tree 9435898da93bfa096779a155c81a32acaed3f16d
parent 63d8015eb823e14eb3184232334cf911e5625815
author Alan Donovan <adonovan@google.com> 1655147372 -0400
committer Alan Donovan <adonovan@google.com> 1655865454 +0000

internal/span: optimise URI.Filename to avoid allocation

This change adds a fast-path check for the common case:
"file:", lowercase, followed by a simple POSIX absolute
file name without special characters.

This function used to account for 1% of CPU on the DidChange
benchmark (and I'm sure I've seen higher fractions on other
tests--but perhaps that was before the clone optimizations?).

It was tested by adding an assertion that it agrees with the
slow path and running all our tests.

Change-Id: I15492b8a317715468870b00041bf8f6b0bb53bb2
Reviewed-on: https://go-review.googlesource.com/c/tools/+/411900
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Run-TryBot: Alan Donovan <adonovan@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>