[Strings] Work around ref.cast not working on string views, and add fuzzing #6549
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tlively
reviewed
Apr 26, 2024
| heapType == HeapType::stringview_iter) { | ||
| // We cannot cast string views to/from anything, so the input must also | ||
| // be a view. | ||
| assert(curr->ref->type.getHeapType() == heapType); |
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I don't think this will handle casts to bottom correctly. If a string view is cast to (ref none), we should just emit (unreachable) because that cast cannot possibly succeed. If a string view is cast to (ref null none), I haven't thought of anything better than emitting (ref.is_null) (if (result nullref) (then (ref.null none)) (else (unreachable)).
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This isn't comprehensive atm, I guess, yeah, but it should handle all the things the fuzzer and the optimizer emit. I'm not sure if it's worth handling more things.
tlively
approved these changes
Apr 26, 2024
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As suggested in #6434 (comment) , lower
ref.castof string viewsto
ref.as_non_nullin binary writing. It is a simple hack that avoids theproblem of V8 not allowing them to be cast.
Add fuzzing support for the last three core string operations, after which
that problem becomes very frequent.
Also add yet another
makeTrappingRefUsethat was missing in thatfuzzer code.