[ownership-verifier] Teach the ownership verifier how to handle unreachable code. #7443
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rdar://29791263
…chable code. There are a few different use cases here: 1. In Raw SIL, no return folding may not have been run yet implying that a call to a no-return function /can/ have arbitrary control flow after it (consider mandatory inlined functions). We need to recognize that the region of code that is strictly post dominated by the no-return function is "transitively unreachable" and thus leaking is ok from that point. *Footnote 1*. 2. In Canonical and Raw SIL, we must recognize that unreachables and no-return functions constitute places where we are allowed to leak. rdar://29791263 ---- *Footnote 1*: The reason why this is done is since we want to emit unreachable code diagnostics when we run no-return folding. By leaving in the relevant code, we have preserved all of the SILLocations on that code allowing us to create really nice diagnostics.
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@swift-ci Please smoke test and merge |
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[ownership-verifier] Teach the ownership verifier how to handle unreachable code.
There are a few different use cases here:
In Raw SIL, no return folding may not have been run yet implying that a call
to a no-return function /can/ have arbitrary control flow after it (consider
mandatory inlined functions). We need to recognize that the region of code that
is strictly post dominated by the no-return function is "transitively
unreachable" and thus leaking is ok from that point. Footnote 1.
In Canonical and Raw SIL, we must recognize that unreachables and no-return
functions constitute places where we are allowed to leak.
rdar://29791263
Footnote 1: The reason why this is done is since we want to emit unreachable
code diagnostics when we run no-return folding. By leaving in the relevant code,
we have preserved all of the SILLocations on that code allowing us to create
really nice diagnostics.