test/SILOptimizer/retain_release_code_motion.sil

// RUN: %target-sil-opt -enable-sil-verify-all -retain-sinking -late-release-hoisting %s | %FileCheck %s
// RUN: %target-sil-opt -enable-sil-verify-all -release-hoisting %s | %FileCheck --check-prefix=CHECK-RELEASE-HOISTING %s
// RUN: %target-sil-opt -enable-sil-verify-all -retain-sinking -retain-sinking -late-release-hoisting %s | %FileCheck --check-prefix=CHECK-MULTIPLE-RS-ROUNDS %s

import Builtin
import Swift

struct Int {
  var value : Builtin.Int64
}

struct Int32 {
  var value : Builtin.Int32
}

struct Int64 {
  var value : Builtin.Int64
}

struct UInt64 {
  var value : Builtin.Int64
}

struct Bool {
  var value : Builtin.Int1
}

struct A {
  var i : Builtin.Int32
}

class fuzz { }

enum Boo {
  case one
  case two
}

class B { }
class E : B { }

class C {}

class C2  {
 var current: A
 init()
}

struct S {
  var ptr : Builtin.NativeObject
}

struct foo {
  var a: Int
  init(a: Int)
  init()
}

enum Optional<T> {
  case none
  case some(T)
}

struct Unowned {
  @_hasStorage unowned let x: @sil_unowned Builtin.NativeObject
}

sil @createS : $@convention(thin) () -> @owned S

sil @use_C2 : $@convention(thin) (C2) -> ()
sil @user : $@convention(thin) (Builtin.NativeObject) -> ()
sil @user_int : $@convention(thin) (Int) -> ()
sil @optional_user : $@convention(thin) (Optional<Builtin.Int32>) -> ()
sil @blocker : $@convention(thin) () -> ()
sil @get_object : $@convention(thin) () -> Builtin.NativeObject
sil @foo_init : $@convention(thin) (@thin foo.Type) -> foo
sil [serialized] @guaranteed_use : $@convention(thin) (@guaranteed Builtin.NativeObject) -> ()
sil [serialized] @guaranteed_throwing_use : $@convention(thin) (@guaranteed Builtin.NativeObject) -> @error Error

// CHECK-LABEL: sil @sink_retains_from_preds : $@convention(thin) (Builtin.NativeObject) -> () {
// CHECK: bb1:
// CHECK-NOT: strong_retain
// CHECK: bb2:
// CHECK-NOT: strong_retain
// CHECK: bb3:
// CHECK: strong_retain
sil @sink_retains_from_preds : $@convention(thin) (Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject):
  strong_release %0 : $Builtin.NativeObject
  cond_br undef, bb1, bb2

bb1:
  strong_retain %0 : $Builtin.NativeObject
  br bb3

bb2:
  strong_retain %0 : $Builtin.NativeObject
  br bb3

bb3:
  %1 = tuple()
  return %1 : $()
}

// CHECK-LABEL: sil @hoist_releases_from_succs : $@convention(thin) (Builtin.NativeObject) -> () {
// CHECK: bb0(
// CHECK: strong_release
// CHECK: bb1:
// CHECK-NOT: strong_release
// CHECK: bb2:
// CHECK-NOT: strong_release
sil @hoist_releases_from_succs : $@convention(thin) (Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject):
  cond_br undef, bb1, bb2

bb1:
  strong_release %0 : $Builtin.NativeObject
  br bb3

bb2:
  strong_release %0 : $Builtin.NativeObject
  br bb3

bb3:
  retain_value %0 : $Builtin.NativeObject
  %1 = tuple()
  return %1 : $()
}

// Make sure that we do not move retains over unreachable terminator.
// CHECK-LABEL: sil @no_return_stops_codemotion : $@convention(thin) (Builtin.NativeObject) -> () {
// CHECK-NOT: strong_retain
// CHECK: } // end sil function 'no_return_stops_codemotion'
sil @no_return_stops_codemotion : $@convention(thin) (Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject):
  %1 = alloc_ref $C
  strong_retain %1 : $C
  unreachable
}

// CHECK-LABEL: sil @retain_blocked_by_maydecrement
// CHECK: strong_retain
// CHECK-NEXT: apply
sil @retain_blocked_by_maydecrement : $@convention(thin) (Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject):
  release_value %0 : $Builtin.NativeObject
  strong_retain %0 : $Builtin.NativeObject
  %2 = function_ref @blocker : $@convention(thin) () -> ()
  apply %2() : $@convention(thin) () -> ()
  br bb1

bb1:
  %1 = tuple()
  return %1 : $()
}

// Make sure release is not hoisted above define.
// CHECK-LABEL: sil @define_stops_codemotion : $@convention(thin) () -> () {
// CHECK: alloc_ref
// CHECK-NEXT: strong_release
sil @define_stops_codemotion : $@convention(thin) () -> () {
bb0:
  %1 = alloc_ref $C
  %2 = tuple()
  strong_release %1 : $C
  %3 = tuple()
  return %3 : $()
}

// Make sure bb3 silargument blocks the release to be hoisted.
// CHECK-LABEL: sil @silargument_stops_codemotion
// CHECK: bb3([[IN:%[0-9]+]] : $C):
// CHECK: release
// CHECK: return
sil @silargument_stops_codemotion : $@convention(thin) () -> () {
bb0:
  %1 = alloc_ref $C
  %2 = alloc_ref $C
  cond_br undef, bb1, bb2

bb1:
  br bb3(%1 : $C)

bb2:
  br bb3(%2 : $C)

bb3(%3 : $C):
  strong_release %3 : $C
  %4 = tuple()
  return %4 : $()
}

// Make sure retain instruction is sunk across copy_addr inst, as copy_addr
// dest is initialized.
//
// CHECK-LABEL: retain_not_blocked_by_copyaddrinit
// CHECK: bb0
// CHECK-NEXT: strong_release
// CHECK-NEXT: copy_addr
// CHECK-NEXT: tuple
// CHECK-NEXT: strong_retain
sil hidden @retain_not_blocked_by_copyaddrinit : $@convention(thin) <T> (@in T, B) -> @out T {
bb0(%0 : $*T, %1 : $*T, %2 : $B):
  strong_release %2 : $B
  strong_retain %2 : $B
  copy_addr [take] %1 to [initialization] %0 : $*T // id: %3
  %4 = tuple ()                                   // user: %5
  return %4 : $()                                 // id: %5
}

// Make sure that is_unique stops code motion.
// CHECK-LABEL: sil @is_unique_stops_codemotion : $@convention(thin) (@inout Builtin.NativeObject) -> () {
// CHECK: bb0([[IN:%[0-9]+]] : $*Builtin.NativeObject):
// CHECK: [[LD:%[0-9]+]] = load [[IN]] : $*Builtin.NativeObject
// CHECK: strong_retain [[LD]] : $Builtin.NativeObject
// CHECK: is_unique [[IN]] : $*Builtin.NativeObject
sil @is_unique_stops_codemotion : $@convention(thin) (@inout Builtin.NativeObject) -> () {
bb0(%0 : $*Builtin.NativeObject):
  %1 = load %0 : $*Builtin.NativeObject
  strong_retain %1 : $Builtin.NativeObject
  is_unique %0 : $*Builtin.NativeObject
  %9999 = tuple()
  return %9999 : $()
}

// Make sure that is_unique stops code motion.
// CHECK-LABEL: sil @retain_inserted_deterministically : $@convention(thin)
// CHECK: bb0([[IN0:%[0-9]+]] : $Builtin.NativeObject, [[IN1:%[0-9]+]] : $Builtin.NativeObject, [[IN2:%[0-9]+]] : $Builtin.NativeObject, [[IN3:%[0-9]+]] : $Builtin.NativeObject):
// CHECK: strong_retain [[IN1]] : $Builtin.NativeObject
// CHECK: strong_retain [[IN3]] : $Builtin.NativeObject
// CHECK: strong_retain [[IN2]] : $Builtin.NativeObject
// CHECK: strong_retain [[IN0]] : $Builtin.NativeObject
sil @retain_inserted_deterministically : $@convention(thin) (@owned Builtin.NativeObject, @owned Builtin.NativeObject, @owned Builtin.NativeObject, @owned Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject, %1 : $Builtin.NativeObject, %2 : $Builtin.NativeObject, %3 : $Builtin.NativeObject):
  strong_retain %1 : $Builtin.NativeObject
  strong_retain %3 : $Builtin.NativeObject
  strong_retain %2 : $Builtin.NativeObject
  strong_retain %0 : $Builtin.NativeObject
  %9999 = tuple()
  %9998 = function_ref @blocker : $@convention(thin) () -> ()
  apply %9998() : $@convention(thin) () -> ()
  return %9999 : $()
}

// CHECK-LABEL: sil @sink_retain_partially_block : $@convention(thin) (Builtin.NativeObject) -> () {
// CHECK: bb3:
// CHECK-NOT: string_retain
// CHECK: return
sil @sink_retain_partially_block : $@convention(thin) (Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject):
  strong_retain %0 : $Builtin.NativeObject
  cond_br undef, bb1, bb2

bb1:
  %2 = function_ref @blocker : $@convention(thin) () -> ()
  apply %2() : $@convention(thin) () -> ()
  br bb3

bb2:
  br bb3

bb3:
  %5 = tuple()
  return %5 : $()
}

final class MyArrayBuffer {
  @_hasStorage var dummyElements: Int32
  init()
}

// CHECK-LABEL: sil @builtin_does_not_block_locally_allocated_ref
// CHECK: builtin
// CHECK-NEXT: return
sil @builtin_does_not_block_locally_allocated_ref : $@convention(thin) () -> @owned MyArrayBuffer {
bb0:
  %3 = integer_literal $Builtin.Word, 3
  %8 = alloc_ref $MyArrayBuffer
  %74 = metatype $@thick String.Type
  %67 = ref_element_addr %8 : $MyArrayBuffer, #MyArrayBuffer.dummyElements
  %68 = address_to_pointer %67 : $*Int32 to $Builtin.RawPointer
  strong_retain %8 : $MyArrayBuffer
  %77 = builtin "destroyArray"<String>(%74 : $@thick String.Type, %68 : $Builtin.RawPointer, %3 : $Builtin.Word) : $()
  strong_release %8 : $MyArrayBuffer
  return %8 : $MyArrayBuffer
}
// CHECK-LABEL: sil @hoist_release_partially_available_retain
// CHECK: bb0
// CHECK: cond_br undef, bb1, bb2
// CHECK: bb1:
// CHECK-NEXT: br bb3
// CHECK: bb2:
// CHECK: strong_retain
// CHECK: apply
// CHECK: strong_release
// CHECK: br bb3
// CHECK: bb3:
// CHECK-NOT: strong_release
// CHECK: return
sil @hoist_release_partially_available_retain : $@convention(thin) (Builtin.NativeObject, Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject, %1: $Builtin.NativeObject):
  cond_br undef, bb1, bb2

bb1:
  strong_retain %0: $Builtin.NativeObject
  br bb3

bb2:
  strong_retain %0: $Builtin.NativeObject
  %2 = function_ref @blocker : $@convention(thin) () -> ()
  apply %2() : $@convention(thin) () -> ()
  br bb3

bb3:
  strong_release %0: $Builtin.NativeObject
  %5 = tuple()
  return %5 : $()
}

// CHECK-LABEL: sil [serialized] @try_apply_blocks_release_hoisting : $@convention(thin) (Builtin.NativeObject) -> @error Error {
// CHECK: bb0(
// CHECK: strong_retain
// CHECK: try_apply
// CHECK: bb1(
// CHECK: strong_release
// CHECK: bb2(
// CHECK: strong_release
sil [serialized] @try_apply_blocks_release_hoisting : $@convention(thin) (Builtin.NativeObject) -> @error Error {
bb0(%0 : $Builtin.NativeObject):
  strong_retain %0 : $Builtin.NativeObject
  %1 = function_ref @guaranteed_use : $@convention(thin) (@guaranteed Builtin.NativeObject) -> ()
  apply %1(%0) : $@convention(thin) (@guaranteed Builtin.NativeObject) -> ()
  %2 = function_ref @guaranteed_throwing_use : $@convention(thin) (@guaranteed Builtin.NativeObject) -> @error Error
  try_apply %2(%0) : $@convention(thin) (@guaranteed Builtin.NativeObject) -> @error Error, normal bb1, error bb2

bb1(%3 : $()):
  strong_release %0 : $Builtin.NativeObject
  return undef : $()

bb2(%4 : $Error):
  strong_release %0 : $Builtin.NativeObject
  throw %4 : $Error
}


// Make sure release can be hoisted across memory that do not escape.
// CHECK-LABEL: sil @hoist_release_across_local_memory_use
// CHECK: bb1:
// CHECK-NEXT: br bb3
// CHECK: bb2:
// CHECK: strong_release
// CHECK: br bb3
// CHECK: bb3:
// CHECK-NOT: strong_release
// CHECK: return
sil @hoist_release_across_local_memory_use : $@convention(thin) (Builtin.NativeObject) ->() {
bb0(%0 : $Builtin.NativeObject):
  %1 = alloc_stack $A
  cond_br undef, bb1, bb2

bb1:
  strong_retain %0 : $Builtin.NativeObject
  br bb3

bb2:
  br bb3

bb3:
  %2 = integer_literal $Builtin.Int32, 0
  %3 = struct $A (%2 : $Builtin.Int32)
  store %3 to %1 : $*A
  strong_release %0 : $Builtin.NativeObject
  dealloc_stack %1 : $*A
  %5 = tuple()
  return %5 : $()
}

// Make sure release can not be hoisted across memory that do escape. i.e. the release
// deinit can read or write to the memory.
// CHECK-LABEL: sil @hoist_release_across_escaping_param_memory_use
// CHECK: bb1:
// CHECK-NOT: strong_release
// CHECK: br bb3
// CHECK: bb2:
// CHECK-NOT: strong_release
// CHECK: br bb3
// CHECK: bb3:
// CHECK: store
// CHECK: strong_release
// CHECK: return
sil @hoist_release_across_escaping_param_memory_use : $@convention(thin) (Builtin.NativeObject, C2) ->() {
bb0(%0 : $Builtin.NativeObject, %1 : $C2):
  %2 = ref_element_addr %1 : $C2, #C2.current
  cond_br undef, bb1, bb2

bb1:
  strong_retain %0 : $Builtin.NativeObject
  br bb3

bb2:
  br bb3

bb3:
  %3 = integer_literal $Builtin.Int32, 0
  %4 = struct $A (%3 : $Builtin.Int32)
  store %4 to %2 : $*A
  strong_release %0 : $Builtin.NativeObject
  %5 = tuple()
  return %5 : $()
}

// Make sure release can not be hoisted across memory that do escape, even though its allocated locally.
// i.e. the release
// deinit can read or write to the memory.
// CHECK-LABEL: sil @hoist_release_across_escaping_local_alloc_memory_use
// CHECK: bb1:
// CHECK-NOT: strong_release
// CHECK: br bb3
// CHECK: bb2:
// CHECK-NOT: strong_release
// CHECK: br bb3
// CHECK: bb3:
// CHECK: store
// CHECK: strong_release
// CHECK: return
sil @hoist_release_across_escaping_local_alloc_memory_use : $@convention(thin) (Builtin.NativeObject) ->() {
bb0(%0 : $Builtin.NativeObject):
  %1 = alloc_ref $C2
  %2 = ref_element_addr %1 : $C2, #C2.current
  cond_br undef, bb1, bb2

bb1:
  strong_retain %0 : $Builtin.NativeObject
  br bb3

bb2:
  br bb3

bb3:
  %22 = function_ref @use_C2 : $@convention(thin) (C2) -> ()
  %23 = apply %22(%1) : $@convention(thin) (C2) -> ()
  %3 = integer_literal $Builtin.Int32, 0
  %4 = struct $A (%3 : $Builtin.Int32)
  store %4 to %2 : $*A
  strong_release %0 : $Builtin.NativeObject
  %5 = tuple()
  return %5 : $()
}

// CHECK-LABEL: sil @move_retain_over_loop
// CHECK:      bb0({{.*}}):
// CHECK-NEXT:   br bb1
// CHECK:      bb1:
// CHECK-NEXT:   cond_br
// CHECK:      bb2:
// CHECK:        strong_retain
// CHECK:        apply
// CHECK:        strong_release
// CHECK:        return
sil @move_retain_over_loop : $@convention(thin) (Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject):
  strong_retain %0 : $Builtin.NativeObject
  br bb1

bb1:
  cond_br undef, bb1, bb2

bb2:
  %2 = function_ref @blocker : $@convention(thin) () -> ()
  apply %2() : $@convention(thin) () -> ()
  strong_release %0 : $Builtin.NativeObject
  %1 = tuple()
  return %1 : $()
}

// CHECK-LABEL: sil @move_release_over_loop
// CHECK:      bb0{{.*}}:
// CHECK:        strong_retain
// CHECK:        apply
// CHECK:        strong_release
// CHECK:        br bb1
// CHECK:      bb1:
// CHECK-NEXT:   cond_br
// CHECK:      bb2:
// CHECK-NEXT:   br bb1
// CHECK:      bb3:
// CHECK-NEXT:   tuple
// CHECK-NEXT:   return
sil @move_release_over_loop : $@convention(thin) (Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject):
  strong_retain %0 : $Builtin.NativeObject
  %2 = function_ref @blocker : $@convention(thin) () -> ()
  apply %2() : $@convention(thin) () -> ()
  br bb1

bb1:
  cond_br undef, bb1, bb2

bb2:
  strong_release %0 : $Builtin.NativeObject
  %1 = tuple()
  return %1 : $()
}

// CHECK-LABEL: sil @handle_infinite_loop
// CHECK:      bb0{{.*}}:
// CHECK-NEXT:   cond_br
// CHECK:      bb1:
// CHECK-NOT:    {{(retain|release)}}
// CHECK:        apply
// CHECK-NEXT:   br bb2
// CHECK:      bb2:
// CHECK-NEXT:   br bb2
// CHECK:      bb3:
// CHECK-NEXT:   tuple
// CHECK-NEXT:   return
sil @handle_infinite_loop : $@convention(thin) (@inout Builtin.NativeObject) -> () {
bb0(%a : $*Builtin.NativeObject):
  cond_br undef, bb1, bb3

bb1:
  %2 = function_ref @blocker : $@convention(thin) () -> ()
  apply %2() : $@convention(thin) () -> ()
  br bb2

bb2:
  br bb2

bb3:
  %0 = load %a : $*Builtin.NativeObject
  strong_retain %0 : $Builtin.NativeObject
  strong_release %0 : $Builtin.NativeObject
  %1 = tuple()
  return %1 : $()
}

/// Check that retain sinking needs multiple-passes to sink 2 retains.

/// One round of retain-sinking can sink only one of retains.
/// CHECK-LABEL: sil @checkRetainSinkingMultipleRounds
/// CHECK:      bb9:
/// CHECK-NEXT:   release_value %2 : $S
/// In the ideal world, we should see a third retain_value here.
/// But it would require another round of retain sinking.
/// CHECK-NEXT:   br bb5


/// Two rounds of retain-sinking can sink only two retains.
/// CHECK-MULTIPLE-RS-ROUNDS-LABEL: sil @checkRetainSinkingMultipleRounds
/// CHECK-MULTIPLE-RS-ROUNDS:      bb9:
/// CHECK-MULTIPLE-RS-ROUNDS-NEXT:   retain_value %2 : $S
/// CHECK-MULTIPLE-RS-ROUNDS-NEXT:   release_value %2 : $S
/// CHECK-MULTIPLE-RS-ROUNDS-NEXT:   br bb5

sil @checkRetainSinkingMultipleRounds : $@convention(thin) (Int) -> () {
bb0(%0 : $Int):
  %1 = function_ref @createS : $@convention(thin) () -> @owned S
  %2 = apply %1() : $@convention(thin) () -> @owned S
  br bb2

bb1: 
  cond_br undef, bb10, bb11 

bb2: 
  cond_br undef, bb4, bb6

bb3:
  br bb2

bb4:
  retain_value %2 : $S
  br bb5

bb5:
  release_value %2 : $S
  cond_br undef, bb1, bb3

bb6:
  retain_value %2 : $S
  retain_value %2 : $S
  br bb7

bb7:
  cond_br undef, bb9, bb8

bb8:
  br bb7

bb9:
  release_value %2 : $S
  br bb5

bb10:
  unreachable

bb11:
  release_value %2 : $S
  %26 = tuple ()
  return %26 : $()
}

// CHECK-LABEL: sil @detect_escape_of_bbarg
// CHECK:      bb3({{.*}}):
// CHECK-NEXT:   strong_retain
// CHECK-NEXT:   apply
// CHECK-NEXT:   strong_release
sil @detect_escape_of_bbarg : $@convention(thin) () -> () {
bb0:
  %f = function_ref @use_C2 : $@convention(thin) (C2) -> ()
  cond_br undef, bb1, bb2

bb1:
  %a = alloc_ref $C2
  br bb3(%a: $C2, %a: $C2)

bb2:
  %b = alloc_ref $C2
  br bb3(%b: $C2, %b: $C2)

bb3(%p1: $C2, %p2: $C2):
  strong_retain %p1: $C2 // This retain must not be moved over the apply
  %c = apply %f(%p2) : $@convention(thin) (C2) -> ()
  strong_release %p2: $C2
  %10 = tuple ()
  return %10 : $()
}

// CHECK-LABEL: sil @test_unowned
// CHECK:      bb0(%0 : $Builtin.NativeObject):
// CHECK-NEXT:   br bb1    
// CHECK:      bb1:
// CHECK-NEXT:   tuple
// CHECK-NEXT:   return
sil @test_unowned : $@convention(thin) (@guaranteed Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject):
  %1 = ref_to_unowned %0 : $Builtin.NativeObject to $@sil_unowned Builtin.NativeObject
  %2 = struct $Unowned (%1 : $@sil_unowned Builtin.NativeObject)
  retain_value %2: $Unowned
  br bb1

bb1:
  release_value %2: $Unowned
  %5 = tuple()
  return %5 : $()
}

// CHECK-RELEASE-HOISTING-LABEL: sil @dont_eliminate_strong_retain_and_unowned_release_pair
// CHECK-RELEASE-HOISTING:       = function_ref @blocker
// CHECK-RELEASE-HOISTING-NEXT:  apply
// CHECK-RELEASE-HOISTING-NEXT:  strong_retain %0 : $Builtin.NativeObject
// CHECK-RELEASE-HOISTING-NEXT:  unowned_release %1 : $@sil_unowned Builtin.NativeObject
sil @dont_eliminate_strong_retain_and_unowned_release_pair : $@convention(thin) (@guaranteed Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject):
  %1 = ref_to_unowned %0 : $Builtin.NativeObject to $@sil_unowned Builtin.NativeObject
  %2 = struct $Unowned (%1 : $@sil_unowned Builtin.NativeObject)
  retain_value %2: $Unowned
  %b = function_ref @blocker : $@convention(thin) () -> ()
  apply %b() : $@convention(thin) () -> ()
  strong_retain %0: $Builtin.NativeObject
  br bb1

bb1:
  release_value %2: $Unowned
  apply %b() : $@convention(thin) () -> ()
  strong_release %0: $Builtin.NativeObject
  %5 = tuple()
  return %5 : $()
}

sil [_semantics "programtermination_point"] @fatalError : $@convention(thin) () -> Never

// This should eliminate all retains except for the first one b/c of user.
// CHECK-LABEL: sil @eliminate_retains_on_fatalError_path_single_bb : $@convention(thin) (@owned Builtin.NativeObject) -> () {
// CHECK: strong_retain
// CHECK-NOT: strong_retain
// CHECK: } // end sil function 'eliminate_retains_on_fatalError_path_single_bb'
sil @eliminate_retains_on_fatalError_path_single_bb : $@convention(thin) (@owned Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject):
  strong_retain %0 : $Builtin.NativeObject
  %2 = function_ref @user : $@convention(thin) (Builtin.NativeObject) -> ()
  apply %2(%0) : $@convention(thin) (Builtin.NativeObject) -> ()
  strong_retain %0 : $Builtin.NativeObject
  %1 = function_ref @fatalError : $@convention(thin) () -> Never
  strong_retain %0 : $Builtin.NativeObject
  apply %1() : $@convention(thin) () -> Never
  unreachable
}

// We should eliminate all retains except for the one that we sink into the
// return block.
//
// CHECK-LABEL: sil @eliminate_retains_on_fatalError_path_diamond : $@convention(thin) (@owned Builtin.NativeObject) -> () {
// CHECK-NOT: strong_retain
// CHECK: bb4:
// CHECK: strong_retain
// CHECK-NOT: strong_retain
// CHECK: } // end sil function 'eliminate_retains_on_fatalError_path_diamond'
sil @eliminate_retains_on_fatalError_path_diamond : $@convention(thin) (@owned Builtin.NativeObject) -> () {
bb0(%0 : $Builtin.NativeObject):
  strong_retain %0 : $Builtin.NativeObject
  cond_br undef, bb1, bb2

bb1:
  cond_br undef, bb3, bb4

bb3:
  strong_retain %0 : $Builtin.NativeObject
  %1 = function_ref @fatalError : $@convention(thin) () -> Never
  strong_retain %0 : $Builtin.NativeObject
  apply %1() : $@convention(thin) () -> Never
  unreachable

bb4:
  unreachable

bb2:
  %9999 = tuple()
  return %9999 : $()
}