RFC: 8262295: C2: Out-of-Bounds Array Load from Clone Source

[Reingruber, Richard]

Hi,

I've been working on a fix for

JDK-8262295: C2: Out-of-Bounds Array Load from Clone Source
https://bugs.openjdk.java.net/browse/JDK-8262295

Now I'm not sure if the fix I found (compile time range check) is a good one.

I have created a draft PR with the fix not yet ready for proper review:

https://github.com/openjdk/jdk/pull/2708

Please let me know what you think and if this is the right approach.

My first attempt was to keep the original control for the cloned node in
LoadNode::can_see_arraycopy_value() but this seemd to confuse loop
optimizations. At least the test compiler/escapeAnalysis/TestMissingAntiDependency.java
failed with that change.

Another potential fix could be adding a runtime range check.

What do you think?

Thanks, Richard.