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https://github.com/oven-sh/bun
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## Summary
Optimize `path.parse()` by caching a pre-built JSC Structure for the
result object. Instead of creating a new empty object and performing 5
`putDirect` calls (each triggering a Structure transition), we now use
`constructEmptyObject` with the cached Structure and write values
directly via `putDirectOffset`.
## What changed
- **`ZigGlobalObject.h/cpp`**: Added `m_pathParsedObjectStructure` as a
`LazyPropertyOfGlobalObject<Structure>` with fixed property offsets for
`{root, dir, base, ext, name}`.
- **`Path.cpp`**: Added `PathParsedObject__create` extern "C" factory
function that constructs the object using the pre-built Structure and
`putDirectOffset`.
- **`path.zig`**: Replaced `toJSObject()` implementation to call the C++
factory function instead of `createEmptyObject` + 5x `.put()`.
- **`bench/snippets/path-parse.mjs`**: Added benchmark for
`path.parse()`.
This follows the same pattern used by `JSSocketAddressDTO` and
`m_jsonlParseResultStructure`.
## Benchmark results (Apple M4 Max)
| Benchmark | Before (1.3.9) | After | Speedup |
|---|---|---|---|
| `posix.parse("/home/user/dir/file.txt")` | 266.71 ns | 119.62 ns |
**2.23x** |
| `posix.parse("/home/user/dir/")` | 239.10 ns | 91.46 ns | **2.61x** |
| `posix.parse("file.txt")` | 232.55 ns | 89.20 ns | **2.61x** |
| `posix.parse("/root")` | 246.75 ns | 92.68 ns | **2.66x** |
| `posix.parse("")` | 152.19 ns | 20.72 ns | **7.34x** |
| `win32.parse("/home/user/dir/file.txt")` | 260.08 ns | 118.12 ns |
**2.20x** |
| `win32.parse("/home/user/dir/")` | 234.35 ns | 93.47 ns | **2.51x** |
| `win32.parse("file.txt")` | 224.19 ns | 80.56 ns | **2.78x** |
| `win32.parse("/root")` | 241.20 ns | 88.23 ns | **2.73x** |
| `win32.parse("")` | 160.39 ns | 24.20 ns | **6.63x** |
**~2.2x–2.8x faster** for typical paths, **~7x faster** for empty
strings.
## GC Safety
- `LazyPropertyOfGlobalObject<Structure>` is automatically visited via
`FOR_EACH_GLOBALOBJECT_GC_MEMBER`.
- JSValues created by `createUTF8ForJS` are protected by JSC's
conservative stack scanning during the factory function call.
## Test
All 116 existing path tests pass (`bun bd test test/js/node/path/`).
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
npm install
bun run ffi
bun run log
bun run gzip
bun run async
bun run sqlite
# to use custom version of bun/deno/node binary
BUN=path/to/bun bun run ffi
# or edit .env file