Add linkWitnessTable to SILModule, use in Link.cpp

Author: MaxDesiatov

include/swift/SIL/SILModule.h

@@ -867,6 +867,11 @@ class SILModule {
   /// Returns true if linking succeeded, false otherwise.
   bool linkFunction(SILFunction *F, LinkingMode LinkMode);
 
+  /// Attempt to deserialize witness table for protocol conformance \p PC.
+  ///
+  /// Returns true if linking succeeded, false otherwise.
+  bool linkWitnessTable(ProtocolConformance *PC, LinkingMode LinkMode);
+
   /// Check if a given function exists in any of the modules.
   /// i.e. it can be linked by linkFunction.
   bool hasFunction(StringRef Name);

lib/SIL/IR/SILModule.cpp

@@ -433,6 +433,10 @@ bool SILModule::linkFunction(SILFunction *F, SILModule::LinkingMode Mode) {
   return SILLinkerVisitor(*this, Mode).processFunction(F);
 }
 
+bool SILModule::linkWitnessTable(ProtocolConformance *PC, SILModule::LinkingMode Mode) {
+  return SILLinkerVisitor(*this, Mode).processConformance(ProtocolConformanceRef(PC));
+}
+
 bool SILModule::hasFunction(StringRef Name) {
   if (lookUpFunction(Name))
     return true;

lib/SILOptimizer/UtilityPasses/Link.cpp

@@ -105,7 +105,7 @@ class SILLinker : public SILModuleTransform {
                            SILLinkage::HiddenExternal);
     linkUsedFunctionByName("swift_createDefaultExecutors",
                            SILLinkage::HiddenExternal);
-    linkEmbeddedRuntimeWitnessTable();
+    linkEmbeddedRuntimeWitnessTables();
   }
 
   void linkEmbeddedRuntimeFunctionByName(StringRef name,
@@ -124,20 +124,16 @@ class SILLinker : public SILModuleTransform {
     linkUsedFunctionByName(name, SILLinkage::PublicExternal);
   }
 
-  void linkEmbeddedRuntimeWitnessTable() {
+  void linkEmbeddedRuntimeWitnessTables() {
     SILModule &M = *getModule();
 
     auto *mainActor = M.getASTContext().getMainActorDecl();
     if (mainActor) {
       for (auto *PC : mainActor->getAllConformances()) {
         auto *ProtoDecl = PC->getProtocol();
-        auto name = ProtoDecl->getName();
-        if (name.str() == "Actor") {
-          auto &e = llvm::errs();
-          e << "Found MainActor: Actor conformance\n";
+        if (ProtoDecl->getName().str() == "Actor") {
+          M.linkWitnessTable(PC, SILModule::LinkingMode::LinkAll);
           if (auto *WT = M.lookUpWitnessTable(PC)) {
-            WT = M.getSILLoader()->lookupWitnessTable(WT);
-            e << "Looked up MainActor: Actor witness table\n";
             WT->setLinkage(SILLinkage::Public);
           }
         }