[4.2] IRGen: Don't pass metadata of not ABI accessible to outlined copy/destroy operations

Doing so will cause linkage errors and is not neccessary since we call
the witness of the enclosing type as soon as its fields are not ABI
accessible.

rdar://40868358

Author: aschwaighofer

lib/IRGen/Outlining.cpp

@@ -36,7 +36,11 @@ void OutliningMetadataCollector::collectTypeMetadataForLayout(SILType type) {
   }
 
   CanType formalType = type.getSwiftRValueType();
-  if (isa<FixedTypeInfo>(IGF.IGM.getTypeInfoForLowered(formalType))) {
+  auto &ti = IGF.IGM.getTypeInfoForLowered(formalType);
+  // We don't need the metadata for fixed size types or types that are not ABI
+  // accessible. Outlining will call the value witness of the enclosing type of
+  // non ABI accessible field/element types.
+  if (isa<FixedTypeInfo>(ti) || !ti.isABIAccessible()) {
     return;
   }
 

test/IRGen/Inputs/ABIInaccessible.swift

@@ -0,0 +1,13 @@
+private struct Private<T> {
+  init(_ t: T) {
+    p = t
+  }
+  var p : T
+}
+
+public struct Public<T> {
+  init(_ t: T) {
+    p = Private<T>(t)
+  }
+  private var p: Private<T>
+}

test/IRGen/TestABIInaccessible.swift

@@ -0,0 +1,20 @@
+// RUN: %target-swift-frontend -module-name main -I %t -emit-ir -primary-file %s %S/Inputs/ABIInaccessible.swift | %FileCheck %s
+
+public struct AnotherType<T> {
+  init(_ t: T) {
+    p = Public<T>(t)
+  }
+  public var p : Public<T>
+}
+
+// Don't pass the metadata of Private<T> to AnotherType<T>'s outlined destroy.
+// CHECK-LABEL: define swiftcc void @"$S4main4copyyAA11AnotherTypeVyxGAElF"(%T4main11AnotherTypeV* noalias nocapture sret, %T4main11AnotherTypeV* noalias nocapture, %swift.type* %T)
+// CHECK:  [[MD:%.*]] = call swiftcc %swift.metadata_response @"$S4main11AnotherTypeVMa"(i{{.*}} 0, %swift.type* %T) #9
+// CHECK:  [[MD1:%.*]] = extractvalue %swift.metadata_response %3, 0
+// CHECK:  [[MD2:%.*]] = call swiftcc %swift.metadata_response @"$S4main6PublicVMa"(i{{.*}} 0, %swift.type* %T)
+// CHECK:  [[MD3:%.*]] = extractvalue %swift.metadata_response %10, 0
+// CHECK:  call %T4main11AnotherTypeV* @"$S4main11AnotherTypeVyxGlWOc"(%T4main11AnotherTypeV* %1, %T4main11AnotherTypeV* {{.*}}, %swift.type* %T, %swift.type* [[MD3]], %swift.type* [[MD1]])
+public func copy<T>(_ a: AnotherType<T>) -> AnotherType<T> {
+  let copy = a
+  return copy
+}