mirror of
https://github.com/apple/swift.git
synced 2025-12-14 20:36:38 +01:00
5bc036661c
It lowers let property accesses of classes.
Lowering consists of two tasks:
* In class initializers, insert `end_init_let_ref` instructions at places where all let-fields are initialized.
This strictly separates the life-range of the class into a region where let fields are still written during
initialization and a region where let fields are truly immutable.
* Add the `[immutable]` flag to all `ref_element_addr` instructions (for let-fields) which are in the "immutable"
region. This includes the region after an inserted `end_init_let_ref` in an class initializer, but also all
let-field accesses in other functions than the initializer and the destructor.
This pass should run after DefiniteInitialization but before RawSILInstLowering (because it relies on `mark_uninitialized` still present in the class initializer).
Note that it's not mandatory to run this pass. If it doesn't run, SIL is still correct.
Simplified example (after lowering):
bb0(%0 : @owned C): // = self of the class initializer
%1 = mark_uninitialized %0
%2 = ref_element_addr %1, #C.l // a let-field
store %init_value to %2
%3 = end_init_let_ref %1 // inserted by lowering
%4 = ref_element_addr [immutable] %3, #C.l // set to immutable by lowering
%5 = load %4
29 lines
847 B
Swift
29 lines
847 B
Swift
// RUN: %target-swift-frontend -emit-sil -enable-lexical-lifetimes=false -O -module-name=main %s | %FileCheck %s
|
|
|
|
// REQUIRES: swift_in_compiler
|
|
|
|
class C {}
|
|
|
|
@_silgen_name("borrow")
|
|
func borrow(_ c: __shared C)
|
|
|
|
@_silgen_name("barrier")
|
|
func barrier()
|
|
|
|
// CHECK-LABEL: sil {{.*}} [lexical_lifetimes] @funky : {{.*}} {
|
|
// CHECK: [[INSTANCE:%[^,]+]] = alloc_ref $C
|
|
// CHECK: [[EI:%.*]] = end_init_let_ref [[INSTANCE]]
|
|
// CHECK: [[BORROW:%[^,]+]] = function_ref @borrow
|
|
// CHECK: apply [[BORROW]]([[EI]])
|
|
// CHECK: [[BARRIER:%[^,]+]] = function_ref @barrier
|
|
// CHECK: apply [[BARRIER]]()
|
|
// CHECK: strong_release [[EI]]
|
|
// CHECK-LABEL: } // end sil function 'funky'
|
|
@_silgen_name("funky")
|
|
@_lexicalLifetimes
|
|
func funky() {
|
|
let c = C()
|
|
borrow(c)
|
|
barrier()
|
|
}
|