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Add initial packed waitqueue type #8323

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Add initial packed waitqueue type #8323

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65db363
Add initial packed waitqueue type
stevenfontanella Feb 12, 2026
1d8ea09
Use binary code from V8
stevenfontanella Feb 13, 2026
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4 changes: 4 additions & 0 deletions src/ir/possible-constant.h
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Original file line number Diff line number Diff line change
Expand Up @@ -120,8 +120,12 @@ struct PossibleConstantValues {
value = val.and_(Literal(uint32_t(0xffff)));
}
break;
case Field::WaitQueue:
WASM_UNREACHABLE("not implemented");
break;
case Field::not_packed:
WASM_UNREACHABLE("unexpected packed type");
break;
}
}

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2 changes: 2 additions & 0 deletions src/parser/contexts.h
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Expand Up @@ -149,6 +149,7 @@ struct NullTypeParserCtx {

StorageT makeI8() { return Ok{}; }
StorageT makeI16() { return Ok{}; }
StorageT makeWaitQueue() { return Ok{}; }
StorageT makeStorageType(TypeT) { return Ok{}; }

FieldT makeFieldType(StorageT, Mutability) { return Ok{}; }
Expand Down Expand Up @@ -308,6 +309,7 @@ template<typename Ctx> struct TypeParserCtx {

StorageT makeI8() { return Field(Field::i8, Immutable); }
StorageT makeI16() { return Field(Field::i16, Immutable); }
StorageT makeWaitQueue() { return Field(Field::WaitQueue, Immutable); }
StorageT makeStorageType(TypeT type) { return Field(type, Immutable); }

FieldT makeFieldType(FieldT field, Mutability mutability) {
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4 changes: 4 additions & 0 deletions src/parser/parsers.h
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Expand Up @@ -717,6 +717,10 @@ template<typename Ctx> Result<typename Ctx::FieldT> storagetype(Ctx& ctx) {
if (ctx.in.takeKeyword("i16"sv)) {
return ctx.makeI16();
}
if (ctx.in.takeKeyword("waitqueue"sv)) {
return ctx.makeWaitQueue();
}

auto type = valtype(ctx);
CHECK_ERR(type);
return ctx.makeStorageType(*type);
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5 changes: 3 additions & 2 deletions src/wasm-binary.h
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Expand Up @@ -369,8 +369,9 @@ enum EncodedType {
f64 = -0x4, // 0x7c
v128 = -0x5, // 0x7b
// packed types
i8 = -0x8, // 0x78
i16 = -0x9, // 0x77
i8 = -0x8, // 0x78
i16 = -0x9, // 0x77
waitQueue = -0x24, // 0x5c
// reference types
nullfuncref = -0xd, // 0x73
nullexternref = -0xe, // 0x72
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4 changes: 4 additions & 0 deletions src/wasm-interpreter.h
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Expand Up @@ -2752,6 +2752,10 @@ class ExpressionRunner : public OverriddenVisitor<SubType, Flow> {
memcpy(&i, p, sizeof(i));
return truncateForPacking(Literal(int32_t(i)), field);
}
case Field::WaitQueue: {
WASM_UNREACHABLE("waitqueue not implemented");
break;
}
}
WASM_UNREACHABLE("unexpected type");
}
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1 change: 1 addition & 0 deletions src/wasm-type.h
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Expand Up @@ -701,6 +701,7 @@ struct Field {
not_packed,
i8,
i16,
WaitQueue,
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@kripken kripken Feb 13, 2026

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This looks inconsistent with the existing values, in particular not_packed vs WaitQueue?

Which proposal is this from btw? I'd like to read the background.

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@stevenfontanella stevenfontanella Feb 13, 2026

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The context is in the linked issue and in particular in Thomas's issue. I'm implementing the second paragraph in that issue which is WaitQueue as a packed type. Since I'm implementing it as a packed type, I think this is the right place for this but let me know if I got it wrong.

The problem that we're trying to solve is that WaitQueue needs to be partially opaque, but we'd also like existing struct accessors to be able to mutate its control word.

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@stevenfontanella stevenfontanella Feb 13, 2026

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Just realized that you meant the naming. I don't mind changing it, but it looks like most enums values in this repo use PascalCase, maybe we should change not_packed to NotPacked instead? Either way is ok to me.

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@kripken kripken Feb 13, 2026

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Yeah, you're right, maybe it should be NotPacked. I guess we can leave that as separate from this PR then.

Reading some of the discussion on the substance, this seems... complicated.

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@kripken kripken Feb 13, 2026

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Let's make a decision though on planning to rename to NotPacked, or something else. I think I'd be in favor of that.

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@stevenfontanella stevenfontanella Feb 13, 2026

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Sounds good to me! Will change it in the next PR.

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@kripken kripken Feb 13, 2026

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sg, though actually let's wait for @tlively to weigh in, as maybe there was a reason for not_packed that I don't recall...

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@tlively tlively Feb 14, 2026

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NotPacked sgtm

} packedType; // applicable iff type=i32
Mutability mutable_;

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6 changes: 6 additions & 0 deletions src/wasm/wasm-binary.cpp
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Expand Up @@ -1996,6 +1996,8 @@ void WasmBinaryWriter::writeField(const Field& field) {
o << S32LEB(BinaryConsts::EncodedType::i8);
} else if (field.packedType == Field::i16) {
o << S32LEB(BinaryConsts::EncodedType::i16);
} else if (field.packedType == Field::WaitQueue) {
o << S32LEB(BinaryConsts::EncodedType::waitQueue);
} else {
WASM_UNREACHABLE("invalid packed type");
}
Expand Down Expand Up @@ -2717,6 +2719,10 @@ void WasmBinaryReader::readTypes() {
auto mutable_ = readMutability();
return Field(Field::i16, mutable_);
}
if (typeCode == BinaryConsts::EncodedType::waitQueue) {
auto mutable_ = readMutability();
return Field(Field::WaitQueue, mutable_);
}
// It's a regular wasm value.
auto type = makeType(typeCode);
auto mutable_ = readMutability();
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5 changes: 5 additions & 0 deletions src/wasm/wasm-type.cpp
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Expand Up @@ -1483,6 +1483,9 @@ unsigned Field::getByteSize() const {
return 2;
case Field::PackedType::not_packed:
return 4;
case Field::PackedType::WaitQueue:
WASM_UNREACHABLE("waitqueue not implemented");
break;
}
WASM_UNREACHABLE("impossible packed type");
}
Expand Down Expand Up @@ -1874,6 +1877,8 @@ std::ostream& TypePrinter::print(const Field& field) {
os << "i8";
} else if (packedType == Field::PackedType::i16) {
os << "i16";
} else if (packedType == Field::PackedType::WaitQueue) {
os << "waitqueue";
} else {
WASM_UNREACHABLE("unexpected packed type");
}
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9 changes: 9 additions & 0 deletions test/lit/waitqueue.wast
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Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
;; RUN: wasm-opt %s -all --roundtrip -S -o - | filecheck %s --check-prefix=RTRIP
(module
;; RTRIP: (type $t (struct (field waitqueue)))
(type $t (struct (field waitqueue)))

;; use $t so roundtripping doesn't drop the definition
(global (ref null $t) (ref.null $t))
)
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