When its operand has coroutine kind `yield_once_2`, a `begin_apply`
instruction produces an additional value representing the storage
allocated by the callee. This storage must be deallocated by a
`dealloc_stack` on every path out of the function. Like any other stack
allocation, it must obey stack discipline.
Add a setting to IRGenOptions and key off of it to emit yield_once_2
coroutines using either (1) the same code-path as yield_once coroutines
or (2) a new, not-yet implemented code-path.
Add flags to set the value in both directions. During bringup, by
default, use the existing caller-allocated ABI.
For now this will only be used for HopToMainActorIfNeeded thunks. I am creating
this now since in the past there has only been one option for creating
thunks... to create the thunk in SILGen using SILGenThunk. This code is hard to
test and there is a lot of it. By using an instruction here we get a few benefits:
1. We decouple SILGen from needing to generate new kinds of thunks. This means
that SILGenThunk does not need to expand to handle more thunks.
2. All thunks implemented via ThunkInst will be easy to test in a decoupled way
with SIL tests.
3. Even though this stabilizes the patient, we still have many thunks in SILGen
and various parts of the compiler. Over time, we can swap to this model,
allowing us to hopefully eventually delete SILGenThunk.
Motivated by need for protocol-based dynamic dispatch, which hasn't been possible in Embedded Swift due to a full ban on existentials. This lifts that restriction but only for class-bound existentials: Class-bound existentials are already (even in desktop Swift) much more lightweight than full existentials, as they don't need type metadata, their containers are typically 2 words only (reference + wtable pointer), don't incur copies (only retains+releases).
Included in this PR:
[x] Non-generic class-bound existentials, executable tests for those.
[x] Extension methods on protocols and using those from a class-bound existential.
[x] RuntimeEffects now differentiate between Existential and ExistentialClassBound.
[x] PerformanceDiagnostics don't flag ExistentialClassBound in Embedded Swift.
[x] WTables are generated in IRGen when needed.
Left for follow-up PRs:
[ ] Generic classes support
Some requirement machine work
Rename requirement to Value
Rename more things to Value
Fix integer checking for requirement
some docs and parser changes
Minor fixes
Adds sections `__TEXT,__swift_as_entry`, and `__TEXT,__swift_as_ret` that
contain relative pointers to async functlets modelling async function entries,
and function returns, respectively.
Emission of the sections can be trigger with the frontend option
`-Xfrontend -enable-async-frame-push-pop-metadata`.
This is done by:
* IRGen adding a `async_entry` function attribute to async functions.
* LLVM's coroutine splitting identifying continuation funclets that
model the return from an async function call by adding the function
attribute `async_ret`. (see #llvm-project/pull/9204)
* An LLVM pass that keys off these two function attribute and emits the
metadata into the above mention sections.
rdar://134460666
Metadata for foreign types are emitted lazily, when SILGen generates a
reference to it. Unfortunately, C++ reverse interop can also introduce
references to such metadata in the generated header when types are used
as generic arguments. This adds a type visitor to make note of the type
metadata use for those generic arguments in public APIs when C++ interop
is enabled.
rdar://132925256
The patch adds lowering of partial_apply instructions for coroutines.
This pattern seems to trigger a lot of type mismatch errors in IRGen, because
coroutine functions are not substituted in the same way as regular functions
(see the patch 07f03bd2 "Use pattern substitutions to consistently abstract
yields" for more details).
Other than that, lowering of partial_apply for coroutines is straightforward: we
generate another coroutine that captures arguments passed to the partial_apply
instructions. It calls the original coroutine for yields (first return) and
yields the resulting values. Then it calls the original function's continuation
for return or unwind, and forwards them to the caller as well.
After IRGen, LLVM's Coroutine pass transforms the generated coroutine (along with
all other coroutines) and eliminates llvm.coro.* intrinsics. LIT tests check
LLVM IR after this transformation.
Co-authored-by: Anton Korobeynikov <anton@korobeynikov.info>
Co-authored-by: Arnold Schwaighofer <aschwaighofer@apple.com>
rdar://129359370
Second part of direct error support. This implements direct errors for async functions. Instead of always returning typed errors indirectly, we are returning them directly when possible.
