Nate Chandler 1eafced6a2 [AllocBoxToStack] Don't destroy in dead-ends. ...

It is valid to leak a value on paths into dead-end regions.
Specifically, it is valid to leak an `alloc_box`.  Thus, "final
releases" in dead-end regions may not destroy the box and consequently
may not release its contents.  Therefore it's invalid to lower such final
releases to `dealloc_stack`s, let alone `destroy_addr`s.  The in-general
invalidity of that transformation results in miscompiling whenever a box
is leaked and its projected address is used after such final releases.

Fix this by not treating final releases as boundary markers of the
`alloc_box` and not lowering them to `destroy_addr`s and
`dealloc_stack`s.

rdar://158149082

2025-08-27 17:03:48 -07:00

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