[vectorIntrinsics+mask] RFR: 8264563: Add masked vector intrinsics for binary/store operations [v8]

[Paul Sandoz]

On Wed, 28 Apr 2021 06:47:55 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> Hi, this is the basic masking support PR for Vector API mask operations on platforms like SVE/AVX-512. The main codes are from [1], which contains:
>> 
>> - The predicate register allocation for Arm SVE, and vector mask type definition.
>> - The basic optimization for parts of the mask operations with masking feature. It contains:   
>>  
>>   1. Vector API java implementation changes for masked binary/store.
>>   2. C2 compiler mid-end changes, including new vector intrinsics implementation and mask IRs.
>> 
>> Note that for easier discussion, this PR only provides the changes for limited masked operations (e.g. binary/store) and the mask generations (e.g. load/compare/maskAll). We will continue working on the following missing parts:
>> 
>> - Mask support for other operations (unary,ternary,reduction,load,etc.)
>> - More mask IRs implementation (and/or/xor, toVector, allTrue, anyTrue, trueCount, eq, etc)
>> - Vector boxing/unboxing support for mask type (deoptimization support for predicate registers)
>> 
>> Also note that this PR doesn't contain any backend implementations. So the blend pattern will be generated as before. Regarding to the AArch64 SVE backend support, we will create a separate PR based on this one in future.
>>   
>> [1] https://github.com/openjdk/panama-vector/pull/40
>> 
>> See more details from:
>> http://cr.openjdk.java.net/~xgong/rfr/mask/Vector%20API%20masking%20support%20proposal%20for%20Arm%20SVE.pdf
>> http://cr.openjdk.java.net/~xgong/rfr/mask/VectorAPI%20masking%20support.pdf
>> 
>> Any suggestions and discussions are welcome! Thanks a lot!
>
> Xiaohong Gong has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Separate lanewiseTemplate for masked and non-masked operations

I left a few minor comments that could be addressed after integration of this PR.

src/jdk.incubator.vector/share/classes/jdk/incubator/vector/X-Vector.java.template line 651:

> 649:     $abstractvectortype$ lanewiseTemplate(VectorOperators.Binary op,
> 650:                                           Class<? extends VectorMask<$Boxtype$>> maskClass,
> 651:                                           Vector<$Boxtype$> v) {

Suggestion:

    $abstractvectortype$ lanewiseTemplate(VectorOperators.Binary op,
                                          Vector<$Boxtype$> v) {

Remove unused argument by passing `null` to the intrinsic for the `maskClass` argument?

src/jdk.incubator.vector/share/classes/jdk/incubator/vector/X-Vector.java.template line 4247:

> 4245:     <M extends VectorMask<$Boxtype$>>
> 4246:     void intoArray0Template(Class<M> maskClass, $type$[] a, int offset, M m) {
> 4247:         $Type$Species vsp = vspecies();

Need `m.check(maskClass, this)`?

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PR: https://git.openjdk.java.net/panama-vector/pull/57