[aarch64-port-dev ] Is this a bug in C2?

[Roland Westrelin]

> We've recently been bitten by a JDK8 AArch64 back-end bug where
> constants out of the 0-31 range were matched by int shift patterns. I
> am surprised to see this: isn't C2 supposed to normalize shifts earlier
> in processing? We can fix it in the back end, but I'm wondering if we
> should. Thanks.

That came up before:

https://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2011-March/004944.html

(for a review related to arm32).

"I am concern about masking during ideal transformation. It affects all
platforms and you will convert a negative value to positive which may
produce a different result since it may affect some ideal
transformations. I would suggest to do it in .ad file."

https://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2011-March/004954.html

Roland.