This commit changes JobFlags storage to be 32bits, but leaves the runtime
API expressed in terms of size_t. This allows us to pack an Id in the
32bits we freed up.
The offset of this Id in the AsyncTask is an ABI constant. This way
introspection tools can extract the currently running task identifier
without any need for special APIs.
Previously, they were storing a low-bit flag that indicated that they
were a default actor. Using an extra inhabitant frees up the low bit
for future use without being conspicuously more expensive to check.
Allow runtime metadata queries to determine if a "class" (in the
runtime) is actually an actor by adding a bit to the class context
descriptor's type-specific kind flags.
Implements rdar://77073762.
Actor inheritance was removed in the second revision of SE-0306. Remove
the ability to inherit actors.
Note that this doesn't fully eliminate all vestigates of inheritance
from actors. There are simplifications that need to be performed
still, e.g., there's no need to distinguish
designated/convenience/required initializers. That will follow.
As part of bringup, specifically in order to support storing the size of
the async context as the first entry in the thick context, the
optimization that allows the partial application of a single refcounted
object to avoid the allocation of a thick context was disabled.
Now that we have async function pointers for partial application
forwarders, that rationale is moot, so, here, the optimization is
restored.
rdar://76372871
- stop storing the parent task in the TaskGroup at the .swift level
- make sure that swift_taskGroup_isCancelled is implied by the parent
task being cancelled
- make the TaskGroup structs frozen
- make the withTaskGroup functions inlinable
- remove swift_taskGroup_create
- teach IRGen to allocate memory for the task group
- don't deallocate the task group in swift_taskGroup_destroy
To achieve the allocation change, introduce paired create/destroy builtins.
Furthermore, remove the _swiftRetain and _swiftRelease functions and
several calls to them. Replace them with uses of the appropriate builtins.
I should probably change the builtins to return retained, since they're
working with a managed type, but I'll do that in a separate commit.
PE requires a singleton metadata initialization for this class when
MachO and ELF don't, IIRC because of the inability to handle pointers
into other libraries from data sections.
For ordinary memory-management reasons, this should only ever
happen when there will be no more uses of the actor outside of the
actor runtime. The actor runtime, meanwhile, doesn't care about
anything except the default-actor control state of the actor. So
we can just allow the rest of the actor to be destructed when it
isn't needed anymore, then destroy the actor state and deallocate
the object when we get around to switching off the executor.
This does assume that the task doesn't do anything which semantically
detects the executor it's on before switching off it, since doing so
might read a bogus executor. However, we should only get an executor
in a zombie state like this when a hop has been removed or reordered,
and detection events should count as inhibiting that and forcing the
true executor to be switched to (and thus detected).
(But maybe lifetime optimization can make this happen? Maybe we
need semantic detection to filter out zombie executors.)
Repurpose mangling operator `Y` as an umbrella operator that covers new attributes on function types. Free up operators `J`, `j`, and `k`.
```
async ::= 'Ya' // 'async' annotation on function types
sendable ::= 'Yb' // @Sendable on function types
throws ::= 'K' // 'throws' annotation on function types
differentiable ::= 'Yjf' // @differentiable(_forward) on function type
differentiable ::= 'Yjr' // @differentiable(reverse) on function type
differentiable ::= 'Yjd' // @differentiable on function type
differentiable ::= 'Yjl' // @differentiable(_linear) on function type
```
Resolves rdar://76299796.
Previously, because partial apply forwarders for async functions were
not themselves fully-fledged async functions, they were not able to
handle dynamic functions. Specifically, the reason was that it was not
possible to produce an async function pointer for the partial apply
forwarder because the size to be used was not knowable.
Thanks to https://github.com/apple/swift/pull/36700, that cause has been
eliminated. With it, partial apply forwarders are fully-fledged async
functions and in particular have their own async function pointers.
Consequently, it is again possible for these partial apply forwarders to
handle non-constant function pointers.
Here, that behavior is restored, by way of reverting part of
ee63777332 while preserving the ABI it
introduced.
rdar://76122027
External async functions pointers can't be used to clone the async
context size from.
Future improvement: reinstate the previous optimization of reusing the
context.
rdar://76029017
The comment in LowerHopToActor explains the design here.
We want SILGen to emit hops to actors, ignoring executors,
because it's easier to fully optimize in a world where deriving
an executor is a non-trivial operation. But we also want something
prior to IRGen to lower the executor derivation because there are
useful static optimizations we can do, such as doing the derivation
exactly once on a dominance path and strength-reducing the derivation
(e.g. exploiting static knowledge that an actor is a default actor).
There are probably phase-ordering problems with doing this so late,
but hopefully they're restricted to situations like actors that
share an executor. We'll want to optimize that eventually, but
in the meantime, this unblocks the executor work.
The VS2017 started to succeed while executing
test/IRGen/async/throwing.swift, but it is marked as XFAIL for
OS=windows-msvc. To avoid failing the test in VS2019, only mark it as
unsupported in MSVC_VER=15.0 (VS2017), which will avoid running the
test.
`async_task_detached.swift` seems to fail with an `ACCESS_VIOLATION`
exit status, but seems to pass in VS2019, so also mark it as
`UNSUPPORTED` for VS2017 only.
All these problems are tracked in SR-14333.
The immediate desire is to minimize the set of ABI dependencies
on the layout of an ExecutorRef. In addition to that, however,
I wanted to generally reduce the code size impact of an unsafe
continuation since it now requires accessing thread-local state,
and I wanted resumption to not have to create unnecessary type
metadata for the value type just to do the initialization.
Therefore, I've introduced a swift_continuation_init function
which handles the default initialization of a continuation
and returns a reference to the current task. I've also moved
the initialization of the normal continuation result into the
caller (out of the runtime), and I've moved the resumption-side
cmpxchg into the runtime (and prior to the task being enqueued).
Throwing functions pass the error result in `swiftself` to the resume
partial function.
Therefore, `() async -> ()` to `() async throws -> ()` is not ABI compatible.
TODO: go through remaining failing IRGen async tests and replace the
illegal convert_functions.
