RFR: 8308583: SIGSEGV in GraphKit::gen_checkcast

[Tobias Hartmann]

On Wed, 24 May 2023 12:31:37 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> At an `instanceof`, a node of type `bottom[int:>=0]` is checked to be of type `cc$Word` and on the success a `CheckCastPP` is inserted to change the node type. That `CheckCastPP` constant folds to `top` but the type check doesn't fold. The reason is that the type check loads the klass from the node with a `LoadNKlass` and the type of that node is `java/lang/Object`  when it should be `bottom[int:>=0]` but logic in `LoadNKlass::Value()` gets in the way.

Looks good to me.

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Marked as reviewed by thartmann (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14123#pullrequestreview-1443489618