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Refactor swift::findPointerEscape and handle additional cases #66723

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Merged
merged 4 commits into from
Jun 22, 2023
Merged

Refactor swift::findPointerEscape and handle additional cases #66723

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76a8f0c
Remove old hack in transitive address use walker for store_borrow
meg-gupta Jun 8, 2023
031255c
Rename hasPointerEscape -> findPointerEscape
meg-gupta May 23, 2023
4862ecc
Consolidate swift::findPointerEscape(SILValue) and swift::findPointer…
meg-gupta May 23, 2023
6d3b4e0
Handle borrow uses and interior pointer uses in swift::findPointerEscape
meg-gupta May 23, 2023
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10 changes: 0 additions & 10 deletions lib/SIL/Utils/AddressWalker.cpp
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Expand Up @@ -25,16 +25,6 @@ AddressUseKind TransitiveAddressWalker::walk(SILValue projectedAddress) && {
// When we exit, set the result to be invalidated so we can't use this again.
SWIFT_DEFER { didInvalidate = true; };

// If the projectedAddress is dead, it is itself a leaf use. Since we don't
// have an operand for it, simply bail. Dead projectedAddress is unexpected.
//
// TODO: store_borrow is currently an InteriorPointer with no uses, so we end
// up bailing. It should be in a dependence scope instead. It's not clear why
// it produces an address at all.
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We can remove the TODO comment now, but shouldn't we still report a dead projection as either a PointerEscape or Unknown? Otherwise, clients will need to separately look for and handle any possible dead projections. I don't think clients can currently handle that. Dead projections are unexpected but still legal SIL.

if (projectedAddress->use_empty()) {
return AddressUseKind::PointerEscape;
}

StackList<Operand *> worklist(projectedAddress->getFunction());
SmallPtrSet<Operand *, 32> visitedOperands;

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2 changes: 1 addition & 1 deletion test/SILOptimizer/copy_propagation_borrow.sil
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Expand Up @@ -501,6 +501,7 @@ bb0:
%copy1 = copy_value %borrow1 : $C
%borrow2 = begin_borrow %copy1 : $C
%addr = ref_element_addr %borrow2 : $C, #C.a
%ptr = address_to_pointer %addr : $*Int64 to $Builtin.RawPointer
cond_br undef, bb1, bb2
bb1:
// inside use
Expand Down Expand Up @@ -1201,4 +1202,3 @@ bb0(%0 : @guaranteed $C):
%7 = tuple ()
return %7 : $()
}

8 changes: 1 addition & 7 deletions test/SILOptimizer/liveness_unit.sil
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Expand Up @@ -222,19 +222,13 @@ bb4(%phi : @owned $C):
return %99 : $()
}

// A dead (ref_element_addr) projection is treated like a pointer
// escape for convenience. Make sure the pointer escape bubbles up
// through the phi and casts.
//
// CHECK-LABEL: testSSADeadRefElementAddr: ssa-liveness
// CHECK: SSA lifetime analysis: %0 = argument of bb0 : $C
// CHECK-NEXT: Incomplete liveness: Escaping address
// CHECK-NEXT: bb0: LiveOut
// CHECK-NEXT: bb2: LiveOut
// CHECK-NEXT: bb3: LiveWithin
// CHECK-NEXT: bb1: LiveOut
// CHECK: last user:
// CHECK-SAME: ref_element_addr %6 : $D, #D.object
// CHECK: ref_element_addr %6 : $D, #D.object
// CHECK-NEXT-LABEL: end running test 1 of 1 on testSSADeadRefElementAddr: ssa-liveness
sil [ossa] @testSSADeadRefElementAddr : $@convention(thin) (@guaranteed C) -> () {
bb0(%0 : @guaranteed $C):
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