Move addOnInit and ATINIT into a JS library. #23433

brendandahl · 2025-01-16T18:40:21Z

Make it so the addOnInit code is not emitted if it is not needed.

Since preamble.js is not a library I changed the call to
__wasm_call_ctors to be inlined like it is in MINIMAL_RUNTIME. I also
had to add various dependencies on addOnInit and __ATINIT__.

Make it so the `addOnInit` code is not emitted if it is not needed. Since preamble.js is not a library I changed the call to `__wasm_call_ctors` to be inlined like it is in MINIMAL_RUNTIME. I also had to add various dependencies on addOnInit and __ATINIT__.

This is an automatic change generated by tools/maint/rebaseline_tests.py. The following (97) test expectation files were updated by running the tests with `--rebaseline`: ``` browser/test_small_js_flags.js.size: 4341 => 4356 [+15 bytes / +0.35%] other/codesize/test_codesize_cxx_ctors1.gzsize: 8343 => 8335 [-8 bytes / -0.10%] other/codesize/test_codesize_cxx_ctors1.jssize: 20273 => 20251 [-22 bytes / -0.11%] other/codesize/test_codesize_cxx_ctors1.size: 129211 => 129218 [+7 bytes / +0.01%] other/codesize/test_codesize_cxx_ctors2.gzsize: 8327 => 8324 [-3 bytes / -0.04%] other/codesize/test_codesize_cxx_ctors2.jssize: 20241 => 20229 [-12 bytes / -0.06%] other/codesize/test_codesize_cxx_ctors2.size: 128623 => 128630 [+7 bytes / +0.01%] other/codesize/test_codesize_cxx_except.gzsize: 9343 => 9337 [-6 bytes / -0.06%] other/codesize/test_codesize_cxx_except.jssize: 24041 => 24018 [-23 bytes / -0.10%] other/codesize/test_codesize_cxx_except.size: 170879 => 170886 [+7 bytes / +0.00%] other/codesize/test_codesize_cxx_except_wasm.gzsize: 8294 => 8280 [-14 bytes / -0.17%] other/codesize/test_codesize_cxx_except_wasm.jssize: 20166 => 20143 [-23 bytes / -0.11%] other/codesize/test_codesize_cxx_except_wasm.size: 142162 => 142169 [+7 bytes / +0.00%] other/codesize/test_codesize_cxx_except_wasm_exnref.gzsize: 8294 => 8280 [-14 bytes / -0.17%] other/codesize/test_codesize_cxx_except_wasm_exnref.jssize: 20166 => 20143 [-23 bytes / -0.11%] other/codesize/test_codesize_cxx_except_wasm_exnref.size: 144708 => 144715 [+7 bytes / +0.00%] other/codesize/test_codesize_cxx_lto.gzsize: 8357 => 8352 [-5 bytes / -0.06%] other/codesize/test_codesize_cxx_lto.jssize: 20348 => 20325 [-23 bytes / -0.11%] other/codesize/test_codesize_cxx_mangle.gzsize: 9349 => 9341 [-8 bytes / -0.09%] other/codesize/test_codesize_cxx_mangle.jssize: 24041 => 24018 [-23 bytes / -0.10%] other/codesize/test_codesize_cxx_mangle.size: 232724 => 232731 [+7 bytes / +0.00%] other/codesize/test_codesize_cxx_noexcept.gzsize: 8343 => 8335 [-8 bytes / -0.10%] other/codesize/test_codesize_cxx_noexcept.jssize: 20273 => 20251 [-22 bytes / -0.11%] other/codesize/test_codesize_cxx_noexcept.size: 131774 => 131781 [+7 bytes / +0.01%] other/codesize/test_codesize_cxx_wasmfs.gzsize: 3564 => 3553 [-11 bytes / -0.31%] other/codesize/test_codesize_cxx_wasmfs.jssize: 7676 => 7654 [-22 bytes / -0.29%] other/codesize/test_codesize_cxx_wasmfs.size: 169181 => 169188 [+7 bytes / +0.00%] other/codesize/test_codesize_files_js_fs.gzsize: 7647 => 7634 [-13 bytes / -0.17%] other/codesize/test_codesize_files_js_fs.jssize: 18820 => 18798 [-22 bytes / -0.12%] other/codesize/test_codesize_files_wasmfs.gzsize: 2804 => 2792 [-12 bytes / -0.43%] other/codesize/test_codesize_files_wasmfs.jssize: 5984 => 5963 [-21 bytes / -0.35%] other/codesize/test_codesize_hello_O0.gzsize: 7883 => 7882 [-1 bytes / -0.01%] other/codesize/test_codesize_hello_O0.jssize: 20983 => 20964 [-19 bytes / -0.09%] other/codesize/test_codesize_hello_O0.size: 15101 => 15110 [+9 bytes / +0.06%] other/codesize/test_codesize_hello_O1.gzsize: 2658 => 2646 [-12 bytes / -0.45%] other/codesize/test_codesize_hello_O1.jssize: 6837 => 6808 [-29 bytes / -0.42%] other/codesize/test_codesize_hello_O2.gzsize: 2320 => 2307 [-13 bytes / -0.56%] other/codesize/test_codesize_hello_O2.jssize: 4778 => 4757 [-21 bytes / -0.44%] other/codesize/test_codesize_hello_O3.gzsize: 2278 => 2267 [-11 bytes / -0.48%] other/codesize/test_codesize_hello_O3.jssize: 4720 => 4699 [-21 bytes / -0.44%] other/codesize/test_codesize_hello_Os.gzsize: 2278 => 2267 [-11 bytes / -0.48%] other/codesize/test_codesize_hello_Os.jssize: 4720 => 4699 [-21 bytes / -0.44%] other/codesize/test_codesize_hello_Oz.gzsize: 2278 => 2267 [-11 bytes / -0.48%] other/codesize/test_codesize_hello_Oz.jssize: 4720 => 4699 [-21 bytes / -0.44%] other/codesize/test_codesize_hello_dylink.gzsize: 5992 => 5994 [+2 bytes / +0.03%] other/codesize/test_codesize_hello_dylink.jssize: 13241 => 13230 [-11 bytes / -0.08%] other/codesize/test_codesize_hello_export_nothing.gzsize: 1678 => 1665 [-13 bytes / -0.77%] other/codesize/test_codesize_hello_export_nothing.jssize: 3633 => 3614 [-19 bytes / -0.52%] other/codesize/test_codesize_hello_wasmfs.gzsize: 2278 => 2267 [-11 bytes / -0.48%] other/codesize/test_codesize_hello_wasmfs.jssize: 4720 => 4699 [-21 bytes / -0.44%] other/codesize/test_codesize_libcxxabi_message_O3.gzsize: 1874 => 1862 [-12 bytes / -0.64%] other/codesize/test_codesize_libcxxabi_message_O3.jssize: 3996 => 3977 [-19 bytes / -0.48%] other/codesize/test_codesize_libcxxabi_message_O3_standalone.gzsize: 1912 => 1907 [-5 bytes / -0.26%] other/codesize/test_codesize_libcxxabi_message_O3_standalone.jssize: 4044 => 4034 [-10 bytes / -0.25%] other/codesize/test_codesize_mem_O3.gzsize: 2326 => 2315 [-11 bytes / -0.47%] other/codesize/test_codesize_mem_O3.jssize: 4888 => 4867 [-21 bytes / -0.43%] other/codesize/test_codesize_mem_O3_grow.gzsize: 2474 => 2460 [-14 bytes / -0.57%] other/codesize/test_codesize_mem_O3_grow.jssize: 5172 => 5151 [-21 bytes / -0.41%] other/codesize/test_codesize_mem_O3_grow_standalone.gzsize: 2175 => 2169 [-6 bytes / -0.28%] other/codesize/test_codesize_mem_O3_grow_standalone.jssize: 4581 => 4571 [-10 bytes / -0.22%] other/codesize/test_codesize_mem_O3_standalone.gzsize: 2141 => 2133 [-8 bytes / -0.37%] other/codesize/test_codesize_mem_O3_standalone.jssize: 4513 => 4503 [-10 bytes / -0.22%] other/codesize/test_codesize_mem_O3_standalone_lib.gzsize: 1898 => 1891 [-7 bytes / -0.37%] other/codesize/test_codesize_mem_O3_standalone_lib.jssize: 4043 => 4033 [-10 bytes / -0.25%] other/codesize/test_codesize_mem_O3_standalone_narg.gzsize: 1912 => 1907 [-5 bytes / -0.26%] other/codesize/test_codesize_mem_O3_standalone_narg.jssize: 4044 => 4034 [-10 bytes / -0.25%] other/codesize/test_codesize_mem_O3_standalone_narg_flto.gzsize: 1912 => 1907 [-5 bytes / -0.26%] other/codesize/test_codesize_mem_O3_standalone_narg_flto.jssize: 4044 => 4034 [-10 bytes / -0.25%] other/codesize/test_codesize_minimal_64.gzsize: 1441 => 1425 [-16 bytes / -1.11%] other/codesize/test_codesize_minimal_64.jssize: 3058 => 3011 [-47 bytes / -1.54%] other/codesize/test_codesize_minimal_O0.gzsize: 6449 => 6440 [-9 bytes / -0.14%] other/codesize/test_codesize_minimal_O0.jssize: 17094 => 16995 [-99 bytes / -0.58%] other/codesize/test_codesize_minimal_O1.gzsize: 1534 => 1518 [-16 bytes / -1.04%] other/codesize/test_codesize_minimal_O1.jssize: 3702 => 3615 [-87 bytes / -2.35%] other/codesize/test_codesize_minimal_O2.gzsize: 1380 => 1366 [-14 bytes / -1.01%] other/codesize/test_codesize_minimal_O2.jssize: 2806 => 2759 [-47 bytes / -1.67%] other/codesize/test_codesize_minimal_O3.gzsize: 1347 => 1332 [-15 bytes / -1.11%] other/codesize/test_codesize_minimal_O3.jssize: 2756 => 2709 [-47 bytes / -1.71%] other/codesize/test_codesize_minimal_Os.gzsize: 1347 => 1332 [-15 bytes / -1.11%] other/codesize/test_codesize_minimal_Os.jssize: 2756 => 2709 [-47 bytes / -1.71%] other/codesize/test_codesize_minimal_Oz-ctors.gzsize: 1338 => 1326 [-12 bytes / -0.90%] other/codesize/test_codesize_minimal_Oz-ctors.jssize: 2741 => 2704 [-37 bytes / -1.35%] other/codesize/test_codesize_minimal_Oz.gzsize: 1347 => 1332 [-15 bytes / -1.11%] other/codesize/test_codesize_minimal_Oz.jssize: 2756 => 2709 [-47 bytes / -1.71%] other/codesize/test_codesize_minimal_esm.gzsize: 1542 => 1526 [-16 bytes / -1.04%] other/codesize/test_codesize_minimal_esm.jssize: 3210 => 3164 [-46 bytes / -1.43%] other/codesize/test_codesize_minimal_pthreads.gzsize: 4186 => 4185 [-1 bytes / -0.02%] other/codesize/test_codesize_minimal_pthreads.jssize: 8728 => 8754 [+26 bytes / +0.30%] other/codesize/test_codesize_minimal_wasmfs.gzsize: 1347 => 1332 [-15 bytes / -1.11%] other/codesize/test_codesize_minimal_wasmfs.jssize: 2756 => 2709 [-47 bytes / -1.71%] other/test_INCOMING_MODULE_JS_API.js.size: 3733 => 3748 [+15 bytes / +0.40%] other/test_unoptimized_code_size.js.size: 52739 => 52595 [-144 bytes / -0.27%] other/test_unoptimized_code_size.wasm.size: 15101 => 15110 [+9 bytes / +0.06%] other/test_unoptimized_code_size_no_asserts.js.size: 28487 => 28327 [-160 bytes / -0.56%] other/test_unoptimized_code_size_no_asserts.wasm.size: 12182 => 12194 [+12 bytes / +0.10%] other/test_unoptimized_code_size_strict.js.size: 51522 => 51378 [-144 bytes / -0.28%] other/test_unoptimized_code_size_strict.wasm.size: 15101 => 15110 [+9 bytes / +0.06%] Average change: -0.43% (-2.35% - +0.40%) ```

brendandahl · 2025-01-16T18:43:15Z

src/library.js

@@ -2296,6 +2296,16 @@ addToLibrary({

  $noExitRuntime: "{{{ makeModuleReceiveExpr('noExitRuntime', !EXIT_RUNTIME) }}}",

+  // functions called during startup


TODO: add changelog.

brendandahl · 2025-01-16T21:12:15Z

I've got an issue with pthreads ordering. __wasm_call_ctors needs to happen after some calls, but before other addOnInit code is run. Hmm...

sbc100 · 2025-01-16T21:51:44Z

src/library.js

@@ -2296,6 +2296,16 @@ addToLibrary({

  $noExitRuntime: "{{{ makeModuleReceiveExpr('noExitRuntime', !EXIT_RUNTIME) }}}",

+  // functions called during startup
+  $__ATINIT__: [],
+  $__ATINIT____postset: () => {


I keep forgetting that __postset can be a function...

sbc100 · 2025-01-16T21:53:42Z

tools/link.py

@@ -701,6 +701,7 @@ def phase_linker_setup(options, state):  # noqa: C901, PLR0912, PLR0915
      exit_with_error('PTHREADS_PROFILING only works with ASSERTIONS enabled')
    options.post_js.append(utils.path_from_root('src/threadprofiler.js'))
    settings.REQUIRED_EXPORTS.append('emscripten_main_runtime_thread_id')
+    settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += ['$addOnInit']


Why this? Maybe worth a comment?

sbc100 · 2025-01-16T21:53:53Z

tools/webidl_binder.py

@@ -97,7 +97,7 @@ def getExtendedAttribute(self, _name):
 #include <emscripten.h>
 #include <stdlib.h>

-EM_JS_DEPS(webidl_binder, "$intArrayFromString,$UTF8ToString,$alignMemory");
+EM_JS_DEPS(webidl_binder, "$intArrayFromString,$UTF8ToString,$alignMemory,$addOnInit");


Why this? I guess because the generated code uses addOnInit?

sbc100 · 2025-01-16T21:55:28Z

src/parseTools.mjs

@@ -709,7 +709,7 @@ export const ATMAINS = [];
 export const ATINITS = [];

 function addAtInit(code) {
-  ATINITS.push(code);
+  ATINITS.unshift(code);


Why this change?

sbc100 · 2025-01-16T21:56:36Z

src/library.js

@@ -2296,6 +2296,16 @@ addToLibrary({

  $noExitRuntime: "{{{ makeModuleReceiveExpr('noExitRuntime', !EXIT_RUNTIME) }}}",

+  // functions called during startup


Perhaps this comment could be a little more descriptive? I'm not sure if this is correct but maybe "Function the are called once the runtime is initialized and static constructors have been called".

sbc100

I like the idea in general!

brendandahl added 2 commits January 16, 2025 18:33

brendandahl commented Jan 16, 2025

View reviewed changes

brendandahl marked this pull request as draft January 16, 2025 21:10

sbc100 reviewed Jan 16, 2025

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Move addOnInit and ATINIT into a JS library. #23433

Move addOnInit and ATINIT into a JS library. #23433

brendandahl commented Jan 16, 2025 •

edited by sbc100

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brendandahl commented Jan 16, 2025

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		@@ -2296,6 +2296,16 @@ addToLibrary({

		$noExitRuntime: "{{{ makeModuleReceiveExpr('noExitRuntime', !EXIT_RUNTIME) }}}",

		// functions called during startup

Move addOnInit and __ATINIT__ into a JS library. #23433

Are you sure you want to change the base?

Move addOnInit and __ATINIT__ into a JS library. #23433

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Move addOnInit and ATINIT into a JS library. #23433

Move addOnInit and ATINIT into a JS library. #23433

brendandahl commented Jan 16, 2025 •

edited by sbc100

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