Changed the mangler to reuse variable names where possible.
This will reduce the code size as shorter variable names can be used in
more places. But requires global information and limits parallelism in a
single file and requires more memory.
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Co-authored-by: Boshen <boshenc@gmail.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Adds `top_level` option which is similar to [terser's `toplevel`
option](https://terser.org/docs/cli-usage/#cli-mangle-options).
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Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
After studying google closure compiler, I'm leaning towards a multi-ast-pass infrastructure for the minifier.
This is one of the few places where we are going to trade maintainability over performance, given the goal of the minifier is compression size not performance.
All of the terminologies and separation of concerns are aligned with google closure compiler.
Infrastructure of `terser` and `esbuild` are not suitable for us to study nor pursuit. Their code are so tightly coupled - I failed to comprehend any of them every time I try to walk through a piece of optmization. Google closure compiler despite being written in Java, it's actually the most readable minifier out there.
To improve performance between ast passes, I envision a change detection system over a portion of the code.
The benchmark will demonstrate the performance regression of running 5 ast passes instead of 2.
To complete this PR, I need to figure out "fix-point" and order of these ast passes.
