Refine The Frontend's Understanding of SwiftOnoneSupport

include/swift/Frontend/FrontendOptions.h

@@ -310,7 +310,7 @@ class FrontendOptions {
   static bool canActionEmitInterface(ActionType);
 
 public:
-  static bool doesActionRunSILPasses(ActionType);
+  static bool doesActionGenerateSIL(ActionType);
   static bool doesActionProduceOutput(ActionType);
   static bool doesActionProduceTextualOutput(ActionType);
   static bool needsProperModuleName(ActionType);

lib/Frontend/Frontend.cpp

@@ -413,14 +413,21 @@ shouldImplicityImportSwiftOnoneSupportModule(CompilerInvocation &Invocation) {
   if (Invocation.getSILOptions().shouldOptimize())
     return false;
 
-  // If we are not going through the SIL Optimizer with the
-  // given frontend action, do not load SwiftOnoneSupport.
+  // If we are not executing an action that has a dependency on
+  // SwiftOnoneSupport, don't load it.
+  //
+  // FIXME: Knowledge of SwiftOnoneSupport loading in the Frontend is a layering
+  // violation. However, SIL currently does not have a way to express this
+  // dependency itself for the benefit of autolinking.  In the mean time, we
+  // will be conservative and say that actions like -emit-silgen and
+  // -emit-sibgen - that don't really involve the optimizer - have a
+  // strict dependency on SwiftOnoneSupport.
   //
   // This optimization is disabled by -track-system-dependencies to preserve
   // the explicit dependency.
   const auto &options = Invocation.getFrontendOptions();
   return options.TrackSystemDeps
-      || FrontendOptions::doesActionRunSILPasses(options.RequestedAction);
+      || FrontendOptions::doesActionGenerateSIL(options.RequestedAction);
 }
 
 void CompilerInstance::performParseAndResolveImportsOnly() {

lib/Frontend/FrontendOptions.cpp

@@ -465,7 +465,7 @@ bool FrontendOptions::doesActionProduceTextualOutput(ActionType action) {
   }
 }
 
-bool FrontendOptions::doesActionRunSILPasses(ActionType action) {
+bool FrontendOptions::doesActionGenerateSIL(ActionType action) {
   switch (action) {
   case ActionType::NoneAction:
   case ActionType::Parse:
@@ -478,22 +478,22 @@ bool FrontendOptions::doesActionRunSILPasses(ActionType action) {
   case ActionType::PrintAST:
   case ActionType::DumpScopeMaps:
   case ActionType::DumpTypeRefinementContexts:
-  case ActionType::DumpTypeInfo:
   case ActionType::EmitImportedModules:
   case ActionType::EmitPCH:
-  case ActionType::EmitSILGen:
     return false;
+  case ActionType::EmitSILGen:
+  case ActionType::EmitSIBGen:
   case ActionType::EmitSIL:
+  case ActionType::EmitSIB:
   case ActionType::EmitModuleOnly:
   case ActionType::MergeModules:
-  case ActionType::EmitSIBGen:
-  case ActionType::EmitSIB:
   case ActionType::Immediate:
   case ActionType::REPL:
   case ActionType::EmitAssembly:
   case ActionType::EmitIR:
   case ActionType::EmitBC:
   case ActionType::EmitObject:
+  case ActionType::DumpTypeInfo:
     return true;
   }
 }

lib/FrontendTool/FrontendTool.cpp

@@ -996,7 +996,7 @@ static bool performCompile(CompilerInstance &Instance,
   if (writeTBDIfNeeded(Invocation, Instance))
     return true;
 
-  assert(Action >= FrontendOptions::ActionType::EmitSILGen &&
+  assert(FrontendOptions::doesActionGenerateSIL(Action) &&
          "All actions not requiring SILGen must have been handled!");
 
   std::deque<PostSILGenInputs> PSGIs = generateSILModules(Invocation, Instance);

test/Driver/emit-sib-single-file.swift

@@ -18,6 +18,9 @@
 // CHECK: Hello World
 // CHECK: Hello Bob, today is Tuesday.
 
+// This test intentionally mirrors /Driver/emit-sil-single-file to ensure that
+// SwiftOnoneSupport is always a dependency of -Onone -emit-si*gen builds.
+
 @inlinable
 @usableFromInline
 func greet(_ name: String, _ day: String) -> String {

test/Driver/emit-sil-single-file.swift

@@ -0,0 +1,28 @@
+// RUN: %target-build-swift -Onone -emit-silgen %s -o %t.sil
+// RUN: %target-build-swift -parse-sil %t.sil -o %t
+// RUN: %target-run %t | %FileCheck %s
+
+// RUN: %target-build-swift -Onone -c %t.sil -o %t.o
+// RUN: %target-build-swift %t.o -o %t
+// RUN: %target-run %t | %FileCheck %s
+// REQUIRES: executable_test
+
+// CHECK: Hello World
+// CHECK: Hello Bob, today is Tuesday.
+
+// This test intentionally mirrors /Driver/emit-sib-single-file to ensure that
+// SwiftOnoneSupport is always a dependency of -Onone -emit-si*gen builds.
+
+// FIXME: The Frontend's understanding of the situations in which to load
+// SwiftOnoneSupport is a tacit part of the rest of the compile pipeline and
+// pervades the AST.  SIL could probably sink knowledge of module dependencies
+// internally and make this test unnecessary.
+
+@inlinable
+@usableFromInline
+func greet(_ name: String, _ day: String) -> String {
+  return "Hello \(name), today is \(day)."
+}
+
+print("Hello World")
+print(greet("Bob", "Tuesday"))