Simplify modular runtime initialization promise#27059
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Unify and simplify the promise and dependency resolution mechanism for modularized builds (both MODULARIZE=1 and MODULARIZE=instance). Previously, the codebase maintained separate tracking variables like moduleRtn and readyPromiseResolve alongside complex external Promise wrappers across distinct JS postamble files. This created unnecessary complexity and redundant boilerplate. This change replaces ad-hoc external Promise assignment with direct async/await initialization flows inside the core runtime postamble. This also fixes the MODULARIZE=instance dependency order issue.
This is an automatic change generated by tools/maint/rebaseline_tests.py. The following (10) test expectation files were updated by running the tests with `--rebaseline`: ``` test/codesize/audio_worklet_wasm.expected.js updated codesize/test_codesize_minimal_esm.json: 2521 => 2468 [-53 bytes / -2.10%] codesize/test_codesize_minimal_pthreads.json: 26075 => 26081 [+6 bytes / +0.02%] codesize/test_codesize_minimal_pthreads_memgrowth.json: 26484 => 26490 [+6 bytes / +0.02%] codesize/test_minimal_runtime_code_size_audio_worklet.json: 16399 => 16399 [+0 bytes / +0.00%] codesize/test_minimal_runtime_code_size_hello_webgl2_wasm.json: 13200 => 13161 [-39 bytes / -0.30%] codesize/test_minimal_runtime_code_size_hello_webgl2_wasm2js.json: 18572 => 18534 [-38 bytes / -0.20%] codesize/test_minimal_runtime_code_size_hello_webgl2_wasm_singlefile.json: 15046 => 15015 [-31 bytes / -0.21%] codesize/test_minimal_runtime_code_size_hello_webgl_wasm.json: 12738 => 12699 [-39 bytes / -0.31%] codesize/test_minimal_runtime_code_size_hello_webgl_wasm2js.json: 18098 => 18060 [-38 bytes / -0.21%] Average change: -0.36% (-2.10% - +0.02%) ```
sbc100
reviewed
Jun 5, 2026
| #if MODULARIZE | ||
| await new Promise((resolve) => { | ||
| dependenciesFulfilled = resolve; | ||
| }); |
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Can this just be a single line await new Promise((resolve) => dependenciesFulfilled = resolve);?
| { | ||
| const url = await import('node:url'); | ||
| const isMainModule = url.pathToFileURL(process.argv[1]).href === import.meta.url; | ||
| const isMainModule = process.argv[1] && url.pathToFileURL(process.argv[1]).href === import.meta.url; |
| readyPromiseResolve = resolve; | ||
| readyPromiseReject = reject; | ||
| }); | ||
| } |
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This is awesome. Since this file doesn't do anything but inject these assertions now I wonder if it should just be removed (perhaps as a followup)?
| if settings.MODULARIZE and settings.MODULARIZE != 'instance': | ||
| modularize() | ||
| elif settings.USE_CLOSURE_COMPILER: | ||
| elif settings.USE_CLOSURE_COMPILER and not settings.MODULARIZE: |
| if settings.MODULARIZE: | ||
| module_extern_file = shared.get_temp_files().get('.js', prefix='emcc_modularize_extern_') | ||
| module_extern_file.write(b'/** @suppress {duplicate} */\nvar Module;\n') | ||
| module_extern_file.close() |
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If the contents of this file are just constant we can't we just check this in as a file in src/closure-externs/?
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Maybe just add to the existing modularize-externs.js?
sbc100
reviewed
Jun 5, 2026
| doRun(); | ||
| resolve(); | ||
| }, 1); | ||
| }); |
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This code looks kind of weird.. perhaps it should have a comment?
sbc100
reviewed
Jun 5, 2026
| text = text.replace(/\bawait run\(\)/g, 'EMSCRIPTEN$AWAIT(run())'); | ||
| text = text.replace(/\bawait instantiatePromise\b/g, 'EMSCRIPTEN$AWAIT(instantiatePromise)'); | ||
| text = text.replace(/\bawait init\(\)/g, 'EMSCRIPTEN$AWAIT(init())'); | ||
| } |
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Maybe make this new code into its own named function? Something like mangleUnsupportedSyntax ? or some better name?
I wonder what knock on effects it will have that we now do this in processMacros vs preprocess? IIRC there are times when we do one but not the other.
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Unify and simplify the promise and dependency resolution mechanism for
modularized builds (both MODULARIZE=1 and MODULARIZE=instance).
Previously, the codebase maintained separate tracking variables like
moduleRtn and readyPromiseResolve alongside complex external Promise
wrappers across distinct JS postamble files. This created unnecessary
complexity and redundant boilerplate.
This change replaces ad-hoc external Promise assignment with direct
async/await initialization flows inside the core runtime postamble. This
also fixes the MODULARIZE=instance dependency order issue.