bytecodealliance · fitzgen · Apr 28, 2026 · Apr 25, 2026 · Apr 25, 2026 · Apr 28, 2026
diff --git a/.github/workflows/benchmarks.yml b/.github/workflows/benchmarks.yml
@@ -28,8 +28,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        # for now, limit this a bit
-        revision: ["main", "v38.0.3"]
+        revision: ["main"]
     env:
       REVISION: ${{ matrix.revision }}
     steps:
@@ -76,7 +75,7 @@ jobs:
       run: |
         cargo run benchmark \
         --engine=artifacts/wasmtime-main/libengine.so \
-        --engine=artifacts/wasmtime-v38.0.3/libengine.so \
+        --engine-flags "-Wgc -Wfunction-references" \
         --processes=4 \
         --iterations-per-process=1 \
         -- "${PARTITION_SUITE}"

diff --git a/Cargo.lock b/Cargo.lock
diff --git a/benchmarks/Dockerfile.wasm-tools b/benchmarks/Dockerfile.wasm-tools
@@ -0,0 +1,15 @@
+FROM rust:1.95
+
+# Install `wasm-tools`
+ENV CARGO_REGISTRIES_CRATES_IO_PROTOCOL=sparse
+RUN cargo install wasm-tools --version 1.247.0
+
+WORKDIR /usr/src
+ADD . benchmark-src
+WORKDIR /usr/src/benchmark-src
+
+# Run `wasm-tools wat2wasm` on each `.wat` file.
+RUN for x in *.wat; do wasm-tools wat2wasm "$x" -o "${x%.wat}.wasm"; done
+
+RUN mkdir /benchmark
+RUN cp *.wasm /benchmark/
diff --git a/benchmarks/all.suite b/benchmarks/all.suite
@@ -123,6 +123,7 @@ shootout/shootout-xchacha20.wasm
 spidermonkey/spidermonkey-markdown.wasm
 spidermonkey/spidermonkey-json.wasm
 spidermonkey/spidermonkey-regex.wasm
+splay/splay.wasm
 tinygo/tinygo-json.wasm
 tinygo/tinygo-regex.wasm
 tract-onnx-image-classification/benchmark.wasm

diff --git a/benchmarks/default.suite b/benchmarks/default.suite
@@ -5,4 +5,4 @@
 
 bz2/benchmark.wasm
 pulldown-cmark/benchmark.wasm
-spidermonkey/benchmark.wasm
+spidermonkey/spidermonkey-markdown.wasm
diff --git a/benchmarks/gc.suite b/benchmarks/gc.suite
@@ -0,0 +1 @@
+splay/splay.wasm
diff --git a/benchmarks/splay/Dockerfile b/benchmarks/splay/Dockerfile
@@ -0,0 +1 @@
+../Dockerfile.wasm-tools
diff --git a/benchmarks/splay/README.md b/benchmarks/splay/README.md
@@ -0,0 +1,29 @@
+# Splay
+
+A splay tree benchmark, ported to WebAssembly text format (WAT) using Wasm GC
+structs and arrays. It stresses the performance of the garbage collector.
+
+## Origin
+
+The original JavaScript source is from [JetStream's Octane/splay.js][source]; a
+similar version was previously published in Octane version 2, and it originally
+came from the V8 JavaScript engine project.
+
+[source]: https://github.com/WebKit/JetStream/blob/main/Octane/splay.js
+
+## Running
+
+Requires that `-Wgc -Wfunction-references` be passed to the underlying engine:
+
+```
+cargo run -- benchmark \
+    -e path/to/libwasmtime_bench_api.{so,dylib} \
+    --engine-flags="-Wgc -Wfunction-references" \
+    -- benchmarks/splay/splay.wasm
+```
+
+## License
+
+The original JavaScript source (`splay.js`) is copyright 2009 the V8 project
+authors and copyright 2015 Apple Inc., licensed under a BSD 3-clause license.
+See the header of `splay.js` for the full license text.
diff --git a/benchmarks/splay/default.input b/benchmarks/splay/default.input
@@ -0,0 +1 @@
+8000,800,5