minifier: milestone 2

[Boshen]

• mangleStmts https://github.com/evanw/esbuild/blob/v0.24.2/internal/js_parser/js_parser.go#L8788
• MangleIfExpr https://github.com/evanw/esbuild/blob/v0.24.2/internal/js_ast/js_ast_helpers.go#L2745
• SimplifyBooleanExpr
  https://github.com/evanw/esbuild/blob/v0.24.2/internal/js_ast/js_ast_helpers.go#L2745
• Remove Inlined Constants:
  • TODO
  • evanw/esbuild@1d7fc14#diff-e20508c4ae566a2d8a60274ff05e408d81c9758a27d84318feecdfbf9e24af5e
• Control Flow Optimization:
  • Done:

    oxc/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs

    Line 76 in 6c7acac

    fn dead_code_elimination(&mut self, stmts: &mut Vec<'a, Statement<'a>>, ctx: Ctx<'a, 'b>) {

• Variable Inlining:
  • TODO
• Statement Merging:
  • Done:

    oxc/crates/oxc_minifier/src/ast_passes/statement_fusion.rs

    Line 36 in 772b71c

    fn fuse_statements(&mut self, stmts: &mut Vec<'a, Statement<'a>>, ctx: &mut TraverseCtx<'a>) {

• Control Flow Simplification:
  • initial impl done, but buggy: refactor(minifier): remove the buggy minimize_exit_points implementation #8349
• Trailing Jump Optimization:
  • TODO: continue/return/break stmts at the end of control flow are dropped
• Try-Catch Simplification:
  • Done

    oxc/crates/oxc_minifier/src/ast_passes/peephole_substitute_alternate_syntax.rs

    Line 191 in 772b71c

    fn compress_catch_clause(&mut self, catch: &mut CatchClause<'_>, ctx: &mut TraverseCtx<'a>) {

• Switch and For Loop Transformations:
  • TODO

Originally posted by @camc314 in #8264 (comment)

[Boshen]

Had a quick look at https://github.com/tdewolff/minify, it produces slightly better minification due to

• var hoisting
• remove unused function parameters

[Boshen]

Enabling the mangler in test262 reveals the need of

• --keep-names https://esbuild.github.io/api/#keep-names
• bail eval https://esbuild.github.io/content-types/#direct-eval

[Boshen]

I'm going to clear #8604 and then overhaul the current architecture for performance, the minifier is running too slow for my likings.

[Boshen]

Latest benchmark shows really promising results https://github.com/privatenumber/minification-benchmarks

[benmccann]

Do you think we could reopen #2646? It was previously closed since the minifier wasn't being worked on, but it looks like perhaps that's no longer the case?

[Boshen]

Also:

• pure annotations https://github.com/javascript-compiler-hints/compiler-notations-spec

[Boshen]

Moving rest of the todos to milestone 3. Time to stabilize for an alpha version.