It works well enough now that it should be an acceptable replacement for both
borrowing and consuming switches that works in more correct situations than the
previous implementation. This does however expose a few known issues that I'll
try to fix in follow ups:
- overconsumes cause verifier errors instead of raising diagnostics (rdar://125381446)
- cases with multiple pattern labels aren't yet supported (rdar://125188955)
- copyable types with the `borrowing` or `consuming` modifiers should probably use
noncopyable pattern matching.
The `BorrowingSwitch` flag is still necessary to enable the surface-level syntax
changes (switches without `consume` and the `_borrowing` modifier, for instance).
enabled. If two modules are in the same package and package cmo is enabled,
v-table or witness-table calls should not be generated at the use site in the
client module. Modified conformance serialization check to allow serializing
witness thunks.
Also reordered SIL functions bottom-up so the most nested referenced functions
can be serialized first. Allowed serializing a function if a shared definition
(e.g. function `print`). Added a check for resilient mode wrt struct instructions.
Added tests for SIL tables and resilient mode on/off.
rdar://124632670
Builds on https://github.com/apple/swift/pull/72286.
Use a more forgiving strategy when handling potentially invalid conformances
during SILGen. Conformances may be erroneously marked invalid during witness
resolution, even when they can still be successfully emitted, so we can't bail
out of witness table emission if the invalid bit is set. Instead, just ignore
placeholders and missing methods in the witness table emitter and trust that if
an error was diagnosed during resolution that compilation will be aborted.
Resolves rdar://125947349
This diagnostic is useful around silgen_name where it validates that we do not
have any weird collisions. Sadly, it just points where one of the conflicting
elements is... with this patch, we also emit an error on the other function if
we have a SILLocation.
When erasing a pseudogeneric value in SILGen, we actually treat
the value as if it had the type `any AnyObject`, while in Sema,
it's an archetype. This requires SILGen to look up conformances
again instead of using the ones in the ErasureExpr.
I fixed a bunch of small issues around here that resulted in a bunch of radars
being fixed. Specifically:
1. I made it so that we treat function_refs that are from an actor isolated
function as actor isolated instead of sendable.
2. I made it so that autoclosures which return global actor isolated functions
are treated as producing a global actor isolated function.
3. I made it so that we properly handle SILGen code patterns produced by
Sendable GlobalActor isolated things.
rdar://125452372
rdar://121954871
rdar://121955895
rdar://122692698
If an expression refers to noncopyable storage, then default to performing
a borrowing switch, where `let` bindings in patterns borrow out of the
matched value. If an expression refers to a temporary value or explicitly
uses the `consume` keyword, then perform a consuming switch, where
`let` bindings take ownership of corresponding parts of the matched value.
Allow `_borrowing` to still be used to explicitly bind a pattern variable
as a borrow, with no-implicit-copy semantics for copyable values.
* Allow normal function results of @yield_once coroutines
* Address review comments
* Workaround LLVM coroutine codegen problem: it assumes that unwind path never returns.
This is not true to Swift coroutines as unwind path should end with error result.
This issue can come up when a value is initially statically disconnected, but
after we performed dataflow, we discovered that it was actually actor isolated
at the transfer point, implying that we are not actually transferring.
Example:
```swift
@MainActor func testGlobalAndGlobalIsolatedPartialApplyMatch2() {
var ns = (NonSendableKlass(), NonSendableKlass())
// Regions: (ns.0, ns.1), {(mainActorIsolatedGlobal), @MainActor}
ns.0 = mainActorIsolatedGlobal
// Regions: {(ns.0, ns.1, mainActorIsolatedGlobal), @MainActor}
// This is not a transfer since ns is already main actor isolated.
let _ = { @MainActor in
print(ns)
}
useValue(ns)
}
```
To do this, I also added to SILFunction an actor isolation that SILGen puts on
the SILFunction during pre function visitation. We don't print it or serialize
it for now.
rdar://123474616
Failing to map the type of an isolation capture into context
caused assertions in type lowering. Fixes the build of the
swift-distributed-actors package.
The runtime function `swift_willThrowTyped` takes its argument
`@in_guaranteed`. In opaque values SIL, that's passed directly. Don't
store non-address errors before passing them to the function.
I'm not sure there's any way to test this right now. We don't naturally
emit multiple function conversions on a single operand, and the only way
to get a similar effect is to coerce, which interrupts the application of
`@_inheritActorContext`. So I think this is dead code until we add closure
isolation controls, and even then it might be dead unless we allow coercion
of isolated closures, which maybe we won't. But it's the right thing to do
in the abstract, and I was thinking of it now.
This allows us to propagate abstraction patterns from optional parameters
all the way to closure emission, which optimizes some code patterns but
(more importantly) propagates our knowledge that we're converting to an
`@isolated(any)` function type down to closure emission, allowing us to
set the isolation correctly.
There are still some conversion cases missing --- if we can't combine
conversions for whatever reason, we should at least shift our knowledge
that we need to produce an `@isolated(any)` type down, the same way that
we shift it when emitting a closure that we can't directly emit in the
target abstraction pattern. But this completes the obvious cases of
peepholing for closure emission.
For address-only types, a temporary was emitted with the same debug variable
and same scope as the instruction it is moved to after entering a shared case,
but it would have a different type, which would create a conflict.
The better way to fix this would probably to use a different scope for both,
but the variable is moved immediately anyway.
Fix the check here to go by `isMoveOnly` on the lowered type rather than
`canBeCopyable` on the declaration so that we correctly emit the
semantic initialization for types that are `~Copyable` in their most
generic form. Fixes rdar://125101955.
When a closure throws a generic error type, we were retrieving the
substituted error type (involving archetypes) when we needed to be
working with the interface type.
Fixes rdar://124484012.
None of these additional test cases actually uncovered any problems but it
seems valuable to have them.
Also, add pretty stack traces for a couple paths through SILGen.
Force resolution of value witnesses and check the conformance for validity
before proceeding to witness table emission in SILGen to avoid crashing because
of unexpected errors in the AST.
Resolves rdar://123027739
Don't attempt a SILCombine transform on `select_enum` that inserts a copy when an
enum is noncopyable. Adjust the cleanup handling for a consuming optional chain to
ensure a `destroy_value` still gets emitted on the `none` path; this shouldn't
actually matter since `none` is a trivial case, but the memory verifier isn't
that fancy during OSSA, and we can optimize it later. Fixes rdar://124426918.
