RFR: JDK-8238851: Shenandoah: C1: Resolve into registers of correct type

[Roman Kennke]

>> In ShBSC1::ensure_in_register() we are blindly creating registers of
>> type T_OBJECT, even though in some cases we actually need T_ADDRESS.
>> This blows up when we verify oop registers: when the argument is of type
>> T_OBJECT we perform extra checks that fail when the value in register is
>> not actually an object.
>>
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8238851
>> Webrev:
>> http://cr.openjdk.java.net/~rkennke/JDK-8238851/webrev.01/
>> Testing: the provided testcase passes now. hotspot_gc_shenandoah
> 
> This path probably needs adjustment too:
> 
>  167 #ifdef AARCH64
>  168       // AArch64 expects double-size register.
>  169       obj_reg = gen->new_pointer_register();
>  170 #else

The provided test passes on aarch64 without any additional changes.

I tried removing the block, hoping that the suggested change does
perhaps make it unnecessary, but no. It's still needed.

Further suggestions welcome. This whole thing kinda smells.

Roman