RFR(S): 8213538: VM crashes when MaxVectorSize is set to 0, 1 or 2

[Tobias Hartmann]

Hi Nils,

looks good to me too.

Best regards,
Tobias

On 13.11.18 18:34, Vladimir Kozlov wrote:
> Good.
> 
> Thanks,
> Vladimir
> 
> On 11/13/18 9:27 AM, Nils Eliasson wrote:
>> Updated:
>>
>> http://cr.openjdk.java.net/~neliasso/8213538/webrev.03/
>>
>> Regards
>>
>> // Nils
>>
>> On 2018-11-13 17:55, Vladimir Kozlov wrote:
>>> You don't need max_max because the value reflect real max vector size supported by hardware. And
>>> we use this size to initialize a flag - only this initialization is related to flag. There for I
>>> asked "max_vector_size and min_vector_size" names.
>>>
>>> Thanks,
>>> Vladimir
>>>
>>> On 11/13/18 1:31 AM, Nils Eliasson wrote:
>>>> Hi,
>>>>
>>>> The flag name is MaxVectorSize - so then it becomes max_max_vector_size and min_max_vector_size
>>>> which is a bit hard to read. In this new rev I opted for max_MaxVectorSize and min_MaxVectorSize
>>>> to emphasize the relationship with the flag.
>>>>
>>>> I am all open to other suggestions.
>>>>
>>>> http://cr.openjdk.java.net/~neliasso/8213538/webrev.02
>>>>
>>>> Regards,
>>>> Nils
>>>>
>>>>
>>>> On 2018-11-12 19:18, Vladimir Kozlov wrote:
>>>>> Hi Nils,
>>>>>
>>>>> Fix and refactoring looks good.
>>>>>
>>>>> The only complain I have is names of locals. Can you use full names: max_vector_size and
>>>>> min_vector_size?
>>>>>
>>>>> Please, add testing results link to bug report.
>>>>>
>>>>> Thanks,
>>>>> Vladimir
>>>>>
>>>>> On 11/12/18 3:14 AM, Nils Eliasson wrote:
>>>>>> Hi,
>>>>>>
>>>>>> This patch add the requirement that MaxVectorSize must be at least 4 on x64.
>>>>>>
>>>>>> The background is that we crash in startup when testing when setting it to 0, 1 or 2. When
>>>>>> MaxVectorSize is less than 4, the XMM reg types won't be initialized, and then we crash in
>>>>>> intrinsics that unconditionally use XMM regs. Since SSE2 is the required minimum on x64, the
>>>>>> assumption that you can use XMM regs is always valid. This adds the requirement that
>>>>>> MaxVectorSize is at least 4.
>>>>>>
>>>>>> I had to do a little refactoring to make the code more readable, but the essence is the same.
>>>>>>
>>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8213538
>>>>>>
>>>>>> Webrev: http://cr.openjdk.java.net/~neliasso/8213538/webrev/
>>>>>>
>>>>>> Testing is running.
>>>>>>
>>>>>> Please review,
>>>>>>
>>>>>> // Nils
>>>>>>
>>>>