Specifically, I am refactoring out the code that converts actor/Optional<any
Actor> to an executor in preparation for adding code to LowerHopToExecutor that
handles Builtin.ImplicitIsolationActor.
The only actual functional change is that I made getExecutorForOptionalActor
support being invoked when generating code (i.e. when its SILBuilder has an
insertion point at the end of the block). It previously assumed that it would
always have a real SILInstruction as an insertion point. The changes can be seen
in the places where we now check if the insertion point equals the end of a
block. Its very minor and due to conditional control flow doesn't have any
actual impact given the manner that the code today is generated. This came up in
a subsequent commit when I reuse this code to generate a helper function for
converting Builtin.ImplicitIsolationActor to Builtin.Executor.
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)
In preparation for inserting mark_dependence instructions for lifetime
dependencies early, immediately after SILGen. That will simplify the
implementation of borrowed arguments.
Marking them unresolved is needed to make OSSA verification
conservative until lifetime dependence diagnostics runs.
in LowerHopToActor.
In order to project an optional executor value from an optional actor value,
the executor lowering needs to modify the CFG. This is done by splitting
LowerHopToActor into two passes. The first pass records all actor operands
of hop_to_executor and extract_executor instructions and records the
dominating instruction that will derive the executor value. The second pass
iterates over the multi-map of dominating instructions, derives the executor
value, and rewrites the operands of all reachable hop_to_executor and
extract_executor instructions to reuse that executor value.
The dependent 'value' may be marked 'nonescaping', which guarantees that the
lifetime dependence is statically enforceable. In this case, the compiler
must be able to follow all values forwarded from the dependent 'value', and
recognize all final (non-forwarded, non-escaping) use points. This implies
that `findPointerEscape` is false. A diagnostic pass checks that the
incoming SIL to verify that these use points are all initially within the
'base' lifetime. Regular 'mark_dependence' semantics ensure that
optimizations cannot violate the lifetime dependence after diagnostics.
* [Executors][Distributed] custom executors for distributed actor
* harden ordering guarantees of synthesised fields
* the issue was that a non-default actor must implement the is remote check differently
* NonDefaultDistributedActor to complete support and remote flag handling
* invoke nonDefaultDistributedActorInitialize when necessary in SILGen
* refactor inline assertion into method
* cleanup
* [Executors][Distributed] Update module version for NonDefaultDistributedActor
* Minor docs cleanup
* we solved those fixme's
* add mangling test for non-def-dist-actor
The function prologue of async funclets inherits its source location
from the hop_to_executor instruction. This makes it easier to produce
logical backtraces, since the PC in logical frames will always point
to the start if the function.
rdar://89776340
* [Distributed] dist actor always has default executor (currently)
* [Distributed] extra test for missing makeEncoder
* [DistributedDecl] Add DistributedActorSystem to known SDK types
* [DistributedActor] ok progress on getting the system via witness
* [Distributed] allow hop-to `let any: any X` where X is DistActor
* [Distributed] AST: Add an accessor to determine whether type is distributed actor
- Classes have specialized method on their declarations
- Archetypes and existentials check their conformances for
presence of `DistributedActor` protocol.
* [Distributed] AST: Account for distributed members declared in class extensions
`getConcreteReplacementForProtocolActorSystemType` should use `getSelfClassDecl`
otherwise it wouldn't be able to find actor if the member is declared in an extension.
* [Distributed] fix ad-hoc requirement checks for 'mutating'
[PreChecker] LookupDC might be null, so account for that
* [Distributed] Completed AST synthesis for dist thunk
* [Distributed][ASTDumper] print pretty distributed in right color in AST dumps
* wip on making the local/remote calls
* using the _local to mark the localCall as known local
* [Distributed] fix passing Never when not throwing
* fix lifetime of mangled string
* [Distributed] Implement recordGenericSubstitution
* [Distributed] Dont add .
* [Distributed] dont emit thunk when func broken
* [Distributed] fix tests; cleanups
* [Distributed] cleanup, move is... funcs to DistributedDecl
* [Distributed] Remove SILGen for distributed thunks, it is in Sema now!
* [Distributed] no need to check stored props in protocols
* remote not used flag
* fix mangling test
* [Distributed] Synthesis: Don't re-use AST nodes for `decodeArgument` references
* [Distributed] Synthesis: Make sure that each thunk parameter has an internal name
* [Distributed/Synthesis] NFC: Add a comment regarding empty internal parameter names
* [Distributed] NFC: Adjust distributed thunk manglings in the accessor section test-cases
* cleanup
* [Distributed] NFC: Adjust distributed thunk manglings in the accessor thunk test-cases
* review follow ups
* xfail some linux tests for now so we can land the AST thunk
* Update distributed_actor_remote_functions.swift
Co-authored-by: Pavel Yaskevich <xedin@apache.org>
LowerHopToActor expected either an optional executor or an actor, and
would crash when given a non-optional executor. This patch adds the
wrapping to produce an optional executor from a non-optional executor in
the pass to avoid crashing.
The pass uses SILBuilder instant to create instructions and does not
set SILDebugScope.
Due to this, SILVerifier correctly asserts that basic blocks contain non-contiguous
lexical scopes at -Onone.
The long term fix would be to replace SILBuilder instance in the pass with
SILBuilderContext and use SILBuilderWithScope so that such bugs do not come up.
SILGen this builtin to a mandatory hop_to_executor with an actor type
operand.
e.g.
Task.detached {
Builtin.hopToActor(MainActor.shared)
await suspend()
}
Required to fix a bug in _runAsyncMain.
- Introduce an UnownedSerialExecutor type into the concurrency library.
- Create a SerialExecutor protocol which allows an executor type to
change how it executes jobs.
- Add an unownedExecutor requirement to the Actor protocol.
- Change the ABI for ExecutorRef so that it stores a SerialExecutor
witness table pointer in the implementation field. This effectively
makes ExecutorRef an `unowned(unsafe) SerialExecutor`, except that
default actors are represented without a witness table pointer (just
a bit-pattern).
- Synthesize the unownedExecutor method for default actors (i.e. actors
that don't provide an unownedExecutor property).
- Make synthesized unownedExecutor properties `final`, and give them
a semantics attribute specifying that they're for default actors.
- Split `Builtin.buildSerialExecutorRef` into a few more precise
builtins. We're not using the main-actor one yet, though.
Pitch thread:
https://forums.swift.org/t/support-custom-executors-in-swift-concurrency/44425
Through various means, it is possible for a synchronous actor-isolated
function to escape to another concurrency domain and be called from
outside the actor. The problem existed previously, but has become far
easier to trigger now that `@escaping` closures and local functions
can be actor-isolated.
Introduce runtime detection of such data races, where a synchronous
actor-isolated function ends up being called from the wrong executor.
Do this by emitting an executor check in actor-isolated synchronous
functions, where we query the executor in thread-local storage and
ensure that it is what we expect. If it isn't, the runtime complains.
The runtime's complaints can be controlled with the environment
variable `SWIFT_UNEXPECTED_EXECUTOR_LOG_LEVEL`:
0 - disable checking
1 - warn when a data race is detected
2 - error and abort when a data race is detected
At an implementation level, this introduces a new concurrency runtime
entry point `_checkExpectedExecutor` that checks the given executor
(on which the function should always have been called) against the
executor on which is called (which is in thread-local storage). There
is a special carve-out here for `@MainActor` code, where we check
against the OS's notion of "main thread" as well, so that `@MainActor`
code can be called via (e.g.) the Dispatch library's
`DispatchQueue.main.async`.
The new SIL instruction `extract_executor` performs the lowering of an
actor down to its executor, which is implicit in the `hop_to_executor`
instruction. Extend the LowerHopToExecutor pass to perform said
lowering.
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.
