On Wed, 8 Feb 2023 00:07:14 GMT, Claes Redestad <redes...@openjdk.org> wrote:
>> This patch adds special-cases to `Arrays.copyOf` and `Arrays.copyOfRange` to
>> clone arrays when `newLength` or range inputs span the input array. This
>> helps eliminate range checks and has been verified to help various String
>> operations. Example:
>>
>> Baseline
>>
>> Benchmark (size) Mode Cnt
>> Score Error Units
>> StringConstructor.newStringFromArray 7 avgt 15
>> 16.817 ± 0.369 ns/op
>> StringConstructor.newStringFromArrayWithCharset 7 avgt 15
>> 16.866 ± 0.449 ns/op
>> StringConstructor.newStringFromArrayWithCharsetName 7 avgt 15
>> 22.198 ± 0.396 ns/op
>>
>> Patch:
>>
>> Benchmark (size) Mode Cnt
>> Score Error Units
>> StringConstructor.newStringFromArray 7 avgt 15
>> 14.666 ± 0.336 ns/op
>> StringConstructor.newStringFromArrayWithCharset 7 avgt 15
>> 14.582 ± 0.288 ns/op
>> StringConstructor.newStringFromArrayWithCharsetName 7 avgt 15
>> 20.339 ± 0.328 ns/op
>
> Claes Redestad has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Minimize, force inline, generalize
I'm also curious if returning the new length from `checkLength` would be
worthwhile
src/java.base/share/classes/java/util/Arrays.java line 3823:
> 3821: if (to - from < 0) {
> 3822: throw new IllegalArgumentException(from + " > " + to);
> 3823: }
Would it be beneficial to return the difference of `to` and `from` for caller
use?
Suggestion:
private static int checkLength(int from, int to) {
int newLength = to - from;
if (newLength < 0) {
throw new IllegalArgumentException(from + " > " + to);
}
return newLength;
src/java.base/share/classes/java/util/Arrays.java line 3870:
> 3868: private static byte[] copyOfRangeGeneric(byte[] original, int from,
> int to) {
> 3869: checkLength(from, to);
> 3870: int newLength = to - from;
```suggestion
int newLength = checkLength(from, to);
src/java.base/share/classes/java/util/Arrays.java line 3914:
> 3912: private static short[] copyOfRangeGeneric(short[] original, int
> from, int to) {
> 3913: checkLength(from, to);
> 3914: int newLength = to - from;
Suggestion:
int newLength = checkLength(from, to);
src/java.base/share/classes/java/util/Arrays.java line 3958:
> 3956: private static int[] copyOfRangeGeneric(int[] original, int from,
> int to) {
> 3957: checkLength(from, to);
> 3958: int newLength = to - from;
Suggestion:
int newLength = checkLength(from, to);
src/java.base/share/classes/java/util/Arrays.java line 4002:
> 4000: private static long[] copyOfRangeGeneric(long[] original, int from,
> int to) {
> 4001: checkLength(from, to);
> 4002: int newLength = to - from;
Suggestion:
int newLength = checkLength(from, to);
src/java.base/share/classes/java/util/Arrays.java line 4046:
> 4044: private static char[] copyOfRangeGeneric(char[] original, int from,
> int to) {
> 4045: checkLength(from, to);
> 4046: int newLength = to - from;
Suggestion:
int newLength = checkLength(from, to);
src/java.base/share/classes/java/util/Arrays.java line 4091:
> 4089: private static float[] copyOfRangeGeneric(float[] original, int
> from, int to) {
> 4090: checkLength(from, to);
> 4091: int newLength = to - from;
Suggestion:
int newLength = checkLength(from, to);
src/java.base/share/classes/java/util/Arrays.java line 4142:
> 4140: private static double[] copyOfRangeGeneric(double[] original, int
> from, int to) {
> 4141: checkLength(from, to);
> 4142: int newLength = to - from;
Suggestion:
int newLength = checkLength(from, to);
src/java.base/share/classes/java/util/Arrays.java line 4193:
> 4191: private static boolean[] copyOfRangeGeneric(boolean[] original, int
> from, int to) {
> 4192: checkLength(from, to);
> 4193: int newLength = to - from;
Suggestion:
int newLength = checkLength(from, to);
-------------
PR: https://git.openjdk.org/jdk/pull/12453
