RFR: 8173472: AArch64: C1 comparisons with null only use 32-bit instructions

[Roland Westrelin]

> Yesterday I found an absolute doozy of a bug: we're only comparing 32
> bits of an address with null.  So a couple of times in a billion, if
> the heap is in the right place and the moon is in the right phase, a
> null pointer comparison will result in a false positive.
>
> http://cr.openjdk.java.net/~aph/8173472-1/

I must be missing something. What's wrong with:

if (type2aelembytes(opr1->type()) <= 4)

?

Roland.