| Summary: | [JSC] Optimize String#substring | ||
|---|---|---|---|
| Product: | WebKit | Reporter: | Jarred Sumner <jarred> |
| Component: | JavaScriptCore | Assignee: | Yusuke Suzuki <ysuzuki> |
| Status: | RESOLVED FIXED | ||
| Severity: | Normal | CC: | mark.lam, webkit-bug-importer, ysuzuki |
| Priority: | P2 | Keywords: | InRadar |
| Version: | WebKit Nightly Build | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
startsWith and indexOf are already nice. I think we should handle substring, substr, slice in DFG to avoid type check for double / int32 etc. And some case, we should do constant folding. Pull request: https://github.com/WebKit/WebKit/pull/4844 cpu: unknown runtime: unknown (unknown) benchmark time (avg) (min … max) p75 p99 p995 ----------------------------------------------------------------------------------- ----------------------------- startsWith 9.41 ns/iter (9.28 ns … 18.68 ns) 9.32 ns 11.2 ns 11.49 ns prototype_startsWith 12.09 ns/iter (4.33 ns … 89.69 ns) 15.72 ns 18.61 ns 21.42 ns _startsWith 5.09 ns/iter (4.33 ns … 12.08 ns) 5.13 ns 5.66 ns 9.95 ns substring(0,8) 8.48 ns/iter (8.4 ns … 10.31 ns) 8.45 ns 8.93 ns 9.05 ns substring(0, length) === (substr strict) 8.5 ns/iter (8.4 ns … 10.47 ns) 8.46 ns 8.99 ns 9.07 ns substring(0, length) == (substr non-strict) 8.81 ns/iter (8.71 ns … 10.49 ns) 8.77 ns 9.3 ns 9.38 ns indexOf strict 18.12 ns/iter (17.99 ns … 20.33 ns) 18.29 ns 18.79 ns 19.03 ns indexOf non-strict 18.14 ns/iter (17.99 ns … 21 ns) 18.3 ns 18.98 ns 19.18 ns Committed 255030@main (3de7e6fba239): <https://commits.webkit.org/255030@main> Reviewed commits have been landed. Closing PR #4844 and removing active labels. |
❯ jsc foo.mjs cpu: unknown runtime: unknown (unknown) benchmark time (avg) (min … max) p75 p99 p995 ----------------------------------------------------------------------------------- ----------------------------- startsWith 11 ns/iter (10.51 ns … 21.54 ns) 10.78 ns 15.12 ns 15.71 ns prototype_startsWith 34.36 ns/iter (32.08 ns … 150.64 ns) 34.63 ns 39.24 ns 80.12 ns _startsWith 38.76 ns/iter (36.85 ns … 124.11 ns) 39.07 ns 47.63 ns 81.98 ns substring(0,8) 36.64 ns/iter (34.45 ns … 148.93 ns) 37.06 ns 45.9 ns 74.68 ns substring(0, length) === (substr strict) 38.45 ns/iter (36.84 ns … 155.19 ns) 38.82 ns 47.86 ns 75.75 ns substring(0, length) == (substr non-strict) 38.76 ns/iter (36.8 ns … 130.45 ns) 39.1 ns 47.66 ns 69.83 ns indexOf strict 15.75 ns/iter (15.49 ns … 24.07 ns) 15.55 ns 17.25 ns 17.47 ns indexOf non-strict 13.67 ns/iter (13 ns … 18.34 ns) 14.52 ns 17.06 ns 17.14 ns ❯ node foo.mjs cpu: Apple M1 Max runtime: node v18.4.0 (arm64-darwin) benchmark time (avg) (min … max) p75 p99 p995 ----------------------------------------------------------------------------------- ----------------------------- startsWith 19.11 ns/iter (18.58 ns … 404.22 ns) 18.68 ns 23.09 ns 26.93 ns prototype_startsWith 16.19 ns/iter (14.25 ns … 28.51 ns) 17.43 ns 23.3 ns 24.11 ns _startsWith 16.14 ns/iter (14.55 ns … 285.63 ns) 16.8 ns 21.92 ns 22.95 ns substring(0,8) 15.94 ns/iter (14.25 ns … 48.39 ns) 16.06 ns 25.28 ns 28.27 ns substring(0, length) === (substr strict) 15.34 ns/iter (14.25 ns … 31.48 ns) 15.72 ns 22.83 ns 24.01 ns substring(0, length) == (substr non-strict) 15.87 ns/iter (14.25 ns … 31.93 ns) 15.82 ns 24.57 ns 25.63 ns indexOf strict 14.68 ns/iter (13.88 ns … 21.2 ns) 14.8 ns 16.66 ns 16.98 ns indexOf non-strict 14.62 ns/iter (14.29 ns … 18.91 ns) 14.46 ns 16.8 ns 17.02 ns Code: ``` import { run, bench, baseline } from "./node_modules/mitata/src/cli.mjs"; function _startsWith(str, find) { return str.substring(0,find.length) === find } String.prototype._startsWith = function (find) { return this.substring(0,find.length) === find } baseline("startsWith", () => "/assets/omfg".startsWith('/assets/')); baseline("prototype_startsWith", () => "/assets/omfg"._startsWith('/assets/')); baseline("_startsWith", () => _startsWith("/assets/omfg", '/assets/')); baseline("substring(0,8)", () => "/assets/omfg".substring(0,8) === '/assets/'); baseline("substring(0, length) === (substr strict)", () => "/assets/omfg".substring(0,'/assets/'.length) === '/assets/'); baseline("substring(0, length) == (substr non-strict)", () => "/assets/omfg".substring(0,'/assets/'.length) == '/assets/'); baseline("indexOf strict", () => "/assets/omfg".indexOf('/assets/') === 0); baseline("indexOf non-strict", () => "/assets/omfg".indexOf('/assets/') == 0); await run(); ```