wasm-coremark

CoreMark 1.01 ported to WebAssembly.

CoreMark is a simple, yet sophisticated benchmark that is designed specifically to test the functionality of a processor core. Running CoreMark produces a single-number score allowing users to make quick comparisons between processors.

Source: https://github.com/eembc/coremark

Online demo: here

Builds

• coremark.wasm - WASI app
• coremark-minimal.wasm - Simple wasm module with minimal runtime dependencies
• coremark-emcc.* - Emscripten build

Running WASI app

Use any WASI-compatible runtime to run it directly:

# Wasm3
wasm3 coremark.wasm

# kanaka/wac
wax coremark.wasm

# wasmtime
wasmtime coremark.wasm

# WAVM
wavm run coremark.wasm

# Wasmer
wasmer run --singlepass coremark.wasm
wasmer run --cranelift coremark.wasm
wasmer run --llvm coremark.wasm

# Wasmer-JS (V8)
wasmer-js run coremark.wasm

# Wasmer-JS (V8 interpreter)
node --wasm-interpret-all $(which wasmer-js) run coremark.wasm

With no arguments the benchmark picks its own iteration count, aiming for a run of 10 seconds or more. All four CoreMark parameters can be given instead:

# seed1 seed2 seed3 iterations
wasm3 coremark.wasm 0x0 0x0 0x66 60000        # performance run
wasm3 coremark.wasm 0x3415 0x3415 0x66 60000  # validation run

Pass 0 as the iteration count to keep the automatic calibration. A run of under 10 seconds reports a score, but is not a valid CoreMark result.

Running Emscripten version

You can open it with your browser.

Run a local copy:

python3 -m http.server 8000
# visit http://localhost:8000/coremark-emcc.html

Using Node.js:

node coremark-emcc.js

Running minimal version

You can open it with your browser.

Here are some examples of how to load and execute it using different engines:

• coremark-minimal.html - JavaScript example using your browser's engine.
• coremark-minimal.mjs - Node.js example using V8.
• coremark-minimal.py - Python 3 example using Wasm3 engine.
• wasmi-coremark - Rust example using Wasmtime, Wasm3, wasmi.

Both local examples expect coremark-minimal.wasm next to them:

# Node.js
node coremark-minimal.mjs

# Python 3, via the wasm3 bindings
pip install pywasm3
./coremark-minimal.py

Serve the directory to run the browser example:

python3 -m http.server 8000
# visit http://localhost:8000/coremark-minimal.html

To run with any wasm runtime:

1. You need to provide an u64 env.clock_ms() function, which should return current time in milliseconds.
2. Call f32 run() function. It should take 12..20 seconds to execute and return a CoreMark result.

Wasm3 supplies clock_ms itself, so its CLI can run the module directly:

wasm3 --func run coremark-minimal.wasm

Build instructions

build.sh clones the CoreMark sources at a pinned revision, builds each target in its own scratch copy under build/, and drops the result in the repository root:

export WASI_SDK=/path/to/wasi-sdk-34.0-x86_64-linux

./build.sh              # coremark.wasm and coremark-minimal.wasm
./build.sh emcc         # coremark-emcc.{html,js,wasm}, needs emcc on PATH
./build.sh native       # coremark.elf, for comparison against the host

Three ports live in ports/:

• ports/wasi builds on CoreMark's posix port.
• ports/emcc is the same posix port, for the Emscripten build.
• ports/minimal is a bare-module port derived from CoreMark's barebones one: no WASI, no libc I/O, no command line. It takes the clock from an env.clock_ms import and exports run.

Wasm features

All three wasm builds enable the Lime1 feature set, plus tail calls:

mutable-globals      bulk-memory-opt
multivalue           extended-const
sign-ext             call-indirect-overlong
nontrapping-fptoint  tail-call

An engine has to implement all of them to load the modules. Drop WASM_FEATURES in build.sh to a smaller set to target an older one; LLVM spells the Lime1 half of the list as -mcpu=lime1.

Releases

.github/workflows/build.yml builds every push and pull request and uploads the binaries as a run artifact. Pushing a v* tag publishes them as a GitHub release:

git tag v1.0.0
git push origin v1.0.0

The same workflow deploys the demo pages from main to GitHub Pages.

Toolchain versions

The toolchains are pinned in the workflow (WASI_SDK_VERSION, EMSCRIPTEN_VERSION), and each build records the exact versions in toolchain.txt next to the binaries:

# WASI
wasi-sdk 34.0
clang version 23.1.0-wasi-sdk

# EMCC
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 6.0.8
clang version 24.0.0git