# \[Help wanted\]: SWIPL wasm build not compatible with emsdk v4

**URL:** <https://swi-prolog.discourse.group/t/help-wanted-swipl-wasm-build-not-compatible-with-emsdk-v4/8735>\
**Category:** General\
**Created:** [January 18, 2025, 11:26am UTC](https://swi-prolog.discourse.group/t/help-wanted-swipl-wasm-build-not-compatible-with-emsdk-v4/8735 "2025-01-18T11:26:16Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jeswr](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jeswr/32/5469_2.png) [@jeswr](https://swi-prolog.discourse.group/u/jeswr)\
**Post date:** [January 18, 2025, 11:26am UTC](https://swi-prolog.discourse.group/t/help-wanted-swipl-wasm-build-not-compatible-with-emsdk-v4/8735/1 "2025-01-18T11:26:16Z")

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Our CI in `swipl-wasm` is broken when trying to auto update to emsdk v4 [1]. Unfortunately, I do not have time to resolve this issue myself at present; so any support in resolving this issue will be greatly appreciated.

Note the fix will need to be upstream in the swipl-devel repo [2].

[1] [BREAKING CHANGE: update to emsdk v4.0.1 by jeswr · Pull Request #840 · SWI-Prolog/npm-swipl-wasm · GitHub](https://github.com/SWI-Prolog/npm-swipl-wasm/pull/840#issuecomment-2599666979)  
[2] [wasm build incompatible with emsdk v4 · Issue #1343 · SWI-Prolog/swipl-devel · GitHub](https://github.com/SWI-Prolog/swipl-devel/issues/1343)

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**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\
**Post date:** [January 30, 2025, 7:38pm UTC](https://swi-prolog.discourse.group/t/help-wanted-swipl-wasm-build-not-compatible-with-emsdk-v4/8735/2 "2025-01-30T19:38:39Z")

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The issue has been fixed in the GIT version. But … running the benchmarks using `node` shows a slowdown of approximately 3 times ☹ Does anyone know why Emscripten 4 is so much slower than 3?

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**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\
**Post date:** [January 31, 2025, 8:31am UTC](https://swi-prolog.discourse.group/t/help-wanted-swipl-wasm-build-not-compatible-with-emsdk-v4/8735/3 "2025-01-31T08:31:01Z")

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Oops. The Emscripted `-sASSERTIONS` was still in effect. Emscripten 4 performance is the same as the latest Emscripten 3 release. Sorry for the noise.