[vectorIntrinsics+mask] RFR: 8266287: Basic mask IR implementation for the Vector API masking feature support

[Jatin Bhateja]

On Thu, 6 May 2021 10:12:08 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

> Based on [1], this patch adds the C2 compiler mid-end changes for the masking feature support. It mainly contains:
>  1) Generation of the mask IRs for vector mask, including:
>     - Mask generations, e.g. load/compare/maskAll
>     - Mask operations, e.g. and/or/xor
>  2) Conversions between vector and mask after loading mask values from memory and before storing mask values into memory
>  3) Generation of the vector IRs which need the mask value as the control
>     - The mask value is appended to the original vector node's input list
> 
> With this change, the bottom type of the vector mask will be set to `"TypeVectMask"` if the platform supports the masking feature and the backend implementations are added.
> 
> Note that this patch only contains the compiler mid-end changes. The backend implementations for SVE/AVX-512 will be in the
> followed-up patches.
> 
> [1] https://github.com/openjdk/panama-vector/pull/57

src/hotspot/share/opto/vectorIntrinsics.cpp line 84:

> 82:   assert(check_vbox(vbox_type), "");
> 83:   const TypeVect* vt = is_vector_mask(vbox_type->klass()) ?
> 84:                        TypeVect::makemask(elem_bt, num_elem) : TypeVect::make(elem_bt, num_elem);

Box type which is an envelope type should still be the same e.g. Int256VectorMask. Value contained in the Masked Box should be of type vectmask.

src/hotspot/share/opto/vectorIntrinsics.cpp line 102:

> 100:                        TypeVect::makemask(elem_bt, num_elem) : TypeVect::make(elem_bt, num_elem);
> 101:   Node* unbox = gvn().transform(new VectorUnboxNode(C, vt, v, merged_memory(), shuffle_to_vector));
> 102:   return unbox;

Same as above.

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PR: https://git.openjdk.java.net/panama-vector/pull/78