Hello, I am new to OpenJDK development and I want to propose changes to
Class#enumConstants from
Class#getEnumConstants()/Class#getSharedEnumConstants().
Currently consider the following example:
```java
enum E {
A, B, C
}
E[] values = E.values();
E[] constants = E.class.getEnumConstants();
assert Arrays.equals(values, constants);
```
These methods provide an equal array of values, but they are treated
differently. This is because the _constants_ stored by Class#enumConstants
are non final and declared volatile. So C2 can't trust this call. Consider
if I only wanted to access the value from an offset from these arrays.
```java
E value = values[0];
E constant = constants[0];
assert value == constant;
```
_constant_ would never be folded but _value_ would be.
So I propose the addition of @Stable annotation added to
Class#enumConstants so _constant_ can be folded by C2. This is not a
trivial change as it requires changing the data race to abide by @Stable.
Could I be sponsored for this change (JBS issue as well)?
A future proposal would be adding @Stable to Class#enumConstantDirectory,
though that can be a seperate enhancement as that might require changing of
the data structure to allow folding. Let me know if it should be combined
as the Stable annotation itself would be implemented in a similar way for
both.
Thanks,
Ryan Hallock
