regexp/syntax: test for lowercase letters first in IsWordChar
Lowercase letters occur more frequently than uppercase letters
in English text. In IsWordChar, evaluate the most common case
(lowercase letters) first to minimize the expected value of its
execution time. Code clarity does not suffer by rearranging the
order of the checks.
Add a benchmark on a sentence demonstrating the performance
improvement.
name old time/op new time/op delta
IsWordChar-10 122ns ± 0% 114ns ± 1% -6.68% (p=0.000 n=8+10)
Change-Id: Ieee8126a4bd8ee8703905b4f75724623029f6fa2
Reviewed-on: https://go-review.googlesource.com/c/go/+/404100 Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com> Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
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