8359920: Use names for frame types in stackmaps

[coleenp]

This uses names for frame types for stackmaps in the verifier and redefinition.
Tested with tier1-7.

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8359920: Use names for frame types in stackmaps (Enhancement - P4)

Reviewers

• Johan Sjölen (@jdksjolen - Reviewer) Review applies to 37b5c7ee
• Matias Saavedra Silva (@matias9927 - Reviewer) Review applies to 7d2e60c2
• Serguei Spitsyn (@sspitsyn - Reviewer) Review applies to 37b5c7ee
• David Holmes (@dholmes-ora - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/25870/head:pull/25870
$ git checkout pull/25870

Update a local copy of the PR:
$ git checkout pull/25870
$ git pull https://git.openjdk.org/jdk.git pull/25870/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 25870

View PR using the GUI difftool:
$ git pr show -t 25870

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/25870.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back coleenp! 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]

@coleenp 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:

8359920: Use names for frame types in stackmaps

Reviewed-by: dholmes, jsjolen, matsaave, sspitsyn

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 80 new commits pushed to the master branch:

• 116b854: 8351983: HttpCookie Parser Incorrectly Handles Cookies with Expires Attribute
• fdfc557: 8360131: Remove use of soon-to-be-removed APIs by CTW framework
• 54fec2b: 8360220: Deprecate and obsolete ParallelRefProcBalancingEnabled
• ... and 77 more: https://git.openjdk.org/jdk/compare/9a1c1f2efb1367ea8196b56d1b9b3b0841e4398d...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.

[openjdk]

@coleenp 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.

[mlbridge]

Webrevs

• 04: Full - Incremental (edec7b8e)
• 03: Full - Incremental (7d2e60c2)
• 02: Full - Incremental (107382e4)
• 01: Full - Incremental (c3d8d0fc)
• 00: Full (37b5c7ee)

[matias9927]

LGTM, thanks!

[dholmes-ora]

I find these definitions a little confusing. SAME_FRAME is actually 0-63, with SAME_LOCALS_1_STACK_ITEM_FRAME being 64-127. Given many of these frame types imply tag ranges it may be clearer to define enum's for the start and end of ranges as applicable eg.

enum {
  SAME_FRAME_START = 0,
  SAME_FRAME_END = 63,
  SAME_LOCALS_1_STACK_ITEM_FRAME_START = 64,
  SAME_LOCALS_1_STACK_ITEM_FRAME_END = 127,
  RESERVED_START = 128,
  RESERVED_END = 246,
  SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247,
  CHOP_FRAME_START = 248,
  CHOP_FRAME_END = 250,
  SAME_FRAME_EXTENDED = 251,
  APPEND_FRAME_START = 252,
  APPEND_FRAME_END = 254,
  FULL_FRAME = 255
}

and then adjust the code usage as appropriate e.g.

if (frame_type <= SAME_FRAME_END) {
...
if (frame_type <= SAME_LOCALS_1_STACK_ITEM_FRAME_END) {
  if (_first) {
    offset = frame_type - SAME_LOCALS_1_STACK_ITEM_FRAME_START;
...

What do you think?

[coleenp]

I wasn't really up for a big rewrite but having the complete set of names would be really good.

[sspitsyn]

This looks good.
I was also thinking about frame_type ranges but no ideas on any improvements.

[coleenp]

tiers 1-4 passed with changes suggested by @dholmes-ora

[matias9927]

Updated change looks good!

[dholmes-ora]

Thanks for applying this @coleenp !

I have a couple of suggested changes that to me make it more obvious what case(s) we are dealing with, but up to you whether to apply them or not. The more I look at this code the more it cries out to be restructured, to me.

Thanks

[coleenp]

Yes, I like all of these changes. One would have prevented me from a transient bug I had. @matias9927 and I chatted about restructuring this code in the future which seems like a good idea. All in all, these tags and your suggestions are really helpful.

Also verified and am testing your suggested changes.

[dholmes-ora]

Thanks Coleen!