8271732: Regression in StringBuilder.charAt bounds checking

[cl4es]

In #4738 we removed the checkIndex(value, count) call in ASB.charAt to avoid potentially getting two bounds checks in the UTF-16 case. Problem is this optimization cause a regression since StringUTF16.charAt(..) checks index against the length of the value array and not count.

A correct fix that still maintain the possible performance advantage reported by #4738 is to reinstate the checkIndex(value, count) and call StringUTF16.getChar instead of charAt.

---

Progress

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Issue

• JDK-8271732: Regression in StringBuilder.charAt bounds checking

Reviewers

• Alan Bateman (@AlanBateman - Reviewer)
• Naoto Sato (@naotoj - Reviewer)

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[AlanBateman]

This looks okay but surprised there wasn't a jtreg test that would have caught this before integration, maybe we should add a test as part of this change.

[openjdk]

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

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

8271732: Regression in StringBuilder.charAt bounds checking

Reviewed-by: alanb, 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 9 new commits pushed to the master branch:

• ec2fc38: 8272120: Avoid looking for standard encodings in "java." modules
• bd27bb9: 8272345: macos doesn't check os::set_boot_path() result
• 44f137f: 8271170: Add unit test for what jpackage app launcher puts in the environment
• cd2dbe5: 8272328: java.library.path is not set properly by Windows jpackage app launcher
• 9faab40: 8272330: C2: Cleanup profile counter scaling
• 75a0642: 8272335: runtime/cds/appcds/MoveJDKTest.java doesn't check exit codes
• 9ba8a12: 8269774: doclint reports missing javadoc comments for JavaFX properties if the docs are on the property method
• ec8d3ba: 8271159: [REDO] JDK-8249634 doclint should report implicit constructor as missing javadoc comments
• 6194227: 8272228: G1: G1CardSetInlinePtr Fix tautological assertion

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[naotoj]

LGTM.

[naotoj]

Would you want to also test non-Latin1, just in case?

[cl4es]

/integrate

[openjdk]

Going to push as commit a15b659.
Since your change was applied there have been 9 commits pushed to the master branch:

• ec2fc38: 8272120: Avoid looking for standard encodings in "java." modules
• bd27bb9: 8272345: macos doesn't check os::set_boot_path() result
• 44f137f: 8271170: Add unit test for what jpackage app launcher puts in the environment
• cd2dbe5: 8272328: java.library.path is not set properly by Windows jpackage app launcher
• 9faab40: 8272330: C2: Cleanup profile counter scaling
• 75a0642: 8272335: runtime/cds/appcds/MoveJDKTest.java doesn't check exit codes
• 9ba8a12: 8269774: doclint reports missing javadoc comments for JavaFX properties if the docs are on the property method
• ec8d3ba: 8271159: [REDO] JDK-8249634 doclint should report implicit constructor as missing javadoc comments
• 6194227: 8272228: G1: G1CardSetInlinePtr Fix tautological assertion

Your commit was automatically rebased without conflicts.

[openjdk]

@cl4es Pushed as commit a15b659.

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