OSSA lifetime canonicalization can take a very long time in certain
cases in which there are large basic blocks. to mitigate this, add logic
to skip walking the liveness boundary for extending liveness to dead
ends when there aren't any dead ends in the function.
Updates `DeadEndBlocks` with a new `isEmpty` method and cache to
determine if there are any dead-end blocks in a given function.
(cherry picked from commit 1f3f830fc7)
The new function stripAccessAndAccessStorageCasts is analogous to the
existing function stripAccessAndIdentityCasts but differs in that the
latter uses isAccessStorageIdentityCast whereas the new function uses
isAccessStorageCast.
This prevents simplification and SILCombine passes to remove (alive) `mark_dependence_addr`.
The instruction is conceptually equivalent to
```
%v = load %addr
%d = mark_dependence %v on %base
store %d to %addr
```
Therefore the address operand has to be defined as writing to the address.
Outside of the resilience domain, they have to be treated as opaque and therefore potentially
addressable-for-dependencies, but inside of the resilience domain, we may take advantage of
knowing the type layout to load indirect parameters out of memory and break the (unnecessary)
dependency on a fixed memory location. Fixes rdar://151268401.
We do still however have problems when the type is actually `@_addressableForDependencies`
inside of its resilience domain (rdar://151500074). I'll fix that in a follow up.
This will cause tests today to crash since even though we are placing the
isolation now, to make it easier to read, I left in the old isolation selecting
code. This code uses the witness's isolation instead of the requirement's
isolation which is incorrect since the protocol witness thunk needs to look the
requirement from an ABI perspective since the two must be substitutable. The
crash comes from the ABI verification I added in earlier commits.
(cherry picked from commit ff1cbea576)
Also, make it more tolerant to instructions and builtins, which are not explicitly handled.
This avoids crashes when new instructions are added. We got lucky that this didn't happen so far.
Add a note explaining that dependence on closure captures is not
supported. Otherwise, the diagnostics are very confusing:
"it depends on a closure capture; this is not yet supported"
(cherry picked from commit 83b0ce1098)
When a generic function has potentially Escapable outputs, those outputs
declare lifetime dependencies, which have no effect when substitution
leads to those types becoming `Escapable` in a concrete context.
This means that type substitution should canonically eliminate lifetime
dependencies targeting Escapable parameters or returns, and that
type checking should allow a function value with potentially-Escapable
lifetime dependencies to bind to a function type without those dependencies
when the target of the dependencies is Escapable.
Fixes rdar://147533059.
Specifically:
1. I made it so that thunks from caller -> concurrent properly ignore the
isolated parameter of the thunk when calling the concurrent function.
rdar://148112362
2. I made it so that thunks from concurrent -> caller properly create a
Optional<any Actor>.none and pass that into the caller function.
rdar://148112384
3. I made it so that in cases where we are assigning an @Sendable caller to a
non-sendable caller variable, we allow for the conversion as long as the
parameters/results are sendable as well.
rdar://148112532
4. I made it so that when we generate a thunk from @execution(caller) ->
@GlobalActor, we mangle in @GlobalActor into the thunk.
rdar://148112569
5. I discovered that due to the way we handle function conversion expr/decl ref
expr, we were emitted two thunks when we assigned a global @caller function to a
local @caller variable. The result is that we would first cast from @caller ->
@concurrent and then back to @caller. The result of this would be that the
@caller function would always be called on the global queue.
rdar://148112646
I also added a bunch of basic tests as well that showed that this behavior was
broken.
When performing a dynamic cast to an existential type that satisfies
(Metatype)Sendable, it is unsafe to allow isolated conformances of any
kind to satisfy protocol requirements for the existential. Identify
these cases and mark the corresponding cast instructions with a new flag,
`[prohibit_isolated_conformances]` that will be used to indicate to the
runtime that isolated conformances need to be rejected.
I am doing this in preparation for adding the ability to represent in the SIL
type system that a function is global actor isolated. Since we have isolated
parameters in SIL, we do not need to represent parameter, nonisolated, or
nonisolated caller in the type system. So this should be sufficient for our
purposes.
I am adding this since I need to ensure that we mangle into thunks that convert
execution(caller) functions to `global actor` functions what the global actor
is. Otherwise, we cannot tell the difference in between such a thunk and a thunk
that converts execution(caller) to execution(concurrent).
This is a value operation that can work just fine on lowered types,
so there's no need to carry along a formal type. Make the value/address
duality clearer, and enforce it in the verifier.
