Support all garbage collector tests by zherczeg · Pull Request #2622 · WebAssembly/wabt

zherczeg · 2025-06-27T09:35:23Z

This patch adds support for all tests in testsuite/proposals/gc. Two tests are still missing.

zherczeg · 2025-06-30T13:29:38Z

It looks like garbage collection tests are finally working. It took me 4 months, but the initial version of garbage collection support is completed. I think I understand the concept of references in WebAssembly, and know why it works that way. The code probably needs a lot of changes.

from: WebAssembly/wabt#2622 https://github.com/zherczeg/wabt/tree/gc_tests Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu

from: https://github.com/zherczeg/wabt/tree/gc_tests (1917fb3) WebAssembly/wabt#2622 Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu

note: this requires a version of wabt which doesn't exist yet, see WebAssembly/wabt#2622

kevmoo · 2026-03-05T16:25:39Z

So exciting to see this moving along!

zherczeg · 2026-03-05T16:35:28Z

Thank you! I try to update this patchset reguraly. The longer term aim is full wasm 3.0 support, but I also do some work on WebAssembly Components. Do you need this code for something?

kevmoo · 2026-03-05T16:36:47Z

I work with the dart2wasm team. We have our own wasm2wat impl for our output. I'd be awesome if we could use the default tools.

kevmoo · 2026-03-07T17:43:24Z

If you want a sample file: https://bouncing.web.app/main.dart.wasm

kevmoo · 2026-05-07T15:56:18Z

Sweet!

zherczeg · 2026-05-08T03:19:23Z

I am updating these patches but I don't know when they land. The first one in the set has a birthday soon!

zherczeg · 2026-09-30T05:12:40Z

I have some good news. Due to the recent improvements of wabt, with this patchset the webassembly 3.0 spec tests can be run with wabt.

kripken

Hi! While I'm not normally a wabt reviewer, I do know a bit about WasmGC, and I think it would be great for the community to get this patchset landed, so I took a bit of a look now.

kripken · 2026-09-30T18:46:39Z

    case Opcode::I32X4RelaxedTruncF64X2UZero:
+    case Opcode::RefEq:
      // 0 immediates, 1 operand.
      instr.kind = InstrKind::Imm_0_Op_1;


Doesn't RefEq takes two operands, the two references to compare for equality?

Do we not have a test for RefEq? (If we do, how did it pass?)

Nice catch! Probably just pure luck, since only the number of immediates matter (the values are on the stack, they don't need to be read from the byte stream). There are 3 PR-s for the patchset, I will fix this in the relevant one.

Oh, is the order of the 3 PRs listed somewhere?

#2607 #2618 and this one. They built on the top of each other. The first contains the first patch, the second one the first two patches, and this one is all three patches.

kripken · 2026-09-30T18:56:41Z

+    *out_value = Type(is_nullable ? Type::RefNull : Type::Ref,
+                      static_cast<Index>(heap_type));
+  }
+  return Result::Ok;


I was expecting to see a check that the type index is in bounds (less than the number of types) - should that not be here?

No. Webassenbly has rules for malformed and invalid forms. Malformed data should cause a fail during parsing. However, an invalid webassembly should be accepted, and validation should reject it later. Hence an invalid webassembly file could be read and written back without issues.

This patch supports parsing the new GC types - Abstract types - Recursive types - Composite types The patch also improves type comparison.

zherczeg force-pushed the gc_tests branch 3 times, most recently from e973c0b to 2426298 Compare June 30, 2025 11:39

zherczeg force-pushed the gc_tests branch 3 times, most recently from 645b133 to 1917fb3 Compare July 9, 2025 10:20

matetokodi added a commit to matetokodi/walrus that referenced this pull request Jul 15, 2025

Update WABT files from zherczeg:gc_tests

82a68dc

from: WebAssembly/wabt#2622 https://github.com/zherczeg/wabt/tree/gc_tests Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu

matetokodi added a commit to matetokodi/walrus that referenced this pull request Jul 16, 2025

Update wabt files from zherczeg:gc_tests

7b0d681

from: https://github.com/zherczeg/wabt/tree/gc_tests (1917fb3) WebAssembly/wabt#2622 Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu

matetokodi added a commit to matetokodi/walrus that referenced this pull request Jul 18, 2025

Update wabt files from zherczeg:gc_tests

e718421

from: https://github.com/zherczeg/wabt/tree/gc_tests (1917fb3) WebAssembly/wabt#2622 Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu

matetokodi added a commit to matetokodi/walrus that referenced this pull request Jul 22, 2025

Update wabt files from zherczeg:gc_tests

9dc1e52

from: https://github.com/zherczeg/wabt/tree/gc_tests (1917fb3) WebAssembly/wabt#2622 Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu

matetokodi added a commit to matetokodi/walrus that referenced this pull request Jul 22, 2025

Update wabt files from zherczeg:gc_tests

fb5575d

from: https://github.com/zherczeg/wabt/tree/gc_tests (1917fb3) WebAssembly/wabt#2622 Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu

ksh8281 pushed a commit to Samsung/walrus that referenced this pull request Jul 31, 2025

Update wabt files from zherczeg:gc_tests

bab2edb

from: https://github.com/zherczeg/wabt/tree/gc_tests (1917fb3) WebAssembly/wabt#2622 Signed-off-by: Máté Tokodi mate.tokodi@szteszoftver.hu

bfredl added a commit to bfredl/forklift that referenced this pull request Nov 11, 2025

CHAIN LIES

be4e0e1

note: this requires a version of wabt which doesn't exist yet, see WebAssembly/wabt#2622

zherczeg force-pushed the gc_tests branch 2 times, most recently from 46dac3d to 692da15 Compare February 4, 2026 10:08

zherczeg force-pushed the gc_tests branch from 692da15 to 4fc4a52 Compare March 5, 2026 11:30

zherczeg force-pushed the gc_tests branch from 4fc4a52 to 94f7884 Compare March 7, 2026 05:45

zherczeg force-pushed the gc_tests branch 2 times, most recently from 743218b to 595a459 Compare March 13, 2026 06:17

kevmoo mentioned this pull request Mar 14, 2026

[wasm2c] Fix exception testing on macOS #2716

Merged

zherczeg force-pushed the gc_tests branch 2 times, most recently from 9e1178d to afe6c80 Compare March 27, 2026 06:28

zherczeg force-pushed the gc_tests branch from afe6c80 to b7ef665 Compare April 14, 2026 12:14

zherczeg force-pushed the gc_tests branch 2 times, most recently from 29627a7 to 4247008 Compare May 7, 2026 11:17

zherczeg force-pushed the gc_tests branch 2 times, most recently from 7aa8c6e to 2eddd7f Compare June 17, 2026 09:17

zherczeg force-pushed the gc_tests branch 3 times, most recently from 89a2eae to 55f7c9c Compare July 6, 2026 07:15

zherczeg force-pushed the gc_tests branch from 55f7c9c to ffc8a27 Compare July 24, 2026 14:31

zherczeg force-pushed the gc_tests branch 2 times, most recently from 8c7f8d3 to 1ffa928 Compare August 6, 2026 11:27

zherczeg mentioned this pull request Aug 9, 2026

Fix assertion parsing typed refs in GC struct/array fields (#2750) #2809

Closed

5 tasks done

zherczeg force-pushed the gc_tests branch 4 times, most recently from 47290eb to 61e8e04 Compare August 26, 2026 09:29

zherczeg force-pushed the gc_tests branch from 61e8e04 to e792834 Compare August 31, 2026 08:58

zherczeg force-pushed the gc_tests branch from e792834 to 1d23766 Compare September 15, 2026 08:11

zherczeg force-pushed the gc_tests branch from 1d23766 to 5f554f9 Compare September 30, 2026 04:50

zherczeg force-pushed the gc_tests branch from 5f554f9 to 2cc039f Compare September 30, 2026 07:01

kripken reviewed Sep 30, 2026

View reviewed changes

zherczeg added 3 commits October 1, 2026 06:58

Implement Garbage Collector type system

27ae482

This patch supports parsing the new GC types - Abstract types - Recursive types - Composite types The patch also improves type comparison.

Implement GC opcodes

2821e49

Support all gc tests

036bcaa

zherczeg force-pushed the gc_tests branch from 2cc039f to 036bcaa Compare October 1, 2026 07:58

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