[aarch64-port-dev ] RFR: 8131362: aarch64: C2 does not handle large stack offsets

[Andrew Haley]

On 17/07/15 10:29, Andrew Haley wrote:
> On 17/07/15 10:12, Edward Nevill wrote:
>> On Fri, 2015-07-17 at 10:01 +0100, Andrew Haley wrote:
>>> On 17/07/15 09:52, Edward Nevill wrote:
>>>>>> Should it be +8 instead of +4? Or these offsets are not in bytes?:
>>>>>>
>>>>>> +      unspill(rscratch1, true, src_offset);
>>>>>> +      spill(rscratch1, true, dst_offset);
>>>>>> +      unspill(rscratch1, true, src_offset+4);
>>>>>> +      spill(rscratch1, true, dst_offset+4);
>>>> Ouch! Good catch.
>>>>
>>>> New webrev.
>>>>
>>>> http://cr.openjdk.java.net/~enevill/8131362/webrev.03/
>>>
>>> I'm a bit more concerned that this did not fail in testing.  I guess
>>> there were no tests at all for stack-stack spills.
>>
>> Correct. And it would have to be a 128 bit vector stack-stack spill with
>> an offset >= 512. How would you even provoke such a thing.
> 
> With a highly-vectorizable test case with a zillion temporaries, I guess.

Thinking some more: I think I'd add some special code to test it all
once, then delete the special code.  If that's what it takes, there
isn't much choice.

Andrew.