8379629: Add StressDeepIGVNRevisit diagnostic flag to force deep revisit in all IGVN optimize() calls

[krk]

Add StressDeepIGVNRevisit diagnostic flag (all/random) to force deep revisit in PhaseIterGVN::optimize() calls, helping uncover latent optimizer bugs.

---

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-8379629: Add StressDeepIGVNRevisit diagnostic flag to force deep revisit in all IGVN optimize() calls (Enhancement - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/30535/head:pull/30535
$ git checkout pull/30535

Update a local copy of the PR:
$ git checkout pull/30535
$ git pull https://git.openjdk.org/jdk.git pull/30535/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 30535

View PR using the GUI difftool:
$ git pr show -t 30535

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/30535.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back krk! 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 change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

@krk The following label will be automatically applied to this pull request:

• hotspot

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

[mlbridge]

Webrevs

• 02: Full - Incremental (a4628b9f)
• 01: Full - Incremental (66d5b18c)
• 00: Full (53941b7f)

[robcasloz]

/cc hotspot-compiler

[openjdk]

@robcasloz
The hotspot-compiler label was successfully added.

[anton-seoane]

I see all the product DIAGNOSTIC stress flags at the beginning of the file. I'm unsure if that's by design to facilitate discovery or if in your case it's fine to keep it below the UseDeepIGVNRevisit. Maybe someone else can shed a light on this.