8325730: StringBuilder.toString allocation for the empty String

[shipilev]

Clean backport to fix the regression introduced in JDK 19.

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8325730 needs maintainer approval

Issue

• JDK-8325730: StringBuilder.toString allocation for the empty String (Bug - P4 - Approved)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk22u.git pull/70/head:pull/70
$ git checkout pull/70

Update a local copy of the PR:
$ git checkout pull/70
$ git pull https://git.openjdk.org/jdk22u.git pull/70/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 70

View PR using the GUI difftool:
$ git pr show -t 70

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk22u/pull/70.diff

Webrev

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[bridgekeeper]

👋 Welcome back shade! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

⚠️ @shipilev This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

Webrevs

• 00: Full (580834ef)

[shipilev]

/approval request Clean backport to fix the regression introduced in JDK 19. Applies cleanly. Tests pass. The benchmark improvements are the same as in mainline.

[openjdk]

@shipilev
8325730: The approval request has been created successfully.

[openjdk]

@shipilev 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:

8325730: StringBuilder.toString allocation for the empty String

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 23 new commits pushed to the master branch:

• cffdef1: 8326936: RISC-V: Shenandoah GC crashes due to incorrect atomic memory operations
• 6ac9326: 8327391: Add SipHash attribution file
• cebe57d: 8321075: RISC-V: UseSystemMemoryBarrier lacking proper OS support
• 648a161: 8323519: Add applications/ctw/modules to Hotspot tiered testing
• d6fc2b1: 8325862: set -XX:+ErrorFileToStderr when executing java in containers for some container related jtreg tests
• 324d7cc: 8327467: Bump version numbers for 22.0.2
• 882978f: 8325313: Header format error in TestIntrinsicBailOut after JDK-8317299
• dd4dc38: 8317299: safepoint scalarization doesn't keep track of the depth of the JVM state
• b73c15e: 8323154: C2: assert(cmp != nullptr && cmp->Opcode() == Op_Cmp(bt)) failed: no exit test
• 78df8c1: 8325672: C2: allocate PhaseIdealLoop::_loop_or_ctrl from C->comp_arena()
• ... and 13 more: https://git.openjdk.org/jdk22u/compare/b6ed6d8f337ae79b6bc4274fba0b4f4722a627f2...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.

[shipilev]

/integrate

[openjdk]

Going to push as commit b2275aa.
Since your change was applied there have been 27 commits pushed to the master branch:

• fd11382: 8324834: Use _LARGE_FILES on AIX
• f510fe8: 8326891: Prefer RPATH over RUNPATH for $ORIGIN rpaths in internal JDK binaries
• 6b307d7: 8327059: os::Linux::print_proc_sys_info add swappiness information
• f5cfcbb: 8326140: src/jdk.accessibility/windows/native/libjavaaccessbridge/AccessBridgeJavaEntryPoints.cpp ReleaseStringChars might be missing in early returns
• cffdef1: 8326936: RISC-V: Shenandoah GC crashes due to incorrect atomic memory operations
• 6ac9326: 8327391: Add SipHash attribution file
• cebe57d: 8321075: RISC-V: UseSystemMemoryBarrier lacking proper OS support
• 648a161: 8323519: Add applications/ctw/modules to Hotspot tiered testing
• d6fc2b1: 8325862: set -XX:+ErrorFileToStderr when executing java in containers for some container related jtreg tests
• 324d7cc: 8327467: Bump version numbers for 22.0.2
• ... and 17 more: https://git.openjdk.org/jdk22u/compare/b6ed6d8f337ae79b6bc4274fba0b4f4722a627f2...master

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev Pushed as commit b2275aa.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.