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

[Roland Westrelin]

Hi Richard,

> 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

The bug is not visible.

> 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.

Keeping the original control would seem like the best fix. What error do
you get with it? Maybe keeping the cloned load's memory unchanged helps?

Roland.