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8257166: [lworld] CCP fails to optimize FlatArrayCheckNode #282

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@TobiHartmann TobiHartmann commented Nov 27, 2020

We hit assert(!t->is_flat() && !t->is_not_flat()) failed: Should have been optimized out during macro expansion of a FlatArrayCheckNode because the input array is known to be not flat but the check hasn't been optimized out by IGVN. The problem is that when CCP processes the node via FlatArrayCheckNode::Value the type immediately goes from TOP to BOTTOM because the input array hasn't been processed yet (still has type TOP). Afterwards, the node is not processed anymore although the type could be improved once the input array has been processed and is now known to be not flat.

We should add verification code that catches such cases. I've filed JDK-8257197 to do this in mainline. A quick prototype suggests that we have multiple similar issues in mainline code.



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Build ✔️ (5/5 passed) ✔️ (2/2 passed) ✔️ (2/2 passed)
Test (tier1) (1/9 failed) (8/9 running) (8/9 running)

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  • JDK-8257166: [lworld] CCP fails to optimize FlatArrayCheckNode


$ git fetch pull/282/head:pull/282
$ git checkout pull/282

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@bridgekeeper bridgekeeper bot commented Nov 27, 2020

👋 Welcome back thartmann! A progress list of the required criteria for merging this PR into lworld will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

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@openjdk openjdk bot commented Nov 27, 2020

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

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8257166: [lworld] CCP fails to optimize FlatArrayCheckNode

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@TobiHartmann TobiHartmann commented Nov 27, 2020


@openjdk openjdk bot closed this Nov 27, 2020
@openjdk openjdk bot added integrated and removed ready rfr labels Nov 27, 2020
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@openjdk openjdk bot commented Nov 27, 2020

@TobiHartmann Pushed as commit 41ee0c8.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

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