SIL type lowering: Compute IsTypeExpansionSensitive and use it instead of TypeBase's hasOpaqueArchetypePropertiesOrCases

A type is IsTypeExpansionSensitive if it contains an opaque result type that influences how the type is lowered.

This could be because the type mentions an opaque archetype and
therefore we would look through to the underlying type depending on the
type expansion and could get a different SIL type. For example
'() -> out some P' could lower to '() -> @out Int'.

Or this could be because when we lower an aggregate type some of its
fields are opaque types that could be looked through and therefore the
aggregate has different lowering (e.g address vs. loadable) in different
type expansion contexts.

By replacing it this change also fixes an infinite recursion in
hasOpaqueArchetypePropertiesOrCases.

rdar://68798822

Author: aschwaighofer

include/swift/AST/Types.h

@@ -600,9 +600,6 @@ class alignas(1 << TypeAlignInBits) TypeBase {
   bool hasOpaqueArchetype() const {
     return getRecursiveProperties().hasOpaqueArchetype();
   }
-  /// Determine whether the type has any stored properties or enum cases that
-  /// involve an opaque type.
-  bool hasOpaqueArchetypePropertiesOrCases();
 
   /// Determine whether the type is an opened existential type.
   ///

include/swift/SIL/TypeLowering.h

@@ -147,16 +147,23 @@ enum IsResilient_t : bool {
   IsResilient = true
 };
 
+/// Does this type contain an opaque result type that affects type lowering?
+enum IsTypeExpansionSensitive_t : bool {
+  IsNotTypeExpansionSensitive = false,
+  IsTypeExpansionSensitive = true
+};
+
 /// Extended type information used by SIL.
 class TypeLowering {
 public:
   class RecursiveProperties {
     // These are chosen so that bitwise-or merges the flags properly.
     enum : unsigned {
-      NonTrivialFlag     = 1 << 0,
-      NonFixedABIFlag    = 1 << 1,
-      AddressOnlyFlag    = 1 << 2,
-      ResilientFlag      = 1 << 3,
+      NonTrivialFlag             = 1 << 0,
+      NonFixedABIFlag            = 1 << 1,
+      AddressOnlyFlag            = 1 << 2,
+      ResilientFlag              = 1 << 3,
+      TypeExpansionSensitiveFlag = 1 << 4,
     };
 
     uint8_t Flags;
@@ -165,15 +172,17 @@ class TypeLowering {
     /// a trivial, loadable, fixed-layout type.
     constexpr RecursiveProperties() : Flags(0) {}
 
-    constexpr RecursiveProperties(IsTrivial_t isTrivial,
-                                  IsFixedABI_t isFixedABI,
-                                  IsAddressOnly_t isAddressOnly,
-                                  IsResilient_t isResilient)
-      : Flags((isTrivial ? 0U : NonTrivialFlag) | 
-              (isFixedABI ? 0U : NonFixedABIFlag) |
-              (isAddressOnly ? AddressOnlyFlag : 0U) |
-              (isResilient ? ResilientFlag : 0U)) {}
-    
+    constexpr RecursiveProperties(
+        IsTrivial_t isTrivial, IsFixedABI_t isFixedABI,
+        IsAddressOnly_t isAddressOnly, IsResilient_t isResilient,
+        IsTypeExpansionSensitive_t isTypeExpansionSensitive =
+            IsNotTypeExpansionSensitive)
+        : Flags((isTrivial ? 0U : NonTrivialFlag) |
+                (isFixedABI ? 0U : NonFixedABIFlag) |
+                (isAddressOnly ? AddressOnlyFlag : 0U) |
+                (isResilient ? ResilientFlag : 0U) |
+                (isTypeExpansionSensitive ? TypeExpansionSensitiveFlag : 0U)) {}
+
     constexpr bool operator==(RecursiveProperties p) const {
       return Flags == p.Flags;
     }
@@ -183,7 +192,7 @@ class TypeLowering {
     }
 
     static constexpr RecursiveProperties forReference() {
-      return {IsNotTrivial, IsFixedABI, IsNotAddressOnly, IsNotResilient };
+      return {IsNotTrivial, IsFixedABI, IsNotAddressOnly, IsNotResilient};
     }
 
     static constexpr RecursiveProperties forOpaque() {
@@ -194,6 +203,7 @@ class TypeLowering {
       return {IsTrivial, IsFixedABI, IsNotAddressOnly, IsResilient};
     }
 
+
     void addSubobject(RecursiveProperties other) {
       Flags |= other.Flags;
     }
@@ -210,10 +220,19 @@ class TypeLowering {
     IsResilient_t isResilient() const {
       return IsResilient_t((Flags & ResilientFlag) != 0);
     }
+    IsTypeExpansionSensitive_t isTypeExpansionSensitive() const {
+      return IsTypeExpansionSensitive_t(
+          (Flags & TypeExpansionSensitiveFlag) != 0);
+    }
 
     void setNonTrivial() { Flags |= NonTrivialFlag; }
     void setNonFixedABI() { Flags |= NonFixedABIFlag; }
     void setAddressOnly() { Flags |= AddressOnlyFlag; }
+    void setTypeExpansionSensitive(
+        IsTypeExpansionSensitive_t isTypeExpansionSensitive) {
+      Flags = (Flags & ~TypeExpansionSensitiveFlag) |
+              (isTypeExpansionSensitive ? TypeExpansionSensitiveFlag : 0);
+    }
   };
 
 private:
@@ -305,6 +324,12 @@ class TypeLowering {
     return Properties.isResilient();
   }
 
+  /// Does this type contain an opaque result type that could influence how the
+  /// type is lowered if we could look through to the underlying type.
+  bool isTypeExpansionSensitive() const {
+    return Properties.isTypeExpansionSensitive();
+  }
+
   ResilienceExpansion getResilienceExpansion() const {
     return expansionContext.getResilienceExpansion();
   }
@@ -705,8 +730,6 @@ class TypeConverter {
 
   llvm::DenseMap<SILDeclRef, CaptureInfo> LoweredCaptures;
 
-  llvm::DenseMap<CanType, bool> opaqueArchetypeFields;
-
   /// Cache of loadable SILType to number of (estimated) fields
   ///
   /// Second element is a ResilienceExpansion.
@@ -719,17 +742,15 @@ class TypeConverter {
   Optional<CanType> BridgedType##Ty;
 #include "swift/SIL/BridgedTypes.def"
 
-  const TypeLowering &
-  getTypeLoweringForLoweredType(AbstractionPattern origType,
-                                CanType loweredType,
-                                TypeExpansionContext forExpansion,
-                                bool origHadOpaqueTypeArchetype);
+  const TypeLowering &getTypeLoweringForLoweredType(
+      AbstractionPattern origType, CanType loweredType,
+      TypeExpansionContext forExpansion,
+      IsTypeExpansionSensitive_t isTypeExpansionSensitive);
 
-  const TypeLowering *
-  getTypeLoweringForExpansion(TypeKey key,
-                              TypeExpansionContext forExpansion,
-                              const TypeLowering *lowering,
-                              bool origHadOpaqueTypeArchetype);
+  const TypeLowering *getTypeLoweringForExpansion(
+      TypeKey key, TypeExpansionContext forExpansion,
+      const TypeLowering *minimalExpansionLowering,
+      IsTypeExpansionSensitive_t isOrigTypeExpansionSensitive);
 
 public:
   ModuleDecl &M;
@@ -885,8 +906,6 @@ class TypeConverter {
 
   CanType getLoweredTypeOfGlobal(VarDecl *var);
 
-  bool hasOpaqueArchetypeOrPropertiesOrCases(CanType ty);
-
   /// Return the SILFunctionType for a native function value of the
   /// given type.
   CanSILFunctionType getSILFunctionType(TypeExpansionContext context,

lib/AST/Type.cpp

@@ -5048,27 +5048,6 @@ Type TypeBase::openAnyExistentialType(OpenedArchetypeType *&opened) {
   return opened;
 }
 
-bool TypeBase::hasOpaqueArchetypePropertiesOrCases() {
-  if (auto *structDecl = getStructOrBoundGenericStruct()) {
-    for (auto *field : structDecl->getStoredProperties()) {
-      auto fieldTy = field->getInterfaceType()->getCanonicalType();
-      if (fieldTy->hasOpaqueArchetype() ||
-          fieldTy->hasOpaqueArchetypePropertiesOrCases())
-        return true;
-    }
-  }
-
-  if (auto *enumDecl = getEnumOrBoundGenericEnum()) {
-    for (auto *elt : enumDecl->getAllElements()) {
-      auto eltType = elt->getInterfaceType();
-      if (eltType->hasOpaqueArchetype() ||
-          eltType->getCanonicalType()->hasOpaqueArchetypePropertiesOrCases())
-        return true;
-    }
-  }
-  return false;
-}
-
 CanType swift::substOpaqueTypesWithUnderlyingTypes(CanType ty,
                                                    TypeExpansionContext context,
                                                    bool allowLoweredTypes) {