Bridging: Implement several optional- and enum-related bridges (#85756)

In #85757, part of the changes resolving #68944 is submitted. Most
bridges required for #85757 were previously implemented in #84648. After
#82653 got merged, we have demand for several new bridges in order to
properly support optimizing derivatives of throwing functions via
AutoDiff Closure Specialization pass.

This patch implements:

- **AST:**

   * `var optionalObjectType: Type` property of `Type` struct
   
   * `var optionalType: Type` property of `Type` struct

- **SIL:**

  * `let name: StringRef` property of `EnumCase` struct

* `func createOptionalSome(operand: Value, type: Type) -> EnumInst`
method of `Builder`

* `func createOptionalNone(type: Type) -> EnumInst` method of `Builder`

SwiftCompilerSources/Sources/AST/Type.swift

@@ -63,6 +63,15 @@ public struct Type: TypeProperties, CustomStringConvertible, NoReflectionChildre
 
   public var builtinVectorElementType: Type { Type(bridged: bridged.getBuiltinVectorElementType()) }
 
+  public var optionalObjectType: Type {
+    assert(self.isOptional)
+    return genericArgumentsOfBoundGenericType[0]
+  }
+
+  public var optionalType: Type {
+    return Type(bridged: bridged.getOptionalType())
+  }
+
   public func subst(with substitutionMap: SubstitutionMap) -> Type {
     return Type(bridged: bridged.subst(substitutionMap.bridged))
   }
@@ -92,6 +101,10 @@ public struct Type: TypeProperties, CustomStringConvertible, NoReflectionChildre
   public var kindOfGenericTypeParameter: GenericTypeParameterKind {
     bridged.GenericTypeParam_getParamKind()
   }
+
+  public var genericArgumentsOfBoundGenericType: TypeArray {
+    TypeArray(bridged: bridged.BoundGenericType_getGenericArgs())
+  }
 }
 
 /// A Type that is statically known to be canonical.

SwiftCompilerSources/Sources/SIL/Builder.swift

@@ -573,6 +573,17 @@ public struct Builder {
     return notifyNew(enumInst.getAs(EnumInst.self))
   }
 
+  static let optionalNoneCaseIndex = 0
+  static let optionalSomeCaseIndex = 1
+
+  public func createOptionalNone(type: Type) -> EnumInst {
+    return createEnum(caseIndex: Self.optionalNoneCaseIndex, payload: nil, enumType: type)
+  }
+
+  public func createOptionalSome(operand: Value, type: Type) -> EnumInst {
+    return createEnum(caseIndex: Self.optionalSomeCaseIndex, payload: operand, enumType: type)
+  }
+
   public func createThinToThickFunction(thinFunction: Value, resultType: Type) -> ThinToThickFunctionInst {
     let tttf = bridged.createThinToThickFunction(thinFunction.bridged, resultType.bridged)
     return notifyNew(tttf.getAs(ThinToThickFunctionInst.self))

SwiftCompilerSources/Sources/SIL/Type.swift

@@ -291,6 +291,7 @@ public struct EnumCase {
   public let enumElementDecl : EnumElementDecl
   public let payload: Type?
   public let index: Int
+  public var name: StringRef { enumElementDecl.name }
 }
 
 public struct EnumCases : CollectionLikeSequence, IteratorProtocol {
@@ -329,7 +330,7 @@ public struct EnumCases : CollectionLikeSequence, IteratorProtocol {
     if currentIndex == index && !enumType.bridged.isEndCaseIterator(iterator) {
       return EnumCase(enumElementDecl: enumType.bridged.getEnumElementDecl(iterator).getAs(EnumElementDecl.self),
                       payload: enumType.bridged.getEnumCasePayload(iterator, function.bridged).typeOrNil,
-                      index: caseIndex)
+                      index: index)
     }
     return nil
   }

include/swift/AST/ASTBridging.h

@@ -83,6 +83,7 @@ enum class RequirementReprKind : unsigned;
 }
 
 struct BridgedASTType;
+struct BridgedASTTypeArray;
 class BridgedCanType;
 class BridgedASTContext;
 class BridgedLangOptions;
@@ -3046,6 +3047,7 @@ struct BridgedASTType {
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedASTType getBuiltinVectorElementType() const;
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedCanType getBuiltinFixedArrayElementType() const;
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedCanType getBuiltinFixedArraySizeType() const;
+  SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedASTType getOptionalType() const;
   BRIDGED_INLINE bool isBuiltinFixedWidthInteger(SwiftInt width) const;
   BRIDGED_INLINE bool isOptional() const;
   BRIDGED_INLINE bool isBuiltinType() const;
@@ -3079,6 +3081,8 @@ struct BridgedASTType {
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedConformance checkConformance(BridgedDeclObj proto) const;
   BRIDGED_INLINE bool containsSILPackExpansionType() const;
   BRIDGED_INLINE bool isSILPackElementAddress() const;
+  SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedASTTypeArray
+  BoundGenericType_getGenericArgs() const;
 };
 
 class BridgedCanType {

include/swift/AST/ASTBridgingImpl.h

@@ -639,6 +639,10 @@ BridgedCanType BridgedASTType::getBuiltinFixedArraySizeType() const {
   return unbridged()->castTo<swift::BuiltinFixedArrayType>()->getSize();
 }
 
+BridgedASTType BridgedASTType::getOptionalType() const {
+  return {swift::OptionalType::get(unbridged())};
+}
+
 bool BridgedASTType::isBuiltinFixedWidthInteger(SwiftInt width) const {
   if (auto *intTy = unbridged()->getAs<swift::BuiltinIntegerType>())
     return intTy->isFixedWidth((unsigned)width);
@@ -782,6 +786,10 @@ BridgedASTType::GenericTypeParam_getParamKind() const {
   return llvm::cast<swift::GenericTypeParamType>(type)->getParamKind();
 }
 
+BridgedASTTypeArray BridgedASTType::BoundGenericType_getGenericArgs() const {
+  return {llvm::cast<swift::BoundGenericType>(type)->getGenericArgs()};
+}
+
 static_assert((int)BridgedASTType::TraitResult::IsNot == (int)swift::TypeTraitResult::IsNot);
 static_assert((int)BridgedASTType::TraitResult::CanBe == (int)swift::TypeTraitResult::CanBe);
 static_assert((int)BridgedASTType::TraitResult::Is == (int)swift::TypeTraitResult::Is);