The combination of Google Guice 5.1.0 and the Azul Prime JVM is causing a VM crash. I've reached out to Azul support about this and they believe that the root cause is that the class com.google.inject.internal.aop.HiddenClassDefiner treats a klassOop as though it were an Object.

HiddenClassDefiner defines TRUSTED_LOOKUP_BASE like this:

private static final Object TRUSTED_LOOKUP_BASE;

And its value is obtained like this:

Method baseMethod = unsafeType.getMethod("staticFieldBase", Field.class);
TRUSTED_LOOKUP_BASE = baseMethod.invoke(THE_UNSAFE, trustedLookupField);

So TRUSTED_LOOKUP_BASE, nominally a private static final Object, is obtained by calling Unsafe.staticFieldBase() via reflection.

Here's how it's used in Guice:

public Class<?> define(Class<?> hostClass, byte[] bytecode) throws Exception {
    Lookup trustedLookup =
        (Lookup) GET_OBJECT_METHOD.invoke(THE_UNSAFE, TRUSTED_LOOKUP_BASE, TRUSTED_LOOKUP_OFFSET);

Which calls Unsafe.getObject((Object)TRUSTED_LOOKUP_BASE, (long)TRUSTED_LOOKUP_OFFSET).

This use of TRUSTED_LOOKUP_BASE ignores the admonitions of Unsafe.staticFieldBase(), which says the value is not guaranteed to be a real Object:

/**
 * Reports the location of a given static field, in conjunction with {@link
 * #staticFieldOffset}.
 * <p>Fetch the base "Object", if any, with which static fields of the
 * given class can be accessed via methods like {@link #getInt(Object,
 * long)}.  This value may be null.  This value may refer to an object
 * which is a "cookie", not guaranteed to be a real Object, and it should
 * not be used in any way except as argument to the get and put routines in
 * this class.
 */
@ForceInline
public Object staticFieldBase(Field f) {

Now, a lot of reflection code is generated on the fly at runtime and inlined. I'm also told the Prime VM emits a checkcast bytecode, which does what it says and checks the reference to be returned by getObject is, in fact, an Object, which a klassOop isn't. Hence the attempt to throw a ClassCastException in a place where the VM shouldn't.

Here is the hs_err file for the crash: hs_err_pid12.log.gz