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Fix copy-to-borrow optimization's end_borrow insertion #79810

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Merged
merged 1 commit into from
Mar 7, 2025
Merged

Fix copy-to-borrow optimization's end_borrow insertion #79810

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15 changes: 10 additions & 5 deletions SwiftCompilerSources/Sources/Optimizer/FunctionPasses/CopyToBorrowOptimization.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -124,10 +124,6 @@ private struct Uses {
// E.g. the none-case of a switch_enum of an Optional.
private(set) var nonDestroyingLiverangeExits: Stack<Instruction>

var allLifetimeEndingInstructions: [Instruction] {
Array(destroys.lazy.map { $0 }) + Array(nonDestroyingLiverangeExits)
}

private(set) var usersInDeadEndBlocks: Stack<Instruction>

init(_ context: FunctionPassContext) {
Expand Down Expand Up @@ -323,7 +319,16 @@ private func createEndBorrows(for beginBorrow: Value, atEndOf liverange: Instruc
// destroy_value %2
// destroy_value %3 // The final destroy. Here we need to create the `end_borrow`(s)
//
for endInst in collectedUses.allLifetimeEndingInstructions {

var allLifetimeEndingInstructions = InstructionWorklist(context)
allLifetimeEndingInstructions.pushIfNotVisited(contentsOf: collectedUses.destroys.lazy.map { $0 })
allLifetimeEndingInstructions.pushIfNotVisited(contentsOf: collectedUses.nonDestroyingLiverangeExits)

defer {
allLifetimeEndingInstructions.deinitialize()
}

while let endInst = allLifetimeEndingInstructions.pop() {
if !liverange.contains(endInst) {
let builder = Builder(before: endInst, context)
builder.createEndBorrow(of: beginBorrow)
Expand Down
46 changes: 46 additions & 0 deletions test/SILOptimizer/copy-to-borrow-optimization.sil
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Original file line number Diff line number Diff line change
Expand Up @@ -2156,3 +2156,49 @@ bb0(%0 : $*MultiPayload):
return %2
}

// CHECK-LABEL: sil [ossa] @duplicate_lifetime_end1 :
// CHECK: load_borrow %0
// CHECK: } // end sil function 'duplicate_lifetime_end1'
sil [ossa] @duplicate_lifetime_end1 : $@convention(thin) (@in_guaranteed (C, Optional<C>)) -> () {
bb0(%0 : $*(C, Optional<C>)):
%1 = load [copy] %0
(%2, %3) = destructure_tuple %1
switch_enum %3, case #Optional.some!enumelt: bb1, case #Optional.none!enumelt: bb2

bb1(%4 : @owned $C):
destroy_value %2
destroy_value %4
br bb3

bb2:
debug_value %2
destroy_value %2
br bb3

bb3:
%r = tuple ()
return %r
}

// CHECK-LABEL: sil [ossa] @duplicate_lifetime_end2 :
// CHECK: load_borrow %0
// CHECK: } // end sil function 'duplicate_lifetime_end2'
sil [ossa] @duplicate_lifetime_end2 : $@convention(thin) (@in_guaranteed (C, Optional<C>)) -> () {
bb0(%0 : $*(C, Optional<C>)):
%1 = load [copy] %0
(%2, %3) = destructure_tuple %1
switch_enum %3, case #Optional.some!enumelt: bb1, case #Optional.none!enumelt: bb2

bb1(%4 : @owned $C):
destroy_value %2
destroy_value %4
br bb3

bb2:
destroy_value %2
br bb3

bb3:
%r = tuple ()
return %r
}