Add SWIFT_DEBUG_ENABLE_TASK_SLAB_ALLOCATOR, which is on by default. When turned off, async stack allocations call through to malloc/free. This allows memory debugging tools to be used on async stack allocations.
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
When it's available, use an open-coded allocator function that returns
an alloca without popping if the allocator is nullptr and otherwise
calls swift_coro_alloc. When it's not available, use the malloc
allocator in the synchronous context.
Rename duplicated `swift::fatalError` in `swiftRuntime` and `swift_Concurrency`.
Both `swiftRuntime` and `swift_Concurrency` had `swift::fatalError` implementation, but it causes symbol conflict with the `-static-stdlib` flag.
This patch removes one of the implementations in `swift_Concurrency` to avoid conflicts. Also added a test case to ensure that linking the Concurrency module with `-static-stdlib` works.
This issue was found by SwiftWasm test cases.
Both swiftRuntime and swift_Concurrency had swift::fatalError
implementation, but it causes symbol conflict when -static-stdlib.
This patch renames one of the impl in swift_Concurrency to avoid
conflict.
Also, do this for the initial slab for the task's allocator itself.
This avoids memory allocations for async-lets.
In case the async-task's memory demand does not exceed the initial slab size, it is now completely malloc-free.
The refcount bits of an async-let task are initialized to "immortal" so that ARC operations don't have an effect on the task.
Most of the async runtime functions have been changed to not
expect the task and executor to be passed in. When knowing the
task and executor is necessary, there are runtime functions
available to recover them.
The biggest change I had to make to a runtime function signature
was to swift_task_switch, which has been altered to expect to be
passed the context and resumption function instead of requiring
the caller to park the task. This has the pleasant consequence
of allowing the implementation to very quickly turn around when
it recognizes that the current executor is satisfactory. It does
mean that on arm64e we have to sign the continuation function
pointer as an argument and then potentially resign it when
assigning into the task's resume slot.
rdar://70546948
Use the StackAllocator as task allocator.
TODO: we could pass an initial pre-allocated first slab to the allocator, which is allocated on the stack or with the parent task's allocator.
rdar://problem/71157018
