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

[Nils Eliasson]

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
>>