Cross-module-optimization: no need to add AST-attributes to make functions always-emit-into-client.

This is less hacky and possible now, as we de-serialize the linkage from SIL (and not just derive it from the AST attributes).

Author: eeckstein

lib/SILOptimizer/IPO/CrossModuleSerializationSetup.cpp

@@ -61,8 +61,6 @@ class CrossModuleSerializationSetup {
 
   void makeSubstUsableFromInline(const SubstitutionMap &substs);
 
-  bool markAsEmitIntoClient(SILFunction *F);
-
 public:
   CrossModuleSerializationSetup(SILModule &M) : M(M) { }
 
@@ -313,12 +311,7 @@ void CrossModuleSerializationSetup::scanModule() {
 
         // As a code size optimization, make serialized functions
         // @alwaysEmitIntoClient.
-        if (!markAsEmitIntoClient(F)) {
-          // We don't have a declaration to put the attribute on (e.g. in case
-          // the function is a closure). Just make the function public instead
-          // of @alwaysEmitIntoClient.
-          F->setLinkage(SILLinkage::Public);
-        }
+        F->setLinkage(SILLinkage::PublicNonABI);
       } else {
         // If for some reason the function cannot be serialized, we mark it as
         // usable-from-inline.
@@ -328,36 +321,6 @@ void CrossModuleSerializationSetup::scanModule() {
   }
 }
 
-/// Marks a function as @alwaysEmitIntoClient and returns true if this is
-/// successful.
-bool CrossModuleSerializationSetup::markAsEmitIntoClient(SILFunction *F) {
-  auto *DC = F->getDeclContext();
-  if (!DC)
-    return false;
-
-  Decl *decl = DC->getAsDecl();
-  if (!decl)
-    return false;
-
-  if (!isa<AbstractFunctionDecl>(decl))
-    return false;
-
-  F->setLinkage(SILLinkage::PublicNonABI);
-
-  // Adding the attribute is only needed to be able to compile the
-  // client module with -Onone. For optimized builds, setting the
-  // SILLinkage is enough, because with optimization, the client module
-  // eagerly de-serializes all functions and therefore gets the
-  // linkage right. But with -Onone, the linkage is derived purly from
-  // the AST.
-  // TODO: also here, we should find a way to not modify the AST.
-  auto &ctx = M.getASTContext();
-  auto *attr = new (ctx) AlwaysEmitIntoClientAttr(/*implicit=*/true);
-  decl->getAttrs().add(attr);
-
-  return true;
-}
-
 class CrossModuleSerializationSetupPass: public SILModuleTransform {
   void run() override {
 

test/SILOptimizer/Inputs/cross-module.swift

@@ -92,6 +92,11 @@ private protocol PrivateProtocol {
 
 open class OpenClass<T> {
   public init() { }
+
+  @inline(never)
+  fileprivate func bar(_ t: T) {
+    print(t)
+  }
 }
 
 extension OpenClass {
@@ -114,6 +119,12 @@ public func checkIfClassConforms_gen<T>(_ t: T) {
   print(x.testit())
 }
 
+@inline(never)
+public func callClassMethod<T>(_ t: T) {
+  let k = OpenClass<T>()
+  k.bar(t)
+}
+
 extension Int : PrivateProtocol {
   func foo() -> Int { return self }
 }

test/SILOptimizer/cross-module-optimization.swift

@@ -64,7 +64,9 @@ func testError() {
   print(returnInternalError(27))
 }
 
-func testProtocol() {
+class DerivedFromOpen<T> : OpenClass<T> { }
+
+func testProtocolsAndClasses() {
   // CHECK-OUTPUT: false
   // CHECK-SIL-DAG: sil shared [noinline] @$s4Test20checkIfClassConformsyyxlFSi_Tg5
   checkIfClassConforms(27)
@@ -80,6 +82,8 @@ func testProtocol() {
   // CHECK-OUTPUT: 1234
   // CHECK-SIL-DAG: sil shared_external {{.*}} @$s4Test11callFoo_genyyxlF
   callFoo_gen(27)
+  // CHECK-OUTPUT: 55
+  callClassMethod(55)
 }
 
 func testSubModule() {
@@ -111,7 +115,7 @@ func testKeypath() {
 testNestedTypes()
 testClass()
 testError()
-testProtocol()
+testProtocolsAndClasses()
 testSubModule()
 testClosures()
 testKeypath()