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Merge pull request #85870 from atrick/comment-copyprop

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Add a FIXME to CopyPropagation to highlight an incomplete fix.
This commit is contained in:
Andrew Trick
2025-12-10 13:51:30 -08:00
committed by GitHub
parent f995144c1d 8cdef92334
commit 10e1be4387
1 changed files with 11 additions and 0 deletions
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11
lib/SILOptimizer/Utils/OSSACanonicalizeOwned.cpp
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@@ -201,6 +201,17 @@ bool OSSACanonicalizeOwned::computeCanonicalLiveness() {
// Conservatively treat a conversion to an unowned value as a pointer
// escape. Is it legal to canonicalize ForwardingUnowned?
//
// FIXME: BitwiseEscape is defined as a leaf use for liveness purposes. It
// implies that any use of those bits that require liveness are already
// handled by something like mark_dependence or fix_lifetime. It should
// be treated as an InstantaneousUse here not a PointerEscape. This was a
// workaround for invalid SIL which may still miscompile in other passes.
// Valid fixes are:
// 1. Compile the stdlib with lexical lifetimes.
// 2. Fix the source to correctly extendLifetime when bit-casting.
// 3. Conservatively change operand ownership for the SIL instruction to
// PointerEscape.
case OperandOwnership::ForwardingUnowned:
case OperandOwnership::PointerEscape:
case OperandOwnership::BitwiseEscape: