[NFC] Refactor ConstantArrayType size storage

clang/include/clang/AST/Type.h

@@ -1689,7 +1689,10 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
 
     /// Whether we have a stored size expression.
     LLVM_PREFERRED_TYPE(bool)
-    unsigned HasStoredSizeExpr : 1;
+    unsigned HasExternalSize : 1;
+
+    LLVM_PREFERRED_TYPE(unsigned)
+    unsigned SizeWidth : 5;
   };
 
   class BuiltinTypeBitfields {
@@ -3181,35 +3184,93 @@ class ArrayType : public Type, public llvm::FoldingSetNode {
 /// Represents the canonical version of C arrays with a specified constant size.
 /// For example, the canonical type for 'int A[4 + 4*100]' is a
 /// ConstantArrayType where the element type is 'int' and the size is 404.
-class ConstantArrayType final
-    : public ArrayType,
-      private llvm::TrailingObjects<ConstantArrayType, const Expr *> {
+class ConstantArrayType final : public ArrayType {
   friend class ASTContext; // ASTContext creates these.
-  friend TrailingObjects;
 
-  llvm::APInt Size; // Allows us to unique the type.
+  struct ExternalSize {
+    ExternalSize(const llvm::APInt &Sz, const Expr *SE)
+        : Size(Sz), SizeExpr(SE) {}
+    llvm::APInt Size; // Allows us to unique the type.
+    const Expr *SizeExpr;
+  };
 
-  ConstantArrayType(QualType et, QualType can, const llvm::APInt &size,
-                    const Expr *sz, ArraySizeModifier sm, unsigned tq)
-      : ArrayType(ConstantArray, et, can, sm, tq, sz), Size(size) {
-    ConstantArrayTypeBits.HasStoredSizeExpr = sz != nullptr;
-    if (ConstantArrayTypeBits.HasStoredSizeExpr) {
-      assert(!can.isNull() && "canonical constant array should not have size");
-      *getTrailingObjects<const Expr*>() = sz;
-    }
+  union {
+    uint64_t Size;
+    ExternalSize *SizePtr;
+  };
+
+  ConstantArrayType(QualType Et, QualType Can, uint64_t Width, uint64_t Sz,
+                    ArraySizeModifier SM, unsigned TQ)
+      : ArrayType(ConstantArray, Et, Can, SM, TQ, nullptr), Size(Sz) {
+    ConstantArrayTypeBits.HasExternalSize = false;
+    ConstantArrayTypeBits.SizeWidth = Width / 8;
+    // The in-structure size stores the size in bytes rather than bits so we
+    // drop the three least significant bits since they're always zero anyways.
+    assert(Width < 0xFF && "Type width in bits must be less than 8 bits");
   }
 
-  unsigned numTrailingObjects(OverloadToken<const Expr*>) const {
-    return ConstantArrayTypeBits.HasStoredSizeExpr;
+  ConstantArrayType(QualType Et, QualType Can, ExternalSize *SzPtr,
+                    ArraySizeModifier SM, unsigned TQ)
+      : ArrayType(ConstantArray, Et, Can, SM, TQ, SzPtr->SizeExpr),
+        SizePtr(SzPtr) {
+    ConstantArrayTypeBits.HasExternalSize = true;
+    ConstantArrayTypeBits.SizeWidth = 0;
+
+    assert((SzPtr->SizeExpr == nullptr || !Can.isNull()) &&
+           "canonical constant array should not have size expression");
   }
 
+  static ConstantArrayType *Create(const ASTContext &Ctx, QualType ET,
+                                   QualType Can, const llvm::APInt &Sz,
+                                   const Expr *SzExpr, ArraySizeModifier SzMod,
+                                   unsigned Qual);
+
 public:
-  const llvm::APInt &getSize() const { return Size; }
+  /// Return the constant array size as an APInt.
+  llvm::APInt getSize() const {
+    return ConstantArrayTypeBits.HasExternalSize
+               ? SizePtr->Size
+               : llvm::APInt(ConstantArrayTypeBits.SizeWidth * 8, Size);
+  }
+
+  /// Return the bit width of the size type.
+  unsigned getSizeBitWidth() const {
+    return ConstantArrayTypeBits.HasExternalSize
+               ? SizePtr->Size.getBitWidth()
+               : static_cast<unsigned>(ConstantArrayTypeBits.SizeWidth * 8);
+  }
+
+  /// Return true if the size is zero.
+  bool isZeroSize() const {
+    return ConstantArrayTypeBits.HasExternalSize ? SizePtr->Size.isZero()
+                                                 : 0 == Size;
+  }
+
+  /// Return the size zero-extended as a uint64_t.
+  uint64_t getZExtSize() const {
+    return ConstantArrayTypeBits.HasExternalSize ? SizePtr->Size.getZExtValue()
+                                                 : Size;
+  }
+
+  /// Return the size sign-extended as a uint64_t.
+  int64_t getSExtSize() const {
+    return ConstantArrayTypeBits.HasExternalSize ? SizePtr->Size.getSExtValue()
+                                                 : static_cast<int64_t>(Size);
+  }
+
+  /// Return the size zero-extended to uint64_t or UINT64_MAX if the value is
+  /// larger than UINT64_MAX.
+  uint64_t getLimitedSize() const {
+    return ConstantArrayTypeBits.HasExternalSize
+               ? SizePtr->Size.getLimitedValue()
+               : Size;
+  }
+
+  /// Return a pointer to the size expression.
   const Expr *getSizeExpr() const {
-    return ConstantArrayTypeBits.HasStoredSizeExpr
-               ? *getTrailingObjects<const Expr *>()
-               : nullptr;
+    return ConstantArrayTypeBits.HasExternalSize ? SizePtr->SizeExpr : nullptr;
   }
+
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
@@ -3226,14 +3287,13 @@ class ConstantArrayType final
   static unsigned getMaxSizeBits(const ASTContext &Context);
 
   void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Ctx) {
-    Profile(ID, Ctx, getElementType(), getSize(), getSizeExpr(),
+    Profile(ID, Ctx, getElementType(), getZExtSize(), getSizeExpr(),
             getSizeModifier(), getIndexTypeCVRQualifiers());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Ctx,
-                      QualType ET, const llvm::APInt &ArraySize,
-                      const Expr *SizeExpr, ArraySizeModifier SizeMod,
-                      unsigned TypeQuals);
+                      QualType ET, uint64_t ArraySize, const Expr *SizeExpr,
+                      ArraySizeModifier SizeMod, unsigned TypeQuals);
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == ConstantArray;

clang/lib/AST/ASTContext.cpp

@@ -1766,7 +1766,7 @@ TypeInfoChars
 static getConstantArrayInfoInChars(const ASTContext &Context,
                                    const ConstantArrayType *CAT) {
   TypeInfoChars EltInfo = Context.getTypeInfoInChars(CAT->getElementType());
-  uint64_t Size = CAT->getSize().getZExtValue();
+  uint64_t Size = CAT->getZExtSize();
   assert((Size == 0 || static_cast<uint64_t>(EltInfo.Width.getQuantity()) <=
               (uint64_t)(-1)/Size) &&
          "Overflow in array type char size evaluation");
@@ -1910,7 +1910,7 @@ TypeInfo ASTContext::getTypeInfoImpl(const Type *T) const {
     // Model non-constant sized arrays as size zero, but track the alignment.
     uint64_t Size = 0;
     if (const auto *CAT = dyn_cast<ConstantArrayType>(T))
-      Size = CAT->getSize().getZExtValue();
+      Size = CAT->getZExtSize();
 
     TypeInfo EltInfo = getTypeInfo(cast<ArrayType>(T)->getElementType());
     assert((Size == 0 || EltInfo.Width <= (uint64_t)(-1) / Size) &&
@@ -3531,8 +3531,8 @@ QualType ASTContext::getConstantArrayType(QualType EltTy,
   ArySize = ArySize.zextOrTrunc(Target->getMaxPointerWidth());
 
   llvm::FoldingSetNodeID ID;
-  ConstantArrayType::Profile(ID, *this, EltTy, ArySize, SizeExpr, ASM,
-                             IndexTypeQuals);
+  ConstantArrayType::Profile(ID, *this, EltTy, ArySize.getZExtValue(), SizeExpr,
+                             ASM, IndexTypeQuals);
 
   void *InsertPos = nullptr;
   if (ConstantArrayType *ATP =
@@ -3556,11 +3556,8 @@ QualType ASTContext::getConstantArrayType(QualType EltTy,
     assert(!NewIP && "Shouldn't be in the map!"); (void)NewIP;
   }
 
-  void *Mem = Allocate(
-      ConstantArrayType::totalSizeToAlloc<const Expr *>(SizeExpr ? 1 : 0),
-      alignof(ConstantArrayType));
-  auto *New = new (Mem)
-    ConstantArrayType(EltTy, Canon, ArySize, SizeExpr, ASM, IndexTypeQuals);
+  auto *New = ConstantArrayType::Create(*this, EltTy, Canon, ArySize, SizeExpr,
+                                        ASM, IndexTypeQuals);
   ConstantArrayTypes.InsertNode(New, InsertPos);
   Types.push_back(New);
   return QualType(New, 0);
@@ -7022,7 +7019,7 @@ uint64_t
 ASTContext::getConstantArrayElementCount(const ConstantArrayType *CA)  const {
   uint64_t ElementCount = 1;
   do {
-    ElementCount *= CA->getSize().getZExtValue();
+    ElementCount *= CA->getZExtSize();
     CA = dyn_cast_or_null<ConstantArrayType>(
       CA->getElementType()->getAsArrayTypeUnsafe());
   } while (CA);
@@ -8345,7 +8342,7 @@ void ASTContext::getObjCEncodingForTypeImpl(QualType T, std::string &S,
       S += '[';
 
       if (const auto *CAT = dyn_cast<ConstantArrayType>(AT))
-        S += llvm::utostr(CAT->getSize().getZExtValue());
+        S += llvm::utostr(CAT->getZExtSize());
       else {
         //Variable length arrays are encoded as a regular array with 0 elements.
         assert((isa<VariableArrayType>(AT) || isa<IncompleteArrayType>(AT)) &&
@@ -10779,7 +10776,7 @@ QualType ASTContext::mergeTypes(QualType LHS, QualType RHS, bool OfBlockPointer,
   {
     const ConstantArrayType* LCAT = getAsConstantArrayType(LHS);
     const ConstantArrayType* RCAT = getAsConstantArrayType(RHS);
-    if (LCAT && RCAT && RCAT->getSize() != LCAT->getSize())
+    if (LCAT && RCAT && RCAT->getZExtSize() != LCAT->getZExtSize())
       return {};
 
     QualType LHSElem = getAsArrayType(LHS)->getElementType();

clang/lib/AST/Decl.cpp

@@ -2840,7 +2840,7 @@ bool VarDecl::hasFlexibleArrayInit(const ASTContext &Ctx) const {
   auto InitTy = Ctx.getAsConstantArrayType(FlexibleInit->getType());
   if (!InitTy)
     return false;
-  return InitTy->getSize() != 0;
+  return !InitTy->isZeroSize();
 }
 
 CharUnits VarDecl::getFlexibleArrayInitChars(const ASTContext &Ctx) const {

clang/lib/AST/ExprConstant.cpp

@@ -209,7 +209,7 @@ namespace {
         IsArray = true;
 
         if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
-          ArraySize = CAT->getSize().getZExtValue();
+          ArraySize = CAT->getZExtSize();
         } else {
           assert(I == 0 && "unexpected unsized array designator");
           FirstEntryIsUnsizedArray = true;
@@ -401,7 +401,7 @@ namespace {
       // This is a most-derived object.
       MostDerivedType = CAT->getElementType();
       MostDerivedIsArrayElement = true;
-      MostDerivedArraySize = CAT->getSize().getZExtValue();
+      MostDerivedArraySize = CAT->getZExtSize();
       MostDerivedPathLength = Entries.size();
     }
     /// Update this designator to refer to the first element within the array of
@@ -3476,7 +3476,7 @@ static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
   QualType CharType = CAT->getElementType();
   assert(CharType->isIntegerType() && "unexpected character type");
 
-  unsigned Elts = CAT->getSize().getZExtValue();
+  unsigned Elts = CAT->getZExtSize();
   Result = APValue(APValue::UninitArray(),
                    std::min(S->getLength(), Elts), Elts);
   APSInt Value(Info.Ctx.getTypeSize(CharType),
@@ -3619,7 +3619,7 @@ static bool CheckArraySize(EvalInfo &Info, const ConstantArrayType *CAT,
                            SourceLocation CallLoc = {}) {
   return Info.CheckArraySize(
       CAT->getSizeExpr() ? CAT->getSizeExpr()->getBeginLoc() : CallLoc,
-      CAT->getNumAddressingBits(Info.Ctx), CAT->getSize().getZExtValue(),
+      CAT->getNumAddressingBits(Info.Ctx), CAT->getZExtSize(),
       /*Diag=*/true);
 }
 
@@ -4908,7 +4908,7 @@ static bool handleDefaultInitValue(QualType T, APValue &Result) {
 
   if (auto *AT =
           dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) {
-    Result = APValue(APValue::UninitArray(), 0, AT->getSize().getZExtValue());
+    Result = APValue(APValue::UninitArray(), 0, AT->getZExtSize());
     if (Result.hasArrayFiller())
       Success &=
           handleDefaultInitValue(AT->getElementType(), Result.getArrayFiller());
@@ -6595,7 +6595,7 @@ static bool HandleDestructionImpl(EvalInfo &Info, SourceRange CallRange,
 
   // For arrays, destroy elements right-to-left.
   if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(T)) {
-    uint64_t Size = CAT->getSize().getZExtValue();
+    uint64_t Size = CAT->getZExtSize();
     QualType ElemT = CAT->getElementType();
 
     if (!CheckArraySize(Info, CAT, CallRange.getBegin()))
@@ -7396,7 +7396,7 @@ class BufferToAPValueConverter {
   }
 
   std::optional<APValue> visit(const ConstantArrayType *Ty, CharUnits Offset) {
-    size_t Size = Ty->getSize().getLimitedValue();
+    size_t Size = Ty->getLimitedSize();
     CharUnits ElementWidth = Info.Ctx.getTypeSizeInChars(Ty->getElementType());
 
     APValue ArrayValue(APValue::UninitArray(), Size, Size);
@@ -9951,7 +9951,7 @@ bool PointerExprEvaluator::VisitCXXNewExpr(const CXXNewExpr *E) {
       assert(CAT && "unexpected type for array initializer");
 
       unsigned Bits =
-          std::max(CAT->getSize().getBitWidth(), ArrayBound.getBitWidth());
+          std::max(CAT->getSizeBitWidth(), ArrayBound.getBitWidth());
       llvm::APInt InitBound = CAT->getSize().zext(Bits);
       llvm::APInt AllocBound = ArrayBound.zext(Bits);
       if (InitBound.ugt(AllocBound)) {
@@ -10410,7 +10410,7 @@ bool RecordExprEvaluator::VisitCXXParenListOrInitListExpr(
 
     if (Field->getType()->isIncompleteArrayType()) {
       if (auto *CAT = Info.Ctx.getAsConstantArrayType(Init->getType())) {
-        if (!CAT->getSize().isZero()) {
+        if (!CAT->isZeroSize()) {
           // Bail out for now. This might sort of "work", but the rest of the
           // code isn't really prepared to handle it.
           Info.FFDiag(Init, diag::note_constexpr_unsupported_flexible_array);
@@ -10554,7 +10554,7 @@ bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
     // End pointer.
     if (!HandleLValueArrayAdjustment(Info, E, Array,
                                      ArrayType->getElementType(),
-                                     ArrayType->getSize().getZExtValue()))
+                                     ArrayType->getZExtSize()))
       return false;
     Array.moveInto(Result.getStructField(1));
   } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType()))
@@ -10996,8 +10996,7 @@ namespace {
         return Error(E);
       }
 
-      Result = APValue(APValue::UninitArray(), 0,
-                       CAT->getSize().getZExtValue());
+      Result = APValue(APValue::UninitArray(), 0, CAT->getZExtSize());
       if (!Result.hasArrayFiller())
         return true;
 
@@ -11122,7 +11121,7 @@ bool ArrayExprEvaluator::VisitCXXParenListOrInitListExpr(
     Filler = Result.getArrayFiller();
 
   unsigned NumEltsToInit = Args.size();
-  unsigned NumElts = CAT->getSize().getZExtValue();
+  unsigned NumElts = CAT->getZExtSize();
 
   // If the initializer might depend on the array index, run it for each
   // array element.
@@ -11180,7 +11179,7 @@ bool ArrayExprEvaluator::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E) {
 
   auto *CAT = cast<ConstantArrayType>(E->getType()->castAsArrayTypeUnsafe());
 
-  uint64_t Elements = CAT->getSize().getZExtValue();
+  uint64_t Elements = CAT->getZExtSize();
   Result = APValue(APValue::UninitArray(), Elements, Elements);
 
   LValue Subobject = This;
@@ -11225,7 +11224,7 @@ bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
   bool HadZeroInit = Value->hasValue();
 
   if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) {
-    unsigned FinalSize = CAT->getSize().getZExtValue();
+    unsigned FinalSize = CAT->getZExtSize();
 
     // Preserve the array filler if we had prior zero-initialization.
     APValue Filler =
@@ -11940,7 +11939,7 @@ static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
         return true;
       const auto *CAT = cast<ConstantArrayType>(Ctx.getAsArrayType(BaseType));
       uint64_t Index = Entry.getAsArrayIndex();
-      if (Index + 1 != CAT->getSize())
+      if (Index + 1 != CAT->getZExtSize())
         return false;
       BaseType = CAT->getElementType();
     } else if (BaseType->isAnyComplexType()) {

clang/lib/AST/Interp/ByteCodeExprGen.cpp

@@ -819,7 +819,7 @@ bool ByteCodeExprGen<Emitter>::VisitImplicitValueInitExpr(const ImplicitValueIni
     const ArrayType *AT = QT->getAsArrayTypeUnsafe();
     assert(AT);
     const auto *CAT = cast<ConstantArrayType>(AT);
-    size_t NumElems = CAT->getSize().getZExtValue();
+    size_t NumElems = CAT->getZExtSize();
     PrimType ElemT = classifyPrim(CAT->getElementType());
 
     for (size_t I = 0; I != NumElems; ++I) {
@@ -992,7 +992,7 @@ bool ByteCodeExprGen<Emitter>::VisitInitListExpr(const InitListExpr *E) {
     if (const Expr *Filler = E->getArrayFiller()) {
       const ConstantArrayType *CAT =
           Ctx.getASTContext().getAsConstantArrayType(E->getType());
-      uint64_t NumElems = CAT->getSize().getZExtValue();
+      uint64_t NumElems = CAT->getZExtSize();
 
       for (; ElementIndex != NumElems; ++ElementIndex) {
         if (!this->visitArrayElemInit(ElementIndex, Filler))
@@ -1318,7 +1318,7 @@ bool ByteCodeExprGen<Emitter>::VisitStringLiteral(const StringLiteral *E) {
 
   // If the initializer string is too long, a diagnostic has already been
   // emitted. Read only the array length from the string literal.
-  unsigned ArraySize = CAT->getSize().getZExtValue();
+  unsigned ArraySize = CAT->getZExtSize();
   unsigned N = std::min(ArraySize, E->getLength());
   size_t CharWidth = E->getCharByteWidth();
 
@@ -1919,7 +1919,7 @@ bool ByteCodeExprGen<Emitter>::VisitCXXConstructExpr(
     const ConstantArrayType *CAT =
         Ctx.getASTContext().getAsConstantArrayType(E->getType());
     assert(CAT);
-    size_t NumElems = CAT->getSize().getZExtValue();
+    size_t NumElems = CAT->getZExtSize();
     const Function *Func = getFunction(E->getConstructor());
     if (!Func || !Func->isConstexpr())
       return false;