8250801: Add clhsdb "threadcontext" command

[plummercj]

SA has the ability to fetch the thread's registers via the thread context. It would be nice to allow access to the registers from clhsdb. This plays in well with the enhancements being done to PointerFinder as part of JDK-8247514. Many of the register values will then be automatically displayed as symbols, Methods, Threads, stack offsets, nmethods, interpreter codelets, etc.

During some recent debugging I did I found it useful to dump a thread's registers in this manner. Although in this case I was inlining the code in the part of SA where I wanted to see the registers, having it as a clhsdb command would not only be useful to user, but also useful when debugging SA because it would serve as a code snippet to copy-n-paste where needed.

The syntax is:

threadcontext [-v] { -a | id }

Where -a displays all threads, and "id" is used to display a specific thread. This is the same argument syntax as some other commands that let you choose all threads or just one thread, such as the "thread" and "where" commands. -v just means more verbose output, whereas without it for the most part each register printed will just take up one line.

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Progress

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Issue

• JDK-8250801: Add clhsdb "threadcontext" command

Reviewers

• Serguei Spitsyn (@sspitsyn - Reviewer)
• Kevin Walls (@kevinjwalls - Committer)

Reviewing

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[mlbridge]

Webrevs

• 01: Full - Incremental (417dd9cb)
• 00: Full (936b5579)

[sspitsyn]

Chris,
I only have one question (inlined).
Other than that it looks good to me.
Thanks,
Serguei

[kevinjwalls]

Looks useful to expose this info if we have it!

[openjdk]

@plummercj 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:

8250801: Add clhsdb "threadcontext" command

Reviewed-by: sspitsyn, kevinw

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At the time when this comment was updated there had been 43 new commits pushed to the master branch:

• 191f730: Merge
• 95a3010: 8275830: C2: Receiver downcast is missing when inlining through method handle linkers
• 58b5fb3: 8265317: [vector] assert(payload->is_object()) failed: expected 'object' value for scalar-replaced boxed vector but got: NULL
• 06f3713: 8279379: GHA: Print tests that are in error
• e7244c1: 8278966: two microbenchmarks tests fail "assert(!jvms->method()->has_exception_handlers()) failed: no exception handler expected" after JDK-8275638
• b4b0328: 8278824: Uneven work distribution when scanning heap roots in G1
• 99a8351: 8279386: Remove duplicate RefProcPhaseTimeTracker
• d1e6f26: 8279351: [TESTBUG] SADebugDTest.java does not handle "Address already in use" error
• 93c7d90: 8278282: G1: Log basic statistics for evacuation failure
• 1ffdc52: 8279412: [JVMCI] failed speculations list must outlive any nmethod that refers to it
• ... and 33 more: https://git.openjdk.java.net/jdk/compare/eaefb1a1ed9edea440628e3a5c5483ebd52bfcb0...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.

[plummercj]

/integrate

[openjdk]

Going to push as commit bdfa15d.
Since your change was applied there have been 204 commits pushed to the master branch:

• fd9fb9a: 8279194: Add Annotated Memory Viewer feature to SA's HSDB
• 848b16a: 8272746: ZipFile can't open big file (NegativeArraySizeException)
• b734dc8: 8280055: JFR: Improve ObjectContext implementation
• 7acc4c7: 8280058: JFR: StreamUtils::getJfrRepository(Process) should print stdout and stderr
• 88a8b23: 8280076: Unify IGV and IR printing
• 9e3f68d: 8279290: symbol not found error, implicit lambdas and diamond constructor invocations
• 9eb50a5: 8280010: Remove double buffering of InputStream for Properties.load
• 64c0c0e: 8276563: Undefined Behaviour in class Assembler
• d175d33: 8280079: Serial: Remove empty Generation::prepare_for_verify
• 1725f77: 8280029: G1: "Overflow during reference processing, can not continue" on x86_32
• ... and 194 more: https://git.openjdk.java.net/jdk/compare/eaefb1a1ed9edea440628e3a5c5483ebd52bfcb0...master

Your commit was automatically rebased without conflicts.

[openjdk]

@plummercj Pushed as commit bdfa15d.

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