8263392: Allow current thread to be specified in ExceptionMark

[iklam]

ExceptionMark, usually used via the EXCEPTION_MARK marco, is used to guarantee that an exception is not thrown within a block of code. I made two changes to improve efficiency:

• Avoid calling Thread::current() if a thread object is already available.
• Avoid passing a reference to the ExceptionMark constructor. This helps C++ generate slightly better code.

This new variant of ExceptionMark is mainly intended for future clean up of TRAPS/CHECK/THREAD code, where an exception context is temporarily needed but we will guarantee that all exceptions will be handled. I modified SharedRuntime::monitor_exit_helper() to use this pattern:

Old style:

void a_func_that_never_throws() {
  EXCEPTION_MARK;
  a_func_that_could_throw(THREAD);
  if (HAS_PENDING_EXCEPTION) {
      // handle it
    CLEAR_PENDING_EXCEPTION;
  }
}

New style:

void a_func_that_never_throws(Thread* current) { // pass thread to avoid calling Thread::current()
  ExceptionMark em(current);
  Thread* THREAD = current; // For exception macros.
  a_func_that_could_throw(THREAD);
  if (HAS_PENDING_EXCEPTION) {
      // handle it
      CLEAR_PENDING_EXCEPTION;
  }
}

---

Progress

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

Issue

• JDK-8263392: Allow current thread to be specified in ExceptionMark

Reviewers

• David Holmes (@dholmes-ora - Reviewer) ⚠️ Review applies to 91eefd7
• Calvin Cheung (@calvinccheung - Reviewer)
• Coleen Phillimore (@coleenp - Reviewer)
• Yumin Qi (@yminqi - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/2950/head:pull/2950
$ git checkout pull/2950

[bridgekeeper]

👋 Welcome back iklam! 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]

@iklam The following labels will be automatically applied to this pull request:

• hotspot
• serviceability

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

[iklam]

/label remove serviceability

[openjdk]

@iklam
The serviceability label was successfully removed.

[mlbridge]

Webrevs

• 01: Full - Incremental (53a016d)
• 00: Full (91eefd7)

[dholmes-ora]

Looks good! Thanks for doing this cleanup.

David

[openjdk]

@iklam 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:

8263392: Allow current thread to be specified in ExceptionMark

Reviewed-by: dholmes, ccheung, coleenp, minqi

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 1 new commit pushed to the master branch:

• 0c718ab: 8262277: URLClassLoader.getResource throws undocumented IllegalArgumentException

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[calvinccheung]

Looks good.

[coleenp]

This looks good. It would be nice to replace more EXCEPTION_MARK as we find them.

[yminqi]

This change is good.

[iklam]

Thanks @dholmes-ora @calvinccheung @coleenp @yminqi for the review.
/integrate

[openjdk]

@iklam Since your change was applied there have been 2 commits pushed to the master branch:

• 4d1c08c: 8263616: 'Deprecatd' typo in src/hotspot/share/classfile/classFileParser.cpp
• 0c718ab: 8262277: URLClassLoader.getResource throws undocumented IllegalArgumentException

Your commit was automatically rebased without conflicts.

Pushed as commit 1e57087.

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