8285001: Simplify StringLatin1.regionMatches

[cl4es]

There is no pair of character values in the latin1 range (0-255) that will make the condition at line 401 in StringLatin1.java true, so this test can be removed.

Added a test and a microbenchmark (which as expected sees a few ns/op improvement from this change). Took the opportunity to tune the default settings for the micro to reduce runtime from 30+ minutes to 3 with no discernible degradation of quality.

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed

Issue

• JDK-8285001: Simplify StringLatin1.regionMatches

Reviewers

• Roger Riggs (@RogerRiggs - Reviewer) ⚠️ Review applies to a8894f7
• Naoto Sato (@naotoj - Reviewer) ⚠️ Review applies to a8894f7

Reviewing

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Checkout this PR locally:
$ git fetch https://git.openjdk.java.net/jdk pull/8292/head:pull/8292
$ git checkout pull/8292

Update a local copy of the PR:
$ git checkout pull/8292
$ git pull https://git.openjdk.java.net/jdk pull/8292/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 8292

View PR using the GUI difftool:
$ git pr show -t 8292

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Download this PR as a diff file:
https://git.openjdk.java.net/jdk/pull/8292.diff

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[openjdk]

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[mlbridge]

Webrevs

• 01: Full - Incremental (434a0fd2)
• 00: Full (a8894f79)

[RogerRiggs]

Nice Catch!

[openjdk]

@cl4es This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8285001: Simplify StringLatin1.regionMatches

Reviewed-by: rriggs, naoto

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 51 new commits pushed to the master branch:

• 5d1ec54: 8285007: Use correct lookup mode for MethodHandleStatics.UNSAFE
• fb469fb: 8284893: Fix typos in java.base
• 4594696: 8284903: Fix typos in hotspot
• 13fb1ee: 8284697: Avoid parsing the doc comment of an element that is not documented
• eb9c457: 8284856: Add a test case for checking UnicodeScript entity numbers
• a5bb210: 8285012: Problemlist gc/arguments/TestUseCompressedOopsFlagsWithUlimit.java
• da3d8b1: 8284539: Configure --with-source-date=version fails on MacOS
• ac77b63: 8284725: Fix include guard in jfrbitset.hpp
• 595c8b8: 8284999: Remove remaining files in src/samples
• 8d96ab0: 8280761: UseCompressedOops should be set after limit_heap_by_allocatable_memory
• ... and 41 more: https://git.openjdk.java.net/jdk/compare/339005dbc99e94ed094612c7b34eb0c93ca1f8c1...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[naotoj]

Nice Catch!

+1

[cl4es]

Thanks for reviews!
/integrate

[openjdk]

Going to push as commit e307bc8.
Since your change was applied there have been 51 commits pushed to the master branch:

• 5d1ec54: 8285007: Use correct lookup mode for MethodHandleStatics.UNSAFE
• fb469fb: 8284893: Fix typos in java.base
• 4594696: 8284903: Fix typos in hotspot
• 13fb1ee: 8284697: Avoid parsing the doc comment of an element that is not documented
• eb9c457: 8284856: Add a test case for checking UnicodeScript entity numbers
• a5bb210: 8285012: Problemlist gc/arguments/TestUseCompressedOopsFlagsWithUlimit.java
• da3d8b1: 8284539: Configure --with-source-date=version fails on MacOS
• ac77b63: 8284725: Fix include guard in jfrbitset.hpp
• 595c8b8: 8284999: Remove remaining files in src/samples
• 8d96ab0: 8280761: UseCompressedOops should be set after limit_heap_by_allocatable_memory
• ... and 41 more: https://git.openjdk.java.net/jdk/compare/339005dbc99e94ed094612c7b34eb0c93ca1f8c1...master

Your commit was automatically rebased without conflicts.

[openjdk]

@cl4es Pushed as commit e307bc8.

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