[12] RFR 8206895: aarch64: rework error-prone cmp instuction

[Boris Ulasevich]

I am not sure how to mark instruction deprecated. Why don't just remove 
it and update all the usage points? Here is the updated review:

http://cr.openjdk.java.net/~bulasevich/8206895/webrev.00

Boris

On 09.07.2018 17:50, Andrew Haley wrote:
> On 07/09/2018 03:31 PM, Boris Ulasevich wrote:
>> http://cr.openjdk.java.net/~bulasevich/8206895/webrev.00
>> https://bugs.openjdk.java.net/browse/JDK-8206895
>>
>> Byte form of cmp instruction was added. For bigger constants we are
>> supposed to state _imm12 postfix implicitly or use cmp(reg,reg,imm) macro.
> 
> I don't think that making cmp an alias for subs helps anyone:
> 
> +  inline void cmp(Register Rd, Register Rn, unsigned imm32)  { subs(Rd, Rn, imm32); }
> 
> I think the best suggestion was to make the 8-bit cmp the only form
> allowed, mark the larger cmp as deprecated, and force the user to use
> subs.  That would be easier to read than cmp_imm12().
>