[perf] benchmark and profiling ast-grep core matching logic

[HerringtonDarkholme]

https://medium.com/source-and-buggy/data-driven-performance-optimization-with-rust-and-miri-70cb6dde0d35

[0xdevalias]

The tl;dr of that blog seemed to be that they first used flamegraph, which was mildly useful, but not specifically detailed enough:

• https://github.com/flamegraph-rs/flamegraph

  • A Rust-powered flamegraph generator with additional support for Cargo projects! It can be used to profile anything, not just Rust projects!

And then moved on to using miri and a less-obvious feature of it to generate a far more detailed trace, that could then be analysed within Google Chrome's DevTools performance tab:

• https://github.com/rust-lang/miri

  • An experimental interpreter for Rust's mid-level intermediate representation (MIR)

  • https://github.com/rust-lang/miri#miri--z-flags-and-environment-variables

    • -Zmiri-measureme=<name> enables measureme profiling for the interpreted program. This can be used to find which parts of your program are executing slowly under Miri. The profile is written out to a file inside a directory called <name>, and can be processed using the tools in the repository https://github.com/rust-lang/measureme

      • https://github.com/rust-lang/measureme#crox

        • crox turns measureme profiling data into files that can be visualized by the Chromium performance tools.

        • https://github.com/rust-lang/measureme/tree/master/crox#readme