8343067: C2: revisit constant-offset AddP chains after successful input idealizations

[robcasloz]

This changeset re-adds a constant-offset AddP node (u) to C2's IGVN worklist when its address is given by another AddP node (use) whose offset has changed. This makes it possible for AddPNode::Ideal to flatten the address computation in cases where the offset of the latter (use->in(AddPNode::Offset)) is found to be constant during IGVN:

The end result is the generation of fewer explicit address computation instructions.

Testing

Functionality

• tier1-5 (linux-x64, windows-x64, macosx-x64, linux-aarch64, macosx-aarch64; release and debug mode).

Performance

• Tested performance on a set of standard benchmark suites (DaCapo, SPECjbb2015, SPECjvm2008). No significant change was observed.

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
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Issue

• JDK-8343067: C2: revisit constant-offset AddP chains after successful input idealizations (Enhancement - P4)

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer)
• Vladimir Ivanov (@iwanowww - Reviewer)

Reviewing

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[openjdk]

@robcasloz This change now passes all automated pre-integration checks.

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

8343067: C2: revisit constant-offset AddP chains after successful input idealizations

Reviewed-by: kvn, vlivanov

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At the time when this comment was updated there had been 86 new commits pushed to the master branch:

• d4d9831: 8340454: C2 EA asserts with "previous reducible Phi is no longer reducible before SUT"
• 2a1ae0f: 8331008: Implement JEP 478: Key Derivation Function API (Preview)
• 847cc5e: 8343173: Remove ZGC-specific non-JVMCI test groups
• 3fab8e3: 8341903: Implementation of Scoped Values (Fourth Preview)
• 839de82: 8332744: [REDO] 'internal proprietary API' diagnostics if --system is configured to an earlier JDK version
• 8cb1221: 8343532: Test test/hotspot/jtreg/runtime/cds/appcds/jigsaw/addmods/AddmodsOption.java fails on Linux ppc64le after JDK-8319343
• fbf9b96: 8343480: Remove unnecessary @SuppressWarnings annotations (javadoc)
• f95097c: 8343482: Remove unnecessary @SuppressWarnings annotations (net)
• c799cad: 8343486: Remove unnecessary @SuppressWarnings annotations and -Xlint:-foo options
• 0b733e9: 8336874: WhiteBoxAPI: assert(!method->is_abstract() && (osr_bci == InvocationEntryBci || !method->is_native())) failed: cannot compile abstract/native methods
• ... and 76 more: https://git.openjdk.org/jdk/compare/388d44fbf0126f253860edc88c2efd57f86e5a2b...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]

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[mlbridge]

Webrevs

• 01: Full - Incremental (deb7c4e1)
• 00: Full (6dcbb0c6)

[vnkozlov]

n == use->in(AddPNode::Offset) result can be saved outside loop in local var.

[robcasloz]

Thanks, done (commit deb7c4e).

[vnkozlov]

Good.

[iwanowww]

Looks good.

[robcasloz]

Thanks for reviewing @vnkozlov and @iwanowww!

[robcasloz]

/integrate

[openjdk]

Going to push as commit ec13364.
Since your change was applied there have been 158 commits pushed to the master branch:

• 5ca6698: 8341176: Permit access to diagnostics for transient snippets
• a93bd9d: 8343810: [s390x] is_uimm* methods should take unsigned arguments
• f12c370: 8343118: [TESTBUG] java/awt/PrintJob/PrintCheckboxTest/PrintCheckboxManualTest.java fails with rror. Can't find HTML file PrintCheckboxManualTest.html
• ae6bb3c: 8343824: Remove unused InstructionFlags in C1
• 5b2f7f3: 8343837: Remove unnecessary reinterpret_cast from C2AccessValuePtr
• 5f338e9: 8342946: Replace predicate walking code in Loop Unrolling with a predicate visitor
• e1d684c: 8342650: Move getChars to DecimalDigits
• ca69a53: 8211033: Clean up the processing -classpath argument not to set LM_CLASS
• 7b0f273: 8343894: ProblemList javax/management/remote/mandatory/notif/EmptyDomainNotificationTest.java
• 74ae3c6: 8343650: Reuse StringLatin1::putCharsAt and StringUTF16::putCharsAt
• ... and 148 more: https://git.openjdk.org/jdk/compare/388d44fbf0126f253860edc88c2efd57f86e5a2b...master

Your commit was automatically rebased without conflicts.

[openjdk]

@robcasloz Pushed as commit ec13364.

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