path/filepath: optimize isReservedName

A linear search through a list of 22 strings takes ~80ns.
A quick check for 3-4 byte strings reduces this check to 2ns
for a vast majority of inputs.
In the event of a name match, the new logic is either just
as fast (for "CON") or 10x faster (for "LPT9").

Change-Id: I412fa73beebd7c81dc95f9ed12c35ca1d5d6baf0
Reviewed-by: Damien Neil <>
Run-TryBot: Joseph Tsai <>
TryBot-Result: Gopher Robot <>
Auto-Submit: Joseph Tsai <>
Reviewed-by: Ian Lance Taylor <>
1 file changed
tree: 19c7efe7b981bfaa81d0180cdd94bb1196b03bf5
  1. .github/
  2. api/
  3. doc/
  4. lib/
  5. misc/
  6. src/
  7. test/
  8. .gitattributes
  9. .gitignore
  10. codereview.cfg

The Go Programming Language

Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.

Gopher image Gopher image by Renee French, licensed under Creative Commons 3.0 Attributions license.

Our canonical Git repository is located at There is a mirror of the repository at

Unless otherwise noted, the Go source files are distributed under the BSD-style license found in the LICENSE file.

Download and Install

Binary Distributions

Official binary distributions are available at

After downloading a binary release, visit for installation instructions.

Install From Source

If a binary distribution is not available for your combination of operating system and architecture, visit for source installation instructions.


Go is the work of thousands of contributors. We appreciate your help!

To contribute, please read the contribution guidelines at

Note that the Go project uses the issue tracker for bug reports and proposals only. See for a list of places to ask questions about the Go language.