[SIL] [Immediate] Promote linkage of SILFunctions defining requested symbols

Promotes the linkage of `SILFunction`s defining requested symbols,
ensuring they are emitted during IRGen.

Author: Zak Kent

include/swift/SIL/SILModule.h

@@ -737,6 +737,12 @@ class SILModule {
     return isPossiblyUsedExternally(getDeclSILLinkage(decl), isWholeModule());
   }
 
+  /// Promote the linkage of every entity in this SIL module so that they are
+  /// externally visible. This is used to promote the linkage of private
+  /// entities that are compiled on-demand for lazy immediate mode, as each is
+  /// emitted into its own `SILModule`.
+  void promoteLinkages();
+
   PropertyListType &getPropertyList() { return properties; }
   const PropertyListType &getPropertyList() const { return properties; }
 

lib/Immediate/SwiftMaterializationUnit.cpp

@@ -301,12 +301,9 @@ LazySwiftMaterializationUnit::Create(SwiftJIT &JIT, CompilerInstance &CI) {
     if (Source.kind != SymbolSource::Kind::SIL) {
       continue;
     }
-    auto Ref = Source.getSILDeclRef();
     const auto &SymbolName = Entry.getKey();
-    auto Flags = llvm::JITSymbolFlags::Callable;
-    if (Ref.getDefinitionLinkage() == SILLinkage::Public) {
-      Flags |= llvm::JITSymbolFlags::Exported;
-    }
+    auto Flags =
+        llvm::JITSymbolFlags::Callable | llvm::JITSymbolFlags::Exported;
     auto MangledName = mangle(SymbolName);
     PublicInterface[JIT.intern(MangledName)] = Flags;
   }
@@ -345,6 +342,12 @@ void LazySwiftMaterializationUnit::materialize(
     Refs.push_back(std::move(Ref));
   }
   auto SM = performASTLowering(CI, std::move(Refs));
+
+  // Promote linkages of SIL entities
+  // defining requested symbols so they are
+  // emitted during IRGen.
+  SM->promoteLinkages();
+
   runSILDiagnosticPasses(*SM);
   runSILLoweringPasses(*SM);
   auto GM = generateModule(CI, std::move(SM));

lib/SIL/IR/SILModule.cpp

@@ -864,6 +864,14 @@ void SILModule::installSILRemarkStreamer() {
   silRemarkStreamer = SILRemarkStreamer::create(*this);
 }
 
+void SILModule::promoteLinkages() {
+  for (auto &Fn : functions)
+    if (Fn.isDefinition())
+      Fn.setLinkage(SILLinkage::Public);
+
+  // TODO: Promote linkage of other SIL entities
+}
+
 bool SILModule::isStdlibModule() const {
   return TheSwiftModule->isStdlibModule();
 }