RFR: 8267212: test/jdk/java/util/Collections/FindSubList.java intermittent crash with "no reachable node should have no use"

[Hui Shi]

On Mon, 17 May 2021 11:44:48 GMT, Hui Shi <hshi at openjdk.org> wrote:

> … crash with "no reachable node should have no use"
> 
> Please help reivew this fix.
> 
> StrIntrinsicNode::Ideal uses Node::set_req to replace memory input, old memory input might have 0 use, but not added into PhaseGVN worklist. Using set_req_X to ensure add 0 out old memory input node into PhaseGVN worklist.
> 
> Find other two similar problemtic code in LoadNode::Ideal.
> 
> Tier1/2/3 pass with release/fastdebug build.
> test/jdk/java/util/Collections/FindSubList.java doesn't fail in 100 runs (before fix 2/3 failure in 10 runs).

pre-submit tests  have been passed https://github.com/huishi-hs/jdk/actions/runs/849445331 

checking here still not completed. ignore.

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PR: https://git.openjdk.java.net/jdk/pull/4055