RFR: 8289908: Skip bounds check for cases when String is constructed from entirely used byte[] [v4]

Сергей Цыпанов duke at openjdk.org
Wed Jul 13 15:11:25 UTC 2022


> We can skip bounds check and null check for Charset in case we use the array entirely and the Charset is either default one or proven to be non-null.
> 
> Benchmark results:
> 
> before
> 
> Benchmark                                                  Mode  Cnt  Score   Error  Units
> StringConstructor.newStringFromArray                       avgt   50  4,815 ± 0,154  ns/op
> StringConstructor.newStringFromArrayWithCharset            avgt   50  4,462 ± 0,068  ns/op
> StringConstructor.newStringFromArrayWithCharsetName        avgt   50  8,653 ± 0,040  ns/op
> StringConstructor.newStringFromRangedArray                 avgt   50  5,090 ± 0,066  ns/op
> StringConstructor.newStringFromRangedArrayWithCharset      avgt   50  4,550 ± 0,041  ns/op
> StringConstructor.newStringFromRangedArrayWithCharsetName  avgt   50  8,080 ± 0,055  ns/op
> 
> after
> 
> Benchmark                                                  Mode  Cnt  Score   Error  Units
> StringConstructor.newStringFromArray                       avgt   50  4,595 ± 0,053  ns/op
> StringConstructor.newStringFromArrayWithCharset            avgt   50  4,038 ± 0,062  ns/op
> StringConstructor.newStringFromArrayWithCharsetName        avgt   50  8,035 ± 0,031  ns/op
> StringConstructor.newStringFromRangedArray                 avgt   50  4,084 ± 0,007  ns/op
> StringConstructor.newStringFromRangedArrayWithCharset      avgt   50  4,014 ± 0,008  ns/op
> StringConstructor.newStringFromRangedArrayWithCharsetName  avgt   50  7,466 ± 0,071  ns/op

Сергей Цыпанов has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:

 - 8289908: Rework constructor
 - Merge branch 'master' into 8289908
 - 8289908: Fixed tests
 - Merge branch 'master' into 8289908
 - 8289908: Make constructor private and use trailing Void instead of int
 - 8289908: Skip bounds check for cases when String is constructed from entirely used byte[]

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/9407/files
  - new: https://git.openjdk.org/jdk/pull/9407/files/b7375cd3..f653a67b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9407&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9407&range=02-03

  Stats: 62100 lines in 564 files changed: 33281 ins; 20833 del; 7986 mod
  Patch: https://git.openjdk.org/jdk/pull/9407.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9407/head:pull/9407

PR: https://git.openjdk.org/jdk/pull/9407


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