[NFC] AST: Pack ParamDecl bits into intrusive bitfield

Author: davezarzycki

include/swift/AST/Decl.h

@@ -332,6 +332,18 @@ class alignas(1 << DeclAlignInBits) Decl {
     unsigned IsDebuggerVar : 1;
   BITFIELD_END;
 
+  BITFIELD_START(ParamDecl, VarDecl, 1 + NumDefaultArgumentKindBits);
+    /// True if the type is implicitly specified in the source, but this has an
+    /// apparently valid typeRepr.  This is used in accessors, which look like:
+    ///    set (value) {
+    /// but need to get the typeRepr from the property as a whole so Sema can
+    /// resolve the type.
+    unsigned IsTypeLocImplicit : 1;
+
+    /// Information about a symbolic default argument, like #file.
+    unsigned defaultArgumentKind : NumDefaultArgumentKindBits;
+  BITFIELD_END;
+
   BITFIELD_START(EnumElementDecl, ValueDecl, 3);
     /// \brief Whether or not this element directly or indirectly references
     /// the enum type.
@@ -553,6 +565,7 @@ class alignas(1 << DeclAlignInBits) Decl {
     AbstractStorageDeclBitfields AbstractStorageDeclBits;
     AbstractFunctionDeclBitfields AbstractFunctionDeclBits;
     VarDeclBitfields VarDeclBits;
+    ParamDeclBitfields ParamDeclBits;
     EnumElementDeclBitfields EnumElementDeclBits;
     FuncDeclBitfields FuncDeclBits;
     ConstructorDeclBitfields ConstructorDeclBits;
@@ -4570,16 +4583,6 @@ class ParamDecl : public VarDecl {
   /// The default value, if any, along with whether this is varargs.
   llvm::PointerIntPair<StoredDefaultArgument *, 1> DefaultValueAndIsVariadic;
 
-  /// True if the type is implicitly specified in the source, but this has an
-  /// apparently valid typeRepr.  This is used in accessors, which look like:
-  ///    set (value) {
-  /// but need to get the typeRepr from the property as a whole so Sema can
-  /// resolve the type.
-  bool IsTypeLocImplicit = false;
-  
-  /// Information about a symbolic default argument, like #file.
-  DefaultArgumentKind defaultArgumentKind = DefaultArgumentKind::None;
-  
 public:
   ParamDecl(VarDecl::Specifier specifier,
             SourceLoc specifierLoc, SourceLoc argumentNameLoc,
@@ -4606,17 +4609,17 @@ class ParamDecl : public VarDecl {
 
   SourceLoc getSpecifierLoc() const { return SpecifierLoc; }
 
-  bool isTypeLocImplicit() const { return IsTypeLocImplicit; }
-  void setIsTypeLocImplicit(bool val) { IsTypeLocImplicit = val; }
+  bool isTypeLocImplicit() const { return ParamDeclBits.IsTypeLocImplicit; }
+  void setIsTypeLocImplicit(bool val) { ParamDeclBits.IsTypeLocImplicit = val; }
 
-  bool isDefaultArgument() const {
-    return defaultArgumentKind != DefaultArgumentKind::None;
-  }
   DefaultArgumentKind getDefaultArgumentKind() const {
-    return defaultArgumentKind;
+    return static_cast<DefaultArgumentKind>(ParamDeclBits.defaultArgumentKind);
+  }
+  bool isDefaultArgument() const {
+    return getDefaultArgumentKind() != DefaultArgumentKind::None;
   }
   void setDefaultArgumentKind(DefaultArgumentKind K) {
-    defaultArgumentKind = K;
+    ParamDeclBits.defaultArgumentKind = static_cast<unsigned>(K);
   }
 
   Expr *getDefaultValue() const {

include/swift/AST/DefaultArgumentKind.h

@@ -17,6 +17,8 @@
 #ifndef SWIFT_DEFAULTARGUMENTKIND_H
 #define SWIFT_DEFAULTARGUMENTKIND_H
 
+#include <cstdint>
+
 namespace llvm {
 class StringRef;
 }
@@ -26,7 +28,7 @@ namespace swift {
 class Expr;
 
 /// Describes the kind of default argument a tuple pattern element has.
-enum class DefaultArgumentKind : unsigned {
+enum class DefaultArgumentKind : uint8_t {
   /// No default argument.
   None,
   /// A normal default argument.
@@ -51,6 +53,7 @@ enum class DefaultArgumentKind : unsigned {
   /// An empty dictionary literal.
   EmptyDictionary,
 };
+enum { NumDefaultArgumentKindBits = 4 };
 
 /// Retrieve the spelling of this default argument in source code, or
 /// an empty string if it has none.

lib/AST/Decl.cpp

@@ -4296,6 +4296,9 @@ ParamDecl::ParamDecl(Specifier specifier,
   SpecifierLoc(specifierLoc) {
     assert(specifier != Specifier::Var &&
            "'var' cannot appear on parameters; you meant 'inout'");
+  ParamDeclBits.IsTypeLocImplicit = false;
+  ParamDeclBits.defaultArgumentKind =
+    static_cast<unsigned>(DefaultArgumentKind::None);
 }
 
 /// Clone constructor, allocates a new ParamDecl identical to the first.
@@ -4310,9 +4313,9 @@ ParamDecl::ParamDecl(ParamDecl *PD, bool withTypes)
     ArgumentName(PD->getArgumentName()),
     ArgumentNameLoc(PD->getArgumentNameLoc()),
     SpecifierLoc(PD->getSpecifierLoc()),
-    DefaultValueAndIsVariadic(nullptr, PD->DefaultValueAndIsVariadic.getInt()),
-    IsTypeLocImplicit(PD->IsTypeLocImplicit),
-    defaultArgumentKind(PD->defaultArgumentKind) {
+    DefaultValueAndIsVariadic(nullptr, PD->DefaultValueAndIsVariadic.getInt()) {
+  ParamDeclBits.IsTypeLocImplicit = PD->ParamDeclBits.IsTypeLocImplicit;
+  ParamDeclBits.defaultArgumentKind = PD->ParamDeclBits.defaultArgumentKind;
   typeLoc = PD->getTypeLoc().clone(PD->getASTContext());
   if (!withTypes && typeLoc.getTypeRepr())
     typeLoc.setType(Type());