Merge pull request #60048 from xedin/keep-alive-for-se-360

[SIL] Keep alive `@_alwaysEmitIntoClient` decls with opaque result types

Author: xedin

include/swift/SIL/SILFunction.h

@@ -1121,6 +1121,32 @@ class SILFunction
     return false;
   }
 
+  /// Returns true if this function belongs to a declaration that
+  /// has `@_alwaysEmitIntoClient` attribute.
+  bool markedAsAlwaysEmitIntoClient() const {
+    if (!hasLocation())
+      return false;
+
+    auto *V = getLocation().getAsASTNode<ValueDecl>();
+    return V && V->getAttrs().hasAttribute<AlwaysEmitIntoClientAttr>();
+  }
+
+  /// Returns true if this function belongs to a declaration that returns
+  /// an opaque result type with one or more availability conditions that are
+  /// allowed to produce a different underlying type at runtime.
+  bool hasOpaqueResultTypeWithAvailabilityConditions() const {
+    if (!hasLocation())
+      return false;
+
+    if (auto *V = getLocation().getAsASTNode<ValueDecl>()) {
+      auto *opaqueResult = V->getOpaqueResultTypeDecl();
+      return opaqueResult &&
+             opaqueResult->hasConditionallyAvailableSubstitutions();
+    }
+
+    return false;
+  }
+
   //===--------------------------------------------------------------------===//
   // Block List Access
   //===--------------------------------------------------------------------===//

lib/IRGen/IRGenSIL.cpp

@@ -2232,18 +2232,15 @@ void IRGenSILFunction::emitSILFunction() {
     IGM.IRGen.addDynamicReplacement(CurSILFn);
 
   if (CurSILFn->getLinkage() == SILLinkage::Shared) {
-    if (auto *V = CurSILFn->getLocation().getAsASTNode<ValueDecl>()) {
-      bool alwaysEmitIntoClient =
-          V->getAttrs().hasAttribute<AlwaysEmitIntoClientAttr>();
+    if (CurSILFn->markedAsAlwaysEmitIntoClient() &&
+        CurSILFn->hasOpaqueResultTypeWithAvailabilityConditions()) {
+      auto *V = CurSILFn->getLocation().castToASTNode<ValueDecl>();
       auto *opaqueResult = V->getOpaqueResultTypeDecl();
       // `@_alwaysEmitIntoClient` declaration with opaque result
       // has to emit opaque type descriptor into client module
       // when it has availability conditions because the underlying
       // type in such cases is unknown until runtime.
-      if (alwaysEmitIntoClient && opaqueResult &&
-          opaqueResult->hasConditionallyAvailableSubstitutions()) {
-        IGM.maybeEmitOpaqueTypeDecl(opaqueResult);
-      }
+      IGM.maybeEmitOpaqueTypeDecl(opaqueResult);
     }
   }
 

lib/SIL/IR/SILFunction.cpp

@@ -708,6 +708,13 @@ SILFunction::isPossiblyUsedExternally() const {
   if (isDistributed() && isThunk())
     return true;
 
+  // Declaration marked as `@_alwaysEmitIntoClient` that
+  // returns opaque result type with availability conditions
+  // has to be kept alive to emit opaque type metadata descriptor.
+  if (markedAsAlwaysEmitIntoClient() &&
+      hasOpaqueResultTypeWithAvailabilityConditions())
+    return true;
+
   return swift::isPossiblyUsedExternally(linkage, getModule().isWholeModule());
 }