Add zlib-wasm workload

As a replacement for the asm.js zlib workload in Octane that we removed.
Based on public domain zpipe.c example from https://www.zlib.net/zlib_how.html.
Compresses about 60KB of Wasm binary, and decompresses again.
Built with Emscripten, using zlib Emscripten port.
A single iteration takes around 50ms, the total line item around 2s.

Author: danleh

JetStreamDriver.js

@@ -2148,7 +2148,20 @@ const BENCHMARKS = [
         },
         async: true,
         testGroup: WasmGroup
-    })
+    }),
+    // zlib-wasm
+    new WasmEMCCBenchmark({
+        name: "zlib-wasm",
+        files: [
+            "./wasm/zlib/build/zlib.js",
+            "./wasm/zlib/benchmark.js",
+        ],
+        preload: {
+            wasmBinary: "./wasm/zlib/build/zlib.wasm",
+        },
+        iterations: 40,
+        testGroup: WasmGroup
+    }),
 ];
 
 // LuaJSFight tests

wasm-cli.js

@@ -35,6 +35,7 @@ testList = [
   "argon2-wasm",
   "argon2-wasm-simd",
   "8bitbench-wasm",
+  "zlib-wasm",
 ];
 
 // Reuse the full CLI runner, just with the subset of Wasm line items above.

wasm/zlib/benchmark.js

@@ -0,0 +1,34 @@
+// Copyright 2025 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+class Benchmark {
+  async runIteration() {
+    if (!Module._main)
+      await setupModule(Module);
+
+    Module.FS.writeFile('input', Module.wasmBinary);
+
+    const inputStr = Module.stringToNewUTF8('input');
+    const inputzStr = Module.stringToNewUTF8('input.z');
+    const inputzoutStr = Module.stringToNewUTF8('input.z.out');
+
+    for (let i = 0; i < 10; i++) {
+      Module._compressFile(inputStr, inputzStr);
+      Module._decompressFile(inputzStr, inputzoutStr);
+      if (Module.FS.stat('input').size !== Module.FS.stat('input.z.out').size) {
+        throw new Error("Length after decompression doesn't match");
+      }
+    }
+  }
+
+  validate() {
+    const input = Module.FS.readFile('input');
+    const outputRoundtrip = Module.FS.readFile('input.z.out');
+    for (let i = 0; i < input.length; i++) {
+      if (input[i] !== outputRoundtrip[i]) {
+        throw new Error("Content after decompression doesn't match at offset " + i);
+      }
+    }
+  }
+}

wasm/zlib/build.log

@@ -0,0 +1,6 @@
+Built on 2025-01-29T13:40:54Z
+Toolchain versions
+emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.73 (ac676d5e437525d15df5fd46bc2c208ec6d376a3)
+Getting zpipe.c example source...
+Building...
+Building done

wasm/zlib/build.sh

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+set -euo pipefail
+
+rm -rf build/
+rm -f src/zpipe.c
+
+touch build.log
+BUILD_LOG="$(realpath build.log)"
+echo "Built on $(date -u '+%Y-%m-%dT%H:%M:%SZ')" | tee "$BUILD_LOG"
+
+echo "Toolchain versions" | tee -a "$BUILD_LOG"
+emcc --version | head -n1 | tee -a "$BUILD_LOG"
+
+echo "Getting zpipe.c example source..." | tee -a "$BUILD_LOG"
+curl -o "src/zpipe.c" https://www.zlib.net/zpipe.c
+
+echo "Building..." | tee -a "$BUILD_LOG"
+mkdir build/
+emcc -o build/zlib.js \
+    -s WASM=1 -O2 \
+    -g1 --emit-symbol-map \
+    -s USE_ZLIB=1 -s FORCE_FILESYSTEM=1 \
+    -s MODULARIZE=1 -s EXPORT_NAME=setupModule -s EXPORTED_RUNTIME_METHODS=FS,stringToNewUTF8 -s EXPORTED_FUNCTIONS=_compressFile,_decompressFile \
+    src/zpipe.c src/main.c | tee -a "$BUILD_LOG"
+# If you want the native build for reference:
+# clang -o build/zlib -O2 -lz src/zpipe.c src/main.c
+
+echo "Building done" | tee -a "$BUILD_LOG"
+ls -lth build/