8266438: Compile::remove_useless_nodes does not remove opaque nodes

[TobiHartmann]

JDK-8255026 refactored the code in Compile::remove_useless_nodes and as a result, useless nodes are no longer removed from the _predicate_opaqs list. Before the change, the call to remove_macro_node took care of this:

jdk/src/hotspot/share/opto/compile.hpp

Lines 676 to 684 in 194bcec

	void remove_macro_node(Node* n) {
	// this function may be called twice for a node so we can only remove it
	// if it's still existing.
	_macro_nodes.remove_if_existing(n);
	// remove from _predicate_opaqs list also if it is there
	if (predicate_count() > 0) {
	_predicate_opaqs.remove_if_existing(n);
	}
	}

But the new code only removes nodes from the _macro_nodes list. Useless nodes should be removed from the _skeleton_predicate_opaqs list as well.

I've seen failures due to this with a change in Valhalla (where we call remove_useless_nodes more often) but not in mainline. I think this should still be fixed in mainline.

Thanks,
Tobias

---

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Issue

• JDK-8266438: Compile::remove_useless_nodes does not remove opaque nodes

Reviewers

• Vladimir Ivanov (@iwanowww - Reviewer)
• Christian Hagedorn (@chhagedorn - Reviewer)

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Webrevs

• 00: Full (906b703a)

[iwanowww]

Looks good.

[openjdk]

@TobiHartmann 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:

8266438: Compile::remove_useless_nodes does not remove opaque nodes

Reviewed-by: vlivanov, chagedorn

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At the time when this comment was updated there had been 8 new commits pushed to the master branch:

• 880c138: 8265349: vmTestbase/../stress/compiler/deoptimize/Test.java fails with OOME due to CodeCache exhaustion.
• 001c514: 8265322: C2: Simplify control inputs for BarrierSetC2::obj_allocate
• 194bcec: 8265984: Concurrent GC: Some tests fail "assert(is_frame_safe(f)) failed: Frame must be safe"
• 1d9ea3a: 8266083: Shenandoah: Consolidate dedup/no dedup oop closures
• 80941f4: 8234446: Post-CMS workgroup hierarchy cleanup
• ac760c7: 8266295: Remove unused _concurrent_iteration_safe_limit
• b42d496: 8266388: C2: Improve constant ShiftCntV on x86
• 05cfac9: 8266412: Remove redundant TemplateInterpreter entries

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.

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[TobiHartmann]

Thanks for the review, Vladimir!

[chhagedorn]

Looks good!

[TobiHartmann]

Thanks for the review, Christian!

[TobiHartmann]

/integrate

[openjdk]

@TobiHartmann Since your change was applied there have been 18 commits pushed to the master branch:

• 141cc2f: 8261527: Record page size used for underlying mapping in ReservedSpace
• 8e071c4: 8265784: [C2] Hoisting of DecodeN leaves MachTemp inputs behind
• ce1bc9d: 8266432: ZGC: GC allocation stalls can trigger deadlocks
• 30ccd80: 8264950: Set opaque for JTooltip in config file of NimbusLookAndFeel
• cfdf4a7: 8266449: cleanup jtreg tags in compiler/intrinsics/sha/cli tests
• 3544a9d: 8266391: Replace use of reflection in jdk.internal.platform.Metrics
• 020236c: 8264786: [macos] All Swing/AWT apps cause Allow Notifications prompt to appear when app is launched
• 45760d4: 8266320: (bf) ReadOnlyBufferException in heap buffer put(String,int,int) should not be conditional
• ff65920: 8265491: Math Signum optimization for x86
• 55cc0af: 8266185: Shenandoah: Fix incorrect comment/assertion messages
• ... and 8 more: https://git.openjdk.java.net/jdk/compare/c5dc657f0be90bd594663dcc612f40a930c2bbe7...master

Your commit was automatically rebased without conflicts.

Pushed as commit b651904.

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