SIL: Don't include convenience initializers in vtables.

They're never dynamically dispatched (unless `required`), so this entry should never be used.

Author: jckarter

include/swift/SIL/SILVTableVisitor.h

@@ -100,10 +100,13 @@ template <class T> class SILVTableVisitor {
       maybeAddEntry(constant, constant.requiresNewVTableEntry());
     }
 
-    // All constructors have their initializing constructor in the
-    // vtable, which can be used by a convenience initializer.
-    SILDeclRef constant(cd, SILDeclRef::Kind::Initializer);
-    maybeAddEntry(constant, constant.requiresNewVTableEntry());
+    // Designated and/or required initializers have their initializing
+    // constructor in the vtable, which can be used by a convenience
+    // initializer.
+    if (cd->isDesignatedInit() || cd->isRequired()) {
+      SILDeclRef constant(cd, SILDeclRef::Kind::Initializer);
+      maybeAddEntry(constant, constant.requiresNewVTableEntry());
+    }
   }
 
   void maybeAddEntry(SILDeclRef declRef, bool needsNewEntry) {

lib/SIL/SILDeclRef.cpp

@@ -49,8 +49,15 @@ swift::getMethodDispatch(AbstractFunctionDecl *method) {
       return MethodDispatch::Static;
 
     // Members defined directly inside a class are dynamically dispatched.
-    if (isa<ClassDecl>(dc))
+    if (isa<ClassDecl>(dc)) {
+      // Convenience initializers are not dynamically dispatched unless
+      // required.
+      if (auto ctor = dyn_cast<ConstructorDecl>(method)) {
+        if (!ctor->isRequired() && ctor->isConvenienceInit())
+          return MethodDispatch::Static;
+      }
       return MethodDispatch::Class;
+    }
 
     // Imported class methods are dynamically dispatched.
     if (method->isObjC() && method->hasClangNode())

test/SILGen/convenience_init_peer_delegation.swift

@@ -0,0 +1,85 @@
+// RUN: %target-swift-emit-silgen %s | %FileCheck %s
+
+class X {
+  init() {
+  }
+
+  // Convenience inits must dynamically dispatch designated inits...
+  // CHECK-LABEL: sil hidden @$S32convenience_init_peer_delegation1XC0A0ACyt_tcfC
+  // CHECK-LABEL: sil hidden @$S32convenience_init_peer_delegation1XC0A0ACyt_tcfc
+  // CHECK:         class_method %7 : $X, #X.init!initializer.1
+  convenience init(convenience: ()) {
+    self.init()
+  }
+
+  // ...but can statically invoke peer convenience inits
+  // CHECK-LABEL: sil hidden @$S32convenience_init_peer_delegation1XC17doubleConvenienceACyt_tcfC
+  // CHECK-LABEL: sil hidden @$S32convenience_init_peer_delegation1XC17doubleConvenienceACyt_tcfc
+  // CHECK:         function_ref @$S32convenience_init_peer_delegation1XC0A0ACyt_tcfc
+  convenience init(doubleConvenience: ()) {
+    self.init(convenience: ())
+  }
+
+  // CHECK-LABEL: sil hidden @$S32convenience_init_peer_delegation1XC8requiredACyt_tcfC
+  // CHECK-LABEL: sil hidden @$S32convenience_init_peer_delegation1XC8requiredACyt_tcfc
+  required init(required: ()) {
+  }
+
+  // CHECK-LABEL: sil hidden @$S32convenience_init_peer_delegation1XC19requiredConvenienceACyt_tcfC
+  // CHECK-LABEL: sil hidden @$S32convenience_init_peer_delegation1XC19requiredConvenienceACyt_tcfc
+  required convenience init(requiredConvenience: ()) {
+    self.init(required: ())
+  }
+
+  // Convenience inits must dynamically dispatch required peer convenience inits
+  // CHECK-LABEL: sil hidden @$S32convenience_init_peer_delegation1XC25requiredDoubleConvenienceACyt_tcfC
+  // CHECK-LABEL: sil hidden @$S32convenience_init_peer_delegation1XC25requiredDoubleConvenienceACyt_tcfc
+  // CHECK:         class_method %7 : $X, #X.init!initializer.1
+  required convenience init(requiredDoubleConvenience: ()) {
+    self.init(requiredDoubleConvenience: ())
+  }
+}
+
+// CHECK-LABEL: sil hidden @$S32convenience_init_peer_delegation11invocations2xtyAA1XCm_tF
+func invocations(xt: X.Type) {
+  // CHECK: function_ref @$S32convenience_init_peer_delegation1XCACycfC
+  _ = X()
+  // CHECK: function_ref @$S32convenience_init_peer_delegation1XC0A0ACyt_tcfC
+  _ = X(convenience: ())
+  // CHECK: function_ref @$S32convenience_init_peer_delegation1XC17doubleConvenienceACyt_tcfC
+  _ = X(doubleConvenience: ())
+  // CHECK: function_ref @$S32convenience_init_peer_delegation1XC8requiredACyt_tcfC
+  _ = X(required: ())
+  // CHECK: function_ref @$S32convenience_init_peer_delegation1XC19requiredConvenienceACyt_tcfC
+  _ = X(requiredConvenience: ())
+  // CHECK: function_ref @$S32convenience_init_peer_delegation1XC25requiredDoubleConvenienceACyt_tcfC
+  _ = X(requiredDoubleConvenience: ())
+
+  // CHECK: class_method %0 : $@thick X.Type, #X.init!allocator.1
+  _ = xt.init(required: ())
+  // CHECK: class_method %0 : $@thick X.Type, #X.init!allocator.1
+  _ = xt.init(requiredConvenience: ())
+  // CHECK: class_method %0 : $@thick X.Type, #X.init!allocator.1
+  _ = xt.init(requiredDoubleConvenience: ())
+}
+
+// CHECK-LABEL: sil_vtable X
+//                -- designated init()
+// CHECK-NOT:     @$S32convenience_init_peer_delegation1XCACycfC
+// CHECK:         @$S32convenience_init_peer_delegation1XCACycfc
+
+//                -- no unrequired convenience inits
+// CHECK-NOT:     @$S32convenience_init_peer_delegation1XC0A0ACyt_tcfC
+// CHECK-NOT:     @$S32convenience_init_peer_delegation1XC0A0ACyt_tcfc
+// CHECK-NOT:     @$S32convenience_init_peer_delegation1XC17doubleConvenienceACyt_tcfC
+// CHECK-NOT:     @$S32convenience_init_peer_delegation1XC17doubleConvenienceACyt_tcfc
+
+//                -- designated init(required:)
+// CHECK:         @$S32convenience_init_peer_delegation1XC8requiredACyt_tcfC
+// CHECK:         @$S32convenience_init_peer_delegation1XC8requiredACyt_tcfc
+//                -- convenience init(requiredConvenience:)
+// CHECK:         @$S32convenience_init_peer_delegation1XC19requiredConvenienceACyt_tcfC
+// CHECK:         @$S32convenience_init_peer_delegation1XC19requiredConvenienceACyt_tcfc
+//                -- convenience init(requiredDoubleConvenience:)
+// CHECK:         @$S32convenience_init_peer_delegation1XC25requiredDoubleConvenienceACyt_tcfC
+// CHECK:         @$S32convenience_init_peer_delegation1XC25requiredDoubleConvenienceACyt_tcfc