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Tweak findTransitiveUsesForAddress implementation #63483

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Feb 7, 2023
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Tweak findTransitiveUsesForAddress implementation #63483

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8 changes: 7 additions & 1 deletion lib/SIL/Utils/OwnershipUtils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -131,7 +131,8 @@ bool swift::canOpcodeForwardOwnedValues(Operand *use) {
// Find all use points of \p guaranteedValue within its borrow scope. All uses
// are naturally dominated by \p guaranteedValue. If a PointerEscape is found,
// then no assumption can be made about \p guaranteedValue's lifetime. Therefore
// the use points are incomplete and this returns false.
// the use points are incomplete and this returns false. The escape point that
// was found must still be in \p usePoints to distinguish from dead addresses.
//
// Accumulate results in \p usePoints, ignoring existing elements.
//
Expand Down Expand Up @@ -982,6 +983,8 @@ swift::findTransitiveUsesForAddress(SILValue projectedAddress,

AddressUseKind result = AddressUseKind::NonEscaping;

// Record all uses that aren't transitively followed. These are either
// instanteneous uses of the addres, or cause a pointer escape.
auto leafUse = [foundUses](Operand *use) {
if (foundUses)
foundUses->push_back(use);
Expand Down Expand Up @@ -1011,6 +1014,7 @@ swift::findTransitiveUsesForAddress(SILValue projectedAddress,
// the apply to be a use point.
if (isa<PartialApplyInst>(user) || isa<AddressToPointerInst>(user)) {
result = meet(result, AddressUseKind::PointerEscape);
leafUse(op);
continue;
}
// First, eliminate "end point uses" that we just need to check liveness at
Expand All @@ -1035,6 +1039,7 @@ swift::findTransitiveUsesForAddress(SILValue projectedAddress,
if (isa<UnconditionalCheckedCastAddrInst>(user)
|| isa<MarkFunctionEscapeInst>(user)) {
assert(!user->hasResults());
leafUse(op);
continue;
}

Expand Down Expand Up @@ -1108,6 +1113,7 @@ swift::findTransitiveUsesForAddress(SILValue projectedAddress,
(*onError)(op);
}
result = meet(result, AddressUseKind::Unknown);
leafUse(op);
}
return result;
}
Expand Down