RFR: 8075930: AARCH64: Use FP Register in C2

[Andrew Haley]

On 25/03/15 14:08, Andrew Dinn wrote:
> On 25/03/15 13:28, Zoltán Majó wrote:
>> On 03/25/2015 02:02 PM, Edward Nevill wrote:
>>> The aarch64 C2 compiler makes no use of the FP register even though
>>> this register is saved on entry and restored on exit and is therefore
>>> always available for allocation.
>>
>> It seems to me that the C2 compiler currently saves the SP into FP on
>> method handle invokes. This functionality is encoded by
>> aarch64_enc_java_handle_call in aarch64.ad. C1 does the same (see usages
>> of FrameMap::method_handle_invoke_SP_save_opr()).
> 
> Yes, that's correct. aarch64_enc_java_handle relies on having FP
> available to save SP. So, it looks like this fix will break that.

I'm surprised it matters.  If FP is live around a handle call I would
have thought it would be spilled onto the stack.

Andrew.