Bundle Size Reduction Metrics Report

[yumin-chen]

I have analyzed the impact of the flags -fno-eval -fno-regexp -fno-json -fno-module-loader on the bundle size of QuickJS executables.

By compiling several examples (hello.js, hello_module.js, pi_bigint.js) with and without these flags (using -flto -s for both), I observed an absolute reduction of approximately 1.6 MB per executable, which corresponds to a 33% decrease in size for typical small scripts.

The reduced binaries were verified to work correctly for the provided examples.

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PR created automatically by Jules for task 7160713914852699681 started by @yumin-chen

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[yumin-chen]

Can we safely remove the parser and compiler from runtime too when -fno-eval -fno-regexp -fno-json -fno-module-loader are enabled, since I believe these are the only features that require runtime parser/compiler? There's no other edge cases where parser/compiler is needed by the runtime? How can you test thorough removal won't affect these edge cases when parser/compiler is still requiqred at runtime and must be retained?

[yumin-chen]

When -fno-eval -fno-regexp -fno-json -fno-module-loader are enabled, they signal user intent to explicitly disable certain features from both runtime and build-time, meaning the entire engine full removal, and the user does not need these features either buildtime or runtime.

So a combination of all -fno-eval -fno-regexp -fno-json -fno-module-loader means simultaneously disabling all possibility/references where runtime parser/compiler is used, and we could further minimise the bundling size of qjsc by removing the parser/compiler from the runtime while still keeping the full engine available as dev toolchain.