Bug 246009

Created attachment 462781 [details] Launch_bun_2022-10-03_23.22.34_2576143F.trace.zip I've attached an Instruments trace and sampling profiler output of using Rollup.js to bundle the "@babel/standalone" npm package. End-to-end, it runs about 1.6x slower in JSC (bun) compared to V8 (node). Nearly all the time is spent in JSC. I think it's _mostly_ because of Object.entries() (which is why the issue is titled about Object.entries()). Rollup seems to use Object.entries() in their code a _lot_. In @babel/standalone's case, Object.entries() is called 550,000 times. For larger objects, Object.entries() is around 1.5x slower than in V8 (microbenchmark). It looks like ObjectKeys exists in DFGSpeculateJIT64.cpp but ObjectEntries and ObjectValues do not. Maybe adding it as a JIT operation would help? I don't know if that's the whole story though. It feels like there's a side effects tracking thing that would enable skipping some of the PropertyTable::find lookups, maybe? ``` ❯ bun /Users/jarred/Code/bun/bench/snippets/object-entries.mjs cpu: Apple M1 Max runtime: bun 0.1.14 (arm64-darwin) benchmark time (avg) (min … max) p75 p99 p995 --------------------------------------------------------------- ----------------------------- Object.entries(26 keys) 1.27 µs/iter (1.21 µs … 1.99 µs) 1.28 µs 1.99 µs 1.99 µs Object.keys(26 keys) 515.77 ns/iter (477.57 ns … 628.68 ns) 526.63 ns 617.05 ns 628.68 ns Object.entries(2 keys) 132.46 ns/iter (125.25 ns … 205.22 ns) 127.54 ns 194.48 ns 196.87 ns Object.keys(2 keys) 4.68 ns/iter (4.12 ns … 219.59 ns) 4.42 ns 7.48 ns 10.22 ns ``` ``` ❯ node /Users/jarred/Code/bun/bench/snippets/object-entries.mjs cpu: Apple M1 Max runtime: node v18.9.1 (arm64-darwin) benchmark time (avg) (min … max) p75 p99 p995 --------------------------------------------------------------- ----------------------------- Object.entries(26 keys) 830.02 ns/iter (803.19 ns … 1.07 µs) 821.85 ns 1.07 µs 1.07 µs Object.keys(26 keys) 327.72 ns/iter (319.58 ns … 421.81 ns) 329.03 ns 400.85 ns 421.81 ns Object.entries(2 keys) 98.28 ns/iter (96.05 ns … 452.63 ns) 97.19 ns 105.5 ns 108.87 ns Object.keys(2 keys) 13.36 ns/iter (10.75 ns … 76.29 ns) 15.3 ns 17.92 ns 21.13 ns ``` - Benchmark: ``` import { bench, run } from "../../node_modules/mitata/src/cli.mjs"; const obj = { a: 1, b: 2, c: 3, d: 4, e: 5, f: 6, g: 7, h: 8, i: 9, j: 10, k: 11, l: 12, m: 13, n: 14, o: 15, p: 16, q: 17, r: 18, s: 19, t: 20, u: 21, v: 22, w: 23, x: 24, y: 25, z: 26, }; bench("Object.entries(26 keys)", () => { var k; for (let [key, value] of Object.entries(obj)) { value = key; } return k; }); bench("Object.keys(26 keys)", () => { var k; for (let [key, value] of Object.keys(obj)) { value = key; } return k; }); bench("Object.entries(2 keys)", () => { var k; for (let [key, value] of Object.entries({ a: 1, b: 2 })) { value = key; } return k; }); bench("Object.keys(2 keys)", () => { var k; for (let item of Object.keys({ a: 1, b: 2 })) { } return k; }); await run(); ``` Sampling profiler output: Sampling rate: 100.000000 microseconds. Total samples: 19077 Top functions as <numSamples 'functionName#hash:sourceID'> 4028 'include#<nil>:5' 1552 'parseNode#<nil>:5' 1299 '#<nil>:5' 1089 'entries#<nil>:4294967295' 979 'includeCallArguments#<nil>:5' 809 'create#<nil>:4294967295' 656 'hasEffects#<nil>:5' 606 'arrayIteratorNextHelper#<nil>:7' 568 'NodeBase#<nil>:5' 547 '#<nil>:4294967295' 506 'bind#<nil>:5' 495 'render#<nil>:5' Sampling rate: 100.000000 microseconds. Total samples: 19077 Tier breakdown: ----------------------------------- LLInt: 184 (0.964512%) Baseline: 935 (4.901190%) DFG: 3991 (20.920480%) FTL: 10469 (54.877601%) js builtin: 862 (4.518530%) Wasm: 0 (0.000000%) Host: 559 (2.930230%) RegExp: 115 (0.602820%) C/C++: 0 (0.000000%) Unknown Frame: 4 (0.020968%) Unknown Executable: 2820 (14.782198%) Hottest bytecodes as <numSamples 'functionName#hash:JITType:bytecodeIndex'> 1089 'entries#<nil>:None:<nil>' 1001 'include#<nil>:FTL:bc#33' 809 'create#<nil>:None:<nil>' 575 'parseNode#<nil>:FTL:bc#218' 547 '#<nil>:None:<nil>' 443 'parseNode#<nil>:FTL:bc#479' 411 'Set#<nil>:None:<nil>' 404 'include#<nil>:FTL:bc#107' 363 'include#<nil>:FTL:bc#296' 337 'include#<nil>:FTL:bc#93' 280 'arrayIteratorNextHelper#<nil>:FTL:bc#122' 272 'include#<nil>:FTL:bc#54' 251 'arrayIteratorNextHelper#<nil>:FTL:bc#58' 221 'includeCallArguments#<nil>:FTL:bc#59' 206 'includeProperties#<nil>:FTL:bc#59' 127 'Map#<nil>:None:<nil>' 117 'getEntities#<nil>:FTL:bc#180' 111 'include#<nil>:FTL:bc#0' 107 'parseModule#<nil>:None:<nil>' 106 'values#<nil>:None:<nil>' 106 'parseNode#<nil>:FTL:bc#760' 95 'includeCallArguments#<nil>:DFG:bc#201' 90 'include#<nil>:FTL:bc#138' 87 'getEntities#<nil>:FTL:bc#76' 84 'includeCallArguments#<nil>:FTL:bc#0' 81 'bind#<nil>:FTL:bc#262' 81 'delete#<nil>:None:<nil>' 81 'include#<nil>:FTL:bc#196' 77 '#<nil>:FTL:bc#0' 75 'createScope#<nil>:FTL:bc#11' 73 'include#<nil>:FTL:bc#27' 73 'include#<nil>:FTL:<nil>' 72 '/^(?:break|case|catch|continue|debugger|default|do|else|finally|for|function|if|return|switch|throw|try|var|while|with|null|true|false|instanceof|typeof|void|delete|new|in|this|const|class|extends|export|import|super)$/#<nil>:RegExp:<nil>' 72 'bind#<nil>:FTL:bc#65' 71 'includeCallArguments#<nil>:FTL:<nil>' 71 'includeProperties#<nil>:FTL:bc#19' 70 'include#<nil>:DFG:bc#54' 66 'includeProperties#<nil>:FTL:bc#70' 65 'includeUnknownTest#<nil>:DFG:bc#22' 65 'include#<nil>:FTL:bc#229'