8270307: C2: assert(false) failed: bad AD file after JDK-8267687

[y1yang0]

One input of ConvI2L becomes Top, which causes all nodes in the chain becoming Top, but this CMoveLNode does not change, only its input becomes Top.

  Pop  2146  CMoveL  === _  351  1  2149  [[ 2182  2187 ]]   Type:long !orig=810,696,[439],288 !jvms: Test::vMeth @ bci:78 (line 8)
BreakAtNode: _idx=2461 _debug_idx=102702461 orig._idx=2146 orig._debug_idx=92502146
<               < 2146  CMoveL  === _ _  1 _  [[]]   Type:long !orig=810,696,[439],288 !jvms: Test::vMeth @ bci:78 (line 8)
> long           2461  CMoveL  === _  2458  2149  1  [[ 2187  2182 ]]   Type:long !orig=2146,810,696,[439],288 !jvms: Test::vMeth @ bci:78 (line 8)

This CMoveLNode(CMove Binary(.. ..) (Binary .. Con#Top)) can not match any rules in the instruction selection phase and finally hits the assert. The proposed fix disables further optimizations if inputs of CMoveNode are type of Top.

Testing:

• test/hotspot/jtreg/compiler/c2
• github presubmit tests
• attached fuzzer test
• TestCMoveHasTopInput

---

Progress

• Change must not contain extraneous whitespace
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Issue

• JDK-8270307: C2: assert(false) failed: bad AD file after JDK-8267687

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer)
• Tobias Hartmann (@TobiHartmann - Reviewer)

Contributors

• Kuai Wei <kuaiwei.kw@alibaba-inc.com>

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Webrevs

• 00: Full (fa520058)

[vnkozlov]

Looks good.

[openjdk]

@kelthuzadx 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:

8270307: C2: assert(false) failed: bad AD file after JDK-8267687

Co-authored-by: Kuai Wei <kuaiwei.kw@alibaba-inc.com>
Reviewed-by: kvn, thartmann

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At the time when this comment was updated there had been 1 new commit pushed to the master branch:

• c130451: 8269752: C2: assert(false) failed: Bad graph detected in build_loop_late

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[TobiHartmann]

Looks good to me.

[y1yang0]

Thanks Vladimir and Tobias for reviews!

[y1yang0]

/contributor add Kuai Wei kuaiwei.kw@alibaba-inc.com

[openjdk]

@kelthuzadx
Contributor Kuai Wei <kuaiwei.kw@alibaba-inc.com> successfully added.

[y1yang0]

/integrate

[openjdk]

Going to push as commit 0cec11d.
Since your change was applied there has been 1 commit pushed to the master branch:

• c130451: 8269752: C2: assert(false) failed: Bad graph detected in build_loop_late

Your commit was automatically rebased without conflicts.

[openjdk]

@kelthuzadx Pushed as commit 0cec11d.

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