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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
35 lines
1.3 KiB
Swift
35 lines
1.3 KiB
Swift
// RUN: %target-swift-frontend -module-name moveonly_class_inits_end_to_end %s -emit-sil -o - | %FileCheck %s
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// RUN: %target-swift-frontend %s -O -emit-sil -sil-verify-all > /dev/null
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// A test that makes sure end to end in a copyable class containing a
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// non-copyable type, in the init, we only have a single destroy_addr.
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// REQUIRES: swift_in_compiler
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public struct MO: ~Copyable {
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var x: Int8 = 0
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deinit { print("destroyed MO") }
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}
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public class MOHaver {
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var mo: MO
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// CHECK-LABEL: sil hidden @$s028moveonly_class_inits_end_to_D07MOHaverCACycfc : $@convention(method) (@owned MOHaver) -> @owned MOHaver {
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// CHECK: bb0([[ARG:%.*]] :
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// CHECK-NEXT: debug_value [[ARG]]
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// CHECK-NEXT: [[EI:%.*]] = end_init_let_ref [[ARG]]
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// CHECK-NEXT: [[META:%.*]] = metatype
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// CHECK-NEXT: function_ref MO.init()
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// CHECK-NEXT: [[FUNC:%.*]] = function_ref @$s028moveonly_class_inits_end_to_D02MOVACycfC :
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// CHECK-NEXT: [[RESULT:%.*]] = apply [[FUNC]]([[META]])
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// CHECK-NEXT: [[REF:%.*]] = ref_element_addr [[EI]]
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// CHECK-NEXT: [[REF_ACCESS:%.*]] = begin_access [modify] [dynamic] [[REF]]
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// CHECK-NEXT: store [[RESULT]] to [[REF_ACCESS]]
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// CHECK-NEXT: end_access [[REF_ACCESS]]
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// CHECK-NEXT: return [[EI]]
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// CHECK-NEXT: } // end sil function '$s028moveonly_class_inits_end_to_D07MOHaverCACycfc'
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init() {
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self.mo = MO()
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}
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}
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