Merge pull request #71105 from DougGregor/silgen-hack-distributed-actor-as-actor

[SILGen] Ensure that we emit the distributed-actor-as-actor conformance

Author: DougGregor

include/swift/AST/KnownIdentifiers.def

@@ -32,6 +32,7 @@ IDENTIFIER(accumulated)
 IDENTIFIER(ActorType)
 IDENTIFIER(Any)
 IDENTIFIER(ArrayLiteralElement)
+IDENTIFIER(asLocalActor)
 IDENTIFIER(atIndexedSubscript)
 IDENTIFIER_(bridgeToObjectiveC)
 IDENTIFIER(buildArray)

lib/SILGen/SILGen.h

@@ -83,6 +83,10 @@ class LLVM_LIBRARY_VISIBILITY SILGenModule : public ASTVisitor<SILGenModule> {
   /// Set of delayed conformances that have already been forced.
   llvm::DenseSet<NormalProtocolConformance *> forcedConformances;
 
+  /// The conformance for any DistributedActor to the Actor protocol,
+  /// used only by the `distributedActorAsAnyActor` builtin.
+  RootProtocolConformance *distributedActorAsActorConformance = nullptr;
+
   size_t anonymousSymbolCounter = 0;
 
   llvm::Optional<SILDeclRef> StringToNSStringFn;
@@ -605,6 +609,20 @@ class LLVM_LIBRARY_VISIBILITY SILGenModule : public ASTVisitor<SILGenModule> {
   /// mentioned by the given type.
   void useConformancesFromObjectiveCType(CanType type);
 
+  /// Retrieve a protocol conformance to the `Actor` protocol for a
+  /// distributed actor type that is described via a substitution map for
+  /// the generic signature `<T: DistributedActor>`.
+  ///
+  /// The protocol conformance is a special one that is currently
+  /// only used by the `distributedActorAsAnyActor` builtin.
+  ProtocolConformanceRef
+  getDistributedActorAsActorConformance(SubstitutionMap subs);
+
+  /// Make a note of a member reference expression, which allows us
+  /// to ensure that the conformance above is emitted wherever it
+  /// needs to be.
+  void noteMemberRefExpr(MemberRefExpr *e);
+
   /// Map the substitutions for the original declaration to substitutions for
   /// the overridden declaration.
   static SubstitutionMap mapSubstitutionsForWitnessOverride(

lib/SILGen/SILGenBuiltin.cpp

@@ -1889,13 +1889,10 @@ static ManagedValue emitBuiltinInjectEnumTag(SILGenFunction &SGF, SILLocation lo
   return ManagedValue::forObjectRValueWithoutOwnership(bi);
 }
 
-static ExtensionDecl *distributedActorAsAnyActorExt = nullptr;
-
 /// Find the extension on DistributedActor that defines __actorUnownedExecutor.
 static ExtensionDecl *findDistributedActorAsActorExtension(
     ProtocolDecl *distributedActorProto, ModuleDecl *module) {
   ASTContext &ctx = distributedActorProto->getASTContext();
-  #if true
   auto name = ctx.getIdentifier("__actorUnownedExecutor");
   auto results = distributedActorProto->lookupDirect(
       name, SourceLoc(),
@@ -1907,53 +1904,73 @@ static ExtensionDecl *findDistributedActorAsActorExtension(
   }
 
   return nullptr;
-  #else
-  if (!distributedActorAsAnyActorExt) {
-    auto ext = ExtensionDecl::create(
-        ctx, SourceLoc(), nullptr, { }, module, nullptr);
-    ctx.evaluator.cacheOutput(ExtendedTypeRequest{ext},
-                              distributedActorProto->getDeclaredInterfaceType());
-    ctx.evaluator.cacheOutput(ExtendedNominalRequest{ext},
-                              distributedActorProto);
-
-    distributedActorAsAnyActorExt = ext;
+}
+
+ProtocolConformanceRef
+SILGenModule::getDistributedActorAsActorConformance(SubstitutionMap subs) {
+  ASTContext &ctx = M.getASTContext();
+  auto actorProto = ctx.getProtocol(KnownProtocolKind::Actor);
+  Type distributedActorType = subs.getReplacementTypes()[0];
+
+  if (!distributedActorAsActorConformance) {
+    auto distributedActorProto = ctx.getProtocol(KnownProtocolKind::DistributedActor);
+    if (!distributedActorProto)
+      return ProtocolConformanceRef();
+
+    auto ext = findDistributedActorAsActorExtension(
+        distributedActorProto, M.getSwiftModule());
+    if (!ext)
+      return ProtocolConformanceRef();
+
+    // Conformance of DistributedActor to Actor.
+    auto genericParam = subs.getGenericSignature().getGenericParams()[0];
+    distributedActorAsActorConformance = ctx.getNormalConformance(
+        Type(genericParam), actorProto, SourceLoc(), ext,
+        ProtocolConformanceState::Incomplete, /*isUnchecked=*/false,
+        /*isPreconcurrency=*/false);
+  }
+
+  return ProtocolConformanceRef(
+      actorProto,
+      ctx.getSpecializedConformance(distributedActorType,
+                                    distributedActorAsActorConformance,
+                                    subs));
+}
+
+void SILGenModule::noteMemberRefExpr(MemberRefExpr *e) {
+  VarDecl *var = cast<VarDecl>(e->getMember().getDecl());
+
+  // If the member is the special `asLocalActor` operation on
+  // distributed actors, make sure we have the conformance needed
+  // for a builtin.
+  ASTContext &ctx = var->getASTContext();
+  if (var->getName() == ctx.Id_asLocalActor &&
+      var->getDeclContext()->getSelfProtocolDecl() &&
+      var->getDeclContext()->getSelfProtocolDecl()
+          ->isSpecificProtocol(KnownProtocolKind::DistributedActor)) {
+    auto conformance =
+        getDistributedActorAsActorConformance(
+          e->getMember().getSubstitutions());
+    useConformance(conformance);
   }
 
-  return distributedActorAsAnyActorExt;
-  #endif
 }
 
 static ManagedValue emitBuiltinDistributedActorAsAnyActor(
     SILGenFunction &SGF, SILLocation loc, SubstitutionMap subs,
     ArrayRef<ManagedValue> args, SGFContext C) {
   auto &ctx = SGF.getASTContext();
   auto distributedActor = args[0];
-
-  auto builtinDecl = cast<FuncDecl>(getBuiltinValueDecl(
-      ctx, ctx.getIdentifier("distributedActorAsAnyActor")));
-  auto genericSignature = builtinDecl->getGenericSignature();
-  auto genericParam = genericSignature.getGenericParams()[0];
-
-  auto distributedActorProto = ctx.getProtocol(KnownProtocolKind::DistributedActor);
-  auto ext = findDistributedActorAsActorExtension(
-      distributedActorProto, SGF.getModule().getSwiftModule());
-
-  // Conformance of DistributedActor to Actor.
-  auto actorProto = ctx.getProtocol(KnownProtocolKind::Actor);
-  CanType distributedActorType = distributedActor.getType().getASTType();
-  RootProtocolConformance *daAsActorConformance = ctx.getNormalConformance(
-      Type(genericParam), actorProto, SourceLoc(), ext,
-      ProtocolConformanceState::Incomplete, /*isUnchecked=*/false,
-      /*isPreconcurrency=*/false);
-  ProtocolConformanceRef conformance(
-      actorProto,
-      ctx.getSpecializedConformance(distributedActorType, daAsActorConformance,
-                                    subs));
-  ProtocolConformanceRef conformances[1] = { conformance };
+  ProtocolConformanceRef conformances[1] = {
+    SGF.SGM.getDistributedActorAsActorConformance(subs)
+  };
 
   // Erase the distributed actor instance into an `any Actor` existential with
   // the special conformance.
+  CanType distributedActorType =
+      subs.getReplacementTypes()[0]->getCanonicalType();
   auto &distributedActorTL = SGF.getTypeLowering(distributedActorType);
+  auto actorProto = ctx.getProtocol(KnownProtocolKind::Actor);
   auto &anyActorTL = SGF.getTypeLowering(actorProto->getDeclaredExistentialType());
   return SGF.emitExistentialErasure(
       loc, distributedActorType, distributedActorTL, anyActorTL, 

lib/SILGen/SILGenLValue.cpp

@@ -3055,6 +3055,9 @@ class LLVM_LIBRARY_VISIBILITY SILGenBorrowedBaseVisitor
                              options, e->isSuper(), accessKind, strategy,
                              getSubstFormalRValueType(e),
                              false /*is on self parameter*/, actorIso);
+
+    SGF.SGM.noteMemberRefExpr(e);
+
     return lv;
   }
 
@@ -3864,6 +3867,9 @@ LValue SILGenLValue::visitMemberRefExpr(MemberRefExpr *e,
   lv.addMemberVarComponent(SGF, e, var, e->getMember().getSubstitutions(),
                            options, e->isSuper(), accessKind, strategy,
                            substFormalRValueType, isOnSelfParameter, actorIso);
+
+  SGF.SGM.noteMemberRefExpr(e);
+
   return lv;
 }
 

lib/Sema/TypeCheckConcurrency.cpp

@@ -3465,7 +3465,7 @@ namespace {
         // actor.
         if (isolation.isDistributedActor()) {
           actorExpr = UnresolvedDotExpr::createImplicit(
-              ctx, actorExpr, ctx.getIdentifier("asLocalActor"));
+              ctx, actorExpr, ctx.Id_asLocalActor);
         }
         break;
       }

test/Distributed/Runtime/distributed_actor_to_actor.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend-emit-module -emit-module-path %t/FakeDistributedActorSystems.swiftmodule -module-name FakeDistributedActorSystems %S/../Inputs/FakeDistributedActorSystems.swift
-// RUN: %target-build-swift -module-name main %import-libdispatch -j2 -parse-as-library -Xfrontend -disable-availability-checking -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -g -o %t/a.out -enable-experimental-feature BuiltinModule
+// RUN: %target-build-swift -module-name main %import-libdispatch -j2 -parse-as-library -Xfrontend -disable-availability-checking -I %t %s %S/../Inputs/FakeDistributedActorSystems.swift -g -o %t/a.out
 // RUN: %target-codesign %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s --color
 
@@ -16,21 +16,12 @@
 // FIXME(distributed): Distributed actors currently have some issues on windows rdar://82593574
 // UNSUPPORTED: OS=windows-msvc
 
-import Builtin // FIXME: Part of a hack to get the protocol conformance defined properly
 import Dispatch
 import Distributed
 import FakeDistributedActorSystems
 
 typealias DefaultDistributedActorSystem = FakeRoundtripActorSystem
 
-extension DistributedActor {
-  func localDistributedAsActor() -> any Actor {
-    // FIXME: Part of a hack that forces the protocol conformance for DistributedActor -> Actor to be defined
-    // FIXME: Drop usage of this once we resolve the issue above
-    Builtin.distributedActorAsAnyActor(self)
-  }
-}
-
 distributed actor Worker {
   var counter: Int = 0