Add a [nonoverridden] kind for SILVTable entries.

This will let us track class methods that must exist for pass ordering, interface, or ABI reasons, but which can
be given more efficient runtime representation because they have no overrides.

Author: jckarter

include/swift/SIL/SILVTable.h

@@ -53,6 +53,9 @@ class SILVTable : public llvm::ilist_node<SILVTable>,
     enum Kind : uint8_t {
       /// The vtable entry is for a method defined directly in this class.
       Normal,
+      /// The vtable entry is for a method defined directly in this class, and is never overridden
+      /// by subclasses.
+      NormalNonOverridden,
       /// The vtable entry is inherited from the superclass.
       Inherited,
       /// The vtable entry is inherited from the superclass, and overridden

lib/SIL/IR/SILPrinter.cpp

@@ -3127,6 +3127,9 @@ void SILVTable::print(llvm::raw_ostream &OS, bool Verbose) const {
     switch (entry.TheKind) {
     case SILVTable::Entry::Kind::Normal:
       break;
+    case SILVTable::Entry::Kind::NormalNonOverridden:
+      OS << " [nonoverridden]";
+      break;
     case SILVTable::Entry::Kind::Inherited:
       OS << " [inherited]";
       break;

lib/SIL/Parser/ParseSIL.cpp

@@ -6090,6 +6090,9 @@ bool SILParserState::parseSILVTable(Parser &P) {
         } else if (P.Tok.getText() == "inherited") {
           P.consumeToken();
           Kind = SILVTable::Entry::Kind::Inherited;
+        } else if (P.Tok.getText() == "nonoverridden") {
+          P.consumeToken();
+          Kind = SILVTable::Entry::Kind::NormalNonOverridden;
         } else {
           P.diagnose(P.Tok.getLoc(), diag::sil_vtable_bad_entry_kind);
           return true;

lib/Serialization/DeserializeSIL.cpp

@@ -79,6 +79,8 @@ static Optional<SILVTable::Entry::Kind>
 fromStableVTableEntryKind(unsigned value) {
   switch (value) {
   case SIL_VTABLE_ENTRY_NORMAL: return SILVTable::Entry::Kind::Normal;
+  case SIL_VTABLE_ENTRY_NORMAL_NON_OVERRIDDEN:
+    return SILVTable::Entry::Kind::NormalNonOverridden;
   case SIL_VTABLE_ENTRY_INHERITED: return SILVTable::Entry::Kind::Inherited;
   case SIL_VTABLE_ENTRY_OVERRIDE: return SILVTable::Entry::Kind::Override;
   default: return None;

lib/Serialization/ModuleFormat.h

@@ -55,7 +55,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 557; // COW instructions
+const uint16_t SWIFTMODULE_VERSION_MINOR = 558; // SILVTable entry kind for non-overridden entries
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///

lib/Serialization/SILFormat.h

@@ -51,6 +51,7 @@ using SILLinkageField = BCFixed<4>;
 
 enum SILVTableEntryKindEncoding : uint8_t {
   SIL_VTABLE_ENTRY_NORMAL,
+  SIL_VTABLE_ENTRY_NORMAL_NON_OVERRIDDEN,
   SIL_VTABLE_ENTRY_INHERITED,
   SIL_VTABLE_ENTRY_OVERRIDE,
 };

lib/Serialization/SerializeSIL.cpp

@@ -73,6 +73,8 @@ static unsigned toStableSILLinkage(SILLinkage linkage) {
 static unsigned toStableVTableEntryKind(SILVTable::Entry::Kind kind) {
   switch (kind) {
   case SILVTable::Entry::Kind::Normal: return SIL_VTABLE_ENTRY_NORMAL;
+  case SILVTable::Entry::Kind::NormalNonOverridden:
+    return SIL_VTABLE_ENTRY_NORMAL_NON_OVERRIDDEN;
   case SILVTable::Entry::Kind::Inherited: return SIL_VTABLE_ENTRY_INHERITED;
   case SILVTable::Entry::Kind::Override: return SIL_VTABLE_ENTRY_OVERRIDE;
   }