Merge pull request swiftlang#23323 from davezarzycki/shrink_ast_densemaps

Shrink AST DenseMaps

Author: davezarzycki

include/swift/AST/Types.h

@@ -2332,7 +2332,9 @@ enum class MetatypeRepresentation : char {
   /// which permit dynamic behavior.
   Thick,
   /// An Objective-C metatype refers to an Objective-C class object.
-  ObjC
+  ObjC,
+
+  Last_MetatypeRepresentation = ObjC
 };
 
 /// AnyMetatypeType - A common parent class of MetatypeType and

lib/AST/ASTContext.cpp

@@ -301,15 +301,22 @@ FOR_KNOWN_FOUNDATION_TYPES(CACHE_FOUNDATION_DECL)
   /// Structure that captures data that is segregated into different
   /// arenas.
   struct Arena {
+    static_assert(alignof(TypeBase) >= 8, "TypeBase not 8-byte aligned?");
+    static_assert(alignof(TypeBase) > static_cast<unsigned>(
+               MetatypeRepresentation::Last_MetatypeRepresentation) + 1,
+               "Use std::pair for MetatypeTypes and ExistentialMetatypeTypes.");
+
     llvm::DenseMap<Type, ErrorType *> ErrorTypesWithOriginal;
     llvm::FoldingSet<TypeAliasType> TypeAliasTypes;
     llvm::FoldingSet<TupleType> TupleTypes;
-    llvm::DenseMap<std::pair<Type,char>, MetatypeType*> MetatypeTypes;
-    llvm::DenseMap<std::pair<Type,char>,
+    llvm::DenseMap<llvm::PointerIntPair<TypeBase*, 3, unsigned>,
+                   MetatypeType*> MetatypeTypes;
+    llvm::DenseMap<llvm::PointerIntPair<TypeBase*, 3, unsigned>,
                    ExistentialMetatypeType*> ExistentialMetatypeTypes;
     llvm::DenseMap<Type, ArraySliceType*> ArraySliceTypes;
     llvm::DenseMap<std::pair<Type, Type>, DictionaryType *> DictionaryTypes;
     llvm::DenseMap<Type, OptionalType*> OptionalTypes;
+    llvm::DenseMap<Type, ParenType*> SimpleParenTypes; // Most are simple
     llvm::DenseMap<std::pair<Type, unsigned>, ParenType*> ParenTypes;
     llvm::DenseMap<uintptr_t, ReferenceStorageType*> ReferenceStorageTypes;
     llvm::DenseMap<Type, LValueType*> LValueTypes;
@@ -2088,6 +2095,7 @@ size_t ASTContext::Implementation::Arena::getTotalMemory() const {
     llvm::capacity_in_bytes(ArraySliceTypes) +
     llvm::capacity_in_bytes(DictionaryTypes) +
     llvm::capacity_in_bytes(OptionalTypes) +
+    llvm::capacity_in_bytes(SimpleParenTypes) +
     llvm::capacity_in_bytes(ParenTypes) +
     llvm::capacity_in_bytes(ReferenceStorageTypes) +
     llvm::capacity_in_bytes(LValueTypes) +
@@ -3045,8 +3053,10 @@ ParenType *ParenType::get(const ASTContext &C, Type underlying,
 
   auto properties = underlying->getRecursiveProperties();
   auto arena = getArena(properties);
-  ParenType *&Result =
-      C.getImpl().getArena(arena).ParenTypes[{underlying, fl.toRaw()}];
+  auto flags = fl.toRaw();
+  ParenType *&Result = flags == 0
+      ? C.getImpl().getArena(arena).SimpleParenTypes[underlying]
+      : C.getImpl().getArena(arena).ParenTypes[{underlying, flags}];
   if (Result == nullptr) {
     Result = new (C, arena) ParenType(underlying,
                                       properties, fl);
@@ -3492,13 +3502,16 @@ MetatypeType *MetatypeType::get(Type T, Optional<MetatypeRepresentation> Repr,
   auto properties = T->getRecursiveProperties();
   auto arena = getArena(properties);
 
-  char reprKey;
+  unsigned reprKey;
   if (Repr.hasValue())
-    reprKey = static_cast<char>(*Repr) + 1;
+    reprKey = static_cast<unsigned>(*Repr) + 1;
   else
     reprKey = 0;
 
-  MetatypeType *&Entry = Ctx.getImpl().getArena(arena).MetatypeTypes[{T, reprKey}];
+  auto pair = llvm::PointerIntPair<TypeBase*, 3, unsigned>(T.getPointer(),
+                                                           reprKey);
+
+  MetatypeType *&Entry = Ctx.getImpl().getArena(arena).MetatypeTypes[pair];
   if (Entry) return Entry;
 
   return Entry = new (Ctx, arena) MetatypeType(
@@ -3517,13 +3530,16 @@ ExistentialMetatypeType::get(Type T, Optional<MetatypeRepresentation> repr,
   auto properties = T->getRecursiveProperties();
   auto arena = getArena(properties);
 
-  char reprKey;
+  unsigned reprKey;
   if (repr.hasValue())
-    reprKey = static_cast<char>(*repr) + 1;
+    reprKey = static_cast<unsigned>(*repr) + 1;
   else
     reprKey = 0;
 
-  auto &entry = ctx.getImpl().getArena(arena).ExistentialMetatypeTypes[{T, reprKey}];
+  auto pair = llvm::PointerIntPair<TypeBase*, 3, unsigned>(T.getPointer(),
+                                                           reprKey);
+
+  auto &entry = ctx.getImpl().getArena(arena).ExistentialMetatypeTypes[pair];
   if (entry) return entry;
 
   return entry = new (ctx, arena) ExistentialMetatypeType(