Performance degradation after turning on new tree shaking

[chenjiahan]

System Info

@rspack/core: 0.4.5

System:
OS: macOS 13.5.2
CPU: (10) arm64 Apple M1 Pro
Memory: 1.69 GB / 32.00 GB
Shell: 5.9 - /bin/zsh
Binaries:
npm: 9.3.1 - ~/Library/Application Support/fnm/node-versions/v18.14.1/installation/bin/npm
pnpm: 8.8.0 - ~/Library/Application Support/fnm/node-versions/v18.14.1/installation/bin/pnpm
Browsers:
Chrome: 120.0.6099.129
Safari: 16.6

Details

I have tried to enable tree shaking in the Vant website, and found that the compile time increased from 3s to 23s.

• newTreeshaing: false:

• newTreeshaing: true:

Reproduce link

https://github.com/youzan/vant/tree/new_tree_shaking_1226

Reproduce Steps

Enable new tree shaking:

1. git clone git@github.com:youzan/vant.git --branch new_tree_shaking_1226
2. pnpm i
3. pnpm dev

Disable new tree shaking:

1. search newTreeshaking: true, change the value to false.
2. pnpm i (to trigger rebuild)
3. pnpm dev

[IWANABETHATGUY]

I think we should compare the speed between production, since if you open newTreeshaking rspack will execute flagDepenencyExports and rspack will do nothing if you disable it.

[IWANABETHATGUY]

Still it should not take so long.

[chenjiahan]

The performance of the production build is not affected, but I am quite curious as to why there is such a significant regression in the dev performance.

Maybe there is some performance issue with flagDepenencyExports?

[IWANABETHATGUY]

exports_info_hash almost cost 10s, why do we need to hash the whole ExportsInfo struct instead of a UniqueId?
cc @LingyuCoder

[IWANABETHATGUY]

see #5125