1 //===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements the Expr constant evaluator. 11 // 12 // Constant expression evaluation produces four main results: 13 // 14 // * A success/failure flag indicating whether constant folding was successful. 15 // This is the 'bool' return value used by most of the code in this file. A 16 // 'false' return value indicates that constant folding has failed, and any 17 // appropriate diagnostic has already been produced. 18 // 19 // * An evaluated result, valid only if constant folding has not failed. 20 // 21 // * A flag indicating if evaluation encountered (unevaluated) side-effects. 22 // These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1), 23 // where it is possible to determine the evaluated result regardless. 24 // 25 // * A set of notes indicating why the evaluation was not a constant expression 26 // (under the C++11 rules only, at the moment), or, if folding failed too, 27 // why the expression could not be folded. 28 // 29 // If we are checking for a potential constant expression, failure to constant 30 // fold a potential constant sub-expression will be indicated by a 'false' 31 // return value (the expression could not be folded) and no diagnostic (the 32 // expression is not necessarily non-constant). 33 // 34 //===----------------------------------------------------------------------===// 35 36 #include "clang/AST/APValue.h" 37 #include "clang/AST/ASTContext.h" 38 #include "clang/AST/CharUnits.h" 39 #include "clang/AST/RecordLayout.h" 40 #include "clang/AST/StmtVisitor.h" 41 #include "clang/AST/TypeLoc.h" 42 #include "clang/AST/ASTDiagnostic.h" 43 #include "clang/AST/Expr.h" 44 #include "clang/Basic/Builtins.h" 45 #include "clang/Basic/TargetInfo.h" 46 #include "llvm/ADT/SmallString.h" 47 #include <cstring> 48 #include <functional> 49 50 using namespace clang; 51 using llvm::APSInt; 52 using llvm::APFloat; 53 54 static bool IsGlobalLValue(APValue::LValueBase B); 55 56 namespace { 57 struct LValue; 58 struct CallStackFrame; 59 struct EvalInfo; 60 61 static QualType getType(APValue::LValueBase B) { 62 if (!B) return QualType(); 63 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) 64 return D->getType(); 65 return B.get<const Expr*>()->getType(); 66 } 67 68 /// Get an LValue path entry, which is known to not be an array index, as a 69 /// field or base class. 70 static 71 APValue::BaseOrMemberType getAsBaseOrMember(APValue::LValuePathEntry E) { 72 APValue::BaseOrMemberType Value; 73 Value.setFromOpaqueValue(E.BaseOrMember); 74 return Value; 75 } 76 77 /// Get an LValue path entry, which is known to not be an array index, as a 78 /// field declaration. 79 static const FieldDecl *getAsField(APValue::LValuePathEntry E) { 80 return dyn_cast<FieldDecl>(getAsBaseOrMember(E).getPointer()); 81 } 82 /// Get an LValue path entry, which is known to not be an array index, as a 83 /// base class declaration. 84 static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) { 85 return dyn_cast<CXXRecordDecl>(getAsBaseOrMember(E).getPointer()); 86 } 87 /// Determine whether this LValue path entry for a base class names a virtual 88 /// base class. 89 static bool isVirtualBaseClass(APValue::LValuePathEntry E) { 90 return getAsBaseOrMember(E).getInt(); 91 } 92 93 /// Find the path length and type of the most-derived subobject in the given 94 /// path, and find the size of the containing array, if any. 95 static 96 unsigned findMostDerivedSubobject(ASTContext &Ctx, QualType Base, 97 ArrayRef<APValue::LValuePathEntry> Path, 98 uint64_t &ArraySize, QualType &Type) { 99 unsigned MostDerivedLength = 0; 100 Type = Base; 101 for (unsigned I = 0, N = Path.size(); I != N; ++I) { 102 if (Type->isArrayType()) { 103 const ConstantArrayType *CAT = 104 cast<ConstantArrayType>(Ctx.getAsArrayType(Type)); 105 Type = CAT->getElementType(); 106 ArraySize = CAT->getSize().getZExtValue(); 107 MostDerivedLength = I + 1; 108 } else if (Type->isAnyComplexType()) { 109 const ComplexType *CT = Type->castAs<ComplexType>(); 110 Type = CT->getElementType(); 111 ArraySize = 2; 112 MostDerivedLength = I + 1; 113 } else if (const FieldDecl *FD = getAsField(Path[I])) { 114 Type = FD->getType(); 115 ArraySize = 0; 116 MostDerivedLength = I + 1; 117 } else { 118 // Path[I] describes a base class. 119 ArraySize = 0; 120 } 121 } 122 return MostDerivedLength; 123 } 124 125 // The order of this enum is important for diagnostics. 126 enum CheckSubobjectKind { 127 CSK_Base, CSK_Derived, CSK_Field, CSK_ArrayToPointer, CSK_ArrayIndex, 128 CSK_This, CSK_Real, CSK_Imag 129 }; 130 131 /// A path from a glvalue to a subobject of that glvalue. 132 struct SubobjectDesignator { 133 /// True if the subobject was named in a manner not supported by C++11. Such 134 /// lvalues can still be folded, but they are not core constant expressions 135 /// and we cannot perform lvalue-to-rvalue conversions on them. 136 bool Invalid : 1; 137 138 /// Is this a pointer one past the end of an object? 139 bool IsOnePastTheEnd : 1; 140 141 /// The length of the path to the most-derived object of which this is a 142 /// subobject. 143 unsigned MostDerivedPathLength : 30; 144 145 /// The size of the array of which the most-derived object is an element, or 146 /// 0 if the most-derived object is not an array element. 147 uint64_t MostDerivedArraySize; 148 149 /// The type of the most derived object referred to by this address. 150 QualType MostDerivedType; 151 152 typedef APValue::LValuePathEntry PathEntry; 153 154 /// The entries on the path from the glvalue to the designated subobject. 155 SmallVector<PathEntry, 8> Entries; 156 157 SubobjectDesignator() : Invalid(true) {} 158 159 explicit SubobjectDesignator(QualType T) 160 : Invalid(false), IsOnePastTheEnd(false), MostDerivedPathLength(0), 161 MostDerivedArraySize(0), MostDerivedType(T) {} 162 163 SubobjectDesignator(ASTContext &Ctx, const APValue &V) 164 : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false), 165 MostDerivedPathLength(0), MostDerivedArraySize(0) { 166 if (!Invalid) { 167 IsOnePastTheEnd = V.isLValueOnePastTheEnd(); 168 ArrayRef<PathEntry> VEntries = V.getLValuePath(); 169 Entries.insert(Entries.end(), VEntries.begin(), VEntries.end()); 170 if (V.getLValueBase()) 171 MostDerivedPathLength = 172 findMostDerivedSubobject(Ctx, getType(V.getLValueBase()), 173 V.getLValuePath(), MostDerivedArraySize, 174 MostDerivedType); 175 } 176 } 177 178 void setInvalid() { 179 Invalid = true; 180 Entries.clear(); 181 } 182 183 /// Determine whether this is a one-past-the-end pointer. 184 bool isOnePastTheEnd() const { 185 if (IsOnePastTheEnd) 186 return true; 187 if (MostDerivedArraySize && 188 Entries[MostDerivedPathLength - 1].ArrayIndex == MostDerivedArraySize) 189 return true; 190 return false; 191 } 192 193 /// Check that this refers to a valid subobject. 194 bool isValidSubobject() const { 195 if (Invalid) 196 return false; 197 return !isOnePastTheEnd(); 198 } 199 /// Check that this refers to a valid subobject, and if not, produce a 200 /// relevant diagnostic and set the designator as invalid. 201 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK); 202 203 /// Update this designator to refer to the first element within this array. 204 void addArrayUnchecked(const ConstantArrayType *CAT) { 205 PathEntry Entry; 206 Entry.ArrayIndex = 0; 207 Entries.push_back(Entry); 208 209 // This is a most-derived object. 210 MostDerivedType = CAT->getElementType(); 211 MostDerivedArraySize = CAT->getSize().getZExtValue(); 212 MostDerivedPathLength = Entries.size(); 213 } 214 /// Update this designator to refer to the given base or member of this 215 /// object. 216 void addDeclUnchecked(const Decl *D, bool Virtual = false) { 217 PathEntry Entry; 218 APValue::BaseOrMemberType Value(D, Virtual); 219 Entry.BaseOrMember = Value.getOpaqueValue(); 220 Entries.push_back(Entry); 221 222 // If this isn't a base class, it's a new most-derived object. 223 if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) { 224 MostDerivedType = FD->getType(); 225 MostDerivedArraySize = 0; 226 MostDerivedPathLength = Entries.size(); 227 } 228 } 229 /// Update this designator to refer to the given complex component. 230 void addComplexUnchecked(QualType EltTy, bool Imag) { 231 PathEntry Entry; 232 Entry.ArrayIndex = Imag; 233 Entries.push_back(Entry); 234 235 // This is technically a most-derived object, though in practice this 236 // is unlikely to matter. 237 MostDerivedType = EltTy; 238 MostDerivedArraySize = 2; 239 MostDerivedPathLength = Entries.size(); 240 } 241 void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, uint64_t N); 242 /// Add N to the address of this subobject. 243 void adjustIndex(EvalInfo &Info, const Expr *E, uint64_t N) { 244 if (Invalid) return; 245 if (MostDerivedPathLength == Entries.size() && MostDerivedArraySize) { 246 Entries.back().ArrayIndex += N; 247 if (Entries.back().ArrayIndex > MostDerivedArraySize) { 248 diagnosePointerArithmetic(Info, E, Entries.back().ArrayIndex); 249 setInvalid(); 250 } 251 return; 252 } 253 // [expr.add]p4: For the purposes of these operators, a pointer to a 254 // nonarray object behaves the same as a pointer to the first element of 255 // an array of length one with the type of the object as its element type. 256 if (IsOnePastTheEnd && N == (uint64_t)-1) 257 IsOnePastTheEnd = false; 258 else if (!IsOnePastTheEnd && N == 1) 259 IsOnePastTheEnd = true; 260 else if (N != 0) { 261 diagnosePointerArithmetic(Info, E, uint64_t(IsOnePastTheEnd) + N); 262 setInvalid(); 263 } 264 } 265 }; 266 267 /// A stack frame in the constexpr call stack. 268 struct CallStackFrame { 269 EvalInfo &Info; 270 271 /// Parent - The caller of this stack frame. 272 CallStackFrame *Caller; 273 274 /// CallLoc - The location of the call expression for this call. 275 SourceLocation CallLoc; 276 277 /// Callee - The function which was called. 278 const FunctionDecl *Callee; 279 280 /// Index - The call index of this call. 281 unsigned Index; 282 283 /// This - The binding for the this pointer in this call, if any. 284 const LValue *This; 285 286 /// ParmBindings - Parameter bindings for this function call, indexed by 287 /// parameters' function scope indices. 288 const APValue *Arguments; 289 290 // Note that we intentionally use std::map here so that references to 291 // values are stable. 292 typedef std::map<const Expr*, APValue> MapTy; 293 typedef MapTy::const_iterator temp_iterator; 294 /// Temporaries - Temporary lvalues materialized within this stack frame. 295 MapTy Temporaries; 296 297 CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, 298 const FunctionDecl *Callee, const LValue *This, 299 const APValue *Arguments); 300 ~CallStackFrame(); 301 }; 302 303 /// A partial diagnostic which we might know in advance that we are not going 304 /// to emit. 305 class OptionalDiagnostic { 306 PartialDiagnostic *Diag; 307 308 public: 309 explicit OptionalDiagnostic(PartialDiagnostic *Diag = 0) : Diag(Diag) {} 310 311 template<typename T> 312 OptionalDiagnostic &operator<<(const T &v) { 313 if (Diag) 314 *Diag << v; 315 return *this; 316 } 317 318 OptionalDiagnostic &operator<<(const APSInt &I) { 319 if (Diag) { 320 llvm::SmallVector<char, 32> Buffer; 321 I.toString(Buffer); 322 *Diag << StringRef(Buffer.data(), Buffer.size()); 323 } 324 return *this; 325 } 326 327 OptionalDiagnostic &operator<<(const APFloat &F) { 328 if (Diag) { 329 llvm::SmallVector<char, 32> Buffer; 330 F.toString(Buffer); 331 *Diag << StringRef(Buffer.data(), Buffer.size()); 332 } 333 return *this; 334 } 335 }; 336 337 /// EvalInfo - This is a private struct used by the evaluator to capture 338 /// information about a subexpression as it is folded. It retains information 339 /// about the AST context, but also maintains information about the folded 340 /// expression. 341 /// 342 /// If an expression could be evaluated, it is still possible it is not a C 343 /// "integer constant expression" or constant expression. If not, this struct 344 /// captures information about how and why not. 345 /// 346 /// One bit of information passed *into* the request for constant folding 347 /// indicates whether the subexpression is "evaluated" or not according to C 348 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can 349 /// evaluate the expression regardless of what the RHS is, but C only allows 350 /// certain things in certain situations. 351 struct EvalInfo { 352 ASTContext &Ctx; 353 354 /// EvalStatus - Contains information about the evaluation. 355 Expr::EvalStatus &EvalStatus; 356 357 /// CurrentCall - The top of the constexpr call stack. 358 CallStackFrame *CurrentCall; 359 360 /// CallStackDepth - The number of calls in the call stack right now. 361 unsigned CallStackDepth; 362 363 /// NextCallIndex - The next call index to assign. 364 unsigned NextCallIndex; 365 366 /// BottomFrame - The frame in which evaluation started. This must be 367 /// initialized after CurrentCall and CallStackDepth. 368 CallStackFrame BottomFrame; 369 370 /// EvaluatingDecl - This is the declaration whose initializer is being 371 /// evaluated, if any. 372 const VarDecl *EvaluatingDecl; 373 374 /// EvaluatingDeclValue - This is the value being constructed for the 375 /// declaration whose initializer is being evaluated, if any. 376 APValue *EvaluatingDeclValue; 377 378 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further 379 /// notes attached to it will also be stored, otherwise they will not be. 380 bool HasActiveDiagnostic; 381 382 /// CheckingPotentialConstantExpression - Are we checking whether the 383 /// expression is a potential constant expression? If so, some diagnostics 384 /// are suppressed. 385 bool CheckingPotentialConstantExpression; 386 387 EvalInfo(const ASTContext &C, Expr::EvalStatus &S) 388 : Ctx(const_cast<ASTContext&>(C)), EvalStatus(S), CurrentCall(0), 389 CallStackDepth(0), NextCallIndex(1), 390 BottomFrame(*this, SourceLocation(), 0, 0, 0), 391 EvaluatingDecl(0), EvaluatingDeclValue(0), HasActiveDiagnostic(false), 392 CheckingPotentialConstantExpression(false) {} 393 394 void setEvaluatingDecl(const VarDecl *VD, APValue &Value) { 395 EvaluatingDecl = VD; 396 EvaluatingDeclValue = &Value; 397 } 398 399 const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); } 400 401 bool CheckCallLimit(SourceLocation Loc) { 402 // Don't perform any constexpr calls (other than the call we're checking) 403 // when checking a potential constant expression. 404 if (CheckingPotentialConstantExpression && CallStackDepth > 1) 405 return false; 406 if (NextCallIndex == 0) { 407 // NextCallIndex has wrapped around. 408 Diag(Loc, diag::note_constexpr_call_limit_exceeded); 409 return false; 410 } 411 if (CallStackDepth <= getLangOpts().ConstexprCallDepth) 412 return true; 413 Diag(Loc, diag::note_constexpr_depth_limit_exceeded) 414 << getLangOpts().ConstexprCallDepth; 415 return false; 416 } 417 418 CallStackFrame *getCallFrame(unsigned CallIndex) { 419 assert(CallIndex && "no call index in getCallFrame"); 420 // We will eventually hit BottomFrame, which has Index 1, so Frame can't 421 // be null in this loop. 422 CallStackFrame *Frame = CurrentCall; 423 while (Frame->Index > CallIndex) 424 Frame = Frame->Caller; 425 return (Frame->Index == CallIndex) ? Frame : 0; 426 } 427 428 private: 429 /// Add a diagnostic to the diagnostics list. 430 PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId) { 431 PartialDiagnostic PD(DiagId, Ctx.getDiagAllocator()); 432 EvalStatus.Diag->push_back(std::make_pair(Loc, PD)); 433 return EvalStatus.Diag->back().second; 434 } 435 436 /// Add notes containing a call stack to the current point of evaluation. 437 void addCallStack(unsigned Limit); 438 439 public: 440 /// Diagnose that the evaluation cannot be folded. 441 OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId 442 = diag::note_invalid_subexpr_in_const_expr, 443 unsigned ExtraNotes = 0) { 444 // If we have a prior diagnostic, it will be noting that the expression 445 // isn't a constant expression. This diagnostic is more important. 446 // FIXME: We might want to show both diagnostics to the user. 447 if (EvalStatus.Diag) { 448 unsigned CallStackNotes = CallStackDepth - 1; 449 unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit(); 450 if (Limit) 451 CallStackNotes = std::min(CallStackNotes, Limit + 1); 452 if (CheckingPotentialConstantExpression) 453 CallStackNotes = 0; 454 455 HasActiveDiagnostic = true; 456 EvalStatus.Diag->clear(); 457 EvalStatus.Diag->reserve(1 + ExtraNotes + CallStackNotes); 458 addDiag(Loc, DiagId); 459 if (!CheckingPotentialConstantExpression) 460 addCallStack(Limit); 461 return OptionalDiagnostic(&(*EvalStatus.Diag)[0].second); 462 } 463 HasActiveDiagnostic = false; 464 return OptionalDiagnostic(); 465 } 466 467 OptionalDiagnostic Diag(const Expr *E, diag::kind DiagId 468 = diag::note_invalid_subexpr_in_const_expr, 469 unsigned ExtraNotes = 0) { 470 if (EvalStatus.Diag) 471 return Diag(E->getExprLoc(), DiagId, ExtraNotes); 472 HasActiveDiagnostic = false; 473 return OptionalDiagnostic(); 474 } 475 476 /// Diagnose that the evaluation does not produce a C++11 core constant 477 /// expression. 478 template<typename LocArg> 479 OptionalDiagnostic CCEDiag(LocArg Loc, diag::kind DiagId 480 = diag::note_invalid_subexpr_in_const_expr, 481 unsigned ExtraNotes = 0) { 482 // Don't override a previous diagnostic. 483 if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) { 484 HasActiveDiagnostic = false; 485 return OptionalDiagnostic(); 486 } 487 return Diag(Loc, DiagId, ExtraNotes); 488 } 489 490 /// Add a note to a prior diagnostic. 491 OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId) { 492 if (!HasActiveDiagnostic) 493 return OptionalDiagnostic(); 494 return OptionalDiagnostic(&addDiag(Loc, DiagId)); 495 } 496 497 /// Add a stack of notes to a prior diagnostic. 498 void addNotes(ArrayRef<PartialDiagnosticAt> Diags) { 499 if (HasActiveDiagnostic) { 500 EvalStatus.Diag->insert(EvalStatus.Diag->end(), 501 Diags.begin(), Diags.end()); 502 } 503 } 504 505 /// Should we continue evaluation as much as possible after encountering a 506 /// construct which can't be folded? 507 bool keepEvaluatingAfterFailure() { 508 return CheckingPotentialConstantExpression && 509 EvalStatus.Diag && EvalStatus.Diag->empty(); 510 } 511 }; 512 513 /// Object used to treat all foldable expressions as constant expressions. 514 struct FoldConstant { 515 bool Enabled; 516 517 explicit FoldConstant(EvalInfo &Info) 518 : Enabled(Info.EvalStatus.Diag && Info.EvalStatus.Diag->empty() && 519 !Info.EvalStatus.HasSideEffects) { 520 } 521 // Treat the value we've computed since this object was created as constant. 522 void Fold(EvalInfo &Info) { 523 if (Enabled && !Info.EvalStatus.Diag->empty() && 524 !Info.EvalStatus.HasSideEffects) 525 Info.EvalStatus.Diag->clear(); 526 } 527 }; 528 529 /// RAII object used to suppress diagnostics and side-effects from a 530 /// speculative evaluation. 531 class SpeculativeEvaluationRAII { 532 EvalInfo &Info; 533 Expr::EvalStatus Old; 534 535 public: 536 SpeculativeEvaluationRAII(EvalInfo &Info, 537 llvm::SmallVectorImpl<PartialDiagnosticAt> 538 *NewDiag = 0) 539 : Info(Info), Old(Info.EvalStatus) { 540 Info.EvalStatus.Diag = NewDiag; 541 } 542 ~SpeculativeEvaluationRAII() { 543 Info.EvalStatus = Old; 544 } 545 }; 546 } 547 548 bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E, 549 CheckSubobjectKind CSK) { 550 if (Invalid) 551 return false; 552 if (isOnePastTheEnd()) { 553 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject) 554 << CSK; 555 setInvalid(); 556 return false; 557 } 558 return true; 559 } 560 561 void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info, 562 const Expr *E, uint64_t N) { 563 if (MostDerivedPathLength == Entries.size() && MostDerivedArraySize) 564 Info.CCEDiag(E, diag::note_constexpr_array_index) 565 << static_cast<int>(N) << /*array*/ 0 566 << static_cast<unsigned>(MostDerivedArraySize); 567 else 568 Info.CCEDiag(E, diag::note_constexpr_array_index) 569 << static_cast<int>(N) << /*non-array*/ 1; 570 setInvalid(); 571 } 572 573 CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, 574 const FunctionDecl *Callee, const LValue *This, 575 const APValue *Arguments) 576 : Info(Info), Caller(Info.CurrentCall), CallLoc(CallLoc), Callee(Callee), 577 Index(Info.NextCallIndex++), This(This), Arguments(Arguments) { 578 Info.CurrentCall = this; 579 ++Info.CallStackDepth; 580 } 581 582 CallStackFrame::~CallStackFrame() { 583 assert(Info.CurrentCall == this && "calls retired out of order"); 584 --Info.CallStackDepth; 585 Info.CurrentCall = Caller; 586 } 587 588 /// Produce a string describing the given constexpr call. 589 static void describeCall(CallStackFrame *Frame, llvm::raw_ostream &Out) { 590 unsigned ArgIndex = 0; 591 bool IsMemberCall = isa<CXXMethodDecl>(Frame->Callee) && 592 !isa<CXXConstructorDecl>(Frame->Callee) && 593 cast<CXXMethodDecl>(Frame->Callee)->isInstance(); 594 595 if (!IsMemberCall) 596 Out << *Frame->Callee << '('; 597 598 for (FunctionDecl::param_const_iterator I = Frame->Callee->param_begin(), 599 E = Frame->Callee->param_end(); I != E; ++I, ++ArgIndex) { 600 if (ArgIndex > (unsigned)IsMemberCall) 601 Out << ", "; 602 603 const ParmVarDecl *Param = *I; 604 const APValue &Arg = Frame->Arguments[ArgIndex]; 605 Arg.printPretty(Out, Frame->Info.Ctx, Param->getType()); 606 607 if (ArgIndex == 0 && IsMemberCall) 608 Out << "->" << *Frame->Callee << '('; 609 } 610 611 Out << ')'; 612 } 613 614 void EvalInfo::addCallStack(unsigned Limit) { 615 // Determine which calls to skip, if any. 616 unsigned ActiveCalls = CallStackDepth - 1; 617 unsigned SkipStart = ActiveCalls, SkipEnd = SkipStart; 618 if (Limit && Limit < ActiveCalls) { 619 SkipStart = Limit / 2 + Limit % 2; 620 SkipEnd = ActiveCalls - Limit / 2; 621 } 622 623 // Walk the call stack and add the diagnostics. 624 unsigned CallIdx = 0; 625 for (CallStackFrame *Frame = CurrentCall; Frame != &BottomFrame; 626 Frame = Frame->Caller, ++CallIdx) { 627 // Skip this call? 628 if (CallIdx >= SkipStart && CallIdx < SkipEnd) { 629 if (CallIdx == SkipStart) { 630 // Note that we're skipping calls. 631 addDiag(Frame->CallLoc, diag::note_constexpr_calls_suppressed) 632 << unsigned(ActiveCalls - Limit); 633 } 634 continue; 635 } 636 637 llvm::SmallVector<char, 128> Buffer; 638 llvm::raw_svector_ostream Out(Buffer); 639 describeCall(Frame, Out); 640 addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str(); 641 } 642 } 643 644 namespace { 645 struct ComplexValue { 646 private: 647 bool IsInt; 648 649 public: 650 APSInt IntReal, IntImag; 651 APFloat FloatReal, FloatImag; 652 653 ComplexValue() : FloatReal(APFloat::Bogus), FloatImag(APFloat::Bogus) {} 654 655 void makeComplexFloat() { IsInt = false; } 656 bool isComplexFloat() const { return !IsInt; } 657 APFloat &getComplexFloatReal() { return FloatReal; } 658 APFloat &getComplexFloatImag() { return FloatImag; } 659 660 void makeComplexInt() { IsInt = true; } 661 bool isComplexInt() const { return IsInt; } 662 APSInt &getComplexIntReal() { return IntReal; } 663 APSInt &getComplexIntImag() { return IntImag; } 664 665 void moveInto(APValue &v) const { 666 if (isComplexFloat()) 667 v = APValue(FloatReal, FloatImag); 668 else 669 v = APValue(IntReal, IntImag); 670 } 671 void setFrom(const APValue &v) { 672 assert(v.isComplexFloat() || v.isComplexInt()); 673 if (v.isComplexFloat()) { 674 makeComplexFloat(); 675 FloatReal = v.getComplexFloatReal(); 676 FloatImag = v.getComplexFloatImag(); 677 } else { 678 makeComplexInt(); 679 IntReal = v.getComplexIntReal(); 680 IntImag = v.getComplexIntImag(); 681 } 682 } 683 }; 684 685 struct LValue { 686 APValue::LValueBase Base; 687 CharUnits Offset; 688 unsigned CallIndex; 689 SubobjectDesignator Designator; 690 691 const APValue::LValueBase getLValueBase() const { return Base; } 692 CharUnits &getLValueOffset() { return Offset; } 693 const CharUnits &getLValueOffset() const { return Offset; } 694 unsigned getLValueCallIndex() const { return CallIndex; } 695 SubobjectDesignator &getLValueDesignator() { return Designator; } 696 const SubobjectDesignator &getLValueDesignator() const { return Designator;} 697 698 void moveInto(APValue &V) const { 699 if (Designator.Invalid) 700 V = APValue(Base, Offset, APValue::NoLValuePath(), CallIndex); 701 else 702 V = APValue(Base, Offset, Designator.Entries, 703 Designator.IsOnePastTheEnd, CallIndex); 704 } 705 void setFrom(ASTContext &Ctx, const APValue &V) { 706 assert(V.isLValue()); 707 Base = V.getLValueBase(); 708 Offset = V.getLValueOffset(); 709 CallIndex = V.getLValueCallIndex(); 710 Designator = SubobjectDesignator(Ctx, V); 711 } 712 713 void set(APValue::LValueBase B, unsigned I = 0) { 714 Base = B; 715 Offset = CharUnits::Zero(); 716 CallIndex = I; 717 Designator = SubobjectDesignator(getType(B)); 718 } 719 720 // Check that this LValue is not based on a null pointer. If it is, produce 721 // a diagnostic and mark the designator as invalid. 722 bool checkNullPointer(EvalInfo &Info, const Expr *E, 723 CheckSubobjectKind CSK) { 724 if (Designator.Invalid) 725 return false; 726 if (!Base) { 727 Info.CCEDiag(E, diag::note_constexpr_null_subobject) 728 << CSK; 729 Designator.setInvalid(); 730 return false; 731 } 732 return true; 733 } 734 735 // Check this LValue refers to an object. If not, set the designator to be 736 // invalid and emit a diagnostic. 737 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { 738 // Outside C++11, do not build a designator referring to a subobject of 739 // any object: we won't use such a designator for anything. 740 if (!Info.getLangOpts().CPlusPlus0x) 741 Designator.setInvalid(); 742 return checkNullPointer(Info, E, CSK) && 743 Designator.checkSubobject(Info, E, CSK); 744 } 745 746 void addDecl(EvalInfo &Info, const Expr *E, 747 const Decl *D, bool Virtual = false) { 748 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base)) 749 Designator.addDeclUnchecked(D, Virtual); 750 } 751 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) { 752 if (checkSubobject(Info, E, CSK_ArrayToPointer)) 753 Designator.addArrayUnchecked(CAT); 754 } 755 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) { 756 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real)) 757 Designator.addComplexUnchecked(EltTy, Imag); 758 } 759 void adjustIndex(EvalInfo &Info, const Expr *E, uint64_t N) { 760 if (checkNullPointer(Info, E, CSK_ArrayIndex)) 761 Designator.adjustIndex(Info, E, N); 762 } 763 }; 764 765 struct MemberPtr { 766 MemberPtr() {} 767 explicit MemberPtr(const ValueDecl *Decl) : 768 DeclAndIsDerivedMember(Decl, false), Path() {} 769 770 /// The member or (direct or indirect) field referred to by this member 771 /// pointer, or 0 if this is a null member pointer. 772 const ValueDecl *getDecl() const { 773 return DeclAndIsDerivedMember.getPointer(); 774 } 775 /// Is this actually a member of some type derived from the relevant class? 776 bool isDerivedMember() const { 777 return DeclAndIsDerivedMember.getInt(); 778 } 779 /// Get the class which the declaration actually lives in. 780 const CXXRecordDecl *getContainingRecord() const { 781 return cast<CXXRecordDecl>( 782 DeclAndIsDerivedMember.getPointer()->getDeclContext()); 783 } 784 785 void moveInto(APValue &V) const { 786 V = APValue(getDecl(), isDerivedMember(), Path); 787 } 788 void setFrom(const APValue &V) { 789 assert(V.isMemberPointer()); 790 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl()); 791 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember()); 792 Path.clear(); 793 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath(); 794 Path.insert(Path.end(), P.begin(), P.end()); 795 } 796 797 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating 798 /// whether the member is a member of some class derived from the class type 799 /// of the member pointer. 800 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember; 801 /// Path - The path of base/derived classes from the member declaration's 802 /// class (exclusive) to the class type of the member pointer (inclusive). 803 SmallVector<const CXXRecordDecl*, 4> Path; 804 805 /// Perform a cast towards the class of the Decl (either up or down the 806 /// hierarchy). 807 bool castBack(const CXXRecordDecl *Class) { 808 assert(!Path.empty()); 809 const CXXRecordDecl *Expected; 810 if (Path.size() >= 2) 811 Expected = Path[Path.size() - 2]; 812 else 813 Expected = getContainingRecord(); 814 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) { 815 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*), 816 // if B does not contain the original member and is not a base or 817 // derived class of the class containing the original member, the result 818 // of the cast is undefined. 819 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to 820 // (D::*). We consider that to be a language defect. 821 return false; 822 } 823 Path.pop_back(); 824 return true; 825 } 826 /// Perform a base-to-derived member pointer cast. 827 bool castToDerived(const CXXRecordDecl *Derived) { 828 if (!getDecl()) 829 return true; 830 if (!isDerivedMember()) { 831 Path.push_back(Derived); 832 return true; 833 } 834 if (!castBack(Derived)) 835 return false; 836 if (Path.empty()) 837 DeclAndIsDerivedMember.setInt(false); 838 return true; 839 } 840 /// Perform a derived-to-base member pointer cast. 841 bool castToBase(const CXXRecordDecl *Base) { 842 if (!getDecl()) 843 return true; 844 if (Path.empty()) 845 DeclAndIsDerivedMember.setInt(true); 846 if (isDerivedMember()) { 847 Path.push_back(Base); 848 return true; 849 } 850 return castBack(Base); 851 } 852 }; 853 854 /// Compare two member pointers, which are assumed to be of the same type. 855 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) { 856 if (!LHS.getDecl() || !RHS.getDecl()) 857 return !LHS.getDecl() && !RHS.getDecl(); 858 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl()) 859 return false; 860 return LHS.Path == RHS.Path; 861 } 862 863 /// Kinds of constant expression checking, for diagnostics. 864 enum CheckConstantExpressionKind { 865 CCEK_Constant, ///< A normal constant. 866 CCEK_ReturnValue, ///< A constexpr function return value. 867 CCEK_MemberInit ///< A constexpr constructor mem-initializer. 868 }; 869 } 870 871 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E); 872 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, 873 const LValue &This, const Expr *E, 874 CheckConstantExpressionKind CCEK = CCEK_Constant, 875 bool AllowNonLiteralTypes = false); 876 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info); 877 static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info); 878 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, 879 EvalInfo &Info); 880 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info); 881 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info); 882 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, 883 EvalInfo &Info); 884 static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info); 885 static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info); 886 887 //===----------------------------------------------------------------------===// 888 // Misc utilities 889 //===----------------------------------------------------------------------===// 890 891 /// Should this call expression be treated as a string literal? 892 static bool IsStringLiteralCall(const CallExpr *E) { 893 unsigned Builtin = E->isBuiltinCall(); 894 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString || 895 Builtin == Builtin::BI__builtin___NSStringMakeConstantString); 896 } 897 898 static bool IsGlobalLValue(APValue::LValueBase B) { 899 // C++11 [expr.const]p3 An address constant expression is a prvalue core 900 // constant expression of pointer type that evaluates to... 901 902 // ... a null pointer value, or a prvalue core constant expression of type 903 // std::nullptr_t. 904 if (!B) return true; 905 906 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { 907 // ... the address of an object with static storage duration, 908 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 909 return VD->hasGlobalStorage(); 910 // ... the address of a function, 911 return isa<FunctionDecl>(D); 912 } 913 914 const Expr *E = B.get<const Expr*>(); 915 switch (E->getStmtClass()) { 916 default: 917 return false; 918 case Expr::CompoundLiteralExprClass: { 919 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 920 return CLE->isFileScope() && CLE->isLValue(); 921 } 922 // A string literal has static storage duration. 923 case Expr::StringLiteralClass: 924 case Expr::PredefinedExprClass: 925 case Expr::ObjCStringLiteralClass: 926 case Expr::ObjCEncodeExprClass: 927 case Expr::CXXTypeidExprClass: 928 case Expr::CXXUuidofExprClass: 929 return true; 930 case Expr::CallExprClass: 931 return IsStringLiteralCall(cast<CallExpr>(E)); 932 // For GCC compatibility, &&label has static storage duration. 933 case Expr::AddrLabelExprClass: 934 return true; 935 // A Block literal expression may be used as the initialization value for 936 // Block variables at global or local static scope. 937 case Expr::BlockExprClass: 938 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures(); 939 case Expr::ImplicitValueInitExprClass: 940 // FIXME: 941 // We can never form an lvalue with an implicit value initialization as its 942 // base through expression evaluation, so these only appear in one case: the 943 // implicit variable declaration we invent when checking whether a constexpr 944 // constructor can produce a constant expression. We must assume that such 945 // an expression might be a global lvalue. 946 return true; 947 } 948 } 949 950 static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) { 951 assert(Base && "no location for a null lvalue"); 952 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 953 if (VD) 954 Info.Note(VD->getLocation(), diag::note_declared_at); 955 else 956 Info.Note(Base.get<const Expr*>()->getExprLoc(), 957 diag::note_constexpr_temporary_here); 958 } 959 960 /// Check that this reference or pointer core constant expression is a valid 961 /// value for an address or reference constant expression. Return true if we 962 /// can fold this expression, whether or not it's a constant expression. 963 static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc, 964 QualType Type, const LValue &LVal) { 965 bool IsReferenceType = Type->isReferenceType(); 966 967 APValue::LValueBase Base = LVal.getLValueBase(); 968 const SubobjectDesignator &Designator = LVal.getLValueDesignator(); 969 970 // Check that the object is a global. Note that the fake 'this' object we 971 // manufacture when checking potential constant expressions is conservatively 972 // assumed to be global here. 973 if (!IsGlobalLValue(Base)) { 974 if (Info.getLangOpts().CPlusPlus0x) { 975 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 976 Info.Diag(Loc, diag::note_constexpr_non_global, 1) 977 << IsReferenceType << !Designator.Entries.empty() 978 << !!VD << VD; 979 NoteLValueLocation(Info, Base); 980 } else { 981 Info.Diag(Loc); 982 } 983 // Don't allow references to temporaries to escape. 984 return false; 985 } 986 assert((Info.CheckingPotentialConstantExpression || 987 LVal.getLValueCallIndex() == 0) && 988 "have call index for global lvalue"); 989 990 // Check if this is a thread-local variable. 991 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) { 992 if (const VarDecl *Var = dyn_cast<const VarDecl>(VD)) { 993 if (Var->isThreadSpecified()) 994 return false; 995 } 996 } 997 998 // Allow address constant expressions to be past-the-end pointers. This is 999 // an extension: the standard requires them to point to an object. 1000 if (!IsReferenceType) 1001 return true; 1002 1003 // A reference constant expression must refer to an object. 1004 if (!Base) { 1005 // FIXME: diagnostic 1006 Info.CCEDiag(Loc); 1007 return true; 1008 } 1009 1010 // Does this refer one past the end of some object? 1011 if (Designator.isOnePastTheEnd()) { 1012 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 1013 Info.Diag(Loc, diag::note_constexpr_past_end, 1) 1014 << !Designator.Entries.empty() << !!VD << VD; 1015 NoteLValueLocation(Info, Base); 1016 } 1017 1018 return true; 1019 } 1020 1021 /// Check that this core constant expression is of literal type, and if not, 1022 /// produce an appropriate diagnostic. 1023 static bool CheckLiteralType(EvalInfo &Info, const Expr *E) { 1024 if (!E->isRValue() || E->getType()->isLiteralType()) 1025 return true; 1026 1027 // Prvalue constant expressions must be of literal types. 1028 if (Info.getLangOpts().CPlusPlus0x) 1029 Info.Diag(E, diag::note_constexpr_nonliteral) 1030 << E->getType(); 1031 else 1032 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1033 return false; 1034 } 1035 1036 /// Check that this core constant expression value is a valid value for a 1037 /// constant expression. If not, report an appropriate diagnostic. Does not 1038 /// check that the expression is of literal type. 1039 static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, 1040 QualType Type, const APValue &Value) { 1041 // Core issue 1454: For a literal constant expression of array or class type, 1042 // each subobject of its value shall have been initialized by a constant 1043 // expression. 1044 if (Value.isArray()) { 1045 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType(); 1046 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) { 1047 if (!CheckConstantExpression(Info, DiagLoc, EltTy, 1048 Value.getArrayInitializedElt(I))) 1049 return false; 1050 } 1051 if (!Value.hasArrayFiller()) 1052 return true; 1053 return CheckConstantExpression(Info, DiagLoc, EltTy, 1054 Value.getArrayFiller()); 1055 } 1056 if (Value.isUnion() && Value.getUnionField()) { 1057 return CheckConstantExpression(Info, DiagLoc, 1058 Value.getUnionField()->getType(), 1059 Value.getUnionValue()); 1060 } 1061 if (Value.isStruct()) { 1062 RecordDecl *RD = Type->castAs<RecordType>()->getDecl(); 1063 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) { 1064 unsigned BaseIndex = 0; 1065 for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), 1066 End = CD->bases_end(); I != End; ++I, ++BaseIndex) { 1067 if (!CheckConstantExpression(Info, DiagLoc, I->getType(), 1068 Value.getStructBase(BaseIndex))) 1069 return false; 1070 } 1071 } 1072 for (RecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end(); 1073 I != E; ++I) { 1074 if (!CheckConstantExpression(Info, DiagLoc, I->getType(), 1075 Value.getStructField(I->getFieldIndex()))) 1076 return false; 1077 } 1078 } 1079 1080 if (Value.isLValue()) { 1081 LValue LVal; 1082 LVal.setFrom(Info.Ctx, Value); 1083 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal); 1084 } 1085 1086 // Everything else is fine. 1087 return true; 1088 } 1089 1090 const ValueDecl *GetLValueBaseDecl(const LValue &LVal) { 1091 return LVal.Base.dyn_cast<const ValueDecl*>(); 1092 } 1093 1094 static bool IsLiteralLValue(const LValue &Value) { 1095 return Value.Base.dyn_cast<const Expr*>() && !Value.CallIndex; 1096 } 1097 1098 static bool IsWeakLValue(const LValue &Value) { 1099 const ValueDecl *Decl = GetLValueBaseDecl(Value); 1100 return Decl && Decl->isWeak(); 1101 } 1102 1103 static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) { 1104 // A null base expression indicates a null pointer. These are always 1105 // evaluatable, and they are false unless the offset is zero. 1106 if (!Value.getLValueBase()) { 1107 Result = !Value.getLValueOffset().isZero(); 1108 return true; 1109 } 1110 1111 // We have a non-null base. These are generally known to be true, but if it's 1112 // a weak declaration it can be null at runtime. 1113 Result = true; 1114 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>(); 1115 return !Decl || !Decl->isWeak(); 1116 } 1117 1118 static bool HandleConversionToBool(const APValue &Val, bool &Result) { 1119 switch (Val.getKind()) { 1120 case APValue::Uninitialized: 1121 return false; 1122 case APValue::Int: 1123 Result = Val.getInt().getBoolValue(); 1124 return true; 1125 case APValue::Float: 1126 Result = !Val.getFloat().isZero(); 1127 return true; 1128 case APValue::ComplexInt: 1129 Result = Val.getComplexIntReal().getBoolValue() || 1130 Val.getComplexIntImag().getBoolValue(); 1131 return true; 1132 case APValue::ComplexFloat: 1133 Result = !Val.getComplexFloatReal().isZero() || 1134 !Val.getComplexFloatImag().isZero(); 1135 return true; 1136 case APValue::LValue: 1137 return EvalPointerValueAsBool(Val, Result); 1138 case APValue::MemberPointer: 1139 Result = Val.getMemberPointerDecl(); 1140 return true; 1141 case APValue::Vector: 1142 case APValue::Array: 1143 case APValue::Struct: 1144 case APValue::Union: 1145 case APValue::AddrLabelDiff: 1146 return false; 1147 } 1148 1149 llvm_unreachable("unknown APValue kind"); 1150 } 1151 1152 static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result, 1153 EvalInfo &Info) { 1154 assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition"); 1155 APValue Val; 1156 if (!Evaluate(Val, Info, E)) 1157 return false; 1158 return HandleConversionToBool(Val, Result); 1159 } 1160 1161 template<typename T> 1162 static void HandleOverflow(EvalInfo &Info, const Expr *E, 1163 const T &SrcValue, QualType DestType) { 1164 Info.CCEDiag(E, diag::note_constexpr_overflow) 1165 << SrcValue << DestType; 1166 } 1167 1168 static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E, 1169 QualType SrcType, const APFloat &Value, 1170 QualType DestType, APSInt &Result) { 1171 unsigned DestWidth = Info.Ctx.getIntWidth(DestType); 1172 // Determine whether we are converting to unsigned or signed. 1173 bool DestSigned = DestType->isSignedIntegerOrEnumerationType(); 1174 1175 Result = APSInt(DestWidth, !DestSigned); 1176 bool ignored; 1177 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored) 1178 & APFloat::opInvalidOp) 1179 HandleOverflow(Info, E, Value, DestType); 1180 return true; 1181 } 1182 1183 static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E, 1184 QualType SrcType, QualType DestType, 1185 APFloat &Result) { 1186 APFloat Value = Result; 1187 bool ignored; 1188 if (Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), 1189 APFloat::rmNearestTiesToEven, &ignored) 1190 & APFloat::opOverflow) 1191 HandleOverflow(Info, E, Value, DestType); 1192 return true; 1193 } 1194 1195 static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E, 1196 QualType DestType, QualType SrcType, 1197 APSInt &Value) { 1198 unsigned DestWidth = Info.Ctx.getIntWidth(DestType); 1199 APSInt Result = Value; 1200 // Figure out if this is a truncate, extend or noop cast. 1201 // If the input is signed, do a sign extend, noop, or truncate. 1202 Result = Result.extOrTrunc(DestWidth); 1203 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType()); 1204 return Result; 1205 } 1206 1207 static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E, 1208 QualType SrcType, const APSInt &Value, 1209 QualType DestType, APFloat &Result) { 1210 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1); 1211 if (Result.convertFromAPInt(Value, Value.isSigned(), 1212 APFloat::rmNearestTiesToEven) 1213 & APFloat::opOverflow) 1214 HandleOverflow(Info, E, Value, DestType); 1215 return true; 1216 } 1217 1218 static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E, 1219 llvm::APInt &Res) { 1220 APValue SVal; 1221 if (!Evaluate(SVal, Info, E)) 1222 return false; 1223 if (SVal.isInt()) { 1224 Res = SVal.getInt(); 1225 return true; 1226 } 1227 if (SVal.isFloat()) { 1228 Res = SVal.getFloat().bitcastToAPInt(); 1229 return true; 1230 } 1231 if (SVal.isVector()) { 1232 QualType VecTy = E->getType(); 1233 unsigned VecSize = Info.Ctx.getTypeSize(VecTy); 1234 QualType EltTy = VecTy->castAs<VectorType>()->getElementType(); 1235 unsigned EltSize = Info.Ctx.getTypeSize(EltTy); 1236 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); 1237 Res = llvm::APInt::getNullValue(VecSize); 1238 for (unsigned i = 0; i < SVal.getVectorLength(); i++) { 1239 APValue &Elt = SVal.getVectorElt(i); 1240 llvm::APInt EltAsInt; 1241 if (Elt.isInt()) { 1242 EltAsInt = Elt.getInt(); 1243 } else if (Elt.isFloat()) { 1244 EltAsInt = Elt.getFloat().bitcastToAPInt(); 1245 } else { 1246 // Don't try to handle vectors of anything other than int or float 1247 // (not sure if it's possible to hit this case). 1248 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1249 return false; 1250 } 1251 unsigned BaseEltSize = EltAsInt.getBitWidth(); 1252 if (BigEndian) 1253 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize); 1254 else 1255 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize); 1256 } 1257 return true; 1258 } 1259 // Give up if the input isn't an int, float, or vector. For example, we 1260 // reject "(v4i16)(intptr_t)&a". 1261 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1262 return false; 1263 } 1264 1265 /// Cast an lvalue referring to a base subobject to a derived class, by 1266 /// truncating the lvalue's path to the given length. 1267 static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result, 1268 const RecordDecl *TruncatedType, 1269 unsigned TruncatedElements) { 1270 SubobjectDesignator &D = Result.Designator; 1271 1272 // Check we actually point to a derived class object. 1273 if (TruncatedElements == D.Entries.size()) 1274 return true; 1275 assert(TruncatedElements >= D.MostDerivedPathLength && 1276 "not casting to a derived class"); 1277 if (!Result.checkSubobject(Info, E, CSK_Derived)) 1278 return false; 1279 1280 // Truncate the path to the subobject, and remove any derived-to-base offsets. 1281 const RecordDecl *RD = TruncatedType; 1282 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) { 1283 if (RD->isInvalidDecl()) return false; 1284 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 1285 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]); 1286 if (isVirtualBaseClass(D.Entries[I])) 1287 Result.Offset -= Layout.getVBaseClassOffset(Base); 1288 else 1289 Result.Offset -= Layout.getBaseClassOffset(Base); 1290 RD = Base; 1291 } 1292 D.Entries.resize(TruncatedElements); 1293 return true; 1294 } 1295 1296 static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj, 1297 const CXXRecordDecl *Derived, 1298 const CXXRecordDecl *Base, 1299 const ASTRecordLayout *RL = 0) { 1300 if (!RL) { 1301 if (Derived->isInvalidDecl()) return false; 1302 RL = &Info.Ctx.getASTRecordLayout(Derived); 1303 } 1304 1305 Obj.getLValueOffset() += RL->getBaseClassOffset(Base); 1306 Obj.addDecl(Info, E, Base, /*Virtual*/ false); 1307 return true; 1308 } 1309 1310 static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj, 1311 const CXXRecordDecl *DerivedDecl, 1312 const CXXBaseSpecifier *Base) { 1313 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl(); 1314 1315 if (!Base->isVirtual()) 1316 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl); 1317 1318 SubobjectDesignator &D = Obj.Designator; 1319 if (D.Invalid) 1320 return false; 1321 1322 // Extract most-derived object and corresponding type. 1323 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl(); 1324 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength)) 1325 return false; 1326 1327 // Find the virtual base class. 1328 if (DerivedDecl->isInvalidDecl()) return false; 1329 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl); 1330 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl); 1331 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true); 1332 return true; 1333 } 1334 1335 /// Update LVal to refer to the given field, which must be a member of the type 1336 /// currently described by LVal. 1337 static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal, 1338 const FieldDecl *FD, 1339 const ASTRecordLayout *RL = 0) { 1340 if (!RL) { 1341 if (FD->getParent()->isInvalidDecl()) return false; 1342 RL = &Info.Ctx.getASTRecordLayout(FD->getParent()); 1343 } 1344 1345 unsigned I = FD->getFieldIndex(); 1346 LVal.Offset += Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)); 1347 LVal.addDecl(Info, E, FD); 1348 return true; 1349 } 1350 1351 /// Update LVal to refer to the given indirect field. 1352 static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E, 1353 LValue &LVal, 1354 const IndirectFieldDecl *IFD) { 1355 for (IndirectFieldDecl::chain_iterator C = IFD->chain_begin(), 1356 CE = IFD->chain_end(); C != CE; ++C) 1357 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(*C))) 1358 return false; 1359 return true; 1360 } 1361 1362 /// Get the size of the given type in char units. 1363 static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc, 1364 QualType Type, CharUnits &Size) { 1365 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc 1366 // extension. 1367 if (Type->isVoidType() || Type->isFunctionType()) { 1368 Size = CharUnits::One(); 1369 return true; 1370 } 1371 1372 if (!Type->isConstantSizeType()) { 1373 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2. 1374 // FIXME: Better diagnostic. 1375 Info.Diag(Loc); 1376 return false; 1377 } 1378 1379 Size = Info.Ctx.getTypeSizeInChars(Type); 1380 return true; 1381 } 1382 1383 /// Update a pointer value to model pointer arithmetic. 1384 /// \param Info - Information about the ongoing evaluation. 1385 /// \param E - The expression being evaluated, for diagnostic purposes. 1386 /// \param LVal - The pointer value to be updated. 1387 /// \param EltTy - The pointee type represented by LVal. 1388 /// \param Adjustment - The adjustment, in objects of type EltTy, to add. 1389 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, 1390 LValue &LVal, QualType EltTy, 1391 int64_t Adjustment) { 1392 CharUnits SizeOfPointee; 1393 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee)) 1394 return false; 1395 1396 // Compute the new offset in the appropriate width. 1397 LVal.Offset += Adjustment * SizeOfPointee; 1398 LVal.adjustIndex(Info, E, Adjustment); 1399 return true; 1400 } 1401 1402 /// Update an lvalue to refer to a component of a complex number. 1403 /// \param Info - Information about the ongoing evaluation. 1404 /// \param LVal - The lvalue to be updated. 1405 /// \param EltTy - The complex number's component type. 1406 /// \param Imag - False for the real component, true for the imaginary. 1407 static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E, 1408 LValue &LVal, QualType EltTy, 1409 bool Imag) { 1410 if (Imag) { 1411 CharUnits SizeOfComponent; 1412 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent)) 1413 return false; 1414 LVal.Offset += SizeOfComponent; 1415 } 1416 LVal.addComplex(Info, E, EltTy, Imag); 1417 return true; 1418 } 1419 1420 /// Try to evaluate the initializer for a variable declaration. 1421 static bool EvaluateVarDeclInit(EvalInfo &Info, const Expr *E, 1422 const VarDecl *VD, 1423 CallStackFrame *Frame, APValue &Result) { 1424 // If this is a parameter to an active constexpr function call, perform 1425 // argument substitution. 1426 if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) { 1427 // Assume arguments of a potential constant expression are unknown 1428 // constant expressions. 1429 if (Info.CheckingPotentialConstantExpression) 1430 return false; 1431 if (!Frame || !Frame->Arguments) { 1432 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1433 return false; 1434 } 1435 Result = Frame->Arguments[PVD->getFunctionScopeIndex()]; 1436 return true; 1437 } 1438 1439 // Dig out the initializer, and use the declaration which it's attached to. 1440 const Expr *Init = VD->getAnyInitializer(VD); 1441 if (!Init || Init->isValueDependent()) { 1442 // If we're checking a potential constant expression, the variable could be 1443 // initialized later. 1444 if (!Info.CheckingPotentialConstantExpression) 1445 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1446 return false; 1447 } 1448 1449 // If we're currently evaluating the initializer of this declaration, use that 1450 // in-flight value. 1451 if (Info.EvaluatingDecl == VD) { 1452 Result = *Info.EvaluatingDeclValue; 1453 return !Result.isUninit(); 1454 } 1455 1456 // Never evaluate the initializer of a weak variable. We can't be sure that 1457 // this is the definition which will be used. 1458 if (VD->isWeak()) { 1459 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1460 return false; 1461 } 1462 1463 // Check that we can fold the initializer. In C++, we will have already done 1464 // this in the cases where it matters for conformance. 1465 llvm::SmallVector<PartialDiagnosticAt, 8> Notes; 1466 if (!VD->evaluateValue(Notes)) { 1467 Info.Diag(E, diag::note_constexpr_var_init_non_constant, 1468 Notes.size() + 1) << VD; 1469 Info.Note(VD->getLocation(), diag::note_declared_at); 1470 Info.addNotes(Notes); 1471 return false; 1472 } else if (!VD->checkInitIsICE()) { 1473 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1474 Notes.size() + 1) << VD; 1475 Info.Note(VD->getLocation(), diag::note_declared_at); 1476 Info.addNotes(Notes); 1477 } 1478 1479 Result = *VD->getEvaluatedValue(); 1480 return true; 1481 } 1482 1483 static bool IsConstNonVolatile(QualType T) { 1484 Qualifiers Quals = T.getQualifiers(); 1485 return Quals.hasConst() && !Quals.hasVolatile(); 1486 } 1487 1488 /// Get the base index of the given base class within an APValue representing 1489 /// the given derived class. 1490 static unsigned getBaseIndex(const CXXRecordDecl *Derived, 1491 const CXXRecordDecl *Base) { 1492 Base = Base->getCanonicalDecl(); 1493 unsigned Index = 0; 1494 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(), 1495 E = Derived->bases_end(); I != E; ++I, ++Index) { 1496 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base) 1497 return Index; 1498 } 1499 1500 llvm_unreachable("base class missing from derived class's bases list"); 1501 } 1502 1503 /// Extract the value of a character from a string literal. CharType is used to 1504 /// determine the expected signedness of the result -- a string literal used to 1505 /// initialize an array of 'signed char' or 'unsigned char' might contain chars 1506 /// of the wrong signedness. 1507 static APSInt ExtractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit, 1508 uint64_t Index, QualType CharType) { 1509 // FIXME: Support PredefinedExpr, ObjCEncodeExpr, MakeStringConstant 1510 const StringLiteral *S = dyn_cast<StringLiteral>(Lit); 1511 assert(S && "unexpected string literal expression kind"); 1512 assert(CharType->isIntegerType() && "unexpected character type"); 1513 1514 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), 1515 CharType->isUnsignedIntegerType()); 1516 if (Index < S->getLength()) 1517 Value = S->getCodeUnit(Index); 1518 return Value; 1519 } 1520 1521 /// Extract the designated sub-object of an rvalue. 1522 static bool ExtractSubobject(EvalInfo &Info, const Expr *E, 1523 APValue &Obj, QualType ObjType, 1524 const SubobjectDesignator &Sub, QualType SubType) { 1525 if (Sub.Invalid) 1526 // A diagnostic will have already been produced. 1527 return false; 1528 if (Sub.isOnePastTheEnd()) { 1529 Info.Diag(E, Info.getLangOpts().CPlusPlus0x ? 1530 (unsigned)diag::note_constexpr_read_past_end : 1531 (unsigned)diag::note_invalid_subexpr_in_const_expr); 1532 return false; 1533 } 1534 if (Sub.Entries.empty()) 1535 return true; 1536 if (Info.CheckingPotentialConstantExpression && Obj.isUninit()) 1537 // This object might be initialized later. 1538 return false; 1539 1540 APValue *O = &Obj; 1541 // Walk the designator's path to find the subobject. 1542 for (unsigned I = 0, N = Sub.Entries.size(); I != N; ++I) { 1543 if (ObjType->isArrayType()) { 1544 // Next subobject is an array element. 1545 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType); 1546 assert(CAT && "vla in literal type?"); 1547 uint64_t Index = Sub.Entries[I].ArrayIndex; 1548 if (CAT->getSize().ule(Index)) { 1549 // Note, it should not be possible to form a pointer with a valid 1550 // designator which points more than one past the end of the array. 1551 Info.Diag(E, Info.getLangOpts().CPlusPlus0x ? 1552 (unsigned)diag::note_constexpr_read_past_end : 1553 (unsigned)diag::note_invalid_subexpr_in_const_expr); 1554 return false; 1555 } 1556 // An array object is represented as either an Array APValue or as an 1557 // LValue which refers to a string literal. 1558 if (O->isLValue()) { 1559 assert(I == N - 1 && "extracting subobject of character?"); 1560 assert(!O->hasLValuePath() || O->getLValuePath().empty()); 1561 Obj = APValue(ExtractStringLiteralCharacter( 1562 Info, O->getLValueBase().get<const Expr*>(), Index, SubType)); 1563 return true; 1564 } else if (O->getArrayInitializedElts() > Index) 1565 O = &O->getArrayInitializedElt(Index); 1566 else 1567 O = &O->getArrayFiller(); 1568 ObjType = CAT->getElementType(); 1569 } else if (ObjType->isAnyComplexType()) { 1570 // Next subobject is a complex number. 1571 uint64_t Index = Sub.Entries[I].ArrayIndex; 1572 if (Index > 1) { 1573 Info.Diag(E, Info.getLangOpts().CPlusPlus0x ? 1574 (unsigned)diag::note_constexpr_read_past_end : 1575 (unsigned)diag::note_invalid_subexpr_in_const_expr); 1576 return false; 1577 } 1578 assert(I == N - 1 && "extracting subobject of scalar?"); 1579 if (O->isComplexInt()) { 1580 Obj = APValue(Index ? O->getComplexIntImag() 1581 : O->getComplexIntReal()); 1582 } else { 1583 assert(O->isComplexFloat()); 1584 Obj = APValue(Index ? O->getComplexFloatImag() 1585 : O->getComplexFloatReal()); 1586 } 1587 return true; 1588 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) { 1589 if (Field->isMutable()) { 1590 Info.Diag(E, diag::note_constexpr_ltor_mutable, 1) 1591 << Field; 1592 Info.Note(Field->getLocation(), diag::note_declared_at); 1593 return false; 1594 } 1595 1596 // Next subobject is a class, struct or union field. 1597 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl(); 1598 if (RD->isUnion()) { 1599 const FieldDecl *UnionField = O->getUnionField(); 1600 if (!UnionField || 1601 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) { 1602 Info.Diag(E, diag::note_constexpr_read_inactive_union_member) 1603 << Field << !UnionField << UnionField; 1604 return false; 1605 } 1606 O = &O->getUnionValue(); 1607 } else 1608 O = &O->getStructField(Field->getFieldIndex()); 1609 ObjType = Field->getType(); 1610 1611 if (ObjType.isVolatileQualified()) { 1612 if (Info.getLangOpts().CPlusPlus) { 1613 // FIXME: Include a description of the path to the volatile subobject. 1614 Info.Diag(E, diag::note_constexpr_ltor_volatile_obj, 1) 1615 << 2 << Field; 1616 Info.Note(Field->getLocation(), diag::note_declared_at); 1617 } else { 1618 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1619 } 1620 return false; 1621 } 1622 } else { 1623 // Next subobject is a base class. 1624 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl(); 1625 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]); 1626 O = &O->getStructBase(getBaseIndex(Derived, Base)); 1627 ObjType = Info.Ctx.getRecordType(Base); 1628 } 1629 1630 if (O->isUninit()) { 1631 if (!Info.CheckingPotentialConstantExpression) 1632 Info.Diag(E, diag::note_constexpr_read_uninit); 1633 return false; 1634 } 1635 } 1636 1637 // This may look super-stupid, but it serves an important purpose: if we just 1638 // swapped Obj and *O, we'd create an object which had itself as a subobject. 1639 // To avoid the leak, we ensure that Tmp ends up owning the original complete 1640 // object, which is destroyed by Tmp's destructor. 1641 APValue Tmp; 1642 O->swap(Tmp); 1643 Obj.swap(Tmp); 1644 return true; 1645 } 1646 1647 /// Find the position where two subobject designators diverge, or equivalently 1648 /// the length of the common initial subsequence. 1649 static unsigned FindDesignatorMismatch(QualType ObjType, 1650 const SubobjectDesignator &A, 1651 const SubobjectDesignator &B, 1652 bool &WasArrayIndex) { 1653 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size()); 1654 for (/**/; I != N; ++I) { 1655 if (!ObjType.isNull() && 1656 (ObjType->isArrayType() || ObjType->isAnyComplexType())) { 1657 // Next subobject is an array element. 1658 if (A.Entries[I].ArrayIndex != B.Entries[I].ArrayIndex) { 1659 WasArrayIndex = true; 1660 return I; 1661 } 1662 if (ObjType->isAnyComplexType()) 1663 ObjType = ObjType->castAs<ComplexType>()->getElementType(); 1664 else 1665 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType(); 1666 } else { 1667 if (A.Entries[I].BaseOrMember != B.Entries[I].BaseOrMember) { 1668 WasArrayIndex = false; 1669 return I; 1670 } 1671 if (const FieldDecl *FD = getAsField(A.Entries[I])) 1672 // Next subobject is a field. 1673 ObjType = FD->getType(); 1674 else 1675 // Next subobject is a base class. 1676 ObjType = QualType(); 1677 } 1678 } 1679 WasArrayIndex = false; 1680 return I; 1681 } 1682 1683 /// Determine whether the given subobject designators refer to elements of the 1684 /// same array object. 1685 static bool AreElementsOfSameArray(QualType ObjType, 1686 const SubobjectDesignator &A, 1687 const SubobjectDesignator &B) { 1688 if (A.Entries.size() != B.Entries.size()) 1689 return false; 1690 1691 bool IsArray = A.MostDerivedArraySize != 0; 1692 if (IsArray && A.MostDerivedPathLength != A.Entries.size()) 1693 // A is a subobject of the array element. 1694 return false; 1695 1696 // If A (and B) designates an array element, the last entry will be the array 1697 // index. That doesn't have to match. Otherwise, we're in the 'implicit array 1698 // of length 1' case, and the entire path must match. 1699 bool WasArrayIndex; 1700 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex); 1701 return CommonLength >= A.Entries.size() - IsArray; 1702 } 1703 1704 /// HandleLValueToRValueConversion - Perform an lvalue-to-rvalue conversion on 1705 /// the given lvalue. This can also be used for 'lvalue-to-lvalue' conversions 1706 /// for looking up the glvalue referred to by an entity of reference type. 1707 /// 1708 /// \param Info - Information about the ongoing evaluation. 1709 /// \param Conv - The expression for which we are performing the conversion. 1710 /// Used for diagnostics. 1711 /// \param Type - The type we expect this conversion to produce, before 1712 /// stripping cv-qualifiers in the case of a non-clas type. 1713 /// \param LVal - The glvalue on which we are attempting to perform this action. 1714 /// \param RVal - The produced value will be placed here. 1715 static bool HandleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, 1716 QualType Type, 1717 const LValue &LVal, APValue &RVal) { 1718 if (LVal.Designator.Invalid) 1719 // A diagnostic will have already been produced. 1720 return false; 1721 1722 const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); 1723 1724 if (!LVal.Base) { 1725 // FIXME: Indirection through a null pointer deserves a specific diagnostic. 1726 Info.Diag(Conv, diag::note_invalid_subexpr_in_const_expr); 1727 return false; 1728 } 1729 1730 CallStackFrame *Frame = 0; 1731 if (LVal.CallIndex) { 1732 Frame = Info.getCallFrame(LVal.CallIndex); 1733 if (!Frame) { 1734 Info.Diag(Conv, diag::note_constexpr_lifetime_ended, 1) << !Base; 1735 NoteLValueLocation(Info, LVal.Base); 1736 return false; 1737 } 1738 } 1739 1740 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type 1741 // is not a constant expression (even if the object is non-volatile). We also 1742 // apply this rule to C++98, in order to conform to the expected 'volatile' 1743 // semantics. 1744 if (Type.isVolatileQualified()) { 1745 if (Info.getLangOpts().CPlusPlus) 1746 Info.Diag(Conv, diag::note_constexpr_ltor_volatile_type) << Type; 1747 else 1748 Info.Diag(Conv); 1749 return false; 1750 } 1751 1752 if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl*>()) { 1753 // In C++98, const, non-volatile integers initialized with ICEs are ICEs. 1754 // In C++11, constexpr, non-volatile variables initialized with constant 1755 // expressions are constant expressions too. Inside constexpr functions, 1756 // parameters are constant expressions even if they're non-const. 1757 // In C, such things can also be folded, although they are not ICEs. 1758 const VarDecl *VD = dyn_cast<VarDecl>(D); 1759 if (VD) { 1760 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx)) 1761 VD = VDef; 1762 } 1763 if (!VD || VD->isInvalidDecl()) { 1764 Info.Diag(Conv); 1765 return false; 1766 } 1767 1768 // DR1313: If the object is volatile-qualified but the glvalue was not, 1769 // behavior is undefined so the result is not a constant expression. 1770 QualType VT = VD->getType(); 1771 if (VT.isVolatileQualified()) { 1772 if (Info.getLangOpts().CPlusPlus) { 1773 Info.Diag(Conv, diag::note_constexpr_ltor_volatile_obj, 1) << 1 << VD; 1774 Info.Note(VD->getLocation(), diag::note_declared_at); 1775 } else { 1776 Info.Diag(Conv); 1777 } 1778 return false; 1779 } 1780 1781 if (!isa<ParmVarDecl>(VD)) { 1782 if (VD->isConstexpr()) { 1783 // OK, we can read this variable. 1784 } else if (VT->isIntegralOrEnumerationType()) { 1785 if (!VT.isConstQualified()) { 1786 if (Info.getLangOpts().CPlusPlus) { 1787 Info.Diag(Conv, diag::note_constexpr_ltor_non_const_int, 1) << VD; 1788 Info.Note(VD->getLocation(), diag::note_declared_at); 1789 } else { 1790 Info.Diag(Conv); 1791 } 1792 return false; 1793 } 1794 } else if (VT->isFloatingType() && VT.isConstQualified()) { 1795 // We support folding of const floating-point types, in order to make 1796 // static const data members of such types (supported as an extension) 1797 // more useful. 1798 if (Info.getLangOpts().CPlusPlus0x) { 1799 Info.CCEDiag(Conv, diag::note_constexpr_ltor_non_constexpr, 1) << VD; 1800 Info.Note(VD->getLocation(), diag::note_declared_at); 1801 } else { 1802 Info.CCEDiag(Conv); 1803 } 1804 } else { 1805 // FIXME: Allow folding of values of any literal type in all languages. 1806 if (Info.getLangOpts().CPlusPlus0x) { 1807 Info.Diag(Conv, diag::note_constexpr_ltor_non_constexpr, 1) << VD; 1808 Info.Note(VD->getLocation(), diag::note_declared_at); 1809 } else { 1810 Info.Diag(Conv); 1811 } 1812 return false; 1813 } 1814 } 1815 1816 if (!EvaluateVarDeclInit(Info, Conv, VD, Frame, RVal)) 1817 return false; 1818 1819 if (isa<ParmVarDecl>(VD) || !VD->getAnyInitializer()->isLValue()) 1820 return ExtractSubobject(Info, Conv, RVal, VT, LVal.Designator, Type); 1821 1822 // The declaration was initialized by an lvalue, with no lvalue-to-rvalue 1823 // conversion. This happens when the declaration and the lvalue should be 1824 // considered synonymous, for instance when initializing an array of char 1825 // from a string literal. Continue as if the initializer lvalue was the 1826 // value we were originally given. 1827 assert(RVal.getLValueOffset().isZero() && 1828 "offset for lvalue init of non-reference"); 1829 Base = RVal.getLValueBase().get<const Expr*>(); 1830 1831 if (unsigned CallIndex = RVal.getLValueCallIndex()) { 1832 Frame = Info.getCallFrame(CallIndex); 1833 if (!Frame) { 1834 Info.Diag(Conv, diag::note_constexpr_lifetime_ended, 1) << !Base; 1835 NoteLValueLocation(Info, RVal.getLValueBase()); 1836 return false; 1837 } 1838 } else { 1839 Frame = 0; 1840 } 1841 } 1842 1843 // Volatile temporary objects cannot be read in constant expressions. 1844 if (Base->getType().isVolatileQualified()) { 1845 if (Info.getLangOpts().CPlusPlus) { 1846 Info.Diag(Conv, diag::note_constexpr_ltor_volatile_obj, 1) << 0; 1847 Info.Note(Base->getExprLoc(), diag::note_constexpr_temporary_here); 1848 } else { 1849 Info.Diag(Conv); 1850 } 1851 return false; 1852 } 1853 1854 if (Frame) { 1855 // If this is a temporary expression with a nontrivial initializer, grab the 1856 // value from the relevant stack frame. 1857 RVal = Frame->Temporaries[Base]; 1858 } else if (const CompoundLiteralExpr *CLE 1859 = dyn_cast<CompoundLiteralExpr>(Base)) { 1860 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the 1861 // initializer until now for such expressions. Such an expression can't be 1862 // an ICE in C, so this only matters for fold. 1863 assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?"); 1864 if (!Evaluate(RVal, Info, CLE->getInitializer())) 1865 return false; 1866 } else if (isa<StringLiteral>(Base)) { 1867 // We represent a string literal array as an lvalue pointing at the 1868 // corresponding expression, rather than building an array of chars. 1869 // FIXME: Support PredefinedExpr, ObjCEncodeExpr, MakeStringConstant 1870 RVal = APValue(Base, CharUnits::Zero(), APValue::NoLValuePath(), 0); 1871 } else { 1872 Info.Diag(Conv, diag::note_invalid_subexpr_in_const_expr); 1873 return false; 1874 } 1875 1876 return ExtractSubobject(Info, Conv, RVal, Base->getType(), LVal.Designator, 1877 Type); 1878 } 1879 1880 /// Build an lvalue for the object argument of a member function call. 1881 static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object, 1882 LValue &This) { 1883 if (Object->getType()->isPointerType()) 1884 return EvaluatePointer(Object, This, Info); 1885 1886 if (Object->isGLValue()) 1887 return EvaluateLValue(Object, This, Info); 1888 1889 if (Object->getType()->isLiteralType()) 1890 return EvaluateTemporary(Object, This, Info); 1891 1892 return false; 1893 } 1894 1895 /// HandleMemberPointerAccess - Evaluate a member access operation and build an 1896 /// lvalue referring to the result. 1897 /// 1898 /// \param Info - Information about the ongoing evaluation. 1899 /// \param BO - The member pointer access operation. 1900 /// \param LV - Filled in with a reference to the resulting object. 1901 /// \param IncludeMember - Specifies whether the member itself is included in 1902 /// the resulting LValue subobject designator. This is not possible when 1903 /// creating a bound member function. 1904 /// \return The field or method declaration to which the member pointer refers, 1905 /// or 0 if evaluation fails. 1906 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, 1907 const BinaryOperator *BO, 1908 LValue &LV, 1909 bool IncludeMember = true) { 1910 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI); 1911 1912 bool EvalObjOK = EvaluateObjectArgument(Info, BO->getLHS(), LV); 1913 if (!EvalObjOK && !Info.keepEvaluatingAfterFailure()) 1914 return 0; 1915 1916 MemberPtr MemPtr; 1917 if (!EvaluateMemberPointer(BO->getRHS(), MemPtr, Info)) 1918 return 0; 1919 1920 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to 1921 // member value, the behavior is undefined. 1922 if (!MemPtr.getDecl()) 1923 return 0; 1924 1925 if (!EvalObjOK) 1926 return 0; 1927 1928 if (MemPtr.isDerivedMember()) { 1929 // This is a member of some derived class. Truncate LV appropriately. 1930 // The end of the derived-to-base path for the base object must match the 1931 // derived-to-base path for the member pointer. 1932 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() > 1933 LV.Designator.Entries.size()) 1934 return 0; 1935 unsigned PathLengthToMember = 1936 LV.Designator.Entries.size() - MemPtr.Path.size(); 1937 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) { 1938 const CXXRecordDecl *LVDecl = getAsBaseClass( 1939 LV.Designator.Entries[PathLengthToMember + I]); 1940 const CXXRecordDecl *MPDecl = MemPtr.Path[I]; 1941 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) 1942 return 0; 1943 } 1944 1945 // Truncate the lvalue to the appropriate derived class. 1946 if (!CastToDerivedClass(Info, BO, LV, MemPtr.getContainingRecord(), 1947 PathLengthToMember)) 1948 return 0; 1949 } else if (!MemPtr.Path.empty()) { 1950 // Extend the LValue path with the member pointer's path. 1951 LV.Designator.Entries.reserve(LV.Designator.Entries.size() + 1952 MemPtr.Path.size() + IncludeMember); 1953 1954 // Walk down to the appropriate base class. 1955 QualType LVType = BO->getLHS()->getType(); 1956 if (const PointerType *PT = LVType->getAs<PointerType>()) 1957 LVType = PT->getPointeeType(); 1958 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl(); 1959 assert(RD && "member pointer access on non-class-type expression"); 1960 // The first class in the path is that of the lvalue. 1961 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) { 1962 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1]; 1963 if (!HandleLValueDirectBase(Info, BO, LV, RD, Base)) 1964 return 0; 1965 RD = Base; 1966 } 1967 // Finally cast to the class containing the member. 1968 if (!HandleLValueDirectBase(Info, BO, LV, RD, MemPtr.getContainingRecord())) 1969 return 0; 1970 } 1971 1972 // Add the member. Note that we cannot build bound member functions here. 1973 if (IncludeMember) { 1974 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) { 1975 if (!HandleLValueMember(Info, BO, LV, FD)) 1976 return 0; 1977 } else if (const IndirectFieldDecl *IFD = 1978 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) { 1979 if (!HandleLValueIndirectMember(Info, BO, LV, IFD)) 1980 return 0; 1981 } else { 1982 llvm_unreachable("can't construct reference to bound member function"); 1983 } 1984 } 1985 1986 return MemPtr.getDecl(); 1987 } 1988 1989 /// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on 1990 /// the provided lvalue, which currently refers to the base object. 1991 static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E, 1992 LValue &Result) { 1993 SubobjectDesignator &D = Result.Designator; 1994 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived)) 1995 return false; 1996 1997 QualType TargetQT = E->getType(); 1998 if (const PointerType *PT = TargetQT->getAs<PointerType>()) 1999 TargetQT = PT->getPointeeType(); 2000 2001 // Check this cast lands within the final derived-to-base subobject path. 2002 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) { 2003 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) 2004 << D.MostDerivedType << TargetQT; 2005 return false; 2006 } 2007 2008 // Check the type of the final cast. We don't need to check the path, 2009 // since a cast can only be formed if the path is unique. 2010 unsigned NewEntriesSize = D.Entries.size() - E->path_size(); 2011 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl(); 2012 const CXXRecordDecl *FinalType; 2013 if (NewEntriesSize == D.MostDerivedPathLength) 2014 FinalType = D.MostDerivedType->getAsCXXRecordDecl(); 2015 else 2016 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]); 2017 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) { 2018 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) 2019 << D.MostDerivedType << TargetQT; 2020 return false; 2021 } 2022 2023 // Truncate the lvalue to the appropriate derived class. 2024 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize); 2025 } 2026 2027 namespace { 2028 enum EvalStmtResult { 2029 /// Evaluation failed. 2030 ESR_Failed, 2031 /// Hit a 'return' statement. 2032 ESR_Returned, 2033 /// Evaluation succeeded. 2034 ESR_Succeeded 2035 }; 2036 } 2037 2038 // Evaluate a statement. 2039 static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info, 2040 const Stmt *S) { 2041 switch (S->getStmtClass()) { 2042 default: 2043 return ESR_Failed; 2044 2045 case Stmt::NullStmtClass: 2046 case Stmt::DeclStmtClass: 2047 return ESR_Succeeded; 2048 2049 case Stmt::ReturnStmtClass: { 2050 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue(); 2051 if (!Evaluate(Result, Info, RetExpr)) 2052 return ESR_Failed; 2053 return ESR_Returned; 2054 } 2055 2056 case Stmt::CompoundStmtClass: { 2057 const CompoundStmt *CS = cast<CompoundStmt>(S); 2058 for (CompoundStmt::const_body_iterator BI = CS->body_begin(), 2059 BE = CS->body_end(); BI != BE; ++BI) { 2060 EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI); 2061 if (ESR != ESR_Succeeded) 2062 return ESR; 2063 } 2064 return ESR_Succeeded; 2065 } 2066 } 2067 } 2068 2069 /// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial 2070 /// default constructor. If so, we'll fold it whether or not it's marked as 2071 /// constexpr. If it is marked as constexpr, we will never implicitly define it, 2072 /// so we need special handling. 2073 static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc, 2074 const CXXConstructorDecl *CD, 2075 bool IsValueInitialization) { 2076 if (!CD->isTrivial() || !CD->isDefaultConstructor()) 2077 return false; 2078 2079 // Value-initialization does not call a trivial default constructor, so such a 2080 // call is a core constant expression whether or not the constructor is 2081 // constexpr. 2082 if (!CD->isConstexpr() && !IsValueInitialization) { 2083 if (Info.getLangOpts().CPlusPlus0x) { 2084 // FIXME: If DiagDecl is an implicitly-declared special member function, 2085 // we should be much more explicit about why it's not constexpr. 2086 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1) 2087 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD; 2088 Info.Note(CD->getLocation(), diag::note_declared_at); 2089 } else { 2090 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr); 2091 } 2092 } 2093 return true; 2094 } 2095 2096 /// CheckConstexprFunction - Check that a function can be called in a constant 2097 /// expression. 2098 static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc, 2099 const FunctionDecl *Declaration, 2100 const FunctionDecl *Definition) { 2101 // Potential constant expressions can contain calls to declared, but not yet 2102 // defined, constexpr functions. 2103 if (Info.CheckingPotentialConstantExpression && !Definition && 2104 Declaration->isConstexpr()) 2105 return false; 2106 2107 // Can we evaluate this function call? 2108 if (Definition && Definition->isConstexpr() && !Definition->isInvalidDecl()) 2109 return true; 2110 2111 if (Info.getLangOpts().CPlusPlus0x) { 2112 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration; 2113 // FIXME: If DiagDecl is an implicitly-declared special member function, we 2114 // should be much more explicit about why it's not constexpr. 2115 Info.Diag(CallLoc, diag::note_constexpr_invalid_function, 1) 2116 << DiagDecl->isConstexpr() << isa<CXXConstructorDecl>(DiagDecl) 2117 << DiagDecl; 2118 Info.Note(DiagDecl->getLocation(), diag::note_declared_at); 2119 } else { 2120 Info.Diag(CallLoc, diag::note_invalid_subexpr_in_const_expr); 2121 } 2122 return false; 2123 } 2124 2125 namespace { 2126 typedef SmallVector<APValue, 8> ArgVector; 2127 } 2128 2129 /// EvaluateArgs - Evaluate the arguments to a function call. 2130 static bool EvaluateArgs(ArrayRef<const Expr*> Args, ArgVector &ArgValues, 2131 EvalInfo &Info) { 2132 bool Success = true; 2133 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end(); 2134 I != E; ++I) { 2135 if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) { 2136 // If we're checking for a potential constant expression, evaluate all 2137 // initializers even if some of them fail. 2138 if (!Info.keepEvaluatingAfterFailure()) 2139 return false; 2140 Success = false; 2141 } 2142 } 2143 return Success; 2144 } 2145 2146 /// Evaluate a function call. 2147 static bool HandleFunctionCall(SourceLocation CallLoc, 2148 const FunctionDecl *Callee, const LValue *This, 2149 ArrayRef<const Expr*> Args, const Stmt *Body, 2150 EvalInfo &Info, APValue &Result) { 2151 ArgVector ArgValues(Args.size()); 2152 if (!EvaluateArgs(Args, ArgValues, Info)) 2153 return false; 2154 2155 if (!Info.CheckCallLimit(CallLoc)) 2156 return false; 2157 2158 CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data()); 2159 return EvaluateStmt(Result, Info, Body) == ESR_Returned; 2160 } 2161 2162 /// Evaluate a constructor call. 2163 static bool HandleConstructorCall(SourceLocation CallLoc, const LValue &This, 2164 ArrayRef<const Expr*> Args, 2165 const CXXConstructorDecl *Definition, 2166 EvalInfo &Info, APValue &Result) { 2167 ArgVector ArgValues(Args.size()); 2168 if (!EvaluateArgs(Args, ArgValues, Info)) 2169 return false; 2170 2171 if (!Info.CheckCallLimit(CallLoc)) 2172 return false; 2173 2174 const CXXRecordDecl *RD = Definition->getParent(); 2175 if (RD->getNumVBases()) { 2176 Info.Diag(CallLoc, diag::note_constexpr_virtual_base) << RD; 2177 return false; 2178 } 2179 2180 CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues.data()); 2181 2182 // If it's a delegating constructor, just delegate. 2183 if (Definition->isDelegatingConstructor()) { 2184 CXXConstructorDecl::init_const_iterator I = Definition->init_begin(); 2185 return EvaluateInPlace(Result, Info, This, (*I)->getInit()); 2186 } 2187 2188 // For a trivial copy or move constructor, perform an APValue copy. This is 2189 // essential for unions, where the operations performed by the constructor 2190 // cannot be represented by ctor-initializers. 2191 if (Definition->isDefaulted() && 2192 ((Definition->isCopyConstructor() && Definition->isTrivial()) || 2193 (Definition->isMoveConstructor() && Definition->isTrivial()))) { 2194 LValue RHS; 2195 RHS.setFrom(Info.Ctx, ArgValues[0]); 2196 return HandleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), 2197 RHS, Result); 2198 } 2199 2200 // Reserve space for the struct members. 2201 if (!RD->isUnion() && Result.isUninit()) 2202 Result = APValue(APValue::UninitStruct(), RD->getNumBases(), 2203 std::distance(RD->field_begin(), RD->field_end())); 2204 2205 if (RD->isInvalidDecl()) return false; 2206 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 2207 2208 bool Success = true; 2209 unsigned BasesSeen = 0; 2210 #ifndef NDEBUG 2211 CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin(); 2212 #endif 2213 for (CXXConstructorDecl::init_const_iterator I = Definition->init_begin(), 2214 E = Definition->init_end(); I != E; ++I) { 2215 LValue Subobject = This; 2216 APValue *Value = &Result; 2217 2218 // Determine the subobject to initialize. 2219 if ((*I)->isBaseInitializer()) { 2220 QualType BaseType((*I)->getBaseClass(), 0); 2221 #ifndef NDEBUG 2222 // Non-virtual base classes are initialized in the order in the class 2223 // definition. We have already checked for virtual base classes. 2224 assert(!BaseIt->isVirtual() && "virtual base for literal type"); 2225 assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && 2226 "base class initializers not in expected order"); 2227 ++BaseIt; 2228 #endif 2229 if (!HandleLValueDirectBase(Info, (*I)->getInit(), Subobject, RD, 2230 BaseType->getAsCXXRecordDecl(), &Layout)) 2231 return false; 2232 Value = &Result.getStructBase(BasesSeen++); 2233 } else if (FieldDecl *FD = (*I)->getMember()) { 2234 if (!HandleLValueMember(Info, (*I)->getInit(), Subobject, FD, &Layout)) 2235 return false; 2236 if (RD->isUnion()) { 2237 Result = APValue(FD); 2238 Value = &Result.getUnionValue(); 2239 } else { 2240 Value = &Result.getStructField(FD->getFieldIndex()); 2241 } 2242 } else if (IndirectFieldDecl *IFD = (*I)->getIndirectMember()) { 2243 // Walk the indirect field decl's chain to find the object to initialize, 2244 // and make sure we've initialized every step along it. 2245 for (IndirectFieldDecl::chain_iterator C = IFD->chain_begin(), 2246 CE = IFD->chain_end(); 2247 C != CE; ++C) { 2248 FieldDecl *FD = cast<FieldDecl>(*C); 2249 CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent()); 2250 // Switch the union field if it differs. This happens if we had 2251 // preceding zero-initialization, and we're now initializing a union 2252 // subobject other than the first. 2253 // FIXME: In this case, the values of the other subobjects are 2254 // specified, since zero-initialization sets all padding bits to zero. 2255 if (Value->isUninit() || 2256 (Value->isUnion() && Value->getUnionField() != FD)) { 2257 if (CD->isUnion()) 2258 *Value = APValue(FD); 2259 else 2260 *Value = APValue(APValue::UninitStruct(), CD->getNumBases(), 2261 std::distance(CD->field_begin(), CD->field_end())); 2262 } 2263 if (!HandleLValueMember(Info, (*I)->getInit(), Subobject, FD)) 2264 return false; 2265 if (CD->isUnion()) 2266 Value = &Value->getUnionValue(); 2267 else 2268 Value = &Value->getStructField(FD->getFieldIndex()); 2269 } 2270 } else { 2271 llvm_unreachable("unknown base initializer kind"); 2272 } 2273 2274 if (!EvaluateInPlace(*Value, Info, Subobject, (*I)->getInit(), 2275 (*I)->isBaseInitializer() 2276 ? CCEK_Constant : CCEK_MemberInit)) { 2277 // If we're checking for a potential constant expression, evaluate all 2278 // initializers even if some of them fail. 2279 if (!Info.keepEvaluatingAfterFailure()) 2280 return false; 2281 Success = false; 2282 } 2283 } 2284 2285 return Success; 2286 } 2287 2288 //===----------------------------------------------------------------------===// 2289 // Generic Evaluation 2290 //===----------------------------------------------------------------------===// 2291 namespace { 2292 2293 // FIXME: RetTy is always bool. Remove it. 2294 template <class Derived, typename RetTy=bool> 2295 class ExprEvaluatorBase 2296 : public ConstStmtVisitor<Derived, RetTy> { 2297 private: 2298 RetTy DerivedSuccess(const APValue &V, const Expr *E) { 2299 return static_cast<Derived*>(this)->Success(V, E); 2300 } 2301 RetTy DerivedZeroInitialization(const Expr *E) { 2302 return static_cast<Derived*>(this)->ZeroInitialization(E); 2303 } 2304 2305 // Check whether a conditional operator with a non-constant condition is a 2306 // potential constant expression. If neither arm is a potential constant 2307 // expression, then the conditional operator is not either. 2308 template<typename ConditionalOperator> 2309 void CheckPotentialConstantConditional(const ConditionalOperator *E) { 2310 assert(Info.CheckingPotentialConstantExpression); 2311 2312 // Speculatively evaluate both arms. 2313 { 2314 llvm::SmallVector<PartialDiagnosticAt, 8> Diag; 2315 SpeculativeEvaluationRAII Speculate(Info, &Diag); 2316 2317 StmtVisitorTy::Visit(E->getFalseExpr()); 2318 if (Diag.empty()) 2319 return; 2320 2321 Diag.clear(); 2322 StmtVisitorTy::Visit(E->getTrueExpr()); 2323 if (Diag.empty()) 2324 return; 2325 } 2326 2327 Error(E, diag::note_constexpr_conditional_never_const); 2328 } 2329 2330 2331 template<typename ConditionalOperator> 2332 bool HandleConditionalOperator(const ConditionalOperator *E) { 2333 bool BoolResult; 2334 if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) { 2335 if (Info.CheckingPotentialConstantExpression) 2336 CheckPotentialConstantConditional(E); 2337 return false; 2338 } 2339 2340 Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr(); 2341 return StmtVisitorTy::Visit(EvalExpr); 2342 } 2343 2344 protected: 2345 EvalInfo &Info; 2346 typedef ConstStmtVisitor<Derived, RetTy> StmtVisitorTy; 2347 typedef ExprEvaluatorBase ExprEvaluatorBaseTy; 2348 2349 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { 2350 return Info.CCEDiag(E, D); 2351 } 2352 2353 RetTy ZeroInitialization(const Expr *E) { return Error(E); } 2354 2355 public: 2356 ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {} 2357 2358 EvalInfo &getEvalInfo() { return Info; } 2359 2360 /// Report an evaluation error. This should only be called when an error is 2361 /// first discovered. When propagating an error, just return false. 2362 bool Error(const Expr *E, diag::kind D) { 2363 Info.Diag(E, D); 2364 return false; 2365 } 2366 bool Error(const Expr *E) { 2367 return Error(E, diag::note_invalid_subexpr_in_const_expr); 2368 } 2369 2370 RetTy VisitStmt(const Stmt *) { 2371 llvm_unreachable("Expression evaluator should not be called on stmts"); 2372 } 2373 RetTy VisitExpr(const Expr *E) { 2374 return Error(E); 2375 } 2376 2377 RetTy VisitParenExpr(const ParenExpr *E) 2378 { return StmtVisitorTy::Visit(E->getSubExpr()); } 2379 RetTy VisitUnaryExtension(const UnaryOperator *E) 2380 { return StmtVisitorTy::Visit(E->getSubExpr()); } 2381 RetTy VisitUnaryPlus(const UnaryOperator *E) 2382 { return StmtVisitorTy::Visit(E->getSubExpr()); } 2383 RetTy VisitChooseExpr(const ChooseExpr *E) 2384 { return StmtVisitorTy::Visit(E->getChosenSubExpr(Info.Ctx)); } 2385 RetTy VisitGenericSelectionExpr(const GenericSelectionExpr *E) 2386 { return StmtVisitorTy::Visit(E->getResultExpr()); } 2387 RetTy VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E) 2388 { return StmtVisitorTy::Visit(E->getReplacement()); } 2389 RetTy VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) 2390 { return StmtVisitorTy::Visit(E->getExpr()); } 2391 // We cannot create any objects for which cleanups are required, so there is 2392 // nothing to do here; all cleanups must come from unevaluated subexpressions. 2393 RetTy VisitExprWithCleanups(const ExprWithCleanups *E) 2394 { return StmtVisitorTy::Visit(E->getSubExpr()); } 2395 2396 RetTy VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) { 2397 CCEDiag(E, diag::note_constexpr_invalid_cast) << 0; 2398 return static_cast<Derived*>(this)->VisitCastExpr(E); 2399 } 2400 RetTy VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) { 2401 CCEDiag(E, diag::note_constexpr_invalid_cast) << 1; 2402 return static_cast<Derived*>(this)->VisitCastExpr(E); 2403 } 2404 2405 RetTy VisitBinaryOperator(const BinaryOperator *E) { 2406 switch (E->getOpcode()) { 2407 default: 2408 return Error(E); 2409 2410 case BO_Comma: 2411 VisitIgnoredValue(E->getLHS()); 2412 return StmtVisitorTy::Visit(E->getRHS()); 2413 2414 case BO_PtrMemD: 2415 case BO_PtrMemI: { 2416 LValue Obj; 2417 if (!HandleMemberPointerAccess(Info, E, Obj)) 2418 return false; 2419 APValue Result; 2420 if (!HandleLValueToRValueConversion(Info, E, E->getType(), Obj, Result)) 2421 return false; 2422 return DerivedSuccess(Result, E); 2423 } 2424 } 2425 } 2426 2427 RetTy VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) { 2428 // Evaluate and cache the common expression. We treat it as a temporary, 2429 // even though it's not quite the same thing. 2430 if (!Evaluate(Info.CurrentCall->Temporaries[E->getOpaqueValue()], 2431 Info, E->getCommon())) 2432 return false; 2433 2434 return HandleConditionalOperator(E); 2435 } 2436 2437 RetTy VisitConditionalOperator(const ConditionalOperator *E) { 2438 bool IsBcpCall = false; 2439 // If the condition (ignoring parens) is a __builtin_constant_p call, 2440 // the result is a constant expression if it can be folded without 2441 // side-effects. This is an important GNU extension. See GCC PR38377 2442 // for discussion. 2443 if (const CallExpr *CallCE = 2444 dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts())) 2445 if (CallCE->isBuiltinCall() == Builtin::BI__builtin_constant_p) 2446 IsBcpCall = true; 2447 2448 // Always assume __builtin_constant_p(...) ? ... : ... is a potential 2449 // constant expression; we can't check whether it's potentially foldable. 2450 if (Info.CheckingPotentialConstantExpression && IsBcpCall) 2451 return false; 2452 2453 FoldConstant Fold(Info); 2454 2455 if (!HandleConditionalOperator(E)) 2456 return false; 2457 2458 if (IsBcpCall) 2459 Fold.Fold(Info); 2460 2461 return true; 2462 } 2463 2464 RetTy VisitOpaqueValueExpr(const OpaqueValueExpr *E) { 2465 APValue &Value = Info.CurrentCall->Temporaries[E]; 2466 if (Value.isUninit()) { 2467 const Expr *Source = E->getSourceExpr(); 2468 if (!Source) 2469 return Error(E); 2470 if (Source == E) { // sanity checking. 2471 assert(0 && "OpaqueValueExpr recursively refers to itself"); 2472 return Error(E); 2473 } 2474 return StmtVisitorTy::Visit(Source); 2475 } 2476 return DerivedSuccess(Value, E); 2477 } 2478 2479 RetTy VisitCallExpr(const CallExpr *E) { 2480 const Expr *Callee = E->getCallee()->IgnoreParens(); 2481 QualType CalleeType = Callee->getType(); 2482 2483 const FunctionDecl *FD = 0; 2484 LValue *This = 0, ThisVal; 2485 llvm::ArrayRef<const Expr*> Args(E->getArgs(), E->getNumArgs()); 2486 bool HasQualifier = false; 2487 2488 // Extract function decl and 'this' pointer from the callee. 2489 if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) { 2490 const ValueDecl *Member = 0; 2491 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) { 2492 // Explicit bound member calls, such as x.f() or p->g(); 2493 if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal)) 2494 return false; 2495 Member = ME->getMemberDecl(); 2496 This = &ThisVal; 2497 HasQualifier = ME->hasQualifier(); 2498 } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) { 2499 // Indirect bound member calls ('.*' or '->*'). 2500 Member = HandleMemberPointerAccess(Info, BE, ThisVal, false); 2501 if (!Member) return false; 2502 This = &ThisVal; 2503 } else 2504 return Error(Callee); 2505 2506 FD = dyn_cast<FunctionDecl>(Member); 2507 if (!FD) 2508 return Error(Callee); 2509 } else if (CalleeType->isFunctionPointerType()) { 2510 LValue Call; 2511 if (!EvaluatePointer(Callee, Call, Info)) 2512 return false; 2513 2514 if (!Call.getLValueOffset().isZero()) 2515 return Error(Callee); 2516 FD = dyn_cast_or_null<FunctionDecl>( 2517 Call.getLValueBase().dyn_cast<const ValueDecl*>()); 2518 if (!FD) 2519 return Error(Callee); 2520 2521 // Overloaded operator calls to member functions are represented as normal 2522 // calls with '*this' as the first argument. 2523 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); 2524 if (MD && !MD->isStatic()) { 2525 // FIXME: When selecting an implicit conversion for an overloaded 2526 // operator delete, we sometimes try to evaluate calls to conversion 2527 // operators without a 'this' parameter! 2528 if (Args.empty()) 2529 return Error(E); 2530 2531 if (!EvaluateObjectArgument(Info, Args[0], ThisVal)) 2532 return false; 2533 This = &ThisVal; 2534 Args = Args.slice(1); 2535 } 2536 2537 // Don't call function pointers which have been cast to some other type. 2538 if (!Info.Ctx.hasSameType(CalleeType->getPointeeType(), FD->getType())) 2539 return Error(E); 2540 } else 2541 return Error(E); 2542 2543 if (This && !This->checkSubobject(Info, E, CSK_This)) 2544 return false; 2545 2546 // DR1358 allows virtual constexpr functions in some cases. Don't allow 2547 // calls to such functions in constant expressions. 2548 if (This && !HasQualifier && 2549 isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isVirtual()) 2550 return Error(E, diag::note_constexpr_virtual_call); 2551 2552 const FunctionDecl *Definition = 0; 2553 Stmt *Body = FD->getBody(Definition); 2554 APValue Result; 2555 2556 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition) || 2557 !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, 2558 Info, Result)) 2559 return false; 2560 2561 return DerivedSuccess(Result, E); 2562 } 2563 2564 RetTy VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { 2565 return StmtVisitorTy::Visit(E->getInitializer()); 2566 } 2567 RetTy VisitInitListExpr(const InitListExpr *E) { 2568 if (E->getNumInits() == 0) 2569 return DerivedZeroInitialization(E); 2570 if (E->getNumInits() == 1) 2571 return StmtVisitorTy::Visit(E->getInit(0)); 2572 return Error(E); 2573 } 2574 RetTy VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) { 2575 return DerivedZeroInitialization(E); 2576 } 2577 RetTy VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) { 2578 return DerivedZeroInitialization(E); 2579 } 2580 RetTy VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) { 2581 return DerivedZeroInitialization(E); 2582 } 2583 2584 /// A member expression where the object is a prvalue is itself a prvalue. 2585 RetTy VisitMemberExpr(const MemberExpr *E) { 2586 assert(!E->isArrow() && "missing call to bound member function?"); 2587 2588 APValue Val; 2589 if (!Evaluate(Val, Info, E->getBase())) 2590 return false; 2591 2592 QualType BaseTy = E->getBase()->getType(); 2593 2594 const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl()); 2595 if (!FD) return Error(E); 2596 assert(!FD->getType()->isReferenceType() && "prvalue reference?"); 2597 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == 2598 FD->getParent()->getCanonicalDecl() && "record / field mismatch"); 2599 2600 SubobjectDesignator Designator(BaseTy); 2601 Designator.addDeclUnchecked(FD); 2602 2603 return ExtractSubobject(Info, E, Val, BaseTy, Designator, E->getType()) && 2604 DerivedSuccess(Val, E); 2605 } 2606 2607 RetTy VisitCastExpr(const CastExpr *E) { 2608 switch (E->getCastKind()) { 2609 default: 2610 break; 2611 2612 case CK_AtomicToNonAtomic: 2613 case CK_NonAtomicToAtomic: 2614 case CK_NoOp: 2615 case CK_UserDefinedConversion: 2616 return StmtVisitorTy::Visit(E->getSubExpr()); 2617 2618 case CK_LValueToRValue: { 2619 LValue LVal; 2620 if (!EvaluateLValue(E->getSubExpr(), LVal, Info)) 2621 return false; 2622 APValue RVal; 2623 // Note, we use the subexpression's type in order to retain cv-qualifiers. 2624 if (!HandleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(), 2625 LVal, RVal)) 2626 return false; 2627 return DerivedSuccess(RVal, E); 2628 } 2629 } 2630 2631 return Error(E); 2632 } 2633 2634 /// Visit a value which is evaluated, but whose value is ignored. 2635 void VisitIgnoredValue(const Expr *E) { 2636 APValue Scratch; 2637 if (!Evaluate(Scratch, Info, E)) 2638 Info.EvalStatus.HasSideEffects = true; 2639 } 2640 }; 2641 2642 } 2643 2644 //===----------------------------------------------------------------------===// 2645 // Common base class for lvalue and temporary evaluation. 2646 //===----------------------------------------------------------------------===// 2647 namespace { 2648 template<class Derived> 2649 class LValueExprEvaluatorBase 2650 : public ExprEvaluatorBase<Derived, bool> { 2651 protected: 2652 LValue &Result; 2653 typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy; 2654 typedef ExprEvaluatorBase<Derived, bool> ExprEvaluatorBaseTy; 2655 2656 bool Success(APValue::LValueBase B) { 2657 Result.set(B); 2658 return true; 2659 } 2660 2661 public: 2662 LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result) : 2663 ExprEvaluatorBaseTy(Info), Result(Result) {} 2664 2665 bool Success(const APValue &V, const Expr *E) { 2666 Result.setFrom(this->Info.Ctx, V); 2667 return true; 2668 } 2669 2670 bool VisitMemberExpr(const MemberExpr *E) { 2671 // Handle non-static data members. 2672 QualType BaseTy; 2673 if (E->isArrow()) { 2674 if (!EvaluatePointer(E->getBase(), Result, this->Info)) 2675 return false; 2676 BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType(); 2677 } else if (E->getBase()->isRValue()) { 2678 assert(E->getBase()->getType()->isRecordType()); 2679 if (!EvaluateTemporary(E->getBase(), Result, this->Info)) 2680 return false; 2681 BaseTy = E->getBase()->getType(); 2682 } else { 2683 if (!this->Visit(E->getBase())) 2684 return false; 2685 BaseTy = E->getBase()->getType(); 2686 } 2687 2688 const ValueDecl *MD = E->getMemberDecl(); 2689 if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) { 2690 assert(BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() == 2691 FD->getParent()->getCanonicalDecl() && "record / field mismatch"); 2692 (void)BaseTy; 2693 if (!HandleLValueMember(this->Info, E, Result, FD)) 2694 return false; 2695 } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) { 2696 if (!HandleLValueIndirectMember(this->Info, E, Result, IFD)) 2697 return false; 2698 } else 2699 return this->Error(E); 2700 2701 if (MD->getType()->isReferenceType()) { 2702 APValue RefValue; 2703 if (!HandleLValueToRValueConversion(this->Info, E, MD->getType(), Result, 2704 RefValue)) 2705 return false; 2706 return Success(RefValue, E); 2707 } 2708 return true; 2709 } 2710 2711 bool VisitBinaryOperator(const BinaryOperator *E) { 2712 switch (E->getOpcode()) { 2713 default: 2714 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 2715 2716 case BO_PtrMemD: 2717 case BO_PtrMemI: 2718 return HandleMemberPointerAccess(this->Info, E, Result); 2719 } 2720 } 2721 2722 bool VisitCastExpr(const CastExpr *E) { 2723 switch (E->getCastKind()) { 2724 default: 2725 return ExprEvaluatorBaseTy::VisitCastExpr(E); 2726 2727 case CK_DerivedToBase: 2728 case CK_UncheckedDerivedToBase: { 2729 if (!this->Visit(E->getSubExpr())) 2730 return false; 2731 2732 // Now figure out the necessary offset to add to the base LV to get from 2733 // the derived class to the base class. 2734 QualType Type = E->getSubExpr()->getType(); 2735 2736 for (CastExpr::path_const_iterator PathI = E->path_begin(), 2737 PathE = E->path_end(); PathI != PathE; ++PathI) { 2738 if (!HandleLValueBase(this->Info, E, Result, Type->getAsCXXRecordDecl(), 2739 *PathI)) 2740 return false; 2741 Type = (*PathI)->getType(); 2742 } 2743 2744 return true; 2745 } 2746 } 2747 } 2748 }; 2749 } 2750 2751 //===----------------------------------------------------------------------===// 2752 // LValue Evaluation 2753 // 2754 // This is used for evaluating lvalues (in C and C++), xvalues (in C++11), 2755 // function designators (in C), decl references to void objects (in C), and 2756 // temporaries (if building with -Wno-address-of-temporary). 2757 // 2758 // LValue evaluation produces values comprising a base expression of one of the 2759 // following types: 2760 // - Declarations 2761 // * VarDecl 2762 // * FunctionDecl 2763 // - Literals 2764 // * CompoundLiteralExpr in C 2765 // * StringLiteral 2766 // * CXXTypeidExpr 2767 // * PredefinedExpr 2768 // * ObjCStringLiteralExpr 2769 // * ObjCEncodeExpr 2770 // * AddrLabelExpr 2771 // * BlockExpr 2772 // * CallExpr for a MakeStringConstant builtin 2773 // - Locals and temporaries 2774 // * Any Expr, with a CallIndex indicating the function in which the temporary 2775 // was evaluated. 2776 // plus an offset in bytes. 2777 //===----------------------------------------------------------------------===// 2778 namespace { 2779 class LValueExprEvaluator 2780 : public LValueExprEvaluatorBase<LValueExprEvaluator> { 2781 public: 2782 LValueExprEvaluator(EvalInfo &Info, LValue &Result) : 2783 LValueExprEvaluatorBaseTy(Info, Result) {} 2784 2785 bool VisitVarDecl(const Expr *E, const VarDecl *VD); 2786 2787 bool VisitDeclRefExpr(const DeclRefExpr *E); 2788 bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); } 2789 bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E); 2790 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E); 2791 bool VisitMemberExpr(const MemberExpr *E); 2792 bool VisitStringLiteral(const StringLiteral *E) { return Success(E); } 2793 bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); } 2794 bool VisitCXXTypeidExpr(const CXXTypeidExpr *E); 2795 bool VisitCXXUuidofExpr(const CXXUuidofExpr *E); 2796 bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E); 2797 bool VisitUnaryDeref(const UnaryOperator *E); 2798 bool VisitUnaryReal(const UnaryOperator *E); 2799 bool VisitUnaryImag(const UnaryOperator *E); 2800 2801 bool VisitCastExpr(const CastExpr *E) { 2802 switch (E->getCastKind()) { 2803 default: 2804 return LValueExprEvaluatorBaseTy::VisitCastExpr(E); 2805 2806 case CK_LValueBitCast: 2807 this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 2808 if (!Visit(E->getSubExpr())) 2809 return false; 2810 Result.Designator.setInvalid(); 2811 return true; 2812 2813 case CK_BaseToDerived: 2814 if (!Visit(E->getSubExpr())) 2815 return false; 2816 return HandleBaseToDerivedCast(Info, E, Result); 2817 } 2818 } 2819 }; 2820 } // end anonymous namespace 2821 2822 /// Evaluate an expression as an lvalue. This can be legitimately called on 2823 /// expressions which are not glvalues, in a few cases: 2824 /// * function designators in C, 2825 /// * "extern void" objects, 2826 /// * temporaries, if building with -Wno-address-of-temporary. 2827 static bool EvaluateLValue(const Expr* E, LValue& Result, EvalInfo &Info) { 2828 assert((E->isGLValue() || E->getType()->isFunctionType() || 2829 E->getType()->isVoidType() || isa<CXXTemporaryObjectExpr>(E)) && 2830 "can't evaluate expression as an lvalue"); 2831 return LValueExprEvaluator(Info, Result).Visit(E); 2832 } 2833 2834 bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) { 2835 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl())) 2836 return Success(FD); 2837 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl())) 2838 return VisitVarDecl(E, VD); 2839 return Error(E); 2840 } 2841 2842 bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) { 2843 if (!VD->getType()->isReferenceType()) { 2844 if (isa<ParmVarDecl>(VD)) { 2845 Result.set(VD, Info.CurrentCall->Index); 2846 return true; 2847 } 2848 return Success(VD); 2849 } 2850 2851 APValue V; 2852 if (!EvaluateVarDeclInit(Info, E, VD, Info.CurrentCall, V)) 2853 return false; 2854 return Success(V, E); 2855 } 2856 2857 bool LValueExprEvaluator::VisitMaterializeTemporaryExpr( 2858 const MaterializeTemporaryExpr *E) { 2859 if (E->GetTemporaryExpr()->isRValue()) { 2860 if (E->getType()->isRecordType()) 2861 return EvaluateTemporary(E->GetTemporaryExpr(), Result, Info); 2862 2863 Result.set(E, Info.CurrentCall->Index); 2864 return EvaluateInPlace(Info.CurrentCall->Temporaries[E], Info, 2865 Result, E->GetTemporaryExpr()); 2866 } 2867 2868 // Materialization of an lvalue temporary occurs when we need to force a copy 2869 // (for instance, if it's a bitfield). 2870 // FIXME: The AST should contain an lvalue-to-rvalue node for such cases. 2871 if (!Visit(E->GetTemporaryExpr())) 2872 return false; 2873 if (!HandleLValueToRValueConversion(Info, E, E->getType(), Result, 2874 Info.CurrentCall->Temporaries[E])) 2875 return false; 2876 Result.set(E, Info.CurrentCall->Index); 2877 return true; 2878 } 2879 2880 bool 2881 LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { 2882 assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?"); 2883 // Defer visiting the literal until the lvalue-to-rvalue conversion. We can 2884 // only see this when folding in C, so there's no standard to follow here. 2885 return Success(E); 2886 } 2887 2888 bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) { 2889 if (E->isTypeOperand()) 2890 return Success(E); 2891 CXXRecordDecl *RD = E->getExprOperand()->getType()->getAsCXXRecordDecl(); 2892 // FIXME: The standard says "a typeid expression whose operand is of a 2893 // polymorphic class type" is not a constant expression, but it probably 2894 // means "a typeid expression whose operand is potentially evaluated". 2895 if (RD && RD->isPolymorphic()) { 2896 Info.Diag(E, diag::note_constexpr_typeid_polymorphic) 2897 << E->getExprOperand()->getType() 2898 << E->getExprOperand()->getSourceRange(); 2899 return false; 2900 } 2901 return Success(E); 2902 } 2903 2904 bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) { 2905 return Success(E); 2906 } 2907 2908 bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) { 2909 // Handle static data members. 2910 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) { 2911 VisitIgnoredValue(E->getBase()); 2912 return VisitVarDecl(E, VD); 2913 } 2914 2915 // Handle static member functions. 2916 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) { 2917 if (MD->isStatic()) { 2918 VisitIgnoredValue(E->getBase()); 2919 return Success(MD); 2920 } 2921 } 2922 2923 // Handle non-static data members. 2924 return LValueExprEvaluatorBaseTy::VisitMemberExpr(E); 2925 } 2926 2927 bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) { 2928 // FIXME: Deal with vectors as array subscript bases. 2929 if (E->getBase()->getType()->isVectorType()) 2930 return Error(E); 2931 2932 if (!EvaluatePointer(E->getBase(), Result, Info)) 2933 return false; 2934 2935 APSInt Index; 2936 if (!EvaluateInteger(E->getIdx(), Index, Info)) 2937 return false; 2938 int64_t IndexValue 2939 = Index.isSigned() ? Index.getSExtValue() 2940 : static_cast<int64_t>(Index.getZExtValue()); 2941 2942 return HandleLValueArrayAdjustment(Info, E, Result, E->getType(), IndexValue); 2943 } 2944 2945 bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) { 2946 return EvaluatePointer(E->getSubExpr(), Result, Info); 2947 } 2948 2949 bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 2950 if (!Visit(E->getSubExpr())) 2951 return false; 2952 // __real is a no-op on scalar lvalues. 2953 if (E->getSubExpr()->getType()->isAnyComplexType()) 2954 HandleLValueComplexElement(Info, E, Result, E->getType(), false); 2955 return true; 2956 } 2957 2958 bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 2959 assert(E->getSubExpr()->getType()->isAnyComplexType() && 2960 "lvalue __imag__ on scalar?"); 2961 if (!Visit(E->getSubExpr())) 2962 return false; 2963 HandleLValueComplexElement(Info, E, Result, E->getType(), true); 2964 return true; 2965 } 2966 2967 //===----------------------------------------------------------------------===// 2968 // Pointer Evaluation 2969 //===----------------------------------------------------------------------===// 2970 2971 namespace { 2972 class PointerExprEvaluator 2973 : public ExprEvaluatorBase<PointerExprEvaluator, bool> { 2974 LValue &Result; 2975 2976 bool Success(const Expr *E) { 2977 Result.set(E); 2978 return true; 2979 } 2980 public: 2981 2982 PointerExprEvaluator(EvalInfo &info, LValue &Result) 2983 : ExprEvaluatorBaseTy(info), Result(Result) {} 2984 2985 bool Success(const APValue &V, const Expr *E) { 2986 Result.setFrom(Info.Ctx, V); 2987 return true; 2988 } 2989 bool ZeroInitialization(const Expr *E) { 2990 return Success((Expr*)0); 2991 } 2992 2993 bool VisitBinaryOperator(const BinaryOperator *E); 2994 bool VisitCastExpr(const CastExpr* E); 2995 bool VisitUnaryAddrOf(const UnaryOperator *E); 2996 bool VisitObjCStringLiteral(const ObjCStringLiteral *E) 2997 { return Success(E); } 2998 bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) 2999 { return Success(E); } 3000 bool VisitAddrLabelExpr(const AddrLabelExpr *E) 3001 { return Success(E); } 3002 bool VisitCallExpr(const CallExpr *E); 3003 bool VisitBlockExpr(const BlockExpr *E) { 3004 if (!E->getBlockDecl()->hasCaptures()) 3005 return Success(E); 3006 return Error(E); 3007 } 3008 bool VisitCXXThisExpr(const CXXThisExpr *E) { 3009 if (!Info.CurrentCall->This) 3010 return Error(E); 3011 Result = *Info.CurrentCall->This; 3012 return true; 3013 } 3014 3015 // FIXME: Missing: @protocol, @selector 3016 }; 3017 } // end anonymous namespace 3018 3019 static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info) { 3020 assert(E->isRValue() && E->getType()->hasPointerRepresentation()); 3021 return PointerExprEvaluator(Info, Result).Visit(E); 3022 } 3023 3024 bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 3025 if (E->getOpcode() != BO_Add && 3026 E->getOpcode() != BO_Sub) 3027 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 3028 3029 const Expr *PExp = E->getLHS(); 3030 const Expr *IExp = E->getRHS(); 3031 if (IExp->getType()->isPointerType()) 3032 std::swap(PExp, IExp); 3033 3034 bool EvalPtrOK = EvaluatePointer(PExp, Result, Info); 3035 if (!EvalPtrOK && !Info.keepEvaluatingAfterFailure()) 3036 return false; 3037 3038 llvm::APSInt Offset; 3039 if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK) 3040 return false; 3041 int64_t AdditionalOffset 3042 = Offset.isSigned() ? Offset.getSExtValue() 3043 : static_cast<int64_t>(Offset.getZExtValue()); 3044 if (E->getOpcode() == BO_Sub) 3045 AdditionalOffset = -AdditionalOffset; 3046 3047 QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType(); 3048 return HandleLValueArrayAdjustment(Info, E, Result, Pointee, 3049 AdditionalOffset); 3050 } 3051 3052 bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { 3053 return EvaluateLValue(E->getSubExpr(), Result, Info); 3054 } 3055 3056 bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) { 3057 const Expr* SubExpr = E->getSubExpr(); 3058 3059 switch (E->getCastKind()) { 3060 default: 3061 break; 3062 3063 case CK_BitCast: 3064 case CK_CPointerToObjCPointerCast: 3065 case CK_BlockPointerToObjCPointerCast: 3066 case CK_AnyPointerToBlockPointerCast: 3067 if (!Visit(SubExpr)) 3068 return false; 3069 // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are 3070 // permitted in constant expressions in C++11. Bitcasts from cv void* are 3071 // also static_casts, but we disallow them as a resolution to DR1312. 3072 if (!E->getType()->isVoidPointerType()) { 3073 Result.Designator.setInvalid(); 3074 if (SubExpr->getType()->isVoidPointerType()) 3075 CCEDiag(E, diag::note_constexpr_invalid_cast) 3076 << 3 << SubExpr->getType(); 3077 else 3078 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 3079 } 3080 return true; 3081 3082 case CK_DerivedToBase: 3083 case CK_UncheckedDerivedToBase: { 3084 if (!EvaluatePointer(E->getSubExpr(), Result, Info)) 3085 return false; 3086 if (!Result.Base && Result.Offset.isZero()) 3087 return true; 3088 3089 // Now figure out the necessary offset to add to the base LV to get from 3090 // the derived class to the base class. 3091 QualType Type = 3092 E->getSubExpr()->getType()->castAs<PointerType>()->getPointeeType(); 3093 3094 for (CastExpr::path_const_iterator PathI = E->path_begin(), 3095 PathE = E->path_end(); PathI != PathE; ++PathI) { 3096 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(), 3097 *PathI)) 3098 return false; 3099 Type = (*PathI)->getType(); 3100 } 3101 3102 return true; 3103 } 3104 3105 case CK_BaseToDerived: 3106 if (!Visit(E->getSubExpr())) 3107 return false; 3108 if (!Result.Base && Result.Offset.isZero()) 3109 return true; 3110 return HandleBaseToDerivedCast(Info, E, Result); 3111 3112 case CK_NullToPointer: 3113 VisitIgnoredValue(E->getSubExpr()); 3114 return ZeroInitialization(E); 3115 3116 case CK_IntegralToPointer: { 3117 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 3118 3119 APValue Value; 3120 if (!EvaluateIntegerOrLValue(SubExpr, Value, Info)) 3121 break; 3122 3123 if (Value.isInt()) { 3124 unsigned Size = Info.Ctx.getTypeSize(E->getType()); 3125 uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue(); 3126 Result.Base = (Expr*)0; 3127 Result.Offset = CharUnits::fromQuantity(N); 3128 Result.CallIndex = 0; 3129 Result.Designator.setInvalid(); 3130 return true; 3131 } else { 3132 // Cast is of an lvalue, no need to change value. 3133 Result.setFrom(Info.Ctx, Value); 3134 return true; 3135 } 3136 } 3137 case CK_ArrayToPointerDecay: 3138 if (SubExpr->isGLValue()) { 3139 if (!EvaluateLValue(SubExpr, Result, Info)) 3140 return false; 3141 } else { 3142 Result.set(SubExpr, Info.CurrentCall->Index); 3143 if (!EvaluateInPlace(Info.CurrentCall->Temporaries[SubExpr], 3144 Info, Result, SubExpr)) 3145 return false; 3146 } 3147 // The result is a pointer to the first element of the array. 3148 if (const ConstantArrayType *CAT 3149 = Info.Ctx.getAsConstantArrayType(SubExpr->getType())) 3150 Result.addArray(Info, E, CAT); 3151 else 3152 Result.Designator.setInvalid(); 3153 return true; 3154 3155 case CK_FunctionToPointerDecay: 3156 return EvaluateLValue(SubExpr, Result, Info); 3157 } 3158 3159 return ExprEvaluatorBaseTy::VisitCastExpr(E); 3160 } 3161 3162 bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) { 3163 if (IsStringLiteralCall(E)) 3164 return Success(E); 3165 3166 return ExprEvaluatorBaseTy::VisitCallExpr(E); 3167 } 3168 3169 //===----------------------------------------------------------------------===// 3170 // Member Pointer Evaluation 3171 //===----------------------------------------------------------------------===// 3172 3173 namespace { 3174 class MemberPointerExprEvaluator 3175 : public ExprEvaluatorBase<MemberPointerExprEvaluator, bool> { 3176 MemberPtr &Result; 3177 3178 bool Success(const ValueDecl *D) { 3179 Result = MemberPtr(D); 3180 return true; 3181 } 3182 public: 3183 3184 MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result) 3185 : ExprEvaluatorBaseTy(Info), Result(Result) {} 3186 3187 bool Success(const APValue &V, const Expr *E) { 3188 Result.setFrom(V); 3189 return true; 3190 } 3191 bool ZeroInitialization(const Expr *E) { 3192 return Success((const ValueDecl*)0); 3193 } 3194 3195 bool VisitCastExpr(const CastExpr *E); 3196 bool VisitUnaryAddrOf(const UnaryOperator *E); 3197 }; 3198 } // end anonymous namespace 3199 3200 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, 3201 EvalInfo &Info) { 3202 assert(E->isRValue() && E->getType()->isMemberPointerType()); 3203 return MemberPointerExprEvaluator(Info, Result).Visit(E); 3204 } 3205 3206 bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) { 3207 switch (E->getCastKind()) { 3208 default: 3209 return ExprEvaluatorBaseTy::VisitCastExpr(E); 3210 3211 case CK_NullToMemberPointer: 3212 VisitIgnoredValue(E->getSubExpr()); 3213 return ZeroInitialization(E); 3214 3215 case CK_BaseToDerivedMemberPointer: { 3216 if (!Visit(E->getSubExpr())) 3217 return false; 3218 if (E->path_empty()) 3219 return true; 3220 // Base-to-derived member pointer casts store the path in derived-to-base 3221 // order, so iterate backwards. The CXXBaseSpecifier also provides us with 3222 // the wrong end of the derived->base arc, so stagger the path by one class. 3223 typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter; 3224 for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin()); 3225 PathI != PathE; ++PathI) { 3226 assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); 3227 const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl(); 3228 if (!Result.castToDerived(Derived)) 3229 return Error(E); 3230 } 3231 const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass(); 3232 if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl())) 3233 return Error(E); 3234 return true; 3235 } 3236 3237 case CK_DerivedToBaseMemberPointer: 3238 if (!Visit(E->getSubExpr())) 3239 return false; 3240 for (CastExpr::path_const_iterator PathI = E->path_begin(), 3241 PathE = E->path_end(); PathI != PathE; ++PathI) { 3242 assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); 3243 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); 3244 if (!Result.castToBase(Base)) 3245 return Error(E); 3246 } 3247 return true; 3248 } 3249 } 3250 3251 bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { 3252 // C++11 [expr.unary.op]p3 has very strict rules on how the address of a 3253 // member can be formed. 3254 return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl()); 3255 } 3256 3257 //===----------------------------------------------------------------------===// 3258 // Record Evaluation 3259 //===----------------------------------------------------------------------===// 3260 3261 namespace { 3262 class RecordExprEvaluator 3263 : public ExprEvaluatorBase<RecordExprEvaluator, bool> { 3264 const LValue &This; 3265 APValue &Result; 3266 public: 3267 3268 RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result) 3269 : ExprEvaluatorBaseTy(info), This(This), Result(Result) {} 3270 3271 bool Success(const APValue &V, const Expr *E) { 3272 Result = V; 3273 return true; 3274 } 3275 bool ZeroInitialization(const Expr *E); 3276 3277 bool VisitCastExpr(const CastExpr *E); 3278 bool VisitInitListExpr(const InitListExpr *E); 3279 bool VisitCXXConstructExpr(const CXXConstructExpr *E); 3280 }; 3281 } 3282 3283 /// Perform zero-initialization on an object of non-union class type. 3284 /// C++11 [dcl.init]p5: 3285 /// To zero-initialize an object or reference of type T means: 3286 /// [...] 3287 /// -- if T is a (possibly cv-qualified) non-union class type, 3288 /// each non-static data member and each base-class subobject is 3289 /// zero-initialized 3290 static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E, 3291 const RecordDecl *RD, 3292 const LValue &This, APValue &Result) { 3293 assert(!RD->isUnion() && "Expected non-union class type"); 3294 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD); 3295 Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0, 3296 std::distance(RD->field_begin(), RD->field_end())); 3297 3298 if (RD->isInvalidDecl()) return false; 3299 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 3300 3301 if (CD) { 3302 unsigned Index = 0; 3303 for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), 3304 End = CD->bases_end(); I != End; ++I, ++Index) { 3305 const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl(); 3306 LValue Subobject = This; 3307 if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout)) 3308 return false; 3309 if (!HandleClassZeroInitialization(Info, E, Base, Subobject, 3310 Result.getStructBase(Index))) 3311 return false; 3312 } 3313 } 3314 3315 for (RecordDecl::field_iterator I = RD->field_begin(), End = RD->field_end(); 3316 I != End; ++I) { 3317 // -- if T is a reference type, no initialization is performed. 3318 if (I->getType()->isReferenceType()) 3319 continue; 3320 3321 LValue Subobject = This; 3322 if (!HandleLValueMember(Info, E, Subobject, *I, &Layout)) 3323 return false; 3324 3325 ImplicitValueInitExpr VIE(I->getType()); 3326 if (!EvaluateInPlace( 3327 Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE)) 3328 return false; 3329 } 3330 3331 return true; 3332 } 3333 3334 bool RecordExprEvaluator::ZeroInitialization(const Expr *E) { 3335 const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl(); 3336 if (RD->isInvalidDecl()) return false; 3337 if (RD->isUnion()) { 3338 // C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the 3339 // object's first non-static named data member is zero-initialized 3340 RecordDecl::field_iterator I = RD->field_begin(); 3341 if (I == RD->field_end()) { 3342 Result = APValue((const FieldDecl*)0); 3343 return true; 3344 } 3345 3346 LValue Subobject = This; 3347 if (!HandleLValueMember(Info, E, Subobject, *I)) 3348 return false; 3349 Result = APValue(*I); 3350 ImplicitValueInitExpr VIE(I->getType()); 3351 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE); 3352 } 3353 3354 if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) { 3355 Info.Diag(E, diag::note_constexpr_virtual_base) << RD; 3356 return false; 3357 } 3358 3359 return HandleClassZeroInitialization(Info, E, RD, This, Result); 3360 } 3361 3362 bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) { 3363 switch (E->getCastKind()) { 3364 default: 3365 return ExprEvaluatorBaseTy::VisitCastExpr(E); 3366 3367 case CK_ConstructorConversion: 3368 return Visit(E->getSubExpr()); 3369 3370 case CK_DerivedToBase: 3371 case CK_UncheckedDerivedToBase: { 3372 APValue DerivedObject; 3373 if (!Evaluate(DerivedObject, Info, E->getSubExpr())) 3374 return false; 3375 if (!DerivedObject.isStruct()) 3376 return Error(E->getSubExpr()); 3377 3378 // Derived-to-base rvalue conversion: just slice off the derived part. 3379 APValue *Value = &DerivedObject; 3380 const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl(); 3381 for (CastExpr::path_const_iterator PathI = E->path_begin(), 3382 PathE = E->path_end(); PathI != PathE; ++PathI) { 3383 assert(!(*PathI)->isVirtual() && "record rvalue with virtual base"); 3384 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); 3385 Value = &Value->getStructBase(getBaseIndex(RD, Base)); 3386 RD = Base; 3387 } 3388 Result = *Value; 3389 return true; 3390 } 3391 } 3392 } 3393 3394 bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 3395 // Cannot constant-evaluate std::initializer_list inits. 3396 if (E->initializesStdInitializerList()) 3397 return false; 3398 3399 const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl(); 3400 if (RD->isInvalidDecl()) return false; 3401 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 3402 3403 if (RD->isUnion()) { 3404 const FieldDecl *Field = E->getInitializedFieldInUnion(); 3405 Result = APValue(Field); 3406 if (!Field) 3407 return true; 3408 3409 // If the initializer list for a union does not contain any elements, the 3410 // first element of the union is value-initialized. 3411 ImplicitValueInitExpr VIE(Field->getType()); 3412 const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE; 3413 3414 LValue Subobject = This; 3415 if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout)) 3416 return false; 3417 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr); 3418 } 3419 3420 assert((!isa<CXXRecordDecl>(RD) || !cast<CXXRecordDecl>(RD)->getNumBases()) && 3421 "initializer list for class with base classes"); 3422 Result = APValue(APValue::UninitStruct(), 0, 3423 std::distance(RD->field_begin(), RD->field_end())); 3424 unsigned ElementNo = 0; 3425 bool Success = true; 3426 for (RecordDecl::field_iterator Field = RD->field_begin(), 3427 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field) { 3428 // Anonymous bit-fields are not considered members of the class for 3429 // purposes of aggregate initialization. 3430 if (Field->isUnnamedBitfield()) 3431 continue; 3432 3433 LValue Subobject = This; 3434 3435 bool HaveInit = ElementNo < E->getNumInits(); 3436 3437 // FIXME: Diagnostics here should point to the end of the initializer 3438 // list, not the start. 3439 if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E, 3440 Subobject, *Field, &Layout)) 3441 return false; 3442 3443 // Perform an implicit value-initialization for members beyond the end of 3444 // the initializer list. 3445 ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType()); 3446 3447 if (!EvaluateInPlace( 3448 Result.getStructField(Field->getFieldIndex()), 3449 Info, Subobject, HaveInit ? E->getInit(ElementNo++) : &VIE)) { 3450 if (!Info.keepEvaluatingAfterFailure()) 3451 return false; 3452 Success = false; 3453 } 3454 } 3455 3456 return Success; 3457 } 3458 3459 bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { 3460 const CXXConstructorDecl *FD = E->getConstructor(); 3461 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false; 3462 3463 bool ZeroInit = E->requiresZeroInitialization(); 3464 if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { 3465 // If we've already performed zero-initialization, we're already done. 3466 if (!Result.isUninit()) 3467 return true; 3468 3469 if (ZeroInit) 3470 return ZeroInitialization(E); 3471 3472 const CXXRecordDecl *RD = FD->getParent(); 3473 if (RD->isUnion()) 3474 Result = APValue((FieldDecl*)0); 3475 else 3476 Result = APValue(APValue::UninitStruct(), RD->getNumBases(), 3477 std::distance(RD->field_begin(), RD->field_end())); 3478 return true; 3479 } 3480 3481 const FunctionDecl *Definition = 0; 3482 FD->getBody(Definition); 3483 3484 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition)) 3485 return false; 3486 3487 // Avoid materializing a temporary for an elidable copy/move constructor. 3488 if (E->isElidable() && !ZeroInit) 3489 if (const MaterializeTemporaryExpr *ME 3490 = dyn_cast<MaterializeTemporaryExpr>(E->getArg(0))) 3491 return Visit(ME->GetTemporaryExpr()); 3492 3493 if (ZeroInit && !ZeroInitialization(E)) 3494 return false; 3495 3496 llvm::ArrayRef<const Expr*> Args(E->getArgs(), E->getNumArgs()); 3497 return HandleConstructorCall(E->getExprLoc(), This, Args, 3498 cast<CXXConstructorDecl>(Definition), Info, 3499 Result); 3500 } 3501 3502 static bool EvaluateRecord(const Expr *E, const LValue &This, 3503 APValue &Result, EvalInfo &Info) { 3504 assert(E->isRValue() && E->getType()->isRecordType() && 3505 "can't evaluate expression as a record rvalue"); 3506 return RecordExprEvaluator(Info, This, Result).Visit(E); 3507 } 3508 3509 //===----------------------------------------------------------------------===// 3510 // Temporary Evaluation 3511 // 3512 // Temporaries are represented in the AST as rvalues, but generally behave like 3513 // lvalues. The full-object of which the temporary is a subobject is implicitly 3514 // materialized so that a reference can bind to it. 3515 //===----------------------------------------------------------------------===// 3516 namespace { 3517 class TemporaryExprEvaluator 3518 : public LValueExprEvaluatorBase<TemporaryExprEvaluator> { 3519 public: 3520 TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) : 3521 LValueExprEvaluatorBaseTy(Info, Result) {} 3522 3523 /// Visit an expression which constructs the value of this temporary. 3524 bool VisitConstructExpr(const Expr *E) { 3525 Result.set(E, Info.CurrentCall->Index); 3526 return EvaluateInPlace(Info.CurrentCall->Temporaries[E], Info, Result, E); 3527 } 3528 3529 bool VisitCastExpr(const CastExpr *E) { 3530 switch (E->getCastKind()) { 3531 default: 3532 return LValueExprEvaluatorBaseTy::VisitCastExpr(E); 3533 3534 case CK_ConstructorConversion: 3535 return VisitConstructExpr(E->getSubExpr()); 3536 } 3537 } 3538 bool VisitInitListExpr(const InitListExpr *E) { 3539 return VisitConstructExpr(E); 3540 } 3541 bool VisitCXXConstructExpr(const CXXConstructExpr *E) { 3542 return VisitConstructExpr(E); 3543 } 3544 bool VisitCallExpr(const CallExpr *E) { 3545 return VisitConstructExpr(E); 3546 } 3547 }; 3548 } // end anonymous namespace 3549 3550 /// Evaluate an expression of record type as a temporary. 3551 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) { 3552 assert(E->isRValue() && E->getType()->isRecordType()); 3553 return TemporaryExprEvaluator(Info, Result).Visit(E); 3554 } 3555 3556 //===----------------------------------------------------------------------===// 3557 // Vector Evaluation 3558 //===----------------------------------------------------------------------===// 3559 3560 namespace { 3561 class VectorExprEvaluator 3562 : public ExprEvaluatorBase<VectorExprEvaluator, bool> { 3563 APValue &Result; 3564 public: 3565 3566 VectorExprEvaluator(EvalInfo &info, APValue &Result) 3567 : ExprEvaluatorBaseTy(info), Result(Result) {} 3568 3569 bool Success(const ArrayRef<APValue> &V, const Expr *E) { 3570 assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements()); 3571 // FIXME: remove this APValue copy. 3572 Result = APValue(V.data(), V.size()); 3573 return true; 3574 } 3575 bool Success(const APValue &V, const Expr *E) { 3576 assert(V.isVector()); 3577 Result = V; 3578 return true; 3579 } 3580 bool ZeroInitialization(const Expr *E); 3581 3582 bool VisitUnaryReal(const UnaryOperator *E) 3583 { return Visit(E->getSubExpr()); } 3584 bool VisitCastExpr(const CastExpr* E); 3585 bool VisitInitListExpr(const InitListExpr *E); 3586 bool VisitUnaryImag(const UnaryOperator *E); 3587 // FIXME: Missing: unary -, unary ~, binary add/sub/mul/div, 3588 // binary comparisons, binary and/or/xor, 3589 // shufflevector, ExtVectorElementExpr 3590 }; 3591 } // end anonymous namespace 3592 3593 static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) { 3594 assert(E->isRValue() && E->getType()->isVectorType() &&"not a vector rvalue"); 3595 return VectorExprEvaluator(Info, Result).Visit(E); 3596 } 3597 3598 bool VectorExprEvaluator::VisitCastExpr(const CastExpr* E) { 3599 const VectorType *VTy = E->getType()->castAs<VectorType>(); 3600 unsigned NElts = VTy->getNumElements(); 3601 3602 const Expr *SE = E->getSubExpr(); 3603 QualType SETy = SE->getType(); 3604 3605 switch (E->getCastKind()) { 3606 case CK_VectorSplat: { 3607 APValue Val = APValue(); 3608 if (SETy->isIntegerType()) { 3609 APSInt IntResult; 3610 if (!EvaluateInteger(SE, IntResult, Info)) 3611 return false; 3612 Val = APValue(IntResult); 3613 } else if (SETy->isRealFloatingType()) { 3614 APFloat F(0.0); 3615 if (!EvaluateFloat(SE, F, Info)) 3616 return false; 3617 Val = APValue(F); 3618 } else { 3619 return Error(E); 3620 } 3621 3622 // Splat and create vector APValue. 3623 SmallVector<APValue, 4> Elts(NElts, Val); 3624 return Success(Elts, E); 3625 } 3626 case CK_BitCast: { 3627 // Evaluate the operand into an APInt we can extract from. 3628 llvm::APInt SValInt; 3629 if (!EvalAndBitcastToAPInt(Info, SE, SValInt)) 3630 return false; 3631 // Extract the elements 3632 QualType EltTy = VTy->getElementType(); 3633 unsigned EltSize = Info.Ctx.getTypeSize(EltTy); 3634 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); 3635 SmallVector<APValue, 4> Elts; 3636 if (EltTy->isRealFloatingType()) { 3637 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy); 3638 bool isIEESem = &Sem != &APFloat::PPCDoubleDouble; 3639 unsigned FloatEltSize = EltSize; 3640 if (&Sem == &APFloat::x87DoubleExtended) 3641 FloatEltSize = 80; 3642 for (unsigned i = 0; i < NElts; i++) { 3643 llvm::APInt Elt; 3644 if (BigEndian) 3645 Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize); 3646 else 3647 Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize); 3648 Elts.push_back(APValue(APFloat(Elt, isIEESem))); 3649 } 3650 } else if (EltTy->isIntegerType()) { 3651 for (unsigned i = 0; i < NElts; i++) { 3652 llvm::APInt Elt; 3653 if (BigEndian) 3654 Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize); 3655 else 3656 Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize); 3657 Elts.push_back(APValue(APSInt(Elt, EltTy->isSignedIntegerType()))); 3658 } 3659 } else { 3660 return Error(E); 3661 } 3662 return Success(Elts, E); 3663 } 3664 default: 3665 return ExprEvaluatorBaseTy::VisitCastExpr(E); 3666 } 3667 } 3668 3669 bool 3670 VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 3671 const VectorType *VT = E->getType()->castAs<VectorType>(); 3672 unsigned NumInits = E->getNumInits(); 3673 unsigned NumElements = VT->getNumElements(); 3674 3675 QualType EltTy = VT->getElementType(); 3676 SmallVector<APValue, 4> Elements; 3677 3678 // The number of initializers can be less than the number of 3679 // vector elements. For OpenCL, this can be due to nested vector 3680 // initialization. For GCC compatibility, missing trailing elements 3681 // should be initialized with zeroes. 3682 unsigned CountInits = 0, CountElts = 0; 3683 while (CountElts < NumElements) { 3684 // Handle nested vector initialization. 3685 if (CountInits < NumInits 3686 && E->getInit(CountInits)->getType()->isExtVectorType()) { 3687 APValue v; 3688 if (!EvaluateVector(E->getInit(CountInits), v, Info)) 3689 return Error(E); 3690 unsigned vlen = v.getVectorLength(); 3691 for (unsigned j = 0; j < vlen; j++) 3692 Elements.push_back(v.getVectorElt(j)); 3693 CountElts += vlen; 3694 } else if (EltTy->isIntegerType()) { 3695 llvm::APSInt sInt(32); 3696 if (CountInits < NumInits) { 3697 if (!EvaluateInteger(E->getInit(CountInits), sInt, Info)) 3698 return false; 3699 } else // trailing integer zero. 3700 sInt = Info.Ctx.MakeIntValue(0, EltTy); 3701 Elements.push_back(APValue(sInt)); 3702 CountElts++; 3703 } else { 3704 llvm::APFloat f(0.0); 3705 if (CountInits < NumInits) { 3706 if (!EvaluateFloat(E->getInit(CountInits), f, Info)) 3707 return false; 3708 } else // trailing float zero. 3709 f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)); 3710 Elements.push_back(APValue(f)); 3711 CountElts++; 3712 } 3713 CountInits++; 3714 } 3715 return Success(Elements, E); 3716 } 3717 3718 bool 3719 VectorExprEvaluator::ZeroInitialization(const Expr *E) { 3720 const VectorType *VT = E->getType()->getAs<VectorType>(); 3721 QualType EltTy = VT->getElementType(); 3722 APValue ZeroElement; 3723 if (EltTy->isIntegerType()) 3724 ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy)); 3725 else 3726 ZeroElement = 3727 APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy))); 3728 3729 SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement); 3730 return Success(Elements, E); 3731 } 3732 3733 bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 3734 VisitIgnoredValue(E->getSubExpr()); 3735 return ZeroInitialization(E); 3736 } 3737 3738 //===----------------------------------------------------------------------===// 3739 // Array Evaluation 3740 //===----------------------------------------------------------------------===// 3741 3742 namespace { 3743 class ArrayExprEvaluator 3744 : public ExprEvaluatorBase<ArrayExprEvaluator, bool> { 3745 const LValue &This; 3746 APValue &Result; 3747 public: 3748 3749 ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result) 3750 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {} 3751 3752 bool Success(const APValue &V, const Expr *E) { 3753 assert((V.isArray() || V.isLValue()) && 3754 "expected array or string literal"); 3755 Result = V; 3756 return true; 3757 } 3758 3759 bool ZeroInitialization(const Expr *E) { 3760 const ConstantArrayType *CAT = 3761 Info.Ctx.getAsConstantArrayType(E->getType()); 3762 if (!CAT) 3763 return Error(E); 3764 3765 Result = APValue(APValue::UninitArray(), 0, 3766 CAT->getSize().getZExtValue()); 3767 if (!Result.hasArrayFiller()) return true; 3768 3769 // Zero-initialize all elements. 3770 LValue Subobject = This; 3771 Subobject.addArray(Info, E, CAT); 3772 ImplicitValueInitExpr VIE(CAT->getElementType()); 3773 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE); 3774 } 3775 3776 bool VisitInitListExpr(const InitListExpr *E); 3777 bool VisitCXXConstructExpr(const CXXConstructExpr *E); 3778 }; 3779 } // end anonymous namespace 3780 3781 static bool EvaluateArray(const Expr *E, const LValue &This, 3782 APValue &Result, EvalInfo &Info) { 3783 assert(E->isRValue() && E->getType()->isArrayType() && "not an array rvalue"); 3784 return ArrayExprEvaluator(Info, This, Result).Visit(E); 3785 } 3786 3787 bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 3788 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(E->getType()); 3789 if (!CAT) 3790 return Error(E); 3791 3792 // C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...] 3793 // an appropriately-typed string literal enclosed in braces. 3794 if (E->isStringLiteralInit()) { 3795 LValue LV; 3796 if (!EvaluateLValue(E->getInit(0), LV, Info)) 3797 return false; 3798 APValue Val; 3799 LV.moveInto(Val); 3800 return Success(Val, E); 3801 } 3802 3803 bool Success = true; 3804 3805 assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) && 3806 "zero-initialized array shouldn't have any initialized elts"); 3807 APValue Filler; 3808 if (Result.isArray() && Result.hasArrayFiller()) 3809 Filler = Result.getArrayFiller(); 3810 3811 Result = APValue(APValue::UninitArray(), E->getNumInits(), 3812 CAT->getSize().getZExtValue()); 3813 3814 // If the array was previously zero-initialized, preserve the 3815 // zero-initialized values. 3816 if (!Filler.isUninit()) { 3817 for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I) 3818 Result.getArrayInitializedElt(I) = Filler; 3819 if (Result.hasArrayFiller()) 3820 Result.getArrayFiller() = Filler; 3821 } 3822 3823 LValue Subobject = This; 3824 Subobject.addArray(Info, E, CAT); 3825 unsigned Index = 0; 3826 for (InitListExpr::const_iterator I = E->begin(), End = E->end(); 3827 I != End; ++I, ++Index) { 3828 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), 3829 Info, Subobject, cast<Expr>(*I)) || 3830 !HandleLValueArrayAdjustment(Info, cast<Expr>(*I), Subobject, 3831 CAT->getElementType(), 1)) { 3832 if (!Info.keepEvaluatingAfterFailure()) 3833 return false; 3834 Success = false; 3835 } 3836 } 3837 3838 if (!Result.hasArrayFiller()) return Success; 3839 assert(E->hasArrayFiller() && "no array filler for incomplete init list"); 3840 // FIXME: The Subobject here isn't necessarily right. This rarely matters, 3841 // but sometimes does: 3842 // struct S { constexpr S() : p(&p) {} void *p; }; 3843 // S s[10] = {}; 3844 return EvaluateInPlace(Result.getArrayFiller(), Info, 3845 Subobject, E->getArrayFiller()) && Success; 3846 } 3847 3848 bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { 3849 // FIXME: The Subobject here isn't necessarily right. This rarely matters, 3850 // but sometimes does: 3851 // struct S { constexpr S() : p(&p) {} void *p; }; 3852 // S s[10]; 3853 LValue Subobject = This; 3854 3855 APValue *Value = &Result; 3856 bool HadZeroInit = true; 3857 QualType ElemTy = E->getType(); 3858 while (const ConstantArrayType *CAT = 3859 Info.Ctx.getAsConstantArrayType(ElemTy)) { 3860 Subobject.addArray(Info, E, CAT); 3861 HadZeroInit &= !Value->isUninit(); 3862 if (!HadZeroInit) 3863 *Value = APValue(APValue::UninitArray(), 0, CAT->getSize().getZExtValue()); 3864 if (!Value->hasArrayFiller()) 3865 return true; 3866 Value = &Value->getArrayFiller(); 3867 ElemTy = CAT->getElementType(); 3868 } 3869 3870 if (!ElemTy->isRecordType()) 3871 return Error(E); 3872 3873 const CXXConstructorDecl *FD = E->getConstructor(); 3874 3875 bool ZeroInit = E->requiresZeroInitialization(); 3876 if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { 3877 if (HadZeroInit) 3878 return true; 3879 3880 if (ZeroInit) { 3881 ImplicitValueInitExpr VIE(ElemTy); 3882 return EvaluateInPlace(*Value, Info, Subobject, &VIE); 3883 } 3884 3885 const CXXRecordDecl *RD = FD->getParent(); 3886 if (RD->isUnion()) 3887 *Value = APValue((FieldDecl*)0); 3888 else 3889 *Value = 3890 APValue(APValue::UninitStruct(), RD->getNumBases(), 3891 std::distance(RD->field_begin(), RD->field_end())); 3892 return true; 3893 } 3894 3895 const FunctionDecl *Definition = 0; 3896 FD->getBody(Definition); 3897 3898 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition)) 3899 return false; 3900 3901 if (ZeroInit && !HadZeroInit) { 3902 ImplicitValueInitExpr VIE(ElemTy); 3903 if (!EvaluateInPlace(*Value, Info, Subobject, &VIE)) 3904 return false; 3905 } 3906 3907 llvm::ArrayRef<const Expr*> Args(E->getArgs(), E->getNumArgs()); 3908 return HandleConstructorCall(E->getExprLoc(), Subobject, Args, 3909 cast<CXXConstructorDecl>(Definition), 3910 Info, *Value); 3911 } 3912 3913 //===----------------------------------------------------------------------===// 3914 // Integer Evaluation 3915 // 3916 // As a GNU extension, we support casting pointers to sufficiently-wide integer 3917 // types and back in constant folding. Integer values are thus represented 3918 // either as an integer-valued APValue, or as an lvalue-valued APValue. 3919 //===----------------------------------------------------------------------===// 3920 3921 namespace { 3922 class IntExprEvaluator 3923 : public ExprEvaluatorBase<IntExprEvaluator, bool> { 3924 APValue &Result; 3925 public: 3926 IntExprEvaluator(EvalInfo &info, APValue &result) 3927 : ExprEvaluatorBaseTy(info), Result(result) {} 3928 3929 bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) { 3930 assert(E->getType()->isIntegralOrEnumerationType() && 3931 "Invalid evaluation result."); 3932 assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() && 3933 "Invalid evaluation result."); 3934 assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && 3935 "Invalid evaluation result."); 3936 Result = APValue(SI); 3937 return true; 3938 } 3939 bool Success(const llvm::APSInt &SI, const Expr *E) { 3940 return Success(SI, E, Result); 3941 } 3942 3943 bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) { 3944 assert(E->getType()->isIntegralOrEnumerationType() && 3945 "Invalid evaluation result."); 3946 assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && 3947 "Invalid evaluation result."); 3948 Result = APValue(APSInt(I)); 3949 Result.getInt().setIsUnsigned( 3950 E->getType()->isUnsignedIntegerOrEnumerationType()); 3951 return true; 3952 } 3953 bool Success(const llvm::APInt &I, const Expr *E) { 3954 return Success(I, E, Result); 3955 } 3956 3957 bool Success(uint64_t Value, const Expr *E, APValue &Result) { 3958 assert(E->getType()->isIntegralOrEnumerationType() && 3959 "Invalid evaluation result."); 3960 Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType())); 3961 return true; 3962 } 3963 bool Success(uint64_t Value, const Expr *E) { 3964 return Success(Value, E, Result); 3965 } 3966 3967 bool Success(CharUnits Size, const Expr *E) { 3968 return Success(Size.getQuantity(), E); 3969 } 3970 3971 bool Success(const APValue &V, const Expr *E) { 3972 if (V.isLValue() || V.isAddrLabelDiff()) { 3973 Result = V; 3974 return true; 3975 } 3976 return Success(V.getInt(), E); 3977 } 3978 3979 bool ZeroInitialization(const Expr *E) { return Success(0, E); } 3980 3981 //===--------------------------------------------------------------------===// 3982 // Visitor Methods 3983 //===--------------------------------------------------------------------===// 3984 3985 bool VisitIntegerLiteral(const IntegerLiteral *E) { 3986 return Success(E->getValue(), E); 3987 } 3988 bool VisitCharacterLiteral(const CharacterLiteral *E) { 3989 return Success(E->getValue(), E); 3990 } 3991 3992 bool CheckReferencedDecl(const Expr *E, const Decl *D); 3993 bool VisitDeclRefExpr(const DeclRefExpr *E) { 3994 if (CheckReferencedDecl(E, E->getDecl())) 3995 return true; 3996 3997 return ExprEvaluatorBaseTy::VisitDeclRefExpr(E); 3998 } 3999 bool VisitMemberExpr(const MemberExpr *E) { 4000 if (CheckReferencedDecl(E, E->getMemberDecl())) { 4001 VisitIgnoredValue(E->getBase()); 4002 return true; 4003 } 4004 4005 return ExprEvaluatorBaseTy::VisitMemberExpr(E); 4006 } 4007 4008 bool VisitCallExpr(const CallExpr *E); 4009 bool VisitBinaryOperator(const BinaryOperator *E); 4010 bool VisitOffsetOfExpr(const OffsetOfExpr *E); 4011 bool VisitUnaryOperator(const UnaryOperator *E); 4012 4013 bool VisitCastExpr(const CastExpr* E); 4014 bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E); 4015 4016 bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) { 4017 return Success(E->getValue(), E); 4018 } 4019 4020 bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) { 4021 return Success(E->getValue(), E); 4022 } 4023 4024 // Note, GNU defines __null as an integer, not a pointer. 4025 bool VisitGNUNullExpr(const GNUNullExpr *E) { 4026 return ZeroInitialization(E); 4027 } 4028 4029 bool VisitUnaryTypeTraitExpr(const UnaryTypeTraitExpr *E) { 4030 return Success(E->getValue(), E); 4031 } 4032 4033 bool VisitBinaryTypeTraitExpr(const BinaryTypeTraitExpr *E) { 4034 return Success(E->getValue(), E); 4035 } 4036 4037 bool VisitTypeTraitExpr(const TypeTraitExpr *E) { 4038 return Success(E->getValue(), E); 4039 } 4040 4041 bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) { 4042 return Success(E->getValue(), E); 4043 } 4044 4045 bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) { 4046 return Success(E->getValue(), E); 4047 } 4048 4049 bool VisitUnaryReal(const UnaryOperator *E); 4050 bool VisitUnaryImag(const UnaryOperator *E); 4051 4052 bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E); 4053 bool VisitSizeOfPackExpr(const SizeOfPackExpr *E); 4054 4055 private: 4056 CharUnits GetAlignOfExpr(const Expr *E); 4057 CharUnits GetAlignOfType(QualType T); 4058 static QualType GetObjectType(APValue::LValueBase B); 4059 bool TryEvaluateBuiltinObjectSize(const CallExpr *E); 4060 // FIXME: Missing: array subscript of vector, member of vector 4061 }; 4062 } // end anonymous namespace 4063 4064 /// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and 4065 /// produce either the integer value or a pointer. 4066 /// 4067 /// GCC has a heinous extension which folds casts between pointer types and 4068 /// pointer-sized integral types. We support this by allowing the evaluation of 4069 /// an integer rvalue to produce a pointer (represented as an lvalue) instead. 4070 /// Some simple arithmetic on such values is supported (they are treated much 4071 /// like char*). 4072 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, 4073 EvalInfo &Info) { 4074 assert(E->isRValue() && E->getType()->isIntegralOrEnumerationType()); 4075 return IntExprEvaluator(Info, Result).Visit(E); 4076 } 4077 4078 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) { 4079 APValue Val; 4080 if (!EvaluateIntegerOrLValue(E, Val, Info)) 4081 return false; 4082 if (!Val.isInt()) { 4083 // FIXME: It would be better to produce the diagnostic for casting 4084 // a pointer to an integer. 4085 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 4086 return false; 4087 } 4088 Result = Val.getInt(); 4089 return true; 4090 } 4091 4092 /// Check whether the given declaration can be directly converted to an integral 4093 /// rvalue. If not, no diagnostic is produced; there are other things we can 4094 /// try. 4095 bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) { 4096 // Enums are integer constant exprs. 4097 if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) { 4098 // Check for signedness/width mismatches between E type and ECD value. 4099 bool SameSign = (ECD->getInitVal().isSigned() 4100 == E->getType()->isSignedIntegerOrEnumerationType()); 4101 bool SameWidth = (ECD->getInitVal().getBitWidth() 4102 == Info.Ctx.getIntWidth(E->getType())); 4103 if (SameSign && SameWidth) 4104 return Success(ECD->getInitVal(), E); 4105 else { 4106 // Get rid of mismatch (otherwise Success assertions will fail) 4107 // by computing a new value matching the type of E. 4108 llvm::APSInt Val = ECD->getInitVal(); 4109 if (!SameSign) 4110 Val.setIsSigned(!ECD->getInitVal().isSigned()); 4111 if (!SameWidth) 4112 Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType())); 4113 return Success(Val, E); 4114 } 4115 } 4116 return false; 4117 } 4118 4119 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way 4120 /// as GCC. 4121 static int EvaluateBuiltinClassifyType(const CallExpr *E) { 4122 // The following enum mimics the values returned by GCC. 4123 // FIXME: Does GCC differ between lvalue and rvalue references here? 4124 enum gcc_type_class { 4125 no_type_class = -1, 4126 void_type_class, integer_type_class, char_type_class, 4127 enumeral_type_class, boolean_type_class, 4128 pointer_type_class, reference_type_class, offset_type_class, 4129 real_type_class, complex_type_class, 4130 function_type_class, method_type_class, 4131 record_type_class, union_type_class, 4132 array_type_class, string_type_class, 4133 lang_type_class 4134 }; 4135 4136 // If no argument was supplied, default to "no_type_class". This isn't 4137 // ideal, however it is what gcc does. 4138 if (E->getNumArgs() == 0) 4139 return no_type_class; 4140 4141 QualType ArgTy = E->getArg(0)->getType(); 4142 if (ArgTy->isVoidType()) 4143 return void_type_class; 4144 else if (ArgTy->isEnumeralType()) 4145 return enumeral_type_class; 4146 else if (ArgTy->isBooleanType()) 4147 return boolean_type_class; 4148 else if (ArgTy->isCharType()) 4149 return string_type_class; // gcc doesn't appear to use char_type_class 4150 else if (ArgTy->isIntegerType()) 4151 return integer_type_class; 4152 else if (ArgTy->isPointerType()) 4153 return pointer_type_class; 4154 else if (ArgTy->isReferenceType()) 4155 return reference_type_class; 4156 else if (ArgTy->isRealType()) 4157 return real_type_class; 4158 else if (ArgTy->isComplexType()) 4159 return complex_type_class; 4160 else if (ArgTy->isFunctionType()) 4161 return function_type_class; 4162 else if (ArgTy->isStructureOrClassType()) 4163 return record_type_class; 4164 else if (ArgTy->isUnionType()) 4165 return union_type_class; 4166 else if (ArgTy->isArrayType()) 4167 return array_type_class; 4168 else if (ArgTy->isUnionType()) 4169 return union_type_class; 4170 else // FIXME: offset_type_class, method_type_class, & lang_type_class? 4171 llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type"); 4172 } 4173 4174 /// EvaluateBuiltinConstantPForLValue - Determine the result of 4175 /// __builtin_constant_p when applied to the given lvalue. 4176 /// 4177 /// An lvalue is only "constant" if it is a pointer or reference to the first 4178 /// character of a string literal. 4179 template<typename LValue> 4180 static bool EvaluateBuiltinConstantPForLValue(const LValue &LV) { 4181 const Expr *E = LV.getLValueBase().template dyn_cast<const Expr*>(); 4182 return E && isa<StringLiteral>(E) && LV.getLValueOffset().isZero(); 4183 } 4184 4185 /// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to 4186 /// GCC as we can manage. 4187 static bool EvaluateBuiltinConstantP(ASTContext &Ctx, const Expr *Arg) { 4188 QualType ArgType = Arg->getType(); 4189 4190 // __builtin_constant_p always has one operand. The rules which gcc follows 4191 // are not precisely documented, but are as follows: 4192 // 4193 // - If the operand is of integral, floating, complex or enumeration type, 4194 // and can be folded to a known value of that type, it returns 1. 4195 // - If the operand and can be folded to a pointer to the first character 4196 // of a string literal (or such a pointer cast to an integral type), it 4197 // returns 1. 4198 // 4199 // Otherwise, it returns 0. 4200 // 4201 // FIXME: GCC also intends to return 1 for literals of aggregate types, but 4202 // its support for this does not currently work. 4203 if (ArgType->isIntegralOrEnumerationType()) { 4204 Expr::EvalResult Result; 4205 if (!Arg->EvaluateAsRValue(Result, Ctx) || Result.HasSideEffects) 4206 return false; 4207 4208 APValue &V = Result.Val; 4209 if (V.getKind() == APValue::Int) 4210 return true; 4211 4212 return EvaluateBuiltinConstantPForLValue(V); 4213 } else if (ArgType->isFloatingType() || ArgType->isAnyComplexType()) { 4214 return Arg->isEvaluatable(Ctx); 4215 } else if (ArgType->isPointerType() || Arg->isGLValue()) { 4216 LValue LV; 4217 Expr::EvalStatus Status; 4218 EvalInfo Info(Ctx, Status); 4219 if ((Arg->isGLValue() ? EvaluateLValue(Arg, LV, Info) 4220 : EvaluatePointer(Arg, LV, Info)) && 4221 !Status.HasSideEffects) 4222 return EvaluateBuiltinConstantPForLValue(LV); 4223 } 4224 4225 // Anything else isn't considered to be sufficiently constant. 4226 return false; 4227 } 4228 4229 /// Retrieves the "underlying object type" of the given expression, 4230 /// as used by __builtin_object_size. 4231 QualType IntExprEvaluator::GetObjectType(APValue::LValueBase B) { 4232 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { 4233 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 4234 return VD->getType(); 4235 } else if (const Expr *E = B.get<const Expr*>()) { 4236 if (isa<CompoundLiteralExpr>(E)) 4237 return E->getType(); 4238 } 4239 4240 return QualType(); 4241 } 4242 4243 bool IntExprEvaluator::TryEvaluateBuiltinObjectSize(const CallExpr *E) { 4244 LValue Base; 4245 4246 { 4247 // The operand of __builtin_object_size is never evaluated for side-effects. 4248 // If there are any, but we can determine the pointed-to object anyway, then 4249 // ignore the side-effects. 4250 SpeculativeEvaluationRAII SpeculativeEval(Info); 4251 if (!EvaluatePointer(E->getArg(0), Base, Info)) 4252 return false; 4253 } 4254 4255 // If we can prove the base is null, lower to zero now. 4256 if (!Base.getLValueBase()) return Success(0, E); 4257 4258 QualType T = GetObjectType(Base.getLValueBase()); 4259 if (T.isNull() || 4260 T->isIncompleteType() || 4261 T->isFunctionType() || 4262 T->isVariablyModifiedType() || 4263 T->isDependentType()) 4264 return Error(E); 4265 4266 CharUnits Size = Info.Ctx.getTypeSizeInChars(T); 4267 CharUnits Offset = Base.getLValueOffset(); 4268 4269 if (!Offset.isNegative() && Offset <= Size) 4270 Size -= Offset; 4271 else 4272 Size = CharUnits::Zero(); 4273 return Success(Size, E); 4274 } 4275 4276 bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) { 4277 switch (unsigned BuiltinOp = E->isBuiltinCall()) { 4278 default: 4279 return ExprEvaluatorBaseTy::VisitCallExpr(E); 4280 4281 case Builtin::BI__builtin_object_size: { 4282 if (TryEvaluateBuiltinObjectSize(E)) 4283 return true; 4284 4285 // If evaluating the argument has side-effects, we can't determine the size 4286 // of the object, and so we lower it to unknown now. CodeGen relies on us to 4287 // handle all cases where the expression has side-effects. 4288 if (E->getArg(0)->HasSideEffects(Info.Ctx)) { 4289 if (E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue() <= 1) 4290 return Success(-1ULL, E); 4291 return Success(0, E); 4292 } 4293 4294 // Expression had no side effects, but we couldn't statically determine the 4295 // size of the referenced object. 4296 return Error(E); 4297 } 4298 4299 case Builtin::BI__builtin_classify_type: 4300 return Success(EvaluateBuiltinClassifyType(E), E); 4301 4302 case Builtin::BI__builtin_constant_p: 4303 return Success(EvaluateBuiltinConstantP(Info.Ctx, E->getArg(0)), E); 4304 4305 case Builtin::BI__builtin_eh_return_data_regno: { 4306 int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); 4307 Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand); 4308 return Success(Operand, E); 4309 } 4310 4311 case Builtin::BI__builtin_expect: 4312 return Visit(E->getArg(0)); 4313 4314 case Builtin::BIstrlen: 4315 // A call to strlen is not a constant expression. 4316 if (Info.getLangOpts().CPlusPlus0x) 4317 Info.CCEDiag(E, diag::note_constexpr_invalid_function) 4318 << /*isConstexpr*/0 << /*isConstructor*/0 << "'strlen'"; 4319 else 4320 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 4321 // Fall through. 4322 case Builtin::BI__builtin_strlen: 4323 // As an extension, we support strlen() and __builtin_strlen() as constant 4324 // expressions when the argument is a string literal. 4325 if (const StringLiteral *S 4326 = dyn_cast<StringLiteral>(E->getArg(0)->IgnoreParenImpCasts())) { 4327 // The string literal may have embedded null characters. Find the first 4328 // one and truncate there. 4329 StringRef Str = S->getString(); 4330 StringRef::size_type Pos = Str.find(0); 4331 if (Pos != StringRef::npos) 4332 Str = Str.substr(0, Pos); 4333 4334 return Success(Str.size(), E); 4335 } 4336 4337 return Error(E); 4338 4339 case Builtin::BI__atomic_always_lock_free: 4340 case Builtin::BI__atomic_is_lock_free: 4341 case Builtin::BI__c11_atomic_is_lock_free: { 4342 APSInt SizeVal; 4343 if (!EvaluateInteger(E->getArg(0), SizeVal, Info)) 4344 return false; 4345 4346 // For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power 4347 // of two less than the maximum inline atomic width, we know it is 4348 // lock-free. If the size isn't a power of two, or greater than the 4349 // maximum alignment where we promote atomics, we know it is not lock-free 4350 // (at least not in the sense of atomic_is_lock_free). Otherwise, 4351 // the answer can only be determined at runtime; for example, 16-byte 4352 // atomics have lock-free implementations on some, but not all, 4353 // x86-64 processors. 4354 4355 // Check power-of-two. 4356 CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue()); 4357 if (Size.isPowerOfTwo()) { 4358 // Check against inlining width. 4359 unsigned InlineWidthBits = 4360 Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth(); 4361 if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) { 4362 if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free || 4363 Size == CharUnits::One() || 4364 E->getArg(1)->isNullPointerConstant(Info.Ctx, 4365 Expr::NPC_NeverValueDependent)) 4366 // OK, we will inline appropriately-aligned operations of this size, 4367 // and _Atomic(T) is appropriately-aligned. 4368 return Success(1, E); 4369 4370 QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()-> 4371 castAs<PointerType>()->getPointeeType(); 4372 if (!PointeeType->isIncompleteType() && 4373 Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) { 4374 // OK, we will inline operations on this object. 4375 return Success(1, E); 4376 } 4377 } 4378 } 4379 4380 return BuiltinOp == Builtin::BI__atomic_always_lock_free ? 4381 Success(0, E) : Error(E); 4382 } 4383 } 4384 } 4385 4386 static bool HasSameBase(const LValue &A, const LValue &B) { 4387 if (!A.getLValueBase()) 4388 return !B.getLValueBase(); 4389 if (!B.getLValueBase()) 4390 return false; 4391 4392 if (A.getLValueBase().getOpaqueValue() != 4393 B.getLValueBase().getOpaqueValue()) { 4394 const Decl *ADecl = GetLValueBaseDecl(A); 4395 if (!ADecl) 4396 return false; 4397 const Decl *BDecl = GetLValueBaseDecl(B); 4398 if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl()) 4399 return false; 4400 } 4401 4402 return IsGlobalLValue(A.getLValueBase()) || 4403 A.getLValueCallIndex() == B.getLValueCallIndex(); 4404 } 4405 4406 /// Perform the given integer operation, which is known to need at most BitWidth 4407 /// bits, and check for overflow in the original type (if that type was not an 4408 /// unsigned type). 4409 template<typename Operation> 4410 static APSInt CheckedIntArithmetic(EvalInfo &Info, const Expr *E, 4411 const APSInt &LHS, const APSInt &RHS, 4412 unsigned BitWidth, Operation Op) { 4413 if (LHS.isUnsigned()) 4414 return Op(LHS, RHS); 4415 4416 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false); 4417 APSInt Result = Value.trunc(LHS.getBitWidth()); 4418 if (Result.extend(BitWidth) != Value) 4419 HandleOverflow(Info, E, Value, E->getType()); 4420 return Result; 4421 } 4422 4423 namespace { 4424 4425 /// \brief Data recursive integer evaluator of certain binary operators. 4426 /// 4427 /// We use a data recursive algorithm for binary operators so that we are able 4428 /// to handle extreme cases of chained binary operators without causing stack 4429 /// overflow. 4430 class DataRecursiveIntBinOpEvaluator { 4431 struct EvalResult { 4432 APValue Val; 4433 bool Failed; 4434 4435 EvalResult() : Failed(false) { } 4436 4437 void swap(EvalResult &RHS) { 4438 Val.swap(RHS.Val); 4439 Failed = RHS.Failed; 4440 RHS.Failed = false; 4441 } 4442 }; 4443 4444 struct Job { 4445 const Expr *E; 4446 EvalResult LHSResult; // meaningful only for binary operator expression. 4447 enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind; 4448 4449 Job() : StoredInfo(0) { } 4450 void startSpeculativeEval(EvalInfo &Info) { 4451 OldEvalStatus = Info.EvalStatus; 4452 Info.EvalStatus.Diag = 0; 4453 StoredInfo = &Info; 4454 } 4455 ~Job() { 4456 if (StoredInfo) { 4457 StoredInfo->EvalStatus = OldEvalStatus; 4458 } 4459 } 4460 private: 4461 EvalInfo *StoredInfo; // non-null if status changed. 4462 Expr::EvalStatus OldEvalStatus; 4463 }; 4464 4465 SmallVector<Job, 16> Queue; 4466 4467 IntExprEvaluator &IntEval; 4468 EvalInfo &Info; 4469 APValue &FinalResult; 4470 4471 public: 4472 DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result) 4473 : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { } 4474 4475 /// \brief True if \param E is a binary operator that we are going to handle 4476 /// data recursively. 4477 /// We handle binary operators that are comma, logical, or that have operands 4478 /// with integral or enumeration type. 4479 static bool shouldEnqueue(const BinaryOperator *E) { 4480 return E->getOpcode() == BO_Comma || 4481 E->isLogicalOp() || 4482 (E->getLHS()->getType()->isIntegralOrEnumerationType() && 4483 E->getRHS()->getType()->isIntegralOrEnumerationType()); 4484 } 4485 4486 bool Traverse(const BinaryOperator *E) { 4487 enqueue(E); 4488 EvalResult PrevResult; 4489 while (!Queue.empty()) 4490 process(PrevResult); 4491 4492 if (PrevResult.Failed) return false; 4493 4494 FinalResult.swap(PrevResult.Val); 4495 return true; 4496 } 4497 4498 private: 4499 bool Success(uint64_t Value, const Expr *E, APValue &Result) { 4500 return IntEval.Success(Value, E, Result); 4501 } 4502 bool Success(const APSInt &Value, const Expr *E, APValue &Result) { 4503 return IntEval.Success(Value, E, Result); 4504 } 4505 bool Error(const Expr *E) { 4506 return IntEval.Error(E); 4507 } 4508 bool Error(const Expr *E, diag::kind D) { 4509 return IntEval.Error(E, D); 4510 } 4511 4512 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { 4513 return Info.CCEDiag(E, D); 4514 } 4515 4516 // \brief Returns true if visiting the RHS is necessary, false otherwise. 4517 bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, 4518 bool &SuppressRHSDiags); 4519 4520 bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, 4521 const BinaryOperator *E, APValue &Result); 4522 4523 void EvaluateExpr(const Expr *E, EvalResult &Result) { 4524 Result.Failed = !Evaluate(Result.Val, Info, E); 4525 if (Result.Failed) 4526 Result.Val = APValue(); 4527 } 4528 4529 void process(EvalResult &Result); 4530 4531 void enqueue(const Expr *E) { 4532 E = E->IgnoreParens(); 4533 Queue.resize(Queue.size()+1); 4534 Queue.back().E = E; 4535 Queue.back().Kind = Job::AnyExprKind; 4536 } 4537 }; 4538 4539 } 4540 4541 bool DataRecursiveIntBinOpEvaluator:: 4542 VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, 4543 bool &SuppressRHSDiags) { 4544 if (E->getOpcode() == BO_Comma) { 4545 // Ignore LHS but note if we could not evaluate it. 4546 if (LHSResult.Failed) 4547 Info.EvalStatus.HasSideEffects = true; 4548 return true; 4549 } 4550 4551 if (E->isLogicalOp()) { 4552 bool lhsResult; 4553 if (HandleConversionToBool(LHSResult.Val, lhsResult)) { 4554 // We were able to evaluate the LHS, see if we can get away with not 4555 // evaluating the RHS: 0 && X -> 0, 1 || X -> 1 4556 if (lhsResult == (E->getOpcode() == BO_LOr)) { 4557 Success(lhsResult, E, LHSResult.Val); 4558 return false; // Ignore RHS 4559 } 4560 } else { 4561 // Since we weren't able to evaluate the left hand side, it 4562 // must have had side effects. 4563 Info.EvalStatus.HasSideEffects = true; 4564 4565 // We can't evaluate the LHS; however, sometimes the result 4566 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. 4567 // Don't ignore RHS and suppress diagnostics from this arm. 4568 SuppressRHSDiags = true; 4569 } 4570 4571 return true; 4572 } 4573 4574 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && 4575 E->getRHS()->getType()->isIntegralOrEnumerationType()); 4576 4577 if (LHSResult.Failed && !Info.keepEvaluatingAfterFailure()) 4578 return false; // Ignore RHS; 4579 4580 return true; 4581 } 4582 4583 bool DataRecursiveIntBinOpEvaluator:: 4584 VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, 4585 const BinaryOperator *E, APValue &Result) { 4586 if (E->getOpcode() == BO_Comma) { 4587 if (RHSResult.Failed) 4588 return false; 4589 Result = RHSResult.Val; 4590 return true; 4591 } 4592 4593 if (E->isLogicalOp()) { 4594 bool lhsResult, rhsResult; 4595 bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult); 4596 bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult); 4597 4598 if (LHSIsOK) { 4599 if (RHSIsOK) { 4600 if (E->getOpcode() == BO_LOr) 4601 return Success(lhsResult || rhsResult, E, Result); 4602 else 4603 return Success(lhsResult && rhsResult, E, Result); 4604 } 4605 } else { 4606 if (RHSIsOK) { 4607 // We can't evaluate the LHS; however, sometimes the result 4608 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. 4609 if (rhsResult == (E->getOpcode() == BO_LOr)) 4610 return Success(rhsResult, E, Result); 4611 } 4612 } 4613 4614 return false; 4615 } 4616 4617 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && 4618 E->getRHS()->getType()->isIntegralOrEnumerationType()); 4619 4620 if (LHSResult.Failed || RHSResult.Failed) 4621 return false; 4622 4623 const APValue &LHSVal = LHSResult.Val; 4624 const APValue &RHSVal = RHSResult.Val; 4625 4626 // Handle cases like (unsigned long)&a + 4. 4627 if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) { 4628 Result = LHSVal; 4629 CharUnits AdditionalOffset = CharUnits::fromQuantity( 4630 RHSVal.getInt().getZExtValue()); 4631 if (E->getOpcode() == BO_Add) 4632 Result.getLValueOffset() += AdditionalOffset; 4633 else 4634 Result.getLValueOffset() -= AdditionalOffset; 4635 return true; 4636 } 4637 4638 // Handle cases like 4 + (unsigned long)&a 4639 if (E->getOpcode() == BO_Add && 4640 RHSVal.isLValue() && LHSVal.isInt()) { 4641 Result = RHSVal; 4642 Result.getLValueOffset() += CharUnits::fromQuantity( 4643 LHSVal.getInt().getZExtValue()); 4644 return true; 4645 } 4646 4647 if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) { 4648 // Handle (intptr_t)&&A - (intptr_t)&&B. 4649 if (!LHSVal.getLValueOffset().isZero() || 4650 !RHSVal.getLValueOffset().isZero()) 4651 return false; 4652 const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>(); 4653 const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>(); 4654 if (!LHSExpr || !RHSExpr) 4655 return false; 4656 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); 4657 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); 4658 if (!LHSAddrExpr || !RHSAddrExpr) 4659 return false; 4660 // Make sure both labels come from the same function. 4661 if (LHSAddrExpr->getLabel()->getDeclContext() != 4662 RHSAddrExpr->getLabel()->getDeclContext()) 4663 return false; 4664 Result = APValue(LHSAddrExpr, RHSAddrExpr); 4665 return true; 4666 } 4667 4668 // All the following cases expect both operands to be an integer 4669 if (!LHSVal.isInt() || !RHSVal.isInt()) 4670 return Error(E); 4671 4672 const APSInt &LHS = LHSVal.getInt(); 4673 APSInt RHS = RHSVal.getInt(); 4674 4675 switch (E->getOpcode()) { 4676 default: 4677 return Error(E); 4678 case BO_Mul: 4679 return Success(CheckedIntArithmetic(Info, E, LHS, RHS, 4680 LHS.getBitWidth() * 2, 4681 std::multiplies<APSInt>()), E, 4682 Result); 4683 case BO_Add: 4684 return Success(CheckedIntArithmetic(Info, E, LHS, RHS, 4685 LHS.getBitWidth() + 1, 4686 std::plus<APSInt>()), E, Result); 4687 case BO_Sub: 4688 return Success(CheckedIntArithmetic(Info, E, LHS, RHS, 4689 LHS.getBitWidth() + 1, 4690 std::minus<APSInt>()), E, Result); 4691 case BO_And: return Success(LHS & RHS, E, Result); 4692 case BO_Xor: return Success(LHS ^ RHS, E, Result); 4693 case BO_Or: return Success(LHS | RHS, E, Result); 4694 case BO_Div: 4695 case BO_Rem: 4696 if (RHS == 0) 4697 return Error(E, diag::note_expr_divide_by_zero); 4698 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. The latter is 4699 // not actually undefined behavior in C++11 due to a language defect. 4700 if (RHS.isNegative() && RHS.isAllOnesValue() && 4701 LHS.isSigned() && LHS.isMinSignedValue()) 4702 HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType()); 4703 return Success(E->getOpcode() == BO_Rem ? LHS % RHS : LHS / RHS, E, 4704 Result); 4705 case BO_Shl: { 4706 // During constant-folding, a negative shift is an opposite shift. Such 4707 // a shift is not a constant expression. 4708 if (RHS.isSigned() && RHS.isNegative()) { 4709 CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; 4710 RHS = -RHS; 4711 goto shift_right; 4712 } 4713 4714 shift_left: 4715 // C++11 [expr.shift]p1: Shift width must be less than the bit width of 4716 // the shifted type. 4717 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); 4718 if (SA != RHS) { 4719 CCEDiag(E, diag::note_constexpr_large_shift) 4720 << RHS << E->getType() << LHS.getBitWidth(); 4721 } else if (LHS.isSigned()) { 4722 // C++11 [expr.shift]p2: A signed left shift must have a non-negative 4723 // operand, and must not overflow the corresponding unsigned type. 4724 if (LHS.isNegative()) 4725 CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS; 4726 else if (LHS.countLeadingZeros() < SA) 4727 CCEDiag(E, diag::note_constexpr_lshift_discards); 4728 } 4729 4730 return Success(LHS << SA, E, Result); 4731 } 4732 case BO_Shr: { 4733 // During constant-folding, a negative shift is an opposite shift. Such a 4734 // shift is not a constant expression. 4735 if (RHS.isSigned() && RHS.isNegative()) { 4736 CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; 4737 RHS = -RHS; 4738 goto shift_left; 4739 } 4740 4741 shift_right: 4742 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the 4743 // shifted type. 4744 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); 4745 if (SA != RHS) 4746 CCEDiag(E, diag::note_constexpr_large_shift) 4747 << RHS << E->getType() << LHS.getBitWidth(); 4748 4749 return Success(LHS >> SA, E, Result); 4750 } 4751 4752 case BO_LT: return Success(LHS < RHS, E, Result); 4753 case BO_GT: return Success(LHS > RHS, E, Result); 4754 case BO_LE: return Success(LHS <= RHS, E, Result); 4755 case BO_GE: return Success(LHS >= RHS, E, Result); 4756 case BO_EQ: return Success(LHS == RHS, E, Result); 4757 case BO_NE: return Success(LHS != RHS, E, Result); 4758 } 4759 } 4760 4761 void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) { 4762 Job &job = Queue.back(); 4763 4764 switch (job.Kind) { 4765 case Job::AnyExprKind: { 4766 if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) { 4767 if (shouldEnqueue(Bop)) { 4768 job.Kind = Job::BinOpKind; 4769 enqueue(Bop->getLHS()); 4770 return; 4771 } 4772 } 4773 4774 EvaluateExpr(job.E, Result); 4775 Queue.pop_back(); 4776 return; 4777 } 4778 4779 case Job::BinOpKind: { 4780 const BinaryOperator *Bop = cast<BinaryOperator>(job.E); 4781 bool SuppressRHSDiags = false; 4782 if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) { 4783 Queue.pop_back(); 4784 return; 4785 } 4786 if (SuppressRHSDiags) 4787 job.startSpeculativeEval(Info); 4788 job.LHSResult.swap(Result); 4789 job.Kind = Job::BinOpVisitedLHSKind; 4790 enqueue(Bop->getRHS()); 4791 return; 4792 } 4793 4794 case Job::BinOpVisitedLHSKind: { 4795 const BinaryOperator *Bop = cast<BinaryOperator>(job.E); 4796 EvalResult RHS; 4797 RHS.swap(Result); 4798 Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val); 4799 Queue.pop_back(); 4800 return; 4801 } 4802 } 4803 4804 llvm_unreachable("Invalid Job::Kind!"); 4805 } 4806 4807 bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 4808 if (E->isAssignmentOp()) 4809 return Error(E); 4810 4811 if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E)) 4812 return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E); 4813 4814 QualType LHSTy = E->getLHS()->getType(); 4815 QualType RHSTy = E->getRHS()->getType(); 4816 4817 if (LHSTy->isAnyComplexType()) { 4818 assert(RHSTy->isAnyComplexType() && "Invalid comparison"); 4819 ComplexValue LHS, RHS; 4820 4821 bool LHSOK = EvaluateComplex(E->getLHS(), LHS, Info); 4822 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 4823 return false; 4824 4825 if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) 4826 return false; 4827 4828 if (LHS.isComplexFloat()) { 4829 APFloat::cmpResult CR_r = 4830 LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal()); 4831 APFloat::cmpResult CR_i = 4832 LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag()); 4833 4834 if (E->getOpcode() == BO_EQ) 4835 return Success((CR_r == APFloat::cmpEqual && 4836 CR_i == APFloat::cmpEqual), E); 4837 else { 4838 assert(E->getOpcode() == BO_NE && 4839 "Invalid complex comparison."); 4840 return Success(((CR_r == APFloat::cmpGreaterThan || 4841 CR_r == APFloat::cmpLessThan || 4842 CR_r == APFloat::cmpUnordered) || 4843 (CR_i == APFloat::cmpGreaterThan || 4844 CR_i == APFloat::cmpLessThan || 4845 CR_i == APFloat::cmpUnordered)), E); 4846 } 4847 } else { 4848 if (E->getOpcode() == BO_EQ) 4849 return Success((LHS.getComplexIntReal() == RHS.getComplexIntReal() && 4850 LHS.getComplexIntImag() == RHS.getComplexIntImag()), E); 4851 else { 4852 assert(E->getOpcode() == BO_NE && 4853 "Invalid compex comparison."); 4854 return Success((LHS.getComplexIntReal() != RHS.getComplexIntReal() || 4855 LHS.getComplexIntImag() != RHS.getComplexIntImag()), E); 4856 } 4857 } 4858 } 4859 4860 if (LHSTy->isRealFloatingType() && 4861 RHSTy->isRealFloatingType()) { 4862 APFloat RHS(0.0), LHS(0.0); 4863 4864 bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info); 4865 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 4866 return false; 4867 4868 if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK) 4869 return false; 4870 4871 APFloat::cmpResult CR = LHS.compare(RHS); 4872 4873 switch (E->getOpcode()) { 4874 default: 4875 llvm_unreachable("Invalid binary operator!"); 4876 case BO_LT: 4877 return Success(CR == APFloat::cmpLessThan, E); 4878 case BO_GT: 4879 return Success(CR == APFloat::cmpGreaterThan, E); 4880 case BO_LE: 4881 return Success(CR == APFloat::cmpLessThan || CR == APFloat::cmpEqual, E); 4882 case BO_GE: 4883 return Success(CR == APFloat::cmpGreaterThan || CR == APFloat::cmpEqual, 4884 E); 4885 case BO_EQ: 4886 return Success(CR == APFloat::cmpEqual, E); 4887 case BO_NE: 4888 return Success(CR == APFloat::cmpGreaterThan 4889 || CR == APFloat::cmpLessThan 4890 || CR == APFloat::cmpUnordered, E); 4891 } 4892 } 4893 4894 if (LHSTy->isPointerType() && RHSTy->isPointerType()) { 4895 if (E->getOpcode() == BO_Sub || E->isComparisonOp()) { 4896 LValue LHSValue, RHSValue; 4897 4898 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); 4899 if (!LHSOK && Info.keepEvaluatingAfterFailure()) 4900 return false; 4901 4902 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK) 4903 return false; 4904 4905 // Reject differing bases from the normal codepath; we special-case 4906 // comparisons to null. 4907 if (!HasSameBase(LHSValue, RHSValue)) { 4908 if (E->getOpcode() == BO_Sub) { 4909 // Handle &&A - &&B. 4910 if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero()) 4911 return false; 4912 const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr*>(); 4913 const Expr *RHSExpr = LHSValue.Base.dyn_cast<const Expr*>(); 4914 if (!LHSExpr || !RHSExpr) 4915 return false; 4916 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); 4917 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); 4918 if (!LHSAddrExpr || !RHSAddrExpr) 4919 return false; 4920 // Make sure both labels come from the same function. 4921 if (LHSAddrExpr->getLabel()->getDeclContext() != 4922 RHSAddrExpr->getLabel()->getDeclContext()) 4923 return false; 4924 Result = APValue(LHSAddrExpr, RHSAddrExpr); 4925 return true; 4926 } 4927 // Inequalities and subtractions between unrelated pointers have 4928 // unspecified or undefined behavior. 4929 if (!E->isEqualityOp()) 4930 return Error(E); 4931 // A constant address may compare equal to the address of a symbol. 4932 // The one exception is that address of an object cannot compare equal 4933 // to a null pointer constant. 4934 if ((!LHSValue.Base && !LHSValue.Offset.isZero()) || 4935 (!RHSValue.Base && !RHSValue.Offset.isZero())) 4936 return Error(E); 4937 // It's implementation-defined whether distinct literals will have 4938 // distinct addresses. In clang, the result of such a comparison is 4939 // unspecified, so it is not a constant expression. However, we do know 4940 // that the address of a literal will be non-null. 4941 if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) && 4942 LHSValue.Base && RHSValue.Base) 4943 return Error(E); 4944 // We can't tell whether weak symbols will end up pointing to the same 4945 // object. 4946 if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue)) 4947 return Error(E); 4948 // Pointers with different bases cannot represent the same object. 4949 // (Note that clang defaults to -fmerge-all-constants, which can 4950 // lead to inconsistent results for comparisons involving the address 4951 // of a constant; this generally doesn't matter in practice.) 4952 return Success(E->getOpcode() == BO_NE, E); 4953 } 4954 4955 const CharUnits &LHSOffset = LHSValue.getLValueOffset(); 4956 const CharUnits &RHSOffset = RHSValue.getLValueOffset(); 4957 4958 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); 4959 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); 4960 4961 if (E->getOpcode() == BO_Sub) { 4962 // C++11 [expr.add]p6: 4963 // Unless both pointers point to elements of the same array object, or 4964 // one past the last element of the array object, the behavior is 4965 // undefined. 4966 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && 4967 !AreElementsOfSameArray(getType(LHSValue.Base), 4968 LHSDesignator, RHSDesignator)) 4969 CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array); 4970 4971 QualType Type = E->getLHS()->getType(); 4972 QualType ElementType = Type->getAs<PointerType>()->getPointeeType(); 4973 4974 CharUnits ElementSize; 4975 if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize)) 4976 return false; 4977 4978 // FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime, 4979 // and produce incorrect results when it overflows. Such behavior 4980 // appears to be non-conforming, but is common, so perhaps we should 4981 // assume the standard intended for such cases to be undefined behavior 4982 // and check for them. 4983 4984 // Compute (LHSOffset - RHSOffset) / Size carefully, checking for 4985 // overflow in the final conversion to ptrdiff_t. 4986 APSInt LHS( 4987 llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false); 4988 APSInt RHS( 4989 llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false); 4990 APSInt ElemSize( 4991 llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true), false); 4992 APSInt TrueResult = (LHS - RHS) / ElemSize; 4993 APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType())); 4994 4995 if (Result.extend(65) != TrueResult) 4996 HandleOverflow(Info, E, TrueResult, E->getType()); 4997 return Success(Result, E); 4998 } 4999 5000 // C++11 [expr.rel]p3: 5001 // Pointers to void (after pointer conversions) can be compared, with a 5002 // result defined as follows: If both pointers represent the same 5003 // address or are both the null pointer value, the result is true if the 5004 // operator is <= or >= and false otherwise; otherwise the result is 5005 // unspecified. 5006 // We interpret this as applying to pointers to *cv* void. 5007 if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && 5008 E->isRelationalOp()) 5009 CCEDiag(E, diag::note_constexpr_void_comparison); 5010 5011 // C++11 [expr.rel]p2: 5012 // - If two pointers point to non-static data members of the same object, 5013 // or to subobjects or array elements fo such members, recursively, the 5014 // pointer to the later declared member compares greater provided the 5015 // two members have the same access control and provided their class is 5016 // not a union. 5017 // [...] 5018 // - Otherwise pointer comparisons are unspecified. 5019 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && 5020 E->isRelationalOp()) { 5021 bool WasArrayIndex; 5022 unsigned Mismatch = 5023 FindDesignatorMismatch(getType(LHSValue.Base), LHSDesignator, 5024 RHSDesignator, WasArrayIndex); 5025 // At the point where the designators diverge, the comparison has a 5026 // specified value if: 5027 // - we are comparing array indices 5028 // - we are comparing fields of a union, or fields with the same access 5029 // Otherwise, the result is unspecified and thus the comparison is not a 5030 // constant expression. 5031 if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() && 5032 Mismatch < RHSDesignator.Entries.size()) { 5033 const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]); 5034 const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]); 5035 if (!LF && !RF) 5036 CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes); 5037 else if (!LF) 5038 CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) 5039 << getAsBaseClass(LHSDesignator.Entries[Mismatch]) 5040 << RF->getParent() << RF; 5041 else if (!RF) 5042 CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) 5043 << getAsBaseClass(RHSDesignator.Entries[Mismatch]) 5044 << LF->getParent() << LF; 5045 else if (!LF->getParent()->isUnion() && 5046 LF->getAccess() != RF->getAccess()) 5047 CCEDiag(E, diag::note_constexpr_pointer_comparison_differing_access) 5048 << LF << LF->getAccess() << RF << RF->getAccess() 5049 << LF->getParent(); 5050 } 5051 } 5052 5053 // The comparison here must be unsigned, and performed with the same 5054 // width as the pointer. 5055 unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy); 5056 uint64_t CompareLHS = LHSOffset.getQuantity(); 5057 uint64_t CompareRHS = RHSOffset.getQuantity(); 5058 assert(PtrSize <= 64 && "Unexpected pointer width"); 5059 uint64_t Mask = ~0ULL >> (64 - PtrSize); 5060 CompareLHS &= Mask; 5061 CompareRHS &= Mask; 5062 5063 // If there is a base and this is a relational operator, we can only 5064 // compare pointers within the object in question; otherwise, the result 5065 // depends on where the object is located in memory. 5066 if (!LHSValue.Base.isNull() && E->isRelationalOp()) { 5067 QualType BaseTy = getType(LHSValue.Base); 5068 if (BaseTy->isIncompleteType()) 5069 return Error(E); 5070 CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy); 5071 uint64_t OffsetLimit = Size.getQuantity(); 5072 if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit) 5073 return Error(E); 5074 } 5075 5076 switch (E->getOpcode()) { 5077 default: llvm_unreachable("missing comparison operator"); 5078 case BO_LT: return Success(CompareLHS < CompareRHS, E); 5079 case BO_GT: return Success(CompareLHS > CompareRHS, E); 5080 case BO_LE: return Success(CompareLHS <= CompareRHS, E); 5081 case BO_GE: return Success(CompareLHS >= CompareRHS, E); 5082 case BO_EQ: return Success(CompareLHS == CompareRHS, E); 5083 case BO_NE: return Success(CompareLHS != CompareRHS, E); 5084 } 5085 } 5086 } 5087 5088 if (LHSTy->isMemberPointerType()) { 5089 assert(E->isEqualityOp() && "unexpected member pointer operation"); 5090 assert(RHSTy->isMemberPointerType() && "invalid comparison"); 5091 5092 MemberPtr LHSValue, RHSValue; 5093 5094 bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info); 5095 if (!LHSOK && Info.keepEvaluatingAfterFailure()) 5096 return false; 5097 5098 if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK) 5099 return false; 5100 5101 // C++11 [expr.eq]p2: 5102 // If both operands are null, they compare equal. Otherwise if only one is 5103 // null, they compare unequal. 5104 if (!LHSValue.getDecl() || !RHSValue.getDecl()) { 5105 bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl(); 5106 return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E); 5107 } 5108 5109 // Otherwise if either is a pointer to a virtual member function, the 5110 // result is unspecified. 5111 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl())) 5112 if (MD->isVirtual()) 5113 CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; 5114 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl())) 5115 if (MD->isVirtual()) 5116 CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; 5117 5118 // Otherwise they compare equal if and only if they would refer to the 5119 // same member of the same most derived object or the same subobject if 5120 // they were dereferenced with a hypothetical object of the associated 5121 // class type. 5122 bool Equal = LHSValue == RHSValue; 5123 return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E); 5124 } 5125 5126 if (LHSTy->isNullPtrType()) { 5127 assert(E->isComparisonOp() && "unexpected nullptr operation"); 5128 assert(RHSTy->isNullPtrType() && "missing pointer conversion"); 5129 // C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t 5130 // are compared, the result is true of the operator is <=, >= or ==, and 5131 // false otherwise. 5132 BinaryOperator::Opcode Opcode = E->getOpcode(); 5133 return Success(Opcode == BO_EQ || Opcode == BO_LE || Opcode == BO_GE, E); 5134 } 5135 5136 assert((!LHSTy->isIntegralOrEnumerationType() || 5137 !RHSTy->isIntegralOrEnumerationType()) && 5138 "DataRecursiveIntBinOpEvaluator should have handled integral types"); 5139 // We can't continue from here for non-integral types. 5140 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 5141 } 5142 5143 CharUnits IntExprEvaluator::GetAlignOfType(QualType T) { 5144 // C++ [expr.alignof]p3: "When alignof is applied to a reference type, the 5145 // result shall be the alignment of the referenced type." 5146 if (const ReferenceType *Ref = T->getAs<ReferenceType>()) 5147 T = Ref->getPointeeType(); 5148 5149 // __alignof is defined to return the preferred alignment. 5150 return Info.Ctx.toCharUnitsFromBits( 5151 Info.Ctx.getPreferredTypeAlign(T.getTypePtr())); 5152 } 5153 5154 CharUnits IntExprEvaluator::GetAlignOfExpr(const Expr *E) { 5155 E = E->IgnoreParens(); 5156 5157 // alignof decl is always accepted, even if it doesn't make sense: we default 5158 // to 1 in those cases. 5159 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) 5160 return Info.Ctx.getDeclAlign(DRE->getDecl(), 5161 /*RefAsPointee*/true); 5162 5163 if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) 5164 return Info.Ctx.getDeclAlign(ME->getMemberDecl(), 5165 /*RefAsPointee*/true); 5166 5167 return GetAlignOfType(E->getType()); 5168 } 5169 5170 5171 /// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with 5172 /// a result as the expression's type. 5173 bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr( 5174 const UnaryExprOrTypeTraitExpr *E) { 5175 switch(E->getKind()) { 5176 case UETT_AlignOf: { 5177 if (E->isArgumentType()) 5178 return Success(GetAlignOfType(E->getArgumentType()), E); 5179 else 5180 return Success(GetAlignOfExpr(E->getArgumentExpr()), E); 5181 } 5182 5183 case UETT_VecStep: { 5184 QualType Ty = E->getTypeOfArgument(); 5185 5186 if (Ty->isVectorType()) { 5187 unsigned n = Ty->castAs<VectorType>()->getNumElements(); 5188 5189 // The vec_step built-in functions that take a 3-component 5190 // vector return 4. (OpenCL 1.1 spec 6.11.12) 5191 if (n == 3) 5192 n = 4; 5193 5194 return Success(n, E); 5195 } else 5196 return Success(1, E); 5197 } 5198 5199 case UETT_SizeOf: { 5200 QualType SrcTy = E->getTypeOfArgument(); 5201 // C++ [expr.sizeof]p2: "When applied to a reference or a reference type, 5202 // the result is the size of the referenced type." 5203 if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>()) 5204 SrcTy = Ref->getPointeeType(); 5205 5206 CharUnits Sizeof; 5207 if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof)) 5208 return false; 5209 return Success(Sizeof, E); 5210 } 5211 } 5212 5213 llvm_unreachable("unknown expr/type trait"); 5214 } 5215 5216 bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) { 5217 CharUnits Result; 5218 unsigned n = OOE->getNumComponents(); 5219 if (n == 0) 5220 return Error(OOE); 5221 QualType CurrentType = OOE->getTypeSourceInfo()->getType(); 5222 for (unsigned i = 0; i != n; ++i) { 5223 OffsetOfExpr::OffsetOfNode ON = OOE->getComponent(i); 5224 switch (ON.getKind()) { 5225 case OffsetOfExpr::OffsetOfNode::Array: { 5226 const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex()); 5227 APSInt IdxResult; 5228 if (!EvaluateInteger(Idx, IdxResult, Info)) 5229 return false; 5230 const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType); 5231 if (!AT) 5232 return Error(OOE); 5233 CurrentType = AT->getElementType(); 5234 CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType); 5235 Result += IdxResult.getSExtValue() * ElementSize; 5236 break; 5237 } 5238 5239 case OffsetOfExpr::OffsetOfNode::Field: { 5240 FieldDecl *MemberDecl = ON.getField(); 5241 const RecordType *RT = CurrentType->getAs<RecordType>(); 5242 if (!RT) 5243 return Error(OOE); 5244 RecordDecl *RD = RT->getDecl(); 5245 if (RD->isInvalidDecl()) return false; 5246 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); 5247 unsigned i = MemberDecl->getFieldIndex(); 5248 assert(i < RL.getFieldCount() && "offsetof field in wrong type"); 5249 Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i)); 5250 CurrentType = MemberDecl->getType().getNonReferenceType(); 5251 break; 5252 } 5253 5254 case OffsetOfExpr::OffsetOfNode::Identifier: 5255 llvm_unreachable("dependent __builtin_offsetof"); 5256 5257 case OffsetOfExpr::OffsetOfNode::Base: { 5258 CXXBaseSpecifier *BaseSpec = ON.getBase(); 5259 if (BaseSpec->isVirtual()) 5260 return Error(OOE); 5261 5262 // Find the layout of the class whose base we are looking into. 5263 const RecordType *RT = CurrentType->getAs<RecordType>(); 5264 if (!RT) 5265 return Error(OOE); 5266 RecordDecl *RD = RT->getDecl(); 5267 if (RD->isInvalidDecl()) return false; 5268 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); 5269 5270 // Find the base class itself. 5271 CurrentType = BaseSpec->getType(); 5272 const RecordType *BaseRT = CurrentType->getAs<RecordType>(); 5273 if (!BaseRT) 5274 return Error(OOE); 5275 5276 // Add the offset to the base. 5277 Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl())); 5278 break; 5279 } 5280 } 5281 } 5282 return Success(Result, OOE); 5283 } 5284 5285 bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 5286 switch (E->getOpcode()) { 5287 default: 5288 // Address, indirect, pre/post inc/dec, etc are not valid constant exprs. 5289 // See C99 6.6p3. 5290 return Error(E); 5291 case UO_Extension: 5292 // FIXME: Should extension allow i-c-e extension expressions in its scope? 5293 // If so, we could clear the diagnostic ID. 5294 return Visit(E->getSubExpr()); 5295 case UO_Plus: 5296 // The result is just the value. 5297 return Visit(E->getSubExpr()); 5298 case UO_Minus: { 5299 if (!Visit(E->getSubExpr())) 5300 return false; 5301 if (!Result.isInt()) return Error(E); 5302 const APSInt &Value = Result.getInt(); 5303 if (Value.isSigned() && Value.isMinSignedValue()) 5304 HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1), 5305 E->getType()); 5306 return Success(-Value, E); 5307 } 5308 case UO_Not: { 5309 if (!Visit(E->getSubExpr())) 5310 return false; 5311 if (!Result.isInt()) return Error(E); 5312 return Success(~Result.getInt(), E); 5313 } 5314 case UO_LNot: { 5315 bool bres; 5316 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info)) 5317 return false; 5318 return Success(!bres, E); 5319 } 5320 } 5321 } 5322 5323 /// HandleCast - This is used to evaluate implicit or explicit casts where the 5324 /// result type is integer. 5325 bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) { 5326 const Expr *SubExpr = E->getSubExpr(); 5327 QualType DestType = E->getType(); 5328 QualType SrcType = SubExpr->getType(); 5329 5330 switch (E->getCastKind()) { 5331 case CK_BaseToDerived: 5332 case CK_DerivedToBase: 5333 case CK_UncheckedDerivedToBase: 5334 case CK_Dynamic: 5335 case CK_ToUnion: 5336 case CK_ArrayToPointerDecay: 5337 case CK_FunctionToPointerDecay: 5338 case CK_NullToPointer: 5339 case CK_NullToMemberPointer: 5340 case CK_BaseToDerivedMemberPointer: 5341 case CK_DerivedToBaseMemberPointer: 5342 case CK_ReinterpretMemberPointer: 5343 case CK_ConstructorConversion: 5344 case CK_IntegralToPointer: 5345 case CK_ToVoid: 5346 case CK_VectorSplat: 5347 case CK_IntegralToFloating: 5348 case CK_FloatingCast: 5349 case CK_CPointerToObjCPointerCast: 5350 case CK_BlockPointerToObjCPointerCast: 5351 case CK_AnyPointerToBlockPointerCast: 5352 case CK_ObjCObjectLValueCast: 5353 case CK_FloatingRealToComplex: 5354 case CK_FloatingComplexToReal: 5355 case CK_FloatingComplexCast: 5356 case CK_FloatingComplexToIntegralComplex: 5357 case CK_IntegralRealToComplex: 5358 case CK_IntegralComplexCast: 5359 case CK_IntegralComplexToFloatingComplex: 5360 case CK_BuiltinFnToFnPtr: 5361 llvm_unreachable("invalid cast kind for integral value"); 5362 5363 case CK_BitCast: 5364 case CK_Dependent: 5365 case CK_LValueBitCast: 5366 case CK_ARCProduceObject: 5367 case CK_ARCConsumeObject: 5368 case CK_ARCReclaimReturnedObject: 5369 case CK_ARCExtendBlockObject: 5370 case CK_CopyAndAutoreleaseBlockObject: 5371 return Error(E); 5372 5373 case CK_UserDefinedConversion: 5374 case CK_LValueToRValue: 5375 case CK_AtomicToNonAtomic: 5376 case CK_NonAtomicToAtomic: 5377 case CK_NoOp: 5378 return ExprEvaluatorBaseTy::VisitCastExpr(E); 5379 5380 case CK_MemberPointerToBoolean: 5381 case CK_PointerToBoolean: 5382 case CK_IntegralToBoolean: 5383 case CK_FloatingToBoolean: 5384 case CK_FloatingComplexToBoolean: 5385 case CK_IntegralComplexToBoolean: { 5386 bool BoolResult; 5387 if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info)) 5388 return false; 5389 return Success(BoolResult, E); 5390 } 5391 5392 case CK_IntegralCast: { 5393 if (!Visit(SubExpr)) 5394 return false; 5395 5396 if (!Result.isInt()) { 5397 // Allow casts of address-of-label differences if they are no-ops 5398 // or narrowing. (The narrowing case isn't actually guaranteed to 5399 // be constant-evaluatable except in some narrow cases which are hard 5400 // to detect here. We let it through on the assumption the user knows 5401 // what they are doing.) 5402 if (Result.isAddrLabelDiff()) 5403 return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType); 5404 // Only allow casts of lvalues if they are lossless. 5405 return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType); 5406 } 5407 5408 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, 5409 Result.getInt()), E); 5410 } 5411 5412 case CK_PointerToIntegral: { 5413 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 5414 5415 LValue LV; 5416 if (!EvaluatePointer(SubExpr, LV, Info)) 5417 return false; 5418 5419 if (LV.getLValueBase()) { 5420 // Only allow based lvalue casts if they are lossless. 5421 // FIXME: Allow a larger integer size than the pointer size, and allow 5422 // narrowing back down to pointer width in subsequent integral casts. 5423 // FIXME: Check integer type's active bits, not its type size. 5424 if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType)) 5425 return Error(E); 5426 5427 LV.Designator.setInvalid(); 5428 LV.moveInto(Result); 5429 return true; 5430 } 5431 5432 APSInt AsInt = Info.Ctx.MakeIntValue(LV.getLValueOffset().getQuantity(), 5433 SrcType); 5434 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E); 5435 } 5436 5437 case CK_IntegralComplexToReal: { 5438 ComplexValue C; 5439 if (!EvaluateComplex(SubExpr, C, Info)) 5440 return false; 5441 return Success(C.getComplexIntReal(), E); 5442 } 5443 5444 case CK_FloatingToIntegral: { 5445 APFloat F(0.0); 5446 if (!EvaluateFloat(SubExpr, F, Info)) 5447 return false; 5448 5449 APSInt Value; 5450 if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value)) 5451 return false; 5452 return Success(Value, E); 5453 } 5454 } 5455 5456 llvm_unreachable("unknown cast resulting in integral value"); 5457 } 5458 5459 bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 5460 if (E->getSubExpr()->getType()->isAnyComplexType()) { 5461 ComplexValue LV; 5462 if (!EvaluateComplex(E->getSubExpr(), LV, Info)) 5463 return false; 5464 if (!LV.isComplexInt()) 5465 return Error(E); 5466 return Success(LV.getComplexIntReal(), E); 5467 } 5468 5469 return Visit(E->getSubExpr()); 5470 } 5471 5472 bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 5473 if (E->getSubExpr()->getType()->isComplexIntegerType()) { 5474 ComplexValue LV; 5475 if (!EvaluateComplex(E->getSubExpr(), LV, Info)) 5476 return false; 5477 if (!LV.isComplexInt()) 5478 return Error(E); 5479 return Success(LV.getComplexIntImag(), E); 5480 } 5481 5482 VisitIgnoredValue(E->getSubExpr()); 5483 return Success(0, E); 5484 } 5485 5486 bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) { 5487 return Success(E->getPackLength(), E); 5488 } 5489 5490 bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) { 5491 return Success(E->getValue(), E); 5492 } 5493 5494 //===----------------------------------------------------------------------===// 5495 // Float Evaluation 5496 //===----------------------------------------------------------------------===// 5497 5498 namespace { 5499 class FloatExprEvaluator 5500 : public ExprEvaluatorBase<FloatExprEvaluator, bool> { 5501 APFloat &Result; 5502 public: 5503 FloatExprEvaluator(EvalInfo &info, APFloat &result) 5504 : ExprEvaluatorBaseTy(info), Result(result) {} 5505 5506 bool Success(const APValue &V, const Expr *e) { 5507 Result = V.getFloat(); 5508 return true; 5509 } 5510 5511 bool ZeroInitialization(const Expr *E) { 5512 Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType())); 5513 return true; 5514 } 5515 5516 bool VisitCallExpr(const CallExpr *E); 5517 5518 bool VisitUnaryOperator(const UnaryOperator *E); 5519 bool VisitBinaryOperator(const BinaryOperator *E); 5520 bool VisitFloatingLiteral(const FloatingLiteral *E); 5521 bool VisitCastExpr(const CastExpr *E); 5522 5523 bool VisitUnaryReal(const UnaryOperator *E); 5524 bool VisitUnaryImag(const UnaryOperator *E); 5525 5526 // FIXME: Missing: array subscript of vector, member of vector 5527 }; 5528 } // end anonymous namespace 5529 5530 static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) { 5531 assert(E->isRValue() && E->getType()->isRealFloatingType()); 5532 return FloatExprEvaluator(Info, Result).Visit(E); 5533 } 5534 5535 static bool TryEvaluateBuiltinNaN(const ASTContext &Context, 5536 QualType ResultTy, 5537 const Expr *Arg, 5538 bool SNaN, 5539 llvm::APFloat &Result) { 5540 const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts()); 5541 if (!S) return false; 5542 5543 const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy); 5544 5545 llvm::APInt fill; 5546 5547 // Treat empty strings as if they were zero. 5548 if (S->getString().empty()) 5549 fill = llvm::APInt(32, 0); 5550 else if (S->getString().getAsInteger(0, fill)) 5551 return false; 5552 5553 if (SNaN) 5554 Result = llvm::APFloat::getSNaN(Sem, false, &fill); 5555 else 5556 Result = llvm::APFloat::getQNaN(Sem, false, &fill); 5557 return true; 5558 } 5559 5560 bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) { 5561 switch (E->isBuiltinCall()) { 5562 default: 5563 return ExprEvaluatorBaseTy::VisitCallExpr(E); 5564 5565 case Builtin::BI__builtin_huge_val: 5566 case Builtin::BI__builtin_huge_valf: 5567 case Builtin::BI__builtin_huge_vall: 5568 case Builtin::BI__builtin_inf: 5569 case Builtin::BI__builtin_inff: 5570 case Builtin::BI__builtin_infl: { 5571 const llvm::fltSemantics &Sem = 5572 Info.Ctx.getFloatTypeSemantics(E->getType()); 5573 Result = llvm::APFloat::getInf(Sem); 5574 return true; 5575 } 5576 5577 case Builtin::BI__builtin_nans: 5578 case Builtin::BI__builtin_nansf: 5579 case Builtin::BI__builtin_nansl: 5580 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), 5581 true, Result)) 5582 return Error(E); 5583 return true; 5584 5585 case Builtin::BI__builtin_nan: 5586 case Builtin::BI__builtin_nanf: 5587 case Builtin::BI__builtin_nanl: 5588 // If this is __builtin_nan() turn this into a nan, otherwise we 5589 // can't constant fold it. 5590 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), 5591 false, Result)) 5592 return Error(E); 5593 return true; 5594 5595 case Builtin::BI__builtin_fabs: 5596 case Builtin::BI__builtin_fabsf: 5597 case Builtin::BI__builtin_fabsl: 5598 if (!EvaluateFloat(E->getArg(0), Result, Info)) 5599 return false; 5600 5601 if (Result.isNegative()) 5602 Result.changeSign(); 5603 return true; 5604 5605 case Builtin::BI__builtin_copysign: 5606 case Builtin::BI__builtin_copysignf: 5607 case Builtin::BI__builtin_copysignl: { 5608 APFloat RHS(0.); 5609 if (!EvaluateFloat(E->getArg(0), Result, Info) || 5610 !EvaluateFloat(E->getArg(1), RHS, Info)) 5611 return false; 5612 Result.copySign(RHS); 5613 return true; 5614 } 5615 } 5616 } 5617 5618 bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 5619 if (E->getSubExpr()->getType()->isAnyComplexType()) { 5620 ComplexValue CV; 5621 if (!EvaluateComplex(E->getSubExpr(), CV, Info)) 5622 return false; 5623 Result = CV.FloatReal; 5624 return true; 5625 } 5626 5627 return Visit(E->getSubExpr()); 5628 } 5629 5630 bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 5631 if (E->getSubExpr()->getType()->isAnyComplexType()) { 5632 ComplexValue CV; 5633 if (!EvaluateComplex(E->getSubExpr(), CV, Info)) 5634 return false; 5635 Result = CV.FloatImag; 5636 return true; 5637 } 5638 5639 VisitIgnoredValue(E->getSubExpr()); 5640 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType()); 5641 Result = llvm::APFloat::getZero(Sem); 5642 return true; 5643 } 5644 5645 bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 5646 switch (E->getOpcode()) { 5647 default: return Error(E); 5648 case UO_Plus: 5649 return EvaluateFloat(E->getSubExpr(), Result, Info); 5650 case UO_Minus: 5651 if (!EvaluateFloat(E->getSubExpr(), Result, Info)) 5652 return false; 5653 Result.changeSign(); 5654 return true; 5655 } 5656 } 5657 5658 bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 5659 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) 5660 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 5661 5662 APFloat RHS(0.0); 5663 bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info); 5664 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 5665 return false; 5666 if (!EvaluateFloat(E->getRHS(), RHS, Info) || !LHSOK) 5667 return false; 5668 5669 switch (E->getOpcode()) { 5670 default: return Error(E); 5671 case BO_Mul: 5672 Result.multiply(RHS, APFloat::rmNearestTiesToEven); 5673 break; 5674 case BO_Add: 5675 Result.add(RHS, APFloat::rmNearestTiesToEven); 5676 break; 5677 case BO_Sub: 5678 Result.subtract(RHS, APFloat::rmNearestTiesToEven); 5679 break; 5680 case BO_Div: 5681 Result.divide(RHS, APFloat::rmNearestTiesToEven); 5682 break; 5683 } 5684 5685 if (Result.isInfinity() || Result.isNaN()) 5686 CCEDiag(E, diag::note_constexpr_float_arithmetic) << Result.isNaN(); 5687 return true; 5688 } 5689 5690 bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) { 5691 Result = E->getValue(); 5692 return true; 5693 } 5694 5695 bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) { 5696 const Expr* SubExpr = E->getSubExpr(); 5697 5698 switch (E->getCastKind()) { 5699 default: 5700 return ExprEvaluatorBaseTy::VisitCastExpr(E); 5701 5702 case CK_IntegralToFloating: { 5703 APSInt IntResult; 5704 return EvaluateInteger(SubExpr, IntResult, Info) && 5705 HandleIntToFloatCast(Info, E, SubExpr->getType(), IntResult, 5706 E->getType(), Result); 5707 } 5708 5709 case CK_FloatingCast: { 5710 if (!Visit(SubExpr)) 5711 return false; 5712 return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(), 5713 Result); 5714 } 5715 5716 case CK_FloatingComplexToReal: { 5717 ComplexValue V; 5718 if (!EvaluateComplex(SubExpr, V, Info)) 5719 return false; 5720 Result = V.getComplexFloatReal(); 5721 return true; 5722 } 5723 } 5724 } 5725 5726 //===----------------------------------------------------------------------===// 5727 // Complex Evaluation (for float and integer) 5728 //===----------------------------------------------------------------------===// 5729 5730 namespace { 5731 class ComplexExprEvaluator 5732 : public ExprEvaluatorBase<ComplexExprEvaluator, bool> { 5733 ComplexValue &Result; 5734 5735 public: 5736 ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result) 5737 : ExprEvaluatorBaseTy(info), Result(Result) {} 5738 5739 bool Success(const APValue &V, const Expr *e) { 5740 Result.setFrom(V); 5741 return true; 5742 } 5743 5744 bool ZeroInitialization(const Expr *E); 5745 5746 //===--------------------------------------------------------------------===// 5747 // Visitor Methods 5748 //===--------------------------------------------------------------------===// 5749 5750 bool VisitImaginaryLiteral(const ImaginaryLiteral *E); 5751 bool VisitCastExpr(const CastExpr *E); 5752 bool VisitBinaryOperator(const BinaryOperator *E); 5753 bool VisitUnaryOperator(const UnaryOperator *E); 5754 bool VisitInitListExpr(const InitListExpr *E); 5755 }; 5756 } // end anonymous namespace 5757 5758 static bool EvaluateComplex(const Expr *E, ComplexValue &Result, 5759 EvalInfo &Info) { 5760 assert(E->isRValue() && E->getType()->isAnyComplexType()); 5761 return ComplexExprEvaluator(Info, Result).Visit(E); 5762 } 5763 5764 bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) { 5765 QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType(); 5766 if (ElemTy->isRealFloatingType()) { 5767 Result.makeComplexFloat(); 5768 APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy)); 5769 Result.FloatReal = Zero; 5770 Result.FloatImag = Zero; 5771 } else { 5772 Result.makeComplexInt(); 5773 APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy); 5774 Result.IntReal = Zero; 5775 Result.IntImag = Zero; 5776 } 5777 return true; 5778 } 5779 5780 bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) { 5781 const Expr* SubExpr = E->getSubExpr(); 5782 5783 if (SubExpr->getType()->isRealFloatingType()) { 5784 Result.makeComplexFloat(); 5785 APFloat &Imag = Result.FloatImag; 5786 if (!EvaluateFloat(SubExpr, Imag, Info)) 5787 return false; 5788 5789 Result.FloatReal = APFloat(Imag.getSemantics()); 5790 return true; 5791 } else { 5792 assert(SubExpr->getType()->isIntegerType() && 5793 "Unexpected imaginary literal."); 5794 5795 Result.makeComplexInt(); 5796 APSInt &Imag = Result.IntImag; 5797 if (!EvaluateInteger(SubExpr, Imag, Info)) 5798 return false; 5799 5800 Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned()); 5801 return true; 5802 } 5803 } 5804 5805 bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) { 5806 5807 switch (E->getCastKind()) { 5808 case CK_BitCast: 5809 case CK_BaseToDerived: 5810 case CK_DerivedToBase: 5811 case CK_UncheckedDerivedToBase: 5812 case CK_Dynamic: 5813 case CK_ToUnion: 5814 case CK_ArrayToPointerDecay: 5815 case CK_FunctionToPointerDecay: 5816 case CK_NullToPointer: 5817 case CK_NullToMemberPointer: 5818 case CK_BaseToDerivedMemberPointer: 5819 case CK_DerivedToBaseMemberPointer: 5820 case CK_MemberPointerToBoolean: 5821 case CK_ReinterpretMemberPointer: 5822 case CK_ConstructorConversion: 5823 case CK_IntegralToPointer: 5824 case CK_PointerToIntegral: 5825 case CK_PointerToBoolean: 5826 case CK_ToVoid: 5827 case CK_VectorSplat: 5828 case CK_IntegralCast: 5829 case CK_IntegralToBoolean: 5830 case CK_IntegralToFloating: 5831 case CK_FloatingToIntegral: 5832 case CK_FloatingToBoolean: 5833 case CK_FloatingCast: 5834 case CK_CPointerToObjCPointerCast: 5835 case CK_BlockPointerToObjCPointerCast: 5836 case CK_AnyPointerToBlockPointerCast: 5837 case CK_ObjCObjectLValueCast: 5838 case CK_FloatingComplexToReal: 5839 case CK_FloatingComplexToBoolean: 5840 case CK_IntegralComplexToReal: 5841 case CK_IntegralComplexToBoolean: 5842 case CK_ARCProduceObject: 5843 case CK_ARCConsumeObject: 5844 case CK_ARCReclaimReturnedObject: 5845 case CK_ARCExtendBlockObject: 5846 case CK_CopyAndAutoreleaseBlockObject: 5847 case CK_BuiltinFnToFnPtr: 5848 llvm_unreachable("invalid cast kind for complex value"); 5849 5850 case CK_LValueToRValue: 5851 case CK_AtomicToNonAtomic: 5852 case CK_NonAtomicToAtomic: 5853 case CK_NoOp: 5854 return ExprEvaluatorBaseTy::VisitCastExpr(E); 5855 5856 case CK_Dependent: 5857 case CK_LValueBitCast: 5858 case CK_UserDefinedConversion: 5859 return Error(E); 5860 5861 case CK_FloatingRealToComplex: { 5862 APFloat &Real = Result.FloatReal; 5863 if (!EvaluateFloat(E->getSubExpr(), Real, Info)) 5864 return false; 5865 5866 Result.makeComplexFloat(); 5867 Result.FloatImag = APFloat(Real.getSemantics()); 5868 return true; 5869 } 5870 5871 case CK_FloatingComplexCast: { 5872 if (!Visit(E->getSubExpr())) 5873 return false; 5874 5875 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 5876 QualType From 5877 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 5878 5879 return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) && 5880 HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag); 5881 } 5882 5883 case CK_FloatingComplexToIntegralComplex: { 5884 if (!Visit(E->getSubExpr())) 5885 return false; 5886 5887 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 5888 QualType From 5889 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 5890 Result.makeComplexInt(); 5891 return HandleFloatToIntCast(Info, E, From, Result.FloatReal, 5892 To, Result.IntReal) && 5893 HandleFloatToIntCast(Info, E, From, Result.FloatImag, 5894 To, Result.IntImag); 5895 } 5896 5897 case CK_IntegralRealToComplex: { 5898 APSInt &Real = Result.IntReal; 5899 if (!EvaluateInteger(E->getSubExpr(), Real, Info)) 5900 return false; 5901 5902 Result.makeComplexInt(); 5903 Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned()); 5904 return true; 5905 } 5906 5907 case CK_IntegralComplexCast: { 5908 if (!Visit(E->getSubExpr())) 5909 return false; 5910 5911 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 5912 QualType From 5913 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 5914 5915 Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal); 5916 Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag); 5917 return true; 5918 } 5919 5920 case CK_IntegralComplexToFloatingComplex: { 5921 if (!Visit(E->getSubExpr())) 5922 return false; 5923 5924 QualType To = E->getType()->castAs<ComplexType>()->getElementType(); 5925 QualType From 5926 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType(); 5927 Result.makeComplexFloat(); 5928 return HandleIntToFloatCast(Info, E, From, Result.IntReal, 5929 To, Result.FloatReal) && 5930 HandleIntToFloatCast(Info, E, From, Result.IntImag, 5931 To, Result.FloatImag); 5932 } 5933 } 5934 5935 llvm_unreachable("unknown cast resulting in complex value"); 5936 } 5937 5938 bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 5939 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) 5940 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 5941 5942 bool LHSOK = Visit(E->getLHS()); 5943 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 5944 return false; 5945 5946 ComplexValue RHS; 5947 if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) 5948 return false; 5949 5950 assert(Result.isComplexFloat() == RHS.isComplexFloat() && 5951 "Invalid operands to binary operator."); 5952 switch (E->getOpcode()) { 5953 default: return Error(E); 5954 case BO_Add: 5955 if (Result.isComplexFloat()) { 5956 Result.getComplexFloatReal().add(RHS.getComplexFloatReal(), 5957 APFloat::rmNearestTiesToEven); 5958 Result.getComplexFloatImag().add(RHS.getComplexFloatImag(), 5959 APFloat::rmNearestTiesToEven); 5960 } else { 5961 Result.getComplexIntReal() += RHS.getComplexIntReal(); 5962 Result.getComplexIntImag() += RHS.getComplexIntImag(); 5963 } 5964 break; 5965 case BO_Sub: 5966 if (Result.isComplexFloat()) { 5967 Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(), 5968 APFloat::rmNearestTiesToEven); 5969 Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(), 5970 APFloat::rmNearestTiesToEven); 5971 } else { 5972 Result.getComplexIntReal() -= RHS.getComplexIntReal(); 5973 Result.getComplexIntImag() -= RHS.getComplexIntImag(); 5974 } 5975 break; 5976 case BO_Mul: 5977 if (Result.isComplexFloat()) { 5978 ComplexValue LHS = Result; 5979 APFloat &LHS_r = LHS.getComplexFloatReal(); 5980 APFloat &LHS_i = LHS.getComplexFloatImag(); 5981 APFloat &RHS_r = RHS.getComplexFloatReal(); 5982 APFloat &RHS_i = RHS.getComplexFloatImag(); 5983 5984 APFloat Tmp = LHS_r; 5985 Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven); 5986 Result.getComplexFloatReal() = Tmp; 5987 Tmp = LHS_i; 5988 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 5989 Result.getComplexFloatReal().subtract(Tmp, APFloat::rmNearestTiesToEven); 5990 5991 Tmp = LHS_r; 5992 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 5993 Result.getComplexFloatImag() = Tmp; 5994 Tmp = LHS_i; 5995 Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven); 5996 Result.getComplexFloatImag().add(Tmp, APFloat::rmNearestTiesToEven); 5997 } else { 5998 ComplexValue LHS = Result; 5999 Result.getComplexIntReal() = 6000 (LHS.getComplexIntReal() * RHS.getComplexIntReal() - 6001 LHS.getComplexIntImag() * RHS.getComplexIntImag()); 6002 Result.getComplexIntImag() = 6003 (LHS.getComplexIntReal() * RHS.getComplexIntImag() + 6004 LHS.getComplexIntImag() * RHS.getComplexIntReal()); 6005 } 6006 break; 6007 case BO_Div: 6008 if (Result.isComplexFloat()) { 6009 ComplexValue LHS = Result; 6010 APFloat &LHS_r = LHS.getComplexFloatReal(); 6011 APFloat &LHS_i = LHS.getComplexFloatImag(); 6012 APFloat &RHS_r = RHS.getComplexFloatReal(); 6013 APFloat &RHS_i = RHS.getComplexFloatImag(); 6014 APFloat &Res_r = Result.getComplexFloatReal(); 6015 APFloat &Res_i = Result.getComplexFloatImag(); 6016 6017 APFloat Den = RHS_r; 6018 Den.multiply(RHS_r, APFloat::rmNearestTiesToEven); 6019 APFloat Tmp = RHS_i; 6020 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 6021 Den.add(Tmp, APFloat::rmNearestTiesToEven); 6022 6023 Res_r = LHS_r; 6024 Res_r.multiply(RHS_r, APFloat::rmNearestTiesToEven); 6025 Tmp = LHS_i; 6026 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 6027 Res_r.add(Tmp, APFloat::rmNearestTiesToEven); 6028 Res_r.divide(Den, APFloat::rmNearestTiesToEven); 6029 6030 Res_i = LHS_i; 6031 Res_i.multiply(RHS_r, APFloat::rmNearestTiesToEven); 6032 Tmp = LHS_r; 6033 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 6034 Res_i.subtract(Tmp, APFloat::rmNearestTiesToEven); 6035 Res_i.divide(Den, APFloat::rmNearestTiesToEven); 6036 } else { 6037 if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0) 6038 return Error(E, diag::note_expr_divide_by_zero); 6039 6040 ComplexValue LHS = Result; 6041 APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() + 6042 RHS.getComplexIntImag() * RHS.getComplexIntImag(); 6043 Result.getComplexIntReal() = 6044 (LHS.getComplexIntReal() * RHS.getComplexIntReal() + 6045 LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den; 6046 Result.getComplexIntImag() = 6047 (LHS.getComplexIntImag() * RHS.getComplexIntReal() - 6048 LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den; 6049 } 6050 break; 6051 } 6052 6053 return true; 6054 } 6055 6056 bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 6057 // Get the operand value into 'Result'. 6058 if (!Visit(E->getSubExpr())) 6059 return false; 6060 6061 switch (E->getOpcode()) { 6062 default: 6063 return Error(E); 6064 case UO_Extension: 6065 return true; 6066 case UO_Plus: 6067 // The result is always just the subexpr. 6068 return true; 6069 case UO_Minus: 6070 if (Result.isComplexFloat()) { 6071 Result.getComplexFloatReal().changeSign(); 6072 Result.getComplexFloatImag().changeSign(); 6073 } 6074 else { 6075 Result.getComplexIntReal() = -Result.getComplexIntReal(); 6076 Result.getComplexIntImag() = -Result.getComplexIntImag(); 6077 } 6078 return true; 6079 case UO_Not: 6080 if (Result.isComplexFloat()) 6081 Result.getComplexFloatImag().changeSign(); 6082 else 6083 Result.getComplexIntImag() = -Result.getComplexIntImag(); 6084 return true; 6085 } 6086 } 6087 6088 bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 6089 if (E->getNumInits() == 2) { 6090 if (E->getType()->isComplexType()) { 6091 Result.makeComplexFloat(); 6092 if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info)) 6093 return false; 6094 if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info)) 6095 return false; 6096 } else { 6097 Result.makeComplexInt(); 6098 if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info)) 6099 return false; 6100 if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info)) 6101 return false; 6102 } 6103 return true; 6104 } 6105 return ExprEvaluatorBaseTy::VisitInitListExpr(E); 6106 } 6107 6108 //===----------------------------------------------------------------------===// 6109 // Void expression evaluation, primarily for a cast to void on the LHS of a 6110 // comma operator 6111 //===----------------------------------------------------------------------===// 6112 6113 namespace { 6114 class VoidExprEvaluator 6115 : public ExprEvaluatorBase<VoidExprEvaluator, bool> { 6116 public: 6117 VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {} 6118 6119 bool Success(const APValue &V, const Expr *e) { return true; } 6120 6121 bool VisitCastExpr(const CastExpr *E) { 6122 switch (E->getCastKind()) { 6123 default: 6124 return ExprEvaluatorBaseTy::VisitCastExpr(E); 6125 case CK_ToVoid: 6126 VisitIgnoredValue(E->getSubExpr()); 6127 return true; 6128 } 6129 } 6130 }; 6131 } // end anonymous namespace 6132 6133 static bool EvaluateVoid(const Expr *E, EvalInfo &Info) { 6134 assert(E->isRValue() && E->getType()->isVoidType()); 6135 return VoidExprEvaluator(Info).Visit(E); 6136 } 6137 6138 //===----------------------------------------------------------------------===// 6139 // Top level Expr::EvaluateAsRValue method. 6140 //===----------------------------------------------------------------------===// 6141 6142 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) { 6143 // In C, function designators are not lvalues, but we evaluate them as if they 6144 // are. 6145 if (E->isGLValue() || E->getType()->isFunctionType()) { 6146 LValue LV; 6147 if (!EvaluateLValue(E, LV, Info)) 6148 return false; 6149 LV.moveInto(Result); 6150 } else if (E->getType()->isVectorType()) { 6151 if (!EvaluateVector(E, Result, Info)) 6152 return false; 6153 } else if (E->getType()->isIntegralOrEnumerationType()) { 6154 if (!IntExprEvaluator(Info, Result).Visit(E)) 6155 return false; 6156 } else if (E->getType()->hasPointerRepresentation()) { 6157 LValue LV; 6158 if (!EvaluatePointer(E, LV, Info)) 6159 return false; 6160 LV.moveInto(Result); 6161 } else if (E->getType()->isRealFloatingType()) { 6162 llvm::APFloat F(0.0); 6163 if (!EvaluateFloat(E, F, Info)) 6164 return false; 6165 Result = APValue(F); 6166 } else if (E->getType()->isAnyComplexType()) { 6167 ComplexValue C; 6168 if (!EvaluateComplex(E, C, Info)) 6169 return false; 6170 C.moveInto(Result); 6171 } else if (E->getType()->isMemberPointerType()) { 6172 MemberPtr P; 6173 if (!EvaluateMemberPointer(E, P, Info)) 6174 return false; 6175 P.moveInto(Result); 6176 return true; 6177 } else if (E->getType()->isArrayType()) { 6178 LValue LV; 6179 LV.set(E, Info.CurrentCall->Index); 6180 if (!EvaluateArray(E, LV, Info.CurrentCall->Temporaries[E], Info)) 6181 return false; 6182 Result = Info.CurrentCall->Temporaries[E]; 6183 } else if (E->getType()->isRecordType()) { 6184 LValue LV; 6185 LV.set(E, Info.CurrentCall->Index); 6186 if (!EvaluateRecord(E, LV, Info.CurrentCall->Temporaries[E], Info)) 6187 return false; 6188 Result = Info.CurrentCall->Temporaries[E]; 6189 } else if (E->getType()->isVoidType()) { 6190 if (Info.getLangOpts().CPlusPlus0x) 6191 Info.CCEDiag(E, diag::note_constexpr_nonliteral) 6192 << E->getType(); 6193 else 6194 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 6195 if (!EvaluateVoid(E, Info)) 6196 return false; 6197 } else if (Info.getLangOpts().CPlusPlus0x) { 6198 Info.Diag(E, diag::note_constexpr_nonliteral) << E->getType(); 6199 return false; 6200 } else { 6201 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 6202 return false; 6203 } 6204 6205 return true; 6206 } 6207 6208 /// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some 6209 /// cases, the in-place evaluation is essential, since later initializers for 6210 /// an object can indirectly refer to subobjects which were initialized earlier. 6211 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This, 6212 const Expr *E, CheckConstantExpressionKind CCEK, 6213 bool AllowNonLiteralTypes) { 6214 if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E)) 6215 return false; 6216 6217 if (E->isRValue()) { 6218 // Evaluate arrays and record types in-place, so that later initializers can 6219 // refer to earlier-initialized members of the object. 6220 if (E->getType()->isArrayType()) 6221 return EvaluateArray(E, This, Result, Info); 6222 else if (E->getType()->isRecordType()) 6223 return EvaluateRecord(E, This, Result, Info); 6224 } 6225 6226 // For any other type, in-place evaluation is unimportant. 6227 return Evaluate(Result, Info, E); 6228 } 6229 6230 /// EvaluateAsRValue - Try to evaluate this expression, performing an implicit 6231 /// lvalue-to-rvalue cast if it is an lvalue. 6232 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) { 6233 if (!CheckLiteralType(Info, E)) 6234 return false; 6235 6236 if (!::Evaluate(Result, Info, E)) 6237 return false; 6238 6239 if (E->isGLValue()) { 6240 LValue LV; 6241 LV.setFrom(Info.Ctx, Result); 6242 if (!HandleLValueToRValueConversion(Info, E, E->getType(), LV, Result)) 6243 return false; 6244 } 6245 6246 // Check this core constant expression is a constant expression. 6247 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result); 6248 } 6249 6250 /// EvaluateAsRValue - Return true if this is a constant which we can fold using 6251 /// any crazy technique (that has nothing to do with language standards) that 6252 /// we want to. If this function returns true, it returns the folded constant 6253 /// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion 6254 /// will be applied to the result. 6255 bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx) const { 6256 // Fast-path evaluations of integer literals, since we sometimes see files 6257 // containing vast quantities of these. 6258 if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(this)) { 6259 Result.Val = APValue(APSInt(L->getValue(), 6260 L->getType()->isUnsignedIntegerType())); 6261 return true; 6262 } 6263 6264 // FIXME: Evaluating values of large array and record types can cause 6265 // performance problems. Only do so in C++11 for now. 6266 if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) && 6267 !Ctx.getLangOpts().CPlusPlus0x) 6268 return false; 6269 6270 EvalInfo Info(Ctx, Result); 6271 return ::EvaluateAsRValue(Info, this, Result.Val); 6272 } 6273 6274 bool Expr::EvaluateAsBooleanCondition(bool &Result, 6275 const ASTContext &Ctx) const { 6276 EvalResult Scratch; 6277 return EvaluateAsRValue(Scratch, Ctx) && 6278 HandleConversionToBool(Scratch.Val, Result); 6279 } 6280 6281 bool Expr::EvaluateAsInt(APSInt &Result, const ASTContext &Ctx, 6282 SideEffectsKind AllowSideEffects) const { 6283 if (!getType()->isIntegralOrEnumerationType()) 6284 return false; 6285 6286 EvalResult ExprResult; 6287 if (!EvaluateAsRValue(ExprResult, Ctx) || !ExprResult.Val.isInt() || 6288 (!AllowSideEffects && ExprResult.HasSideEffects)) 6289 return false; 6290 6291 Result = ExprResult.Val.getInt(); 6292 return true; 6293 } 6294 6295 bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx) const { 6296 EvalInfo Info(Ctx, Result); 6297 6298 LValue LV; 6299 if (!EvaluateLValue(this, LV, Info) || Result.HasSideEffects || 6300 !CheckLValueConstantExpression(Info, getExprLoc(), 6301 Ctx.getLValueReferenceType(getType()), LV)) 6302 return false; 6303 6304 LV.moveInto(Result.Val); 6305 return true; 6306 } 6307 6308 bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx, 6309 const VarDecl *VD, 6310 llvm::SmallVectorImpl<PartialDiagnosticAt> &Notes) const { 6311 // FIXME: Evaluating initializers for large array and record types can cause 6312 // performance problems. Only do so in C++11 for now. 6313 if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) && 6314 !Ctx.getLangOpts().CPlusPlus0x) 6315 return false; 6316 6317 Expr::EvalStatus EStatus; 6318 EStatus.Diag = &Notes; 6319 6320 EvalInfo InitInfo(Ctx, EStatus); 6321 InitInfo.setEvaluatingDecl(VD, Value); 6322 6323 LValue LVal; 6324 LVal.set(VD); 6325 6326 // C++11 [basic.start.init]p2: 6327 // Variables with static storage duration or thread storage duration shall be 6328 // zero-initialized before any other initialization takes place. 6329 // This behavior is not present in C. 6330 if (Ctx.getLangOpts().CPlusPlus && !VD->hasLocalStorage() && 6331 !VD->getType()->isReferenceType()) { 6332 ImplicitValueInitExpr VIE(VD->getType()); 6333 if (!EvaluateInPlace(Value, InitInfo, LVal, &VIE, CCEK_Constant, 6334 /*AllowNonLiteralTypes=*/true)) 6335 return false; 6336 } 6337 6338 if (!EvaluateInPlace(Value, InitInfo, LVal, this, CCEK_Constant, 6339 /*AllowNonLiteralTypes=*/true) || 6340 EStatus.HasSideEffects) 6341 return false; 6342 6343 return CheckConstantExpression(InitInfo, VD->getLocation(), VD->getType(), 6344 Value); 6345 } 6346 6347 /// isEvaluatable - Call EvaluateAsRValue to see if this expression can be 6348 /// constant folded, but discard the result. 6349 bool Expr::isEvaluatable(const ASTContext &Ctx) const { 6350 EvalResult Result; 6351 return EvaluateAsRValue(Result, Ctx) && !Result.HasSideEffects; 6352 } 6353 6354 APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx) const { 6355 EvalResult EvalResult; 6356 bool Result = EvaluateAsRValue(EvalResult, Ctx); 6357 (void)Result; 6358 assert(Result && "Could not evaluate expression"); 6359 assert(EvalResult.Val.isInt() && "Expression did not evaluate to integer"); 6360 6361 return EvalResult.Val.getInt(); 6362 } 6363 6364 bool Expr::EvalResult::isGlobalLValue() const { 6365 assert(Val.isLValue()); 6366 return IsGlobalLValue(Val.getLValueBase()); 6367 } 6368 6369 6370 /// isIntegerConstantExpr - this recursive routine will test if an expression is 6371 /// an integer constant expression. 6372 6373 /// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero, 6374 /// comma, etc 6375 /// 6376 /// FIXME: Handle offsetof. Two things to do: Handle GCC's __builtin_offsetof 6377 /// to support gcc 4.0+ and handle the idiom GCC recognizes with a null pointer 6378 /// cast+dereference. 6379 6380 // CheckICE - This function does the fundamental ICE checking: the returned 6381 // ICEDiag contains a Val of 0, 1, or 2, and a possibly null SourceLocation. 6382 // Note that to reduce code duplication, this helper does no evaluation 6383 // itself; the caller checks whether the expression is evaluatable, and 6384 // in the rare cases where CheckICE actually cares about the evaluated 6385 // value, it calls into Evalute. 6386 // 6387 // Meanings of Val: 6388 // 0: This expression is an ICE. 6389 // 1: This expression is not an ICE, but if it isn't evaluated, it's 6390 // a legal subexpression for an ICE. This return value is used to handle 6391 // the comma operator in C99 mode. 6392 // 2: This expression is not an ICE, and is not a legal subexpression for one. 6393 6394 namespace { 6395 6396 struct ICEDiag { 6397 unsigned Val; 6398 SourceLocation Loc; 6399 6400 public: 6401 ICEDiag(unsigned v, SourceLocation l) : Val(v), Loc(l) {} 6402 ICEDiag() : Val(0) {} 6403 }; 6404 6405 } 6406 6407 static ICEDiag NoDiag() { return ICEDiag(); } 6408 6409 static ICEDiag CheckEvalInICE(const Expr* E, ASTContext &Ctx) { 6410 Expr::EvalResult EVResult; 6411 if (!E->EvaluateAsRValue(EVResult, Ctx) || EVResult.HasSideEffects || 6412 !EVResult.Val.isInt()) { 6413 return ICEDiag(2, E->getLocStart()); 6414 } 6415 return NoDiag(); 6416 } 6417 6418 static ICEDiag CheckICE(const Expr* E, ASTContext &Ctx) { 6419 assert(!E->isValueDependent() && "Should not see value dependent exprs!"); 6420 if (!E->getType()->isIntegralOrEnumerationType()) { 6421 return ICEDiag(2, E->getLocStart()); 6422 } 6423 6424 switch (E->getStmtClass()) { 6425 #define ABSTRACT_STMT(Node) 6426 #define STMT(Node, Base) case Expr::Node##Class: 6427 #define EXPR(Node, Base) 6428 #include "clang/AST/StmtNodes.inc" 6429 case Expr::PredefinedExprClass: 6430 case Expr::FloatingLiteralClass: 6431 case Expr::ImaginaryLiteralClass: 6432 case Expr::StringLiteralClass: 6433 case Expr::ArraySubscriptExprClass: 6434 case Expr::MemberExprClass: 6435 case Expr::CompoundAssignOperatorClass: 6436 case Expr::CompoundLiteralExprClass: 6437 case Expr::ExtVectorElementExprClass: 6438 case Expr::DesignatedInitExprClass: 6439 case Expr::ImplicitValueInitExprClass: 6440 case Expr::ParenListExprClass: 6441 case Expr::VAArgExprClass: 6442 case Expr::AddrLabelExprClass: 6443 case Expr::StmtExprClass: 6444 case Expr::CXXMemberCallExprClass: 6445 case Expr::CUDAKernelCallExprClass: 6446 case Expr::CXXDynamicCastExprClass: 6447 case Expr::CXXTypeidExprClass: 6448 case Expr::CXXUuidofExprClass: 6449 case Expr::CXXNullPtrLiteralExprClass: 6450 case Expr::UserDefinedLiteralClass: 6451 case Expr::CXXThisExprClass: 6452 case Expr::CXXThrowExprClass: 6453 case Expr::CXXNewExprClass: 6454 case Expr::CXXDeleteExprClass: 6455 case Expr::CXXPseudoDestructorExprClass: 6456 case Expr::UnresolvedLookupExprClass: 6457 case Expr::DependentScopeDeclRefExprClass: 6458 case Expr::CXXConstructExprClass: 6459 case Expr::CXXBindTemporaryExprClass: 6460 case Expr::ExprWithCleanupsClass: 6461 case Expr::CXXTemporaryObjectExprClass: 6462 case Expr::CXXUnresolvedConstructExprClass: 6463 case Expr::CXXDependentScopeMemberExprClass: 6464 case Expr::UnresolvedMemberExprClass: 6465 case Expr::ObjCStringLiteralClass: 6466 case Expr::ObjCBoxedExprClass: 6467 case Expr::ObjCArrayLiteralClass: 6468 case Expr::ObjCDictionaryLiteralClass: 6469 case Expr::ObjCEncodeExprClass: 6470 case Expr::ObjCMessageExprClass: 6471 case Expr::ObjCSelectorExprClass: 6472 case Expr::ObjCProtocolExprClass: 6473 case Expr::ObjCIvarRefExprClass: 6474 case Expr::ObjCPropertyRefExprClass: 6475 case Expr::ObjCSubscriptRefExprClass: 6476 case Expr::ObjCIsaExprClass: 6477 case Expr::ShuffleVectorExprClass: 6478 case Expr::BlockExprClass: 6479 case Expr::NoStmtClass: 6480 case Expr::OpaqueValueExprClass: 6481 case Expr::PackExpansionExprClass: 6482 case Expr::SubstNonTypeTemplateParmPackExprClass: 6483 case Expr::AsTypeExprClass: 6484 case Expr::ObjCIndirectCopyRestoreExprClass: 6485 case Expr::MaterializeTemporaryExprClass: 6486 case Expr::PseudoObjectExprClass: 6487 case Expr::AtomicExprClass: 6488 case Expr::InitListExprClass: 6489 case Expr::LambdaExprClass: 6490 return ICEDiag(2, E->getLocStart()); 6491 6492 case Expr::SizeOfPackExprClass: 6493 case Expr::GNUNullExprClass: 6494 // GCC considers the GNU __null value to be an integral constant expression. 6495 return NoDiag(); 6496 6497 case Expr::SubstNonTypeTemplateParmExprClass: 6498 return 6499 CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx); 6500 6501 case Expr::ParenExprClass: 6502 return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx); 6503 case Expr::GenericSelectionExprClass: 6504 return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx); 6505 case Expr::IntegerLiteralClass: 6506 case Expr::CharacterLiteralClass: 6507 case Expr::ObjCBoolLiteralExprClass: 6508 case Expr::CXXBoolLiteralExprClass: 6509 case Expr::CXXScalarValueInitExprClass: 6510 case Expr::UnaryTypeTraitExprClass: 6511 case Expr::BinaryTypeTraitExprClass: 6512 case Expr::TypeTraitExprClass: 6513 case Expr::ArrayTypeTraitExprClass: 6514 case Expr::ExpressionTraitExprClass: 6515 case Expr::CXXNoexceptExprClass: 6516 return NoDiag(); 6517 case Expr::CallExprClass: 6518 case Expr::CXXOperatorCallExprClass: { 6519 // C99 6.6/3 allows function calls within unevaluated subexpressions of 6520 // constant expressions, but they can never be ICEs because an ICE cannot 6521 // contain an operand of (pointer to) function type. 6522 const CallExpr *CE = cast<CallExpr>(E); 6523 if (CE->isBuiltinCall()) 6524 return CheckEvalInICE(E, Ctx); 6525 return ICEDiag(2, E->getLocStart()); 6526 } 6527 case Expr::DeclRefExprClass: { 6528 if (isa<EnumConstantDecl>(cast<DeclRefExpr>(E)->getDecl())) 6529 return NoDiag(); 6530 const ValueDecl *D = dyn_cast<ValueDecl>(cast<DeclRefExpr>(E)->getDecl()); 6531 if (Ctx.getLangOpts().CPlusPlus && 6532 D && IsConstNonVolatile(D->getType())) { 6533 // Parameter variables are never constants. Without this check, 6534 // getAnyInitializer() can find a default argument, which leads 6535 // to chaos. 6536 if (isa<ParmVarDecl>(D)) 6537 return ICEDiag(2, cast<DeclRefExpr>(E)->getLocation()); 6538 6539 // C++ 7.1.5.1p2 6540 // A variable of non-volatile const-qualified integral or enumeration 6541 // type initialized by an ICE can be used in ICEs. 6542 if (const VarDecl *Dcl = dyn_cast<VarDecl>(D)) { 6543 if (!Dcl->getType()->isIntegralOrEnumerationType()) 6544 return ICEDiag(2, cast<DeclRefExpr>(E)->getLocation()); 6545 6546 const VarDecl *VD; 6547 // Look for a declaration of this variable that has an initializer, and 6548 // check whether it is an ICE. 6549 if (Dcl->getAnyInitializer(VD) && VD->checkInitIsICE()) 6550 return NoDiag(); 6551 else 6552 return ICEDiag(2, cast<DeclRefExpr>(E)->getLocation()); 6553 } 6554 } 6555 return ICEDiag(2, E->getLocStart()); 6556 } 6557 case Expr::UnaryOperatorClass: { 6558 const UnaryOperator *Exp = cast<UnaryOperator>(E); 6559 switch (Exp->getOpcode()) { 6560 case UO_PostInc: 6561 case UO_PostDec: 6562 case UO_PreInc: 6563 case UO_PreDec: 6564 case UO_AddrOf: 6565 case UO_Deref: 6566 // C99 6.6/3 allows increment and decrement within unevaluated 6567 // subexpressions of constant expressions, but they can never be ICEs 6568 // because an ICE cannot contain an lvalue operand. 6569 return ICEDiag(2, E->getLocStart()); 6570 case UO_Extension: 6571 case UO_LNot: 6572 case UO_Plus: 6573 case UO_Minus: 6574 case UO_Not: 6575 case UO_Real: 6576 case UO_Imag: 6577 return CheckICE(Exp->getSubExpr(), Ctx); 6578 } 6579 6580 // OffsetOf falls through here. 6581 } 6582 case Expr::OffsetOfExprClass: { 6583 // Note that per C99, offsetof must be an ICE. And AFAIK, using 6584 // EvaluateAsRValue matches the proposed gcc behavior for cases like 6585 // "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect 6586 // compliance: we should warn earlier for offsetof expressions with 6587 // array subscripts that aren't ICEs, and if the array subscripts 6588 // are ICEs, the value of the offsetof must be an integer constant. 6589 return CheckEvalInICE(E, Ctx); 6590 } 6591 case Expr::UnaryExprOrTypeTraitExprClass: { 6592 const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E); 6593 if ((Exp->getKind() == UETT_SizeOf) && 6594 Exp->getTypeOfArgument()->isVariableArrayType()) 6595 return ICEDiag(2, E->getLocStart()); 6596 return NoDiag(); 6597 } 6598 case Expr::BinaryOperatorClass: { 6599 const BinaryOperator *Exp = cast<BinaryOperator>(E); 6600 switch (Exp->getOpcode()) { 6601 case BO_PtrMemD: 6602 case BO_PtrMemI: 6603 case BO_Assign: 6604 case BO_MulAssign: 6605 case BO_DivAssign: 6606 case BO_RemAssign: 6607 case BO_AddAssign: 6608 case BO_SubAssign: 6609 case BO_ShlAssign: 6610 case BO_ShrAssign: 6611 case BO_AndAssign: 6612 case BO_XorAssign: 6613 case BO_OrAssign: 6614 // C99 6.6/3 allows assignments within unevaluated subexpressions of 6615 // constant expressions, but they can never be ICEs because an ICE cannot 6616 // contain an lvalue operand. 6617 return ICEDiag(2, E->getLocStart()); 6618 6619 case BO_Mul: 6620 case BO_Div: 6621 case BO_Rem: 6622 case BO_Add: 6623 case BO_Sub: 6624 case BO_Shl: 6625 case BO_Shr: 6626 case BO_LT: 6627 case BO_GT: 6628 case BO_LE: 6629 case BO_GE: 6630 case BO_EQ: 6631 case BO_NE: 6632 case BO_And: 6633 case BO_Xor: 6634 case BO_Or: 6635 case BO_Comma: { 6636 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); 6637 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); 6638 if (Exp->getOpcode() == BO_Div || 6639 Exp->getOpcode() == BO_Rem) { 6640 // EvaluateAsRValue gives an error for undefined Div/Rem, so make sure 6641 // we don't evaluate one. 6642 if (LHSResult.Val == 0 && RHSResult.Val == 0) { 6643 llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx); 6644 if (REval == 0) 6645 return ICEDiag(1, E->getLocStart()); 6646 if (REval.isSigned() && REval.isAllOnesValue()) { 6647 llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx); 6648 if (LEval.isMinSignedValue()) 6649 return ICEDiag(1, E->getLocStart()); 6650 } 6651 } 6652 } 6653 if (Exp->getOpcode() == BO_Comma) { 6654 if (Ctx.getLangOpts().C99) { 6655 // C99 6.6p3 introduces a strange edge case: comma can be in an ICE 6656 // if it isn't evaluated. 6657 if (LHSResult.Val == 0 && RHSResult.Val == 0) 6658 return ICEDiag(1, E->getLocStart()); 6659 } else { 6660 // In both C89 and C++, commas in ICEs are illegal. 6661 return ICEDiag(2, E->getLocStart()); 6662 } 6663 } 6664 if (LHSResult.Val >= RHSResult.Val) 6665 return LHSResult; 6666 return RHSResult; 6667 } 6668 case BO_LAnd: 6669 case BO_LOr: { 6670 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); 6671 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); 6672 if (LHSResult.Val == 0 && RHSResult.Val == 1) { 6673 // Rare case where the RHS has a comma "side-effect"; we need 6674 // to actually check the condition to see whether the side 6675 // with the comma is evaluated. 6676 if ((Exp->getOpcode() == BO_LAnd) != 6677 (Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0)) 6678 return RHSResult; 6679 return NoDiag(); 6680 } 6681 6682 if (LHSResult.Val >= RHSResult.Val) 6683 return LHSResult; 6684 return RHSResult; 6685 } 6686 } 6687 } 6688 case Expr::ImplicitCastExprClass: 6689 case Expr::CStyleCastExprClass: 6690 case Expr::CXXFunctionalCastExprClass: 6691 case Expr::CXXStaticCastExprClass: 6692 case Expr::CXXReinterpretCastExprClass: 6693 case Expr::CXXConstCastExprClass: 6694 case Expr::ObjCBridgedCastExprClass: { 6695 const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr(); 6696 if (isa<ExplicitCastExpr>(E)) { 6697 if (const FloatingLiteral *FL 6698 = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) { 6699 unsigned DestWidth = Ctx.getIntWidth(E->getType()); 6700 bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType(); 6701 APSInt IgnoredVal(DestWidth, !DestSigned); 6702 bool Ignored; 6703 // If the value does not fit in the destination type, the behavior is 6704 // undefined, so we are not required to treat it as a constant 6705 // expression. 6706 if (FL->getValue().convertToInteger(IgnoredVal, 6707 llvm::APFloat::rmTowardZero, 6708 &Ignored) & APFloat::opInvalidOp) 6709 return ICEDiag(2, E->getLocStart()); 6710 return NoDiag(); 6711 } 6712 } 6713 switch (cast<CastExpr>(E)->getCastKind()) { 6714 case CK_LValueToRValue: 6715 case CK_AtomicToNonAtomic: 6716 case CK_NonAtomicToAtomic: 6717 case CK_NoOp: 6718 case CK_IntegralToBoolean: 6719 case CK_IntegralCast: 6720 return CheckICE(SubExpr, Ctx); 6721 default: 6722 return ICEDiag(2, E->getLocStart()); 6723 } 6724 } 6725 case Expr::BinaryConditionalOperatorClass: { 6726 const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E); 6727 ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx); 6728 if (CommonResult.Val == 2) return CommonResult; 6729 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); 6730 if (FalseResult.Val == 2) return FalseResult; 6731 if (CommonResult.Val == 1) return CommonResult; 6732 if (FalseResult.Val == 1 && 6733 Exp->getCommon()->EvaluateKnownConstInt(Ctx) == 0) return NoDiag(); 6734 return FalseResult; 6735 } 6736 case Expr::ConditionalOperatorClass: { 6737 const ConditionalOperator *Exp = cast<ConditionalOperator>(E); 6738 // If the condition (ignoring parens) is a __builtin_constant_p call, 6739 // then only the true side is actually considered in an integer constant 6740 // expression, and it is fully evaluated. This is an important GNU 6741 // extension. See GCC PR38377 for discussion. 6742 if (const CallExpr *CallCE 6743 = dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts())) 6744 if (CallCE->isBuiltinCall() == Builtin::BI__builtin_constant_p) 6745 return CheckEvalInICE(E, Ctx); 6746 ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx); 6747 if (CondResult.Val == 2) 6748 return CondResult; 6749 6750 ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx); 6751 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); 6752 6753 if (TrueResult.Val == 2) 6754 return TrueResult; 6755 if (FalseResult.Val == 2) 6756 return FalseResult; 6757 if (CondResult.Val == 1) 6758 return CondResult; 6759 if (TrueResult.Val == 0 && FalseResult.Val == 0) 6760 return NoDiag(); 6761 // Rare case where the diagnostics depend on which side is evaluated 6762 // Note that if we get here, CondResult is 0, and at least one of 6763 // TrueResult and FalseResult is non-zero. 6764 if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0) { 6765 return FalseResult; 6766 } 6767 return TrueResult; 6768 } 6769 case Expr::CXXDefaultArgExprClass: 6770 return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx); 6771 case Expr::ChooseExprClass: { 6772 return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(Ctx), Ctx); 6773 } 6774 } 6775 6776 llvm_unreachable("Invalid StmtClass!"); 6777 } 6778 6779 /// Evaluate an expression as a C++11 integral constant expression. 6780 static bool EvaluateCPlusPlus11IntegralConstantExpr(ASTContext &Ctx, 6781 const Expr *E, 6782 llvm::APSInt *Value, 6783 SourceLocation *Loc) { 6784 if (!E->getType()->isIntegralOrEnumerationType()) { 6785 if (Loc) *Loc = E->getExprLoc(); 6786 return false; 6787 } 6788 6789 APValue Result; 6790 if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc)) 6791 return false; 6792 6793 assert(Result.isInt() && "pointer cast to int is not an ICE"); 6794 if (Value) *Value = Result.getInt(); 6795 return true; 6796 } 6797 6798 bool Expr::isIntegerConstantExpr(ASTContext &Ctx, SourceLocation *Loc) const { 6799 if (Ctx.getLangOpts().CPlusPlus0x) 6800 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, 0, Loc); 6801 6802 ICEDiag d = CheckICE(this, Ctx); 6803 if (d.Val != 0) { 6804 if (Loc) *Loc = d.Loc; 6805 return false; 6806 } 6807 return true; 6808 } 6809 6810 bool Expr::isIntegerConstantExpr(llvm::APSInt &Value, ASTContext &Ctx, 6811 SourceLocation *Loc, bool isEvaluated) const { 6812 if (Ctx.getLangOpts().CPlusPlus0x) 6813 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc); 6814 6815 if (!isIntegerConstantExpr(Ctx, Loc)) 6816 return false; 6817 if (!EvaluateAsInt(Value, Ctx)) 6818 llvm_unreachable("ICE cannot be evaluated!"); 6819 return true; 6820 } 6821 6822 bool Expr::isCXX98IntegralConstantExpr(ASTContext &Ctx) const { 6823 return CheckICE(this, Ctx).Val == 0; 6824 } 6825 6826 bool Expr::isCXX11ConstantExpr(ASTContext &Ctx, APValue *Result, 6827 SourceLocation *Loc) const { 6828 // We support this checking in C++98 mode in order to diagnose compatibility 6829 // issues. 6830 assert(Ctx.getLangOpts().CPlusPlus); 6831 6832 // Build evaluation settings. 6833 Expr::EvalStatus Status; 6834 llvm::SmallVector<PartialDiagnosticAt, 8> Diags; 6835 Status.Diag = &Diags; 6836 EvalInfo Info(Ctx, Status); 6837 6838 APValue Scratch; 6839 bool IsConstExpr = ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch); 6840 6841 if (!Diags.empty()) { 6842 IsConstExpr = false; 6843 if (Loc) *Loc = Diags[0].first; 6844 } else if (!IsConstExpr) { 6845 // FIXME: This shouldn't happen. 6846 if (Loc) *Loc = getExprLoc(); 6847 } 6848 6849 return IsConstExpr; 6850 } 6851 6852 bool Expr::isPotentialConstantExpr(const FunctionDecl *FD, 6853 llvm::SmallVectorImpl< 6854 PartialDiagnosticAt> &Diags) { 6855 // FIXME: It would be useful to check constexpr function templates, but at the 6856 // moment the constant expression evaluator cannot cope with the non-rigorous 6857 // ASTs which we build for dependent expressions. 6858 if (FD->isDependentContext()) 6859 return true; 6860 6861 Expr::EvalStatus Status; 6862 Status.Diag = &Diags; 6863 6864 EvalInfo Info(FD->getASTContext(), Status); 6865 Info.CheckingPotentialConstantExpression = true; 6866 6867 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); 6868 const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : 0; 6869 6870 // FIXME: Fabricate an arbitrary expression on the stack and pretend that it 6871 // is a temporary being used as the 'this' pointer. 6872 LValue This; 6873 ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy); 6874 This.set(&VIE, Info.CurrentCall->Index); 6875 6876 ArrayRef<const Expr*> Args; 6877 6878 SourceLocation Loc = FD->getLocation(); 6879 6880 APValue Scratch; 6881 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) 6882 HandleConstructorCall(Loc, This, Args, CD, Info, Scratch); 6883 else 6884 HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : 0, 6885 Args, FD->getBody(), Info, Scratch); 6886 6887 return Diags.empty(); 6888 } 6889