This change adds a new type of cache (cache by type descriptor) to the protocol conformance lookup system. This optimization is beneficial for generic types, where the
same conformance can be reused across different instantiations of the generic type.
Key changes:
- Add a `GetOrInsertManyScope` class to `ConcurrentReadableHashMap` for performing
multiple insertions under a single lock
- Add type descriptor-based caching for protocol conformances
- Add environment variables for controlling and debugging the conformance cache
- Add tests to verify the behavior of the conformance cache
- Fix for https://github.com/swiftlang/swift/issues/82889
The implementation is controlled by the `SWIFT_DEBUG_ENABLE_CACHE_PROTOCOL_CONFORMANCES_BY_TYPE_DESCRIPTOR`
environment variable, which is enabled by default.
When targeting a platform that predates the introduction of isolated
deinit, make a narrow exception that allows main-actor-isolated deinit
to work through a special, inlineable entrypoint that is
back-deployed. This implementation
1. Calls into the real implementation when available, otherwise
2. Checks if we're on the main thread, destroying immediately when
we are, otherwise
3. Creates a new task on the main actor to handle destruction.
This implementation is less efficient than the implementation in the
runtime, but allows us to back-deploy this functionality as far back
as concurrency goes.
Fixes rdar://151029118.
The implementation of the ObjC -retain method saved a local variable and returned that after calling swift_retain, which forced it to create a stack frame. swift_retain returns the object being retained, so we can take advantage of that to have the compiler emit a tail call to it instead.
Without this, llvm would sometimes wrongly assume there's no indirect
accesses and the optimizations can lead to a runtime crash, by
optimizing away initializing options properly.
Resolves rdar://152548190
This only modifies the runtime function `swift_task_enqueueGlobalWithDeadline` to take new clock primitive to
interoperate with existing dispatch wall clock values.
This changes the isIsolatingCurrentContext function to return `Bool?`
and removes all the witness table trickery we did previously to detect
if it was implemented or not. This comes at a cost of trying to invoke
it always, before `checkIsolated`, but it makes for an simpler
implementation and more checkable even by third party Swift code which
may want to ask this question.
Along with the `withSerialExecutor` function, this now enables us to
check the isolation at runtime when we have an `any Actor` e.g. from
`#isolation`.
Updates SE-0471 according to
https://forums.swift.org/t/se-0471-improved-custom-serialexecutor-isolation-checking-for-concurrency-runtime/78834/
review discussions
This memory is part of the conformance cache concurrent hash map, so
when we clear the conformance cache, record each of the allocated
pointers within the concurrent map's free list. This way, it'll be
freed with the rest of the concurrent map when it's safe to do so.
Previously there was still a sneaky hop which caused ordering issues.
This introduced a specific test startSynchronously_order which checks
that the task enqueues indeed are "immediate" and cleans up how we
handle this.
This also prepares for the being discussed in SE review direction of
this API that it SHOULD be ALLOWED to actually hop and NOT be
synchronous at all IF the isolation is specified on the closure and is
DIFFERENT than the callers dynamic isolation.
This effectively implements "synchronously run right now if dynamically
on the exact isolation as requested by the closure; otherwise enqueue
the task as usual".
resolves rdar://149284186
cc @drexin
Function types aren't always trivially copyable, e.g. with address-discriminated signed pointers on ARM64e. Introduce a function_cast helper and use that instead.
* [SUA][IRGen] Add stub for swift_coroFrameAlloc that weakly links against the runtime function
This commit modifies IRGen to emit a stub function `__swift_coroFrameAllocStub` instead of the
newly introduced swift-rt function `swift_coroFrameAlloc`. The stub checks whether the runtime has the symbol
`swift_coroFrameAlloc` and dispatches to it if it exists, uses `malloc` otherwise. This ensures the
ability to back deploy the feature to older OS targets.
rdar://145239850
It's hard to tell why a crash occurred with just "Could not allocate memory." Modify the message to include the size/alignment, which will help distinguish between an actual lack of memory and a request for an excessively large allocation.
While we're in there, add \n to a bunch of other fatal error helper functions that didn't have it.
* [Concurrency] Detect non-default impls of isIsolatingCurrentContext
* [Concurrency] No need for trailing info about isIsolating... in conformance
* Apply changes from review
We don't emit signposts until something else has set them up, to avoid deadlocks when we're running in code that's involved in setting them up. But this means that Instruments will miss Concurrency events in a simple program that doesn't otherwise trigger setup of the logging system.
Since we must be in a platform binary if we're running in code that's setting up logging, we can check for that and only be lazy in platform binaries. Non-platform binaries can safely emit signposts eagerly.
rdar://142483658
Reorganise the Concurrency code so that it's possible to completely
implement executors (both main and global) in Swift.
Provide API to choose the desired executors for your application.
Also make `Task.Sleep` wait using the current executor, not the global
executor, and expose APIs on `Clock` to allow for conversion between
time bases.
rdar://141348916
Replace the pair of global actor type/conformance we are passing around with
a general "conformance execution context" that could grow new functionality
over time. Add three external symbols to the runtime:
* swift_conformsToProtocolWithExecutionContext: a conforms-to-protocol check
that also captures the execution context that should be checked before
using the conformance for anything. The only execution context right now
is for an isolated conformance.
* swift_isInConformanceExecutionContext: checks whether the function is
being executed in the given execution context, i.e., running on the
executor for the given global actor.
* swift_ConformanceExecutionContextSize: the size of the conformance
execution context. Client code outside of the Swift runtime can allocate
a pointer-aligned region of memory of this size to use with the runtime
functions above.
In the prior implementation of runtime resolution of isolated conformances,
the runtime had to look in both the protocol conformance descriptor and
in all conditional conformance requirements (recursively) to find any
isolated conformances. If it found one, it had to demangle the global
actor type to metadata. Since swift_conformsToProtocol is a hot path through
the runtime, we can't afford this non-constant-time work in the common
case.
Instead, cache the resolved global actor and witness table as part of the
conformance cache, so that we have access to this information every time
we look up a witness table for a conformance. Propagate this up through
various callers (e.g., generic requirement checking) to the point where
we either stash it in the cache or check it at runtime. This gets us down
to a very quick check (basically, NULL-or-not) for nonisolated conformances,
and just one check for isolated conformances.
Following the approach taken with the concurrency-specific type
descriptors, register a hook function for the "is current global actor"
check used for isolated conformances.
* [Concurrency] Initial steps for startSynchronously for Task
* [Concurrency] Rename to _startSynchronously while in development
* [Concurrency] StartSynchronously special executor to avoid switching
* startSynchronously bring back more info output
* [Concurrency] startSynchronously with more custom executor tests
* add missing ABI additions to test for x86
* [Concurrency] gyb generate _startSynchronously
* [Concurrency] %import dispatch for Linux startSynchronously test
* [Concurrency] Add TaskGroup.startTaskSynchronously funcs
* [Concurrency] DispatchSerialQueue does not exist on linux still
