AST: Store Platform and PlatformAgnostic in AvailableAttr's bits.

Author: tshortli

include/swift/AST/Attr.h

@@ -147,7 +147,13 @@ class DeclAttribute : public AttributeBase {
       Value : 32
     );
 
-    SWIFT_INLINE_BITFIELD(AvailableAttr, DeclAttribute, 1+1,
+    SWIFT_INLINE_BITFIELD(AvailableAttr, DeclAttribute, 8+8+1+1,
+      /// A `PlatformKind` value.
+      Platform : 8,
+
+      /// A `PlatformAgnosticAvailabilityKind` value.
+      PlatformAgnostic : 8,
+
       /// Whether this attribute was spelled `@_spi_available`.
       IsSPI : 1,
 
@@ -700,7 +706,7 @@ enum class AvailableVersionComparison {
 };
 
 /// Describes the platform-agnostic availability of a declaration.
-enum class PlatformAgnosticAvailabilityKind {
+enum class PlatformAgnosticAvailabilityKind : uint8_t {
   /// The associated availability attribute is not platform-agnostic.
   None,
   /// The declaration is deprecated, but can still be used.
@@ -768,14 +774,6 @@ class AvailableAttr : public DeclAttribute {
   /// Indicates where the Obsoleted version was specified.
   const SourceRange ObsoletedRange;
 
-private:
-  /// Indicates if the declaration has platform-agnostic availability.
-  const PlatformAgnosticAvailabilityKind PlatformAgnostic;
-
-  /// The platform that the attribute applies to (may be `none`).
-  const PlatformKind Platform;
-
-public:
   /// Whether this is a language-version-specific entity.
   bool isLanguageVersionSpecific() const;
 
@@ -798,11 +796,14 @@ class AvailableAttr : public DeclAttribute {
   bool isForEmbedded() const { return Bits.AvailableAttr.IsForEmbedded; }
 
   /// Returns the platform that the attribute applies to (may be `none`).
-  PlatformKind getPlatform() const { return Platform; }
+  PlatformKind getPlatform() const {
+    return static_cast<PlatformKind>(Bits.AvailableAttr.Platform);
+  }
 
   /// Returns the platform-agnostic availability.
   PlatformAgnosticAvailabilityKind getPlatformAgnosticAvailability() const {
-    return PlatformAgnostic;
+    return static_cast<PlatformAgnosticAvailabilityKind>(
+        Bits.AvailableAttr.PlatformAgnostic);
   }
 
   /// Determine if a given declaration should be considered unavailable given
@@ -813,18 +814,16 @@ class AvailableAttr : public DeclAttribute {
 
   /// Returns true if the availability applies to a specific
   /// platform.
-  bool hasPlatform() const {
-    return Platform != PlatformKind::none;
-  }
+  bool hasPlatform() const { return getPlatform() != PlatformKind::none; }
 
   /// Returns the string for the platform of the attribute.
   StringRef platformString() const {
-    return swift::platformString(Platform);
+    return swift::platformString(getPlatform());
   }
 
   /// Returns the human-readable string for the platform of the attribute.
   StringRef prettyPlatformString() const {
-    return swift::prettyPlatformString(Platform);
+    return swift::prettyPlatformString(getPlatform());
   }
 
   /// Returns true if this attribute is active given the current platform.

lib/AST/Attr.cpp

@@ -2234,15 +2234,16 @@ AvailableAttr::AvailableAttr(
       Message(Message), Rename(Rename), RenameDecl(RenameDecl),
       INIT_VER_TUPLE(Introduced), IntroducedRange(IntroducedRange),
       INIT_VER_TUPLE(Deprecated), DeprecatedRange(DeprecatedRange),
-      INIT_VER_TUPLE(Obsoleted), ObsoletedRange(ObsoletedRange),
-      PlatformAgnostic(PlatformAgnostic), Platform(Platform) {
+      INIT_VER_TUPLE(Obsoleted), ObsoletedRange(ObsoletedRange) {
+  Bits.AvailableAttr.Platform = static_cast<uint8_t>(Platform);
+  Bits.AvailableAttr.PlatformAgnostic = static_cast<uint8_t>(PlatformAgnostic);
   Bits.AvailableAttr.IsSPI = IsSPI;
 
   if (IsForEmbedded) {
     // FIXME: The IsForEmbedded bit should be removed when library availability
     // conditions are implemented (rdar://138802876)
     Bits.AvailableAttr.IsForEmbedded = true;
-    assert(Platform == PlatformKind::none);
+    assert(getPlatform() == PlatformKind::none);
   }
 }
 
@@ -2279,7 +2280,7 @@ AvailableAttr *AvailableAttr::createForAlternative(
 }
 
 bool AvailableAttr::isActivePlatform(const ASTContext &ctx) const {
-  return isPlatformActive(Platform, ctx.LangOpts);
+  return isPlatformActive(getPlatform(), ctx.LangOpts);
 }
 
 bool BackDeployedAttr::isActivePlatform(const ASTContext &ctx,
@@ -2290,14 +2291,14 @@ bool BackDeployedAttr::isActivePlatform(const ASTContext &ctx,
 AvailableAttr *AvailableAttr::clone(ASTContext &C, bool implicit) const {
   return new (C) AvailableAttr(implicit ? SourceLoc() : AtLoc,
                                implicit ? SourceRange() : getRange(),
-                               Platform, Message, Rename, RenameDecl,
+                               getPlatform(), Message, Rename, RenameDecl,
                                Introduced ? *Introduced : llvm::VersionTuple(),
                                implicit ? SourceRange() : IntroducedRange,
                                Deprecated ? *Deprecated : llvm::VersionTuple(),
                                implicit ? SourceRange() : DeprecatedRange,
                                Obsoleted ? *Obsoleted : llvm::VersionTuple(),
                                implicit ? SourceRange() : ObsoletedRange,
-                               PlatformAgnostic,
+                               getPlatformAgnosticAvailability(),
                                implicit,
                                isSPI(),
                                isForEmbedded());
@@ -2332,10 +2333,10 @@ OriginallyDefinedInAttr *OriginallyDefinedInAttr::clone(ASTContext &C,
 }
 
 bool AvailableAttr::isLanguageVersionSpecific() const {
-  if (PlatformAgnostic ==
+  if (getPlatformAgnosticAvailability() ==
       PlatformAgnosticAvailabilityKind::SwiftVersionSpecific)
     {
-      assert(Platform == PlatformKind::none &&
+      assert(getPlatform() == PlatformKind::none &&
              (Introduced.has_value() ||
               Deprecated.has_value() ||
               Obsoleted.has_value()));
@@ -2345,10 +2346,10 @@ bool AvailableAttr::isLanguageVersionSpecific() const {
 }
 
 bool AvailableAttr::isPackageDescriptionVersionSpecific() const {
-  if (PlatformAgnostic ==
+  if (getPlatformAgnosticAvailability() ==
       PlatformAgnosticAvailabilityKind::PackageDescriptionVersionSpecific)
     {
-      assert(Platform == PlatformKind::none &&
+      assert(getPlatform() == PlatformKind::none &&
              (Introduced.has_value() ||
               Deprecated.has_value() ||
               Obsoleted.has_value()));
@@ -2358,7 +2359,7 @@ bool AvailableAttr::isPackageDescriptionVersionSpecific() const {
 }
 
 bool AvailableAttr::isUnconditionallyUnavailable() const {
-  switch (PlatformAgnostic) {
+  switch (getPlatformAgnosticAvailability()) {
   case PlatformAgnosticAvailabilityKind::None:
   case PlatformAgnosticAvailabilityKind::Deprecated:
   case PlatformAgnosticAvailabilityKind::SwiftVersionSpecific:
@@ -2375,7 +2376,7 @@ bool AvailableAttr::isUnconditionallyUnavailable() const {
 }
 
 bool AvailableAttr::isUnconditionallyDeprecated() const {
-  switch (PlatformAgnostic) {
+  switch (getPlatformAgnosticAvailability()) {
   case PlatformAgnosticAvailabilityKind::None:
   case PlatformAgnosticAvailabilityKind::Unavailable:
   case PlatformAgnosticAvailabilityKind::UnavailableInSwift:
@@ -2392,7 +2393,8 @@ bool AvailableAttr::isUnconditionallyDeprecated() const {
 }
 
 bool AvailableAttr::isNoAsync() const {
-  return PlatformAgnostic == PlatformAgnosticAvailabilityKind::NoAsync;
+  return getPlatformAgnosticAvailability() ==
+         PlatformAgnosticAvailabilityKind::NoAsync;
 }
 
 llvm::VersionTuple AvailableAttr::getActiveVersion(const ASTContext &ctx) const {