SIL: Avoid serializing the bodies of the original copies of @_backDeploy functions

include/swift/SIL/SILDeclRef.h

@@ -372,6 +372,8 @@ struct SILDeclRef {
   bool isNoinline() const;
   /// True if the function has __always inline attribute.
   bool isAlwaysInline() const;
+  /// True if the function has the @_backDeploy attribute.
+  bool isBackDeployed() const;
 
   /// Return the expected linkage of this declaration.
   SILLinkage getLinkage(ForDefinition_t forDefinition) const;

include/swift/SIL/SILLinkage.h

@@ -135,7 +135,7 @@ enum IsSerialized_t : unsigned char {
   ///
   /// This flag is only valid for Public, PublicNonABI, PublicExternal,
   /// HiddenExternal and Shared functions.
-  /// Functions with external linkage (PublicExternl, HiddenExternal) will not
+  /// Functions with external linkage (PublicExternal, HiddenExternal) will not
   /// be serialized, because they are available in a different module (from which
   /// they were de-serialized).
   ///

lib/SIL/IR/SILDeclRef.cpp

@@ -689,6 +689,19 @@ IsSerialized_t SILDeclRef::isSerialized() const {
   if (isClangImported())
     return IsSerialized;
 
+  // Handle back deployed functions. The original back deployed function
+  // should not be serialized, but the thunk and fallback should be since they
+  // need to be emitted into the client.
+  if (isBackDeployed()) {
+    switch (backDeploymentKind) {
+      case BackDeploymentKind::None:
+        return IsNotSerialized;
+      case BackDeploymentKind::Fallback:
+      case BackDeploymentKind::Thunk:
+        return IsSerialized;
+    }
+  }
+
   // Otherwise, ask the AST if we're inside an @inlinable context.
   if (dc->getResilienceExpansion() == ResilienceExpansion::Minimal)
     return IsSerialized;
@@ -736,6 +749,17 @@ bool SILDeclRef::isAlwaysInline() const {
   return false;
 }
 
+bool SILDeclRef::isBackDeployed() const {
+  if (!hasDecl())
+    return false;
+
+  auto *decl = getDecl();
+  if (auto afd = dyn_cast<AbstractFunctionDecl>(decl))
+    return afd->isBackDeployed();
+
+  return false;
+}
+
 bool SILDeclRef::isAnyThunk() const {
   return isForeignToNativeThunk() || isNativeToForeignThunk() ||
          isDistributedThunk() || isBackDeploymentThunk();

test/SILGen/back_deploy_attribute_accessor.swift

@@ -36,7 +36,7 @@ public struct TopLevelStruct {
   // CHECK:   return [[RETURN_BB_ARG]] : $TopLevelStruct
 
   // -- Original definition of TopLevelStruct.property.getter
-  // CHECK-LABEL: sil [serialized] [available 10.51] [ossa] @$s11back_deploy14TopLevelStructV8propertyACvg : $@convention(method) (TopLevelStruct) -> TopLevelStruct
+  // CHECK-LABEL: sil [available 10.51] [ossa] @$s11back_deploy14TopLevelStructV8propertyACvg : $@convention(method) (TopLevelStruct) -> TopLevelStruct
   @available(macOS 10.51, *)
   @_backDeploy(before: macOS 10.52)
   public var property: TopLevelStruct { self }

test/SILGen/back_deploy_attribute_func.swift

@@ -36,7 +36,7 @@
 // CHECK:   return [[RESULT]] : $()
 
 // -- Original definition of trivialFunc()
-// CHECK-LABEL: sil [serialized] [available 10.51] [ossa] @$s11back_deploy11trivialFuncyyF : $@convention(thin) () -> ()
+// CHECK-LABEL: sil [available 10.51] [ossa] @$s11back_deploy11trivialFuncyyF : $@convention(thin) () -> ()
 @available(macOS 10.51, *)
 @_backDeploy(before: macOS 10.52)
 public func trivialFunc() {}
@@ -71,7 +71,7 @@ public func trivialFunc() {}
 // CHECK:   return [[RETURN_BB_ARG]] : $Bool
 
 // -- Original definition of isNumber(_:)
-// CHECK-LABEL: sil [serialized] [available 10.51] [ossa] @$s11back_deploy8isNumberySbSiF : $@convention(thin) (Int) -> Bool
+// CHECK-LABEL: sil [available 10.51] [ossa] @$s11back_deploy8isNumberySbSiF : $@convention(thin) (Int) -> Bool
 @available(macOS 10.51, *)
 @_backDeploy(before: macOS 10.52)
 public func isNumber(_ x: Int) -> Bool {

test/SILGen/back_deploy_attribute_generic_func.swift

@@ -37,7 +37,7 @@
 // CHECK:   return [[RESULT]] : $()
 
 // -- Original definition of genericFunc()
-// CHECK-LABEL: sil [serialized] [available 10.51] [ossa] @$s11back_deploy11genericFuncyxxlF : $@convention(thin) <T> (@in_guaranteed T) -> @out T
+// CHECK-LABEL: sil [available 10.51] [ossa] @$s11back_deploy11genericFuncyxxlF : $@convention(thin) <T> (@in_guaranteed T) -> @out T
 @available(macOS 10.51, *)
 @_backDeploy(before: macOS 10.52)
 public func genericFunc<T>(_ t: T) -> T {

test/SILGen/back_deploy_attribute_struct_method.swift

@@ -38,7 +38,7 @@ public struct TopLevelStruct {
   // CHECK:   return [[RESULT]] : $()
 
   // -- Original definition of TopLevelStruct.trivialMethod()
-  // CHECK-LABEL: sil [serialized] [available 10.51] [ossa] @$s11back_deploy14TopLevelStructV13trivialMethodyyF : $@convention(method) (TopLevelStruct) -> ()
+  // CHECK-LABEL: sil [available 10.51] [ossa] @$s11back_deploy14TopLevelStructV13trivialMethodyyF : $@convention(method) (TopLevelStruct) -> ()
   @available(macOS 10.51, *)
   @_backDeploy(before: macOS 10.52)
   public func trivialMethod() {}

test/SILGen/back_deploy_attribute_throwing_func.swift

@@ -49,7 +49,7 @@
 // CHECK:   throw [[RETHROW_BB_ARG]] : $Error
 
 // -- Original definition of throwingFunc()
-// CHECK-LABEL: sil [serialized] [available 10.51] [ossa] @$s11back_deploy12throwingFuncyyKF : $@convention(thin) () -> @error Error
+// CHECK-LABEL: sil [available 10.51] [ossa] @$s11back_deploy12throwingFuncyyKF : $@convention(thin) () -> @error Error
 @available(macOS 10.51, *)
 @_backDeploy(before: macOS 10.52)
 public func throwingFunc() throws {}

test/attr/attr_backDeploy_evolution.swift

@@ -32,9 +32,6 @@
 // REQUIRES: executable_test
 // REQUIRES: VENDOR=apple
 
-// rdar://90525337
-// UNSUPPORTED: swift_test_mode_optimize
-
 // ---- (0) Prepare SDK
 // RUN: %empty-directory(%t)
 // RUN: %empty-directory(%t/SDK_ABI)
@@ -119,34 +116,34 @@ testPrint(handle: #dsohandle, "check")
 testPrint(handle: libraryHandle(), "check")
 
 if isV2OrLater() {
-  assert(!v2APIsAreStripped())
+  precondition(!v2APIsAreStripped())
 }
 
 // CHECK-ABI: library: trivial
 // CHECK-BD: client: trivial
 trivial()
 
-assert(try! pleaseThrow(false))
+precondition(try! pleaseThrow(false))
 do {
   _ = try pleaseThrow(true)
   fatalError("Should have thrown")
 } catch {
-  assert(error as? BadError == BadError.bad)
+  precondition(error as? BadError == BadError.bad)
 }
 
 do {
   let zero = MutableInt.zero
-  assert(zero.value == 0)
+  precondition(zero.value == 0)
 
   var int = MutableInt(5)
 
   // CHECK-ABI: library: 5
   // CHECK-BD: client: 5
   int.print()
 
-  assert(int.increment(by: 2) == 7)
-  assert(genericIncrement(&int, by: 3) == 10)
-  assert(int.decrement(by: 1) == 9)
+  precondition(int.increment(by: 2) == 7)
+  precondition(genericIncrement(&int, by: 3) == 10)
+  precondition(int.decrement(by: 1) == 9)
 
   var incrementable: any Incrementable = int.toIncrementable()
 
@@ -156,13 +153,13 @@ do {
 
   let int2 = MutableInt(0x7BB7914B)
   for (i, expectedByte) in [0x4B, 0x91, 0xB7, 0x7B].enumerated() {
-    assert(int2[byteAt: i] == expectedByte)
+    precondition(int2[byteAt: i] == expectedByte)
   }
 }
 
 do {
   let zero = ReferenceInt.zero
-  assert(zero.value == 0)
+  precondition(zero.value == 0)
 
   var int = ReferenceInt(42)
 
@@ -172,13 +169,13 @@ do {
 
   do {
     let copy = int.copy()
-    assert(int !== copy)
-    assert(copy.value == 42)
+    precondition(int !== copy)
+    precondition(copy.value == 42)
   }
 
-  assert(int.increment(by: 2) == 44)
-  assert(genericIncrement(&int, by: 3) == 47)
-  assert(int.decrement(by: 46) == 1)
+  precondition(int.increment(by: 2) == 44)
+  precondition(genericIncrement(&int, by: 3) == 47)
+  precondition(int.decrement(by: 46) == 1)
 
   var incrementable: any Incrementable = int.toIncrementable()
 
@@ -188,6 +185,6 @@ do {
 
   let int2 = MutableInt(0x08AFAB76)
   for (i, expectedByte) in [0x76, 0xAB, 0xAF, 0x08].enumerated() {
-    assert(int2[byteAt: i] == expectedByte)
+    precondition(int2[byteAt: i] == expectedByte)
   }
 }