RFR: Clean up ZLoadBarrierStubC1 tmp register allocation

[Erik Österlund]

Hi Per,

Looks good.

Thanks,
/Erik

On 2018-05-08 11:31, Per Liden wrote:
> This patch moves some of the register allocation logic in the C1 load 
> barrier stub to shared code instead of being platform specific. 
> There's also some cosmetic touch-ups of this code.
>
> http://cr.openjdk.java.net/~pliden/zgc/c1_load_barrier_stub_tmp_alloc/webrev.0 
>
>
> /Per