Support Embedded Swift in the core engine - #395
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The interpreter shares one untyped-throws execution pipeline on every platform: Embedded Swift 6.5 supports untyped throws and `any Error`, so no typed-throws variants or error-carrying trap cases are needed, and every instruction (including atomics and exception handling) stays available. Capability differences are expressed through traits where possible, and `#if $Embedded` remains only for true compile necessities: - The blocking half of AtomicParkingLot is gated on the MultiThread trait (single-threaded builds cannot create shared memories, so `atomic.wait`/`notify` trap before reaching the parking lot; an inert stub satisfies the type checker). Wait deadlines are computed via a new ParkingDeadline platform type instead of using ContinuousClock at the instruction site. CI trait lists now include the default-on MultiThread trait, which they had silently dropped. - The profiler is gated on the FileSystem trait (it writes its trace to a file), and the instruction-dumping code (`wasmkit explore`) is gated on a new default-on Disassembler trait. - Direct threading is disabled under Embedded; it requires the swifttailcc convention, which Embedded targets (like WASI) do not provide. - mmap-based virtual memory is excluded on targets without an OS. - `Instruction.emitImmediate(to:)` is now generated so the translator avoids calling default protocol methods on existentials, and key-path literals are replaced with closures on shared paths.
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Part of the incremental upstreaming of Embedded Swift support (#357). Follows #394.
This makes the core engine build and run with
-enable-experimental-feature Embedded. Embedded Swift 6.5 supports untyped throws andany Error, so the interpreter shares one untyped execution pipeline on every platform — no typed-throws variants, no error-carrying trap cases, and every instruction (including atomics and exception handling) stays available under Embedded.Capability differences are expressed through traits where possible;
#if $Embeddedremains only for true compile necessities:AtomicParkingLot's blocking half is gated on the MultiThread trait. Single-threaded builds can't create shared memories, soatomic.wait/notifytrap before reaching the parking lot; an inert stub satisfies the type checker. Wait deadlines go through a newParkingDeadlineplatform type instead ofContinuousClockat the instruction site. The CI trait lists now include the default-on MultiThread trait, which they had silently dropped.wasmkit explore) is gated on a new default-on Disassembler trait.Instruction.emitImmediate(to:)is generated so the translator avoids calling default protocol methods on existentials; a few key-path literals become closures.Verified on hardware: the ESP32-C6 build and a QEMU run of the demo (guest→host calls, and a host error thrown from a host function caught by identity in the embedder) pass. The example project and portable smoke test land in a follow-up PR.