[NFCI][msan] Precommit tests for AVX-VNNI (#153135)
The tests largely cover AVX-VNNI (Vector Neural Network Instructions):
- vpdpbusd, vpdpbusds
- vpdpwssd, vpdpwssds
AVX-VNNI-INT8:
- vpdpbssd, vpdpbssds
- vpdpbsud, vpdpbsuds
- vpdpbuud, vpdpbuuds
AVX-VNNI-INT16:
- vpdpwsud, vpdpwsuds
- vpdpwusd, vpdpwusds
- vpdpwuud, vpdpwuuds
These instructions are currently heuristically handled (by OR'ing
together the vectors). This is incorrect because:
1) multiplication by a zero should result in an initialized value 2) the
addition is horizontal (within vectors, not "vertically" between
vectors).
Future work can improve the instrumentation by applying the updated
handleVectorPmaddIntrinsic() from
https://github.com/llvm/llvm-project/pull/152941
