Merge pull request swiftlang#24560 from DougGregor/opaque-generic-sig-arena

[AST] Allocate GenericSignature(Builders) in the arena

Author: DougGregor

include/swift/AST/GenericSignature.h

@@ -312,6 +312,12 @@ class alignas(1 << TypeAlignInBits) GenericSignature final
   /// generic parameters to themselves.
   SubstitutionMap getIdentitySubstitutionMap() const;
 
+  /// Whether this generic signature involves a type variable.
+  bool hasTypeVariable() const;
+
+  /// Whether the given set of requirements involves a type variable.
+  static bool hasTypeVariable(ArrayRef<Requirement> requirements);
+
   static void Profile(llvm::FoldingSetNodeID &ID,
                       TypeArrayView<GenericTypeParamType> genericParams,
                       ArrayRef<Requirement> requirements);

lib/AST/ASTContext.cpp

@@ -245,16 +245,6 @@ FOR_KNOWN_FOUNDATION_TYPES(CACHE_FOUNDATION_DECL)
   /// Stores information about lazy deserialization of various declarations.
   llvm::DenseMap<const DeclContext *, LazyContextData *> LazyContexts;
 
-  /// Stored generic signature builders for canonical generic signatures.
-  llvm::DenseMap<GenericSignature *, std::unique_ptr<GenericSignatureBuilder>>
-    GenericSignatureBuilders;
-
-  /// Canonical generic environments for canonical generic signatures.
-  ///
-  /// The keys are the generic signature builders in \c GenericSignatureBuilders.
-  llvm::DenseMap<GenericSignatureBuilder *, GenericEnvironment *>
-    CanonicalGenericEnvironments;
-  
   /// The single-parameter generic signature with no constraints, <T>.
   CanGenericSignature SingleGenericParameterSignature;
 
@@ -327,6 +317,19 @@ FOR_KNOWN_FOUNDATION_TYPES(CACHE_FOUNDATION_DECL)
     llvm::FoldingSet<LayoutConstraintInfo> LayoutConstraints;
     llvm::FoldingSet<OpaqueTypeArchetypeType> OpaqueArchetypes;
 
+    llvm::FoldingSet<GenericSignature> GenericSignatures;
+
+    /// Stored generic signature builders for canonical generic signatures.
+    llvm::DenseMap<GenericSignature *, std::unique_ptr<GenericSignatureBuilder>>
+      GenericSignatureBuilders;
+
+    /// Canonical generic environments for canonical generic signatures.
+    ///
+    /// The keys are the generic signature builders in
+    /// \c GenericSignatureBuilders.
+    llvm::DenseMap<GenericSignatureBuilder *, GenericEnvironment *>
+      CanonicalGenericEnvironments;
+
     /// The set of function types.
     llvm::FoldingSet<FunctionType> FunctionTypes;
 
@@ -377,7 +380,6 @@ FOR_KNOWN_FOUNDATION_TYPES(CACHE_FOUNDATION_DECL)
   llvm::FoldingSet<SILBoxType> SILBoxTypes;
   llvm::DenseMap<BuiltinIntegerWidth, BuiltinIntegerType*> IntegerTypes;
   llvm::FoldingSet<BuiltinVectorType> BuiltinVectorTypes;
-  llvm::FoldingSet<GenericSignature> GenericSignatures;
   llvm::FoldingSet<DeclName::CompoundDeclName> CompoundNames;
   llvm::DenseMap<UUID, OpenedArchetypeType *> OpenedExistentialArchetypes;
 
@@ -1427,34 +1429,50 @@ void ASTContext::getVisibleTopLevelClangModules(
     collectAllModules(Modules);
 }
 
+static AllocationArena getArena(GenericSignature *genericSig) {
+  if (!genericSig)
+    return AllocationArena::Permanent;
+
+  if (genericSig->hasTypeVariable())
+    return AllocationArena::ConstraintSolver;
+
+  return AllocationArena::Permanent;
+}
+
 void ASTContext::registerGenericSignatureBuilder(
                                        GenericSignature *sig,
                                        GenericSignatureBuilder &&builder) {
   auto canSig = sig->getCanonicalSignature();
-  auto known = getImpl().GenericSignatureBuilders.find(canSig);
-  if (known != getImpl().GenericSignatureBuilders.end()) {
+  auto arena = getArena(sig);
+  auto &genericSignatureBuilders =
+      getImpl().getArena(arena).GenericSignatureBuilders;
+  auto known = genericSignatureBuilders.find(canSig);
+  if (known != genericSignatureBuilders.end()) {
     ++NumRegisteredGenericSignatureBuildersAlready;
     return;
   }
 
   ++NumRegisteredGenericSignatureBuilders;
-  getImpl().GenericSignatureBuilders[canSig] =
+  genericSignatureBuilders[canSig] =
     llvm::make_unique<GenericSignatureBuilder>(std::move(builder));
 }
 
 GenericSignatureBuilder *ASTContext::getOrCreateGenericSignatureBuilder(
                                                       CanGenericSignature sig) {
   // Check whether we already have a generic signature builder for this
   // signature and module.
-  auto known = getImpl().GenericSignatureBuilders.find(sig);
-  if (known != getImpl().GenericSignatureBuilders.end())
+  auto arena = getArena(sig);
+  auto &genericSignatureBuilders =
+      getImpl().getArena(arena).GenericSignatureBuilders;
+  auto known = genericSignatureBuilders.find(sig);
+  if (known != genericSignatureBuilders.end())
     return known->second.get();
 
   // Create a new generic signature builder with the given signature.
   auto builder = new GenericSignatureBuilder(*this);
 
   // Store this generic signature builder (no generic environment yet).
-  getImpl().GenericSignatureBuilders[sig] =
+  genericSignatureBuilders[sig] =
     std::unique_ptr<GenericSignatureBuilder>(builder);
 
   builder->addGenericSignature(sig);
@@ -1525,12 +1543,16 @@ GenericSignatureBuilder *ASTContext::getOrCreateGenericSignatureBuilder(
 GenericEnvironment *ASTContext::getOrCreateCanonicalGenericEnvironment(
                                               GenericSignatureBuilder *builder,
                                               GenericSignature *sig) {
-  auto known = getImpl().CanonicalGenericEnvironments.find(builder);
-  if (known != getImpl().CanonicalGenericEnvironments.end())
+  auto arena = getArena(sig);
+  auto &canonicalGenericEnvironments =
+      getImpl().getArena(arena).CanonicalGenericEnvironments;
+
+  auto known = canonicalGenericEnvironments.find(builder);
+  if (known != canonicalGenericEnvironments.end())
     return known->second;
 
   auto env = sig->createGenericEnvironment();
-  getImpl().CanonicalGenericEnvironments[builder] = env;
+  canonicalGenericEnvironments[builder] = env;
   return env;
 }
 
@@ -3774,10 +3796,14 @@ GenericSignature::get(TypeArrayView<GenericTypeParamType> params,
   llvm::FoldingSetNodeID ID;
   GenericSignature::Profile(ID, params, requirements);
 
+  auto arena = GenericSignature::hasTypeVariable(requirements)
+      ? AllocationArena::ConstraintSolver
+      : AllocationArena::Permanent;
+
   auto &ctx = getASTContext(params, requirements);
   void *insertPos;
-  if (auto *sig = ctx.getImpl().GenericSignatures.FindNodeOrInsertPos(ID,
-                                                                 insertPos)) {
+  if (auto *sig = ctx.getImpl().getArena(arena).GenericSignatures
+          .FindNodeOrInsertPos(ID, insertPos)) {
     if (isKnownCanonical)
       sig->CanonicalSignatureOrASTContext = &ctx;
 
@@ -3790,7 +3816,7 @@ GenericSignature::get(TypeArrayView<GenericTypeParamType> params,
   void *mem = ctx.Allocate(bytes, alignof(GenericSignature));
   auto newSig = new (mem) GenericSignature(params, requirements,
                                            isKnownCanonical);
-  ctx.getImpl().GenericSignatures.InsertNode(newSig, insertPos);
+  ctx.getImpl().getArena(arena).GenericSignatures.InsertNode(newSig, insertPos);
   return newSig;
 }
 

lib/AST/GenericSignature.cpp

@@ -1042,3 +1042,28 @@ unsigned GenericSignature::getGenericParamOrdinal(GenericTypeParamType *param) {
     .findIndexIn(getGenericParams());
 }
 
+bool GenericSignature::hasTypeVariable() const {
+  return hasTypeVariable(getRequirements());
+}
+
+bool GenericSignature::hasTypeVariable(ArrayRef<Requirement> requirements) {
+  for (const auto &req : requirements) {
+    if (req.getFirstType()->hasTypeVariable())
+      return true;
+
+    switch (req.getKind()) {
+    case RequirementKind::Layout:
+      break;
+
+    case RequirementKind::Conformance:
+    case RequirementKind::SameType:
+    case RequirementKind::Superclass:
+      if (req.getSecondType()->hasTypeVariable())
+        return true;
+      break;
+    }
+  }
+
+  return false;
+}
+

lib/AST/GenericSignatureBuilder.cpp

@@ -5404,9 +5404,15 @@ namespace {
                             ArrayRef<Constraint<T>> constraints,
                             llvm::function_ref<bool(const Constraint<T> &)>
                                                    isSuitableRepresentative) {
+    Optional<Constraint<T>> fallbackConstraint;
+
     // Find a representative constraint.
     Optional<Constraint<T>> representativeConstraint;
     for (const auto &constraint : constraints) {
+      // Make sure we have a constraint to fall back on.
+      if (!fallbackConstraint)
+        fallbackConstraint = constraint;
+
       // If this isn't a suitable representative constraint, ignore it.
       if (!isSuitableRepresentative(constraint))
         continue;
@@ -5457,7 +5463,8 @@ namespace {
         representativeConstraint = constraint;
     }
 
-    return representativeConstraint;
+    return representativeConstraint ? representativeConstraint
+                                    : fallbackConstraint;
   }
 } // end anonymous namespace
 
@@ -6996,9 +7003,11 @@ void GenericSignatureBuilder::checkConcreteTypeConstraints(
       if (concreteType->isEqual(equivClass->concreteType))
         return ConstraintRelation::Redundant;
 
-      // If either has a type parameter, call them unrelated.
+      // If either has a type parameter or type variable, call them unrelated.
       if (concreteType->hasTypeParameter() ||
-          equivClass->concreteType->hasTypeParameter())
+          equivClass->concreteType->hasTypeParameter() ||
+          concreteType->hasTypeVariable() ||
+          equivClass->concreteType->hasTypeVariable())
         return ConstraintRelation::Unrelated;
 
       return ConstraintRelation::Conflicting;

validation-test/compiler_crashers_2_fixed/0194-rdar50309503.swift

@@ -0,0 +1,14 @@
+// RUN: %target-swift-frontend -emit-ir -o /dev/null %s
+
+protocol P {
+  associatedtype AT
+  func foo() -> AT
+}
+
+struct X<C1: Collection, C2: Collection, T>: P
+    where C1.Element == C2.Element
+{
+  func foo() -> some P {
+    return self
+  }
+}