[aarch64-port-dev ] RFR: 8075930: AARCH64: Use FP Register in C2

[Dean Long]

On 4/24/2015 4:35 AM, Edward Nevill wrote:
>
>
> On 23 April 2015 at 20:01, Dean Long <dean.long at oracle.com 
> <mailto:dean.long at oracle.com>> wrote:
>
>
>     What happens at a safepoint polling point in a loop?  Will C2 try
>     to keep an oop value
>     in R29 live across the safepoint?  If so, I assume the oopmap
>     takes care of that case as
>     well.
>
>
> Yes. Here is an example of an OopMap at a safepoint in a loop
>
>    0x000003ff710efa1c: adrp      x10, 0x000003ff79830000
>                                                 ; OopMap{r14=Oop off=160}
>                                                 ;*goto
>                                                 ; - 
> MethodAtom::execute at 46 (line 35)
>                                                 ;   {poll}
>   0x000003ff710efa20: ldr       wzr, [x10]      ;*goto
>                                                 ; - 
> MethodAtom::execute at 46 (line 35)
>                                                 ;   {poll}
>   0x000003ff710efa24: ldr       w10, [x14,#16]
>   0x000003ff710efa28: cmp       w16, w10
>   0x000003ff710efa2c: b.ge <http://b.ge>      0x000003ff710efb74 ;*aload_0
>                                                 ; - 
> MethodAtom::execute at 12 (line 37)
>
> All the best,
> Ed.
>

I was expecting to see r29=Oop, but if it works for x86 I don't see why 
it wouldn't work for aarch64.

dl