swc/crates/swc_ecma_preset_env/benches/polyfills.rs

use criterion::{black_box, criterion_group, criterion_main, Bencher, Criterion};
use swc_common::{comments::SingleThreadedComments, FileName, Mark};
use swc_ecma_parser::{Parser, StringInput, Syntax};
use swc_ecma_preset_env::{preset_env, Config};
use swc_ecma_visit::FoldWith;

fn run(b: &mut Bencher, src: &str, config: Config) {
    let _ = ::testing::run_test(false, |cm, handler| {
        let fm = cm.new_source_file(FileName::Anon, src.into());

        let mut parser = Parser::new(Syntax::default(), StringInput::from(&*fm), None);
        let module = parser
            .parse_module()
            .map_err(|e| e.into_diagnostic(handler).emit())
            .unwrap();

        for e in parser.take_errors() {
            e.into_diagnostic(handler).emit()
        }

        let mut folder = preset_env(
            Mark::fresh(Mark::root()),
            Some(SingleThreadedComments::default()),
            config,
            Default::default(),
        );

        b.iter(|| black_box(module.clone().fold_with(&mut folder)));
        Ok(())
    });
}

fn bench_cases(c: &mut Criterion) {
    c.bench_function("es/preset-env/usage/builtin_type", |b| {
        const SOURCE: &str = r#"
        // From a length
        var float32 = new Float32Array(2);
        float32[0] = 42;
        console.log(float32[0]); // 42
        console.log(float32.length); // 2
        console.log(float32.BYTES_PER_ELEMENT); // 4
        
        // From an array
        var arr = new Float32Array([21,31]);
        console.log(arr[1]); // 31
        
        // From another TypedArray
        var x = new Float32Array([21, 31]);
        var y = new Float32Array(x);
        console.log(y[0]); // 21
        
        // From an ArrayBuffer
        var buffer = new ArrayBuffer(16);
        var z = new Float32Array(buffer, 0, 4);
        
        // From an iterable
        var iterable = function*(){ yield* [1,2,3]; }();
        var float32 = new Float32Array(iterable);
        // Float32Array[1, 2, 3]
        "#;

        run(b, SOURCE, Default::default())
    });

    c.bench_function("es/preset-env/usage/property", |b| {
        const SOURCE: &str = r#"
        const target = { a: 1, b: 2 };
        const source = { b: 4, c: 5 };
        
        const returnedTarget = Object.assign(target, source);
        
        console.log(target);
        // expected output: Object { a: 1, b: 4, c: 5 }
        
        console.log(returnedTarget);
        // expected output: Object { a: 1, b: 4, c: 5 }
        "#;

        run(b, SOURCE, Default::default())
    });
}

criterion_group!(benches, bench_cases);
criterion_main!(benches);