clang  8.0.0svn
ExprConstant.cpp
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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 / C++1y rules only, at the moment), or, if folding failed
27 // too, 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"
39 #include "clang/AST/ASTLambda.h"
40 #include "clang/AST/CharUnits.h"
41 #include "clang/AST/Expr.h"
42 #include "clang/AST/OSLog.h"
43 #include "clang/AST/RecordLayout.h"
44 #include "clang/AST/StmtVisitor.h"
45 #include "clang/AST/TypeLoc.h"
46 #include "clang/Basic/Builtins.h"
47 #include "clang/Basic/TargetInfo.h"
48 #include "llvm/Support/SaveAndRestore.h"
49 #include "llvm/Support/raw_ostream.h"
50 #include <cstring>
51 #include <functional>
52 
53 #define DEBUG_TYPE "exprconstant"
54 
55 using namespace clang;
56 using llvm::APSInt;
57 using llvm::APFloat;
58 
59 static bool IsGlobalLValue(APValue::LValueBase B);
60 
61 namespace {
62  struct LValue;
63  struct CallStackFrame;
64  struct EvalInfo;
65 
66  static QualType getType(APValue::LValueBase B) {
67  if (!B) return QualType();
68  if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
69  // FIXME: It's unclear where we're supposed to take the type from, and
70  // this actually matters for arrays of unknown bound. Eg:
71  //
72  // extern int arr[]; void f() { extern int arr[3]; };
73  // constexpr int *p = &arr[1]; // valid?
74  //
75  // For now, we take the array bound from the most recent declaration.
76  for (auto *Redecl = cast<ValueDecl>(D->getMostRecentDecl()); Redecl;
77  Redecl = cast_or_null<ValueDecl>(Redecl->getPreviousDecl())) {
78  QualType T = Redecl->getType();
79  if (!T->isIncompleteArrayType())
80  return T;
81  }
82  return D->getType();
83  }
84 
85  const Expr *Base = B.get<const Expr*>();
86 
87  // For a materialized temporary, the type of the temporary we materialized
88  // may not be the type of the expression.
89  if (const MaterializeTemporaryExpr *MTE =
90  dyn_cast<MaterializeTemporaryExpr>(Base)) {
93  const Expr *Temp = MTE->GetTemporaryExpr();
94  const Expr *Inner = Temp->skipRValueSubobjectAdjustments(CommaLHSs,
95  Adjustments);
96  // Keep any cv-qualifiers from the reference if we generated a temporary
97  // for it directly. Otherwise use the type after adjustment.
98  if (!Adjustments.empty())
99  return Inner->getType();
100  }
101 
102  return Base->getType();
103  }
104 
105  /// Get an LValue path entry, which is known to not be an array index, as a
106  /// field or base class.
107  static
110  Value.setFromOpaqueValue(E.BaseOrMember);
111  return Value;
112  }
113 
114  /// Get an LValue path entry, which is known to not be an array index, as a
115  /// field declaration.
116  static const FieldDecl *getAsField(APValue::LValuePathEntry E) {
117  return dyn_cast<FieldDecl>(getAsBaseOrMember(E).getPointer());
118  }
119  /// Get an LValue path entry, which is known to not be an array index, as a
120  /// base class declaration.
121  static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) {
122  return dyn_cast<CXXRecordDecl>(getAsBaseOrMember(E).getPointer());
123  }
124  /// Determine whether this LValue path entry for a base class names a virtual
125  /// base class.
126  static bool isVirtualBaseClass(APValue::LValuePathEntry E) {
127  return getAsBaseOrMember(E).getInt();
128  }
129 
130  /// Given a CallExpr, try to get the alloc_size attribute. May return null.
131  static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) {
132  const FunctionDecl *Callee = CE->getDirectCallee();
133  return Callee ? Callee->getAttr<AllocSizeAttr>() : nullptr;
134  }
135 
136  /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr.
137  /// This will look through a single cast.
138  ///
139  /// Returns null if we couldn't unwrap a function with alloc_size.
140  static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) {
141  if (!E->getType()->isPointerType())
142  return nullptr;
143 
144  E = E->IgnoreParens();
145  // If we're doing a variable assignment from e.g. malloc(N), there will
146  // probably be a cast of some kind. In exotic cases, we might also see a
147  // top-level ExprWithCleanups. Ignore them either way.
148  if (const auto *FE = dyn_cast<FullExpr>(E))
149  E = FE->getSubExpr()->IgnoreParens();
150 
151  if (const auto *Cast = dyn_cast<CastExpr>(E))
152  E = Cast->getSubExpr()->IgnoreParens();
153 
154  if (const auto *CE = dyn_cast<CallExpr>(E))
155  return getAllocSizeAttr(CE) ? CE : nullptr;
156  return nullptr;
157  }
158 
159  /// Determines whether or not the given Base contains a call to a function
160  /// with the alloc_size attribute.
161  static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) {
162  const auto *E = Base.dyn_cast<const Expr *>();
163  return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E);
164  }
165 
166  /// The bound to claim that an array of unknown bound has.
167  /// The value in MostDerivedArraySize is undefined in this case. So, set it
168  /// to an arbitrary value that's likely to loudly break things if it's used.
169  static const uint64_t AssumedSizeForUnsizedArray =
171 
172  /// Determines if an LValue with the given LValueBase will have an unsized
173  /// array in its designator.
174  /// Find the path length and type of the most-derived subobject in the given
175  /// path, and find the size of the containing array, if any.
176  static unsigned
177  findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
179  uint64_t &ArraySize, QualType &Type, bool &IsArray,
180  bool &FirstEntryIsUnsizedArray) {
181  // This only accepts LValueBases from APValues, and APValues don't support
182  // arrays that lack size info.
183  assert(!isBaseAnAllocSizeCall(Base) &&
184  "Unsized arrays shouldn't appear here");
185  unsigned MostDerivedLength = 0;
186  Type = getType(Base);
187 
188  for (unsigned I = 0, N = Path.size(); I != N; ++I) {
189  if (Type->isArrayType()) {
190  const ArrayType *AT = Ctx.getAsArrayType(Type);
191  Type = AT->getElementType();
192  MostDerivedLength = I + 1;
193  IsArray = true;
194 
195  if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
196  ArraySize = CAT->getSize().getZExtValue();
197  } else {
198  assert(I == 0 && "unexpected unsized array designator");
199  FirstEntryIsUnsizedArray = true;
200  ArraySize = AssumedSizeForUnsizedArray;
201  }
202  } else if (Type->isAnyComplexType()) {
203  const ComplexType *CT = Type->castAs<ComplexType>();
204  Type = CT->getElementType();
205  ArraySize = 2;
206  MostDerivedLength = I + 1;
207  IsArray = true;
208  } else if (const FieldDecl *FD = getAsField(Path[I])) {
209  Type = FD->getType();
210  ArraySize = 0;
211  MostDerivedLength = I + 1;
212  IsArray = false;
213  } else {
214  // Path[I] describes a base class.
215  ArraySize = 0;
216  IsArray = false;
217  }
218  }
219  return MostDerivedLength;
220  }
221 
222  // The order of this enum is important for diagnostics.
224  CSK_Base, CSK_Derived, CSK_Field, CSK_ArrayToPointer, CSK_ArrayIndex,
225  CSK_This, CSK_Real, CSK_Imag
226  };
227 
228  /// A path from a glvalue to a subobject of that glvalue.
229  struct SubobjectDesignator {
230  /// True if the subobject was named in a manner not supported by C++11. Such
231  /// lvalues can still be folded, but they are not core constant expressions
232  /// and we cannot perform lvalue-to-rvalue conversions on them.
233  unsigned Invalid : 1;
234 
235  /// Is this a pointer one past the end of an object?
236  unsigned IsOnePastTheEnd : 1;
237 
238  /// Indicator of whether the first entry is an unsized array.
239  unsigned FirstEntryIsAnUnsizedArray : 1;
240 
241  /// Indicator of whether the most-derived object is an array element.
242  unsigned MostDerivedIsArrayElement : 1;
243 
244  /// The length of the path to the most-derived object of which this is a
245  /// subobject.
246  unsigned MostDerivedPathLength : 28;
247 
248  /// The size of the array of which the most-derived object is an element.
249  /// This will always be 0 if the most-derived object is not an array
250  /// element. 0 is not an indicator of whether or not the most-derived object
251  /// is an array, however, because 0-length arrays are allowed.
252  ///
253  /// If the current array is an unsized array, the value of this is
254  /// undefined.
255  uint64_t MostDerivedArraySize;
256 
257  /// The type of the most derived object referred to by this address.
258  QualType MostDerivedType;
259 
260  typedef APValue::LValuePathEntry PathEntry;
261 
262  /// The entries on the path from the glvalue to the designated subobject.
264 
265  SubobjectDesignator() : Invalid(true) {}
266 
267  explicit SubobjectDesignator(QualType T)
268  : Invalid(false), IsOnePastTheEnd(false),
269  FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
270  MostDerivedPathLength(0), MostDerivedArraySize(0),
271  MostDerivedType(T) {}
272 
273  SubobjectDesignator(ASTContext &Ctx, const APValue &V)
274  : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false),
275  FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
276  MostDerivedPathLength(0), MostDerivedArraySize(0) {
277  assert(V.isLValue() && "Non-LValue used to make an LValue designator?");
278  if (!Invalid) {
279  IsOnePastTheEnd = V.isLValueOnePastTheEnd();
280  ArrayRef<PathEntry> VEntries = V.getLValuePath();
281  Entries.insert(Entries.end(), VEntries.begin(), VEntries.end());
282  if (V.getLValueBase()) {
283  bool IsArray = false;
284  bool FirstIsUnsizedArray = false;
285  MostDerivedPathLength = findMostDerivedSubobject(
286  Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
287  MostDerivedType, IsArray, FirstIsUnsizedArray);
288  MostDerivedIsArrayElement = IsArray;
289  FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
290  }
291  }
292  }
293 
294  void setInvalid() {
295  Invalid = true;
296  Entries.clear();
297  }
298 
299  /// Determine whether the most derived subobject is an array without a
300  /// known bound.
301  bool isMostDerivedAnUnsizedArray() const {
302  assert(!Invalid && "Calling this makes no sense on invalid designators");
303  return Entries.size() == 1 && FirstEntryIsAnUnsizedArray;
304  }
305 
306  /// Determine what the most derived array's size is. Results in an assertion
307  /// failure if the most derived array lacks a size.
308  uint64_t getMostDerivedArraySize() const {
309  assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size");
310  return MostDerivedArraySize;
311  }
312 
313  /// Determine whether this is a one-past-the-end pointer.
314  bool isOnePastTheEnd() const {
315  assert(!Invalid);
316  if (IsOnePastTheEnd)
317  return true;
318  if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement &&
319  Entries[MostDerivedPathLength - 1].ArrayIndex == MostDerivedArraySize)
320  return true;
321  return false;
322  }
323 
324  /// Get the range of valid index adjustments in the form
325  /// {maximum value that can be subtracted from this pointer,
326  /// maximum value that can be added to this pointer}
327  std::pair<uint64_t, uint64_t> validIndexAdjustments() {
328  if (Invalid || isMostDerivedAnUnsizedArray())
329  return {0, 0};
330 
331  // [expr.add]p4: For the purposes of these operators, a pointer to a
332  // nonarray object behaves the same as a pointer to the first element of
333  // an array of length one with the type of the object as its element type.
334  bool IsArray = MostDerivedPathLength == Entries.size() &&
335  MostDerivedIsArrayElement;
336  uint64_t ArrayIndex =
337  IsArray ? Entries.back().ArrayIndex : (uint64_t)IsOnePastTheEnd;
338  uint64_t ArraySize =
339  IsArray ? getMostDerivedArraySize() : (uint64_t)1;
340  return {ArrayIndex, ArraySize - ArrayIndex};
341  }
342 
343  /// Check that this refers to a valid subobject.
344  bool isValidSubobject() const {
345  if (Invalid)
346  return false;
347  return !isOnePastTheEnd();
348  }
349  /// Check that this refers to a valid subobject, and if not, produce a
350  /// relevant diagnostic and set the designator as invalid.
351  bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK);
352 
353  /// Get the type of the designated object.
354  QualType getType(ASTContext &Ctx) const {
355  assert(!Invalid && "invalid designator has no subobject type");
356  return MostDerivedPathLength == Entries.size()
357  ? MostDerivedType
358  : Ctx.getRecordType(getAsBaseClass(Entries.back()));
359  }
360 
361  /// Update this designator to refer to the first element within this array.
362  void addArrayUnchecked(const ConstantArrayType *CAT) {
363  PathEntry Entry;
364  Entry.ArrayIndex = 0;
365  Entries.push_back(Entry);
366 
367  // This is a most-derived object.
368  MostDerivedType = CAT->getElementType();
369  MostDerivedIsArrayElement = true;
370  MostDerivedArraySize = CAT->getSize().getZExtValue();
371  MostDerivedPathLength = Entries.size();
372  }
373  /// Update this designator to refer to the first element within the array of
374  /// elements of type T. This is an array of unknown size.
375  void addUnsizedArrayUnchecked(QualType ElemTy) {
376  PathEntry Entry;
377  Entry.ArrayIndex = 0;
378  Entries.push_back(Entry);
379 
380  MostDerivedType = ElemTy;
381  MostDerivedIsArrayElement = true;
382  // The value in MostDerivedArraySize is undefined in this case. So, set it
383  // to an arbitrary value that's likely to loudly break things if it's
384  // used.
385  MostDerivedArraySize = AssumedSizeForUnsizedArray;
386  MostDerivedPathLength = Entries.size();
387  }
388  /// Update this designator to refer to the given base or member of this
389  /// object.
390  void addDeclUnchecked(const Decl *D, bool Virtual = false) {
391  PathEntry Entry;
392  APValue::BaseOrMemberType Value(D, Virtual);
393  Entry.BaseOrMember = Value.getOpaqueValue();
394  Entries.push_back(Entry);
395 
396  // If this isn't a base class, it's a new most-derived object.
397  if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
398  MostDerivedType = FD->getType();
399  MostDerivedIsArrayElement = false;
400  MostDerivedArraySize = 0;
401  MostDerivedPathLength = Entries.size();
402  }
403  }
404  /// Update this designator to refer to the given complex component.
405  void addComplexUnchecked(QualType EltTy, bool Imag) {
406  PathEntry Entry;
407  Entry.ArrayIndex = Imag;
408  Entries.push_back(Entry);
409 
410  // This is technically a most-derived object, though in practice this
411  // is unlikely to matter.
412  MostDerivedType = EltTy;
413  MostDerivedIsArrayElement = true;
414  MostDerivedArraySize = 2;
415  MostDerivedPathLength = Entries.size();
416  }
417  void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E);
418  void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
419  const APSInt &N);
420  /// Add N to the address of this subobject.
421  void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) {
422  if (Invalid || !N) return;
423  uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue();
424  if (isMostDerivedAnUnsizedArray()) {
425  diagnoseUnsizedArrayPointerArithmetic(Info, E);
426  // Can't verify -- trust that the user is doing the right thing (or if
427  // not, trust that the caller will catch the bad behavior).
428  // FIXME: Should we reject if this overflows, at least?
429  Entries.back().ArrayIndex += TruncatedN;
430  return;
431  }
432 
433  // [expr.add]p4: For the purposes of these operators, a pointer to a
434  // nonarray object behaves the same as a pointer to the first element of
435  // an array of length one with the type of the object as its element type.
436  bool IsArray = MostDerivedPathLength == Entries.size() &&
437  MostDerivedIsArrayElement;
438  uint64_t ArrayIndex =
439  IsArray ? Entries.back().ArrayIndex : (uint64_t)IsOnePastTheEnd;
440  uint64_t ArraySize =
441  IsArray ? getMostDerivedArraySize() : (uint64_t)1;
442 
443  if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) {
444  // Calculate the actual index in a wide enough type, so we can include
445  // it in the note.
446  N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65));
447  (llvm::APInt&)N += ArrayIndex;
448  assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index");
449  diagnosePointerArithmetic(Info, E, N);
450  setInvalid();
451  return;
452  }
453 
454  ArrayIndex += TruncatedN;
455  assert(ArrayIndex <= ArraySize &&
456  "bounds check succeeded for out-of-bounds index");
457 
458  if (IsArray)
459  Entries.back().ArrayIndex = ArrayIndex;
460  else
461  IsOnePastTheEnd = (ArrayIndex != 0);
462  }
463  };
464 
465  /// A stack frame in the constexpr call stack.
466  struct CallStackFrame {
467  EvalInfo &Info;
468 
469  /// Parent - The caller of this stack frame.
470  CallStackFrame *Caller;
471 
472  /// Callee - The function which was called.
473  const FunctionDecl *Callee;
474 
475  /// This - The binding for the this pointer in this call, if any.
476  const LValue *This;
477 
478  /// Arguments - Parameter bindings for this function call, indexed by
479  /// parameters' function scope indices.
480  APValue *Arguments;
481 
482  // Note that we intentionally use std::map here so that references to
483  // values are stable.
484  typedef std::pair<const void *, unsigned> MapKeyTy;
485  typedef std::map<MapKeyTy, APValue> MapTy;
486  /// Temporaries - Temporary lvalues materialized within this stack frame.
487  MapTy Temporaries;
488 
489  /// CallLoc - The location of the call expression for this call.
490  SourceLocation CallLoc;
491 
492  /// Index - The call index of this call.
493  unsigned Index;
494 
495  /// The stack of integers for tracking version numbers for temporaries.
496  SmallVector<unsigned, 2> TempVersionStack = {1};
497  unsigned CurTempVersion = TempVersionStack.back();
498 
499  unsigned getTempVersion() const { return TempVersionStack.back(); }
500 
501  void pushTempVersion() {
502  TempVersionStack.push_back(++CurTempVersion);
503  }
504 
505  void popTempVersion() {
506  TempVersionStack.pop_back();
507  }
508 
509  // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact
510  // on the overall stack usage of deeply-recursing constexpr evaluations.
511  // (We should cache this map rather than recomputing it repeatedly.)
512  // But let's try this and see how it goes; we can look into caching the map
513  // as a later change.
514 
515  /// LambdaCaptureFields - Mapping from captured variables/this to
516  /// corresponding data members in the closure class.
517  llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields;
518  FieldDecl *LambdaThisCaptureField;
519 
520  CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
521  const FunctionDecl *Callee, const LValue *This,
522  APValue *Arguments);
523  ~CallStackFrame();
524 
525  // Return the temporary for Key whose version number is Version.
526  APValue *getTemporary(const void *Key, unsigned Version) {
527  MapKeyTy KV(Key, Version);
528  auto LB = Temporaries.lower_bound(KV);
529  if (LB != Temporaries.end() && LB->first == KV)
530  return &LB->second;
531  // Pair (Key,Version) wasn't found in the map. Check that no elements
532  // in the map have 'Key' as their key.
533  assert((LB == Temporaries.end() || LB->first.first != Key) &&
534  (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) &&
535  "Element with key 'Key' found in map");
536  return nullptr;
537  }
538 
539  // Return the current temporary for Key in the map.
540  APValue *getCurrentTemporary(const void *Key) {
541  auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
542  if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
543  return &std::prev(UB)->second;
544  return nullptr;
545  }
546 
547  // Return the version number of the current temporary for Key.
548  unsigned getCurrentTemporaryVersion(const void *Key) const {
549  auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
550  if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
551  return std::prev(UB)->first.second;
552  return 0;
553  }
554 
555  APValue &createTemporary(const void *Key, bool IsLifetimeExtended);
556  };
557 
558  /// Temporarily override 'this'.
559  class ThisOverrideRAII {
560  public:
561  ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
562  : Frame(Frame), OldThis(Frame.This) {
563  if (Enable)
564  Frame.This = NewThis;
565  }
566  ~ThisOverrideRAII() {
567  Frame.This = OldThis;
568  }
569  private:
570  CallStackFrame &Frame;
571  const LValue *OldThis;
572  };
573 
574  /// A partial diagnostic which we might know in advance that we are not going
575  /// to emit.
576  class OptionalDiagnostic {
578 
579  public:
580  explicit OptionalDiagnostic(PartialDiagnostic *Diag = nullptr)
581  : Diag(Diag) {}
582 
583  template<typename T>
584  OptionalDiagnostic &operator<<(const T &v) {
585  if (Diag)
586  *Diag << v;
587  return *this;
588  }
589 
590  OptionalDiagnostic &operator<<(const APSInt &I) {
591  if (Diag) {
592  SmallVector<char, 32> Buffer;
593  I.toString(Buffer);
594  *Diag << StringRef(Buffer.data(), Buffer.size());
595  }
596  return *this;
597  }
598 
599  OptionalDiagnostic &operator<<(const APFloat &F) {
600  if (Diag) {
601  // FIXME: Force the precision of the source value down so we don't
602  // print digits which are usually useless (we don't really care here if
603  // we truncate a digit by accident in edge cases). Ideally,
604  // APFloat::toString would automatically print the shortest
605  // representation which rounds to the correct value, but it's a bit
606  // tricky to implement.
607  unsigned precision =
608  llvm::APFloat::semanticsPrecision(F.getSemantics());
609  precision = (precision * 59 + 195) / 196;
610  SmallVector<char, 32> Buffer;
611  F.toString(Buffer, precision);
612  *Diag << StringRef(Buffer.data(), Buffer.size());
613  }
614  return *this;
615  }
616  };
617 
618  /// A cleanup, and a flag indicating whether it is lifetime-extended.
619  class Cleanup {
620  llvm::PointerIntPair<APValue*, 1, bool> Value;
621 
622  public:
623  Cleanup(APValue *Val, bool IsLifetimeExtended)
624  : Value(Val, IsLifetimeExtended) {}
625 
626  bool isLifetimeExtended() const { return Value.getInt(); }
627  void endLifetime() {
628  *Value.getPointer() = APValue();
629  }
630  };
631 
632  /// EvalInfo - This is a private struct used by the evaluator to capture
633  /// information about a subexpression as it is folded. It retains information
634  /// about the AST context, but also maintains information about the folded
635  /// expression.
636  ///
637  /// If an expression could be evaluated, it is still possible it is not a C
638  /// "integer constant expression" or constant expression. If not, this struct
639  /// captures information about how and why not.
640  ///
641  /// One bit of information passed *into* the request for constant folding
642  /// indicates whether the subexpression is "evaluated" or not according to C
643  /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
644  /// evaluate the expression regardless of what the RHS is, but C only allows
645  /// certain things in certain situations.
646  struct EvalInfo {
647  ASTContext &Ctx;
648 
649  /// EvalStatus - Contains information about the evaluation.
650  Expr::EvalStatus &EvalStatus;
651 
652  /// CurrentCall - The top of the constexpr call stack.
653  CallStackFrame *CurrentCall;
654 
655  /// CallStackDepth - The number of calls in the call stack right now.
656  unsigned CallStackDepth;
657 
658  /// NextCallIndex - The next call index to assign.
659  unsigned NextCallIndex;
660 
661  /// StepsLeft - The remaining number of evaluation steps we're permitted
662  /// to perform. This is essentially a limit for the number of statements
663  /// we will evaluate.
664  unsigned StepsLeft;
665 
666  /// BottomFrame - The frame in which evaluation started. This must be
667  /// initialized after CurrentCall and CallStackDepth.
668  CallStackFrame BottomFrame;
669 
670  /// A stack of values whose lifetimes end at the end of some surrounding
671  /// evaluation frame.
672  llvm::SmallVector<Cleanup, 16> CleanupStack;
673 
674  /// EvaluatingDecl - This is the declaration whose initializer is being
675  /// evaluated, if any.
676  APValue::LValueBase EvaluatingDecl;
677 
678  /// EvaluatingDeclValue - This is the value being constructed for the
679  /// declaration whose initializer is being evaluated, if any.
680  APValue *EvaluatingDeclValue;
681 
682  /// EvaluatingObject - Pair of the AST node that an lvalue represents and
683  /// the call index that that lvalue was allocated in.
684  typedef std::pair<APValue::LValueBase, std::pair<unsigned, unsigned>>
685  EvaluatingObject;
686 
687  /// EvaluatingConstructors - Set of objects that are currently being
688  /// constructed.
689  llvm::DenseSet<EvaluatingObject> EvaluatingConstructors;
690 
691  struct EvaluatingConstructorRAII {
692  EvalInfo &EI;
693  EvaluatingObject Object;
694  bool DidInsert;
695  EvaluatingConstructorRAII(EvalInfo &EI, EvaluatingObject Object)
696  : EI(EI), Object(Object) {
697  DidInsert = EI.EvaluatingConstructors.insert(Object).second;
698  }
699  ~EvaluatingConstructorRAII() {
700  if (DidInsert) EI.EvaluatingConstructors.erase(Object);
701  }
702  };
703 
704  bool isEvaluatingConstructor(APValue::LValueBase Decl, unsigned CallIndex,
705  unsigned Version) {
706  return EvaluatingConstructors.count(
707  EvaluatingObject(Decl, {CallIndex, Version}));
708  }
709 
710  /// The current array initialization index, if we're performing array
711  /// initialization.
712  uint64_t ArrayInitIndex = -1;
713 
714  /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
715  /// notes attached to it will also be stored, otherwise they will not be.
716  bool HasActiveDiagnostic;
717 
718  /// Have we emitted a diagnostic explaining why we couldn't constant
719  /// fold (not just why it's not strictly a constant expression)?
720  bool HasFoldFailureDiagnostic;
721 
722  /// Whether or not we're currently speculatively evaluating.
723  bool IsSpeculativelyEvaluating;
724 
725  /// Whether or not we're in a context where the front end requires a
726  /// constant value.
727  bool InConstantContext;
728 
729  enum EvaluationMode {
730  /// Evaluate as a constant expression. Stop if we find that the expression
731  /// is not a constant expression.
732  EM_ConstantExpression,
733 
734  /// Evaluate as a potential constant expression. Keep going if we hit a
735  /// construct that we can't evaluate yet (because we don't yet know the
736  /// value of something) but stop if we hit something that could never be
737  /// a constant expression.
738  EM_PotentialConstantExpression,
739 
740  /// Fold the expression to a constant. Stop if we hit a side-effect that
741  /// we can't model.
742  EM_ConstantFold,
743 
744  /// Evaluate the expression looking for integer overflow and similar
745  /// issues. Don't worry about side-effects, and try to visit all
746  /// subexpressions.
747  EM_EvaluateForOverflow,
748 
749  /// Evaluate in any way we know how. Don't worry about side-effects that
750  /// can't be modeled.
751  EM_IgnoreSideEffects,
752 
753  /// Evaluate as a constant expression. Stop if we find that the expression
754  /// is not a constant expression. Some expressions can be retried in the
755  /// optimizer if we don't constant fold them here, but in an unevaluated
756  /// context we try to fold them immediately since the optimizer never
757  /// gets a chance to look at it.
758  EM_ConstantExpressionUnevaluated,
759 
760  /// Evaluate as a potential constant expression. Keep going if we hit a
761  /// construct that we can't evaluate yet (because we don't yet know the
762  /// value of something) but stop if we hit something that could never be
763  /// a constant expression. Some expressions can be retried in the
764  /// optimizer if we don't constant fold them here, but in an unevaluated
765  /// context we try to fold them immediately since the optimizer never
766  /// gets a chance to look at it.
767  EM_PotentialConstantExpressionUnevaluated,
768  } EvalMode;
769 
770  /// Are we checking whether the expression is a potential constant
771  /// expression?
772  bool checkingPotentialConstantExpression() const {
773  return EvalMode == EM_PotentialConstantExpression ||
774  EvalMode == EM_PotentialConstantExpressionUnevaluated;
775  }
776 
777  /// Are we checking an expression for overflow?
778  // FIXME: We should check for any kind of undefined or suspicious behavior
779  // in such constructs, not just overflow.
780  bool checkingForOverflow() { return EvalMode == EM_EvaluateForOverflow; }
781 
782  EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
783  : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
784  CallStackDepth(0), NextCallIndex(1),
785  StepsLeft(getLangOpts().ConstexprStepLimit),
786  BottomFrame(*this, SourceLocation(), nullptr, nullptr, nullptr),
787  EvaluatingDecl((const ValueDecl *)nullptr),
788  EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
789  HasFoldFailureDiagnostic(false), IsSpeculativelyEvaluating(false),
790  InConstantContext(false), EvalMode(Mode) {}
791 
792  void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) {
793  EvaluatingDecl = Base;
794  EvaluatingDeclValue = &Value;
795  EvaluatingConstructors.insert({Base, {0, 0}});
796  }
797 
798  const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); }
799 
800  bool CheckCallLimit(SourceLocation Loc) {
801  // Don't perform any constexpr calls (other than the call we're checking)
802  // when checking a potential constant expression.
803  if (checkingPotentialConstantExpression() && CallStackDepth > 1)
804  return false;
805  if (NextCallIndex == 0) {
806  // NextCallIndex has wrapped around.
807  FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
808  return false;
809  }
810  if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
811  return true;
812  FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
813  << getLangOpts().ConstexprCallDepth;
814  return false;
815  }
816 
817  CallStackFrame *getCallFrame(unsigned CallIndex) {
818  assert(CallIndex && "no call index in getCallFrame");
819  // We will eventually hit BottomFrame, which has Index 1, so Frame can't
820  // be null in this loop.
821  CallStackFrame *Frame = CurrentCall;
822  while (Frame->Index > CallIndex)
823  Frame = Frame->Caller;
824  return (Frame->Index == CallIndex) ? Frame : nullptr;
825  }
826 
827  bool nextStep(const Stmt *S) {
828  if (!StepsLeft) {
829  FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded);
830  return false;
831  }
832  --StepsLeft;
833  return true;
834  }
835 
836  private:
837  /// Add a diagnostic to the diagnostics list.
838  PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId) {
839  PartialDiagnostic PD(DiagId, Ctx.getDiagAllocator());
840  EvalStatus.Diag->push_back(std::make_pair(Loc, PD));
841  return EvalStatus.Diag->back().second;
842  }
843 
844  /// Add notes containing a call stack to the current point of evaluation.
845  void addCallStack(unsigned Limit);
846 
847  private:
848  OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId,
849  unsigned ExtraNotes, bool IsCCEDiag) {
850 
851  if (EvalStatus.Diag) {
852  // If we have a prior diagnostic, it will be noting that the expression
853  // isn't a constant expression. This diagnostic is more important,
854  // unless we require this evaluation to produce a constant expression.
855  //
856  // FIXME: We might want to show both diagnostics to the user in
857  // EM_ConstantFold mode.
858  if (!EvalStatus.Diag->empty()) {
859  switch (EvalMode) {
860  case EM_ConstantFold:
861  case EM_IgnoreSideEffects:
862  case EM_EvaluateForOverflow:
863  if (!HasFoldFailureDiagnostic)
864  break;
865  // We've already failed to fold something. Keep that diagnostic.
866  LLVM_FALLTHROUGH;
867  case EM_ConstantExpression:
868  case EM_PotentialConstantExpression:
869  case EM_ConstantExpressionUnevaluated:
870  case EM_PotentialConstantExpressionUnevaluated:
871  HasActiveDiagnostic = false;
872  return OptionalDiagnostic();
873  }
874  }
875 
876  unsigned CallStackNotes = CallStackDepth - 1;
877  unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit();
878  if (Limit)
879  CallStackNotes = std::min(CallStackNotes, Limit + 1);
880  if (checkingPotentialConstantExpression())
881  CallStackNotes = 0;
882 
883  HasActiveDiagnostic = true;
884  HasFoldFailureDiagnostic = !IsCCEDiag;
885  EvalStatus.Diag->clear();
886  EvalStatus.Diag->reserve(1 + ExtraNotes + CallStackNotes);
887  addDiag(Loc, DiagId);
888  if (!checkingPotentialConstantExpression())
889  addCallStack(Limit);
890  return OptionalDiagnostic(&(*EvalStatus.Diag)[0].second);
891  }
892  HasActiveDiagnostic = false;
893  return OptionalDiagnostic();
894  }
895  public:
896  // Diagnose that the evaluation could not be folded (FF => FoldFailure)
897  OptionalDiagnostic
898  FFDiag(SourceLocation Loc,
899  diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr,
900  unsigned ExtraNotes = 0) {
901  return Diag(Loc, DiagId, ExtraNotes, false);
902  }
903 
904  OptionalDiagnostic FFDiag(const Expr *E, diag::kind DiagId
905  = diag::note_invalid_subexpr_in_const_expr,
906  unsigned ExtraNotes = 0) {
907  if (EvalStatus.Diag)
908  return Diag(E->getExprLoc(), DiagId, ExtraNotes, /*IsCCEDiag*/false);
909  HasActiveDiagnostic = false;
910  return OptionalDiagnostic();
911  }
912 
913  /// Diagnose that the evaluation does not produce a C++11 core constant
914  /// expression.
915  ///
916  /// FIXME: Stop evaluating if we're in EM_ConstantExpression or
917  /// EM_PotentialConstantExpression mode and we produce one of these.
918  OptionalDiagnostic CCEDiag(SourceLocation Loc, diag::kind DiagId
919  = diag::note_invalid_subexpr_in_const_expr,
920  unsigned ExtraNotes = 0) {
921  // Don't override a previous diagnostic. Don't bother collecting
922  // diagnostics if we're evaluating for overflow.
923  if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) {
924  HasActiveDiagnostic = false;
925  return OptionalDiagnostic();
926  }
927  return Diag(Loc, DiagId, ExtraNotes, true);
928  }
929  OptionalDiagnostic CCEDiag(const Expr *E, diag::kind DiagId
930  = diag::note_invalid_subexpr_in_const_expr,
931  unsigned ExtraNotes = 0) {
932  return CCEDiag(E->getExprLoc(), DiagId, ExtraNotes);
933  }
934  /// Add a note to a prior diagnostic.
935  OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId) {
936  if (!HasActiveDiagnostic)
937  return OptionalDiagnostic();
938  return OptionalDiagnostic(&addDiag(Loc, DiagId));
939  }
940 
941  /// Add a stack of notes to a prior diagnostic.
942  void addNotes(ArrayRef<PartialDiagnosticAt> Diags) {
943  if (HasActiveDiagnostic) {
944  EvalStatus.Diag->insert(EvalStatus.Diag->end(),
945  Diags.begin(), Diags.end());
946  }
947  }
948 
949  /// Should we continue evaluation after encountering a side-effect that we
950  /// couldn't model?
951  bool keepEvaluatingAfterSideEffect() {
952  switch (EvalMode) {
953  case EM_PotentialConstantExpression:
954  case EM_PotentialConstantExpressionUnevaluated:
955  case EM_EvaluateForOverflow:
956  case EM_IgnoreSideEffects:
957  return true;
958 
959  case EM_ConstantExpression:
960  case EM_ConstantExpressionUnevaluated:
961  case EM_ConstantFold:
962  return false;
963  }
964  llvm_unreachable("Missed EvalMode case");
965  }
966 
967  /// Note that we have had a side-effect, and determine whether we should
968  /// keep evaluating.
969  bool noteSideEffect() {
970  EvalStatus.HasSideEffects = true;
971  return keepEvaluatingAfterSideEffect();
972  }
973 
974  /// Should we continue evaluation after encountering undefined behavior?
975  bool keepEvaluatingAfterUndefinedBehavior() {
976  switch (EvalMode) {
977  case EM_EvaluateForOverflow:
978  case EM_IgnoreSideEffects:
979  case EM_ConstantFold:
980  return true;
981 
982  case EM_PotentialConstantExpression:
983  case EM_PotentialConstantExpressionUnevaluated:
984  case EM_ConstantExpression:
985  case EM_ConstantExpressionUnevaluated:
986  return false;
987  }
988  llvm_unreachable("Missed EvalMode case");
989  }
990 
991  /// Note that we hit something that was technically undefined behavior, but
992  /// that we can evaluate past it (such as signed overflow or floating-point
993  /// division by zero.)
994  bool noteUndefinedBehavior() {
995  EvalStatus.HasUndefinedBehavior = true;
996  return keepEvaluatingAfterUndefinedBehavior();
997  }
998 
999  /// Should we continue evaluation as much as possible after encountering a
1000  /// construct which can't be reduced to a value?
1001  bool keepEvaluatingAfterFailure() {
1002  if (!StepsLeft)
1003  return false;
1004 
1005  switch (EvalMode) {
1006  case EM_PotentialConstantExpression:
1007  case EM_PotentialConstantExpressionUnevaluated:
1008  case EM_EvaluateForOverflow:
1009  return true;
1010 
1011  case EM_ConstantExpression:
1012  case EM_ConstantExpressionUnevaluated:
1013  case EM_ConstantFold:
1014  case EM_IgnoreSideEffects:
1015  return false;
1016  }
1017  llvm_unreachable("Missed EvalMode case");
1018  }
1019 
1020  /// Notes that we failed to evaluate an expression that other expressions
1021  /// directly depend on, and determine if we should keep evaluating. This
1022  /// should only be called if we actually intend to keep evaluating.
1023  ///
1024  /// Call noteSideEffect() instead if we may be able to ignore the value that
1025  /// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
1026  ///
1027  /// (Foo(), 1) // use noteSideEffect
1028  /// (Foo() || true) // use noteSideEffect
1029  /// Foo() + 1 // use noteFailure
1030  LLVM_NODISCARD bool noteFailure() {
1031  // Failure when evaluating some expression often means there is some
1032  // subexpression whose evaluation was skipped. Therefore, (because we
1033  // don't track whether we skipped an expression when unwinding after an
1034  // evaluation failure) every evaluation failure that bubbles up from a
1035  // subexpression implies that a side-effect has potentially happened. We
1036  // skip setting the HasSideEffects flag to true until we decide to
1037  // continue evaluating after that point, which happens here.
1038  bool KeepGoing = keepEvaluatingAfterFailure();
1039  EvalStatus.HasSideEffects |= KeepGoing;
1040  return KeepGoing;
1041  }
1042 
1043  class ArrayInitLoopIndex {
1044  EvalInfo &Info;
1045  uint64_t OuterIndex;
1046 
1047  public:
1048  ArrayInitLoopIndex(EvalInfo &Info)
1049  : Info(Info), OuterIndex(Info.ArrayInitIndex) {
1050  Info.ArrayInitIndex = 0;
1051  }
1052  ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
1053 
1054  operator uint64_t&() { return Info.ArrayInitIndex; }
1055  };
1056  };
1057 
1058  /// Object used to treat all foldable expressions as constant expressions.
1059  struct FoldConstant {
1060  EvalInfo &Info;
1061  bool Enabled;
1062  bool HadNoPriorDiags;
1063  EvalInfo::EvaluationMode OldMode;
1064 
1065  explicit FoldConstant(EvalInfo &Info, bool Enabled)
1066  : Info(Info),
1067  Enabled(Enabled),
1068  HadNoPriorDiags(Info.EvalStatus.Diag &&
1069  Info.EvalStatus.Diag->empty() &&
1070  !Info.EvalStatus.HasSideEffects),
1071  OldMode(Info.EvalMode) {
1072  if (Enabled &&
1073  (Info.EvalMode == EvalInfo::EM_ConstantExpression ||
1074  Info.EvalMode == EvalInfo::EM_ConstantExpressionUnevaluated))
1075  Info.EvalMode = EvalInfo::EM_ConstantFold;
1076  }
1077  void keepDiagnostics() { Enabled = false; }
1078  ~FoldConstant() {
1079  if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
1080  !Info.EvalStatus.HasSideEffects)
1081  Info.EvalStatus.Diag->clear();
1082  Info.EvalMode = OldMode;
1083  }
1084  };
1085 
1086  /// RAII object used to set the current evaluation mode to ignore
1087  /// side-effects.
1088  struct IgnoreSideEffectsRAII {
1089  EvalInfo &Info;
1090  EvalInfo::EvaluationMode OldMode;
1091  explicit IgnoreSideEffectsRAII(EvalInfo &Info)
1092  : Info(Info), OldMode(Info.EvalMode) {
1093  if (!Info.checkingPotentialConstantExpression())
1094  Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
1095  }
1096 
1097  ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; }
1098  };
1099 
1100  /// RAII object used to optionally suppress diagnostics and side-effects from
1101  /// a speculative evaluation.
1102  class SpeculativeEvaluationRAII {
1103  EvalInfo *Info = nullptr;
1104  Expr::EvalStatus OldStatus;
1105  bool OldIsSpeculativelyEvaluating;
1106 
1107  void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
1108  Info = Other.Info;
1109  OldStatus = Other.OldStatus;
1110  OldIsSpeculativelyEvaluating = Other.OldIsSpeculativelyEvaluating;
1111  Other.Info = nullptr;
1112  }
1113 
1114  void maybeRestoreState() {
1115  if (!Info)
1116  return;
1117 
1118  Info->EvalStatus = OldStatus;
1119  Info->IsSpeculativelyEvaluating = OldIsSpeculativelyEvaluating;
1120  }
1121 
1122  public:
1123  SpeculativeEvaluationRAII() = default;
1124 
1125  SpeculativeEvaluationRAII(
1126  EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
1127  : Info(&Info), OldStatus(Info.EvalStatus),
1128  OldIsSpeculativelyEvaluating(Info.IsSpeculativelyEvaluating) {
1129  Info.EvalStatus.Diag = NewDiag;
1130  Info.IsSpeculativelyEvaluating = true;
1131  }
1132 
1133  SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
1134  SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
1135  moveFromAndCancel(std::move(Other));
1136  }
1137 
1138  SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
1139  maybeRestoreState();
1140  moveFromAndCancel(std::move(Other));
1141  return *this;
1142  }
1143 
1144  ~SpeculativeEvaluationRAII() { maybeRestoreState(); }
1145  };
1146 
1147  /// RAII object wrapping a full-expression or block scope, and handling
1148  /// the ending of the lifetime of temporaries created within it.
1149  template<bool IsFullExpression>
1150  class ScopeRAII {
1151  EvalInfo &Info;
1152  unsigned OldStackSize;
1153  public:
1154  ScopeRAII(EvalInfo &Info)
1155  : Info(Info), OldStackSize(Info.CleanupStack.size()) {
1156  // Push a new temporary version. This is needed to distinguish between
1157  // temporaries created in different iterations of a loop.
1158  Info.CurrentCall->pushTempVersion();
1159  }
1160  ~ScopeRAII() {
1161  // Body moved to a static method to encourage the compiler to inline away
1162  // instances of this class.
1163  cleanup(Info, OldStackSize);
1164  Info.CurrentCall->popTempVersion();
1165  }
1166  private:
1167  static void cleanup(EvalInfo &Info, unsigned OldStackSize) {
1168  unsigned NewEnd = OldStackSize;
1169  for (unsigned I = OldStackSize, N = Info.CleanupStack.size();
1170  I != N; ++I) {
1171  if (IsFullExpression && Info.CleanupStack[I].isLifetimeExtended()) {
1172  // Full-expression cleanup of a lifetime-extended temporary: nothing
1173  // to do, just move this cleanup to the right place in the stack.
1174  std::swap(Info.CleanupStack[I], Info.CleanupStack[NewEnd]);
1175  ++NewEnd;
1176  } else {
1177  // End the lifetime of the object.
1178  Info.CleanupStack[I].endLifetime();
1179  }
1180  }
1181  Info.CleanupStack.erase(Info.CleanupStack.begin() + NewEnd,
1182  Info.CleanupStack.end());
1183  }
1184  };
1185  typedef ScopeRAII<false> BlockScopeRAII;
1186  typedef ScopeRAII<true> FullExpressionRAII;
1187 }
1188 
1189 bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
1190  CheckSubobjectKind CSK) {
1191  if (Invalid)
1192  return false;
1193  if (isOnePastTheEnd()) {
1194  Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
1195  << CSK;
1196  setInvalid();
1197  return false;
1198  }
1199  // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
1200  // must actually be at least one array element; even a VLA cannot have a
1201  // bound of zero. And if our index is nonzero, we already had a CCEDiag.
1202  return true;
1203 }
1204 
1205 void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
1206  const Expr *E) {
1207  Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
1208  // Do not set the designator as invalid: we can represent this situation,
1209  // and correct handling of __builtin_object_size requires us to do so.
1210 }
1211 
1212 void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
1213  const Expr *E,
1214  const APSInt &N) {
1215  // If we're complaining, we must be able to statically determine the size of
1216  // the most derived array.
1217  if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
1218  Info.CCEDiag(E, diag::note_constexpr_array_index)
1219  << N << /*array*/ 0
1220  << static_cast<unsigned>(getMostDerivedArraySize());
1221  else
1222  Info.CCEDiag(E, diag::note_constexpr_array_index)
1223  << N << /*non-array*/ 1;
1224  setInvalid();
1225 }
1226 
1227 CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
1228  const FunctionDecl *Callee, const LValue *This,
1229  APValue *Arguments)
1230  : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
1231  Arguments(Arguments), CallLoc(CallLoc), Index(Info.NextCallIndex++) {
1232  Info.CurrentCall = this;
1233  ++Info.CallStackDepth;
1234 }
1235 
1236 CallStackFrame::~CallStackFrame() {
1237  assert(Info.CurrentCall == this && "calls retired out of order");
1238  --Info.CallStackDepth;
1239  Info.CurrentCall = Caller;
1240 }
1241 
1242 APValue &CallStackFrame::createTemporary(const void *Key,
1243  bool IsLifetimeExtended) {
1244  unsigned Version = Info.CurrentCall->getTempVersion();
1245  APValue &Result = Temporaries[MapKeyTy(Key, Version)];
1246  assert(Result.isUninit() && "temporary created multiple times");
1247  Info.CleanupStack.push_back(Cleanup(&Result, IsLifetimeExtended));
1248  return Result;
1249 }
1250 
1251 static void describeCall(CallStackFrame *Frame, raw_ostream &Out);
1252 
1253 void EvalInfo::addCallStack(unsigned Limit) {
1254  // Determine which calls to skip, if any.
1255  unsigned ActiveCalls = CallStackDepth - 1;
1256  unsigned SkipStart = ActiveCalls, SkipEnd = SkipStart;
1257  if (Limit && Limit < ActiveCalls) {
1258  SkipStart = Limit / 2 + Limit % 2;
1259  SkipEnd = ActiveCalls - Limit / 2;
1260  }
1261 
1262  // Walk the call stack and add the diagnostics.
1263  unsigned CallIdx = 0;
1264  for (CallStackFrame *Frame = CurrentCall; Frame != &BottomFrame;
1265  Frame = Frame->Caller, ++CallIdx) {
1266  // Skip this call?
1267  if (CallIdx >= SkipStart && CallIdx < SkipEnd) {
1268  if (CallIdx == SkipStart) {
1269  // Note that we're skipping calls.
1270  addDiag(Frame->CallLoc, diag::note_constexpr_calls_suppressed)
1271  << unsigned(ActiveCalls - Limit);
1272  }
1273  continue;
1274  }
1275 
1276  // Use a different note for an inheriting constructor, because from the
1277  // user's perspective it's not really a function at all.
1278  if (auto *CD = dyn_cast_or_null<CXXConstructorDecl>(Frame->Callee)) {
1279  if (CD->isInheritingConstructor()) {
1280  addDiag(Frame->CallLoc, diag::note_constexpr_inherited_ctor_call_here)
1281  << CD->getParent();
1282  continue;
1283  }
1284  }
1285 
1286  SmallVector<char, 128> Buffer;
1287  llvm::raw_svector_ostream Out(Buffer);
1288  describeCall(Frame, Out);
1289  addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str();
1290  }
1291 }
1292 
1293 /// Kinds of access we can perform on an object, for diagnostics.
1299 };
1300 
1301 namespace {
1302  struct ComplexValue {
1303  private:
1304  bool IsInt;
1305 
1306  public:
1307  APSInt IntReal, IntImag;
1308  APFloat FloatReal, FloatImag;
1309 
1310  ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
1311 
1312  void makeComplexFloat() { IsInt = false; }
1313  bool isComplexFloat() const { return !IsInt; }
1314  APFloat &getComplexFloatReal() { return FloatReal; }
1315  APFloat &getComplexFloatImag() { return FloatImag; }
1316 
1317  void makeComplexInt() { IsInt = true; }
1318  bool isComplexInt() const { return IsInt; }
1319  APSInt &getComplexIntReal() { return IntReal; }
1320  APSInt &getComplexIntImag() { return IntImag; }
1321 
1322  void moveInto(APValue &v) const {
1323  if (isComplexFloat())
1324  v = APValue(FloatReal, FloatImag);
1325  else
1326  v = APValue(IntReal, IntImag);
1327  }
1328  void setFrom(const APValue &v) {
1329  assert(v.isComplexFloat() || v.isComplexInt());
1330  if (v.isComplexFloat()) {
1331  makeComplexFloat();
1332  FloatReal = v.getComplexFloatReal();
1333  FloatImag = v.getComplexFloatImag();
1334  } else {
1335  makeComplexInt();
1336  IntReal = v.getComplexIntReal();
1337  IntImag = v.getComplexIntImag();
1338  }
1339  }
1340  };
1341 
1342  struct LValue {
1343  APValue::LValueBase Base;
1344  CharUnits Offset;
1345  SubobjectDesignator Designator;
1346  bool IsNullPtr : 1;
1347  bool InvalidBase : 1;
1348 
1349  const APValue::LValueBase getLValueBase() const { return Base; }
1350  CharUnits &getLValueOffset() { return Offset; }
1351  const CharUnits &getLValueOffset() const { return Offset; }
1352  SubobjectDesignator &getLValueDesignator() { return Designator; }
1353  const SubobjectDesignator &getLValueDesignator() const { return Designator;}
1354  bool isNullPointer() const { return IsNullPtr;}
1355 
1356  unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
1357  unsigned getLValueVersion() const { return Base.getVersion(); }
1358 
1359  void moveInto(APValue &V) const {
1360  if (Designator.Invalid)
1361  V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
1362  else {
1363  assert(!InvalidBase && "APValues can't handle invalid LValue bases");
1364  V = APValue(Base, Offset, Designator.Entries,
1365  Designator.IsOnePastTheEnd, IsNullPtr);
1366  }
1367  }
1368  void setFrom(ASTContext &Ctx, const APValue &V) {
1369  assert(V.isLValue() && "Setting LValue from a non-LValue?");
1370  Base = V.getLValueBase();
1371  Offset = V.getLValueOffset();
1372  InvalidBase = false;
1373  Designator = SubobjectDesignator(Ctx, V);
1374  IsNullPtr = V.isNullPointer();
1375  }
1376 
1377  void set(APValue::LValueBase B, bool BInvalid = false) {
1378 #ifndef NDEBUG
1379  // We only allow a few types of invalid bases. Enforce that here.
1380  if (BInvalid) {
1381  const auto *E = B.get<const Expr *>();
1382  assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
1383  "Unexpected type of invalid base");
1384  }
1385 #endif
1386 
1387  Base = B;
1388  Offset = CharUnits::fromQuantity(0);
1389  InvalidBase = BInvalid;
1390  Designator = SubobjectDesignator(getType(B));
1391  IsNullPtr = false;
1392  }
1393 
1394  void setNull(QualType PointerTy, uint64_t TargetVal) {
1395  Base = (Expr *)nullptr;
1396  Offset = CharUnits::fromQuantity(TargetVal);
1397  InvalidBase = false;
1398  Designator = SubobjectDesignator(PointerTy->getPointeeType());
1399  IsNullPtr = true;
1400  }
1401 
1402  void setInvalid(APValue::LValueBase B, unsigned I = 0) {
1403  set(B, true);
1404  }
1405 
1406  private:
1407  // Check that this LValue is not based on a null pointer. If it is, produce
1408  // a diagnostic and mark the designator as invalid.
1409  template <typename GenDiagType>
1410  bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) {
1411  if (Designator.Invalid)
1412  return false;
1413  if (IsNullPtr) {
1414  GenDiag();
1415  Designator.setInvalid();
1416  return false;
1417  }
1418  return true;
1419  }
1420 
1421  public:
1422  bool checkNullPointer(EvalInfo &Info, const Expr *E,
1423  CheckSubobjectKind CSK) {
1424  return checkNullPointerDiagnosingWith([&Info, E, CSK] {
1425  Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK;
1426  });
1427  }
1428 
1429  bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E,
1430  AccessKinds AK) {
1431  return checkNullPointerDiagnosingWith([&Info, E, AK] {
1432  Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
1433  });
1434  }
1435 
1436  // Check this LValue refers to an object. If not, set the designator to be
1437  // invalid and emit a diagnostic.
1438  bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
1439  return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
1440  Designator.checkSubobject(Info, E, CSK);
1441  }
1442 
1443  void addDecl(EvalInfo &Info, const Expr *E,
1444  const Decl *D, bool Virtual = false) {
1445  if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
1446  Designator.addDeclUnchecked(D, Virtual);
1447  }
1448  void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
1449  if (!Designator.Entries.empty()) {
1450  Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
1451  Designator.setInvalid();
1452  return;
1453  }
1454  if (checkSubobject(Info, E, CSK_ArrayToPointer)) {
1455  assert(getType(Base)->isPointerType() || getType(Base)->isArrayType());
1456  Designator.FirstEntryIsAnUnsizedArray = true;
1457  Designator.addUnsizedArrayUnchecked(ElemTy);
1458  }
1459  }
1460  void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
1461  if (checkSubobject(Info, E, CSK_ArrayToPointer))
1462  Designator.addArrayUnchecked(CAT);
1463  }
1464  void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
1465  if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
1466  Designator.addComplexUnchecked(EltTy, Imag);
1467  }
1468  void clearIsNullPointer() {
1469  IsNullPtr = false;
1470  }
1471  void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
1472  const APSInt &Index, CharUnits ElementSize) {
1473  // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
1474  // but we're not required to diagnose it and it's valid in C++.)
1475  if (!Index)
1476  return;
1477 
1478  // Compute the new offset in the appropriate width, wrapping at 64 bits.
1479  // FIXME: When compiling for a 32-bit target, we should use 32-bit
1480  // offsets.
1481  uint64_t Offset64 = Offset.getQuantity();
1482  uint64_t ElemSize64 = ElementSize.getQuantity();
1483  uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
1484  Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);
1485 
1486  if (checkNullPointer(Info, E, CSK_ArrayIndex))
1487  Designator.adjustIndex(Info, E, Index);
1488  clearIsNullPointer();
1489  }
1490  void adjustOffset(CharUnits N) {
1491  Offset += N;
1492  if (N.getQuantity())
1493  clearIsNullPointer();
1494  }
1495  };
1496 
1497  struct MemberPtr {
1498  MemberPtr() {}
1499  explicit MemberPtr(const ValueDecl *Decl) :
1500  DeclAndIsDerivedMember(Decl, false), Path() {}
1501 
1502  /// The member or (direct or indirect) field referred to by this member
1503  /// pointer, or 0 if this is a null member pointer.
1504  const ValueDecl *getDecl() const {
1505  return DeclAndIsDerivedMember.getPointer();
1506  }
1507  /// Is this actually a member of some type derived from the relevant class?
1508  bool isDerivedMember() const {
1509  return DeclAndIsDerivedMember.getInt();
1510  }
1511  /// Get the class which the declaration actually lives in.
1512  const CXXRecordDecl *getContainingRecord() const {
1513  return cast<CXXRecordDecl>(
1514  DeclAndIsDerivedMember.getPointer()->getDeclContext());
1515  }
1516 
1517  void moveInto(APValue &V) const {
1518  V = APValue(getDecl(), isDerivedMember(), Path);
1519  }
1520  void setFrom(const APValue &V) {
1521  assert(V.isMemberPointer());
1522  DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
1523  DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
1524  Path.clear();
1526  Path.insert(Path.end(), P.begin(), P.end());
1527  }
1528 
1529  /// DeclAndIsDerivedMember - The member declaration, and a flag indicating
1530  /// whether the member is a member of some class derived from the class type
1531  /// of the member pointer.
1532  llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
1533  /// Path - The path of base/derived classes from the member declaration's
1534  /// class (exclusive) to the class type of the member pointer (inclusive).
1536 
1537  /// Perform a cast towards the class of the Decl (either up or down the
1538  /// hierarchy).
1539  bool castBack(const CXXRecordDecl *Class) {
1540  assert(!Path.empty());
1541  const CXXRecordDecl *Expected;
1542  if (Path.size() >= 2)
1543  Expected = Path[Path.size() - 2];
1544  else
1545  Expected = getContainingRecord();
1546  if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
1547  // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
1548  // if B does not contain the original member and is not a base or
1549  // derived class of the class containing the original member, the result
1550  // of the cast is undefined.
1551  // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
1552  // (D::*). We consider that to be a language defect.
1553  return false;
1554  }
1555  Path.pop_back();
1556  return true;
1557  }
1558  /// Perform a base-to-derived member pointer cast.
1559  bool castToDerived(const CXXRecordDecl *Derived) {
1560  if (!getDecl())
1561  return true;
1562  if (!isDerivedMember()) {
1563  Path.push_back(Derived);
1564  return true;
1565  }
1566  if (!castBack(Derived))
1567  return false;
1568  if (Path.empty())
1569  DeclAndIsDerivedMember.setInt(false);
1570  return true;
1571  }
1572  /// Perform a derived-to-base member pointer cast.
1573  bool castToBase(const CXXRecordDecl *Base) {
1574  if (!getDecl())
1575  return true;
1576  if (Path.empty())
1577  DeclAndIsDerivedMember.setInt(true);
1578  if (isDerivedMember()) {
1579  Path.push_back(Base);
1580  return true;
1581  }
1582  return castBack(Base);
1583  }
1584  };
1585 
1586  /// Compare two member pointers, which are assumed to be of the same type.
1587  static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
1588  if (!LHS.getDecl() || !RHS.getDecl())
1589  return !LHS.getDecl() && !RHS.getDecl();
1590  if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
1591  return false;
1592  return LHS.Path == RHS.Path;
1593  }
1594 }
1595 
1596 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
1597 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
1598  const LValue &This, const Expr *E,
1599  bool AllowNonLiteralTypes = false);
1600 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
1601  bool InvalidBaseOK = false);
1602 static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
1603  bool InvalidBaseOK = false);
1604 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
1605  EvalInfo &Info);
1606 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
1607 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
1608 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
1609  EvalInfo &Info);
1610 static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
1611 static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
1612 static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
1613  EvalInfo &Info);
1614 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
1615 
1616 //===----------------------------------------------------------------------===//
1617 // Misc utilities
1618 //===----------------------------------------------------------------------===//
1619 
1620 /// A helper function to create a temporary and set an LValue.
1621 template <class KeyTy>
1622 static APValue &createTemporary(const KeyTy *Key, bool IsLifetimeExtended,
1623  LValue &LV, CallStackFrame &Frame) {
1624  LV.set({Key, Frame.Info.CurrentCall->Index,
1625  Frame.Info.CurrentCall->getTempVersion()});
1626  return Frame.createTemporary(Key, IsLifetimeExtended);
1627 }
1628 
1629 /// Negate an APSInt in place, converting it to a signed form if necessary, and
1630 /// preserving its value (by extending by up to one bit as needed).
1631 static void negateAsSigned(APSInt &Int) {
1632  if (Int.isUnsigned() || Int.isMinSignedValue()) {
1633  Int = Int.extend(Int.getBitWidth() + 1);
1634  Int.setIsSigned(true);
1635  }
1636  Int = -Int;
1637 }
1638 
1639 /// Produce a string describing the given constexpr call.
1640 static void describeCall(CallStackFrame *Frame, raw_ostream &Out) {
1641  unsigned ArgIndex = 0;
1642  bool IsMemberCall = isa<CXXMethodDecl>(Frame->Callee) &&
1643  !isa<CXXConstructorDecl>(Frame->Callee) &&
1644  cast<CXXMethodDecl>(Frame->Callee)->isInstance();
1645 
1646  if (!IsMemberCall)
1647  Out << *Frame->Callee << '(';
1648 
1649  if (Frame->This && IsMemberCall) {
1650  APValue Val;
1651  Frame->This->moveInto(Val);
1652  Val.printPretty(Out, Frame->Info.Ctx,
1653  Frame->This->Designator.MostDerivedType);
1654  // FIXME: Add parens around Val if needed.
1655  Out << "->" << *Frame->Callee << '(';
1656  IsMemberCall = false;
1657  }
1658 
1659  for (FunctionDecl::param_const_iterator I = Frame->Callee->param_begin(),
1660  E = Frame->Callee->param_end(); I != E; ++I, ++ArgIndex) {
1661  if (ArgIndex > (unsigned)IsMemberCall)
1662  Out << ", ";
1663 
1664  const ParmVarDecl *Param = *I;
1665  const APValue &Arg = Frame->Arguments[ArgIndex];
1666  Arg.printPretty(Out, Frame->Info.Ctx, Param->getType());
1667 
1668  if (ArgIndex == 0 && IsMemberCall)
1669  Out << "->" << *Frame->Callee << '(';
1670  }
1671 
1672  Out << ')';
1673 }
1674 
1675 /// Evaluate an expression to see if it had side-effects, and discard its
1676 /// result.
1677 /// \return \c true if the caller should keep evaluating.
1678 static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
1679  APValue Scratch;
1680  if (!Evaluate(Scratch, Info, E))
1681  // We don't need the value, but we might have skipped a side effect here.
1682  return Info.noteSideEffect();
1683  return true;
1684 }
1685 
1686 /// Should this call expression be treated as a string literal?
1687 static bool IsStringLiteralCall(const CallExpr *E) {
1688  unsigned Builtin = E->getBuiltinCallee();
1689  return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
1690  Builtin == Builtin::BI__builtin___NSStringMakeConstantString);
1691 }
1692 
1694  // C++11 [expr.const]p3 An address constant expression is a prvalue core
1695  // constant expression of pointer type that evaluates to...
1696 
1697  // ... a null pointer value, or a prvalue core constant expression of type
1698  // std::nullptr_t.
1699  if (!B) return true;
1700 
1701  if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
1702  // ... the address of an object with static storage duration,
1703  if (const VarDecl *VD = dyn_cast<VarDecl>(D))
1704  return VD->hasGlobalStorage();
1705  // ... the address of a function,
1706  return isa<FunctionDecl>(D);
1707  }
1708 
1709  const Expr *E = B.get<const Expr*>();
1710  switch (E->getStmtClass()) {
1711  default:
1712  return false;
1713  case Expr::CompoundLiteralExprClass: {
1714  const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
1715  return CLE->isFileScope() && CLE->isLValue();
1716  }
1717  case Expr::MaterializeTemporaryExprClass:
1718  // A materialized temporary might have been lifetime-extended to static
1719  // storage duration.
1720  return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
1721  // A string literal has static storage duration.
1722  case Expr::StringLiteralClass:
1723  case Expr::PredefinedExprClass:
1724  case Expr::ObjCStringLiteralClass:
1725  case Expr::ObjCEncodeExprClass:
1726  case Expr::CXXTypeidExprClass:
1727  case Expr::CXXUuidofExprClass:
1728  return true;
1729  case Expr::CallExprClass:
1730  return IsStringLiteralCall(cast<CallExpr>(E));
1731  // For GCC compatibility, &&label has static storage duration.
1732  case Expr::AddrLabelExprClass:
1733  return true;
1734  // A Block literal expression may be used as the initialization value for
1735  // Block variables at global or local static scope.
1736  case Expr::BlockExprClass:
1737  return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
1738  case Expr::ImplicitValueInitExprClass:
1739  // FIXME:
1740  // We can never form an lvalue with an implicit value initialization as its
1741  // base through expression evaluation, so these only appear in one case: the
1742  // implicit variable declaration we invent when checking whether a constexpr
1743  // constructor can produce a constant expression. We must assume that such
1744  // an expression might be a global lvalue.
1745  return true;
1746  }
1747 }
1748 
1749 static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
1750  return LVal.Base.dyn_cast<const ValueDecl*>();
1751 }
1752 
1753 static bool IsLiteralLValue(const LValue &Value) {
1754  if (Value.getLValueCallIndex())
1755  return false;
1756  const Expr *E = Value.Base.dyn_cast<const Expr*>();
1757  return E && !isa<MaterializeTemporaryExpr>(E);
1758 }
1759 
1760 static bool IsWeakLValue(const LValue &Value) {
1761  const ValueDecl *Decl = GetLValueBaseDecl(Value);
1762  return Decl && Decl->isWeak();
1763 }
1764 
1765 static bool isZeroSized(const LValue &Value) {
1766  const ValueDecl *Decl = GetLValueBaseDecl(Value);
1767  if (Decl && isa<VarDecl>(Decl)) {
1768  QualType Ty = Decl->getType();
1769  if (Ty->isArrayType())
1770  return Ty->isIncompleteType() ||
1771  Decl->getASTContext().getTypeSize(Ty) == 0;
1772  }
1773  return false;
1774 }
1775 
1776 static bool HasSameBase(const LValue &A, const LValue &B) {
1777  if (!A.getLValueBase())
1778  return !B.getLValueBase();
1779  if (!B.getLValueBase())
1780  return false;
1781 
1782  if (A.getLValueBase().getOpaqueValue() !=
1783  B.getLValueBase().getOpaqueValue()) {
1784  const Decl *ADecl = GetLValueBaseDecl(A);
1785  if (!ADecl)
1786  return false;
1787  const Decl *BDecl = GetLValueBaseDecl(B);
1788  if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl())
1789  return false;
1790  }
1791 
1792  return IsGlobalLValue(A.getLValueBase()) ||
1793  (A.getLValueCallIndex() == B.getLValueCallIndex() &&
1794  A.getLValueVersion() == B.getLValueVersion());
1795 }
1796 
1797 static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
1798  assert(Base && "no location for a null lvalue");
1799  const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
1800  if (VD)
1801  Info.Note(VD->getLocation(), diag::note_declared_at);
1802  else
1803  Info.Note(Base.get<const Expr*>()->getExprLoc(),
1804  diag::note_constexpr_temporary_here);
1805 }
1806 
1807 /// Check that this reference or pointer core constant expression is a valid
1808 /// value for an address or reference constant expression. Return true if we
1809 /// can fold this expression, whether or not it's a constant expression.
1810 static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
1811  QualType Type, const LValue &LVal,
1812  Expr::ConstExprUsage Usage) {
1813  bool IsReferenceType = Type->isReferenceType();
1814 
1815  APValue::LValueBase Base = LVal.getLValueBase();
1816  const SubobjectDesignator &Designator = LVal.getLValueDesignator();
1817 
1818  // Check that the object is a global. Note that the fake 'this' object we
1819  // manufacture when checking potential constant expressions is conservatively
1820  // assumed to be global here.
1821  if (!IsGlobalLValue(Base)) {
1822  if (Info.getLangOpts().CPlusPlus11) {
1823  const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
1824  Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
1825  << IsReferenceType << !Designator.Entries.empty()
1826  << !!VD << VD;
1827  NoteLValueLocation(Info, Base);
1828  } else {
1829  Info.FFDiag(Loc);
1830  }
1831  // Don't allow references to temporaries to escape.
1832  return false;
1833  }
1834  assert((Info.checkingPotentialConstantExpression() ||
1835  LVal.getLValueCallIndex() == 0) &&
1836  "have call index for global lvalue");
1837 
1838  if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) {
1839  if (const VarDecl *Var = dyn_cast<const VarDecl>(VD)) {
1840  // Check if this is a thread-local variable.
1841  if (Var->getTLSKind())
1842  return false;
1843 
1844  // A dllimport variable never acts like a constant.
1845  if (Usage == Expr::EvaluateForCodeGen && Var->hasAttr<DLLImportAttr>())
1846  return false;
1847  }
1848  if (const auto *FD = dyn_cast<const FunctionDecl>(VD)) {
1849  // __declspec(dllimport) must be handled very carefully:
1850  // We must never initialize an expression with the thunk in C++.
1851  // Doing otherwise would allow the same id-expression to yield
1852  // different addresses for the same function in different translation
1853  // units. However, this means that we must dynamically initialize the
1854  // expression with the contents of the import address table at runtime.
1855  //
1856  // The C language has no notion of ODR; furthermore, it has no notion of
1857  // dynamic initialization. This means that we are permitted to
1858  // perform initialization with the address of the thunk.
1859  if (Info.getLangOpts().CPlusPlus && Usage == Expr::EvaluateForCodeGen &&
1860  FD->hasAttr<DLLImportAttr>())
1861  return false;
1862  }
1863  }
1864 
1865  // Allow address constant expressions to be past-the-end pointers. This is
1866  // an extension: the standard requires them to point to an object.
1867  if (!IsReferenceType)
1868  return true;
1869 
1870  // A reference constant expression must refer to an object.
1871  if (!Base) {
1872  // FIXME: diagnostic
1873  Info.CCEDiag(Loc);
1874  return true;
1875  }
1876 
1877  // Does this refer one past the end of some object?
1878  if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
1879  const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
1880  Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
1881  << !Designator.Entries.empty() << !!VD << VD;
1882  NoteLValueLocation(Info, Base);
1883  }
1884 
1885  return true;
1886 }
1887 
1888 /// Member pointers are constant expressions unless they point to a
1889 /// non-virtual dllimport member function.
1890 static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
1891  SourceLocation Loc,
1892  QualType Type,
1893  const APValue &Value,
1894  Expr::ConstExprUsage Usage) {
1895  const ValueDecl *Member = Value.getMemberPointerDecl();
1896  const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
1897  if (!FD)
1898  return true;
1899  return Usage == Expr::EvaluateForMangling || FD->isVirtual() ||
1900  !FD->hasAttr<DLLImportAttr>();
1901 }
1902 
1903 /// Check that this core constant expression is of literal type, and if not,
1904 /// produce an appropriate diagnostic.
1905 static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
1906  const LValue *This = nullptr) {
1907  if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx))
1908  return true;
1909 
1910  // C++1y: A constant initializer for an object o [...] may also invoke
1911  // constexpr constructors for o and its subobjects even if those objects
1912  // are of non-literal class types.
1913  //
1914  // C++11 missed this detail for aggregates, so classes like this:
1915  // struct foo_t { union { int i; volatile int j; } u; };
1916  // are not (obviously) initializable like so:
1917  // __attribute__((__require_constant_initialization__))
1918  // static const foo_t x = {{0}};
1919  // because "i" is a subobject with non-literal initialization (due to the
1920  // volatile member of the union). See:
1921  // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
1922  // Therefore, we use the C++1y behavior.
1923  if (This && Info.EvaluatingDecl == This->getLValueBase())
1924  return true;
1925 
1926  // Prvalue constant expressions must be of literal types.
1927  if (Info.getLangOpts().CPlusPlus11)
1928  Info.FFDiag(E, diag::note_constexpr_nonliteral)
1929  << E->getType();
1930  else
1931  Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
1932  return false;
1933 }
1934 
1935 /// Check that this core constant expression value is a valid value for a
1936 /// constant expression. If not, report an appropriate diagnostic. Does not
1937 /// check that the expression is of literal type.
1938 static bool
1939 CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, QualType Type,
1940  const APValue &Value,
1942  if (Value.isUninit()) {
1943  Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
1944  << true << Type;
1945  return false;
1946  }
1947 
1948  // We allow _Atomic(T) to be initialized from anything that T can be
1949  // initialized from.
1950  if (const AtomicType *AT = Type->getAs<AtomicType>())
1951  Type = AT->getValueType();
1952 
1953  // Core issue 1454: For a literal constant expression of array or class type,
1954  // each subobject of its value shall have been initialized by a constant
1955  // expression.
1956  if (Value.isArray()) {
1957  QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
1958  for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
1959  if (!CheckConstantExpression(Info, DiagLoc, EltTy,
1960  Value.getArrayInitializedElt(I), Usage))
1961  return false;
1962  }
1963  if (!Value.hasArrayFiller())
1964  return true;
1965  return CheckConstantExpression(Info, DiagLoc, EltTy, Value.getArrayFiller(),
1966  Usage);
1967  }
1968  if (Value.isUnion() && Value.getUnionField()) {
1969  return CheckConstantExpression(Info, DiagLoc,
1970  Value.getUnionField()->getType(),
1971  Value.getUnionValue(), Usage);
1972  }
1973  if (Value.isStruct()) {
1974  RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
1975  if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
1976  unsigned BaseIndex = 0;
1977  for (const CXXBaseSpecifier &BS : CD->bases()) {
1978  if (!CheckConstantExpression(Info, DiagLoc, BS.getType(),
1979  Value.getStructBase(BaseIndex), Usage))
1980  return false;
1981  ++BaseIndex;
1982  }
1983  }
1984  for (const auto *I : RD->fields()) {
1985  if (I->isUnnamedBitfield())
1986  continue;
1987 
1988  if (!CheckConstantExpression(Info, DiagLoc, I->getType(),
1989  Value.getStructField(I->getFieldIndex()),
1990  Usage))
1991  return false;
1992  }
1993  }
1994 
1995  if (Value.isLValue()) {
1996  LValue LVal;
1997  LVal.setFrom(Info.Ctx, Value);
1998  return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Usage);
1999  }
2000 
2001  if (Value.isMemberPointer())
2002  return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Usage);
2003 
2004  // Everything else is fine.
2005  return true;
2006 }
2007 
2008 static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
2009  // A null base expression indicates a null pointer. These are always
2010  // evaluatable, and they are false unless the offset is zero.
2011  if (!Value.getLValueBase()) {
2012  Result = !Value.getLValueOffset().isZero();
2013  return true;
2014  }
2015 
2016  // We have a non-null base. These are generally known to be true, but if it's
2017  // a weak declaration it can be null at runtime.
2018  Result = true;
2019  const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
2020  return !Decl || !Decl->isWeak();
2021 }
2022 
2023 static bool HandleConversionToBool(const APValue &Val, bool &Result) {
2024  switch (Val.getKind()) {
2026  return false;
2027  case APValue::Int:
2028  Result = Val.getInt().getBoolValue();
2029  return true;
2030  case APValue::Float:
2031  Result = !Val.getFloat().isZero();
2032  return true;
2033  case APValue::ComplexInt:
2034  Result = Val.getComplexIntReal().getBoolValue() ||
2035  Val.getComplexIntImag().getBoolValue();
2036  return true;
2037  case APValue::ComplexFloat:
2038  Result = !Val.getComplexFloatReal().isZero() ||
2039  !Val.getComplexFloatImag().isZero();
2040  return true;
2041  case APValue::LValue:
2042  return EvalPointerValueAsBool(Val, Result);
2044  Result = Val.getMemberPointerDecl();
2045  return true;
2046  case APValue::Vector:
2047  case APValue::Array:
2048  case APValue::Struct:
2049  case APValue::Union:
2051  return false;
2052  }
2053 
2054  llvm_unreachable("unknown APValue kind");
2055 }
2056 
2057 static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
2058  EvalInfo &Info) {
2059  assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition");
2060  APValue Val;
2061  if (!Evaluate(Val, Info, E))
2062  return false;
2063  return HandleConversionToBool(Val, Result);
2064 }
2065 
2066 template<typename T>
2067 static bool HandleOverflow(EvalInfo &Info, const Expr *E,
2068  const T &SrcValue, QualType DestType) {
2069  Info.CCEDiag(E, diag::note_constexpr_overflow)
2070  << SrcValue << DestType;
2071  return Info.noteUndefinedBehavior();
2072 }
2073 
2074 static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
2075  QualType SrcType, const APFloat &Value,
2076  QualType DestType, APSInt &Result) {
2077  unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2078  // Determine whether we are converting to unsigned or signed.
2079  bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
2080 
2081  Result = APSInt(DestWidth, !DestSigned);
2082  bool ignored;
2083  if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
2084  & APFloat::opInvalidOp)
2085  return HandleOverflow(Info, E, Value, DestType);
2086  return true;
2087 }
2088 
2089 static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
2090  QualType SrcType, QualType DestType,
2091  APFloat &Result) {
2092  APFloat Value = Result;
2093  bool ignored;
2094  if (Result.convert(Info.Ctx.getFloatTypeSemantics(DestType),
2095  APFloat::rmNearestTiesToEven, &ignored)
2096  & APFloat::opOverflow)
2097  return HandleOverflow(Info, E, Value, DestType);
2098  return true;
2099 }
2100 
2101 static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
2102  QualType DestType, QualType SrcType,
2103  const APSInt &Value) {
2104  unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
2105  // Figure out if this is a truncate, extend or noop cast.
2106  // If the input is signed, do a sign extend, noop, or truncate.
2107  APSInt Result = Value.extOrTrunc(DestWidth);
2108  Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
2109  if (DestType->isBooleanType())
2110  Result = Value.getBoolValue();
2111  return Result;
2112 }
2113 
2114 static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
2115  QualType SrcType, const APSInt &Value,
2116  QualType DestType, APFloat &Result) {
2117  Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
2118  if (Result.convertFromAPInt(Value, Value.isSigned(),
2119  APFloat::rmNearestTiesToEven)
2120  & APFloat::opOverflow)
2121  return HandleOverflow(Info, E, Value, DestType);
2122  return true;
2123 }
2124 
2125 static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
2126  APValue &Value, const FieldDecl *FD) {
2127  assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield");
2128 
2129  if (!Value.isInt()) {
2130  // Trying to store a pointer-cast-to-integer into a bitfield.
2131  // FIXME: In this case, we should provide the diagnostic for casting
2132  // a pointer to an integer.
2133  assert(Value.isLValue() && "integral value neither int nor lvalue?");
2134  Info.FFDiag(E);
2135  return false;
2136  }
2137 
2138  APSInt &Int = Value.getInt();
2139  unsigned OldBitWidth = Int.getBitWidth();
2140  unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
2141  if (NewBitWidth < OldBitWidth)
2142  Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
2143  return true;
2144 }
2145 
2146 static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
2147  llvm::APInt &Res) {
2148  APValue SVal;
2149  if (!Evaluate(SVal, Info, E))
2150  return false;
2151  if (SVal.isInt()) {
2152  Res = SVal.getInt();
2153  return true;
2154  }
2155  if (SVal.isFloat()) {
2156  Res = SVal.getFloat().bitcastToAPInt();
2157  return true;
2158  }
2159  if (SVal.isVector()) {
2160  QualType VecTy = E->getType();
2161  unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
2162  QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
2163  unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
2164  bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
2165  Res = llvm::APInt::getNullValue(VecSize);
2166  for (unsigned i = 0; i < SVal.getVectorLength(); i++) {
2167  APValue &Elt = SVal.getVectorElt(i);
2168  llvm::APInt EltAsInt;
2169  if (Elt.isInt()) {
2170  EltAsInt = Elt.getInt();
2171  } else if (Elt.isFloat()) {
2172  EltAsInt = Elt.getFloat().bitcastToAPInt();
2173  } else {
2174  // Don't try to handle vectors of anything other than int or float
2175  // (not sure if it's possible to hit this case).
2176  Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2177  return false;
2178  }
2179  unsigned BaseEltSize = EltAsInt.getBitWidth();
2180  if (BigEndian)
2181  Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
2182  else
2183  Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
2184  }
2185  return true;
2186  }
2187  // Give up if the input isn't an int, float, or vector. For example, we
2188  // reject "(v4i16)(intptr_t)&a".
2189  Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2190  return false;
2191 }
2192 
2193 /// Perform the given integer operation, which is known to need at most BitWidth
2194 /// bits, and check for overflow in the original type (if that type was not an
2195 /// unsigned type).
2196 template<typename Operation>
2197 static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
2198  const APSInt &LHS, const APSInt &RHS,
2199  unsigned BitWidth, Operation Op,
2200  APSInt &Result) {
2201  if (LHS.isUnsigned()) {
2202  Result = Op(LHS, RHS);
2203  return true;
2204  }
2205 
2206  APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
2207  Result = Value.trunc(LHS.getBitWidth());
2208  if (Result.extend(BitWidth) != Value) {
2209  if (Info.checkingForOverflow())
2210  Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
2211  diag::warn_integer_constant_overflow)
2212  << Result.toString(10) << E->getType();
2213  else
2214  return HandleOverflow(Info, E, Value, E->getType());
2215  }
2216  return true;
2217 }
2218 
2219 /// Perform the given binary integer operation.
2220 static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
2221  BinaryOperatorKind Opcode, APSInt RHS,
2222  APSInt &Result) {
2223  switch (Opcode) {
2224  default:
2225  Info.FFDiag(E);
2226  return false;
2227  case BO_Mul:
2228  return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
2229  std::multiplies<APSInt>(), Result);
2230  case BO_Add:
2231  return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2232  std::plus<APSInt>(), Result);
2233  case BO_Sub:
2234  return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2235  std::minus<APSInt>(), Result);
2236  case BO_And: Result = LHS & RHS; return true;
2237  case BO_Xor: Result = LHS ^ RHS; return true;
2238  case BO_Or: Result = LHS | RHS; return true;
2239  case BO_Div:
2240  case BO_Rem:
2241  if (RHS == 0) {
2242  Info.FFDiag(E, diag::note_expr_divide_by_zero);
2243  return false;
2244  }
2245  Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
2246  // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
2247  // this operation and gives the two's complement result.
2248  if (RHS.isNegative() && RHS.isAllOnesValue() &&
2249  LHS.isSigned() && LHS.isMinSignedValue())
2250  return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1),
2251  E->getType());
2252  return true;
2253  case BO_Shl: {
2254  if (Info.getLangOpts().OpenCL)
2255  // OpenCL 6.3j: shift values are effectively % word size of LHS.
2256  RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2257  static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2258  RHS.isUnsigned());
2259  else if (RHS.isSigned() && RHS.isNegative()) {
2260  // During constant-folding, a negative shift is an opposite shift. Such
2261  // a shift is not a constant expression.
2262  Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2263  RHS = -RHS;
2264  goto shift_right;
2265  }
2266  shift_left:
2267  // C++11 [expr.shift]p1: Shift width must be less than the bit width of
2268  // the shifted type.
2269  unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2270  if (SA != RHS) {
2271  Info.CCEDiag(E, diag::note_constexpr_large_shift)
2272  << RHS << E->getType() << LHS.getBitWidth();
2273  } else if (LHS.isSigned()) {
2274  // C++11 [expr.shift]p2: A signed left shift must have a non-negative
2275  // operand, and must not overflow the corresponding unsigned type.
2276  if (LHS.isNegative())
2277  Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
2278  else if (LHS.countLeadingZeros() < SA)
2279  Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
2280  }
2281  Result = LHS << SA;
2282  return true;
2283  }
2284  case BO_Shr: {
2285  if (Info.getLangOpts().OpenCL)
2286  // OpenCL 6.3j: shift values are effectively % word size of LHS.
2287  RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2288  static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2289  RHS.isUnsigned());
2290  else if (RHS.isSigned() && RHS.isNegative()) {
2291  // During constant-folding, a negative shift is an opposite shift. Such a
2292  // shift is not a constant expression.
2293  Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2294  RHS = -RHS;
2295  goto shift_left;
2296  }
2297  shift_right:
2298  // C++11 [expr.shift]p1: Shift width must be less than the bit width of the
2299  // shifted type.
2300  unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
2301  if (SA != RHS)
2302  Info.CCEDiag(E, diag::note_constexpr_large_shift)
2303  << RHS << E->getType() << LHS.getBitWidth();
2304  Result = LHS >> SA;
2305  return true;
2306  }
2307 
2308  case BO_LT: Result = LHS < RHS; return true;
2309  case BO_GT: Result = LHS > RHS; return true;
2310  case BO_LE: Result = LHS <= RHS; return true;
2311  case BO_GE: Result = LHS >= RHS; return true;
2312  case BO_EQ: Result = LHS == RHS; return true;
2313  case BO_NE: Result = LHS != RHS; return true;
2314  case BO_Cmp:
2315  llvm_unreachable("BO_Cmp should be handled elsewhere");
2316  }
2317 }
2318 
2319 /// Perform the given binary floating-point operation, in-place, on LHS.
2320 static bool handleFloatFloatBinOp(EvalInfo &Info, const Expr *E,
2321  APFloat &LHS, BinaryOperatorKind Opcode,
2322  const APFloat &RHS) {
2323  switch (Opcode) {
2324  default:
2325  Info.FFDiag(E);
2326  return false;
2327  case BO_Mul:
2328  LHS.multiply(RHS, APFloat::rmNearestTiesToEven);
2329  break;
2330  case BO_Add:
2331  LHS.add(RHS, APFloat::rmNearestTiesToEven);
2332  break;
2333  case BO_Sub:
2334  LHS.subtract(RHS, APFloat::rmNearestTiesToEven);
2335  break;
2336  case BO_Div:
2337  LHS.divide(RHS, APFloat::rmNearestTiesToEven);
2338  break;
2339  }
2340 
2341  if (LHS.isInfinity() || LHS.isNaN()) {
2342  Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
2343  return Info.noteUndefinedBehavior();
2344  }
2345  return true;
2346 }
2347 
2348 /// Cast an lvalue referring to a base subobject to a derived class, by
2349 /// truncating the lvalue's path to the given length.
2350 static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
2351  const RecordDecl *TruncatedType,
2352  unsigned TruncatedElements) {
2353  SubobjectDesignator &D = Result.Designator;
2354 
2355  // Check we actually point to a derived class object.
2356  if (TruncatedElements == D.Entries.size())
2357  return true;
2358  assert(TruncatedElements >= D.MostDerivedPathLength &&
2359  "not casting to a derived class");
2360  if (!Result.checkSubobject(Info, E, CSK_Derived))
2361  return false;
2362 
2363  // Truncate the path to the subobject, and remove any derived-to-base offsets.
2364  const RecordDecl *RD = TruncatedType;
2365  for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
2366  if (RD->isInvalidDecl()) return false;
2367  const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
2368  const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
2369  if (isVirtualBaseClass(D.Entries[I]))
2370  Result.Offset -= Layout.getVBaseClassOffset(Base);
2371  else
2372  Result.Offset -= Layout.getBaseClassOffset(Base);
2373  RD = Base;
2374  }
2375  D.Entries.resize(TruncatedElements);
2376  return true;
2377 }
2378 
2379 static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
2380  const CXXRecordDecl *Derived,
2381  const CXXRecordDecl *Base,
2382  const ASTRecordLayout *RL = nullptr) {
2383  if (!RL) {
2384  if (Derived->isInvalidDecl()) return false;
2385  RL = &Info.Ctx.getASTRecordLayout(Derived);
2386  }
2387 
2388  Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
2389  Obj.addDecl(Info, E, Base, /*Virtual*/ false);
2390  return true;
2391 }
2392 
2393 static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
2394  const CXXRecordDecl *DerivedDecl,
2395  const CXXBaseSpecifier *Base) {
2396  const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
2397 
2398  if (!Base->isVirtual())
2399  return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
2400 
2401  SubobjectDesignator &D = Obj.Designator;
2402  if (D.Invalid)
2403  return false;
2404 
2405  // Extract most-derived object and corresponding type.
2406  DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
2407  if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
2408  return false;
2409 
2410  // Find the virtual base class.
2411  if (DerivedDecl->isInvalidDecl()) return false;
2412  const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
2413  Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
2414  Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
2415  return true;
2416 }
2417 
2418 static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
2419  QualType Type, LValue &Result) {
2420  for (CastExpr::path_const_iterator PathI = E->path_begin(),
2421  PathE = E->path_end();
2422  PathI != PathE; ++PathI) {
2423  if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
2424  *PathI))
2425  return false;
2426  Type = (*PathI)->getType();
2427  }
2428  return true;
2429 }
2430 
2431 /// Update LVal to refer to the given field, which must be a member of the type
2432 /// currently described by LVal.
2433 static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
2434  const FieldDecl *FD,
2435  const ASTRecordLayout *RL = nullptr) {
2436  if (!RL) {
2437  if (FD->getParent()->isInvalidDecl()) return false;
2438  RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
2439  }
2440 
2441  unsigned I = FD->getFieldIndex();
2442  LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
2443  LVal.addDecl(Info, E, FD);
2444  return true;
2445 }
2446 
2447 /// Update LVal to refer to the given indirect field.
2448 static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
2449  LValue &LVal,
2450  const IndirectFieldDecl *IFD) {
2451  for (const auto *C : IFD->chain())
2452  if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
2453  return false;
2454  return true;
2455 }
2456 
2457 /// Get the size of the given type in char units.
2458 static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
2459  QualType Type, CharUnits &Size) {
2460  // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
2461  // extension.
2462  if (Type->isVoidType() || Type->isFunctionType()) {
2463  Size = CharUnits::One();
2464  return true;
2465  }
2466 
2467  if (Type->isDependentType()) {
2468  Info.FFDiag(Loc);
2469  return false;
2470  }
2471 
2472  if (!Type->isConstantSizeType()) {
2473  // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
2474  // FIXME: Better diagnostic.
2475  Info.FFDiag(Loc);
2476  return false;
2477  }
2478 
2479  Size = Info.Ctx.getTypeSizeInChars(Type);
2480  return true;
2481 }
2482 
2483 /// Update a pointer value to model pointer arithmetic.
2484 /// \param Info - Information about the ongoing evaluation.
2485 /// \param E - The expression being evaluated, for diagnostic purposes.
2486 /// \param LVal - The pointer value to be updated.
2487 /// \param EltTy - The pointee type represented by LVal.
2488 /// \param Adjustment - The adjustment, in objects of type EltTy, to add.
2489 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
2490  LValue &LVal, QualType EltTy,
2491  APSInt Adjustment) {
2492  CharUnits SizeOfPointee;
2493  if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
2494  return false;
2495 
2496  LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
2497  return true;
2498 }
2499 
2500 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
2501  LValue &LVal, QualType EltTy,
2502  int64_t Adjustment) {
2503  return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
2504  APSInt::get(Adjustment));
2505 }
2506 
2507 /// Update an lvalue to refer to a component of a complex number.
2508 /// \param Info - Information about the ongoing evaluation.
2509 /// \param LVal - The lvalue to be updated.
2510 /// \param EltTy - The complex number's component type.
2511 /// \param Imag - False for the real component, true for the imaginary.
2512 static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
2513  LValue &LVal, QualType EltTy,
2514  bool Imag) {
2515  if (Imag) {
2516  CharUnits SizeOfComponent;
2517  if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
2518  return false;
2519  LVal.Offset += SizeOfComponent;
2520  }
2521  LVal.addComplex(Info, E, EltTy, Imag);
2522  return true;
2523 }
2524 
2525 static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv,
2526  QualType Type, const LValue &LVal,
2527  APValue &RVal);
2528 
2529 /// Try to evaluate the initializer for a variable declaration.
2530 ///
2531 /// \param Info Information about the ongoing evaluation.
2532 /// \param E An expression to be used when printing diagnostics.
2533 /// \param VD The variable whose initializer should be obtained.
2534 /// \param Frame The frame in which the variable was created. Must be null
2535 /// if this variable is not local to the evaluation.
2536 /// \param Result Filled in with a pointer to the value of the variable.
2537 static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
2538  const VarDecl *VD, CallStackFrame *Frame,
2539  APValue *&Result, const LValue *LVal) {
2540 
2541  // If this is a parameter to an active constexpr function call, perform
2542  // argument substitution.
2543  if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) {
2544  // Assume arguments of a potential constant expression are unknown
2545  // constant expressions.
2546  if (Info.checkingPotentialConstantExpression())
2547  return false;
2548  if (!Frame || !Frame->Arguments) {
2549  Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2550  return false;
2551  }
2552  Result = &Frame->Arguments[PVD->getFunctionScopeIndex()];
2553  return true;
2554  }
2555 
2556  // If this is a local variable, dig out its value.
2557  if (Frame) {
2558  Result = LVal ? Frame->getTemporary(VD, LVal->getLValueVersion())
2559  : Frame->getCurrentTemporary(VD);
2560  if (!Result) {
2561  // Assume variables referenced within a lambda's call operator that were
2562  // not declared within the call operator are captures and during checking
2563  // of a potential constant expression, assume they are unknown constant
2564  // expressions.
2565  assert(isLambdaCallOperator(Frame->Callee) &&
2566  (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&
2567  "missing value for local variable");
2568  if (Info.checkingPotentialConstantExpression())
2569  return false;
2570  // FIXME: implement capture evaluation during constant expr evaluation.
2571  Info.FFDiag(E->getBeginLoc(),
2572  diag::note_unimplemented_constexpr_lambda_feature_ast)
2573  << "captures not currently allowed";
2574  return false;
2575  }
2576  return true;
2577  }
2578 
2579  // Dig out the initializer, and use the declaration which it's attached to.
2580  const Expr *Init = VD->getAnyInitializer(VD);
2581  if (!Init || Init->isValueDependent()) {
2582  // If we're checking a potential constant expression, the variable could be
2583  // initialized later.
2584  if (!Info.checkingPotentialConstantExpression())
2585  Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2586  return false;
2587  }
2588 
2589  // If we're currently evaluating the initializer of this declaration, use that
2590  // in-flight value.
2591  if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) {
2592  Result = Info.EvaluatingDeclValue;
2593  return true;
2594  }
2595 
2596  // Never evaluate the initializer of a weak variable. We can't be sure that
2597  // this is the definition which will be used.
2598  if (VD->isWeak()) {
2599  Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2600  return false;
2601  }
2602 
2603  // Check that we can fold the initializer. In C++, we will have already done
2604  // this in the cases where it matters for conformance.
2606  if (!VD->evaluateValue(Notes)) {
2607  Info.FFDiag(E, diag::note_constexpr_var_init_non_constant,
2608  Notes.size() + 1) << VD;
2609  Info.Note(VD->getLocation(), diag::note_declared_at);
2610  Info.addNotes(Notes);
2611  return false;
2612  } else if (!VD->checkInitIsICE()) {
2613  Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant,
2614  Notes.size() + 1) << VD;
2615  Info.Note(VD->getLocation(), diag::note_declared_at);
2616  Info.addNotes(Notes);
2617  }
2618 
2619  Result = VD->getEvaluatedValue();
2620  return true;
2621 }
2622 
2624  Qualifiers Quals = T.getQualifiers();
2625  return Quals.hasConst() && !Quals.hasVolatile();
2626 }
2627 
2628 /// Get the base index of the given base class within an APValue representing
2629 /// the given derived class.
2630 static unsigned getBaseIndex(const CXXRecordDecl *Derived,
2631  const CXXRecordDecl *Base) {
2632  Base = Base->getCanonicalDecl();
2633  unsigned Index = 0;
2635  E = Derived->bases_end(); I != E; ++I, ++Index) {
2636  if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
2637  return Index;
2638  }
2639 
2640  llvm_unreachable("base class missing from derived class's bases list");
2641 }
2642 
2643 /// Extract the value of a character from a string literal.
2644 static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
2645  uint64_t Index) {
2646  // FIXME: Support MakeStringConstant
2647  if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
2648  std::string Str;
2649  Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
2650  assert(Index <= Str.size() && "Index too large");
2651  return APSInt::getUnsigned(Str.c_str()[Index]);
2652  }
2653 
2654  if (auto PE = dyn_cast<PredefinedExpr>(Lit))
2655  Lit = PE->getFunctionName();
2656  const StringLiteral *S = cast<StringLiteral>(Lit);
2657  const ConstantArrayType *CAT =
2658  Info.Ctx.getAsConstantArrayType(S->getType());
2659  assert(CAT && "string literal isn't an array");
2660  QualType CharType = CAT->getElementType();
2661  assert(CharType->isIntegerType() && "unexpected character type");
2662 
2663  APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
2664  CharType->isUnsignedIntegerType());
2665  if (Index < S->getLength())
2666  Value = S->getCodeUnit(Index);
2667  return Value;
2668 }
2669 
2670 // Expand a string literal into an array of characters.
2671 static void expandStringLiteral(EvalInfo &Info, const Expr *Lit,
2672  APValue &Result) {
2673  const StringLiteral *S = cast<StringLiteral>(Lit);
2674  const ConstantArrayType *CAT =
2675  Info.Ctx.getAsConstantArrayType(S->getType());
2676  assert(CAT && "string literal isn't an array");
2677  QualType CharType = CAT->getElementType();
2678  assert(CharType->isIntegerType() && "unexpected character type");
2679 
2680  unsigned Elts = CAT->getSize().getZExtValue();
2681  Result = APValue(APValue::UninitArray(),
2682  std::min(S->getLength(), Elts), Elts);
2683  APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
2684  CharType->isUnsignedIntegerType());
2685  if (Result.hasArrayFiller())
2686  Result.getArrayFiller() = APValue(Value);
2687  for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
2688  Value = S->getCodeUnit(I);
2689  Result.getArrayInitializedElt(I) = APValue(Value);
2690  }
2691 }
2692 
2693 // Expand an array so that it has more than Index filled elements.
2694 static void expandArray(APValue &Array, unsigned Index) {
2695  unsigned Size = Array.getArraySize();
2696  assert(Index < Size);
2697 
2698  // Always at least double the number of elements for which we store a value.
2699  unsigned OldElts = Array.getArrayInitializedElts();
2700  unsigned NewElts = std::max(Index+1, OldElts * 2);
2701  NewElts = std::min(Size, std::max(NewElts, 8u));
2702 
2703  // Copy the data across.
2704  APValue NewValue(APValue::UninitArray(), NewElts, Size);
2705  for (unsigned I = 0; I != OldElts; ++I)
2706  NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
2707  for (unsigned I = OldElts; I != NewElts; ++I)
2708  NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
2709  if (NewValue.hasArrayFiller())
2710  NewValue.getArrayFiller() = Array.getArrayFiller();
2711  Array.swap(NewValue);
2712 }
2713 
2714 /// Determine whether a type would actually be read by an lvalue-to-rvalue
2715 /// conversion. If it's of class type, we may assume that the copy operation
2716 /// is trivial. Note that this is never true for a union type with fields
2717 /// (because the copy always "reads" the active member) and always true for
2718 /// a non-class type.
2721  if (!RD || (RD->isUnion() && !RD->field_empty()))
2722  return true;
2723  if (RD->isEmpty())
2724  return false;
2725 
2726  for (auto *Field : RD->fields())
2727  if (isReadByLvalueToRvalueConversion(Field->getType()))
2728  return true;
2729 
2730  for (auto &BaseSpec : RD->bases())
2731  if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
2732  return true;
2733 
2734  return false;
2735 }
2736 
2737 /// Diagnose an attempt to read from any unreadable field within the specified
2738 /// type, which might be a class type.
2739 static bool diagnoseUnreadableFields(EvalInfo &Info, const Expr *E,
2740  QualType T) {
2742  if (!RD)
2743  return false;
2744 
2745  if (!RD->hasMutableFields())
2746  return false;
2747 
2748  for (auto *Field : RD->fields()) {
2749  // If we're actually going to read this field in some way, then it can't
2750  // be mutable. If we're in a union, then assigning to a mutable field
2751  // (even an empty one) can change the active member, so that's not OK.
2752  // FIXME: Add core issue number for the union case.
2753  if (Field->isMutable() &&
2754  (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
2755  Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1) << Field;
2756  Info.Note(Field->getLocation(), diag::note_declared_at);
2757  return true;
2758  }
2759 
2760  if (diagnoseUnreadableFields(Info, E, Field->getType()))
2761  return true;
2762  }
2763 
2764  for (auto &BaseSpec : RD->bases())
2765  if (diagnoseUnreadableFields(Info, E, BaseSpec.getType()))
2766  return true;
2767 
2768  // All mutable fields were empty, and thus not actually read.
2769  return false;
2770 }
2771 
2772 namespace {
2773 /// A handle to a complete object (an object that is not a subobject of
2774 /// another object).
2775 struct CompleteObject {
2776  /// The value of the complete object.
2777  APValue *Value;
2778  /// The type of the complete object.
2779  QualType Type;
2780  bool LifetimeStartedInEvaluation;
2781 
2782  CompleteObject() : Value(nullptr) {}
2783  CompleteObject(APValue *Value, QualType Type,
2784  bool LifetimeStartedInEvaluation)
2785  : Value(Value), Type(Type),
2786  LifetimeStartedInEvaluation(LifetimeStartedInEvaluation) {
2787  assert(Value && "missing value for complete object");
2788  }
2789 
2790  explicit operator bool() const { return Value; }
2791 };
2792 } // end anonymous namespace
2793 
2794 /// Find the designated sub-object of an rvalue.
2795 template<typename SubobjectHandler>
2796 typename SubobjectHandler::result_type
2797 findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
2798  const SubobjectDesignator &Sub, SubobjectHandler &handler) {
2799  if (Sub.Invalid)
2800  // A diagnostic will have already been produced.
2801  return handler.failed();
2802  if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
2803  if (Info.getLangOpts().CPlusPlus11)
2804  Info.FFDiag(E, Sub.isOnePastTheEnd()
2805  ? diag::note_constexpr_access_past_end
2806  : diag::note_constexpr_access_unsized_array)
2807  << handler.AccessKind;
2808  else
2809  Info.FFDiag(E);
2810  return handler.failed();
2811  }
2812 
2813  APValue *O = Obj.Value;
2814  QualType ObjType = Obj.Type;
2815  const FieldDecl *LastField = nullptr;
2816  const bool MayReadMutableMembers =
2817  Obj.LifetimeStartedInEvaluation && Info.getLangOpts().CPlusPlus14;
2818 
2819  // Walk the designator's path to find the subobject.
2820  for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
2821  if (O->isUninit()) {
2822  if (!Info.checkingPotentialConstantExpression())
2823  Info.FFDiag(E, diag::note_constexpr_access_uninit) << handler.AccessKind;
2824  return handler.failed();
2825  }
2826 
2827  if (I == N) {
2828  // If we are reading an object of class type, there may still be more
2829  // things we need to check: if there are any mutable subobjects, we
2830  // cannot perform this read. (This only happens when performing a trivial
2831  // copy or assignment.)
2832  if (ObjType->isRecordType() && handler.AccessKind == AK_Read &&
2833  !MayReadMutableMembers && diagnoseUnreadableFields(Info, E, ObjType))
2834  return handler.failed();
2835 
2836  if (!handler.found(*O, ObjType))
2837  return false;
2838 
2839  // If we modified a bit-field, truncate it to the right width.
2840  if (handler.AccessKind != AK_Read &&
2841  LastField && LastField->isBitField() &&
2842  !truncateBitfieldValue(Info, E, *O, LastField))
2843  return false;
2844 
2845  return true;
2846  }
2847 
2848  LastField = nullptr;
2849  if (ObjType->isArrayType()) {
2850  // Next subobject is an array element.
2851  const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
2852  assert(CAT && "vla in literal type?");
2853  uint64_t Index = Sub.Entries[I].ArrayIndex;
2854  if (CAT->getSize().ule(Index)) {
2855  // Note, it should not be possible to form a pointer with a valid
2856  // designator which points more than one past the end of the array.
2857  if (Info.getLangOpts().CPlusPlus11)
2858  Info.FFDiag(E, diag::note_constexpr_access_past_end)
2859  << handler.AccessKind;
2860  else
2861  Info.FFDiag(E);
2862  return handler.failed();
2863  }
2864 
2865  ObjType = CAT->getElementType();
2866 
2867  // An array object is represented as either an Array APValue or as an
2868  // LValue which refers to a string literal.
2869  if (O->isLValue()) {
2870  assert(I == N - 1 && "extracting subobject of character?");
2871  assert(!O->hasLValuePath() || O->getLValuePath().empty());
2872  if (handler.AccessKind != AK_Read)
2873  expandStringLiteral(Info, O->getLValueBase().get<const Expr *>(),
2874  *O);
2875  else
2876  return handler.foundString(*O, ObjType, Index);
2877  }
2878 
2879  if (O->getArrayInitializedElts() > Index)
2880  O = &O->getArrayInitializedElt(Index);
2881  else if (handler.AccessKind != AK_Read) {
2882  expandArray(*O, Index);
2883  O = &O->getArrayInitializedElt(Index);
2884  } else
2885  O = &O->getArrayFiller();
2886  } else if (ObjType->isAnyComplexType()) {
2887  // Next subobject is a complex number.
2888  uint64_t Index = Sub.Entries[I].ArrayIndex;
2889  if (Index > 1) {
2890  if (Info.getLangOpts().CPlusPlus11)
2891  Info.FFDiag(E, diag::note_constexpr_access_past_end)
2892  << handler.AccessKind;
2893  else
2894  Info.FFDiag(E);
2895  return handler.failed();
2896  }
2897 
2898  bool WasConstQualified = ObjType.isConstQualified();
2899  ObjType = ObjType->castAs<ComplexType>()->getElementType();
2900  if (WasConstQualified)
2901  ObjType.addConst();
2902 
2903  assert(I == N - 1 && "extracting subobject of scalar?");
2904  if (O->isComplexInt()) {
2905  return handler.found(Index ? O->getComplexIntImag()
2906  : O->getComplexIntReal(), ObjType);
2907  } else {
2908  assert(O->isComplexFloat());
2909  return handler.found(Index ? O->getComplexFloatImag()
2910  : O->getComplexFloatReal(), ObjType);
2911  }
2912  } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
2913  // In C++14 onwards, it is permitted to read a mutable member whose
2914  // lifetime began within the evaluation.
2915  // FIXME: Should we also allow this in C++11?
2916  if (Field->isMutable() && handler.AccessKind == AK_Read &&
2917  !MayReadMutableMembers) {
2918  Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1)
2919  << Field;
2920  Info.Note(Field->getLocation(), diag::note_declared_at);
2921  return handler.failed();
2922  }
2923 
2924  // Next subobject is a class, struct or union field.
2925  RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
2926  if (RD->isUnion()) {
2927  const FieldDecl *UnionField = O->getUnionField();
2928  if (!UnionField ||
2929  UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
2930  Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
2931  << handler.AccessKind << Field << !UnionField << UnionField;
2932  return handler.failed();
2933  }
2934  O = &O->getUnionValue();
2935  } else
2936  O = &O->getStructField(Field->getFieldIndex());
2937 
2938  bool WasConstQualified = ObjType.isConstQualified();
2939  ObjType = Field->getType();
2940  if (WasConstQualified && !Field->isMutable())
2941  ObjType.addConst();
2942 
2943  if (ObjType.isVolatileQualified()) {
2944  if (Info.getLangOpts().CPlusPlus) {
2945  // FIXME: Include a description of the path to the volatile subobject.
2946  Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
2947  << handler.AccessKind << 2 << Field;
2948  Info.Note(Field->getLocation(), diag::note_declared_at);
2949  } else {
2950  Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2951  }
2952  return handler.failed();
2953  }
2954 
2955  LastField = Field;
2956  } else {
2957  // Next subobject is a base class.
2958  const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
2959  const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
2960  O = &O->getStructBase(getBaseIndex(Derived, Base));
2961 
2962  bool WasConstQualified = ObjType.isConstQualified();
2963  ObjType = Info.Ctx.getRecordType(Base);
2964  if (WasConstQualified)
2965  ObjType.addConst();
2966  }
2967  }
2968 }
2969 
2970 namespace {
2971 struct ExtractSubobjectHandler {
2972  EvalInfo &Info;
2973  APValue &Result;
2974 
2975  static const AccessKinds AccessKind = AK_Read;
2976 
2977  typedef bool result_type;
2978  bool failed() { return false; }
2979  bool found(APValue &Subobj, QualType SubobjType) {
2980  Result = Subobj;
2981  return true;
2982  }
2983  bool found(APSInt &Value, QualType SubobjType) {
2984  Result = APValue(Value);
2985  return true;
2986  }
2987  bool found(APFloat &Value, QualType SubobjType) {
2988  Result = APValue(Value);
2989  return true;
2990  }
2991  bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
2993  Info, Subobj.getLValueBase().get<const Expr *>(), Character));
2994  return true;
2995  }
2996 };
2997 } // end anonymous namespace
2998 
3000 
3001 /// Extract the designated sub-object of an rvalue.
3002 static bool extractSubobject(EvalInfo &Info, const Expr *E,
3003  const CompleteObject &Obj,
3004  const SubobjectDesignator &Sub,
3005  APValue &Result) {
3006  ExtractSubobjectHandler Handler = { Info, Result };
3007  return findSubobject(Info, E, Obj, Sub, Handler);
3008 }
3009 
3010 namespace {
3011 struct ModifySubobjectHandler {
3012  EvalInfo &Info;
3013  APValue &NewVal;
3014  const Expr *E;
3015 
3016  typedef bool result_type;
3017  static const AccessKinds AccessKind = AK_Assign;
3018 
3019  bool checkConst(QualType QT) {
3020  // Assigning to a const object has undefined behavior.
3021  if (QT.isConstQualified()) {
3022  Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3023  return false;
3024  }
3025  return true;
3026  }
3027 
3028  bool failed() { return false; }
3029  bool found(APValue &Subobj, QualType SubobjType) {
3030  if (!checkConst(SubobjType))
3031  return false;
3032  // We've been given ownership of NewVal, so just swap it in.
3033  Subobj.swap(NewVal);
3034  return true;
3035  }
3036  bool found(APSInt &Value, QualType SubobjType) {
3037  if (!checkConst(SubobjType))
3038  return false;
3039  if (!NewVal.isInt()) {
3040  // Maybe trying to write a cast pointer value into a complex?
3041  Info.FFDiag(E);
3042  return false;
3043  }
3044  Value = NewVal.getInt();
3045  return true;
3046  }
3047  bool found(APFloat &Value, QualType SubobjType) {
3048  if (!checkConst(SubobjType))
3049  return false;
3050  Value = NewVal.getFloat();
3051  return true;
3052  }
3053  bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
3054  llvm_unreachable("shouldn't encounter string elements with ExpandArrays");
3055  }
3056 };
3057 } // end anonymous namespace
3058 
3060 
3061 /// Update the designated sub-object of an rvalue to the given value.
3062 static bool modifySubobject(EvalInfo &Info, const Expr *E,
3063  const CompleteObject &Obj,
3064  const SubobjectDesignator &Sub,
3065  APValue &NewVal) {
3066  ModifySubobjectHandler Handler = { Info, NewVal, E };
3067  return findSubobject(Info, E, Obj, Sub, Handler);
3068 }
3069 
3070 /// Find the position where two subobject designators diverge, or equivalently
3071 /// the length of the common initial subsequence.
3072 static unsigned FindDesignatorMismatch(QualType ObjType,
3073  const SubobjectDesignator &A,
3074  const SubobjectDesignator &B,
3075  bool &WasArrayIndex) {
3076  unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
3077  for (/**/; I != N; ++I) {
3078  if (!ObjType.isNull() &&
3079  (ObjType->isArrayType() || ObjType->isAnyComplexType())) {
3080  // Next subobject is an array element.
3081  if (A.Entries[I].ArrayIndex != B.Entries[I].ArrayIndex) {
3082  WasArrayIndex = true;
3083  return I;
3084  }
3085  if (ObjType->isAnyComplexType())
3086  ObjType = ObjType->castAs<ComplexType>()->getElementType();
3087  else
3088  ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
3089  } else {
3090  if (A.Entries[I].BaseOrMember != B.Entries[I].BaseOrMember) {
3091  WasArrayIndex = false;
3092  return I;
3093  }
3094  if (const FieldDecl *FD = getAsField(A.Entries[I]))
3095  // Next subobject is a field.
3096  ObjType = FD->getType();
3097  else
3098  // Next subobject is a base class.
3099  ObjType = QualType();
3100  }
3101  }
3102  WasArrayIndex = false;
3103  return I;
3104 }
3105 
3106 /// Determine whether the given subobject designators refer to elements of the
3107 /// same array object.
3108 static bool AreElementsOfSameArray(QualType ObjType,
3109  const SubobjectDesignator &A,
3110  const SubobjectDesignator &B) {
3111  if (A.Entries.size() != B.Entries.size())
3112  return false;
3113 
3114  bool IsArray = A.MostDerivedIsArrayElement;
3115  if (IsArray && A.MostDerivedPathLength != A.Entries.size())
3116  // A is a subobject of the array element.
3117  return false;
3118 
3119  // If A (and B) designates an array element, the last entry will be the array
3120  // index. That doesn't have to match. Otherwise, we're in the 'implicit array
3121  // of length 1' case, and the entire path must match.
3122  bool WasArrayIndex;
3123  unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
3124  return CommonLength >= A.Entries.size() - IsArray;
3125 }
3126 
3127 /// Find the complete object to which an LValue refers.
3128 static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
3129  AccessKinds AK, const LValue &LVal,
3130  QualType LValType) {
3131  if (!LVal.Base) {
3132  Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
3133  return CompleteObject();
3134  }
3135 
3136  CallStackFrame *Frame = nullptr;
3137  if (LVal.getLValueCallIndex()) {
3138  Frame = Info.getCallFrame(LVal.getLValueCallIndex());
3139  if (!Frame) {
3140  Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
3141  << AK << LVal.Base.is<const ValueDecl*>();
3142  NoteLValueLocation(Info, LVal.Base);
3143  return CompleteObject();
3144  }
3145  }
3146 
3147  // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
3148  // is not a constant expression (even if the object is non-volatile). We also
3149  // apply this rule to C++98, in order to conform to the expected 'volatile'
3150  // semantics.
3151  if (LValType.isVolatileQualified()) {
3152  if (Info.getLangOpts().CPlusPlus)
3153  Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
3154  << AK << LValType;
3155  else
3156  Info.FFDiag(E);
3157  return CompleteObject();
3158  }
3159 
3160  // Compute value storage location and type of base object.
3161  APValue *BaseVal = nullptr;
3162  QualType BaseType = getType(LVal.Base);
3163  bool LifetimeStartedInEvaluation = Frame;
3164 
3165  if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl*>()) {
3166  // In C++98, const, non-volatile integers initialized with ICEs are ICEs.
3167  // In C++11, constexpr, non-volatile variables initialized with constant
3168  // expressions are constant expressions too. Inside constexpr functions,
3169  // parameters are constant expressions even if they're non-const.
3170  // In C++1y, objects local to a constant expression (those with a Frame) are
3171  // both readable and writable inside constant expressions.
3172  // In C, such things can also be folded, although they are not ICEs.
3173  const VarDecl *VD = dyn_cast<VarDecl>(D);
3174  if (VD) {
3175  if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
3176  VD = VDef;
3177  }
3178  if (!VD || VD->isInvalidDecl()) {
3179  Info.FFDiag(E);
3180  return CompleteObject();
3181  }
3182 
3183  // Accesses of volatile-qualified objects are not allowed.
3184  if (BaseType.isVolatileQualified()) {
3185  if (Info.getLangOpts().CPlusPlus) {
3186  Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3187  << AK << 1 << VD;
3188  Info.Note(VD->getLocation(), diag::note_declared_at);
3189  } else {
3190  Info.FFDiag(E);
3191  }
3192  return CompleteObject();
3193  }
3194 
3195  // Unless we're looking at a local variable or argument in a constexpr call,
3196  // the variable we're reading must be const.
3197  if (!Frame) {
3198  if (Info.getLangOpts().CPlusPlus14 &&
3199  VD == Info.EvaluatingDecl.dyn_cast<const ValueDecl *>()) {
3200  // OK, we can read and modify an object if we're in the process of
3201  // evaluating its initializer, because its lifetime began in this
3202  // evaluation.
3203  } else if (AK != AK_Read) {
3204  // All the remaining cases only permit reading.
3205  Info.FFDiag(E, diag::note_constexpr_modify_global);
3206  return CompleteObject();
3207  } else if (VD->isConstexpr()) {
3208  // OK, we can read this variable.
3209  } else if (BaseType->isIntegralOrEnumerationType()) {
3210  // In OpenCL if a variable is in constant address space it is a const value.
3211  if (!(BaseType.isConstQualified() ||
3212  (Info.getLangOpts().OpenCL &&
3213  BaseType.getAddressSpace() == LangAS::opencl_constant))) {
3214  if (Info.getLangOpts().CPlusPlus) {
3215  Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
3216  Info.Note(VD->getLocation(), diag::note_declared_at);
3217  } else {
3218  Info.FFDiag(E);
3219  }
3220  return CompleteObject();
3221  }
3222  } else if (BaseType->isFloatingType() && BaseType.isConstQualified()) {
3223  // We support folding of const floating-point types, in order to make
3224  // static const data members of such types (supported as an extension)
3225  // more useful.
3226  if (Info.getLangOpts().CPlusPlus11) {
3227  Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD;
3228  Info.Note(VD->getLocation(), diag::note_declared_at);
3229  } else {
3230  Info.CCEDiag(E);
3231  }
3232  } else if (BaseType.isConstQualified() && VD->hasDefinition(Info.Ctx)) {
3233  Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr) << VD;
3234  // Keep evaluating to see what we can do.
3235  } else {
3236  // FIXME: Allow folding of values of any literal type in all languages.
3237  if (Info.checkingPotentialConstantExpression() &&
3238  VD->getType().isConstQualified() && !VD->hasDefinition(Info.Ctx)) {
3239  // The definition of this variable could be constexpr. We can't
3240  // access it right now, but may be able to in future.
3241  } else if (Info.getLangOpts().CPlusPlus11) {
3242  Info.FFDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD;
3243  Info.Note(VD->getLocation(), diag::note_declared_at);
3244  } else {
3245  Info.FFDiag(E);
3246  }
3247  return CompleteObject();
3248  }
3249  }
3250 
3251  if (!evaluateVarDeclInit(Info, E, VD, Frame, BaseVal, &LVal))
3252  return CompleteObject();
3253  } else {
3254  const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
3255 
3256  if (!Frame) {
3257  if (const MaterializeTemporaryExpr *MTE =
3258  dyn_cast<MaterializeTemporaryExpr>(Base)) {
3259  assert(MTE->getStorageDuration() == SD_Static &&
3260  "should have a frame for a non-global materialized temporary");
3261 
3262  // Per C++1y [expr.const]p2:
3263  // an lvalue-to-rvalue conversion [is not allowed unless it applies to]
3264  // - a [...] glvalue of integral or enumeration type that refers to
3265  // a non-volatile const object [...]
3266  // [...]
3267  // - a [...] glvalue of literal type that refers to a non-volatile
3268  // object whose lifetime began within the evaluation of e.
3269  //
3270  // C++11 misses the 'began within the evaluation of e' check and
3271  // instead allows all temporaries, including things like:
3272  // int &&r = 1;
3273  // int x = ++r;
3274  // constexpr int k = r;
3275  // Therefore we use the C++14 rules in C++11 too.
3276  const ValueDecl *VD = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>();
3277  const ValueDecl *ED = MTE->getExtendingDecl();
3278  if (!(BaseType.isConstQualified() &&
3279  BaseType->isIntegralOrEnumerationType()) &&
3280  !(VD && VD->getCanonicalDecl() == ED->getCanonicalDecl())) {
3281  Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
3282  Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
3283  return CompleteObject();
3284  }
3285 
3286  BaseVal = Info.Ctx.getMaterializedTemporaryValue(MTE, false);
3287  assert(BaseVal && "got reference to unevaluated temporary");
3288  LifetimeStartedInEvaluation = true;
3289  } else {
3290  Info.FFDiag(E);
3291  return CompleteObject();
3292  }
3293  } else {
3294  BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
3295  assert(BaseVal && "missing value for temporary");
3296  }
3297 
3298  // Volatile temporary objects cannot be accessed in constant expressions.
3299  if (BaseType.isVolatileQualified()) {
3300  if (Info.getLangOpts().CPlusPlus) {
3301  Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
3302  << AK << 0;
3303  Info.Note(Base->getExprLoc(), diag::note_constexpr_temporary_here);
3304  } else {
3305  Info.FFDiag(E);
3306  }
3307  return CompleteObject();
3308  }
3309  }
3310 
3311  // During the construction of an object, it is not yet 'const'.
3312  // FIXME: This doesn't do quite the right thing for const subobjects of the
3313  // object under construction.
3314  if (Info.isEvaluatingConstructor(LVal.getLValueBase(),
3315  LVal.getLValueCallIndex(),
3316  LVal.getLValueVersion())) {
3317  BaseType = Info.Ctx.getCanonicalType(BaseType);
3318  BaseType.removeLocalConst();
3319  LifetimeStartedInEvaluation = true;
3320  }
3321 
3322  // In C++14, we can't safely access any mutable state when we might be
3323  // evaluating after an unmodeled side effect.
3324  //
3325  // FIXME: Not all local state is mutable. Allow local constant subobjects
3326  // to be read here (but take care with 'mutable' fields).
3327  if ((Frame && Info.getLangOpts().CPlusPlus14 &&
3328  Info.EvalStatus.HasSideEffects) ||
3329  (AK != AK_Read && Info.IsSpeculativelyEvaluating))
3330  return CompleteObject();
3331 
3332  return CompleteObject(BaseVal, BaseType, LifetimeStartedInEvaluation);
3333 }
3334 
3335 /// Perform an lvalue-to-rvalue conversion on the given glvalue. This
3336 /// can also be used for 'lvalue-to-lvalue' conversions for looking up the
3337 /// glvalue referred to by an entity of reference type.
3338 ///
3339 /// \param Info - Information about the ongoing evaluation.
3340 /// \param Conv - The expression for which we are performing the conversion.
3341 /// Used for diagnostics.
3342 /// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
3343 /// case of a non-class type).
3344 /// \param LVal - The glvalue on which we are attempting to perform this action.
3345 /// \param RVal - The produced value will be placed here.
3346 static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv,
3347  QualType Type,
3348  const LValue &LVal, APValue &RVal) {
3349  if (LVal.Designator.Invalid)
3350  return false;
3351 
3352  // Check for special cases where there is no existing APValue to look at.
3353  const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
3354  if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
3355  if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
3356  // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
3357  // initializer until now for such expressions. Such an expression can't be
3358  // an ICE in C, so this only matters for fold.
3359  if (Type.isVolatileQualified()) {
3360  Info.FFDiag(Conv);
3361  return false;
3362  }
3363  APValue Lit;
3364  if (!Evaluate(Lit, Info, CLE->getInitializer()))
3365  return false;
3366  CompleteObject LitObj(&Lit, Base->getType(), false);
3367  return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal);
3368  } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
3369  // We represent a string literal array as an lvalue pointing at the
3370  // corresponding expression, rather than building an array of chars.
3371  // FIXME: Support ObjCEncodeExpr, MakeStringConstant
3372  APValue Str(Base, CharUnits::Zero(), APValue::NoLValuePath(), 0);
3373  CompleteObject StrObj(&Str, Base->getType(), false);
3374  return extractSubobject(Info, Conv, StrObj, LVal.Designator, RVal);
3375  }
3376  }
3377 
3378  CompleteObject Obj = findCompleteObject(Info, Conv, AK_Read, LVal, Type);
3379  return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal);
3380 }
3381 
3382 /// Perform an assignment of Val to LVal. Takes ownership of Val.
3383 static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
3384  QualType LValType, APValue &Val) {
3385  if (LVal.Designator.Invalid)
3386  return false;
3387 
3388  if (!Info.getLangOpts().CPlusPlus14) {
3389  Info.FFDiag(E);
3390  return false;
3391  }
3392 
3393  CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
3394  return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
3395 }
3396 
3397 namespace {
3398 struct CompoundAssignSubobjectHandler {
3399  EvalInfo &Info;
3400  const Expr *E;
3401  QualType PromotedLHSType;
3402  BinaryOperatorKind Opcode;
3403  const APValue &RHS;
3404 
3405  static const AccessKinds AccessKind = AK_Assign;
3406 
3407  typedef bool result_type;
3408 
3409  bool checkConst(QualType QT) {
3410  // Assigning to a const object has undefined behavior.
3411  if (QT.isConstQualified()) {
3412  Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3413  return false;
3414  }
3415  return true;
3416  }
3417 
3418  bool failed() { return false; }
3419  bool found(APValue &Subobj, QualType SubobjType) {
3420  switch (Subobj.getKind()) {
3421  case APValue::Int:
3422  return found(Subobj.getInt(), SubobjType);
3423  case APValue::Float:
3424  return found(Subobj.getFloat(), SubobjType);
3425  case APValue::ComplexInt:
3426  case APValue::ComplexFloat:
3427  // FIXME: Implement complex compound assignment.
3428  Info.FFDiag(E);
3429  return false;
3430  case APValue::LValue:
3431  return foundPointer(Subobj, SubobjType);
3432  default:
3433  // FIXME: can this happen?
3434  Info.FFDiag(E);
3435  return false;
3436  }
3437  }
3438  bool found(APSInt &Value, QualType SubobjType) {
3439  if (!checkConst(SubobjType))
3440  return false;
3441 
3442  if (!SubobjType->isIntegerType()) {
3443  // We don't support compound assignment on integer-cast-to-pointer
3444  // values.
3445  Info.FFDiag(E);
3446  return false;
3447  }
3448 
3449  if (RHS.isInt()) {
3450  APSInt LHS =
3451  HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
3452  if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
3453  return false;
3454  Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
3455  return true;
3456  } else if (RHS.isFloat()) {
3457  APFloat FValue(0.0);
3458  return HandleIntToFloatCast(Info, E, SubobjType, Value, PromotedLHSType,
3459  FValue) &&
3460  handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
3461  HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
3462  Value);
3463  }
3464 
3465  Info.FFDiag(E);
3466  return false;
3467  }
3468  bool found(APFloat &Value, QualType SubobjType) {
3469  return checkConst(SubobjType) &&
3470  HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
3471  Value) &&
3472  handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
3473  HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
3474  }
3475  bool foundPointer(APValue &Subobj, QualType SubobjType) {
3476  if (!checkConst(SubobjType))
3477  return false;
3478 
3479  QualType PointeeType;
3480  if (const PointerType *PT = SubobjType->getAs<PointerType>())
3481  PointeeType = PT->getPointeeType();
3482 
3483  if (PointeeType.isNull() || !RHS.isInt() ||
3484  (Opcode != BO_Add && Opcode != BO_Sub)) {
3485  Info.FFDiag(E);
3486  return false;
3487  }
3488 
3489  APSInt Offset = RHS.getInt();
3490  if (Opcode == BO_Sub)
3491  negateAsSigned(Offset);
3492 
3493  LValue LVal;
3494  LVal.setFrom(Info.Ctx, Subobj);
3495  if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
3496  return false;
3497  LVal.moveInto(Subobj);
3498  return true;
3499  }
3500  bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
3501  llvm_unreachable("shouldn't encounter string elements here");
3502  }
3503 };
3504 } // end anonymous namespace
3505 
3507 
3508 /// Perform a compound assignment of LVal <op>= RVal.
3510  EvalInfo &Info, const Expr *E,
3511  const LValue &LVal, QualType LValType, QualType PromotedLValType,
3512  BinaryOperatorKind Opcode, const APValue &RVal) {
3513  if (LVal.Designator.Invalid)
3514  return false;
3515 
3516  if (!Info.getLangOpts().CPlusPlus14) {
3517  Info.FFDiag(E);
3518  return false;
3519  }
3520 
3521  CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
3522  CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
3523  RVal };
3524  return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
3525 }
3526 
3527 namespace {
3528 struct IncDecSubobjectHandler {
3529  EvalInfo &Info;
3530  const UnaryOperator *E;
3532  APValue *Old;
3533 
3534  typedef bool result_type;
3535 
3536  bool checkConst(QualType QT) {
3537  // Assigning to a const object has undefined behavior.
3538  if (QT.isConstQualified()) {
3539  Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
3540  return false;
3541  }
3542  return true;
3543  }
3544 
3545  bool failed() { return false; }
3546  bool found(APValue &Subobj, QualType SubobjType) {
3547  // Stash the old value. Also clear Old, so we don't clobber it later
3548  // if we're post-incrementing a complex.
3549  if (Old) {
3550  *Old = Subobj;
3551  Old = nullptr;
3552  }
3553 
3554  switch (Subobj.getKind()) {
3555  case APValue::Int:
3556  return found(Subobj.getInt(), SubobjType);
3557  case APValue::Float:
3558  return found(Subobj.getFloat(), SubobjType);
3559  case APValue::ComplexInt:
3560  return found(Subobj.getComplexIntReal(),
3561  SubobjType->castAs<ComplexType>()->getElementType()
3562  .withCVRQualifiers(SubobjType.getCVRQualifiers()));
3563  case APValue::ComplexFloat:
3564  return found(Subobj.getComplexFloatReal(),
3565  SubobjType->castAs<ComplexType>()->getElementType()
3566  .withCVRQualifiers(SubobjType.getCVRQualifiers()));
3567  case APValue::LValue:
3568  return foundPointer(Subobj, SubobjType);
3569  default:
3570  // FIXME: can this happen?
3571  Info.FFDiag(E);
3572  return false;
3573  }
3574  }
3575  bool found(APSInt &Value, QualType SubobjType) {
3576  if (!checkConst(SubobjType))
3577  return false;
3578 
3579  if (!SubobjType->isIntegerType()) {
3580  // We don't support increment / decrement on integer-cast-to-pointer
3581  // values.
3582  Info.FFDiag(E);
3583  return false;
3584  }
3585 
3586  if (Old) *Old = APValue(Value);
3587 
3588  // bool arithmetic promotes to int, and the conversion back to bool
3589  // doesn't reduce mod 2^n, so special-case it.
3590  if (SubobjType->isBooleanType()) {
3591  if (AccessKind == AK_Increment)
3592  Value = 1;
3593  else
3594  Value = !Value;
3595  return true;
3596  }
3597 
3598  bool WasNegative = Value.isNegative();
3599  if (AccessKind == AK_Increment) {
3600  ++Value;
3601 
3602  if (!WasNegative && Value.isNegative() && E->canOverflow()) {
3603  APSInt ActualValue(Value, /*IsUnsigned*/true);
3604  return HandleOverflow(Info, E, ActualValue, SubobjType);
3605  }
3606  } else {
3607  --Value;
3608 
3609  if (WasNegative && !Value.isNegative() && E->canOverflow()) {
3610  unsigned BitWidth = Value.getBitWidth();
3611  APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
3612  ActualValue.setBit(BitWidth);
3613  return HandleOverflow(Info, E, ActualValue, SubobjType);
3614  }
3615  }
3616  return true;
3617  }
3618  bool found(APFloat &Value, QualType SubobjType) {
3619  if (!checkConst(SubobjType))
3620  return false;
3621 
3622  if (Old) *Old = APValue(Value);
3623 
3624  APFloat One(Value.getSemantics(), 1);
3625  if (AccessKind == AK_Increment)
3626  Value.add(One, APFloat::rmNearestTiesToEven);
3627  else
3628  Value.subtract(One, APFloat::rmNearestTiesToEven);
3629  return true;
3630  }
3631  bool foundPointer(APValue &Subobj, QualType SubobjType) {
3632  if (!checkConst(SubobjType))
3633  return false;
3634 
3635  QualType PointeeType;
3636  if (const PointerType *PT = SubobjType->getAs<PointerType>())
3637  PointeeType = PT->getPointeeType();
3638  else {
3639  Info.FFDiag(E);
3640  return false;
3641  }
3642 
3643  LValue LVal;
3644  LVal.setFrom(Info.Ctx, Subobj);
3645  if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
3646  AccessKind == AK_Increment ? 1 : -1))
3647  return false;
3648  LVal.moveInto(Subobj);
3649  return true;
3650  }
3651  bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
3652  llvm_unreachable("shouldn't encounter string elements here");
3653  }
3654 };
3655 } // end anonymous namespace
3656 
3657 /// Perform an increment or decrement on LVal.
3658 static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
3659  QualType LValType, bool IsIncrement, APValue *Old) {
3660  if (LVal.Designator.Invalid)
3661  return false;
3662 
3663  if (!Info.getLangOpts().CPlusPlus14) {
3664  Info.FFDiag(E);
3665  return false;
3666  }
3667 
3668  AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
3669  CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
3670  IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old};
3671  return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
3672 }
3673 
3674 /// Build an lvalue for the object argument of a member function call.
3675 static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
3676  LValue &This) {
3677  if (Object->getType()->isPointerType())
3678  return EvaluatePointer(Object, This, Info);
3679 
3680  if (Object->isGLValue())
3681  return EvaluateLValue(Object, This, Info);
3682 
3683  if (Object->getType()->isLiteralType(Info.Ctx))
3684  return EvaluateTemporary(Object, This, Info);
3685 
3686  Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
3687  return false;
3688 }
3689 
3690 /// HandleMemberPointerAccess - Evaluate a member access operation and build an
3691 /// lvalue referring to the result.
3692 ///
3693 /// \param Info - Information about the ongoing evaluation.
3694 /// \param LV - An lvalue referring to the base of the member pointer.
3695 /// \param RHS - The member pointer expression.
3696 /// \param IncludeMember - Specifies whether the member itself is included in
3697 /// the resulting LValue subobject designator. This is not possible when
3698 /// creating a bound member function.
3699 /// \return The field or method declaration to which the member pointer refers,
3700 /// or 0 if evaluation fails.
3701 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
3702  QualType LVType,
3703  LValue &LV,
3704  const Expr *RHS,
3705  bool IncludeMember = true) {
3706  MemberPtr MemPtr;
3707  if (!EvaluateMemberPointer(RHS, MemPtr, Info))
3708  return nullptr;
3709 
3710  // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
3711  // member value, the behavior is undefined.
3712  if (!MemPtr.getDecl()) {
3713  // FIXME: Specific diagnostic.
3714  Info.FFDiag(RHS);
3715  return nullptr;
3716  }
3717 
3718  if (MemPtr.isDerivedMember()) {
3719  // This is a member of some derived class. Truncate LV appropriately.
3720  // The end of the derived-to-base path for the base object must match the
3721  // derived-to-base path for the member pointer.
3722  if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
3723  LV.Designator.Entries.size()) {
3724  Info.FFDiag(RHS);
3725  return nullptr;
3726  }
3727  unsigned PathLengthToMember =
3728  LV.Designator.Entries.size() - MemPtr.Path.size();
3729  for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
3730  const CXXRecordDecl *LVDecl = getAsBaseClass(
3731  LV.Designator.Entries[PathLengthToMember + I]);
3732  const CXXRecordDecl *MPDecl = MemPtr.Path[I];
3733  if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
3734  Info.FFDiag(RHS);
3735  return nullptr;
3736  }
3737  }
3738 
3739  // Truncate the lvalue to the appropriate derived class.
3740  if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
3741  PathLengthToMember))
3742  return nullptr;
3743  } else if (!MemPtr.Path.empty()) {
3744  // Extend the LValue path with the member pointer's path.
3745  LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
3746  MemPtr.Path.size() + IncludeMember);
3747 
3748  // Walk down to the appropriate base class.
3749  if (const PointerType *PT = LVType->getAs<PointerType>())
3750  LVType = PT->getPointeeType();
3751  const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
3752  assert(RD && "member pointer access on non-class-type expression");
3753  // The first class in the path is that of the lvalue.
3754  for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
3755  const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
3756  if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
3757  return nullptr;
3758  RD = Base;
3759  }
3760  // Finally cast to the class containing the member.
3761  if (!HandleLValueDirectBase(Info, RHS, LV, RD,
3762  MemPtr.getContainingRecord()))
3763  return nullptr;
3764  }
3765 
3766  // Add the member. Note that we cannot build bound member functions here.
3767  if (IncludeMember) {
3768  if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
3769  if (!HandleLValueMember(Info, RHS, LV, FD))
3770  return nullptr;
3771  } else if (const IndirectFieldDecl *IFD =
3772  dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
3773  if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
3774  return nullptr;
3775  } else {
3776  llvm_unreachable("can't construct reference to bound member function");
3777  }
3778  }
3779 
3780  return MemPtr.getDecl();
3781 }
3782 
3783 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
3784  const BinaryOperator *BO,
3785  LValue &LV,
3786  bool IncludeMember = true) {
3787  assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI);
3788 
3789  if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
3790  if (Info.noteFailure()) {
3791  MemberPtr MemPtr;
3792  EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
3793  }
3794  return nullptr;
3795  }
3796 
3797  return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
3798  BO->getRHS(), IncludeMember);
3799 }
3800 
3801 /// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
3802 /// the provided lvalue, which currently refers to the base object.
3803 static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
3804  LValue &Result) {
3805  SubobjectDesignator &D = Result.Designator;
3806  if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
3807  return false;
3808 
3809  QualType TargetQT = E->getType();
3810  if (const PointerType *PT = TargetQT->getAs<PointerType>())
3811  TargetQT = PT->getPointeeType();
3812 
3813  // Check this cast lands within the final derived-to-base subobject path.
3814  if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
3815  Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
3816  << D.MostDerivedType << TargetQT;
3817  return false;
3818  }
3819 
3820  // Check the type of the final cast. We don't need to check the path,
3821  // since a cast can only be formed if the path is unique.
3822  unsigned NewEntriesSize = D.Entries.size() - E->path_size();
3823  const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
3824  const CXXRecordDecl *FinalType;
3825  if (NewEntriesSize == D.MostDerivedPathLength)
3826  FinalType = D.MostDerivedType->getAsCXXRecordDecl();
3827  else
3828  FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
3829  if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
3830  Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
3831  << D.MostDerivedType << TargetQT;
3832  return false;
3833  }
3834 
3835  // Truncate the lvalue to the appropriate derived class.
3836  return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
3837 }
3838 
3839 namespace {
3841  /// Evaluation failed.
3842  ESR_Failed,
3843  /// Hit a 'return' statement.
3844  ESR_Returned,
3845  /// Evaluation succeeded.
3846  ESR_Succeeded,
3847  /// Hit a 'continue' statement.
3848  ESR_Continue,
3849  /// Hit a 'break' statement.
3850  ESR_Break,
3851  /// Still scanning for 'case' or 'default' statement.
3852  ESR_CaseNotFound
3853 };
3854 }
3855 
3856 static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
3857  // We don't need to evaluate the initializer for a static local.
3858  if (!VD->hasLocalStorage())
3859  return true;
3860 
3861  LValue Result;
3862  APValue &Val = createTemporary(VD, true, Result, *Info.CurrentCall);
3863 
3864  const Expr *InitE = VD->getInit();
3865  if (!InitE) {
3866  Info.FFDiag(VD->getBeginLoc(), diag::note_constexpr_uninitialized)
3867  << false << VD->getType();
3868  Val = APValue();
3869  return false;
3870  }
3871 
3872  if (InitE->isValueDependent())
3873  return false;
3874 
3875  if (!EvaluateInPlace(Val, Info, Result, InitE)) {
3876  // Wipe out any partially-computed value, to allow tracking that this
3877  // evaluation failed.
3878  Val = APValue();
3879  return false;
3880  }
3881 
3882  return true;
3883 }
3884 
3885 static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
3886  bool OK = true;
3887 
3888  if (const VarDecl *VD = dyn_cast<VarDecl>(D))
3889  OK &= EvaluateVarDecl(Info, VD);
3890 
3891  if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
3892  for (auto *BD : DD->bindings())
3893  if (auto *VD = BD->getHoldingVar())
3894  OK &= EvaluateDecl(Info, VD);
3895 
3896  return OK;
3897 }
3898 
3899 
3900 /// Evaluate a condition (either a variable declaration or an expression).
3901 static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
3902  const Expr *Cond, bool &Result) {
3903  FullExpressionRAII Scope(Info);
3904  if (CondDecl && !EvaluateDecl(Info, CondDecl))
3905  return false;
3906  return EvaluateAsBooleanCondition(Cond, Result, Info);
3907 }
3908 
3909 namespace {
3910 /// A location where the result (returned value) of evaluating a
3911 /// statement should be stored.
3912 struct StmtResult {
3913  /// The APValue that should be filled in with the returned value.
3914  APValue &Value;
3915  /// The location containing the result, if any (used to support RVO).
3916  const LValue *Slot;
3917 };
3918 
3919 struct TempVersionRAII {
3920  CallStackFrame &Frame;
3921 
3922  TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
3923  Frame.pushTempVersion();
3924  }
3925 
3926  ~TempVersionRAII() {
3927  Frame.popTempVersion();
3928  }
3929 };
3930 
3931 }
3932 
3933 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
3934  const Stmt *S,
3935  const SwitchCase *SC = nullptr);
3936 
3937 /// Evaluate the body of a loop, and translate the result as appropriate.
3938 static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
3939  const Stmt *Body,
3940  const SwitchCase *Case = nullptr) {
3941  BlockScopeRAII Scope(Info);
3942  switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case)) {
3943  case ESR_Break:
3944  return ESR_Succeeded;
3945  case ESR_Succeeded:
3946  case ESR_Continue:
3947  return ESR_Continue;
3948  case ESR_Failed:
3949  case ESR_Returned:
3950  case ESR_CaseNotFound:
3951  return ESR;
3952  }
3953  llvm_unreachable("Invalid EvalStmtResult!");
3954 }
3955 
3956 /// Evaluate a switch statement.
3957 static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
3958  const SwitchStmt *SS) {
3959  BlockScopeRAII Scope(Info);
3960 
3961  // Evaluate the switch condition.
3962  APSInt Value;
3963  {
3964  FullExpressionRAII Scope(Info);
3965  if (const Stmt *Init = SS->getInit()) {
3966  EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
3967  if (ESR != ESR_Succeeded)
3968  return ESR;
3969  }
3970  if (SS->getConditionVariable() &&
3971  !EvaluateDecl(Info, SS->getConditionVariable()))
3972  return ESR_Failed;
3973  if (!EvaluateInteger(SS->getCond(), Value, Info))
3974  return ESR_Failed;
3975  }
3976 
3977  // Find the switch case corresponding to the value of the condition.
3978  // FIXME: Cache this lookup.
3979  const SwitchCase *Found = nullptr;
3980  for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
3981  SC = SC->getNextSwitchCase()) {
3982  if (isa<DefaultStmt>(SC)) {
3983  Found = SC;
3984  continue;
3985  }
3986 
3987  const CaseStmt *CS = cast<CaseStmt>(SC);
3988  APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
3989  APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
3990  : LHS;
3991  if (LHS <= Value && Value <= RHS) {
3992  Found = SC;
3993  break;
3994  }
3995  }
3996 
3997  if (!Found)
3998  return ESR_Succeeded;
3999 
4000  // Search the switch body for the switch case and evaluate it from there.
4001  switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found)) {
4002  case ESR_Break:
4003  return ESR_Succeeded;
4004  case ESR_Succeeded:
4005  case ESR_Continue:
4006  case ESR_Failed:
4007  case ESR_Returned:
4008  return ESR;
4009  case ESR_CaseNotFound:
4010  // This can only happen if the switch case is nested within a statement
4011  // expression. We have no intention of supporting that.
4012  Info.FFDiag(Found->getBeginLoc(),
4013  diag::note_constexpr_stmt_expr_unsupported);
4014  return ESR_Failed;
4015  }
4016  llvm_unreachable("Invalid EvalStmtResult!");
4017 }
4018 
4019 // Evaluate a statement.
4020 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
4021  const Stmt *S, const SwitchCase *Case) {
4022  if (!Info.nextStep(S))
4023  return ESR_Failed;
4024 
4025  // If we're hunting down a 'case' or 'default' label, recurse through
4026  // substatements until we hit the label.
4027  if (Case) {
4028  // FIXME: We don't start the lifetime of objects whose initialization we
4029  // jump over. However, such objects must be of class type with a trivial
4030  // default constructor that initialize all subobjects, so must be empty,
4031  // so this almost never matters.
4032  switch (S->getStmtClass()) {
4033  case Stmt::CompoundStmtClass:
4034  // FIXME: Precompute which substatement of a compound statement we
4035  // would jump to, and go straight there rather than performing a
4036  // linear scan each time.
4037  case Stmt::LabelStmtClass:
4038  case Stmt::AttributedStmtClass:
4039  case Stmt::DoStmtClass:
4040  break;
4041 
4042  case Stmt::CaseStmtClass:
4043  case Stmt::DefaultStmtClass:
4044  if (Case == S)
4045  Case = nullptr;
4046  break;
4047 
4048  case Stmt::IfStmtClass: {
4049  // FIXME: Precompute which side of an 'if' we would jump to, and go
4050  // straight there rather than scanning both sides.
4051  const IfStmt *IS = cast<IfStmt>(S);
4052 
4053  // Wrap the evaluation in a block scope, in case it's a DeclStmt
4054  // preceded by our switch label.
4055  BlockScopeRAII Scope(Info);
4056 
4057  EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
4058  if (ESR != ESR_CaseNotFound || !IS->getElse())
4059  return ESR;
4060  return EvaluateStmt(Result, Info, IS->getElse(), Case);
4061  }
4062 
4063  case Stmt::WhileStmtClass: {
4064  EvalStmtResult ESR =
4065  EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
4066  if (ESR != ESR_Continue)
4067  return ESR;
4068  break;
4069  }
4070 
4071  case Stmt::ForStmtClass: {
4072  const ForStmt *FS = cast<ForStmt>(S);
4073  EvalStmtResult ESR =
4074  EvaluateLoopBody(Result, Info, FS->getBody(), Case);
4075  if (ESR != ESR_Continue)
4076  return ESR;
4077  if (FS->getInc()) {
4078  FullExpressionRAII IncScope(Info);
4079  if (!EvaluateIgnoredValue(Info, FS->getInc()))
4080  return ESR_Failed;
4081  }
4082  break;
4083  }
4084 
4085  case Stmt::DeclStmtClass:
4086  // FIXME: If the variable has initialization that can't be jumped over,
4087  // bail out of any immediately-surrounding compound-statement too.
4088  default:
4089  return ESR_CaseNotFound;
4090  }
4091  }
4092 
4093  switch (S->getStmtClass()) {
4094  default:
4095  if (const Expr *E = dyn_cast<Expr>(S)) {
4096  // Don't bother evaluating beyond an expression-statement which couldn't
4097  // be evaluated.
4098  FullExpressionRAII Scope(Info);
4099  if (!EvaluateIgnoredValue(Info, E))
4100  return ESR_Failed;
4101  return ESR_Succeeded;
4102  }
4103 
4104  Info.FFDiag(S->getBeginLoc());
4105  return ESR_Failed;
4106 
4107  case Stmt::NullStmtClass:
4108  return ESR_Succeeded;
4109 
4110  case Stmt::DeclStmtClass: {
4111  const DeclStmt *DS = cast<DeclStmt>(S);
4112  for (const auto *DclIt : DS->decls()) {
4113  // Each declaration initialization is its own full-expression.
4114  // FIXME: This isn't quite right; if we're performing aggregate
4115  // initialization, each braced subexpression is its own full-expression.
4116  FullExpressionRAII Scope(Info);
4117  if (!EvaluateDecl(Info, DclIt) && !Info.noteFailure())
4118  return ESR_Failed;
4119  }
4120  return ESR_Succeeded;
4121  }
4122 
4123  case Stmt::ReturnStmtClass: {
4124  const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
4125  FullExpressionRAII Scope(Info);
4126  if (RetExpr &&
4127  !(Result.Slot
4128  ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
4129  : Evaluate(Result.Value, Info, RetExpr)))
4130  return ESR_Failed;
4131  return ESR_Returned;
4132  }
4133 
4134  case Stmt::CompoundStmtClass: {
4135  BlockScopeRAII Scope(Info);
4136 
4137  const CompoundStmt *CS = cast<CompoundStmt>(S);
4138  for (const auto *BI : CS->body()) {
4139  EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
4140  if (ESR == ESR_Succeeded)
4141  Case = nullptr;
4142  else if (ESR != ESR_CaseNotFound)
4143  return ESR;
4144  }
4145  return Case ? ESR_CaseNotFound : ESR_Succeeded;
4146  }
4147 
4148  case Stmt::IfStmtClass: {
4149  const IfStmt *IS = cast<IfStmt>(S);
4150 
4151  // Evaluate the condition, as either a var decl or as an expression.
4152  BlockScopeRAII Scope(Info);
4153  if (const Stmt *Init = IS->getInit()) {
4154  EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
4155  if (ESR != ESR_Succeeded)
4156  return ESR;
4157  }
4158  bool Cond;
4159  if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond))
4160  return ESR_Failed;
4161 
4162  if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
4163  EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
4164  if (ESR != ESR_Succeeded)
4165  return ESR;
4166  }
4167  return ESR_Succeeded;
4168  }
4169 
4170  case Stmt::WhileStmtClass: {
4171  const WhileStmt *WS = cast<WhileStmt>(S);
4172  while (true) {
4173  BlockScopeRAII Scope(Info);
4174  bool Continue;
4175  if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
4176  Continue))
4177  return ESR_Failed;
4178  if (!Continue)
4179  break;
4180 
4181  EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
4182  if (ESR != ESR_Continue)
4183  return ESR;
4184  }
4185  return ESR_Succeeded;
4186  }
4187 
4188  case Stmt::DoStmtClass: {
4189  const DoStmt *DS = cast<DoStmt>(S);
4190  bool Continue;
4191  do {
4192  EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
4193  if (ESR != ESR_Continue)
4194  return ESR;
4195  Case = nullptr;
4196 
4197  FullExpressionRAII CondScope(Info);
4198  if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info))
4199  return ESR_Failed;
4200  } while (Continue);
4201  return ESR_Succeeded;
4202  }
4203 
4204  case Stmt::ForStmtClass: {
4205  const ForStmt *FS = cast<ForStmt>(S);
4206  BlockScopeRAII Scope(Info);
4207  if (FS->getInit()) {
4208  EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
4209  if (ESR != ESR_Succeeded)
4210  return ESR;
4211  }
4212  while (true) {
4213  BlockScopeRAII Scope(Info);
4214  bool Continue = true;
4215  if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
4216  FS->getCond(), Continue))
4217  return ESR_Failed;
4218  if (!Continue)
4219  break;
4220 
4221  EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
4222  if (ESR != ESR_Continue)
4223  return ESR;
4224 
4225  if (FS->getInc()) {
4226  FullExpressionRAII IncScope(Info);
4227  if (!EvaluateIgnoredValue(Info, FS->getInc()))
4228  return ESR_Failed;
4229  }
4230  }
4231  return ESR_Succeeded;
4232  }
4233 
4234  case Stmt::CXXForRangeStmtClass: {
4235  const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
4236  BlockScopeRAII Scope(Info);
4237 
4238  // Evaluate the init-statement if present.
4239  if (FS->getInit()) {
4240  EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
4241  if (ESR != ESR_Succeeded)
4242  return ESR;
4243  }
4244 
4245  // Initialize the __range variable.
4246  EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
4247  if (ESR != ESR_Succeeded)
4248  return ESR;
4249 
4250  // Create the __begin and __end iterators.
4251  ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
4252  if (ESR != ESR_Succeeded)
4253  return ESR;
4254  ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
4255  if (ESR != ESR_Succeeded)
4256  return ESR;
4257 
4258  while (true) {
4259  // Condition: __begin != __end.
4260  {
4261  bool Continue = true;
4262  FullExpressionRAII CondExpr(Info);
4263  if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
4264  return ESR_Failed;
4265  if (!Continue)
4266  break;
4267  }
4268 
4269  // User's variable declaration, initialized by *__begin.
4270  BlockScopeRAII InnerScope(Info);
4271  ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
4272  if (ESR != ESR_Succeeded)
4273  return ESR;
4274 
4275  // Loop body.
4276  ESR = EvaluateLoopBody(Result, Info, FS->getBody());
4277  if (ESR != ESR_Continue)
4278  return ESR;
4279 
4280  // Increment: ++__begin
4281  if (!EvaluateIgnoredValue(Info, FS->getInc()))
4282  return ESR_Failed;
4283  }
4284 
4285  return ESR_Succeeded;
4286  }
4287 
4288  case Stmt::SwitchStmtClass:
4289  return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
4290 
4291  case Stmt::ContinueStmtClass:
4292  return ESR_Continue;
4293 
4294  case Stmt::BreakStmtClass:
4295  return ESR_Break;
4296 
4297  case Stmt::LabelStmtClass:
4298  return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
4299 
4300  case Stmt::AttributedStmtClass:
4301  // As a general principle, C++11 attributes can be ignored without
4302  // any semantic impact.
4303  return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(),
4304  Case);
4305 
4306  case Stmt::CaseStmtClass:
4307  case Stmt::DefaultStmtClass:
4308  return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
4309  case Stmt::CXXTryStmtClass:
4310  // Evaluate try blocks by evaluating all sub statements.
4311  return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case);
4312  }
4313 }
4314 
4315 /// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
4316 /// default constructor. If so, we'll fold it whether or not it's marked as
4317 /// constexpr. If it is marked as constexpr, we will never implicitly define it,
4318 /// so we need special handling.
4319 static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
4320  const CXXConstructorDecl *CD,
4321  bool IsValueInitialization) {
4322  if (!CD->isTrivial() || !CD->isDefaultConstructor())
4323  return false;
4324 
4325  // Value-initialization does not call a trivial default constructor, so such a
4326  // call is a core constant expression whether or not the constructor is
4327  // constexpr.
4328  if (!CD->isConstexpr() && !IsValueInitialization) {
4329  if (Info.getLangOpts().CPlusPlus11) {
4330  // FIXME: If DiagDecl is an implicitly-declared special member function,
4331  // we should be much more explicit about why it's not constexpr.
4332  Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
4333  << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
4334  Info.Note(CD->getLocation(), diag::note_declared_at);
4335  } else {
4336  Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
4337  }
4338  }
4339  return true;
4340 }
4341 
4342 /// CheckConstexprFunction - Check that a function can be called in a constant
4343 /// expression.
4344 static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
4345  const FunctionDecl *Declaration,
4346  const FunctionDecl *Definition,
4347  const Stmt *Body) {
4348  // Potential constant expressions can contain calls to declared, but not yet
4349  // defined, constexpr functions.
4350  if (Info.checkingPotentialConstantExpression() && !Definition &&
4351  Declaration->isConstexpr())
4352  return false;
4353 
4354  // Bail out if the function declaration itself is invalid. We will
4355  // have produced a relevant diagnostic while parsing it, so just
4356  // note the problematic sub-expression.
4357  if (Declaration->isInvalidDecl()) {
4358  Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
4359  return false;
4360  }
4361 
4362  // Can we evaluate this function call?
4363  if (Definition && Definition->isConstexpr() &&
4364  !Definition->isInvalidDecl() && Body)
4365  return true;
4366 
4367  if (Info.getLangOpts().CPlusPlus11) {
4368  const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
4369 
4370  // If this function is not constexpr because it is an inherited
4371  // non-constexpr constructor, diagnose that directly.
4372  auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
4373  if (CD && CD->isInheritingConstructor()) {
4374  auto *Inherited = CD->getInheritedConstructor().getConstructor();
4375  if (!Inherited->isConstexpr())
4376  DiagDecl = CD = Inherited;
4377  }
4378 
4379  // FIXME: If DiagDecl is an implicitly-declared special member function
4380  // or an inheriting constructor, we should be much more explicit about why
4381  // it's not constexpr.
4382  if (CD && CD->isInheritingConstructor())
4383  Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
4384  << CD->getInheritedConstructor().getConstructor()->getParent();
4385  else
4386  Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
4387  << DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
4388  Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
4389  } else {
4390  Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
4391  }
4392  return false;
4393 }
4394 
4395 /// Determine if a class has any fields that might need to be copied by a
4396 /// trivial copy or move operation.
4397 static bool hasFields(const CXXRecordDecl *RD) {
4398  if (!RD || RD->isEmpty())
4399  return false;
4400  for (auto *FD : RD->fields()) {
4401  if (FD->isUnnamedBitfield())
4402  continue;
4403  return true;
4404  }
4405  for (auto &Base : RD->bases())
4406  if (hasFields(Base.getType()->getAsCXXRecordDecl()))
4407  return true;
4408  return false;
4409 }
4410 
4411 namespace {
4412 typedef SmallVector<APValue, 8> ArgVector;
4413 }
4414 
4415 /// EvaluateArgs - Evaluate the arguments to a function call.
4416 static bool EvaluateArgs(ArrayRef<const Expr*> Args, ArgVector &ArgValues,
4417  EvalInfo &Info) {
4418  bool Success = true;
4419  for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
4420  I != E; ++I) {
4421  if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) {
4422  // If we're checking for a potential constant expression, evaluate all
4423  // initializers even if some of them fail.
4424  if (!Info.noteFailure())
4425  return false;
4426  Success = false;
4427  }
4428  }
4429  return Success;
4430 }
4431 
4432 /// Evaluate a function call.
4434  const FunctionDecl *Callee, const LValue *This,
4435  ArrayRef<const Expr*> Args, const Stmt *Body,
4436  EvalInfo &Info, APValue &Result,
4437  const LValue *ResultSlot) {
4438  ArgVector ArgValues(Args.size());
4439  if (!EvaluateArgs(Args, ArgValues, Info))
4440  return false;
4441 
4442  if (!Info.CheckCallLimit(CallLoc))
4443  return false;
4444 
4445  CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data());
4446 
4447  // For a trivial copy or move assignment, perform an APValue copy. This is
4448  // essential for unions, where the operations performed by the assignment
4449  // operator cannot be represented as statements.
4450  //
4451  // Skip this for non-union classes with no fields; in that case, the defaulted
4452  // copy/move does not actually read the object.
4453  const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee);
4454  if (MD && MD->isDefaulted() &&
4455  (MD->getParent()->isUnion() ||
4456  (MD->isTrivial() && hasFields(MD->getParent())))) {
4457  assert(This &&
4458  (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()));
4459  LValue RHS;
4460  RHS.setFrom(Info.Ctx, ArgValues[0]);
4461  APValue RHSValue;
4462  if (!handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(),
4463  RHS, RHSValue))
4464  return false;
4465  if (!handleAssignment(Info, Args[0], *This, MD->getThisType(),
4466  RHSValue))
4467  return false;
4468  This->moveInto(Result);
4469  return true;
4470  } else if (MD && isLambdaCallOperator(MD)) {
4471  // We're in a lambda; determine the lambda capture field maps unless we're
4472  // just constexpr checking a lambda's call operator. constexpr checking is
4473  // done before the captures have been added to the closure object (unless
4474  // we're inferring constexpr-ness), so we don't have access to them in this
4475  // case. But since we don't need the captures to constexpr check, we can
4476  // just ignore them.
4477  if (!Info.checkingPotentialConstantExpression())
4478  MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields,
4479  Frame.LambdaThisCaptureField);
4480  }
4481 
4482  StmtResult Ret = {Result, ResultSlot};
4483  EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body);
4484  if (ESR == ESR_Succeeded) {
4485  if (Callee->getReturnType()->isVoidType())
4486  return true;
4487  Info.FFDiag(Callee->getEndLoc(), diag::note_constexpr_no_return);
4488  }
4489  return ESR == ESR_Returned;
4490 }
4491 
4492 /// Evaluate a constructor call.
4493 static bool HandleConstructorCall(const Expr *E, const LValue &This,
4494  APValue *ArgValues,
4495  const CXXConstructorDecl *Definition,
4496  EvalInfo &Info, APValue &Result) {
4497  SourceLocation CallLoc = E->getExprLoc();
4498  if (!Info.CheckCallLimit(CallLoc))
4499  return false;
4500 
4501  const CXXRecordDecl *RD = Definition->getParent();
4502  if (RD->getNumVBases()) {
4503  Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
4504  return false;
4505  }
4506 
4507  EvalInfo::EvaluatingConstructorRAII EvalObj(
4508  Info, {This.getLValueBase(),
4509  {This.getLValueCallIndex(), This.getLValueVersion()}});
4510  CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues);
4511 
4512  // FIXME: Creating an APValue just to hold a nonexistent return value is
4513  // wasteful.
4514  APValue RetVal;
4515  StmtResult Ret = {RetVal, nullptr};
4516 
4517  // If it's a delegating constructor, delegate.
4518  if (Definition->isDelegatingConstructor()) {
4520  {
4521  FullExpressionRAII InitScope(Info);
4522  if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()))
4523  return false;
4524  }
4525  return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
4526  }
4527 
4528  // For a trivial copy or move constructor, perform an APValue copy. This is
4529  // essential for unions (or classes with anonymous union members), where the
4530  // operations performed by the constructor cannot be represented by
4531  // ctor-initializers.
4532  //
4533  // Skip this for empty non-union classes; we should not perform an
4534  // lvalue-to-rvalue conversion on them because their copy constructor does not
4535  // actually read them.
4536  if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() &&
4537  (Definition->getParent()->isUnion() ||
4538  (Definition->isTrivial() && hasFields(Definition->getParent())))) {
4539  LValue RHS;
4540  RHS.setFrom(Info.Ctx, ArgValues[0]);
4542  Info, E, Definition->getParamDecl(0)->getType().getNonReferenceType(),
4543  RHS, Result);
4544  }
4545 
4546  // Reserve space for the struct members.
4547  if (!RD->isUnion() && Result.isUninit())
4548  Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
4549  std::distance(RD->field_begin(), RD->field_end()));
4550 
4551  if (RD->isInvalidDecl()) return false;
4552  const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
4553 
4554  // A scope for temporaries lifetime-extended by reference members.
4555  BlockScopeRAII LifetimeExtendedScope(Info);
4556 
4557  bool Success = true;
4558  unsigned BasesSeen = 0;
4559 #ifndef NDEBUG
4561 #endif
4562  for (const auto *I : Definition->inits()) {
4563  LValue Subobject = This;
4564  LValue SubobjectParent = This;
4565  APValue *Value = &Result;
4566 
4567  // Determine the subobject to initialize.
4568  FieldDecl *FD = nullptr;
4569  if (I->isBaseInitializer()) {
4570  QualType BaseType(I->getBaseClass(), 0);
4571 #ifndef NDEBUG
4572  // Non-virtual base classes are initialized in the order in the class
4573  // definition. We have already checked for virtual base classes.
4574  assert(!BaseIt->isVirtual() && "virtual base for literal type");
4575  assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&
4576  "base class initializers not in expected order");
4577  ++BaseIt;
4578 #endif
4579  if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD,
4580  BaseType->getAsCXXRecordDecl(), &Layout))
4581  return false;
4582  Value = &Result.getStructBase(BasesSeen++);
4583  } else if ((FD = I->getMember())) {
4584  if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout))
4585  return false;
4586  if (RD->isUnion()) {
4587  Result = APValue(FD);
4588  Value = &Result.getUnionValue();
4589  } else {
4590  Value = &Result.getStructField(FD->getFieldIndex());
4591  }
4592  } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) {
4593  // Walk the indirect field decl's chain to find the object to initialize,
4594  // and make sure we've initialized every step along it.
4595  auto IndirectFieldChain = IFD->chain();
4596  for (auto *C : IndirectFieldChain) {
4597  FD = cast<FieldDecl>(C);
4598  CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent());
4599  // Switch the union field if it differs. This happens if we had
4600  // preceding zero-initialization, and we're now initializing a union
4601  // subobject other than the first.
4602  // FIXME: In this case, the values of the other subobjects are
4603  // specified, since zero-initialization sets all padding bits to zero.
4604  if (Value->isUninit() ||
4605  (Value->isUnion() && Value->getUnionField() != FD)) {
4606  if (CD->isUnion())
4607  *Value = APValue(FD);
4608  else
4609  *Value = APValue(APValue::UninitStruct(), CD->getNumBases(),
4610  std::distance(CD->field_begin(), CD->field_end()));
4611  }
4612  // Store Subobject as its parent before updating it for the last element
4613  // in the chain.
4614  if (C == IndirectFieldChain.back())
4615  SubobjectParent = Subobject;
4616  if (!HandleLValueMember(Info, I->getInit(), Subobject, FD))
4617  return false;
4618  if (CD->isUnion())
4619  Value = &Value->getUnionValue();
4620  else
4621  Value = &Value->getStructField(FD->getFieldIndex());
4622  }
4623  } else {
4624  llvm_unreachable("unknown base initializer kind");
4625  }
4626 
4627  // Need to override This for implicit field initializers as in this case
4628  // This refers to innermost anonymous struct/union containing initializer,
4629  // not to currently constructed class.
4630  const Expr *Init = I->getInit();
4631  ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent,
4632  isa<CXXDefaultInitExpr>(Init));
4633  FullExpressionRAII InitScope(Info);
4634  if (!EvaluateInPlace(*Value, Info, Subobject, Init) ||
4635  (FD && FD->isBitField() &&
4636  !truncateBitfieldValue(Info, Init, *Value, FD))) {
4637  // If we're checking for a potential constant expression, evaluate all
4638  // initializers even if some of them fail.
4639  if (!Info.noteFailure())
4640  return false;
4641  Success = false;
4642  }
4643  }
4644 
4645  return Success &&
4646  EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
4647 }
4648 
4649 static bool HandleConstructorCall(const Expr *E, const LValue &This,
4650  ArrayRef<const Expr*> Args,
4651  const CXXConstructorDecl *Definition,
4652  EvalInfo &Info, APValue &Result) {
4653  ArgVector ArgValues(Args.size());
4654  if (!EvaluateArgs(Args, ArgValues, Info))
4655  return false;
4656 
4657  return HandleConstructorCall(E, This, ArgValues.data(), Definition,
4658  Info, Result);
4659 }
4660 
4661 //===----------------------------------------------------------------------===//
4662 // Generic Evaluation
4663 //===----------------------------------------------------------------------===//
4664 namespace {
4665 
4666 template <class Derived>
4667 class ExprEvaluatorBase
4668  : public ConstStmtVisitor<Derived, bool> {
4669 private:
4670  Derived &getDerived() { return static_cast<Derived&>(*this); }
4671  bool DerivedSuccess(const APValue &V, const Expr *E) {
4672  return getDerived().Success(V, E);
4673  }
4674  bool DerivedZeroInitialization(const Expr *E) {
4675  return getDerived().ZeroInitialization(E);
4676  }
4677 
4678  // Check whether a conditional operator with a non-constant condition is a
4679  // potential constant expression. If neither arm is a potential constant
4680  // expression, then the conditional operator is not either.
4681  template<typename ConditionalOperator>
4682  void CheckPotentialConstantConditional(const ConditionalOperator *E) {
4683  assert(Info.checkingPotentialConstantExpression());
4684 
4685  // Speculatively evaluate both arms.
4687  {
4688  SpeculativeEvaluationRAII Speculate(Info, &Diag);
4689  StmtVisitorTy::Visit(E->getFalseExpr());
4690  if (Diag.empty())
4691  return;
4692  }
4693 
4694  {
4695  SpeculativeEvaluationRAII Speculate(Info, &Diag);
4696  Diag.clear();
4697  StmtVisitorTy::Visit(E->getTrueExpr());
4698  if (Diag.empty())
4699  return;
4700  }
4701 
4702  Error(E, diag::note_constexpr_conditional_never_const);
4703  }
4704 
4705 
4706  template<typename ConditionalOperator>
4707  bool HandleConditionalOperator(const ConditionalOperator *E) {
4708  bool BoolResult;
4709  if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) {
4710  if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) {
4711  CheckPotentialConstantConditional(E);
4712  return false;
4713  }
4714  if (Info.noteFailure()) {
4715  StmtVisitorTy::Visit(E->getTrueExpr());
4716  StmtVisitorTy::Visit(E->getFalseExpr());
4717  }
4718  return false;
4719  }
4720 
4721  Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
4722  return StmtVisitorTy::Visit(EvalExpr);
4723  }
4724 
4725 protected:
4726  EvalInfo &Info;
4727  typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy;
4728  typedef ExprEvaluatorBase ExprEvaluatorBaseTy;
4729 
4730  OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
4731  return Info.CCEDiag(E, D);
4732  }
4733 
4734  bool ZeroInitialization(const Expr *E) { return Error(E); }
4735 
4736 public:
4737  ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {}
4738 
4739  EvalInfo &getEvalInfo() { return Info; }
4740 
4741  /// Report an evaluation error. This should only be called when an error is
4742  /// first discovered. When propagating an error, just return false.
4743  bool Error(const Expr *E, diag::kind D) {
4744  Info.FFDiag(E, D);
4745  return false;
4746  }
4747  bool Error(const Expr *E) {
4748  return Error(E, diag::note_invalid_subexpr_in_const_expr);
4749  }
4750 
4751  bool VisitStmt(const Stmt *) {
4752  llvm_unreachable("Expression evaluator should not be called on stmts");
4753  }
4754  bool VisitExpr(const Expr *E) {
4755  return Error(E);
4756  }
4757 
4758  bool VisitConstantExpr(const ConstantExpr *E)
4759  { return StmtVisitorTy::Visit(E->getSubExpr()); }
4760  bool VisitParenExpr(const ParenExpr *E)
4761  { return StmtVisitorTy::Visit(E->getSubExpr()); }
4762  bool VisitUnaryExtension(const UnaryOperator *E)
4763  { return StmtVisitorTy::Visit(E->getSubExpr()); }
4764  bool VisitUnaryPlus(const UnaryOperator *E)
4765  { return StmtVisitorTy::Visit(E->getSubExpr()); }
4766  bool VisitChooseExpr(const ChooseExpr *E)
4767  { return StmtVisitorTy::Visit(E->getChosenSubExpr()); }
4768  bool VisitGenericSelectionExpr(const GenericSelectionExpr *E)
4769  { return StmtVisitorTy::Visit(E->getResultExpr()); }
4770  bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E)
4771  { return StmtVisitorTy::Visit(E->getReplacement()); }
4772  bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) {
4773  TempVersionRAII RAII(*Info.CurrentCall);
4774  return StmtVisitorTy::Visit(E->getExpr());
4775  }
4776  bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) {
4777  TempVersionRAII RAII(*Info.CurrentCall);
4778  // The initializer may not have been parsed yet, or might be erroneous.
4779  if (!E->getExpr())
4780  return Error(E);
4781  return StmtVisitorTy::Visit(E->getExpr());
4782  }
4783  // We cannot create any objects for which cleanups are required, so there is
4784  // nothing to do here; all cleanups must come from unevaluated subexpressions.
4785  bool VisitExprWithCleanups(const ExprWithCleanups *E)
4786  { return StmtVisitorTy::Visit(E->getSubExpr()); }
4787 
4788  bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) {
4789  CCEDiag(E, diag::note_constexpr_invalid_cast) << 0;
4790  return static_cast<Derived*>(this)->VisitCastExpr(E);
4791  }
4792  bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) {
4793  CCEDiag(E, diag::note_constexpr_invalid_cast) << 1;
4794  return static_cast<Derived*>(this)->VisitCastExpr(E);
4795  }
4796 
4797  bool VisitBinaryOperator(const BinaryOperator *E) {
4798  switch (E->getOpcode()) {
4799  default:
4800  return Error(E);
4801 
4802  case BO_Comma:
4803  VisitIgnoredValue(E->getLHS());
4804  return StmtVisitorTy::Visit(E->getRHS());
4805 
4806  case BO_PtrMemD:
4807  case BO_PtrMemI: {
4808  LValue Obj;
4809  if (!HandleMemberPointerAccess(Info, E, Obj))
4810  return false;
4811  APValue Result;
4812  if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result))
4813  return false;
4814  return DerivedSuccess(Result, E);
4815  }
4816  }
4817  }
4818 
4819  bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) {
4820  // Evaluate and cache the common expression. We treat it as a temporary,
4821  // even though it's not quite the same thing.
4822  if (!Evaluate(Info.CurrentCall->createTemporary(E->getOpaqueValue(), false),
4823  Info, E->getCommon()))
4824  return false;
4825 
4826  return HandleConditionalOperator(E);
4827  }
4828 
4829  bool VisitConditionalOperator(const ConditionalOperator *E) {
4830  bool IsBcpCall = false;
4831  // If the condition (ignoring parens) is a __builtin_constant_p call,
4832  // the result is a constant expression if it can be folded without
4833  // side-effects. This is an important GNU extension. See GCC PR38377
4834  // for discussion.
4835  if (const CallExpr *CallCE =
4836  dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts()))
4837  if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
4838  IsBcpCall = true;
4839 
4840  // Always assume __builtin_constant_p(...) ? ... : ... is a potential
4841  // constant expression; we can't check whether it's potentially foldable.
4842  if (Info.checkingPotentialConstantExpression() && IsBcpCall)
4843  return false;
4844 
4845  FoldConstant Fold(Info, IsBcpCall);
4846  if (!HandleConditionalOperator(E)) {
4847  Fold.keepDiagnostics();
4848  return false;
4849  }
4850 
4851  return true;
4852  }
4853 
4854  bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) {
4855  if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E))
4856  return DerivedSuccess(*Value, E);
4857 
4858  const Expr *Source = E->getSourceExpr();
4859  if (!Source)
4860  return Error(E);
4861  if (Source == E) { // sanity checking.
4862  assert(0 && "OpaqueValueExpr recursively refers to itself");
4863  return Error(E);
4864  }
4865  return StmtVisitorTy::Visit(Source);
4866  }
4867 
4868  bool VisitCallExpr(const CallExpr *E) {
4869  APValue Result;
4870  if (!handleCallExpr(E, Result, nullptr))
4871  return false;
4872  return DerivedSuccess(Result, E);
4873  }
4874 
4875  bool handleCallExpr(const CallExpr *E, APValue &Result,
4876  const LValue *ResultSlot) {
4877  const Expr *Callee = E->getCallee()->IgnoreParens();
4878  QualType CalleeType = Callee->getType();
4879 
4880  const FunctionDecl *FD = nullptr;
4881  LValue *This = nullptr, ThisVal;
4882  auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs());
4883  bool HasQualifier = false;
4884 
4885  // Extract function decl and 'this' pointer from the callee.
4886  if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) {
4887  const ValueDecl *Member = nullptr;
4888  if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) {
4889  // Explicit bound member calls, such as x.f() or p->g();
4890  if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal))
4891  return false;
4892  Member = ME->getMemberDecl();
4893  This = &ThisVal;
4894  HasQualifier = ME->hasQualifier();
4895  } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) {
4896  // Indirect bound member calls ('.*' or '->*').
4897  Member = HandleMemberPointerAccess(Info, BE, ThisVal, false);
4898  if (!Member) return false;
4899  This = &ThisVal;
4900  } else
4901  return Error(Callee);
4902 
4903  FD = dyn_cast<FunctionDecl>(Member);
4904  if (!FD)
4905  return Error(Callee);
4906  } else if (CalleeType->isFunctionPointerType()) {
4907  LValue Call;
4908  if (!EvaluatePointer(Callee, Call, Info))
4909  return false;
4910 
4911  if (!Call.getLValueOffset().isZero())
4912  return Error(Callee);
4913  FD = dyn_cast_or_null<FunctionDecl>(
4914  Call.getLValueBase().dyn_cast<const ValueDecl*>());
4915  if (!FD)
4916  return Error(Callee);
4917  // Don't call function pointers which have been cast to some other type.
4918  // Per DR (no number yet), the caller and callee can differ in noexcept.
4919  if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec(
4920  CalleeType->getPointeeType(), FD->getType())) {
4921  return Error(E);
4922  }
4923 
4924  // Overloaded operator calls to member functions are represented as normal
4925  // calls with '*this' as the first argument.
4926  const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
4927  if (MD && !MD->isStatic()) {
4928  // FIXME: When selecting an implicit conversion for an overloaded
4929  // operator delete, we sometimes try to evaluate calls to conversion
4930  // operators without a 'this' parameter!
4931  if (Args.empty())
4932  return Error(E);
4933 
4934  if (!EvaluateObjectArgument(Info, Args[0], ThisVal))
4935  return false;
4936  This = &ThisVal;
4937  Args = Args.slice(1);
4938  } else if (MD && MD->isLambdaStaticInvoker()) {
4939  // Map the static invoker for the lambda back to the call operator.
4940  // Conveniently, we don't have to slice out the 'this' argument (as is
4941  // being done for the non-static case), since a static member function
4942  // doesn't have an implicit argument passed in.
4943  const CXXRecordDecl *ClosureClass = MD->getParent();
4944  assert(
4945  ClosureClass->captures_begin() == ClosureClass->captures_end() &&
4946  "Number of captures must be zero for conversion to function-ptr");
4947 
4948  const CXXMethodDecl *LambdaCallOp =
4949  ClosureClass->getLambdaCallOperator();
4950 
4951  // Set 'FD', the function that will be called below, to the call
4952  // operator. If the closure object represents a generic lambda, find
4953  // the corresponding specialization of the call operator.
4954 
4955  if (ClosureClass->isGenericLambda()) {
4956  assert(MD->isFunctionTemplateSpecialization() &&
4957  "A generic lambda's static-invoker function must be a "
4958  "template specialization");
4960  FunctionTemplateDecl *CallOpTemplate =
4961  LambdaCallOp->getDescribedFunctionTemplate();
4962  void *InsertPos = nullptr;
4963  FunctionDecl *CorrespondingCallOpSpecialization =
4964  CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
4965  assert(CorrespondingCallOpSpecialization &&
4966  "We must always have a function call operator specialization "
4967  "that corresponds to our static invoker specialization");
4968  FD = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
4969  } else
4970  FD = LambdaCallOp;
4971  }
4972 
4973 
4974  } else
4975  return Error(E);
4976 
4977  if (This && !This->checkSubobject(Info, E, CSK_This))
4978  return false;
4979 
4980  // DR1358 allows virtual constexpr functions in some cases. Don't allow
4981  // calls to such functions in constant expressions.
4982  if (This && !HasQualifier &&
4983  isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isVirtual())
4984  return Error(E, diag::note_constexpr_virtual_call);
4985 
4986  const FunctionDecl *Definition = nullptr;
4987  Stmt *Body = FD->getBody(Definition);
4988 
4989  if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) ||
4990  !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, Info,
4991  Result, ResultSlot))
4992  return false;
4993 
4994  return true;
4995  }
4996 
4997  bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
4998  return StmtVisitorTy::Visit(E->getInitializer());
4999  }
5000  bool VisitInitListExpr(const InitListExpr *E) {
5001  if (E->getNumInits() == 0)
5002  return DerivedZeroInitialization(E);
5003  if (E->getNumInits() == 1)
5004  return StmtVisitorTy::Visit(E->getInit(0));
5005  return Error(E);
5006  }
5007  bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
5008  return DerivedZeroInitialization(E);
5009  }
5010  bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) {
5011  return DerivedZeroInitialization(E);
5012  }
5013  bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) {
5014  return DerivedZeroInitialization(E);
5015  }
5016 
5017  /// A member expression where the object is a prvalue is itself a prvalue.
5018  bool VisitMemberExpr(const MemberExpr *E) {
5019  assert(!E->isArrow() && "missing call to bound member function?");
5020 
5021  APValue Val;
5022  if (!Evaluate(Val, Info, E->getBase()))
5023  return false;
5024 
5025  QualType BaseTy = E->getBase()->getType();
5026 
5027  const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl());
5028  if (!FD) return Error(E);
5029  assert(!FD->getType()->isReferenceType() && "prvalue reference?");
5030  assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
5031  FD->getParent()->getCanonicalDecl() && "record / field mismatch");
5032 
5033  CompleteObject Obj(&Val, BaseTy, true);
5034  SubobjectDesignator Designator(BaseTy);
5035  Designator.addDeclUnchecked(FD);
5036 
5037  APValue Result;
5038  return extractSubobject(Info, E, Obj, Designator, Result) &&
5039  DerivedSuccess(Result, E);
5040  }
5041 
5042  bool VisitCastExpr(const CastExpr *E) {
5043  switch (E->getCastKind()) {
5044  default:
5045  break;
5046 
5047  case CK_AtomicToNonAtomic: {
5048  APValue AtomicVal;
5049  // This does not need to be done in place even for class/array types:
5050  // atomic-to-non-atomic conversion implies copying the object
5051  // representation.
5052  if (!Evaluate(AtomicVal, Info, E->getSubExpr()))
5053  return false;
5054  return DerivedSuccess(AtomicVal, E);
5055  }
5056 
5057  case CK_NoOp:
5058  case CK_UserDefinedConversion:
5059  return StmtVisitorTy::Visit(E->getSubExpr());
5060 
5061  case CK_LValueToRValue: {
5062  LValue LVal;
5063  if (!EvaluateLValue(E->getSubExpr(), LVal, Info))
5064  return false;
5065  APValue RVal;
5066  // Note, we use the subexpression's type in order to retain cv-qualifiers.
5067  if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
5068  LVal, RVal))
5069  return false;
5070  return DerivedSuccess(RVal, E);
5071  }
5072  }
5073 
5074  return Error(E);
5075  }
5076 
5077  bool VisitUnaryPostInc(const UnaryOperator *UO) {
5078  return VisitUnaryPostIncDec(UO);
5079  }
5080  bool VisitUnaryPostDec(const UnaryOperator *UO) {
5081  return VisitUnaryPostIncDec(UO);
5082  }
5083  bool VisitUnaryPostIncDec(const UnaryOperator *UO) {
5084  if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5085  return Error(UO);
5086 
5087  LValue LVal;
5088  if (!EvaluateLValue(UO->getSubExpr(), LVal, Info))
5089  return false;
5090  APValue RVal;
5091  if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(),
5092  UO->isIncrementOp(), &RVal))
5093  return false;
5094  return DerivedSuccess(RVal, UO);
5095  }
5096 
5097  bool VisitStmtExpr(const StmtExpr *E) {
5098  // We will have checked the full-expressions inside the statement expression
5099  // when they were completed, and don't need to check them again now.
5100  if (Info.checkingForOverflow())
5101  return Error(E);
5102 
5103  BlockScopeRAII Scope(Info);
5104  const CompoundStmt *CS = E->getSubStmt();
5105  if (CS->body_empty())
5106  return true;
5107 
5109  BE = CS->body_end();
5110  /**/; ++BI) {
5111  if (BI + 1 == BE) {
5112  const Expr *FinalExpr = dyn_cast<Expr>(*BI);
5113  if (!FinalExpr) {
5114  Info.FFDiag((*BI)->getBeginLoc(),
5115  diag::note_constexpr_stmt_expr_unsupported);
5116  return false;
5117  }
5118  return this->Visit(FinalExpr);
5119  }
5120 
5121  APValue ReturnValue;
5122  StmtResult Result = { ReturnValue, nullptr };
5123  EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI);
5124  if (ESR != ESR_Succeeded) {
5125  // FIXME: If the statement-expression terminated due to 'return',
5126  // 'break', or 'continue', it would be nice to propagate that to
5127  // the outer statement evaluation rather than bailing out.
5128  if (ESR != ESR_Failed)
5129  Info.FFDiag((*BI)->getBeginLoc(),
5130  diag::note_constexpr_stmt_expr_unsupported);
5131  return false;
5132  }
5133  }
5134 
5135  llvm_unreachable("Return from function from the loop above.");
5136  }
5137 
5138  /// Visit a value which is evaluated, but whose value is ignored.
5139  void VisitIgnoredValue(const Expr *E) {
5140  EvaluateIgnoredValue(Info, E);
5141  }
5142 
5143  /// Potentially visit a MemberExpr's base expression.
5144  void VisitIgnoredBaseExpression(const Expr *E) {
5145  // While MSVC doesn't evaluate the base expression, it does diagnose the
5146  // presence of side-effecting behavior.
5147  if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx))
5148  return;
5149  VisitIgnoredValue(E);
5150  }
5151 };
5152 
5153 } // namespace
5154 
5155 //===----------------------------------------------------------------------===//
5156 // Common base class for lvalue and temporary evaluation.
5157 //===----------------------------------------------------------------------===//
5158 namespace {
5159 template<class Derived>
5160 class LValueExprEvaluatorBase
5161  : public ExprEvaluatorBase<Derived> {
5162 protected:
5163  LValue &Result;
5164  bool InvalidBaseOK;
5165  typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy;
5166  typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy;
5167 
5168  bool Success(APValue::LValueBase B) {
5169  Result.set(B);
5170  return true;
5171  }
5172 
5173  bool evaluatePointer(const Expr *E, LValue &Result) {
5174  return EvaluatePointer(E, Result, this->Info, InvalidBaseOK);
5175  }
5176 
5177 public:
5178  LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK)
5179  : ExprEvaluatorBaseTy(Info), Result(Result),
5180  InvalidBaseOK(InvalidBaseOK) {}
5181 
5182  bool Success(const APValue &V, const Expr *E) {
5183  Result.setFrom(this->Info.Ctx, V);
5184  return true;
5185  }
5186 
5187  bool VisitMemberExpr(const MemberExpr *E) {
5188  // Handle non-static data members.
5189  QualType BaseTy;
5190  bool EvalOK;
5191  if (E->isArrow()) {
5192  EvalOK = evaluatePointer(E->getBase(), Result);
5193  BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType();
5194  } else if (E->getBase()->isRValue()) {
5195  assert(E->getBase()->getType()->isRecordType());
5196  EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info);
5197  BaseTy = E->getBase()->getType();
5198  } else {
5199  EvalOK = this->Visit(E->getBase());
5200  BaseTy = E->getBase()->getType();
5201  }
5202  if (!EvalOK) {
5203  if (!InvalidBaseOK)
5204  return false;
5205  Result.setInvalid(E);
5206  return true;
5207  }
5208 
5209  const ValueDecl *MD = E->getMemberDecl();
5210  if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) {
5211  assert(BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() ==
5212  FD->getParent()->getCanonicalDecl() && "record / field mismatch");
5213  (void)BaseTy;
5214  if (!HandleLValueMember(this->Info, E, Result, FD))
5215  return false;
5216  } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) {
5217  if (!HandleLValueIndirectMember(this->Info, E, Result, IFD))
5218  return false;
5219  } else
5220  return this->Error(E);
5221 
5222  if (MD->getType()->isReferenceType()) {
5223  APValue RefValue;
5224  if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result,
5225  RefValue))
5226  return false;
5227  return Success(RefValue, E);
5228  }
5229  return true;
5230  }
5231 
5232  bool VisitBinaryOperator(const BinaryOperator *E) {
5233  switch (E->getOpcode()) {
5234  default:
5235  return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
5236 
5237  case BO_PtrMemD:
5238  case BO_PtrMemI:
5239  return HandleMemberPointerAccess(this->Info, E, Result);
5240  }
5241  }
5242 
5243  bool VisitCastExpr(const CastExpr *E) {
5244  switch (E->getCastKind()) {
5245  default:
5246  return ExprEvaluatorBaseTy::VisitCastExpr(E);
5247 
5248  case CK_DerivedToBase:
5249  case CK_UncheckedDerivedToBase:
5250  if (!this->Visit(E->getSubExpr()))
5251  return false;
5252 
5253  // Now figure out the necessary offset to add to the base LV to get from
5254  // the derived class to the base class.
5255  return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(),
5256  Result);
5257  }
5258  }
5259 };
5260 }
5261 
5262 //===----------------------------------------------------------------------===//
5263 // LValue Evaluation
5264 //
5265 // This is used for evaluating lvalues (in C and C++), xvalues (in C++11),
5266 // function designators (in C), decl references to void objects (in C), and
5267 // temporaries (if building with -Wno-address-of-temporary).
5268 //
5269 // LValue evaluation produces values comprising a base expression of one of the
5270 // following types:
5271 // - Declarations
5272 // * VarDecl
5273 // * FunctionDecl
5274 // - Literals
5275 // * CompoundLiteralExpr in C (and in global scope in C++)
5276 // * StringLiteral
5277 // * CXXTypeidExpr
5278 // * PredefinedExpr
5279 // * ObjCStringLiteralExpr
5280 // * ObjCEncodeExpr
5281 // * AddrLabelExpr
5282 // * BlockExpr
5283 // * CallExpr for a MakeStringConstant builtin
5284 // - Locals and temporaries
5285 // * MaterializeTemporaryExpr
5286 // * Any Expr, with a CallIndex indicating the function in which the temporary
5287 // was evaluated, for cases where the MaterializeTemporaryExpr is missing
5288 // from the AST (FIXME).
5289 // * A MaterializeTemporaryExpr that has static storage duration, with no
5290 // CallIndex, for a lifetime-extended temporary.
5291 // plus an offset in bytes.
5292 //===----------------------------------------------------------------------===//
5293 namespace {
5294 class LValueExprEvaluator
5295  : public LValueExprEvaluatorBase<LValueExprEvaluator> {
5296 public:
5297  LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) :
5298  LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {}
5299 
5300  bool VisitVarDecl(const Expr *E, const VarDecl *VD);
5301  bool VisitUnaryPreIncDec(const UnaryOperator *UO);
5302 
5303  bool VisitDeclRefExpr(const DeclRefExpr *E);
5304  bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); }
5305  bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E);
5306  bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
5307  bool VisitMemberExpr(const MemberExpr *E);
5308  bool VisitStringLiteral(const StringLiteral *E) { return Success(E); }
5309  bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); }
5310  bool VisitCXXTypeidExpr(const CXXTypeidExpr *E);
5311  bool VisitCXXUuidofExpr(const CXXUuidofExpr *E);
5312  bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E);
5313  bool VisitUnaryDeref(const UnaryOperator *E);
5314  bool VisitUnaryReal(const UnaryOperator *E);
5315  bool VisitUnaryImag(const UnaryOperator *E);
5316  bool VisitUnaryPreInc(const UnaryOperator *UO) {
5317  return VisitUnaryPreIncDec(UO);
5318  }
5319  bool VisitUnaryPreDec(const UnaryOperator *UO) {
5320  return VisitUnaryPreIncDec(UO);
5321  }
5322  bool VisitBinAssign(const BinaryOperator *BO);
5323  bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO);
5324 
5325  bool VisitCastExpr(const CastExpr *E) {
5326  switch (E->getCastKind()) {
5327  default:
5328  return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
5329 
5330  case CK_LValueBitCast:
5331  this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
5332  if (!Visit(E->getSubExpr()))
5333  return false;
5334  Result.Designator.setInvalid();
5335  return true;
5336 
5337  case CK_BaseToDerived:
5338  if (!Visit(E->getSubExpr()))
5339  return false;
5340  return HandleBaseToDerivedCast(Info, E, Result);
5341  }
5342  }
5343 };
5344 } // end anonymous namespace
5345 
5346 /// Evaluate an expression as an lvalue. This can be legitimately called on
5347 /// expressions which are not glvalues, in three cases:
5348 /// * function designators in C, and
5349 /// * "extern void" objects
5350 /// * @selector() expressions in Objective-C
5351 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
5352  bool InvalidBaseOK) {
5353  assert(E->isGLValue() || E->getType()->isFunctionType() ||
5354  E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E));
5355  return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
5356 }
5357 
5358 bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
5359  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl()))
5360  return Success(FD);
5361  if (const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl()))
5362  return VisitVarDecl(E, VD);
5363  if (const BindingDecl *BD = dyn_cast<BindingDecl>(E->getDecl()))
5364  return Visit(BD->getBinding());
5365  return Error(E);
5366 }
5367 
5368 
5369 bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
5370 
5371  // If we are within a lambda's call operator, check whether the 'VD' referred
5372  // to within 'E' actually represents a lambda-capture that maps to a
5373  // data-member/field within the closure object, and if so, evaluate to the
5374  // field or what the field refers to.
5375  if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee) &&
5376  isa<DeclRefExpr>(E) &&
5377  cast<DeclRefExpr>(E)->refersToEnclosingVariableOrCapture()) {
5378  // We don't always have a complete capture-map when checking or inferring if
5379  // the function call operator meets the requirements of a constexpr function
5380  // - but we don't need to evaluate the captures to determine constexprness
5381  // (dcl.constexpr C++17).
5382  if (Info.checkingPotentialConstantExpression())
5383  return false;
5384 
5385  if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) {
5386  // Start with 'Result' referring to the complete closure object...
5387  Result = *Info.CurrentCall->This;
5388  // ... then update it to refer to the field of the closure object
5389  // that represents the capture.
5390  if (!HandleLValueMember(Info, E, Result, FD))
5391  return false;
5392  // And if the field is of reference type, update 'Result' to refer to what
5393  // the field refers to.
5394  if (FD->getType()->isReferenceType()) {
5395  APValue RVal;
5396  if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result,
5397  RVal))
5398  return false;
5399  Result.setFrom(Info.Ctx, RVal);
5400  }
5401  return true;
5402  }
5403  }
5404  CallStackFrame *Frame = nullptr;
5405  if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) {
5406  // Only if a local variable was declared in the function currently being
5407  // evaluated, do we expect to be able to find its value in the current
5408  // frame. (Otherwise it was likely declared in an enclosing context and
5409  // could either have a valid evaluatable value (for e.g. a constexpr
5410  // variable) or be ill-formed (and trigger an appropriate evaluation
5411  // diagnostic)).
5412  if (Info.CurrentCall->Callee &&
5413  Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
5414  Frame = Info.CurrentCall;
5415  }
5416  }
5417 
5418  if (!VD->getType()->isReferenceType()) {
5419  if (Frame) {
5420  Result.set({VD, Frame->Index,
5421  Info.CurrentCall->getCurrentTemporaryVersion(VD)});
5422  return true;
5423  }
5424  return Success(VD);
5425  }
5426 
5427  APValue *V;
5428  if (!evaluateVarDeclInit(Info, E, VD, Frame, V, nullptr))
5429  return false;
5430  if (V->isUninit()) {
5431  if (!Info.checkingPotentialConstantExpression())
5432  Info.FFDiag(E, diag::note_constexpr_use_uninit_reference);
5433  return false;
5434  }
5435  return Success(*V, E);
5436 }
5437 
5438 bool LValueExprEvaluator::VisitMaterializeTemporaryExpr(
5439  const MaterializeTemporaryExpr *E) {
5440  // Walk through the expression to find the materialized temporary itself.
5441  SmallVector<const Expr *, 2> CommaLHSs;
5443  const Expr *Inner = E->GetTemporaryExpr()->
5444  skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
5445 
5446  // If we passed any comma operators, evaluate their LHSs.
5447  for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I)
5448  if (!EvaluateIgnoredValue(Info, CommaLHSs[I]))
5449  return false;
5450 
5451  // A materialized temporary with static storage duration can appear within the
5452  // result of a constant expression evaluation, so we need to preserve its
5453  // value for use outside this evaluation.
5454  APValue *Value;
5455  if (E->getStorageDuration() == SD_Static) {
5456  Value = Info.Ctx.getMaterializedTemporaryValue(E, true);
5457  *Value = APValue();
5458  Result.set(E);
5459  } else {
5461  *Info.CurrentCall);
5462  }
5463 
5464  QualType Type = Inner->getType();
5465 
5466  // Materialize the temporary itself.
5467  if (!EvaluateInPlace(*Value, Info, Result, Inner) ||
5468  (E->getStorageDuration() == SD_Static &&
5469  !CheckConstantExpression(Info, E->getExprLoc(), Type, *Value))) {
5470  *Value = APValue();
5471  return false;
5472  }
5473 
5474  // Adjust our lvalue to refer to the desired subobject.
5475  for (unsigned I = Adjustments.size(); I != 0; /**/) {
5476  --I;
5477  switch (Adjustments[I].Kind) {
5479  if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath,
5480  Type, Result))
5481  return false;
5482  Type = Adjustments[I].DerivedToBase.BasePath->getType();
5483  break;
5484 
5486  if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field))
5487  return false;
5488  Type = Adjustments[I].Field->getType();
5489  break;
5490 
5492  if (!HandleMemberPointerAccess(this->Info, Type, Result,
5493  Adjustments[I].Ptr.RHS))
5494  return false;
5495  Type = Adjustments[I].Ptr.MPT->getPointeeType();
5496  break;
5497  }
5498  }
5499 
5500  return true;
5501 }
5502 
5503 bool
5504 LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
5505  assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) &&
5506  "lvalue compound literal in c++?");
5507  // Defer visiting the literal until the lvalue-to-rvalue conversion. We can
5508  // only see this when folding in C, so there's no standard to follow here.
5509  return Success(E);
5510 }
5511 
5512 bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) {
5513  if (!E->isPotentiallyEvaluated())
5514  return Success(E);
5515 
5516  Info.FFDiag(E, diag::note_constexpr_typeid_polymorphic)
5517  << E->getExprOperand()->getType()
5518  << E->getExprOperand()->getSourceRange();
5519  return false;
5520 }
5521 
5522 bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) {
5523  return Success(E);
5524 }
5525 
5526 bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
5527  // Handle static data members.
5528  if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) {
5529  VisitIgnoredBaseExpression(E->getBase());
5530  return VisitVarDecl(E, VD);
5531  }
5532 
5533  // Handle static member functions.
5534  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) {
5535  if (MD->isStatic()) {
5536  VisitIgnoredBaseExpression(E->getBase());
5537  return Success(MD);
5538  }
5539  }
5540 
5541  // Handle non-static data members.
5542  return LValueExprEvaluatorBaseTy::VisitMemberExpr(E);
5543 }
5544 
5545 bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
5546  // FIXME: Deal with vectors as array subscript bases.
5547  if (E->getBase()->getType()->isVectorType())
5548  return Error(E);
5549 
5550  bool Success = true;
5551  if (!evaluatePointer(E->getBase(), Result)) {
5552  if (!Info.noteFailure())
5553  return false;
5554  Success = false;
5555  }
5556 
5557  APSInt Index;
5558  if (!EvaluateInteger(E->getIdx(), Index, Info))
5559  return false;
5560 
5561  return Success &&
5562  HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index);
5563 }
5564 
5565 bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) {
5566  return evaluatePointer(E->getSubExpr(), Result);
5567 }
5568 
5569 bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
5570  if (!Visit(E->getSubExpr()))
5571  return false;
5572  // __real is a no-op on scalar lvalues.
5573  if (E->getSubExpr()->getType()->isAnyComplexType())
5574  HandleLValueComplexElement(Info, E, Result, E->getType(), false);
5575  return true;
5576 }
5577 
5578 bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
5579  assert(E->getSubExpr()->getType()->isAnyComplexType() &&
5580  "lvalue __imag__ on scalar?");
5581  if (!Visit(E->getSubExpr()))
5582  return false;
5583  HandleLValueComplexElement(Info, E, Result, E->getType(), true);
5584  return true;
5585 }
5586 
5587 bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) {
5588  if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5589  return Error(UO);
5590 
5591  if (!this->Visit(UO->getSubExpr()))
5592  return false;
5593 
5594  return handleIncDec(
5595  this->Info, UO, Result, UO->getSubExpr()->getType(),
5596  UO->isIncrementOp(), nullptr);
5597 }
5598 
5599 bool LValueExprEvaluator::VisitCompoundAssignOperator(
5600  const CompoundAssignOperator *CAO) {
5601  if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5602  return Error(CAO);
5603 
5604  APValue RHS;
5605 
5606  // The overall lvalue result is the result of evaluating the LHS.
5607  if (!this->Visit(CAO->getLHS())) {
5608  if (Info.noteFailure())
5609  Evaluate(RHS, this->Info, CAO->getRHS());
5610  return false;
5611  }
5612 
5613  if (!Evaluate(RHS, this->Info, CAO->getRHS()))
5614  return false;
5615 
5616  return handleCompoundAssignment(
5617  this->Info, CAO,
5618  Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(),
5619  CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS);
5620 }
5621 
5622 bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) {
5623  if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
5624  return Error(E);
5625 
5626  APValue NewVal;
5627 
5628  if (!this->Visit(E->getLHS())) {
5629  if (Info.noteFailure())
5630  Evaluate(NewVal, this->Info, E->getRHS());
5631  return false;
5632  }
5633 
5634  if (!Evaluate(NewVal, this->Info, E->getRHS()))
5635  return false;
5636 
5637  return handleAssignment(this->Info, E, Result, E->getLHS()->getType(),
5638  NewVal);
5639 }
5640 
5641 //===----------------------------------------------------------------------===//
5642 // Pointer Evaluation
5643 //===----------------------------------------------------------------------===//
5644 
5645 /// Attempts to compute the number of bytes available at the pointer
5646 /// returned by a function with the alloc_size attribute. Returns true if we
5647 /// were successful. Places an unsigned number into `Result`.
5648 ///
5649 /// This expects the given CallExpr to be a call to a function with an
5650 /// alloc_size attribute.
5652  const CallExpr *Call,
5653  llvm::APInt &Result) {
5654  const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call);
5655 
5656  assert(AllocSize && AllocSize->getElemSizeParam().isValid());
5657  unsigned SizeArgNo = AllocSize->getElemSizeParam().getASTIndex();
5658  unsigned BitsInSizeT = Ctx.getTypeSize(Ctx.getSizeType());
5659  if (Call->getNumArgs() <= SizeArgNo)
5660  return false;
5661 
5662  auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) {
5664  if (!E->EvaluateAsInt(ExprResult, Ctx, Expr::SE_AllowSideEffects))
5665  return false;
5666  Into = ExprResult.Val.getInt();
5667  if (Into.isNegative() || !Into.isIntN(BitsInSizeT))
5668  return false;
5669  Into = Into.zextOrSelf(BitsInSizeT);
5670  return true;
5671  };
5672 
5673  APSInt SizeOfElem;
5674  if (!EvaluateAsSizeT(Call->getArg(SizeArgNo), SizeOfElem))
5675  return false;
5676 
5677  if (!AllocSize->getNumElemsParam().isValid()) {
5678  Result = std::move(SizeOfElem);
5679  return true;
5680  }
5681 
5682  APSInt NumberOfElems;
5683  unsigned NumArgNo = AllocSize->getNumElemsParam().getASTIndex();
5684  if (!EvaluateAsSizeT(Call->getArg(NumArgNo), NumberOfElems))
5685  return false;
5686 
5687  bool Overflow;
5688  llvm::APInt BytesAvailable = SizeOfElem.umul_ov(NumberOfElems, Overflow);
5689  if (Overflow)
5690  return false;
5691 
5692  Result = std::move(BytesAvailable);
5693  return true;
5694 }
5695 
5696 /// Convenience function. LVal's base must be a call to an alloc_size
5697 /// function.
5699  const LValue &LVal,
5700  llvm::APInt &Result) {
5701  assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
5702  "Can't get the size of a non alloc_size function");
5703  const auto *Base = LVal.getLValueBase().get<const Expr *>();
5704  const CallExpr *CE = tryUnwrapAllocSizeCall(Base);
5705  return getBytesReturnedByAllocSizeCall(Ctx, CE, Result);
5706 }
5707 
5708 /// Attempts to evaluate the given LValueBase as the result of a call to
5709 /// a function with the alloc_size attribute. If it was possible to do so, this
5710 /// function will return true, make Result's Base point to said function call,
5711 /// and mark Result's Base as invalid.
5712 static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base,
5713  LValue &Result) {
5714  if (Base.isNull())
5715  return false;
5716 
5717  // Because we do no form of static analysis, we only support const variables.
5718  //
5719  // Additionally, we can't support parameters, nor can we support static
5720  // variables (in the latter case, use-before-assign isn't UB; in the former,
5721  // we have no clue what they'll be assigned to).
5722  const auto *VD =
5723  dyn_cast_or_null<VarDecl>(Base.dyn_cast<const ValueDecl *>());
5724  if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified())
5725  return false;
5726 
5727  const Expr *Init = VD->getAnyInitializer();
5728  if (!Init)
5729  return false;
5730 
5731  const Expr *E = Init->IgnoreParens();
5732  if (!tryUnwrapAllocSizeCall(E))
5733  return false;
5734 
5735  // Store E instead of E unwrapped so that the type of the LValue's base is
5736  // what the user wanted.
5737  Result.setInvalid(E);
5738 
5739  QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType();
5740  Result.addUnsizedArray(Info, E, Pointee);
5741  return true;
5742 }
5743 
5744 namespace {
5745 class PointerExprEvaluator
5746  : public ExprEvaluatorBase<PointerExprEvaluator> {
5747  LValue &Result;
5748  bool InvalidBaseOK;
5749 
5750  bool Success(const Expr *E) {
5751  Result.set(E);
5752  return true;
5753  }
5754 
5755  bool evaluateLValue(const Expr *E, LValue &Result) {
5756  return EvaluateLValue(E, Result, Info, InvalidBaseOK);
5757  }
5758 
5759  bool evaluatePointer(const Expr *E, LValue &Result) {
5760  return EvaluatePointer(E, Result, Info, InvalidBaseOK);
5761  }
5762 
5763  bool visitNonBuiltinCallExpr(const CallExpr *E);
5764 public:
5765 
5766  PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK)
5767  : ExprEvaluatorBaseTy(info), Result(Result),
5768  InvalidBaseOK(InvalidBaseOK) {}
5769 
5770  bool Success(const APValue &V, const Expr *E) {
5771  Result.setFrom(Info.Ctx, V);
5772  return true;
5773  }
5774  bool ZeroInitialization(const Expr *E) {
5775  auto TargetVal = Info.Ctx.getTargetNullPointerValue(E->getType());
5776  Result.setNull(E->getType(), TargetVal);
5777  return true;
5778  }
5779 
5780  bool VisitBinaryOperator(const BinaryOperator *E);
5781  bool VisitCastExpr(const CastExpr* E);
5782  bool VisitUnaryAddrOf(const UnaryOperator *E);
5783  bool VisitObjCStringLiteral(const ObjCStringLiteral *E)
5784  { return Success(E); }
5785  bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) {
5786  if (Info.noteFailure())
5787  EvaluateIgnoredValue(Info, E->getSubExpr());
5788  return Error(E);
5789  }
5790  bool VisitAddrLabelExpr(const AddrLabelExpr *E)
5791  { return Success(E); }
5792  bool VisitCallExpr(const CallExpr *E);
5793  bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
5794  bool VisitBlockExpr(const BlockExpr *E) {
5795  if (!E->getBlockDecl()->hasCaptures())
5796  return Success(E);
5797  return Error(E);
5798  }
5799  bool VisitCXXThisExpr(const CXXThisExpr *E) {
5800  // Can't look at 'this' when checking a potential constant expression.
5801  if (Info.checkingPotentialConstantExpression())
5802  return false;
5803  if (!Info.CurrentCall->This) {
5804  if (Info.getLangOpts().CPlusPlus11)
5805  Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit();
5806  else
5807  Info.FFDiag(E);
5808  return false;
5809  }
5810  Result = *Info.CurrentCall->This;
5811  // If we are inside a lambda's call operator, the 'this' expression refers
5812  // to the enclosing '*this' object (either by value or reference) which is
5813  // either copied into the closure object's field that represents the '*this'
5814  // or refers to '*this'.
5815  if (isLambdaCallOperator(Info.CurrentCall->Callee)) {
5816  // Update 'Result' to refer to the data member/field of the closure object
5817  // that represents the '*this' capture.
5818  if (!HandleLValueMember(Info, E, Result,
5819  Info.CurrentCall->LambdaThisCaptureField))
5820  return false;
5821  // If we captured '*this' by reference, replace the field with its referent.
5822  if (Info.CurrentCall->LambdaThisCaptureField->getType()
5823  ->isPointerType()) {
5824  APValue RVal;
5825  if (!handleLValueToRValueConversion(Info, E, E->getType(), Result,
5826  RVal))
5827  return false;
5828 
5829  Result.setFrom(Info.Ctx, RVal);
5830  }
5831  }
5832  return true;
5833  }
5834 
5835  // FIXME: Missing: @protocol, @selector
5836 };
5837 } // end anonymous namespace
5838 
5839 static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info,
5840  bool InvalidBaseOK) {
5841  assert(E->isRValue() && E->getType()->hasPointerRepresentation());
5842  return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
5843 }
5844 
5845 bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
5846  if (E->getOpcode() != BO_Add &&
5847  E->getOpcode() != BO_Sub)
5848  return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
5849 
5850  const Expr *PExp = E->getLHS();
5851  const Expr *IExp = E->getRHS();
5852  if (IExp->getType()->isPointerType())
5853  std::swap(PExp, IExp);
5854 
5855  bool EvalPtrOK = evaluatePointer(PExp, Result);
5856  if (!EvalPtrOK && !Info.noteFailure())
5857  return false;
5858 
5859  llvm::APSInt Offset;
5860  if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK)
5861  return false;
5862 
5863  if (E->getOpcode() == BO_Sub)
5864  negateAsSigned(Offset);
5865 
5866  QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType();
5867  return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset);
5868 }
5869 
5870 bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
5871  return evaluateLValue(E->getSubExpr(), Result);
5872 }
5873 
5874 bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
5875  const Expr *SubExpr = E->getSubExpr();
5876 
5877  switch (E->getCastKind()) {
5878  default:
5879  break;
5880 
5881  case CK_BitCast:
5882  case CK_CPointerToObjCPointerCast:
5883  case CK_BlockPointerToObjCPointerCast:
5884  case CK_AnyPointerToBlockPointerCast:
5885  case CK_AddressSpaceConversion:
5886  if (!Visit(SubExpr))
5887  return false;
5888  // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are
5889  // permitted in constant expressions in C++11. Bitcasts from cv void* are
5890  // also static_casts, but we disallow them as a resolution to DR1312.
5891  if (!E->getType()->isVoidPointerType()) {
5892  Result.Designator.setInvalid();
5893  if (SubExpr->getType()->isVoidPointerType())
5894  CCEDiag(E, diag::note_constexpr_invalid_cast)
5895  << 3 << SubExpr->getType();
5896  else
5897  CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
5898  }
5899  if (E->getCastKind() == CK_AddressSpaceConversion && Result.IsNullPtr)
5900  ZeroInitialization(E);
5901  return true;
5902 
5903  case CK_DerivedToBase:
5904  case CK_UncheckedDerivedToBase:
5905  if (!evaluatePointer(E->getSubExpr(), Result))
5906  return false;
5907  if (!Result.Base && Result.Offset.isZero())
5908  return true;
5909 
5910  // Now figure out the necessary offset to add to the base LV to get from
5911  // the derived class to the base class.
5912  return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()->
5913  castAs<PointerType>()->getPointeeType(),
5914  Result);
5915 
5916  case CK_BaseToDerived:
5917  if (!Visit(E->getSubExpr()))
5918  return false;
5919  if (!Result.Base && Result.Offset.isZero())
5920  return true;
5921  return HandleBaseToDerivedCast(Info, E, Result);
5922 
5923  case CK_NullToPointer:
5924  VisitIgnoredValue(E->getSubExpr());
5925  return ZeroInitialization(E);
5926 
5927  case CK_IntegralToPointer: {
5928  CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
5929 
5930  APValue Value;
5931  if (!EvaluateIntegerOrLValue(SubExpr, Value, Info))
5932  break;
5933 
5934  if (Value.isInt()) {
5935  unsigned Size = Info.Ctx.getTypeSize(E->getType());
5936  uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue();
5937  Result.Base = (Expr*)nullptr;
5938  Result.InvalidBase = false;
5939  Result.Offset = CharUnits::fromQuantity(N);
5940  Result.Designator.setInvalid();
5941  Result.IsNullPtr = false;
5942  return true;
5943  } else {
5944  // Cast is of an lvalue, no need to change value.
5945  Result.setFrom(Info.Ctx, Value);
5946  return true;
5947  }
5948  }
5949 
5950  case CK_ArrayToPointerDecay: {
5951  if (SubExpr->isGLValue()) {
5952  if (!evaluateLValue(SubExpr, Result))
5953  return false;
5954  } else {
5955  APValue &Value = createTemporary(SubExpr, false, Result,
5956  *Info.CurrentCall);
5957  if (!EvaluateInPlace(Value, Info, Result, SubExpr))
5958  return false;
5959  }
5960  // The result is a pointer to the first element of the array.
5961  auto *AT = Info.Ctx.getAsArrayType(SubExpr->getType());
5962  if (auto *CAT = dyn_cast<ConstantArrayType>(AT))
5963  Result.addArray(Info, E, CAT);
5964  else
5965  Result.addUnsizedArray(Info, E, AT->getElementType());
5966  return true;
5967  }
5968 
5969  case CK_FunctionToPointerDecay:
5970  return evaluateLValue(SubExpr, Result);
5971 
5972  case CK_LValueToRValue: {
5973  LValue LVal;
5974  if (!evaluateLValue(E->getSubExpr(), LVal))
5975  return false;
5976 
5977  APValue RVal;
5978  // Note, we use the subexpression's type in order to retain cv-qualifiers.
5979  if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
5980  LVal, RVal))
5981  return InvalidBaseOK &&
5982  evaluateLValueAsAllocSize(Info, LVal.Base, Result);
5983  return Success(RVal, E);
5984  }
5985  }
5986 
5987  return ExprEvaluatorBaseTy::VisitCastExpr(E);
5988 }
5989