // operator is <= or >= and false otherwise; otherwise the result is + // unspecified. + // We interpret this as applying to pointers to *cv* void. + if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && + E->isRelationalOp()) + CCEDiag(E, diag::note_constexpr_void_comparison); + + // C++11 [expr.rel]p2: + // - If two pointers point to non-static data members of the same object, + // or to subobjects or array elements fo such members, recursively, the + // pointer to the later declared member compares greater provided the + // two members have the same access control and provided their class is + // not a union. + // [...] + // - Otherwise pointer comparisons are unspecified. + if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && + E->isRelationalOp()) { + bool WasArrayIndex; + unsigned Mismatch = + FindDesignatorMismatch(getType(LHSValue.Base), LHSDesignator, + RHSDesignator, WasArrayIndex); + // At the point where the designators diverge, the comparison has a + // specified value if: + // - we are comparing array indices + // - we are comparing fields of a union, or fields with the same access + // Otherwise, the result is unspecified and thus the comparison is not a + // constant expression. + if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() && + Mismatch < RHSDesignator.Entries.size()) { + const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]); + const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]); + if (!LF && !RF) + CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes); + else if (!LF) + CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) + << getAsBaseClass(LHSDesignator.Entries[Mismatch]) + << RF->getParent() << RF; + else if (!RF) + CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) + << getAsBaseClass(RHSDesignator.Entries[Mismatch]) + << LF->getParent() << LF; + else if (!LF->getParent()->isUnion() && + LF->getAccess() != RF->getAccess()) + CCEDiag(E, diag::note_constexpr_pointer_comparison_differing_access) + << LF << LF->getAccess() << RF << RF->getAccess() + << LF->getParent(); + } + } + + // The comparison here must be unsigned, and performed with the same + // width as the pointer. + unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy); + uint64_t CompareLHS = LHSOffset.getQuantity(); + uint64_t CompareRHS = RHSOffset.getQuantity(); + assert(PtrSize <= 64 && "Unexpected pointer width"); + uint64_t Mask = ~0ULL >> (64 - PtrSize); + CompareLHS &= Mask; + CompareRHS &= Mask; + + // If there is a base and this is a relational operator, we can only + // compare pointers within the object in question; otherwise, the result + // depends on where the object is located in memory. + if (!LHSValue.Base.isNull() && E->isRelationalOp()) { + QualType BaseTy = getType(LHSValue.Base); + if (BaseTy->isIncompleteType()) + return Error(E); + CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy); + uint64_t OffsetLimit = Size.getQuantity(); + if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit) + return Error(E); + } + + switch (E->getOpcode()) { + default: llvm_unreachable("missing comparison operator"); + case BO_LT: return Success(CompareLHS < CompareRHS, E); + case BO_GT: return Success(CompareLHS > CompareRHS, E); + case BO_LE: return Success(CompareLHS <= CompareRHS, E); + case BO_GE: return Success(CompareLHS >= CompareRHS, E); + case BO_EQ: return Success(CompareLHS == CompareRHS, E); + case BO_NE: return Success(CompareLHS != CompareRHS, E); + } + } + } + + if (LHSTy->isMemberPointerType()) { + assert(E->isEqualityOp() && "unexpected member pointer operation"); + assert(RHSTy->isMemberPointerType() && "invalid comparison"); + + MemberPtr LHSValue, RHSValue; + + bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info); + if (!LHSOK && Info.keepEvaluatingAfterFailure()) + return false; + + if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK) + return false; + + // C++11 [expr.eq]p2: + // If both operands are null, they compare equal. Otherwise if only one is + // null, they compare unequal. + if (!LHSValue.getDecl() || !RHSValue.getDecl()) { + bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl(); + return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E); + } + + // Otherwise if either is a pointer to a virtual member function, the + // result is unspecified. + if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl())) + if (MD->isVirtual()) + CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; + if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl())) + if (MD->isVirtual()) + CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; + + // Otherwise they compare equal if and only if they would refer to the + // same member of the same most derived object or the same subobject if + // they were dereferenced with a hypothetical object of the associated + // class type. + bool Equal = LHSValue == RHSValue; + return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E); + } + + if (LHSTy->isNullPtrType()) { + assert(E->isComparisonOp() && "unexpected nullptr operation"); + assert(RHSTy->isNullPtrType() && "missing pointer conversion"); + // C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t + // are compared, the result is true of the operator is <=, >= or ==, and + // false otherwise. + BinaryOperator::Opcode Opcode = E->getOpcode(); + return Success(Opcode == BO_EQ || Opcode == BO_LE || Opcode == BO_GE, E); + } + + assert((!LHSTy->isIntegralOrEnumerationType() || + !RHSTy->isIntegralOrEnumerationType()) && + "DataRecursiveIntBinOpEvaluator should have handled integral types"); + // We can't continue from here for non-integral types. + return ExprEvaluatorBaseTy::VisitBinaryOperator(E); +} + +/// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with +/// a result as the expression's type. +bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr( + const UnaryExprOrTypeTraitExpr *E) { + switch(E->getKind()) { + case UETT_AlignOf: { + if (E->isArgumentType()) + return Success(GetAlignOfType(Info, E->getArgumentType()), E); + else + return Success(GetAlignOfExpr(Info, E->getArgumentExpr()), E); + } + + case UETT_VecStep: { + QualType Ty = E->getTypeOfArgument(); + + if (Ty->isVectorType()) { + unsigned n = Ty->castAs<VectorType>()->getNumElements(); + + // The vec_step built-in functions that take a 3-component + // vector return 4. (OpenCL 1.1 spec 6.11.12) + if (n == 3) + n = 4; + + return Success(n, E); + } else + return Success(1, E); + } + + case UETT_SizeOf: { + QualType SrcTy = E->getTypeOfArgument(); + // C++ [expr.sizeof]p2: "When applied to a reference or a reference type, + // the result is the size of the referenced type." + if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>()) + SrcTy = Ref->getPointeeType(); + + CharUnits Sizeof; + if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof)) + return false; + return Success(Sizeof, E); + } + } + + llvm_unreachable("unknown expr/type trait"); +} + +bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) { + CharUnits Result; + unsigned n = OOE->getNumComponents(); + if (n == 0) + return Error(OOE); + QualType CurrentType = OOE->getTypeSourceInfo()->getType(); + for (unsigned i = 0; i != n; ++i) { + OffsetOfExpr::OffsetOfNode ON = OOE->getComponent(i); + switch (ON.getKind()) { + case OffsetOfExpr::OffsetOfNode::Array: { + const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex()); + APSInt IdxResult; + if (!EvaluateInteger(Idx, IdxResult, Info)) + return false; + const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType); + if (!AT) + return Error(OOE); + CurrentType = AT->getElementType(); + CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType); + Result += IdxResult.getSExtValue() * ElementSize; + break; + } + + case OffsetOfExpr::OffsetOfNode::Field: { + FieldDecl *MemberDecl = ON.getField(); + const RecordType *RT = CurrentType->getAs<RecordType>(); + if (!RT) + return Error(OOE); + RecordDecl *RD = RT->getDecl(); + if (RD->isInvalidDecl()) return false; + const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); + unsigned i = MemberDecl->getFieldIndex(); + assert(i < RL.getFieldCount() && "offsetof field in wrong type"); + Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i)); + CurrentType = MemberDecl->getType().getNonReferenceType(); + break; + } + + case OffsetOfExpr::OffsetOfNode::Identifier: + llvm_unreachable("dependent __builtin_offsetof"); + + case OffsetOfExpr::OffsetOfNode::Base: { + CXXBaseSpecifier *BaseSpec = ON.getBase(); + if (BaseSpec->isVirtual()) + return Error(OOE); + + // Find the layout of the class whose base we are looking into. + const RecordType *RT = CurrentType->getAs<RecordType>(); + if (!RT) + return Error(OOE); + RecordDecl *RD = RT->getDecl(); + if (RD->isInvalidDecl()) return false; + const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); + + // Find the base class itself. + CurrentType = BaseSpec->getType(); + const RecordType *BaseRT = CurrentType->getAs<RecordType>(); + if (!BaseRT) + return Error(OOE); + + // Add the offset to the base. + Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl())); + break; + } + } + } + return Success(Result, OOE); +} + +bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { + switch (E->getOpcode()) { + default: + // Address, indirect, pre/post inc/dec, etc are not valid constant exprs. + // See C99 6.6p3. + return Error(E); + case UO_Extension: + // FIXME: Should extension allow i-c-e extension expressions in its scope? + // If so, we could clear the diagnostic ID. + return Visit(E->getSubExpr()); + case UO_Plus: + // The result is just the value. + return Visit(E->getSubExpr()); + case UO_Minus: { + if (!Visit(E->getSubExpr())) + return false; + if (!Result.isInt()) return Error(E); + const APSInt &Value = Result.getInt(); + if (Value.isSigned() && Value.isMinSignedValue()) + HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1), + E->getType()); + return Success(-Value, E); + } + case UO_Not: { + if (!Visit(E->getSubExpr())) + return false; + if (!Result.isInt()) return Error(E); + return Success(~Result.getInt(), E); + } + case UO_LNot: { + bool bres; + if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info)) + return false; + return Success(!bres, E); + } + } +} + +/// HandleCast - This is used to evaluate implicit or explicit casts where the +/// result type is integer. +bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) { + const Expr *SubExpr = E->getSubExpr(); + QualType DestType = E->getType(); + QualType SrcType = SubExpr->getType(); + + switch (E->getCastKind()) { + case CK_BaseToDerived: + case CK_DerivedToBase: + case CK_UncheckedDerivedToBase: + case CK_Dynamic: + case CK_ToUnion: + case CK_ArrayToPointerDecay: + case CK_FunctionToPointerDecay: + case CK_NullToPointer: + case CK_NullToMemberPointer: + case CK_BaseToDerivedMemberPointer: + case CK_DerivedToBaseMemberPointer: + case CK_ReinterpretMemberPointer: + case CK_ConstructorConversion: + case CK_IntegralToPointer: + case CK_ToVoid: + case CK_VectorSplat: + case CK_IntegralToFloating: + case CK_FloatingCast: + case CK_CPointerToObjCPointerCast: + case CK_BlockPointerToObjCPointerCast: + case CK_AnyPointerToBlockPointerCast: + case CK_ObjCObjectLValueCast: + case CK_FloatingRealToComplex: + case CK_FloatingComplexToReal: + case CK_FloatingComplexCast: + case CK_FloatingComplexToIntegralComplex: + case CK_IntegralRealToComplex: + case CK_IntegralComplexCast: + case CK_IntegralComplexToFloatingComplex: + case CK_BuiltinFnToFnPtr: + case CK_ZeroToOCLEvent: + case CK_NonAtomicToAtomic: + case CK_AddressSpaceConversion: + llvm_unreachable("invalid cast kind for integral value"); + + case CK_BitCast: + case CK_Dependent: + case CK_LValueBitCast: + case CK_ARCProduceObject: + case CK_ARCConsumeObject: + case CK_ARCReclaimReturnedObject: + case CK_ARCExtendBlockObject: + case CK_CopyAndAutoreleaseBlockObject: + return Error(E); + + case CK_UserDefinedConversion: + case CK_LValueToRValue: + case CK_AtomicToNonAtomic: + case CK_NoOp: + return ExprEvaluatorBaseTy::VisitCastExpr(E); + + case CK_MemberPointerToBoolean: + case CK_PointerToBoolean: + case CK_IntegralToBoolean: + case CK_FloatingToBoolean: + case CK_FloatingComplexToBoolean: + case CK_IntegralComplexToBoolean: { + bool BoolResult; + if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info)) + return false; + return Success(BoolResult, E); + } + + case CK_IntegralCast: { + if (!Visit(SubExpr)) + return false; + + if (!Result.isInt()) { + // Allow casts of address-of-label differences if they are no-ops + // or narrowing. (The narrowing case isn't actually guaranteed to + // be constant-evaluatable except in some narrow cases which are hard + // to detect here. We let it through on the assumption the user knows + // what they are doing.) + if (Result.isAddrLabelDiff()) + return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType); + // Only allow casts of lvalues if they are lossless. + return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType); + } + + return Success(HandleIntToIntCast(Info, E, DestType, SrcType, + Result.getInt()), E); + } + + case CK_PointerToIntegral: { + CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; + + LValue LV; + if (!EvaluatePointer(SubExpr, LV, Info)) + return false; + + if (LV.getLValueBase()) { + // Only allow based lvalue casts if they are lossless. + // FIXME: Allow a larger integer size than the pointer size, and allow + // narrowing back down to pointer width in subsequent integral casts. + // FIXME: Check integer type's active bits, not its type size. + if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType)) + return Error(E); + + LV.Designator.setInvalid(); + LV.moveInto(Result); + return true; + } + + APSInt AsInt = Info.Ctx.MakeIntValue(LV.getLValueOffset().getQuantity(), + SrcType); + return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E); + } + + case CK_IntegralComplexToReal: { + ComplexValue C; + if (!EvaluateComplex(SubExpr, C, Info)) + return false; + return Success(C.getComplexIntReal(), E); + } + + case CK_FloatingToIntegral: { + APFloat F(0.0); + if (!EvaluateFloat(SubExpr, F, Info)) + return false; + + APSInt Value; + if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value)) + return false; + return Success(Value, E); + } + } + + llvm_unreachable("unknown cast resulting in integral value"); +} + +bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { + if (E->getSubExpr()->getType()->isAnyComplexType()) { + ComplexValue LV; + if (!EvaluateComplex(E->getSubExpr(), LV, Info)) + return false; + if (!LV.isComplexInt()) + return Error(E); + return Success(LV.getComplexIntReal(), E); + } + + return Visit(E->getSubExpr()); +} + +bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { + if (E->getSubExpr()->getType()->isComplexIntegerType()) { + ComplexValue LV; + if (!EvaluateComplex(E->getSubExpr(), LV, Info)) + return false; + if (!LV.isComplexInt()) + return Error(E); + return Success(LV.getComplexIntImag(), E); + } + + VisitIgnoredValue(E->getSubExpr()); + return Success(0, E); +} + +bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) { + return Success(E->getPackLength(), E); +} + +bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) { + return Success(E->getValue(), E); +} + +//===----------------------------------------------------------------------===// +// Float Evaluation +//===----------------------------------------------------------------------===// + +namespace { +class FloatExprEvaluator + : public ExprEvaluatorBase<FloatExprEvaluator> { + APFloat &Result; +public: + FloatExprEvaluator(EvalInfo &info, APFloat &result) + : ExprEvaluatorBaseTy(info), Result(result) {} + + bool Success(const APValue &V, const Expr *e) { + Result = V.getFloat(); + return true; + } + + bool ZeroInitialization(const Expr *E) { + Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType())); + return true; + } + + bool VisitCallExpr(const CallExpr *E); + + bool VisitUnaryOperator(const UnaryOperator *E); + bool VisitBinaryOperator(const BinaryOperator *E); + bool VisitFloatingLiteral(const FloatingLiteral *E); + bool VisitCastExpr(const CastExpr *E); + + bool VisitUnaryReal(const UnaryOperator *E); + bool VisitUnaryImag(const UnaryOperator *E); + + // FIXME: Missing: array subscript of vector, member of vector +}; +} // end anonymous namespace + +static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) { + assert(E->isRValue() && E->getType()->isRealFloatingType()); + return FloatExprEvaluator(Info, Result).Visit(E); +} + +static bool TryEvaluateBuiltinNaN(const ASTContext &Context, + QualType ResultTy, + const Expr *Arg, + bool SNaN, + llvm::APFloat &Result) { + const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts()); + if (!S) return false; + + const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy); + + llvm::APInt fill; + + // Treat empty strings as if they were zero. + if (S->getString().empty()) + fill = llvm::APInt(32, 0); + else if (S->getString().getAsInteger(0, fill)) + return false; + + if (Context.getTargetInfo().isNan2008()) { + if (SNaN) + Result = llvm::APFloat::getSNaN(Sem, false, &fill); + else + Result = llvm::APFloat::getQNaN(Sem, false, &fill); + } else { + // Prior to IEEE 754-2008, architectures were allowed to choose whether + // the first bit of their significand was set for qNaN or sNaN. MIPS chose + // a different encoding to what became a standard in 2008, and for pre- + // 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as + // sNaN. This is now known as "legacy NaN" encoding. + if (SNaN) + Result = llvm::APFloat::getQNaN(Sem, false, &fill); + else + Result = llvm::APFloat::getSNaN(Sem, false, &fill); + } + + return true; +} + +bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) { + switch (E->getBuiltinCallee()) { + default: + return ExprEvaluatorBaseTy::VisitCallExpr(E); + + case Builtin::BI__builtin_huge_val: + case Builtin::BI__builtin_huge_valf: + case Builtin::BI__builtin_huge_vall: + case Builtin::BI__builtin_inf: + case Builtin::BI__builtin_inff: + case Builtin::BI__builtin_infl: { + const llvm::fltSemantics &Sem = + Info.Ctx.getFloatTypeSemantics(E->getType()); + Result = llvm::APFloat::getInf(Sem); + return true; + } + + case Builtin::BI__builtin_nans: + case Builtin::BI__builtin_nansf: + case Builtin::BI__builtin_nansl: + if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), + true, Result)) + return Error(E); + return true; + + case Builtin::BI__builtin_nan: + case Builtin::BI__builtin_nanf: + case Builtin::BI__builtin_nanl: + // If this is __builtin_nan() turn this into a nan, otherwise we + // can't constant fold it. + if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), + false, Result)) + return Error(E); + return true; + + case Builtin::BI__builtin_fabs: + case Builtin::BI__builtin_fabsf: + case Builtin::BI__builtin_fabsl: + if (!EvaluateFloat(E->getArg(0), Result, Info)) + return false; + + if (Result.isNegative()) + Result.changeSign(); + return true; + + // FIXME: Builtin::BI__builtin_powi + // FIXME: Builtin::BI__builtin_powif + // FIXME: Builtin::BI__builtin_powil + + case Builtin::BI__builtin_copysign: + case Builtin::BI__builtin_copysignf: + case Builtin::BI__builtin_copysignl: { + APFloat RHS(0.); + if (!EvaluateFloat(E->getArg(0), Result, Info) || + !EvaluateFloat(E->getArg(1), RHS, Info)) + return false; + Result.copySign(RHS); + return true; + } + } +} + +bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { + if (E->getSubExpr()->getType()->isAnyComplexType()) { + ComplexValue CV; + if (!EvaluateComplex(E->getSubExpr(), CV, Info)) + return false; + Result = CV.FloatReal; + return true; + } + + return Visit(E->getSubExpr()); +} + +bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { + if (E->getSubExpr()->getType()->isAnyComplexType()) { + ComplexValue CV; + if (!EvaluateComplex(E->getSubExpr(), CV, Info)) + return false; + Result = CV.FloatImag; + return true; + } + + VisitIgnoredValue(E->getSubExpr()); + const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType()); + Result = llvm::APFloat::getZero(Sem); + return true; +} + +bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { + switch (E->getOpcode()) { + default: return Error(E); + case UO_Plus: + return EvaluateFloat(E->getSubExpr(), Result, Info); + case UO_Minus: + if (!EvaluateFloat(E->getSubExpr(), Result, Info)) + return false; + Result.changeSign(); + return true; + } +} + +bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { + if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) + return ExprEvaluatorBaseTy::VisitBinaryOperator(E); + + APFloat RHS(0.0); + bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info); + if (!LHSOK && !Info.keepEvaluatingAfterFailure()) + return false; + return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK && + handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS); +} + +bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) { + Result = E->getValue(); + return true; +} + +bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) { + const Expr* SubExpr = E->getSubExpr(); + + switch (E->getCastKind()) { + default: + return ExprEvaluatorBaseTy::VisitCastExpr(E); + + case CK_IntegralToFloating: { + APSInt IntResult; + return EvaluateInteger(SubExpr, IntResult, Info) && + HandleIntToFloatCast(Info, E, SubExpr->getType(), IntResult, + E->getType(), Result); + } + + case CK_FloatingCast: { + if (!Visit(SubExpr)) + return false; + return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(), + Result); + } + + case CK_FloatingComplexToReal: { + ComplexValue V; + if (!EvaluateComplex(SubExpr, V, Info)) + return false; + Result = V.getComplexFloatReal(); + return true; + } + } +} + +//===----------------------------------------------------------------------===// +// Complex Evaluation (for float and integer) +//===----------------------------------------------------------------------===// + +namespace { +class ComplexExprEvaluator + : public ExprEvaluatorBase<ComplexExprEvaluator> { + ComplexValue &Result; + +public: + ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result) + : ExprEvaluatorBaseTy(info), Result(Result) {} + + bool Success(const APValue &V, const Expr *e) { + Result.setFrom(V); + return true; + } + + bool ZeroInitialization(const Expr *E); + + //===--------------------------------------------------------------------===// + // Visitor Methods + //===--------------------------------------------------------------------===// + + bool VisitImaginaryLiteral(const ImaginaryLiteral *E); + bool VisitCastExpr(const CastExpr *E); + bool VisitBinaryOperator(const BinaryOperator *E); + bool VisitUnaryOperator(const UnaryOperator *E); + bool VisitInitListExpr(const InitListExpr *E); +}; +} // end anonymous namespace + +static bool EvaluateComplex(const Expr *E, ComplexValue &Result, + EvalInfo &Info) { + assert(E->isRValue() && E->getType()->isAnyComplexType()); + return ComplexExprEvaluator(Info, Result).Visit(E); +} + +bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) { + QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType(); + if (ElemTy->isRealFloatingType()) { + Result.makeComplexFloat(); + APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy)); + Result.FloatReal = Zero; + Result.FloatImag = Zero; + } else { + Result.makeComplexInt(); + APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy); + Result.IntReal = Zero; + Result.IntImag = Zero; + } + return true; +} + +bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) { + const Expr* SubExpr = E->getSubExpr(); + + if (SubExpr->getType()->isRealFloatingType()) { + Result.makeComplexFloat(); + APFloat &Imag = Result.FloatImag; + if (!EvaluateFloat(SubExpr, Imag, Info)) + return false; + + Result.FloatReal = APFloat(Imag.getSemantics()); + return true; + } else { + assert(SubExpr->getType()->isIntegerType() && + "Unexpected imaginary literal."); + + Result.makeComplexInt(); + APSInt &Imag = Result.IntImag; + if (!EvaluateInteger(SubExpr, Imag, Info)) + return false; + + Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned()); + return true; + } +} + +bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) { + + switch (E->getCastKind()) { + case CK_BitCast: + case CK_BaseToDerived: + case CK_DerivedToBase: + case CK_UncheckedDerivedToBase: + case CK_Dynamic: + case CK_ToUnion: + case CK_ArrayToPointerDecay: + case CK_FunctionToPointerDecay: + case CK_NullToPointer: + case CK_NullToMemberPointer: + case CK_BaseToDerivedMemberPointer: + case CK_DerivedToBaseMemberPointer: + case CK_MemberPointerToBoolean: + case CK_ReinterpretMemberPointer: + case CK_ConstructorConversion: + case CK_IntegralToPointer: + case CK_PointerToIntegral: + case CK_PointerToBoolean: + case CK_ToVoid: + case CK_VectorSplat: + case CK_IntegralCast: + case CK_IntegralToBoolean: + case CK_IntegralToFloating: + case CK_FloatingToIntegral: + case CK_FloatingToBoolean: + case CK_FloatingCast: + case CK_CPointerToObjCPointerCast: + case CK_BlockPointerToObjCPointerCast: + case CK_AnyPointerToBlockPointerCast: + case CK_ObjCObjectLValueCast: + case CK_FloatingComplexToReal: + case CK_FloatingComplexToBoolean: + case CK_IntegralComplexToReal: + case CK_IntegralComplexToBoolean: + case CK_ARCProduceObject: + case CK_ARCConsumeObject: + case CK_ARCReclaimReturnedObject: + case CK_ARCExtendBlockObject: + case CK_CopyAndAutoreleaseBlockObject: + case CK_BuiltinFnToFnPtr: + case CK_ZeroToOCLEvent: + case CK_NonAtomicToAtomic: + case CK_AddressSpaceConversion: + llvm_unreachable("invalid cast kind for complex value"); + + case CK_LValueToRValue: + case CK_AtomicToNonAtomic: + case CK_NoOp: + return ExprEvaluatorBaseTy::VisitCastExpr(E); + + case CK_Dependent: + case CK_LValueBitCast: + case CK_UserDefinedConversion: + return Error(E); + + case CK_FloatingRealToComplex: { + APFloat &Real = Result.FloatReal; + if (!EvaluateFloat(E->getSubExpr(), Real, Info)) + return false; + + Result.makeComplexFloat(); + Result.FloatImag = APFloat(Real.getSemantics()); + return true; + } + + case CK_FloatingComplexCast: { + if (!Visit(E->getSubExpr())) + return false; + + QualType To = E->getType()->getAs<ComplexType>()->getElementType(); + QualType From + = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); + + return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) && + HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag); + } + + case CK_FloatingComplexToIntegralComplex: { + if (!Visit(E->getSubExpr())) + return false; + + QualType To = E->getType()->getAs<ComplexType>()->getElementType(); + QualType From + = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); + Result.makeComplexInt(); + return HandleFloatToIntCast(Info, E, From, Result.FloatReal, + To, Result.IntReal) && + HandleFloatToIntCast(Info, E, From, Result.FloatImag, + To, Result.IntImag); + } + + case CK_IntegralRealToComplex: { + APSInt &Real = Result.IntReal; + if (!EvaluateInteger(E->getSubExpr(), Real, Info)) + return false; + + Result.makeComplexInt(); + Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned()); + return true; + } + + case CK_IntegralComplexCast: { + if (!Visit(E->getSubExpr())) + return false; + + QualType To = E->getType()->getAs<ComplexType>()->getElementType(); + QualType From + = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); + + Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal); + Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag); + return true; + } + + case CK_IntegralComplexToFloatingComplex: { + if (!Visit(E->getSubExpr())) + return false; + + QualType To = E->getType()->castAs<ComplexType>()->getElementType(); + QualType From + = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType(); + Result.makeComplexFloat(); + return HandleIntToFloatCast(Info, E, From, Result.IntReal, + To, Result.FloatReal) && + HandleIntToFloatCast(Info, E, From, Result.IntImag, + To, Result.FloatImag); + } + } + + llvm_unreachable("unknown cast resulting in complex value"); +} + +bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { + if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) + return ExprEvaluatorBaseTy::VisitBinaryOperator(E); + + // Track whether the LHS or RHS is real at the type system level. When this is + // the case we can simplify our evaluation strategy. + bool LHSReal = false, RHSReal = false; + + bool LHSOK; + if (E->getLHS()->getType()->isRealFloatingType()) { + LHSReal = true; + APFloat &Real = Result.FloatReal; + LHSOK = EvaluateFloat(E->getLHS(), Real, Info); + if (LHSOK) { + Result.makeComplexFloat(); + Result.FloatImag = APFloat(Real.getSemantics()); + } + } else { + LHSOK = Visit(E->getLHS()); + } + if (!LHSOK && !Info.keepEvaluatingAfterFailure()) + return false; + + ComplexValue RHS; + if (E->getRHS()->getType()->isRealFloatingType()) { + RHSReal = true; + APFloat &Real = RHS.FloatReal; + if (!EvaluateFloat(E->getRHS(), Real, Info) || !LHSOK) + return false; + RHS.makeComplexFloat(); + RHS.FloatImag = APFloat(Real.getSemantics()); + } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) + return false; + + assert(!(LHSReal && RHSReal) && + "Cannot have both operands of a complex operation be real."); + switch (E->getOpcode()) { + default: return Error(E); + case BO_Add: + if (Result.isComplexFloat()) { + Result.getComplexFloatReal().add(RHS.getComplexFloatReal(), + APFloat::rmNearestTiesToEven); + if (LHSReal) + Result.getComplexFloatImag() = RHS.getComplexFloatImag(); + else if (!RHSReal) + Result.getComplexFloatImag().add(RHS.getComplexFloatImag(), + APFloat::rmNearestTiesToEven); + } else { + Result.getComplexIntReal() += RHS.getComplexIntReal(); + Result.getComplexIntImag() += RHS.getComplexIntImag(); + } + break; + case BO_Sub: + if (Result.isComplexFloat()) { + Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(), + APFloat::rmNearestTiesToEven); + if (LHSReal) { + Result.getComplexFloatImag() = RHS.getComplexFloatImag(); + Result.getComplexFloatImag().changeSign(); + } else if (!RHSReal) { + Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(), + APFloat::rmNearestTiesToEven); + } + } else { + Result.getComplexIntReal() -= RHS.getComplexIntReal(); + Result.getComplexIntImag() -= RHS.getComplexIntImag(); + } + break; + case BO_Mul: + if (Result.isComplexFloat()) { + // This is an implementation of complex multiplication according to the + // constraints laid out in C11 Annex G. The implemantion uses the + // following naming scheme: + // (a + ib) * (c + id) + ComplexValue LHS = Result; + APFloat &A = LHS.getComplexFloatReal(); + APFloat &B = LHS.getComplexFloatImag(); + APFloat &C = RHS.getComplexFloatReal(); + APFloat &D = RHS.getComplexFloatImag(); + APFloat &ResR = Result.getComplexFloatReal(); + APFloat &ResI = Result.getComplexFloatImag(); + if (LHSReal) { + assert(!RHSReal && "Cannot have two real operands for a complex op!"); + ResR = A * C; + ResI = A * D; + } else if (RHSReal) { + ResR = C * A; + ResI = C * B; + } else { + // In the fully general case, we need to handle NaNs and infinities + // robustly. + APFloat AC = A * C; + APFloat BD = B * D; + APFloat AD = A * D; + APFloat BC = B * C; + ResR = AC - BD; + ResI = AD + BC; + if (ResR.isNaN() && ResI.isNaN()) { + bool Recalc = false; + if (A.isInfinity() || B.isInfinity()) { + A = APFloat::copySign( + APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A); + B = APFloat::copySign( + APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B); + if (C.isNaN()) + C = APFloat::copySign(APFloat(C.getSemantics()), C); + if (D.isNaN()) + D = APFloat::copySign(APFloat(D.getSemantics()), D); + Recalc = true; + } + if (C.isInfinity() || D.isInfinity()) { + C = APFloat::copySign( + APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C); + D = APFloat::copySign( + APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D); + if (A.isNaN()) + A = APFloat::copySign(APFloat(A.getSemantics()), A); + if (B.isNaN()) + B = APFloat::copySign(APFloat(B.getSemantics()), B); + Recalc = true; + } + if (!Recalc && (AC.isInfinity() || BD.isInfinity() || + AD.isInfinity() || BC.isInfinity())) { + if (A.isNaN()) + A = APFloat::copySign(APFloat(A.getSemantics()), A); + if (B.isNaN()) + B = APFloat::copySign(APFloat(B.getSemantics()), B); + if (C.isNaN()) + C = APFloat::copySign(APFloat(C.getSemantics()), C); + if (D.isNaN()) + D = APFloat::copySign(APFloat(D.getSemantics()), D); + Recalc = true; + } + if (Recalc) { + ResR = APFloat::getInf(A.getSemantics()) * (A * C - B * D); + ResI = APFloat::getInf(A.getSemantics()) * (A * D + B * C); + } + } + } + } else { + ComplexValue LHS = Result; + Result.getComplexIntReal() = + (LHS.getComplexIntReal() * RHS.getComplexIntReal() - + LHS.getComplexIntImag() * RHS.getComplexIntImag()); + Result.getComplexIntImag() = + (LHS.getComplexIntReal() * RHS.getComplexIntImag() + + LHS.getComplexIntImag() * RHS.getComplexIntReal()); + } + break; + case BO_Div: + if (Result.isComplexFloat()) { + // This is an implementation of complex division according to the + // constraints laid out in C11 Annex G. The implemantion uses the + // following naming scheme: + // (a + ib) / (c + id) + ComplexValue LHS = Result; + APFloat &A = LHS.getComplexFloatReal(); + APFloat &B = LHS.getComplexFloatImag(); + APFloat &C = RHS.getComplexFloatReal(); + APFloat &D = RHS.getComplexFloatImag(); + APFloat &ResR = Result.getComplexFloatReal(); + APFloat &ResI = Result.getComplexFloatImag(); + if (RHSReal) { + ResR = A / C; + ResI = B / C; + } else { + if (LHSReal) { + // No real optimizations we can do here, stub out with zero. + B = APFloat::getZero(A.getSemantics()); + } + int DenomLogB = 0; + APFloat MaxCD = maxnum(abs(C), abs(D)); + if (MaxCD.isFinite()) { + DenomLogB = ilogb(MaxCD); + C = scalbn(C, -DenomLogB); + D = scalbn(D, -DenomLogB); + } + APFloat Denom = C * C + D * D; + ResR = scalbn((A * C + B * D) / Denom, -DenomLogB); + ResI = scalbn((B * C - A * D) / Denom, -DenomLogB); + if (ResR.isNaN() && ResI.isNaN()) { + if (Denom.isPosZero() && (!A.isNaN() || !B.isNaN())) { + ResR = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * A; + ResI = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * B; + } else if ((A.isInfinity() || B.isInfinity()) && C.isFinite() && + D.isFinite()) { + A = APFloat::copySign( + APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A); + B = APFloat::copySign( + APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B); + ResR = APFloat::getInf(ResR.getSemantics()) * (A * C + B * D); + ResI = APFloat::getInf(ResI.getSemantics()) * (B * C - A * D); + } else if (MaxCD.isInfinity() && A.isFinite() && B.isFinite()) { + C = APFloat::copySign( + APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C); + D = APFloat::copySign( + APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D); + ResR = APFloat::getZero(ResR.getSemantics()) * (A * C + B * D); + ResI = APFloat::getZero(ResI.getSemantics()) * (B * C - A * D); + } + } + } + } else { + if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0) + return Error(E, diag::note_expr_divide_by_zero); + + ComplexValue LHS = Result; + APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() + + RHS.getComplexIntImag() * RHS.getComplexIntImag(); + Result.getComplexIntReal() = + (LHS.getComplexIntReal() * RHS.getComplexIntReal() + + LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den; + Result.getComplexIntImag() = + (LHS.getComplexIntImag() * RHS.getComplexIntReal() - + LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den; + } + break; + } + + return true; +} + +bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { + // Get the operand value into 'Result'. + if (!Visit(E->getSubExpr())) + return false; + + switch (E->getOpcode()) { + default: + return Error(E); + case UO_Extension: + return true; + case UO_Plus: + // The result is always just the subexpr. + return true; + case UO_Minus: + if (Result.isComplexFloat()) { + Result.getComplexFloatReal().changeSign(); + Result.getComplexFloatImag().changeSign(); + } + else { + Result.getComplexIntReal() = -Result.getComplexIntReal(); + Result.getComplexIntImag() = -Result.getComplexIntImag(); + } + return true; + case UO_Not: + if (Result.isComplexFloat()) + Result.getComplexFloatImag().changeSign(); + else + Result.getComplexIntImag() = -Result.getComplexIntImag(); + return true; + } +} + +bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) { + if (E->getNumInits() == 2) { + if (E->getType()->isComplexType()) { + Result.makeComplexFloat(); + if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info)) + return false; + if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info)) + return false; + } else { + Result.makeComplexInt(); + if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info)) + return false; + if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info)) + return false; + } + return true; + } + return ExprEvaluatorBaseTy::VisitInitListExpr(E); +} + +//===----------------------------------------------------------------------===// +// Atomic expression evaluation, essentially just handling the NonAtomicToAtomic +// implicit conversion. +//===----------------------------------------------------------------------===// + +namespace { +class AtomicExprEvaluator : + public ExprEvaluatorBase<AtomicExprEvaluator> { + APValue &Result; +public: + AtomicExprEvaluator(EvalInfo &Info, APValue &Result) + : ExprEvaluatorBaseTy(Info), Result(Result) {} + + bool Success(const APValue &V, const Expr *E) { + Result = V; + return true; + } + + bool ZeroInitialization(const Expr *E) { + ImplicitValueInitExpr VIE( + E->getType()->castAs<AtomicType>()->getValueType()); + return Evaluate(Result, Info, &VIE); + } + + bool VisitCastExpr(const CastExpr *E) { + switch (E->getCastKind()) { + default: + return ExprEvaluatorBaseTy::VisitCastExpr(E); + case CK_NonAtomicToAtomic: + return Evaluate(Result, Info, E->getSubExpr()); + } + } +}; +} // end anonymous namespace + +static bool EvaluateAtomic(const Expr *E, APValue &Result, EvalInfo &Info) { + assert(E->isRValue() && E->getType()->isAtomicType()); + return AtomicExprEvaluator(Info, Result).Visit(E); +} + +//===----------------------------------------------------------------------===// +// Void expression evaluation, primarily for a cast to void on the LHS of a +// comma operator +//===----------------------------------------------------------------------===// + +namespace { +class VoidExprEvaluator + : public ExprEvaluatorBase<VoidExprEvaluator> { +public: + VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {} + + bool Success(const APValue &V, const Expr *e) { return true; } + + bool VisitCastExpr(const CastExpr *E) { + switch (E->getCastKind()) { + default: + return ExprEvaluatorBaseTy::VisitCastExpr(E); + case CK_ToVoid: + VisitIgnoredValue(E->getSubExpr()); + return true; + } + } + + bool VisitCallExpr(const CallExpr *E) { + switch (E->getBuiltinCallee()) { + default: + return ExprEvaluatorBaseTy::VisitCallExpr(E); + case Builtin::BI__assume: + case Builtin::BI__builtin_assume: + // The argument is not evaluated! + return true; + } + } +}; +} // end anonymous namespace + +static bool EvaluateVoid(const Expr *E, EvalInfo &Info) { + assert(E->isRValue() && E->getType()->isVoidType()); + return VoidExprEvaluator(Info).Visit(E); +} + +//===----------------------------------------------------------------------===// +// Top level Expr::EvaluateAsRValue method. +//===----------------------------------------------------------------------===// + +static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) { + // In C, function designators are not lvalues, but we evaluate them as if they + // are. + QualType T = E->getType(); + if (E->isGLValue() || T->isFunctionType()) { + LValue LV; + if (!EvaluateLValue(E, LV, Info)) + return false; + LV.moveInto(Result); + } else if (T->isVectorType()) { + if (!EvaluateVector(E, Result, Info)) + return false; + } else if (T->isIntegralOrEnumerationType()) { + if (!IntExprEvaluator(Info, Result).Visit(E)) + return false; + } else if (T->hasPointerRepresentation()) { + LValue LV; + if (!EvaluatePointer(E, LV, Info)) + return false; + LV.moveInto(Result); + } else if (T->isRealFloatingType()) { + llvm::APFloat F(0.0); + if (!EvaluateFloat(E, F, Info)) + return false; + Result = APValue(F); + } else if (T->isAnyComplexType()) { + ComplexValue C; + if (!EvaluateComplex(E, C, Info)) + return false; + C.moveInto(Result); + } else if (T->isMemberPointerType()) { + MemberPtr P; + if (!EvaluateMemberPointer(E, P, Info)) + return false; + P.moveInto(Result); + return true; + } else if (T->isArrayType()) { + LValue LV; + LV.set(E, Info.CurrentCall->Index); + APValue &Value = Info.CurrentCall->createTemporary(E, false); + if (!EvaluateArray(E, LV, Value, Info)) + return false; + Result = Value; + } else if (T->isRecordType()) { + LValue LV; + LV.set(E, Info.CurrentCall->Index); + APValue &Value = Info.CurrentCall->createTemporary(E, false); + if (!EvaluateRecord(E, LV, Value, Info)) + return false; + Result = Value; + } else if (T->isVoidType()) { + if (!Info.getLangOpts().CPlusPlus11) + Info.CCEDiag(E, diag::note_constexpr_nonliteral) + << E->getType(); + if (!EvaluateVoid(E, Info)) + return false; + } else if (T->isAtomicType()) { + if (!EvaluateAtomic(E, Result, Info)) + return false; + } else if (Info.getLangOpts().CPlusPlus11) { + Info.Diag(E, diag::note_constexpr_nonliteral) << E->getType(); + return false; + } else { + Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); + return false; + } + + return true; +} + +/// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some +/// cases, the in-place evaluation is essential, since later initializers for +/// an object can indirectly refer to subobjects which were initialized earlier. +static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This, + const Expr *E, bool AllowNonLiteralTypes) { + assert(!E->isValueDependent()); + + if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This)) + return false; + + if (E->isRValue()) { + // Evaluate arrays and record types in-place, so that later initializers can + // refer to earlier-initialized members of the object. + if (E->getType()->isArrayType()) + return EvaluateArray(E, This, Result, Info); + else if (E->getType()->isRecordType()) + return EvaluateRecord(E, This, Result, Info); + } + + // For any other type, in-place evaluation is unimportant. + return Evaluate(Result, Info, E); +} + +/// EvaluateAsRValue - Try to evaluate this expression, performing an implicit +/// lvalue-to-rvalue cast if it is an lvalue. +static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) { + if (E->getType().isNull()) + return false; + + if (!CheckLiteralType(Info, E)) + return false; + + if (!::Evaluate(Result, Info, E)) + return false; + + if (E->isGLValue()) { + LValue LV; + LV.setFrom(Info.Ctx, Result); + if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result)) + return false; + } + + // Check this core constant expression is a constant expression. + return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result); +} + +static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result, + const ASTContext &Ctx, bool &IsConst) { + // Fast-path evaluations of integer literals, since we sometimes see files + // containing vast quantities of these. + if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) { + Result.Val = APValue(APSInt(L->getValue(), + L->getType()->isUnsignedIntegerType())); + IsConst = true; + return true; + } + + // This case should be rare, but we need to check it before we check on + // the type below. + if (Exp->getType().isNull()) { + IsConst = false; + return true; + } + + // FIXME: Evaluating values of large array and record types can cause + // performance problems. Only do so in C++11 for now. + if (Exp->isRValue() && (Exp->getType()->isArrayType() || + Exp->getType()->isRecordType()) && + !Ctx.getLangOpts().CPlusPlus11) { + IsConst = false; + return true; + } + return false; +} + + +/// EvaluateAsRValue - Return true if this is a constant which we can fold using +/// any crazy technique (that has nothing to do with language standards) that +/// we want to. If this function returns true, it returns the folded constant +/// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion +/// will be applied to the result. +bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx) const { + bool IsConst; + if (FastEvaluateAsRValue(this, Result, Ctx, IsConst)) + return IsConst; + + EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); + return ::EvaluateAsRValue(Info, this, Result.Val); +} + +bool Expr::EvaluateAsBooleanCondition(bool &Result, + const ASTContext &Ctx) const { + EvalResult Scratch; + return EvaluateAsRValue(Scratch, Ctx) && + HandleConversionToBool(Scratch.Val, Result); +} + +bool Expr::EvaluateAsInt(APSInt &Result, const ASTContext &Ctx, + SideEffectsKind AllowSideEffects) const { + if (!getType()->isIntegralOrEnumerationType()) + return false; + + EvalResult ExprResult; + if (!EvaluateAsRValue(ExprResult, Ctx) || !ExprResult.Val.isInt() || + (!AllowSideEffects && ExprResult.HasSideEffects)) + return false; + + Result = ExprResult.Val.getInt(); + return true; +} + +bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx) const { + EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold); + + LValue LV; + if (!EvaluateLValue(this, LV, Info) || Result.HasSideEffects || + !CheckLValueConstantExpression(Info, getExprLoc(), + Ctx.getLValueReferenceType(getType()), LV)) + return false; + + LV.moveInto(Result.Val); + return true; +} + +bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx, + const VarDecl *VD, + SmallVectorImpl<PartialDiagnosticAt> &Notes) const { + // FIXME: Evaluating initializers for large array and record types can cause + // performance problems. Only do so in C++11 for now. + if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) && + !Ctx.getLangOpts().CPlusPlus11) + return false; + + Expr::EvalStatus EStatus; + EStatus.Diag = &Notes; + + EvalInfo InitInfo(Ctx, EStatus, EvalInfo::EM_ConstantFold); + InitInfo.setEvaluatingDecl(VD, Value); + + LValue LVal; + LVal.set(VD); + + // C++11 [basic.start.init]p2: + // Variables with static storage duration or thread storage duration shall be + // zero-initialized before any other initialization takes place. + // This behavior is not present in C. + if (Ctx.getLangOpts().CPlusPlus && !VD->hasLocalStorage() && + !VD->getType()->isReferenceType()) { + ImplicitValueInitExpr VIE(VD->getType()); + if (!EvaluateInPlace(Value, InitInfo, LVal, &VIE, + /*AllowNonLiteralTypes=*/true)) + return false; + } + + if (!EvaluateInPlace(Value, InitInfo, LVal, this, + /*AllowNonLiteralTypes=*/true) || + EStatus.HasSideEffects) + return false; + + return CheckConstantExpression(InitInfo, VD->getLocation(), VD->getType(), + Value); +} + +/// isEvaluatable - Call EvaluateAsRValue to see if this expression can be +/// constant folded, but discard the result. +bool Expr::isEvaluatable(const ASTContext &Ctx) const { + EvalResult Result; + return EvaluateAsRValue(Result, Ctx) && !Result.HasSideEffects; +} + +APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx, + SmallVectorImpl<PartialDiagnosticAt> *Diag) const { + EvalResult EvalResult; + EvalResult.Diag = Diag; + bool Result = EvaluateAsRValue(EvalResult, Ctx); + (void)Result; + assert(Result && "Could not evaluate expression"); + assert(EvalResult.Val.isInt() && "Expression did not evaluate to integer"); + + return EvalResult.Val.getInt(); +} + +void Expr::EvaluateForOverflow(const ASTContext &Ctx) const { + bool IsConst; + EvalResult EvalResult; + if (!FastEvaluateAsRValue(this, EvalResult, Ctx, IsConst)) { + EvalInfo Info(Ctx, EvalResult, EvalInfo::EM_EvaluateForOverflow); + (void)::EvaluateAsRValue(Info, this, EvalResult.Val); + } +} + +bool Expr::EvalResult::isGlobalLValue() const { + assert(Val.isLValue()); + return IsGlobalLValue(Val.getLValueBase()); +} + + +/// isIntegerConstantExpr - this recursive routine will test if an expression is +/// an integer constant expression. + +/// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero, +/// comma, etc + +// CheckICE - This function does the fundamental ICE checking: the returned +// ICEDiag contains an ICEKind indicating whether the expression is an ICE, +// and a (possibly null) SourceLocation indicating the location of the problem. +// +// Note that to reduce code duplication, this helper does no evaluation +// itself; the caller checks whether the expression is evaluatable, and +// in the rare cases where CheckICE actually cares about the evaluated +// value, it calls into Evalute. + +namespace { + +enum ICEKind { + /// This expression is an ICE. + IK_ICE, + /// This expression is not an ICE, but if it isn't evaluated, it's + /// a legal subexpression for an ICE. This return value is used to handle + /// the comma operator in C99 mode, and non-constant subexpressions. + IK_ICEIfUnevaluated, + /// This expression is not an ICE, and is not a legal subexpression for one. + IK_NotICE +}; + +struct ICEDiag { + ICEKind Kind; + SourceLocation Loc; + + ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {} +}; + +} + +static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); } + +static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; } + +static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) { + Expr::EvalResult EVResult; + if (!E->EvaluateAsRValue(EVResult, Ctx) || EVResult.HasSideEffects || + !EVResult.Val.isInt()) + return ICEDiag(IK_NotICE, E->getLocStart()); + + return NoDiag(); +} + +static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) { + assert(!E->isValueDependent() && "Should not see value dependent exprs!"); + if (!E->getType()->isIntegralOrEnumerationType()) + return ICEDiag(IK_NotICE, E->getLocStart()); + + switch (E->getStmtClass()) { +#define ABSTRACT_STMT(Node) +#define STMT(Node, Base) case Expr::Node##Class: +#define EXPR(Node, Base) +#include "clang/AST/StmtNodes.inc" + case Expr::PredefinedExprClass: + case Expr::FloatingLiteralClass: + case Expr::ImaginaryLiteralClass: + case Expr::StringLiteralClass: + case Expr::ArraySubscriptExprClass: + case Expr::MemberExprClass: + case Expr::CompoundAssignOperatorClass: + case Expr::CompoundLiteralExprClass: + case Expr::ExtVectorElementExprClass: + case Expr::DesignatedInitExprClass: + case Expr::ImplicitValueInitExprClass: + case Expr::ParenListExprClass: + case Expr::VAArgExprClass: + case Expr::AddrLabelExprClass: + case Expr::StmtExprClass: + case Expr::CXXMemberCallExprClass: + case Expr::CUDAKernelCallExprClass: + case Expr::CXXDynamicCastExprClass: + case Expr::CXXTypeidExprClass: + case Expr::CXXUuidofExprClass: + case Expr::MSPropertyRefExprClass: + case Expr::CXXNullPtrLiteralExprClass: + case Expr::UserDefinedLiteralClass: + case Expr::CXXThisExprClass: + case Expr::CXXThrowExprClass: + case Expr::CXXNewExprClass: + case Expr::CXXDeleteExprClass: + case Expr::CXXPseudoDestructorExprClass: + case Expr::UnresolvedLookupExprClass: + case Expr::TypoExprClass: + case Expr::DependentScopeDeclRefExprClass: + case Expr::CXXConstructExprClass: + case Expr::CXXStdInitializerListExprClass: + case Expr::CXXBindTemporaryExprClass: + case Expr::ExprWithCleanupsClass: + case Expr::CXXTemporaryObjectExprClass: + case Expr::CXXUnresolvedConstructExprClass: + case Expr::CXXDependentScopeMemberExprClass: + case Expr::UnresolvedMemberExprClass: + case Expr::ObjCStringLiteralClass: + case Expr::ObjCBoxedExprClass: + case Expr::ObjCArrayLiteralClass: + case Expr::ObjCDictionaryLiteralClass: + case Expr::ObjCEncodeExprClass: + case Expr::ObjCMessageExprClass: + case Expr::ObjCSelectorExprClass: + case Expr::ObjCProtocolExprClass: + case Expr::ObjCIvarRefExprClass: + case Expr::ObjCPropertyRefExprClass: + case Expr::ObjCSubscriptRefExprClass: + case Expr::ObjCIsaExprClass: + case Expr::ShuffleVectorExprClass: + case Expr::ConvertVectorExprClass: + case Expr::BlockExprClass: + case Expr::NoStmtClass: + case Expr::OpaqueValueExprClass: + case Expr::PackExpansionExprClass: + case Expr::SubstNonTypeTemplateParmPackExprClass: + case Expr::FunctionParmPackExprClass: + case Expr::AsTypeExprClass: + case Expr::ObjCIndirectCopyRestoreExprClass: + case Expr::MaterializeTemporaryExprClass: + case Expr::PseudoObjectExprClass: + case Expr::AtomicExprClass: + case Expr::LambdaExprClass: + case Expr::CXXFoldExprClass: + return ICEDiag(IK_NotICE, E->getLocStart()); + + case Expr::InitListExprClass: { + // C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the + // form "T x = { a };" is equivalent to "T x = a;". + // Unless we're initializing a reference, T is a scalar as it is known to be + // of integral or enumeration type. + if (E->isRValue()) + if (cast<InitListExpr>(E)->getNumInits() == 1) + return CheckICE(cast<InitListExpr>(E)->getInit(0), Ctx); + return ICEDiag(IK_NotICE, E->getLocStart()); + } + + case Expr::SizeOfPackExprClass: + case Expr::GNUNullExprClass: + // GCC considers the GNU __null value to be an integral constant expression. + return NoDiag(); + + case Expr::SubstNonTypeTemplateParmExprClass: + return + CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx); + + case Expr::ParenExprClass: + return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx); + case Expr::GenericSelectionExprClass: + return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx); + case Expr::IntegerLiteralClass: + case Expr::CharacterLiteralClass: + case Expr::ObjCBoolLiteralExprClass: + case Expr::CXXBoolLiteralExprClass: + case Expr::CXXScalarValueInitExprClass: + case Expr::TypeTraitExprClass: + case Expr::ArrayTypeTraitExprClass: + case Expr::ExpressionTraitExprClass: + case Expr::CXXNoexceptExprClass: + return NoDiag(); + case Expr::CallExprClass: + case Expr::CXXOperatorCallExprClass: { + // C99 6.6/3 allows function calls within unevaluated subexpressions of + // constant expressions, but they can never be ICEs because an ICE cannot + // contain an operand of (pointer to) function type. + const CallExpr *CE = cast<CallExpr>(E); + if (CE->getBuiltinCallee()) + return CheckEvalInICE(E, Ctx); + return ICEDiag(IK_NotICE, E->getLocStart()); + } + case Expr::DeclRefExprClass: { + if (isa<EnumConstantDecl>(cast<DeclRefExpr>(E)->getDecl())) + return NoDiag(); + const ValueDecl *D = dyn_cast<ValueDecl>(cast<DeclRefExpr>(E)->getDecl()); + if (Ctx.getLangOpts().CPlusPlus && + D && IsConstNonVolatile(D->getType())) { + // Parameter variables are never constants. Without this check, + // getAnyInitializer() can find a default argument, which leads + // to chaos. + if (isa<ParmVarDecl>(D)) + return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); + + // C++ 7.1.5.1p2 + // A variable of non-volatile const-qualified integral or enumeration + // type initialized by an ICE can be used in ICEs. + if (const VarDecl *Dcl = dyn_cast<VarDecl>(D)) { + if (!Dcl->getType()->isIntegralOrEnumerationType()) + return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); + + const VarDecl *VD; + // Look for a declaration of this variable that has an initializer, and + // check whether it is an ICE. + if (Dcl->getAnyInitializer(VD) && VD->checkInitIsICE()) + return NoDiag(); + else + return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); + } + } + return ICEDiag(IK_NotICE, E->getLocStart()); + } + case Expr::UnaryOperatorClass: { + const UnaryOperator *Exp = cast<UnaryOperator>(E); + switch (Exp->getOpcode()) { + case UO_PostInc: + case UO_PostDec: + case UO_PreInc: + case UO_PreDec: + case UO_AddrOf: + case UO_Deref: + // C99 6.6/3 allows increment and decrement within unevaluated + // subexpressions of constant expressions, but they can never be ICEs + // because an ICE cannot contain an lvalue operand. + return ICEDiag(IK_NotICE, E->getLocStart()); + case UO_Extension: + case UO_LNot: + case UO_Plus: + case UO_Minus: + case UO_Not: + case UO_Real: + case UO_Imag: + return CheckICE(Exp->getSubExpr(), Ctx); + } + + // OffsetOf falls through here. + } + case Expr::OffsetOfExprClass: { + // Note that per C99, offsetof must be an ICE. And AFAIK, using + // EvaluateAsRValue matches the proposed gcc behavior for cases like + // "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect + // compliance: we should warn earlier for offsetof expressions with + // array subscripts that aren't ICEs, and if the array subscripts + // are ICEs, the value of the offsetof must be an integer constant. + return CheckEvalInICE(E, Ctx); + } + case Expr::UnaryExprOrTypeTraitExprClass: { + const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E); + if ((Exp->getKind() == UETT_SizeOf) && + Exp->getTypeOfArgument()->isVariableArrayType()) + return ICEDiag(IK_NotICE, E->getLocStart()); + return NoDiag(); + } + case Expr::BinaryOperatorClass: { + const BinaryOperator *Exp = cast<BinaryOperator>(E); + switch (Exp->getOpcode()) { + case BO_PtrMemD: + case BO_PtrMemI: + case BO_Assign: + case BO_MulAssign: + case BO_DivAssign: + case BO_RemAssign: + case BO_AddAssign: + case BO_SubAssign: + case BO_ShlAssign: + case BO_ShrAssign: + case BO_AndAssign: + case BO_XorAssign: + case BO_OrAssign: + // C99 6.6/3 allows assignments within unevaluated subexpressions of + // constant expressions, but they can never be ICEs because an ICE cannot + // contain an lvalue operand. + return ICEDiag(IK_NotICE, E->getLocStart()); + + case BO_Mul: + case BO_Div: + case BO_Rem: + case BO_Add: + case BO_Sub: + case BO_Shl: + case BO_Shr: + case BO_LT: + case BO_GT: + case BO_LE: + case BO_GE: + case BO_EQ: + case BO_NE: + case BO_And: + case BO_Xor: + case BO_Or: + case BO_Comma: { + ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); + ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); + if (Exp->getOpcode() == BO_Div || + Exp->getOpcode() == BO_Rem) { + // EvaluateAsRValue gives an error for undefined Div/Rem, so make sure + // we don't evaluate one. + if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) { + llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx); + if (REval == 0) + return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); + if (REval.isSigned() && REval.isAllOnesValue()) { + llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx); + if (LEval.isMinSignedValue()) + return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); + } + } + } + if (Exp->getOpcode() == BO_Comma) { + if (Ctx.getLangOpts().C99) { + // C99 6.6p3 introduces a strange edge case: comma can be in an ICE + // if it isn't evaluated. + if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) + return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); + } else { + // In both C89 and C++, commas in ICEs are illegal. + return ICEDiag(IK_NotICE, E->getLocStart()); + } + } + return Worst(LHSResult, RHSResult); + } + case BO_LAnd: + case BO_LOr: { + ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); + ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); + if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) { + // Rare case where the RHS has a comma "side-effect"; we need + // to actually check the condition to see whether the side + // with the comma is evaluated. + if ((Exp->getOpcode() == BO_LAnd) != + (Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0)) + return RHSResult; + return NoDiag(); + } + + return Worst(LHSResult, RHSResult); + } + } + } + case Expr::ImplicitCastExprClass: + case Expr::CStyleCastExprClass: + case Expr::CXXFunctionalCastExprClass: + case Expr::CXXStaticCastExprClass: + case Expr::CXXReinterpretCastExprClass: + case Expr::CXXConstCastExprClass: + case Expr::ObjCBridgedCastExprClass: { + const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr(); + if (isa<ExplicitCastExpr>(E)) { + if (const FloatingLiteral *FL + = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) { + unsigned DestWidth = Ctx.getIntWidth(E->getType()); + bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType(); + APSInt IgnoredVal(DestWidth, !DestSigned); + bool Ignored; + // If the value does not fit in the destination type, the behavior is + // undefined, so we are not required to treat it as a constant + // expression. + if (FL->getValue().convertToInteger(IgnoredVal, + llvm::APFloat::rmTowardZero, + &Ignored) & APFloat::opInvalidOp) + return ICEDiag(IK_NotICE, E->getLocStart()); + return NoDiag(); + } + } + switch (cast<CastExpr>(E)->getCastKind()) { + case CK_LValueToRValue: + case CK_AtomicToNonAtomic: + case CK_NonAtomicToAtomic: + case CK_NoOp: + case CK_IntegralToBoolean: + case CK_IntegralCast: + return CheckICE(SubExpr, Ctx); + default: + return ICEDiag(IK_NotICE, E->getLocStart()); + } + } + case Expr::BinaryConditionalOperatorClass: { + const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E); + ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx); + if (CommonResult.Kind == IK_NotICE) return CommonResult; + ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); + if (FalseResult.Kind == IK_NotICE) return FalseResult; + if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult; + if (FalseResult.Kind == IK_ICEIfUnevaluated && + Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag(); + return FalseResult; + } + case Expr::ConditionalOperatorClass: { + const ConditionalOperator *Exp = cast<ConditionalOperator>(E); + // If the condition (ignoring parens) is a __builtin_constant_p call, + // then only the true side is actually considered in an integer constant + // expression, and it is fully evaluated. This is an important GNU + // extension. See GCC PR38377 for discussion. + if (const CallExpr *CallCE + = dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts())) + if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) + return CheckEvalInICE(E, Ctx); + ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx); + if (CondResult.Kind == IK_NotICE) + return CondResult; + + ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx); + ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); + + if (TrueResult.Kind == IK_NotICE) + return TrueResult; + if (FalseResult.Kind == IK_NotICE) + return FalseResult; + if (CondResult.Kind == IK_ICEIfUnevaluated) + return CondResult; + if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE) + return NoDiag(); + // Rare case where the diagnostics depend on which side is evaluated + // Note that if we get here, CondResult is 0, and at least one of + // TrueResult and FalseResult is non-zero. + if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0) + return FalseResult; + return TrueResult; + } + case Expr::CXXDefaultArgExprClass: + return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx); + case Expr::CXXDefaultInitExprClass: + return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx); + case Expr::ChooseExprClass: { + return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx); + } + } + + llvm_unreachable("Invalid StmtClass!"); +} + +/// Evaluate an expression as a C++11 integral constant expression. +static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx, + const Expr *E, + llvm::APSInt *Value, + SourceLocation *Loc) { + if (!E->getType()->isIntegralOrEnumerationType()) { + if (Loc) *Loc = E->getExprLoc(); + return false; + } + + APValue Result; + if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc)) + return false; + + if (!Result.isInt()) { + if (Loc) *Loc = E->getExprLoc(); + return false; + } + + if (Value) *Value = Result.getInt(); + return true; +} + +bool Expr::isIntegerConstantExpr(const ASTContext &Ctx, + SourceLocation *Loc) const { + if (Ctx.getLangOpts().CPlusPlus11) + return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, nullptr, Loc); + + ICEDiag D = CheckICE(this, Ctx); + if (D.Kind != IK_ICE) { + if (Loc) *Loc = D.Loc; + return false; + } + return true; +} + +bool Expr::isIntegerConstantExpr(llvm::APSInt &Value, const ASTContext &Ctx, + SourceLocation *Loc, bool isEvaluated) const { + if (Ctx.getLangOpts().CPlusPlus11) + return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc); + + if (!isIntegerConstantExpr(Ctx, Loc)) + return false; + if (!EvaluateAsInt(Value, Ctx)) + llvm_unreachable("ICE cannot be evaluated!"); + return true; +} + +bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const { + return CheckICE(this, Ctx).Kind == IK_ICE; +} + +bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result, + SourceLocation *Loc) const { + // We support this checking in C++98 mode in order to diagnose compatibility + // issues. + assert(Ctx.getLangOpts().CPlusPlus); + + // Build evaluation settings. + Expr::EvalStatus Status; + SmallVector<PartialDiagnosticAt, 8> Diags; + Status.Diag = &Diags; + EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression); + + APValue Scratch; + bool IsConstExpr = ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch); + + if (!Diags.empty()) { + IsConstExpr = false; + if (Loc) *Loc = Diags[0].first; + } else if (!IsConstExpr) { + // FIXME: This shouldn't happen. + if (Loc) *Loc = getExprLoc(); + } + + return IsConstExpr; +} + +bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx, + const FunctionDecl *Callee, + ArrayRef<const Expr*> Args) const { + Expr::EvalStatus Status; + EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated); + + ArgVector ArgValues(Args.size()); + for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end(); + I != E; ++I) { + if ((*I)->isValueDependent() || + !Evaluate(ArgValues[I - Args.begin()], Info, *I)) + // If evaluation fails, throw away the argument entirely. + ArgValues[I - Args.begin()] = APValue(); + if (Info.EvalStatus.HasSideEffects) + return false; + } + + // Build fake call to Callee. + CallStackFrame Frame(Info, Callee->getLocation(), Callee, /*This*/nullptr, + ArgValues.data()); + return Evaluate(Value, Info, this) && !Info.EvalStatus.HasSideEffects; +} + +bool Expr::isPotentialConstantExpr(const FunctionDecl *FD, + SmallVectorImpl< + PartialDiagnosticAt> &Diags) { + // FIXME: It would be useful to check constexpr function templates, but at the + // moment the constant expression evaluator cannot cope with the non-rigorous + // ASTs which we build for dependent expressions. + if (FD->isDependentContext()) + return true; + + Expr::EvalStatus Status; + Status.Diag = &Diags; + + EvalInfo Info(FD->getASTContext(), Status, + EvalInfo::EM_PotentialConstantExpression); + + const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); + const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr; + + // Fabricate an arbitrary expression on the stack and pretend that it + // is a temporary being used as the 'this' pointer. + LValue This; + ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy); + This.set(&VIE, Info.CurrentCall->Index); + + ArrayRef<const Expr*> Args; + + SourceLocation Loc = FD->getLocation(); + + APValue Scratch; + if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) { + // Evaluate the call as a constant initializer, to allow the construction + // of objects of non-literal types. + Info.setEvaluatingDecl(This.getLValueBase(), Scratch); + HandleConstructorCall(Loc, This, Args, CD, Info, Scratch); + } else + HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : nullptr, + Args, FD->getBody(), Info, Scratch); + + return Diags.empty(); +} + +bool Expr::isPotentialConstantExprUnevaluated(Expr *E, + const FunctionDecl *FD, + SmallVectorImpl< + PartialDiagnosticAt> &Diags) { + Expr::EvalStatus Status; + Status.Diag = &Diags; + + EvalInfo Info(FD->getASTContext(), Status, + EvalInfo::EM_PotentialConstantExpressionUnevaluated); + + // Fabricate a call stack frame to give the arguments a plausible cover story. + ArrayRef<const Expr*> Args; + ArgVector ArgValues(0); + bool Success = EvaluateArgs(Args, ArgValues, Info); + (void)Success; + assert(Success && + "Failed to set up arguments for potential constant evaluation"); + CallStackFrame Frame(Info, SourceLocation(), FD, nullptr, ArgValues.data()); + + APValue ResultScratch; + Evaluate(ResultScratch, Info, E); + return Diags.empty(); +} |
