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

[Vladimir Kozlov]

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
>>>>>
>>>