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Optimizer: add simplification for switch_enum
Replace ``` %1 = enum $E, #someCase, %payload switch_enum %1, case #someCase: bb1, ... bb1(%payloadArgument): ``` -> ``` br bb1(%payload) bb1(%payloadArgument): ```
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‎SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/CMakeLists.txt

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@@ -28,6 +28,7 @@ swift_compiler_sources(Optimizer
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SimplifyRetainReleaseValue.swift
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SimplifyStrongRetainRelease.swift
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SimplifyStructExtract.swift
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SimplifySwitchEnum.swift
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SimplifyTupleExtract.swift
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SimplifyUncheckedEnumData.swift
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SimplifyValueToBridgeObject.swift)

‎SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifySwitchEnum.swift

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//===--- SimplifySwitchEnum.swift -----------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import SIL
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// Removes an `enum` - `switch_enum` pair:
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// ```
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// %1 = enum $E, #someCase, %payload
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// switch_enum %1, case #someCase: bb1, ...
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// bb1(%payloadArgument):
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// ```
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// ->
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// ```
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// br bb1(%payload)
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// bb1(%payloadArgument):
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// ```
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//
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// Other case blocks of the switch_enum become dead.
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//
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extension SwitchEnumInst : OnoneSimplifyable {
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func simplify(_ context: SimplifyContext) {
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guard let enumInst = enumOp as? EnumInst,
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let caseBlock = getUniqueSuccessor(forCaseIndex: enumInst.caseIndex) else
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{
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return
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}
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let singleUse = context.preserveDebugInfo ? enumInst.uses.singleUse : enumInst.uses.ignoreDebugUses.singleUse
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let canEraseEnumInst = singleUse?.instruction == self
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if !canEraseEnumInst && parentFunction.hasOwnership && enumInst.ownership == .owned {
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// We cannot add more uses to the `enum` instruction without inserting a copy.
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return
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}
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let builder = Builder(before: self, context)
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switch caseBlock.arguments.count {
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case 0:
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precondition(enumInst.payload == nil || !parentFunction.hasOwnership,
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"missing payload argument in switch_enum case block")
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builder.createBranch(to: caseBlock)
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case 1:
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builder.createBranch(to: caseBlock, arguments: [enumInst.payload!])
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default:
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fatalError("case block of switch_enum cannot have more than 1 argument")
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}
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context.erase(instruction: self)
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if canEraseEnumInst {
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context.erase(instructionIncludingDebugUses: enumInst)
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}
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}
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}

‎test/SILOptimizer/simplify_unchecked_switch_enum.sil

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// RUN: %target-sil-opt -enable-sil-verify-all %s -onone-simplification -simplify-instruction=switch_enum | %FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-ONONE
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// RUN: %target-sil-opt -enable-sil-verify-all %s -simplification -simplify-instruction=switch_enum | %FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-O
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// REQUIRES: swift_in_compiler
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import Swift
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import Builtin
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enum E {
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case A
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case B(String)
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case C(Int)
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}
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// CHECK-LABEL: sil @test_simple :
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// CHECK: bb0(%0 : $String):
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// CHECK-NEXT: br bb1(%0 : $String)
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// CHECK: bb1(%2 : $String):
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// CHECK-NEXT: return %2 : $String
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// CHECK-NOT: bb2
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// CHECK: } // end sil function 'test_simple'
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sil @test_simple : $@convention(thin) (@owned String) -> @owned String {
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bb0(%0 : $String):
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%1 = enum $E, #E.B!enumelt, %0 : $String
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switch_enum %1 : $E, case #E.B!enumelt: bb1, default bb2
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bb1(%2 : $String):
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return %2 : $String
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bb2:
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unreachable
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}
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// CHECK-LABEL: sil @no_payload_argument :
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// CHECK: bb0(%0 : $String):
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// CHECK-NEXT: br bb1
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// CHECK: bb1:
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// CHECK-NEXT: tuple
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// CHECK-NEXT: return
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// CHECK-NOT: bb2
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// CHECK: } // end sil function 'no_payload_argument'
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sil @no_payload_argument : $@convention(thin) (@guaranteed String) -> () {
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bb0(%0 : $String):
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%1 = enum $E, #E.B!enumelt, %0 : $String
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switch_enum %1 : $E, case #E.B!enumelt: bb1, default bb2
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bb1:
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%2 = tuple ()
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return %2 : $()
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bb2:
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unreachable
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}
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// CHECK-LABEL: sil [ossa] @owned_ossa :
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// CHECK: bb0(%0 : @owned $String):
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// CHECK-NEXT: br bb1(%0 : $String)
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// CHECK: bb1(%2 : @owned $String):
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// CHECK-NEXT: return %2 : $String
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// CHECK-NOT: bb2
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// CHECK: } // end sil function 'owned_ossa'
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sil [ossa] @owned_ossa : $@convention(thin) (@owned String) -> @owned String {
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bb0(%0 : @owned $String):
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%1 = enum $E, #E.B!enumelt, %0 : $String
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switch_enum %1 : $E, case #E.B!enumelt: bb1, default bb2
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bb1(%2 : @owned $String):
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return %2 : $String
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bb2(%4 : @owned $E):
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unreachable
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}
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// CHECK-LABEL: sil [ossa] @guaranteed_ossa :
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// CHECK: bb0(%0 : @guaranteed $String):
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// CHECK-NEXT: br bb1(%0 : $String)
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// CHECK: bb1(%2 : @guaranteed $String):
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// CHECK-NEXT: %3 = copy_value %2
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// CHECK-NEXT: return %3 : $String
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// CHECK-NOT: bb2
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// CHECK: } // end sil function 'guaranteed_ossa'
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sil [ossa] @guaranteed_ossa : $@convention(thin) (@guaranteed String) -> @owned String {
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bb0(%0 : @guaranteed $String):
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%1 = enum $E, #E.B!enumelt, %0 : $String
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switch_enum %1 : $E, case #E.B!enumelt: bb1, default bb2
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bb1(%2 : @guaranteed $String):
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%3 = copy_value %2 : $String
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return %3 : $String
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bb2(%4 : @guaranteed $E):
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unreachable
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}
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// CHECK-LABEL: sil [ossa] @owned_with_additional_uses :
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// CHECK: switch_enum
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// CHECK: } // end sil function 'owned_with_additional_uses'
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sil [ossa] @owned_with_additional_uses : $@convention(thin) (@owned String) -> @owned String {
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bb0(%0 : @owned $String):
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%1 = enum $E, #E.B!enumelt, %0 : $String
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%2 = begin_borrow %1 : $E
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end_borrow %2 : $E
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switch_enum %1 : $E, case #E.B!enumelt: bb1, default bb2
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bb1(%5 : @owned $String):
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return %5 : $String
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bb2(%7 : @owned $E):
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unreachable
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}
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// CHECK-LABEL: sil [ossa] @guaranteed_with_additional_uses :
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// CHECK: enum
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// CHECK-NEXT: begin_borrow
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// CHECK-NEXT: end_borrow
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// CHECK-NEXT: br bb1(%0 : $String)
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// CHECK: bb1([[A:%.*]] : @guaranteed $String):
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// CHECK-NEXT: [[C:%.*]] = copy_value [[A]]
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// CHECK-NEXT: return [[C]] : $String
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// CHECK-NOT: bb2
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// CHECK: } // end sil function 'guaranteed_with_additional_uses'
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sil [ossa] @guaranteed_with_additional_uses : $@convention(thin) (@guaranteed String) -> @owned String {
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bb0(%0 : @guaranteed $String):
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%1 = enum $E, #E.B!enumelt, %0 : $String
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%2 = begin_borrow %1 : $E
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end_borrow %2 : $E
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switch_enum %1 : $E, case #E.B!enumelt: bb1, default bb2
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bb1(%5 : @guaranteed $String):
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%6 = copy_value %5 : $String
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return %6 : $String
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bb2(%7 : @guaranteed $E):
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unreachable
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}
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// CHECK-LABEL: sil [ossa] @owned_with_debug_uses :
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// CHECK: bb0(%0 : @owned $String):
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// CHECK-O: br bb1(%0 : $String)
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// CHECK-ONONE: switch_enum
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// CHECK: } // end sil function 'owned_with_debug_uses'
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sil [ossa] @owned_with_debug_uses : $@convention(thin) (@owned String) -> @owned String {
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bb0(%0 : @owned $String):
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%1 = enum $E, #E.B!enumelt, %0 : $String
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debug_value %1 : $E, let, name "e"
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switch_enum %1 : $E, case #E.B!enumelt: bb1, default bb2
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bb1(%2 : @owned $String):
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return %2 : $String
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bb2(%4 : @owned $E):
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unreachable
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}
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