test/SILGen/weak.swift

// RUN: %target-swift-frontend -Xllvm -sil-full-demangle -emit-silgen %s | FileCheck %s

class C {
  func f() -> Int { return 42 }
}

func takeClosure(fn: @escaping () -> Int) {}

struct A {
  weak var x: C?
}

// CHECK:    sil hidden @_TF4weak5test0FT1cCS_1C_T_ : $@convention(thin) (@owned C) -> () {
func test0(c c: C) {
  var c = c
// CHECK:    bb0(%0 : $C):
// CHECK:      [[C:%.*]] = alloc_box $C
// CHECK-NEXT: [[PBC:%.*]] = project_box [[C]]

  var a: A
// CHECK:      [[A1:%.*]] = alloc_box $A
// CHECK-NEXT: [[PBA:%.*]] = project_box [[A1]]
// CHECK:      [[A:%.*]] = mark_uninitialized [var] [[PBA]]

  weak var x = c
// CHECK:      [[X:%.*]] = alloc_box $@sil_weak Optional<C>, var, name "x"
// CHECK-NEXT: [[PBX:%.*]] = project_box [[X]]
//   Implicit conversion
// CHECK-NEXT: [[TMP:%.*]] = load [[PBC]] : $*C
// CHECK-NEXT: strong_retain [[TMP]] : $C
// CHECK-NEXT: [[OPTVAL:%.*]] = enum $Optional<C>, #Optional.some!enumelt.1, [[TMP]] : $C
// CHECK-NEXT: store_weak [[OPTVAL]] to [initialization] [[PBX]] : $*@sil_weak Optional<C>
// CHECK-NEXT: release_value [[OPTVAL]] : $Optional<C>

  a.x = c
//   Implicit conversion
// CHECK-NEXT: [[TMP:%.*]] = load [[PBC]] : $*C
// CHECK-NEXT: strong_retain [[TMP]] : $C
// CHECK-NEXT: [[OPTVAL:%.*]] = enum $Optional<C>, #Optional.some!enumelt.1, [[TMP]] : $C

//   Drill to a.x
// CHECK-NEXT: [[A_X:%.*]] = struct_element_addr [[A]] : $*A, #A.x

//   Store to a.x.
// CHECK-NEXT: store_weak [[OPTVAL]] to [[A_X]] : $*@sil_weak Optional<C>
// CHECK-NEXT: release_value [[OPTVAL]] : $Optional<C>
}

// <rdar://problem/16871284> silgen crashes on weak capture
// CHECK: weak.(testClosureOverWeak () -> ()).(closure #1)
// CHECK-LABEL: sil shared @_TFF4weak19testClosureOverWeakFT_T_U_FT_Si : $@convention(thin) (@owned @box @sil_weak Optional<C>) -> Int {
// CHECK: bb0(%0 : $@box @sil_weak Optional<C>):
// CHECK-NEXT:  %1 = project_box %0
// CHECK-NEXT:  debug_value_addr %1 : $*@sil_weak Optional<C>, var, name "bC", argno 1
// CHECK-NEXT:  %3 = alloc_stack $Optional<C>
// CHECK-NEXT:  %4 = load_weak %1 : $*@sil_weak Optional<C>
// CHECK-NEXT:  store %4 to %3 : $*Optional<C>
func testClosureOverWeak() {
  weak var bC = C()
  takeClosure { bC!.f() }
}

class CC {
  weak var x: CC?

  // CHECK-LABEL: sil hidden @_TFC4weak2CCc
  // CHECK:  [[FOO:%.*]] = alloc_box $Optional<CC>
  // CHECK:  [[PB:%.*]] = project_box [[FOO]]
  // CHECK:  [[X:%.*]] = ref_element_addr %2 : $CC, #CC.x
  // CHECK:  [[VALUE:%.*]] = load_weak [[X]] : $*@sil_weak Optional<CC>
  // CHECK:  store [[VALUE]] to [[PB]] : $*Optional<CC>
  init() {
    var foo = x
  }
}