Bridging: Implement bridges required for ongoing AutoDiff changes #84648

kovdan01 · 2025-10-02T14:47:05Z

In #83926, part of the changes resolving #68944 is submitted. The AutoDiff closure specialization optimizer pass relies on several AST-level bridges not implemented yet.

This patch introduces these missing bridges. See the list of the changes below.

AST:

Define .asValueDecl on each BridgedXXXDecl type that's also a ValueDecl.
Define .asNominalTypeDecl on each BridgedXXXDecl type that's also a NominalTypeDecl.
Define .asGenericContext on each BridgedXXXDecl type that's also a GenericContext.
class BridgedSourceFile:
- Make nullable
- func addTopLevelDecl(_ decl: BridgedDecl)
class BridgedFileUnit:
- func castToSourceFile() -> BridgedNullableSourceFile
class BridgedDecl:
- func getDeclContext() -> BridgedDeclContext
class BridgedParamDecl:
- func cloneWithoutType() -> BridgedParamDecl
- func setInterfaceType(_ type : BridgedASTType)
Define BridgedDecl.setImplicit() instead of BridgedParamDecl.setImplicit()
class BridgedGenericContext:
- setGenericSignature(_ genSig: BridgedGenericSignature)
Change return type of BridgedEnumDecl.createParsed(/*...*/) from BridgedNominalTypeDecl to BridgedEnumDecl
class BridgedValueDecl:
- func setAccess(_ accessLevel: swift.AccessLevel)
class BridgedNominalTypeDecl:
- func addMember(_ member: BridgedDecl)
class BridgedGenericTypeParamDecl:
- func createImplicit(declContext: BridgedDeclContext, name: swift.Identifier, depth: UInt, index: UInt, paramKind: swift.GenericTypeParamKind)
class ValueDecl:
- var baseIdentifier: swift.Identifier
class NominalTypeDecl:
- var declaredInterfaceType: Type
class EnumElementDecl:
- var parameterList: BridgedParameterList
- var nameStr: StringRef
struct GenericSignature:
- var canonicalSignature: CanGenericSignature
struct CanGenericSignature:
- var isEmpty: Bool
- var genericSignature: GenericSignature
struct Type:
- func mapTypeOutOfContext() -> Type
- func getReducedType(sig: GenericSignature) -> CanonicalType
- func GenericTypeParam_getName() -> swift.Identifier
- func GenericTypeParam_getDepth() -> UInt
- func GenericTypeParam_getIndex() -> UInt
- func GenericTypeParam_getParamKind() -> swift.GenericTypeParamKind
struct CanonicalType:
- func SILFunctionType_getSubstGenericSignature() -> CanGenericSignature
- func loweredType(in function: SIL.Function) -> SIL.Type

SIL:

class Argument:
- func replaceAllUsesWith(newArg: Argument)
class BasicBlock:
- func insertPhiArgument(atPosition: Int, type: Type, ownership: Ownership, _ context: some MutatingContext) -> Argument
struct Builder:
- func createTuple(elements: [Value]) -> TupleInst
protocol Context:
- func getTupleType(elements: [AST.Type]) -> AST.Type
- func getTupleTypeWithLabels(elements: [AST.Type], labels: [swift.Identifier]) -> AST.Type
class Function:
- var sourceFile: BridgedNullableSourceFile
- func mapTypeIntoContext(_ type: Type) -> Type
class PartialApplyInst:
- var substitutionMap: SubstitutionMap
class SwitchEnumInst:
- var numCases: Int
- public func getSuccessorForDefault() -> BasicBlock?
Type:
- var category: ValueCategory
- func getEnumCasePayload(caseIdx: Int, function: Function) -> Type
- func mapTypeOutOfContext() -> Type
- static func getPrimitiveType(canType: CanonicalType, silValueCategory: ValueCategory) -> Type
struct EnumCase:
- let enumElementDecl: EnumElementDecl
struct TupleElementArray:
- func label(at index: Int) -> swift.Identifier
Define enum ValueCategory with address and object elements

kovdan01 · 2025-10-02T14:49:54Z

Tagging @JaapWijnen

asl · 2025-10-02T15:30:57Z

@kovdan01 Will you please summarize the list of changes in the PR description? Overall, while these are prerequisites for autodiff-related closure specialization pass, overall these bridges are not autodiff-specific.

In #83926, part of the changes resolving #68944 is submitted. The AutoDiff closure specialization optimizer pass relies on several bridges not implemented yet. This patch introduces these missing bridges. See the list of the changes below. **AST:** * Define `.asValueDecl` on each BridgedXXXDecl type that's also a ValueDecl. * Define `.asNominalTypeDecl` on each BridgedXXXDecl type that's also a NominalTypeDecl. * Define `.asGenericContext` on each BridgedXXXDecl type that's also a GenericContext. * `class BridgedSourceFile`: - Make nullable - `func addTopLevelDecl(_ decl: BridgedDecl)` * `class BridgedFileUnit`: - `func castToSourceFile() -> BridgedNullableSourceFile` * `class BridgedDecl`: - `func getDeclContext() -> BridgedDeclContext` * `class BridgedParamDecl`: - `func cloneWithoutType() -> BridgedParamDecl` - `func setInterfaceType(_ type : BridgedASTType)` * Define `BridgedDecl.setImplicit()` instead of `BridgedParamDecl.setImplicit()` * `class BridgedGenericContext`: - `setGenericSignature(_ genSig: BridgedGenericSignature)` * Change return type of `BridgedEnumDecl.createParsed(/*...*/)` from `BridgedNominalTypeDecl` to `BridgedEnumDecl` * `class BridgedValueDecl`: - `func setAccess(_ accessLevel: swift.AccessLevel)` * `class BridgedNominalTypeDecl`: - `func addMember(_ member: BridgedDecl)` * `class BridgedGenericTypeParamDecl`: - `func createImplicit(declContext: BridgedDeclContext, name: swift.Identifier, depth: UInt, index: UInt, paramKind: swift.GenericTypeParamKind)` * `class ValueDecl`: - `var baseIdentifier: swift.Identifier` * `class NominalTypeDecl`: - `var declaredInterfaceType: Type` * `class EnumElementDecl`: - `var parameterList: BridgedParameterList` - `var nameStr: StringRef` * `struct GenericSignature`: - `var canonicalSignature: CanGenericSignature` * `struct CanGenericSignature`: - `var isEmpty: Bool` - `var genericSignature: GenericSignature` * `struct Type`: - `func mapTypeOutOfContext() -> Type` - `func getReducedType(sig: GenericSignature) -> CanonicalType` - `func GenericTypeParam_getName() -> swift.Identifier` - `func GenericTypeParam_getDepth() -> UInt` - `func GenericTypeParam_getIndex() -> UInt` - `func GenericTypeParam_getParamKind() -> swift.GenericTypeParamKind` * `struct CanonicalType`: - `func SILFunctionType_getSubstGenericSignature() -> CanGenericSignature` - `func loweredType(in function: SIL.Function) -> SIL.Type` **SIL:** * `class Argument`: - `func replaceAllUsesWith(newArg: Argument)` * `class BasicBlock`: - `func insertPhiArgument(atPosition: Int, type: Type, ownership: Ownership, _ context: some MutatingContext) -> Argument` * `struct Builder`: - `func createTuple(elements: [Value]) -> TupleInst` * `protocol Context`: - `func getTupleType(elements: [AST.Type]) -> AST.Type` - `func getTupleTypeWithLabels(elements: [AST.Type], labels: [swift.Identifier]) -> AST.Type` * `class Function`: - `var sourceFile: BridgedNullableSourceFile` - `func mapTypeIntoContext(_ type: Type) -> Type` * `class PartialApplyInst`: - `var substitutionMap: SubstitutionMap` * `class SwitchEnumInst`: - `var numCases: Int` - `public func getSuccessorForDefault() -> BasicBlock?` * `Type`: - `var category: ValueCategory` - `func getEnumCasePayload(caseIdx: Int, function: Function) -> Type` - `func mapTypeOutOfContext() -> Type` - `static func getPrimitiveType(canType: CanonicalType, silValueCategory: ValueCategory) -> Type` * `struct EnumCase`: - `let enumElementDecl: EnumElementDecl` * `struct TupleElementArray`: - `func label(at index: Int) -> swift.Identifier` * Define `enum ValueCategory` with `address` and `object` elements

kovdan01 · 2025-10-06T14:58:59Z

@kovdan01 Will you please summarize the list of changes in the PR description? Overall, while these are prerequisites for autodiff-related closure specialization pass, overall these bridges are not autodiff-specific.

@asl Thanks for suggestion, updated the comment

kovdan01 · 2025-10-06T15:09:59Z

@swift-ci please test

eeckstein · 2025-10-06T16:22:58Z

@kovdan01 I'll review this tomorrow

eeckstein · 2025-10-07T08:15:29Z

SwiftCompilerSources/Sources/AST/Declarations.swift

 public class ValueDecl: Decl {
  final public var nameLoc: SourceLoc? { SourceLoc(bridged: bridged.Value_getNameLoc()) }
  final public var userFacingName: StringRef { StringRef(bridged: bridged.Value_getUserFacingName()) }
+  final public var baseIdentifier: swift.Identifier { bridged.Value_getBaseIdentifier() }


Please don't expose the swift namespace in APIs. Instead add a type alias:

typealias Identifier = swift.Identifier

eeckstein · 2025-10-07T08:16:09Z

SwiftCompilerSources/Sources/AST/Declarations.swift

    bridged.NominalType_getValueTypeDestructor().getAs(DestructorDecl.self)
  }
+
+  public var declaredInterfaceType : AST.`Type` {


No need to qualify Type in the AST module. Just use Type

eeckstein · 2025-10-07T08:19:52Z

SwiftCompilerSources/Sources/AST/Declarations.swift


 final public class EnumElementDecl: ValueDecl {
  public var hasAssociatedValues: Bool { bridged.EnumElementDecl_hasAssociatedValues() }
+  public var parameterList: BridgedParameterList { bridged.EnumElementDecl_getParameterList() }


Please don't expose bridged data structures in APIs. Create a native swift ParameterList containing a var bridged: BridgedParameterList

eeckstein · 2025-10-07T08:20:40Z

SwiftCompilerSources/Sources/AST/Declarations.swift

 final public class EnumElementDecl: ValueDecl {
  public var hasAssociatedValues: Bool { bridged.EnumElementDecl_hasAssociatedValues() }
+  public var parameterList: BridgedParameterList { bridged.EnumElementDecl_getParameterList() }
+  public var nameStr: StringRef { StringRef(bridged: bridged.EnumElementDecl_getNameStr()) }


Just call it name

eeckstein · 2025-10-07T08:25:21Z

SwiftCompilerSources/Sources/AST/GenericSignature.swift

+  public var canonicalSignature: CanGenericSignature { CanGenericSignature(bridged: bridged.getCanonicalSignature()) }
+}
+
+public struct CanGenericSignature {


Please avoid abbreviations. Better: CanonicalGenericSignature

We should follow the general swift API design guidelines. You can take a look at https://www.swift.org/documentation/api-design-guidelines/

eeckstein · 2025-10-07T09:28:06Z

lib/AST/Bridging/DeclBridging.cpp

 #define ABSTRACT_DECL(Id, Parent) DECL(Id, Parent)
 #include "swift/AST/DeclNodes.def"

+// Define `.asValueDecl` on each BridgedXXXDecl type that's also a


What is this for? Doing this kind of unchecked cast (for all kind of decls) looks dangerous.

This is only handling VALUE_DECL so it should be safe. Otherwise, the compiler should complain at static_cast. Same for .asNominalTypeDecl.

Apparently .asValueDecl is not used, but assuming this is going to be used in subsequent PRs for #68944, I think it's fine to have it.

eeckstein · 2025-10-07T09:28:15Z

lib/AST/Bridging/DeclBridging.cpp

+  }
+#include "swift/AST/DeclNodes.def"
+
+// Define `.asNominalTypeDecl` on each BridgedXXXDecl type that's also a


eeckstein · 2025-10-07T09:30:35Z

lib/AST/Bridging/DeclBridging.cpp

  });
 }

+BridgedDeclContext BridgedDecl_getDeclContext(BridgedDecl decl) {


do you need this?

eeckstein · 2025-10-07T09:30:55Z

lib/AST/Bridging/DeclBridging.cpp

+  return decl.unbridged()->getDeclContext();
+}
+
+void BridgedValueDecl_setAccess(BridgedValueDecl decl,


eeckstein · 2025-10-07T09:32:12Z

lib/AST/Bridging/GenericsBridging.cpp

  return decl;
 }

+BridgedGenericTypeParamDecl BridgedGenericTypeParamDecl_createImplicit(


rintaro · 2025-10-08T18:58:07Z

include/swift/AST/ASTBridging.h

 void BridgedDecl_forEachDeclToHoist(BridgedDecl decl,
                                    BridgedSwiftClosure closure);

+SWIFT_NAME("BridgedDecl.getDeclContext(self:)")


Suggested change

SWIFT_NAME("BridgedDecl.getDeclContext(self:)")

SWIFT_NAME("getter:BridgedDecl.declContext(self:)")

kovdan01 requested a review from asl October 2, 2025 14:49

kovdan01 force-pushed the users/kovdan01/ast-bridges-for-autodiff-closure-spec branch from 10085d6 to b3d31c7 Compare October 6, 2025 14:58

kovdan01 added the bridging Feature → casting: type bridging label Oct 6, 2025

kovdan01 marked this pull request as ready for review October 6, 2025 15:09

kovdan01 requested review from CodaFi, bnbarham, eeckstein, hamishknight, hborla, jckarter, rintaro, slavapestov and xedin as code owners October 6, 2025 15:09

eeckstein marked this pull request as draft October 6, 2025 16:23

eeckstein requested changes Oct 7, 2025

View reviewed changes

rintaro reviewed Oct 8, 2025

View reviewed changes

	SWIFT_NAME("BridgedDecl.getDeclContext(self:)")
	SWIFT_NAME("getter:BridgedDecl.declContext(self:)")

Bridging: Implement bridges required for ongoing AutoDiff changes #84648

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Bridging: Implement bridges required for ongoing AutoDiff changes #84648

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asl commented Oct 2, 2025

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kovdan01 commented Oct 2, 2025 •

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