Recurse Into Existential Types With Generic Structure

include/swift/AST/Types.h

@@ -5366,8 +5366,8 @@ class ParameterizedProtocolType final : public TypeBase,
 public:
   /// Retrieve an instance of a protocol composition type with the
   /// given set of members.
-  static Type get(const ASTContext &C, ProtocolType *base,
-                  ArrayRef<Type> args);
+  static ParameterizedProtocolType *get(const ASTContext &C, ProtocolType *base,
+                                        ArrayRef<Type> args);
 
   ProtocolType *getBaseType() const {
     return Base;
@@ -5407,6 +5407,13 @@ class ParameterizedProtocolType final : public TypeBase,
                             RecursiveTypeProperties properties);
 };
 BEGIN_CAN_TYPE_WRAPPER(ParameterizedProtocolType, Type)
+  static CanParameterizedProtocolType get(const ASTContext &C,
+                                          ProtocolType *base,
+                                          ArrayRef<Type> args) {
+    return CanParameterizedProtocolType(
+        ParameterizedProtocolType::get(C, base, args));
+  }
+
   CanProtocolType getBaseType() const {
     return CanProtocolType(getPointer()->getBaseType());
   }
@@ -5473,6 +5480,7 @@ class ExistentialType final : public TypeBase {
   }
 };
 BEGIN_CAN_TYPE_WRAPPER(ExistentialType, Type)
+  static CanExistentialType get(CanType constraint);
   PROXY_CAN_TYPE_SIMPLE_GETTER(getConstraintType)
 END_CAN_TYPE_WRAPPER(ExistentialType, Type)
 

include/swift/SIL/AbstractionPattern.h

@@ -1287,6 +1287,10 @@ class AbstractionPattern {
   /// it.
   AbstractionPattern getReferenceStorageReferentType() const;
 
+  /// Give that the value being abstracted is an existential, return the
+  /// underlying constraint type.
+  AbstractionPattern getExistentialConstraintType() const;
+
   /// Given that the value being abstracted is a function type, return the
   /// abstraction pattern for the derivative function.
   ///

lib/AST/ASTContext.cpp

@@ -3327,9 +3327,9 @@ ProtocolCompositionType::build(const ASTContext &C, ArrayRef<Type> Members,
   return compTy;
 }
 
-Type ParameterizedProtocolType::get(const ASTContext &C,
-                                    ProtocolType *baseTy,
-                                    ArrayRef<Type> args) {
+ParameterizedProtocolType *ParameterizedProtocolType::get(const ASTContext &C,
+                                                          ProtocolType *baseTy,
+                                                          ArrayRef<Type> args) {
   assert(args.size() > 0);
 
   bool isCanonical = baseTy->isCanonical();

lib/AST/Type.cpp

@@ -1641,7 +1641,7 @@ CanType TypeBase::computeCanonicalType() {
     for (Type t : PPT->getArgs())
       CanArgs.push_back(t->getCanonicalType());
     auto &C = Base->getASTContext();
-    Result = ParameterizedProtocolType::get(C, Base, CanArgs).getPointer();
+    Result = ParameterizedProtocolType::get(C, Base, CanArgs);
     break;
   }
   case TypeKind::Existential: {
@@ -3854,6 +3854,15 @@ operator()(CanType maybeOpaqueType, Type replacementType,
   return substRef;
 }
 
+CanExistentialType CanExistentialType::get(CanType constraint) {
+  assert(!(constraint->isAny() || constraint->isAnyObject()) &&
+         "Any(Object) may not apppear as canonical constraint type");
+  assert(!constraint->is<ExistentialMetatypeType>() &&
+         "Existential metatype may not apppear as canonical constraint type");
+  return CanExistentialType(
+      ExistentialType::get(constraint)->castTo<ExistentialType>());
+}
+
 CanPrimaryArchetypeType
 PrimaryArchetypeType::getNew(const ASTContext &Ctx,
                       GenericEnvironment *GenericEnv,

lib/SIL/IR/AbstractionPattern.cpp

@@ -943,6 +943,55 @@ AbstractionPattern AbstractionPattern::getReferenceStorageReferentType() const {
   llvm_unreachable("bad kind");
 }
 
+static CanType getExistentialConstraintType(CanType type) {
+  assert(type.isExistentialType());
+  if (auto *ET = type->getAs<ExistentialType>()) {
+    return CanType(ET->getConstraintType());
+  }
+  return type;
+}
+
+AbstractionPattern AbstractionPattern::getExistentialConstraintType() const {
+  switch (getKind()) {
+  case Kind::Invalid:
+    llvm_unreachable("querying invalid abstraction pattern!");
+  case Kind::ObjCMethodType:
+  case Kind::CurriedObjCMethodType:
+  case Kind::PartialCurriedObjCMethodType:
+  case Kind::CFunctionAsMethodType:
+  case Kind::CurriedCFunctionAsMethodType:
+  case Kind::PartialCurriedCFunctionAsMethodType:
+  case Kind::CXXMethodType:
+  case Kind::CurriedCXXMethodType:
+  case Kind::PartialCurriedCXXMethodType:
+  case Kind::Tuple:
+  case Kind::OpaqueFunction:
+  case Kind::OpaqueDerivativeFunction:
+  case Kind::ObjCCompletionHandlerArgumentsType:
+    llvm_unreachable("pattern for function or tuple cannot be for optional");
+
+  case Kind::Opaque:
+    return *this;
+
+  case Kind::Type:
+    if (isTypeParameterOrOpaqueArchetype())
+      return AbstractionPattern::getOpaque();
+    return AbstractionPattern(getGenericSignature(),
+                              ::getExistentialConstraintType(getType()));
+
+  case Kind::Discard:
+    return AbstractionPattern::getDiscard(
+        getGenericSignature(), ::getExistentialConstraintType(getType()));
+
+  case Kind::ClangType:
+    // This is not reflected in clang types.
+    return AbstractionPattern(getGenericSignature(),
+                              ::getExistentialConstraintType(getType()),
+                              getClangType());
+  }
+  llvm_unreachable("bad kind");
+}
+
 void AbstractionPattern::dump() const {
   print(llvm::errs());
   llvm::errs() << "\n";
@@ -1683,6 +1732,44 @@ class SubstFunctionTypePatternVisitor
     llvm_unreachable("Unimplemented!");
   }
 
+  CanType visitExistentialType(ExistentialType *exist,
+                               AbstractionPattern pattern) {
+    if (auto gp = handleTypeParameterInAbstractionPattern(pattern, exist))
+      return gp;
+
+    // Avoid walking into the constraint type if we can help it.
+    if (!exist->hasTypeParameter() && !exist->hasArchetype() &&
+        !exist->hasOpaqueArchetype()) {
+      return CanType(exist);
+    }
+
+    return CanExistentialType::get(visit(
+        exist->getConstraintType(), pattern.getExistentialConstraintType()));
+  }
+
+  CanType visitParameterizedProtocolType(ParameterizedProtocolType *ppt,
+                                         AbstractionPattern pattern) {
+    if (auto gp = handleTypeParameterInAbstractionPattern(pattern, ppt))
+      return gp;
+
+    // Recurse into the arguments of the parameterized protocol.
+    SmallVector<Type, 4> substArgs;
+    auto origPPT = pattern.getAs<ParameterizedProtocolType>();
+    if (!origPPT)
+      return CanType(ppt);
+
+    for (unsigned i = 0; i < ppt->getArgs().size(); ++i) {
+      auto argTy = ppt->getArgs()[i];
+      auto origArgTy = AbstractionPattern(pattern.getGenericSignatureOrNull(),
+                                          origPPT.getArgs()[i]);
+      auto substEltTy = visit(argTy, origArgTy);
+      substArgs.push_back(substEltTy);
+    }
+
+    return CanType(ParameterizedProtocolType::get(
+        TC.Context, ppt->getBaseType(), substArgs));
+  }
+
   CanType visitTupleType(TupleType *tuple, AbstractionPattern pattern) {
     if (auto gp = handleTypeParameterInAbstractionPattern(pattern, tuple))
       return gp;

lib/SIL/IR/TypeLowering.cpp

@@ -2500,6 +2500,47 @@ TypeConverter::computeLoweredRValueType(TypeExpansionContext forExpansion,
                                              MetatypeRepresentation::Thick);
     }
 
+    CanType visitExistentialType(CanExistentialType substExistType) {
+      // Try to avoid walking into the constraint type if we can help it
+      if (!substExistType->hasTypeParameter() &&
+          !substExistType->hasArchetype() &&
+          !substExistType->hasOpaqueArchetype()) {
+        return substExistType;
+      }
+
+      return CanExistentialType::get(visit(substExistType.getConstraintType()));
+    }
+
+    CanType
+    visitParameterizedProtocolType(CanParameterizedProtocolType substPPT) {
+      bool changed = false;
+      SmallVector<Type, 4> loweredSubstArgs;
+      loweredSubstArgs.reserve(substPPT.getArgs().size());
+
+      auto origConstraint = origType.getExistentialConstraintType();
+      auto origPPT = origConstraint.getAs<ParameterizedProtocolType>();
+      if (!origPPT)
+        return substPPT;
+
+      for (auto i : indices(substPPT.getArgs())) {
+        auto origArgTy = AbstractionPattern(
+            origConstraint.getGenericSignatureOrNull(), origPPT.getArgs()[i]);
+        auto substArgType = substPPT.getArgs()[i];
+
+        CanType loweredSubstEltType =
+            TC.getLoweredRValueType(forExpansion, origArgTy, substArgType);
+        changed = changed || substArgType != loweredSubstEltType;
+
+        loweredSubstArgs.push_back(loweredSubstEltType);
+      }
+
+      if (!changed)
+        return substPPT;
+
+      return CanParameterizedProtocolType::get(
+          TC.Context, substPPT->getBaseType(), loweredSubstArgs);
+    }
+
     CanType visitPackType(CanPackType substPackType) {
       llvm_unreachable("");
     }

test/SILGen/parameterized_existentials.swift

@@ -22,6 +22,11 @@ struct S: Q {
   typealias Z = Float
 }
 
+struct R<T, U, V> {
+  var force: () -> any P<T, U, V>
+  // CHECK-LABEL: sil hidden [ossa] @$s13parameterized1RV5forceACyxq_q0_GAA1P_pyxq_q0_XPyc_tcfC : $@convention(method) <T, U, V> (@owned @callee_guaranteed @substituted <τ_0_0, τ_0_1, τ_0_2> () -> @out P<τ_0_0, τ_0_1, τ_0_2> for <T, U, V>, @thin R<T, U, V>.Type) -> @owned R<T, U, V> {
+}
+
 // CHECK-LABEL: sil hidden [ossa] @$s13parameterized6upcastyAA1P_pAA1SVF : $@convention(thin) (S) -> @out P {
 func upcast(_ x: S) -> any P {
   // CHECK: bb0([[RESULT_PARAM:%.*]] : $*P, [[CONCRETE_VAL:%.*]] : $S):
@@ -88,3 +93,8 @@ func upcastResult() {
 
   reuse({ () -> any Q<Int, String, Float> in S() })
 }
+
+// CHECK-LABEL: sil hidden [ossa] @$s13parameterized5forceAA1P_pyxq_q0_XPyr1_lF : $@convention(thin) <T, U, V> () -> @out P<T, U, V> {
+func force<T, U, V>() -> any P<T, U, V> {
+  return R(force: { force() }).force()
+}