build: parametrize the location of wasm-opt (#3454)

The wasm-opt binary may be available in different place than the local
directory (`./wasm-opt`) – for example, in /usr/bin/wasm-opt.
Similarly to the other parametrized WASM build options,
use WASM_OPT environment variable to identify the wanted binary,
with fallback to the previous value.

Even with the environment variable available,
the `hasOptimizer` is kept to make the optimization optional.

Signed-off-by: Jan Staněk <jstanek@redhat.com>

CONTRIBUTING.md

@@ -159,6 +159,7 @@ an unbundled version instead of bundling one in `libnode.so`.
 To enable this, pass `EXTERNAL_PATH=/path/to/global/node_modules/undici` to `build/wasm.js`.
 Pass this path with `loader.js` appended to `--shared-builtin-undici/undici-path` in Node.js's `configure.py`.
 If building on a non-Alpine Linux distribution, you may need to also set the `WASM_CC`, `WASM_CFLAGS`, `WASM_LDFLAGS` and `WASM_LDLIBS` environment variables before running `build/wasm.js`.
+Similarly, you can set the `WASM_OPT` environment variable to utilize your own `wasm-opt` optimizer.
 
 <a id="benchmarks"></a>
 ### Benchmarks

build/wasm.js

@@ -14,6 +14,7 @@ const WASM_CC = process.env.WASM_CC || 'clang'
 let WASM_CFLAGS = process.env.WASM_CFLAGS || '--sysroot=/usr/share/wasi-sysroot -target wasm32-unknown-wasi'
 let WASM_LDFLAGS = process.env.WASM_LDFLAGS || ''
 const WASM_LDLIBS = process.env.WASM_LDLIBS || ''
+const WASM_OPT = process.env.WASM_OPT || './wasm-opt'
 
 // For compatibility with Node.js' `configure --shared-builtin-undici/undici-path ...`
 const EXTERNAL_PATH = process.env.EXTERNAL_PATH
@@ -77,7 +78,7 @@ const hasApk = (function () {
   try { execSync('command -v apk'); return true } catch (error) { return false }
 })()
 const hasOptimizer = (function () {
-  try { execSync('./wasm-opt --version'); return true } catch (error) { return false }
+  try { execSync(`${WASM_OPT} --version`); return true } catch (error) { return false }
 })()
 if (hasApk) {
   // Gather information about the tools used for the build
@@ -97,7 +98,7 @@ ${join(WASM_SRC, 'src')}/*.c \
 ${WASM_LDLIBS}`, { stdio: 'inherit' })
 
 if (hasOptimizer) {
-  execSync(`./wasm-opt ${WASM_OPT_FLAGS} -o ${join(WASM_OUT, 'llhttp.wasm')} ${join(WASM_OUT, 'llhttp.wasm')}`, { stdio: 'inherit' })
+  execSync(`${WASM_OPT} ${WASM_OPT_FLAGS} -o ${join(WASM_OUT, 'llhttp.wasm')} ${join(WASM_OUT, 'llhttp.wasm')}`, { stdio: 'inherit' })
 }
 writeWasmChunk('llhttp.wasm', 'llhttp-wasm.js')
 
@@ -109,7 +110,7 @@ ${join(WASM_SRC, 'src')}/*.c \
 ${WASM_LDLIBS}`, { stdio: 'inherit' })
 
 if (hasOptimizer) {
-  execSync(`./wasm-opt ${WASM_OPT_FLAGS} --enable-simd -o ${join(WASM_OUT, 'llhttp_simd.wasm')} ${join(WASM_OUT, 'llhttp_simd.wasm')}`, { stdio: 'inherit' })
+  execSync(`${WASM_OPT} ${WASM_OPT_FLAGS} --enable-simd -o ${join(WASM_OUT, 'llhttp_simd.wasm')} ${join(WASM_OUT, 'llhttp_simd.wasm')}`, { stdio: 'inherit' })
 }
 writeWasmChunk('llhttp_simd.wasm', 'llhttp_simd-wasm.js')