Devirtualization: make sure to de-serialize the body of shared deinit functions.

Sometimes it can happen that a deinit function, which is imported from another module, has shared linkage.
In this case it is important to de-serialize the function body. Otherwise it would be illegal SIL.

rdar://140112207

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/PassManager/Context.swift

@@ -227,6 +227,14 @@ extension MutatingContext {
     }
   }
 
+  func loadFunction(function: Function, loadCalleesRecursively: Bool) -> Bool {
+    if function.isDefinition {
+      return true
+    }
+    _bridged.loadFunction(function.bridged, loadCalleesRecursively)
+    return function.isDefinition
+  }
+
   private func notifyNewInstructions(from: Instruction, to: Instruction) {
     var inst = from
     while inst != to {
@@ -305,14 +313,6 @@ struct FunctionPassContext : MutatingContext {
     }
   }
 
-  func loadFunction(function: Function, loadCalleesRecursively: Bool) -> Bool {
-    if function.isDefinition {
-      return true
-    }
-    _bridged.loadFunction(function.bridged, loadCalleesRecursively)
-    return function.isDefinition
-  }
-
   /// Looks up a function in the `Swift` module.
   /// The `name` is the source name of the function and not the mangled name.
   /// Returns nil if no such function or multiple matching functions are found.

SwiftCompilerSources/Sources/Optimizer/Utilities/Devirtualization.swift

@@ -43,6 +43,10 @@ private func devirtualize(destroy: some DevirtualizableDestroy, _ context: some
     guard let deinitFunc = context.lookupDeinit(ofNominal: nominal) else {
       return false
     }
+    if deinitFunc.linkage == .shared && !deinitFunc.isDefinition {
+      // Make sure to not have an external shared function, which is illegal in SIL.
+      _ = context.loadFunction(function: deinitFunc, loadCalleesRecursively: false)
+    }
     destroy.createDeinitCall(to: deinitFunc, context)
     context.erase(instruction: destroy)
     return true

test/SILOptimizer/stdlib/Atomics.swift

@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -O -emit-sil -disable-availability-checking %s | %IRGenFileCheck %s
+// RUN: %target-swift-frontend -enable-ossa-modules -O -emit-sil -disable-availability-checking %s | %IRGenFileCheck %s
 
 // REQUIRES: synchronization