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Swift Optimizer: add simplifications for destructure_struct and destructure_tuple
Eliminate the redundant instruction pair ``` %t = tuple (%0, %1, %2) (%3, %4, %5) = destructure_tuple %t ``` and replace the results %3, %4, %5 with %0, %1, %2, respectively. The same for structs.
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‎SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/CMakeLists.txt

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@@ -14,6 +14,7 @@ swift_compiler_sources(Optimizer
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SimplifyCondBranch.swift
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SimplifyCondFail.swift
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SimplifyDebugStep.swift
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SimplifyDestructure.swift
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SimplifyGlobalValue.swift
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SimplifyStrongRetainRelease.swift
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SimplifyStructExtract.swift

‎SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyDestructure.swift

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//===--- SimplifyDestructure.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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extension DestructureTupleInst : OnoneSimplifyable {
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func simplify(_ context: SimplifyContext) {
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// Eliminate the redundant instruction pair
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// ```
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// %t = tuple (%0, %1, %2)
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// (%3, %4, %5) = destructure_tuple %t
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// ```
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// and replace the results %3, %4, %5 with %0, %1, %2, respectively
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//
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if let tuple = self.tuple as? TupleInst {
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tryReplaceConstructDestructPair(construct: tuple, destruct: self, context)
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}
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}
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}
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extension DestructureStructInst : OnoneSimplifyable {
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func simplify(_ context: SimplifyContext) {
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// Eliminate the redundant instruction pair
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// ```
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// %s = struct (%0, %1, %2)
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// (%3, %4, %5) = destructure_struct %s
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// ```
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// and replace the results %3, %4, %5 with %0, %1, %2, respectively
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//
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if let str = self.struct as? StructInst {
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tryReplaceConstructDestructPair(construct: str, destruct: self, context)
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}
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}
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}
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private func tryReplaceConstructDestructPair(construct: SingleValueInstruction,
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destruct: MultipleValueInstruction,
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_ context: SimplifyContext) {
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let singleUse = context.preserveDebugInfo ? construct.uses.singleUse : construct.uses.singleNonDebugUse
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let canEraseFirst = singleUse?.instruction == destruct
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if !canEraseFirst && construct.parentFunction.hasOwnership && construct.ownership == .owned {
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// We cannot add more uses to this tuple without inserting a copy.
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return
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}
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for (result, operand) in zip(destruct.results, construct.operands) {
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result.uses.replaceAll(with: operand.value, context)
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}
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if canEraseFirst {
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context.erase(instructionIncludingDebugUses: destruct)
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}
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}

‎test/SILOptimizer/simplify_destructure_struct.sil

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// RUN: %target-sil-opt -enable-sil-verify-all %s -onone-simplification -simplify-instruction=destructure_struct | %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=destructure_struct | %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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struct S {
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@_hasStorage let a: String
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@_hasStorage let b: Int
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}
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// CHECK-LABEL: sil [ossa] @forward_owned :
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// CHECK-NOT: destructure_tuple
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// CHECK: fix_lifetime %1
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// CHECK: return %0
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// CHECK: } // end sil function 'forward_owned'
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sil [ossa] @forward_owned : $@convention(thin) (@owned String, Int) -> @owned String {
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bb0(%0 : @owned $String, %1 : $Int):
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%2 = struct $S (%0 : $String, %1 : $Int)
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(%3, %4) = destructure_struct %2 : $S
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fix_lifetime %4 : $Int
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return %3 : $String
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}
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// CHECK-LABEL: sil [ossa] @forward_borrowed :
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// CHECK-NOT: destructure_struct
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// CHECK: fix_lifetime %0
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// CHECK: fix_lifetime %1
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// CHECK: } // end sil function 'forward_borrowed'
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sil [ossa] @forward_borrowed : $@convention(thin) (@guaranteed String, Int) -> () {
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bb0(%0 : @guaranteed $String, %1 : $Int):
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%2 = struct $S (%0 : $String, %1 : $Int)
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(%3, %4) = destructure_struct %2 : $S
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fix_lifetime %3 : $String
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fix_lifetime %4 : $Int
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%7 = tuple ()
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return %7 : $()
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}
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// CHECK-LABEL: sil [ossa] @dont_forward_owned_with_uses :
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// CHECK: (%5, %6) = destructure_struct %2 : $S
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// CHECK: fix_lifetime %6
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// CHECK: return %5
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// CHECK: } // end sil function 'dont_forward_owned_with_uses'
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sil [ossa] @dont_forward_owned_with_uses : $@convention(thin) (@owned String, Int) -> @owned String {
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bb0(%0 : @owned $String, %1 : $Int):
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%2 = struct $S (%0 : $String, %1 : $Int)
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%3 = begin_borrow %2 : $S
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end_borrow %3 : $S
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(%5, %6) = destructure_struct %2 : $S
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fix_lifetime %6 : $Int
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return %5 : $String
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}
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// CHECK-LABEL: sil [ossa] @forward_owned_with_debug_use :
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// CHECK-ONONE: (%4, %5) = destructure_struct %2 : $S
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// CHECK-ONONE: fix_lifetime %5
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// CHECK-ONONE: return %4
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// CHECK-O: fix_lifetime %1
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// CHECK-O: return %0
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// CHECK: } // end sil function 'forward_owned_with_debug_use'
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sil [ossa] @forward_owned_with_debug_use : $@convention(thin) (@owned String, Int) -> @owned String {
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bb0(%0 : @owned $String, %1 : $Int):
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%2 = struct $S (%0 : $String, %1 : $Int)
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debug_value %2 : $S, let, name "s"
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(%4, %5) = destructure_struct %2 : $S
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fix_lifetime %5 : $Int
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return %4 : $String
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}
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‎test/SILOptimizer/simplify_destructure_tuple.sil

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// RUN: %target-sil-opt -enable-sil-verify-all %s -onone-simplification -simplify-instruction=destructure_tuple | %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=destructure_tuple | %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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// CHECK-LABEL: sil [ossa] @forward_owned :
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// CHECK-NOT: destructure_tuple
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// CHECK: fix_lifetime %1
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// CHECK: return %0
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// CHECK: } // end sil function 'forward_owned'
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sil [ossa] @forward_owned : $@convention(thin) (@owned String, Int) -> @owned String {
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bb0(%0 : @owned $String, %1 : $Int):
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%2 = tuple (%0 : $String, %1 : $Int)
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(%3, %4) = destructure_tuple %2 : $(String, Int)
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fix_lifetime %4 : $Int
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return %3 : $String
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}
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// CHECK-LABEL: sil [ossa] @forward_borrowed :
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// CHECK-NOT: destructure_tuple
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// CHECK: fix_lifetime %0
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// CHECK: fix_lifetime %1
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// CHECK: } // end sil function 'forward_borrowed'
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sil [ossa] @forward_borrowed : $@convention(thin) (@guaranteed String, Int) -> () {
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bb0(%0 : @guaranteed $String, %1 : $Int):
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%2 = tuple (%0 : $String, %1 : $Int)
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(%3, %4) = destructure_tuple %2 : $(String, Int)
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fix_lifetime %3 : $String
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fix_lifetime %4 : $Int
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%7 = tuple ()
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return %7 : $()
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}
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// CHECK-LABEL: sil [ossa] @dont_forward_owned_with_uses :
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// CHECK: (%5, %6) = destructure_tuple %2 : $(String, Int)
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// CHECK: fix_lifetime %6
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// CHECK: return %5
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// CHECK: } // end sil function 'dont_forward_owned_with_uses'
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sil [ossa] @dont_forward_owned_with_uses : $@convention(thin) (@owned String, Int) -> @owned String {
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bb0(%0 : @owned $String, %1 : $Int):
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%2 = tuple (%0 : $String, %1 : $Int)
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%3 = begin_borrow %2 : $(String, Int)
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end_borrow %3 : $(String, Int)
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(%5, %6) = destructure_tuple %2 : $(String, Int)
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fix_lifetime %6 : $Int
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return %5 : $String
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}
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// CHECK-LABEL: sil [ossa] @forward_owned_with_debug_use :
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// CHECK-ONONE: (%4, %5) = destructure_tuple %2 : $(String, Int)
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// CHECK-ONONE: fix_lifetime %5
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// CHECK-ONONE: return %4
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// CHECK-O: fix_lifetime %1
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// CHECK-O: return %0
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// CHECK: } // end sil function 'forward_owned_with_debug_use'
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sil [ossa] @forward_owned_with_debug_use : $@convention(thin) (@owned String, Int) -> @owned String {
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bb0(%0 : @owned $String, %1 : $Int):
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%2 = tuple (%0 : $String, %1 : $Int)
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debug_value %2 : $(String, Int), let, name "t"
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(%4, %5) = destructure_tuple %2 : $(String, Int)
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fix_lifetime %5 : $Int
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return %4 : $String
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}
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