Improves OSSALifetimeCompletion to handle trivial variables when running from
SILGenCleanup. This only affects lifetime dependence diagnostics.
For the purpose of lifetime diagnostics, trivial local variables are only valid
within their lexical scope. Sadly, SILGen only know how to insert cleanup code
on normal function exits. SILGenCleanup relies on lifetime completion to fix
lifetimes on dead end paths.
%var = move_value [var_decl]
try_apply %f() : $..., normal bb1, error error
error:
extend_lifetime %var <=== insert this
unreachable
This allows Span to depend on local unsafe pointers AND be used within
throwing closures:
_ = a.withUnsafeBufferPointer {
let buffer = $0
let view = Span(_unsafeElements: buffer)
return view.withUnsafeBufferPointer(\.count)
}
Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
When visiting consumes, also visit `extend_lifetime` instructions.
These instructions are not lifetime ending, but together with the
consumes, they enclose the users of a value.
Add a flag to LinearLiveness to control whether these instructions are
added so that the verifier can use verify that all such instructions
appear outside the linear lifetime boundary (not including them).
In the C++ sources it is slightly more convenient to dump to stderr than
to print to stdout, but it is rather more unsightly to print to stderr
from the Swift sources. Switch to stdout. Also allows the dump
functions to be marked debug only.
Encapsulate all the complexity of reborrows and guaranteed phi in 3
ownership liveness interfaces:
LinerLiveness, InteriorLiveness, and ExtendedLiveness.
