8269775: compiler/codegen/ClearArrayTest.java failed with "assert(false) failed: bad AD file"

[sviswa7]

The following test failed in JDK17
compiler/codegen/ClearArrayTest.java
with assert(false) failed: bad AD file

The problem is that no match is found for platforms not supporting avx512vlbw for constant input.

Per analysis from Dean Long and Vladimir Kozlov:
This is due to rep_stos rules for small clear array which use !n->in(2)->bottom_type()->is_long()->is_con().
This prevents the rule from matching with a constant --> register conversion.
Removing !is_con() from rep_stos for small clear array fixes the issue.
We also add appropriate "ins_cost" to all ClearArray rules, so that in the case of multiple matches, we break the tie based on ins_cost.

Best Regards,
Sandhya

---

Progress

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Issue

• JDK-8269775: compiler/codegen/ClearArrayTest.java failed with "assert(false) failed: bad AD file"

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer)
• Dean Long (@dean-long - Reviewer)

Reviewing

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Update a local copy of the PR:
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$ git pr checkout 199

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[bridgekeeper]

👋 Welcome back sviswanathan! 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]

@sviswa7 The following label will be automatically applied to this pull request:

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[mlbridge]

Webrevs

• 01: Full - Incremental (e8671b0b)
• 00: Full (f3380586)

[vnkozlov]

You need to fix x86_32.ad file too.

[vnkozlov]

I don't think you need it here. There are no other ClearArray conflicting instructions for small copy and AVX <= 2.

[vnkozlov]

Add () around UseAVX > 2 as in other place.

[vnkozlov]

@sviswa7 Please, file separate RFE to improve this ClearArrayTest test which should include all cases we have in .ad file:

1. large vs small
2. constant vs variable length

[vnkozlov]

I verified that with this fix rep_stos_im() or rep_stos_evex() will be used depending on avx512vlbw support.
Good!

[sviswa7]

RFE for test filed: https://bugs.openjdk.java.net/browse/JDK-8269789

[sviswa7]

@vnkozlov I have implemented all your review comments. Please take a look.

[vnkozlov]

Looks good.
I am currently running tests. I will approve when they pass.

[vnkozlov]

Testing passed.

[openjdk]

@sviswa7 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:

8269775: compiler/codegen/ClearArrayTest.java failed with "assert(false) failed: bad AD file"

Reviewed-by: kvn, dlong

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:

• 5644c4f: 8265132: C2 compilation fails with assert "missing precedence edge"

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[sviswa7]

@vnkozlov Please let me know if I can go ahead and integrate.

[vnkozlov]

Wait Dean's review. It is fine if you push tomorrow.

[jatin-bhateja]

Thanks @sviswa7 , I missed putting this change in my last check-in, attaching instruction costs will resolve conflicts and select instruction with minimum cost in case of multiple matches in this BURS based instruction selection.

[sviswa7]

Thanks a lot @vnkozlov @dean-long for the review and all the help.

[sviswa7]

/integrate

[openjdk]

Going to push as commit 6f0e8e7.
Since your change was applied there have been 4 commits pushed to the master branch:

• c4ea13e: 8269543: The warning for System::setSecurityManager should only appear once for each caller
• 2db9005: 8262017: C2: assert(n != __null) failed: Bad immediate dominator info.
• 7bc96db: 8269771: assert(tmp == _callprojs.fallthrough_catchproj) failed: allocation control projection
• 5644c4f: 8265132: C2 compilation fails with assert "missing precedence edge"

Your commit was automatically rebased without conflicts.

[openjdk]

@sviswa7 Pushed as commit 6f0e8e7.

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