Fix #32: Implement exception handling. #38
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We do not use the tags in any translation yet.
That one is not a case class, and therefore does not depend on plenty of things from the scalalib that we do not support yet.
Because the latest nightly of Node.js does not support the latest specification for Wasm exceptions yet.
Including adding all the missing instructions and types for the latest specification of exception handling.
Currently, it does not correctly handle `Labeled/Return` pairs that cross its boundary.
sjrd
changed the title
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LGTM!
Thank you for updating the EH-spec related stuffs, I didn't know that there was an update on the spec recently WebAssembly/exception-handling#283 😅
IIUC, this implementation is able to catch the exception thrown from JS like
JS throws something else -> Scala.js catches it wrapped in a js.JavaScriptException
https://www.scala-js.org/doc/interoperability/exceptions.html
am I right?
| val resultLocals = resultType.map(fctx.addSyntheticLocal(_)) | ||
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| fctx.block() { doneLabel => | ||
| fctx.block(Types.WasmExnRef) { catchLabel => |
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(note) If the inner try block throws an uncaught exception, jump to the outside of this block (skipping ref.null exn)
Can we say the t.block is always TryCatch ?
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try_table is always a try..catch, yes. We have to implement the finally behavior manually on top of that.
(That's not uncommon for low-level bytecode formats. The JVM does the same.)
Unfortunately not yet. For that we will need a not-yet-approved addition to the exception handling feature. See WebAssembly/exception-handling#269 Currently all the wrap/unwrap thing does is allow to throw non- |
Gotcha, thanks! |
Unfortunately, we cannot write unit tests for
TryCatchandTryFinallyyet. The latest Node.js nightly build is still using an old version of v8 that does not support the latest spec for Wasm exception handling. However, it possible to run thesamplefrom a web browser when it containstry..catchandtry..finally.