swift SIL: add Function thunk APIs

* `var thunkKind`
* `set(thunkKind:)`

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/PassManager/Context.swift

@@ -610,6 +610,16 @@ extension Function {
     bridged.setNeedStackProtection(needStackProtection)
   }
 
+  func set(thunkKind: ThunkKind, _ context: FunctionPassContext) {
+    context.notifyEffectsChanged()
+    switch thunkKind {
+    case .noThunk:                 bridged.setThunk(.IsNotThunk)
+    case .thunk:                   bridged.setThunk(.IsThunk)
+    case .reabstractionThunk:      bridged.setThunk(.IsReabstractionThunk)
+    case .signatureOptimizedThunk: bridged.setThunk(.IsSignatureOptimizedThunk)
+    }
+  }
+
   func fixStackNesting(_ context: FunctionPassContext) {
     context._bridged.fixStackNesting(bridged)
   }

SwiftCompilerSources/Sources/SIL/Function.swift

@@ -261,6 +261,21 @@ final public class Function : CustomStringConvertible, HasShortDescription, Hash
   public var isSerialized: Bool { bridged.isSerialized() }
   public var hasValidLinkageForFragileRef: Bool { bridged.hasValidLinkageForFragileRef() }
 
+  public enum ThunkKind {
+    case noThunk, thunk, reabstractionThunk, signatureOptimizedThunk
+  }
+
+  var thunkKind: ThunkKind {
+    switch bridged.isThunk() {
+    case .IsNotThunk:                return .noThunk
+    case .IsThunk:                   return .thunk
+    case .IsReabstractionThunk:      return .reabstractionThunk
+    case .IsSignatureOptimizedThunk: return .signatureOptimizedThunk
+    default:
+      fatalError()
+    }
+  }
+
   /// True, if the function runs with a swift 5.1 runtime.
   /// Note that this is function specific, because inlinable functions are de-serialized
   /// in a client module, which might be compiled with a different deployment target.

include/swift/SIL/SILBridging.h

@@ -499,6 +499,13 @@ struct BridgedFunction {
     AlwaysInline
   };
 
+  enum class ThunkKind {
+    IsNotThunk,
+    IsThunk,
+    IsReabstractionThunk,
+    IsSignatureOptimizedThunk
+  };
+
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE swift::SILFunction * _Nonnull getFunction() const;
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedStringRef getName() const;
   SWIFT_IMPORT_UNSAFE BridgedOwnedString getDebugDescription() const;
@@ -531,6 +538,8 @@ struct BridgedFunction {
   BRIDGED_INLINE InlineStrategy getInlineStrategy() const;
   BRIDGED_INLINE bool isSerialized() const;
   BRIDGED_INLINE bool hasValidLinkageForFragileRef() const;
+  BRIDGED_INLINE ThunkKind isThunk() const;
+  BRIDGED_INLINE void setThunk(ThunkKind) const;
   BRIDGED_INLINE bool needsStackProtection() const;
   BRIDGED_INLINE void setNeedStackProtection(bool needSP) const;
   BRIDGED_INLINE bool isResilientNominalDecl(BridgedNominalTypeDecl decl) const;

include/swift/SIL/SILBridgingImpl.h

@@ -648,6 +648,14 @@ BridgedFunction::InlineStrategy BridgedFunction::getInlineStrategy() const {
   return (InlineStrategy)getFunction()->getInlineStrategy();
 }
 
+BridgedFunction::ThunkKind BridgedFunction::isThunk() const {
+  return (ThunkKind)getFunction()->isThunk();
+}
+
+void BridgedFunction::setThunk(ThunkKind kind) const {
+  getFunction()->setThunk((swift::IsThunk_t)kind);
+}
+
 bool BridgedFunction::isSerialized() const {
   return getFunction()->isSerialized();
 }

lib/SIL/Utils/SILBridging.cpp

@@ -221,6 +221,11 @@ static_assert((int)BridgedFunction::InlineStrategy::InlineDefault == (int)swift:
 static_assert((int)BridgedFunction::InlineStrategy::NoInline == (int)swift::NoInline);
 static_assert((int)BridgedFunction::InlineStrategy::AlwaysInline == (int)swift::AlwaysInline);
 
+static_assert((int)BridgedFunction::ThunkKind::IsNotThunk == (int)swift::IsNotThunk);
+static_assert((int)BridgedFunction::ThunkKind::IsThunk == (int)swift::IsThunk);
+static_assert((int)BridgedFunction::ThunkKind::IsReabstractionThunk == (int)swift::IsReabstractionThunk);
+static_assert((int)BridgedFunction::ThunkKind::IsSignatureOptimizedThunk == (int)swift::IsSignatureOptimizedThunk);
+
 BridgedOwnedString BridgedFunction::getDebugDescription() const {
   std::string str;
   llvm::raw_string_ostream os(str);