Sema: Optimize Constraint layout to save 24 bytes

include/swift/Sema/Constraint.h

@@ -336,6 +336,8 @@ class Constraint final : public llvm::ilist_node<Constraint>,
     private llvm::TrailingObjects<Constraint,
                                   TypeVariableType *,
                                   ConstraintFix *,
+                                  DeclContext *,
+                                  ContextualTypeInfo,
                                   OverloadChoice> {
   friend TrailingObjects;
 
@@ -345,9 +347,17 @@ class Constraint final : public llvm::ilist_node<Constraint>,
   /// The kind of restriction placed on this constraint.
   ConversionRestrictionKind Restriction : 8;
 
-  /// Whether we have a fix.
+  /// The number of type variables referenced by this constraint.
+  ///
+  /// The type variables themselves are tail-allocated.
+  unsigned NumTypeVariables : 11;
+
+  /// Whether we have a tail-allocated fix.
   unsigned HasFix : 1;
 
+  /// Whether we have a tail-allocated DeclContext.
+  unsigned HasDeclContext : 1;
+
   /// Whether the \c Restriction field is valid.
   unsigned HasRestriction : 1;
 
@@ -375,14 +385,19 @@ class Constraint final : public llvm::ilist_node<Constraint>,
   /// the rest of the constraint system. Currently only applies to conjunctions.
   unsigned IsIsolated : 1;
 
-  /// The number of type variables referenced by this constraint.
-  ///
-  /// The type variables themselves are tail-allocated.
-  unsigned NumTypeVariables : 11;
-
   /// The kind of function reference, for member references.
   unsigned TheFunctionRefInfo : 3;
 
+  /// The trailing closure matching for an applicable function constraint,
+  /// if any. 0 = None, 1 = Forward, 2 = Backward.
+  unsigned trailingClosureMatching : 2;
+
+  /// For a SyntacticElement constraint, identify whether the result of this
+  /// node is unused.
+  unsigned isDiscarded : 1;
+
+  // 22 bits remaining
+
   union {
     struct {
       /// The first type.
@@ -414,29 +429,19 @@ class Constraint final : public llvm::ilist_node<Constraint>,
         /// Used for ValueWitness constraints.
         ValueDecl *Ref;
       } Member;
-
-      /// The DC in which the use appears.
-      DeclContext *UseDC;
     } Member;
 
     /// The set of constraints for a disjunction.
     ArrayRef<Constraint *> Nested;
 
     struct {
-      /// The first type
+      /// The first type.
       Type First;
-
-      /// The DC in which the use appears.
-      DeclContext *UseDC;
     } Overload;
 
     struct {
       /// The node itself.
       ASTNode Element;
-      /// Contextual information associated with the element (if any).
-      ContextualTypeInfo Context;
-      /// Identifies whether result of this node is unused.
-      bool IsDiscarded;
     } SyntacticElement;
 
     struct {
@@ -447,11 +452,6 @@ class Constraint final : public llvm::ilist_node<Constraint>,
       /// The type being called, primarily a function type, but could
       /// be a metatype, a tuple or a nominal type.
       Type Callee;
-      /// The trailing closure matching for an applicable function constraint,
-      /// if any. 0 = None, 1 = Forward, 2 = Backward.
-      unsigned TrailingClosureMatching : 2;
-      /// The declaration context in which the application appears.
-      DeclContext *UseDC;
     } Apply;
   };
 
@@ -527,6 +527,14 @@ class Constraint final : public llvm::ilist_node<Constraint>,
     return HasFix ? 1 : 0;
   }
 
+  size_t numTrailingObjects(OverloadToken<DeclContext *>) const {
+    return HasDeclContext ? 1 : 0;
+  }
+
+  size_t numTrailingObjects(OverloadToken<ContextualTypeInfo>) const {
+    return Kind == ConstraintKind::SyntacticElement ? 1 : 0;
+  }
+
   size_t numTrailingObjects(OverloadToken<OverloadChoice>) const {
     return Kind == ConstraintKind::BindOverload ? 1 : 0;
   }
@@ -604,15 +612,15 @@ class Constraint final : public llvm::ilist_node<Constraint>,
       DeclContext *useDC, ConstraintLocator *locator);
 
   static Constraint *createSyntacticElement(ConstraintSystem &cs,
-                                              ASTNode node,
-                                              ConstraintLocator *locator,
-                                              bool isDiscarded = false);
+                                            ASTNode node,
+                                            ConstraintLocator *locator,
+                                            bool isDiscarded = false);
 
   static Constraint *createSyntacticElement(ConstraintSystem &cs,
-                                              ASTNode node,
-                                              ContextualTypeInfo context,
-                                              ConstraintLocator *locator,
-                                              bool isDiscarded = false);
+                                            ASTNode node,
+                                            ContextualTypeInfo context,
+                                            ConstraintLocator *locator,
+                                            bool isDiscarded = false);
 
   /// Determine the kind of constraint.
   ConstraintKind getKind() const { return Kind; }
@@ -864,24 +872,10 @@ class Constraint final : public llvm::ilist_node<Constraint>,
 
   /// Retrieve the overload choice for an overload-binding constraint.
   OverloadChoice getOverloadChoice() const {
-    assert(Kind == ConstraintKind::BindOverload);
+    ASSERT(Kind == ConstraintKind::BindOverload);
     return *getTrailingObjects<OverloadChoice>();
   }
 
-  /// Retrieve the DC in which the overload was used.
-  DeclContext *getOverloadUseDC() const {
-    assert(Kind == ConstraintKind::BindOverload);
-    return Overload.UseDC;
-  }
-
-  /// Retrieve the DC in which the member was used.
-  DeclContext *getMemberUseDC() const {
-    assert(Kind == ConstraintKind::ValueMember ||
-           Kind == ConstraintKind::UnresolvedValueMember ||
-           Kind == ConstraintKind::ValueWitness);
-    return Member.UseDC;
-  }
-
   FunctionType *getAppliedFunctionType() const {
     assert(Kind == ConstraintKind::ApplicableFunction);
     return Apply.AppliedFn;
@@ -892,24 +886,25 @@ class Constraint final : public llvm::ilist_node<Constraint>,
     return Apply.Callee;
   }
 
-  DeclContext *getApplicationDC() const {
-    assert(Kind == ConstraintKind::ApplicableFunction);
-    return Apply.UseDC;
-  }
-
   ASTNode getSyntacticElement() const {
     assert(Kind == ConstraintKind::SyntacticElement);
     return SyntacticElement.Element;
   }
 
   ContextualTypeInfo getElementContext() const {
-    assert(Kind == ConstraintKind::SyntacticElement);
-    return SyntacticElement.Context;
+    ASSERT(Kind == ConstraintKind::SyntacticElement);
+    return *getTrailingObjects<ContextualTypeInfo>();
   }
 
   bool isDiscardedElement() const {
     assert(Kind == ConstraintKind::SyntacticElement);
-    return SyntacticElement.IsDiscarded;
+    return isDiscarded;
+  }
+
+  /// Retrieve the DC in which the overload was used.
+  DeclContext *getDeclContext() const {
+    ASSERT(HasDeclContext);
+    return *getTrailingObjects<DeclContext *>();
   }
 
   /// For an applicable function constraint, retrieve the trailing closure

include/swift/Sema/ConstraintSolverStats.def

@@ -18,6 +18,7 @@
 #  error #define CS_STATISTIC(Name, Description) before including
 #endif
 
+CS_STATISTIC(ASTBytesAllocated, "bytes allocated in solver arena")
 CS_STATISTIC(NumTypeVariablesBound, "# of type variables bound")
 CS_STATISTIC(NumTypeVariableBindings, "# of type variable bindings attempted")
 CS_STATISTIC(NumDisjunctions, "# of disjunctions explored")

lib/AST/ASTContext.cpp

@@ -575,12 +575,6 @@ struct ASTContext::Implementation {
     /// The set of function types.
     llvm::FoldingSet<FunctionType> FunctionTypes;
 
-    /// The set of normal protocol conformances.
-    llvm::FoldingSet<NormalProtocolConformance> NormalConformances;
-
-    // The set of self protocol conformances.
-    llvm::DenseMap<ProtocolDecl*, SelfProtocolConformance*> SelfConformances;
-
     /// The set of specialized protocol conformances.
     llvm::FoldingSet<SpecializedProtocolConformance> SpecializedConformances;
 
@@ -597,9 +591,6 @@ struct ASTContext::Implementation {
     /// The set of substitution maps (uniqued by their storage).
     llvm::FoldingSet<SubstitutionMap::Storage> SubstitutionMaps;
 
-    /// The set of unique AvailabilityContexts (uniqued by their storage).
-    llvm::FoldingSet<AvailabilityContext::Storage> AvailabilityContexts;
-
     ~Arena() {
       for (auto &conformance : SpecializedConformances)
         conformance.~SpecializedProtocolConformance();
@@ -613,11 +604,6 @@ struct ASTContext::Implementation {
 #if SWIFT_COMPILER_IS_MSVC
 #pragma warning (default: 4189)
 #endif
-
-      // Call the normal conformance destructors last since they could be
-      // referenced by the other conformance types.
-      for (auto &conformance : NormalConformances)
-        conformance.~NormalProtocolConformance();
     }
 
     size_t getTotalMemory() const;
@@ -645,6 +631,11 @@ struct ASTContext::Implementation {
       AutoDiffDerivativeFunctionIdentifiers;
 
   llvm::FoldingSet<GenericSignatureImpl> GenericSignatures;
+  llvm::FoldingSet<NormalProtocolConformance> NormalConformances;
+  llvm::DenseMap<ProtocolDecl*, SelfProtocolConformance*> SelfConformances;
+
+  /// The set of unique AvailabilityContexts (uniqued by their storage).
+  llvm::FoldingSet<AvailabilityContext::Storage> AvailabilityContexts;
 
   /// A cache of information about whether particular nominal types
   /// are representable in a foreign language.
@@ -720,6 +711,9 @@ ASTContext::Implementation::Implementation()
     : IdentifierTable(Allocator),
       IntrinsicScratchContext(new llvm::LLVMContext()) {}
 ASTContext::Implementation::~Implementation() {
+  for (auto &conformance : NormalConformances)
+    conformance.~NormalProtocolConformance();
+
   for (auto &cleanup : Cleanups)
     cleanup();
 }
@@ -889,6 +883,9 @@ void ASTContext::Implementation::dump(llvm::raw_ostream &os) const {
   SIZE_AND_BYTES(SILMoveOnlyWrappedTypes);
   SIZE_AND_BYTES(BuiltinIntegerTypes);
   SIZE_AND_BYTES(OpenedElementEnvironments);
+  SIZE(NormalConformances);
+  SIZE(SelfConformances);
+  SIZE(AvailabilityContexts);
   SIZE_AND_BYTES(ForeignRepresentableCache);
   SIZE(SearchPathsSet);
 
@@ -2912,15 +2909,14 @@ ASTContext::getNormalConformance(Type conformingType,
 
   // Did we already record the normal conformance?
   void *insertPos;
-  auto &normalConformances =
-    getImpl().getArena(AllocationArena::Permanent).NormalConformances;
+  auto &normalConformances = getImpl().NormalConformances;
   if (auto result = normalConformances.FindNodeOrInsertPos(id, insertPos))
     return result;
 
   // Build a new normal protocol conformance.
-  auto result = new (*this, AllocationArena::Permanent)
-      NormalProtocolConformance(conformingType, protocol, loc, dc, state,
-                                options, preconcurrencyLoc);
+  auto result = new (*this) NormalProtocolConformance(
+      conformingType, protocol, loc, dc, state,
+      options, preconcurrencyLoc);
   normalConformances.InsertNode(result, insertPos);
 
   return result;
@@ -2929,12 +2925,11 @@ ASTContext::getNormalConformance(Type conformingType,
 /// Produce a self-conformance for the given protocol.
 SelfProtocolConformance *
 ASTContext::getSelfConformance(ProtocolDecl *protocol) {
-  auto &selfConformances =
-    getImpl().getArena(AllocationArena::Permanent).SelfConformances;
+  auto &selfConformances = getImpl().SelfConformances;
   auto &entry = selfConformances[protocol];
   if (!entry) {
-    entry = new (*this, AllocationArena::Permanent)
-      SelfProtocolConformance(protocol->getDeclaredExistentialType());
+    entry = new (*this) SelfProtocolConformance(
+      protocol->getDeclaredExistentialType());
   }
   return entry;
 }
@@ -3274,6 +3269,9 @@ size_t ASTContext::getTotalMemory() const {
     // getImpl().GenericSignatures ?
     // getImpl().CompoundNames ?
     // getImpl().IntegerTypes ?
+    // getImpl().NormalConformances ?
+    // getImpl().SelfConformances ?
+    // getImpl().AvailabilityContexts
     getImpl().Permanent.getTotalMemory();
 
     Size += getSolverMemory();
@@ -3315,7 +3313,6 @@ size_t ASTContext::Implementation::Arena::getTotalMemory() const {
     // FunctionTypes ?
     // UnboundGenericTypes ?
     // BoundGenericTypes ?
-    // NormalConformances ?
     // SpecializedConformances ?
     // InheritedConformances ?
     // BuiltinConformances ?
@@ -3360,14 +3357,11 @@ void ASTContext::Implementation::Arena::dump(llvm::raw_ostream &os) const {
     SIZE_AND_BYTES(OpaqueArchetypeEnvironments);
     SIZE_AND_BYTES(OpenedExistentialEnvironments);
     SIZE(FunctionTypes);
-    SIZE(NormalConformances);
-    SIZE(SelfConformances);
     SIZE(SpecializedConformances);
     SIZE(InheritedConformances);
     SIZE_AND_BYTES(BuiltinConformances);
     SIZE(PackConformances);
     SIZE(SubstitutionMaps);
-    SIZE(AvailabilityContexts);
 
 #undef SIZE
 #undef SIZE_AND_BYTES
@@ -5720,8 +5714,7 @@ const AvailabilityContext::Storage *AvailabilityContext::Storage::get(
   AvailabilityContext::Storage::Profile(id, platformRange, isDeprecated,
                                         domainInfos);
 
-  auto &foldingSet =
-      ctx.getImpl().getArena(AllocationArena::Permanent).AvailabilityContexts;
+  auto &foldingSet = ctx.getImpl().AvailabilityContexts;
   void *insertPos;
   auto *existing = foldingSet.FindNodeOrInsertPos(id, insertPos);
   if (existing)

lib/Sema/CSSimplify.cpp

@@ -13089,7 +13089,7 @@ bool ConstraintSystem::simplifyAppliedOverloadsImpl(
         // Determine the type that this choice will have.
         Type choiceType = getEffectiveOverloadType(
             constraint->getLocator(), choice, /*allowMembers=*/true,
-            constraint->getOverloadUseDC());
+            constraint->getDeclContext());
         if (!choiceType) {
           hasUnhandledConstraints = true;
           return true;
@@ -16335,7 +16335,7 @@ ConstraintSystem::simplifyConstraint(const Constraint &constraint) {
     return simplifyApplicableFnConstraint(
         constraint.getAppliedFunctionType(), constraint.getCalleeType(),
         constraint.getTrailingClosureMatching(),
-        constraint.getApplicationDC(), /*flags=*/std::nullopt,
+        constraint.getDeclContext(), /*flags=*/std::nullopt,
         constraint.getLocator());
 
   case ConstraintKind::DynamicCallableApplicableFunction:
@@ -16382,7 +16382,7 @@ ConstraintSystem::simplifyConstraint(const Constraint &constraint) {
 
     resolveOverload(constraint.getLocator(), constraint.getFirstType(),
                     constraint.getOverloadChoice(),
-                    constraint.getOverloadUseDC());
+                    constraint.getDeclContext());
     return SolutionKind::Solved;
 
   case ConstraintKind::SubclassOf:
@@ -16429,7 +16429,7 @@ ConstraintSystem::simplifyConstraint(const Constraint &constraint) {
   case ConstraintKind::UnresolvedValueMember:
     return simplifyMemberConstraint(
         constraint.getKind(), constraint.getFirstType(), constraint.getMember(),
-        constraint.getSecondType(), constraint.getMemberUseDC(),
+        constraint.getSecondType(), constraint.getDeclContext(),
         constraint.getFunctionRefInfo(),
         /*outerAlternatives=*/{},
         /*flags*/ std::nullopt, constraint.getLocator());
@@ -16438,7 +16438,7 @@ ConstraintSystem::simplifyConstraint(const Constraint &constraint) {
     return simplifyValueWitnessConstraint(
         constraint.getKind(), constraint.getFirstType(),
         constraint.getRequirement(), constraint.getSecondType(),
-        constraint.getMemberUseDC(), constraint.getFunctionRefInfo(),
+        constraint.getDeclContext(), constraint.getFunctionRefInfo(),
         /*flags*/ std::nullopt, constraint.getLocator());
 
   case ConstraintKind::Defaultable: