Performance issues with short bytestring's 'unpack'

In GitLab by @maerwald on Jul 17, 2022, 20:37

https://github.com/haskell/bytestring/pull/526

Benchmark comparison: https://gist.github.com/hasufell/cb46c979fedcef8a5d087ad193666e74

## Regressions

* replaceFileName (windows)
* dropFileName (windows)
* takeDirectory (windows)
* combine (windows)
* joinPath (windows)
* splitDirectories (windows)
* splitDrive (windows)
* takeDrive (windows)
* hasDrive (posix)
* hasDrive (windows)
* dropDrive (windows)
* isDrive (posix)
* isDrive (windows)
* normalise (windows)
* equalFilePath (windows)
* makeRelative (windows)
* isRelative (posix)
* isRelative (windows)
* isAbsolute (posix)
* isAbsolute (windows)
* isValid (windows)
* makeValid (windows)

## Improvements

* splitExtension (posix)
* splitExtension (windows)
* takeExtension (posix)
* takeExtension (windows)
* replaceExtension (posix)
* replaceExtension (windows)
* dropExtension (posix)
* dropExtension (windows)
* addExtension (posix)
* addExtension (windows)
* hasExtension (posix)
* hasExtension (windows)
* splitExtensions (posix)
* splitExtensions (windows)
* dropExtensions (posix)
* dropExtensions (windows)
* takeExtensions (posix)
* takeExtensions (windows)
* replaceExtensions (posix)
* replaceExtensions (windows)
* isExtensionOf (posix)
* isExtensionOf (windows)
* stripExtension (posix)
* stripExtension (windows)
* splitFileName (posix)
* splitFileName (windows)
* takeFileName (posix)
* takeFileName (windows)
* replaceFileName (posix)
* dropFileName (posix)
* takeBaseName (posix)
* takeBaseName (windows)
* replaceBaseName (posix)
* replaceBaseName (windows)
* takeDirectory (posix)
* replaceDirectory (posix)
* replaceDirectory (windows)
* combine (posix)
* splitPath (posix)
* splitPath (windows)
* joinPath (posix)
* splitDirectories (posix)
* splitDrive (posix)
* joinDrive (posix)
* joinDrive (windows)
* takeDrive (posix)
* dropDrive (posix)
* hasTrailingPathSeparator (posix)
* hasTrailingPathSeparator (windows)
* addTrailingPathSeparator (posix)
* addTrailingPathSeparator (windows)
* dropTrailingPathSeparator (posix)
* dropTrailingPathSeparator (windows)
* normalise (posix)
* equalFilePath (posix)
* makeRelative (posix)
* isValid (posix)
* makeValid (posix)
* splitSearchPath (posix)
* splitSearchPath (windows)

Start with the linked bytestring pull request and the benchmark comparison, then review the listed filepath regressions and improvements. The issue does not name files or tests; completion would require resolving the short-bytestring unpack performance concern while preserving the reported platform-specific behavior.

Written by the indexing model from the issue text.