RFR: 8287794: Reverse*VNode::Identity problem [v2]

[Jatin Bhateja]

On Mon, 25 Jul 2022 06:13:09 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> No, since the flag Predicated_with_blend is set over nodes if operation itself is predicated, here both ReverseBytesV nodes are non-predicated ones and this check is part of identity routines of reverse* operations.
>
> Oh, right! What I mean is the case like:
> 
> VectorBlend (ReverseBytesV X) (ReverseBytesV (ReverseBytesV X)) MASK   ==> VectorBlend (ReverseBytesV X) X MASK 
> 
> which is the same case with `test_reversebytes_long_transform2` for non-predicated systems.

As already [discussed](https://github.com/openjdk/panama-vector/pull/182#discussion_r927419799),  we can handle this as a separate PR along with other complimentary operations. This bug fix patch is fixing a specific issue.

>> CPU features list is populated during VM startup, this list is later ON queried by applyIfCPUFeature during IR validations, I do not think UseSVE is a valid flag for X86, 
>> 
>> 
>> SPROMPT>java -XX:UseSVE=0
>> Unrecognized VM option 'UseSVE=0'
>> Error: Could not create the Java Virtual Machine.
>> Error: A fatal exception has occurred. Program will exit.
>> SPROMPT>lscpu
>> Architecture:                    x86_64
>> CPU op-mode(s):                  32-bit, 64-bit
>> Byte Order:                      Little Endian
>> Address sizes:                   46 bits physical, 48 bits virtual
>> CPU(s):                          72
>> On-line CPU(s) list:             0-71
>> Thread(s) per core:              2
>> Core(s) per socket:              18
>> Socket(s):                       2
>> NUMA node(s):                    2
>> Vendor ID:                       GenuineIntel
>> CPU family:                      6
>> Model:                           85
>> Model name:                      Intel(R) Xeon(R) Gold 6139 CPU @ 2.30GHz
>
> Yes, it's invalid on x86. So maybe you could add the limitation to the "requires", but seems this could make the codes complex.

Correct.

-------------

PR: https://git.openjdk.org/jdk/pull/9623