On Wed, 22 Feb 2023 07:11:16 GMT, Eirik Bjorsnos <d...@openjdk.org> wrote:
>> This PR suggests we can speed up `StringLatin1.regionMatchesCI` by applying
>> 'the oldest ASCII trick in the book'.
>>
>> The new static method `CharacterDataLatin1.equalsIgnoreCase` compares two
>> latin1 bytes for equality ignoring case. `StringLatin1.regionMatchesCI` is
>> updated to use `equalsIgnoreCase`
>>
>> To verify the correctness of `equalsIgnoreCase`, a new test is added to
>> `EqualsIgnoreCase` with an exhaustive verification that all 256x256 latin1
>> code point pairs have an `equalsIgnoreCase` consistent with
>> Character.toUpperCase, Character.toLowerCase.
>>
>> Performance is tested for matching and mismatching cases of code point pairs
>> picked from the ASCII letter, ASCII number and latin1 letter ranges. Results
>> in the first comment below.
>
> Eirik Bjorsnos has updated the pull request incrementally with two additional
> commits since the last revision:
>
> - Replace 'oldest ASCII trick in the book' use in toUpperCase, toLowerCase
> with "by removing (setting) a single bit"
> - Align local variable naming in toLowerCase, toUpperCase with
> equalsIgnoreCase by using 'lower' and 'upper'
Marked as reviewed by martin (Reviewer).
test/jdk/java/lang/String/CompactString/EqualsIgnoreCase.java line 89:
> 87: for (int ab = 0; ab < 256; ab++) {
> 88: for (int bb = 0; bb < 256; bb++) {
> 89: char a = (char) ab, b = (char) bb;
char is an unsigned numeric type, so cleaner is
for (char a = 0; a < 256; a++)
for (char b = 0; b < 256; b++)
-------------
PR: https://git.openjdk.org/jdk/pull/12632
