[libSyntax] Store data of RecoredeOrDeferredNode as PointerIntPair

This furthere reduces the size of ParsedRawSyntaxNode, as well as for intermediate data structures using in SyntaxParseActions, improving syntax parsing performance.

Author: ahoppen

include/swift/Parse/ParsedRawSyntaxNode.h

@@ -33,7 +33,6 @@
 
 namespace swift {
 
-typedef const void *OpaqueSyntaxNode;
 class SyntaxParsingContext;
 
 /// Represents a raw syntax node formed by the parser.

include/swift/Parse/SyntaxParseActions.h

@@ -20,6 +20,8 @@
 
 #include "swift/Basic/LLVM.h"
 #include "swift/Basic/SourceLoc.h"
+#include "swift/Subsystems.h"
+#include "llvm/ADT/PointerIntPair.h"
 #include "llvm/Support/Allocator.h"
 
 namespace swift {
@@ -34,8 +36,6 @@ class SourceFileSyntax;
 enum class SyntaxKind : uint16_t;
 }
 
-typedef const void *OpaqueSyntaxNode;
-
 // MARK: - Helper types
 
 /// A syntax node that can either be deferred or recorded. The actual data is
@@ -51,15 +51,14 @@ class RecordedOrDeferredNode {
   };
 
 private:
-  OpaqueSyntaxNode Opaque;
-  Kind NodeKind;
+  llvm::PointerIntPair<OpaqueSyntaxNode, 2, Kind> Data;
 
 public:
   RecordedOrDeferredNode(OpaqueSyntaxNode Node, Kind NodeKind)
-      : Opaque(Node), NodeKind(NodeKind) {}
+      : Data(Node, NodeKind) {}
 
-  OpaqueSyntaxNode getOpaque() const { return Opaque; }
-  Kind getKind() const { return NodeKind; }
+  OpaqueSyntaxNode getOpaque() const { return Data.getPointer(); }
+  Kind getKind() const { return Data.getInt(); }
 };
 
 /// Data returned from \c getDeferredChild. This is enough data to construct

include/swift/Subsystems.h

@@ -53,6 +53,12 @@ namespace swift {
   class IRGenOptions;
   class LangOptions;
   class ModuleDecl;
+  /// A opaque syntax node created by a \c SyntaxParseAction, whose contents
+  /// must be interpreted by the \c SyntaxParseAction which created it.
+  /// Requires the two low bits to be 0, so that it can be stored in an
+  /// \c llvm::PointerIntPair. This is in particular guaranteed for pointers
+  /// to C/C++ objects and for pointers that were generated by Swift and passed
+  /// to the compiler via a C API (in particular \c CLibParseActions ).
   typedef const void *OpaqueSyntaxNode;
   class Parser;
   class SerializationOptions;