SILGen: Honor -experimental-skip-non-exportable-decls.

When the flag is specified, only emit SIL for declarations that are exposed to
clients.

Resolves rdar://116774565

Author: tshortli

lib/SILGen/SILGen.cpp

@@ -801,6 +801,10 @@ bool SILGenModule::shouldSkipDecl(Decl *D) {
   if (!D->isAvailableDuringLowering())
     return true;
 
+  if (getASTContext().SILOpts.SkipNonExportableDecls &&
+      !D->isExposedToClients())
+    return true;
+
   return false;
 }
 
@@ -1419,6 +1423,8 @@ void SILGenModule::emitAbstractFuncDecl(AbstractFunctionDecl *AFD) {
 }
 
 void SILGenModule::emitFunction(FuncDecl *fd) {
+  assert(!shouldSkipDecl(fd));
+
   Types.setCaptureTypeExpansionContext(SILDeclRef(fd), M);
 
   SILDeclRef::Loc decl = fd;

lib/SILGen/SILGenType.cpp

@@ -47,6 +47,9 @@ SILGenModule::emitVTableMethod(ClassDecl *theClass, SILDeclRef derived,
   auto *baseDecl = cast<AbstractFunctionDecl>(base.getDecl());
   auto *derivedDecl = cast<AbstractFunctionDecl>(derived.getDecl());
 
+  if (shouldSkipDecl(baseDecl))
+    return llvm::None;
+
   // Note: We intentionally don't support extension members here.
   //
   // Once extensions can override or introduce new vtable entries, this will

test/SILGen/skip-non-exportable-decls.swift

@@ -0,0 +1,64 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend -emit-silgen %s -parse-as-library -module-name Test | %FileCheck %s --check-prefixes=CHECK,CHECK-NO-SKIP
+// RUN: %target-swift-frontend -emit-silgen %s -parse-as-library -module-name Test -experimental-skip-non-exportable-decls | %FileCheck %s --check-prefixes=CHECK,CHECK-SKIP
+
+// CHECK-NO-SKIP: sil private{{.*}} @$s4Test11privateFunc33_E3F0E1C7B46D05C8067CB98677DE566CLLyyF : $@convention(thin) () -> () {
+// CHECK-SKIP-NOT: s4Test11privateFunc33_E3F0E1C7B46D05C8067CB98677DE566CLLyyF
+private func privateFunc() {}
+
+// CHECK-NO-SKIP: sil hidden{{.*}} @$s4Test12internalFuncyyF : $@convention(thin) () -> () {
+// CHECK-SKIP-NOT: s4Test12internalFuncyyF
+internal func internalFunc() {}
+
+// CHECK: sil{{.*}} @$s4Test10publicFuncyyF : $@convention(thin) () -> () {
+public func publicFunc() {}
+
+private class PrivateClass {
+  // CHECK-NO-SKIP: sil private{{.*}} @$s4Test12PrivateClass33_E3F0E1C7B46D05C8067CB98677DE566CLLCfd : $@convention(method) (@guaranteed PrivateClass) -> @owned Builtin.NativeObject {
+  // CHECK-SKIP-NOT: s4Test12PrivateClass33_E3F0E1C7B46D05C8067CB98677DE566CLLCfd
+
+  // CHECK-NO-SKIP: sil private{{.*}} @$s4Test12PrivateClass33_E3F0E1C7B46D05C8067CB98677DE566CLLCfD : $@convention(method) (@owned PrivateClass) -> () {
+  // CHECK-SKIP-NOT: s4Test12PrivateClass33_E3F0E1C7B46D05C8067CB98677DE566CLLCfD
+
+  // CHECK-NO-SKIP: sil private{{.*}} @$s4Test12PrivateClass33_E3F0E1C7B46D05C8067CB98677DE566CLLCADycfC : $@convention(method) (@thick PrivateClass.Type) -> @owned PrivateClass {
+  // CHECK-SKIP-NOT: s4Test12PrivateClass33_E3F0E1C7B46D05C8067CB98677DE566CLLCADycfC
+
+  // CHECK-NO-SKIP: sil private{{.*}} @$s4Test12PrivateClass33_E3F0E1C7B46D05C8067CB98677DE566CLLCADycfc : $@convention(method) (@owned PrivateClass) -> @owned PrivateClass {
+  // CHECK-SKIP-NOT: s4Test12PrivateClass33_E3F0E1C7B46D05C8067CB98677DE566CLLCADycfc
+}
+
+public class PublicClass {
+  // CHECK-NO-SKIP: sil hidden{{.*}} @$s4Test11PublicClassC14internalMethodyyF : $@convention(method) (@guaranteed PublicClass) -> () {
+  // CHECK-SKIP-NOT: s4Test11PublicClassC14internalMethodyyF
+  internal func internalMethod() {}
+
+  // CHECK: sil{{.*}} @$s4Test11PublicClassCfd : $@convention(method) (@guaranteed PublicClass) -> @owned Builtin.NativeObject {
+
+  // CHECK: sil{{.*}} @$s4Test11PublicClassCfD : $@convention(method) (@owned PublicClass) -> () {
+
+  // CHECK-NO-SKIP: sil hidden{{.*}} @$s4Test11PublicClassCACycfC : $@convention(method) (@thick PublicClass.Type) -> @owned PublicClass {
+  // CHECK-SKIP-NOT: s4Test11PublicClassCACycfC
+
+  // CHECK-NO-SKIP: sil hidden{{.*}} @$s4Test11PublicClassCACycfc : $@convention(method) (@owned PublicClass) -> @owned PublicClass {
+  // CHECK-SKIP-NOT: s4Test11PublicClassCACycfc
+}
+
+extension PublicClass {
+  // CHECK-NO-SKIP: sil hidden{{.*}} @$s4Test11PublicClassC25internalMethodInExtensionyyF : $@convention(method) (@guaranteed PublicClass) -> () {
+  // CHECK-SKIP-NOT: s4Test11PublicClassC25internalMethodInExtensionyyF
+  internal func internalMethodInExtension() {}
+}
+
+// CHECK-NO-SKIP-LABEL: sil_vtable PrivateClass {
+// CHECK-NO-SKIP-NEXT:    #PrivateClass.init!allocator
+// CHECK-NO-SKIP-NEXT:    #PrivateClass.deinit!deallocator
+// CHECK-NO-SKIP-NEXT:  }
+// CHECK-SKIP-NOT:      sil_vtable PrivateClass
+
+// CHECK-LABEL:         sil_vtable [serialized] PublicClass {
+// CHECK-NO-SKIP-NEXT:    #PublicClass.internalMethod
+// CHECK-SKIP-NOT:        #PublicClass.internalMethod
+// CHECK-NO-SKIP-NEXT:    #PublicClass.init!allocator
+// CHECK-SKIP-NOT:        #PublicClass.init!allocator
+// CHECK-NEXT:            #PublicClass.deinit!deallocator
+// CHECK-NEXT:          }