[AST] NFC: Use llvm::TrailingObjects for TupleType elements

Author: davezarzycki

include/swift/AST/Types.h

@@ -362,8 +362,13 @@ class alignas(1 << TypeAlignInBits) TypeBase {
 
     /// Whether an element of the tuple is inout.
     unsigned HasInOutElement : 1;
+
+    unsigned : 32 - (NumTypeBaseBits + 1); // unused / padding
+
+    /// The number of elements of the tuple.
+    unsigned Count : 32;
   };
-  NUMBITS(TupleType, NumTypeBaseBits + 1);
+  NUMBITS(TupleType, 64);
 
 #undef NUMBITS
   union {
@@ -1577,8 +1582,9 @@ typedef ArrayRefView<TupleTypeElt,CanType,getCanTupleEltType>
 /// TupleType - A tuple is a parenthesized list of types where each name has an
 /// optional name.
 ///
-class TupleType : public TypeBase, public llvm::FoldingSetNode {
-  const ArrayRef<TupleTypeElt> Elements;
+class TupleType final : public TypeBase, public llvm::FoldingSetNode,
+    private llvm::TrailingObjects<TupleType, TupleTypeElt> {
+  friend TrailingObjects;
 
 public:
   /// get - Return the uniqued tuple type with the specified elements.
@@ -1590,16 +1596,20 @@ class TupleType : public TypeBase, public llvm::FoldingSetNode {
   /// getEmpty - Return the empty tuple type '()'.
   static CanTypeWrapper<TupleType> getEmpty(const ASTContext &C);
 
-  /// getFields - Return the fields of this tuple.
-  ArrayRef<TupleTypeElt> getElements() const { return Elements; }
+  unsigned getNumElements() const { return TupleTypeBits.Count; }
 
-  unsigned getNumElements() const { return Elements.size(); }
+  /// getElements - Return the elements of this tuple.
+  ArrayRef<TupleTypeElt> getElements() const {
+    return {getTrailingObjects<TupleTypeElt>(), getNumElements()};
+  }
 
-  const TupleTypeElt &getElement(unsigned i) const { return Elements[i]; }
+  const TupleTypeElt &getElement(unsigned i) const {
+    return getTrailingObjects<TupleTypeElt>()[i];
+  }
 
   /// getElementType - Return the type of the specified element.
   Type getElementType(unsigned ElementNo) const {
-    return Elements[ElementNo].getType();
+    return getTrailingObjects<TupleTypeElt>()[ElementNo].getType();
   }
 
   TupleEltTypeArrayRef getElementTypes() const {
@@ -1631,7 +1641,7 @@ class TupleType : public TypeBase, public llvm::FoldingSetNode {
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
-    Profile(ID, Elements);
+    Profile(ID, getElements());
   }
   static void Profile(llvm::FoldingSetNodeID &ID, 
                       ArrayRef<TupleTypeElt> Elements);
@@ -1640,8 +1650,11 @@ class TupleType : public TypeBase, public llvm::FoldingSetNode {
   TupleType(ArrayRef<TupleTypeElt> elements, const ASTContext *CanCtx,
             RecursiveTypeProperties properties,
             bool hasInOut)
-     : TypeBase(TypeKind::Tuple, CanCtx, properties), Elements(elements) {
+     : TypeBase(TypeKind::Tuple, CanCtx, properties) {
      TupleTypeBits.HasInOutElement = hasInOut;
+     TupleTypeBits.Count = elements.size();
+     std::uninitialized_copy(elements.begin(), elements.end(),
+                             getTrailingObjects<TupleTypeElt>());
   }
 };
 BEGIN_CAN_TYPE_WRAPPER(TupleType, Type)

lib/AST/ASTContext.cpp

@@ -3077,10 +3077,6 @@ Type TupleType::get(ArrayRef<TupleTypeElt> Fields, const ASTContext &C) {
         = C.Impl.getArena(arena).TupleTypes.FindNodeOrInsertPos(ID,InsertPos))
     return TT;
 
-  // Make a copy of the fields list into ASTContext owned memory.
-  TupleTypeElt *FieldsCopy =
-    C.AllocateCopy<TupleTypeElt>(Fields.begin(), Fields.end(), arena);
-
   bool IsCanonical = true;   // All canonical elts means this is canonical.
   for (const TupleTypeElt &Elt : Fields) {
     if (Elt.getType().isNull() || !Elt.getType()->isCanonical()) {
@@ -3089,11 +3085,12 @@ Type TupleType::get(ArrayRef<TupleTypeElt> Fields, const ASTContext &C) {
     }
   }
 
-  Fields = ArrayRef<TupleTypeElt>(FieldsCopy, Fields.size());
-
-  TupleType *New =
-      new (C, arena) TupleType(Fields, IsCanonical ? &C : nullptr,
-                               properties, hasInOut);
+  // TupleType will copy the fields list into ASTContext owned memory.
+  void *mem = C.Allocate(sizeof(TupleType) +
+                         sizeof(TupleTypeElt) * Fields.size(),
+                         alignof(TupleType), arena);
+  auto New = new (mem) TupleType(Fields, IsCanonical ? &C : nullptr, properties,
+                                 hasInOut);
   C.Impl.getArena(arena).TupleTypes.InsertNode(New, InsertPos);
   return New;
 }

lib/AST/Type.cpp

@@ -2384,8 +2384,8 @@ bool TypeBase::matches(Type other, TypeMatchOptions matchMode,
 /// getNamedElementId - If this tuple has a field with the specified name,
 /// return the field index, otherwise return -1.
 int TupleType::getNamedElementId(Identifier I) const {
-  for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
-    if (Elements[i].getName() == I)
+  for (unsigned i = 0, e = TupleTypeBits.Count; i != e; ++i) {
+    if (getTrailingObjects<TupleTypeElt>()[i].getName() == I)
       return i;
   }
 
@@ -2397,15 +2397,15 @@ int TupleType::getNamedElementId(Identifier I) const {
 /// scalar, return the field number that the scalar is assigned to.  If not,
 /// return -1.
 int TupleType::getElementForScalarInit() const {
-  if (Elements.empty()) return -1;
+  if (TupleTypeBits.Count == 0) return -1;
 
   int FieldWithoutDefault = -1;
-  for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
+  for (unsigned i = 0, e = TupleTypeBits.Count; i != e; ++i) {
     // If we already saw a non-vararg field missing a default value, then we
     // cannot assign a scalar to this tuple.
     if (FieldWithoutDefault != -1) {
       // Vararg fields are okay; they'll just end up being empty.
-      if (Elements[i].isVararg())
+      if (getTrailingObjects<TupleTypeElt>()[i].isVararg())
         continue;
 
       return -1;
@@ -2424,9 +2424,9 @@ int TupleType::getElementForScalarInit() const {
 /// varargs element (i.e., if it is "Int...", this returns Int, not [Int]).
 /// Otherwise, this returns Type().
 Type TupleType::getVarArgsBaseType() const {
-  for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
-    if (Elements[i].isVararg())
-      return Elements[i].getVarargBaseTy();
+  for (unsigned i = 0, e = TupleTypeBits.Count; i != e; ++i) {
+    if (getTrailingObjects<TupleTypeElt>()[i].isVararg())
+      return getTrailingObjects<TupleTypeElt>()[i].getVarargBaseTy();
   }
 
   return Type();