8253588: C1: assert(false) failed: unknown register on x86_32 only with -XX:+TraceLinearScanLevel=4

[chhagedorn]

JDK-8251093 introduced some additional logging of intervals and its registers in various places. On 32-bit only, we could have two registers for an interval. A hi-register is only used when the interval has _num_phys_regs set to 2. In one such place (L5448), we log the hi-register hint_regHi. On L5441, however, we can assign it an invalid register number when _num_phys_regs is 1. That was not a problem before JDK-8251093 as we only used hint_regHi later after a _num_phys_regs == 2 check on L5484. But the additional logging is performed earlier resulting in this assertion failure when trying to log the invalid hint_regHi register.

Thanks,
Christian

---

Progress

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Issue

• JDK-8253588: C1: assert(false) failed: unknown register on x86_32 only with -XX:+TraceLinearScanLevel=4

Reviewers

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

Download

$ git fetch https://git.openjdk.java.net/jdk pull/356/head:pull/356
$ git checkout pull/356

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[mlbridge]

Webrevs

• 00: Full (29ed779)

[TobiHartmann]

Looks reasonable to me.

[openjdk]

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

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8253588: C1: assert(false) failed: unknown register on x86_32 only with -XX:+TraceLinearScanLevel=4

Reviewed-by: thartmann, kvn

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At the time when this comment was updated there had been 237 new commits pushed to the master branch:

• 7ec9c8e: 8233214: Remove runtime code not needed with CMS removed
• 536b35b: 8254319: Shenandoah: Interpreter native-LRB needs to activate during HAS_FORWARDED
• be26972: 8253379: [windows] Several jpackage tests failed with error code 1638
• 52e45a3: 8229186: Improve error messages for TestStringIntrinsics failures
• 6d2c1a6: 8254292: Update JMH devkit to 1.26
• 2bbf8a2: 8245543: Cgroups: Incorrect detection logic on some systems (still reproducible)
• aaa0a2a: 8254297: Zero and Minimal VMs are broken with undeclared identifier 'DerivedPointerTable' after JDK-8253180
• 7e80c98: 8254261: fix javadocs in jdk.test.lib.Utils
• d4b5dfd: 8253857: Shenandoah: Bugs in ShenandoahEvacOOMHandler related code
• e9c1905: 8253740: [PPC64] Minor interpreter cleanup
• ... and 227 more: https://git.openjdk.java.net/jdk/compare/3fe5886baf93dbbeba7baac4dad5876eeb7f9f5b...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.

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[vnkozlov]

Good.

[chhagedorn]

Thank you Tobias and Vladimir for your reviews!

[chhagedorn]

/integrate

[openjdk]

@chhagedorn Since your change was applied there have been 250 commits pushed to the master branch:

• 59378a1: 8254164: G1 only removes self forwarding pointers for last collection set increment
• bf46acf: 8254028: G1 incorrectly updates scan_top for collection set regions during preparation of evacuation
• a2bb4c6: 8254314: Shenandoah: null checks in c2 should not skip over native load barrier
• c73a0ff: 8252105: Parallel heap inspection for ZCollectedHeap
• 45b09a3: 8253833: mutexLocker assert_locked_or_safepoint should not access VMThread state from non-VM-thread
• 77c7762: 8254353: Remove unused non-product flags
• d3069ac: 8254362: x86_32 builds fail after JDK-8253180
• 25001c5: 8254352: 3 compiler tests failed with "assert(allocates2(pc)) failed: not in CodeBuffer memory"
• d43f141: 8254351: Minimal VM build fails with undeclared identifier 'MaxVectorSize' after JDK-8252847
• cc52358: 8254335: logging/logStream.hpp includes memory/resourceArea.hpp but doesn't need it
• ... and 240 more: https://git.openjdk.java.net/jdk/compare/3fe5886baf93dbbeba7baac4dad5876eeb7f9f5b...master

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Pushed as commit 13fe054.

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