8253639: Change os::attempt_reserve_memory_at parameter order

[stefank]

I propose that we change the parameter order from:
os::attempt_reserve_memory_at(size, addr, )

to:
os::attempt_reserve_memory_at(addr, size, )

This patch builds upon the changes in pull/357. There's currently no way to create an incremental review, but I want to get this out for review now. So, unfortunately you have to ignore the first commit and look at the second commit.

/label hotspot

---

Progress

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

Issue

• JDK-8253639: Change os::attempt_reserve_memory_at parameter order

Reviewers

• Thomas Schatzl (@tschatzl - Reviewer) ⚠️ Review applies to 3ba1826
• Ioi Lam (@iklam - Reviewer) ⚠️ Review applies to 3ba1826

Download

$ git fetch https://git.openjdk.java.net/jdk pull/359/head:pull/359
$ git checkout pull/359

[bridgekeeper]

👋 Welcome back stefank! 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]

@stefank
The hotspot label was successfully added.

[mlbridge]

Webrevs

• 01: Full (6bc920b)
• 00: Full (3ba1826)

[tstuefe]

Looks good to me.

I still learn to skara and just noticed that as a reviewer I cannot use /reviewer. Since this PR contains commits from some other PR, I don't know how to mark this as reviewed.

[stefank]

Thanks Thomas. You need to click "Files changed" then "Review Changes" to review this. I don't think there's a /reviewer command you can use. I'll ask.

[stefank]

Currently, the /reviewer command is only there to the PR owner to credit additional reviewers. I've created a Skara ticket asking if this could be enhanced:
https://bugs.openjdk.java.net/browse/SKARA-736

[tschatzl]

Parameter reordering looks good.

[openjdk]

@stefank 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 more details.

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

8253639: Change os::attempt_reserve_memory_at parameter order

Reviewed-by: tschatzl, iklam

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:

• fed3636: 8252219: C2: Randomize IGVN worklist for stress testing

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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.

[iklam]

Could you add an explanation in the bug report for the reason of this change?

[stefank]

Could you add an explanation in the bug report for the reason of this change?

Sure. I thought it was obvious, but I agree a comment would be good. I added:

The motivation is that it's simply awkward to have attempt_reserve_memory_at use the opposite order of most other memory range APIs.

Examples of APIs using the order addr, size:
1) void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset);
2) PVOID VirtualAlloc2(..., BaseAddress, Size, ...)
3) ReservedMemoryRegion(address base, size_t size)
4) MemRegion(HeapWord* start, size_t word_size)
5) ReservedSpace(char* base, size_t size
6) commit_memory(char* addr, size_t bytes, bool executable) 

[iklam]

Looks good to me.

[stefank]

Thanks all for reviewing!

[stefank]

Continuing this experiment to build a PR on top of another PR. I added a commit to parent PR pull/357, merged in master, and pushed pull/359's branch. "Files changed" now looks as expected, and only contains the changes relevant for this PR.

[stefank]

/integrate

[openjdk]

@stefank Since your change was applied there has been 1 commit pushed to the master branch:

• fed3636: 8252219: C2: Randomize IGVN worklist for stress testing

Your commit was automatically rebased without conflicts.

Pushed as commit ca1ed16.

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