RFR: 8319111: Mismatched MemorySegment heap access is not consistently intrinsified [v2]

[Jatin Bhateja]

On Thu, 30 Nov 2023 22:57:29 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

>> src/hotspot/share/opto/vectorIntrinsics.cpp line 1244:
>> 
>>> 1242: 
>>> 1243:   int mem_num_elem = mismatched_ms ? num_elem * type2aelembytes(elem_bt) : num_elem;
>>> 1244:   BasicType mem_elem_bt = mismatched_ms ? T_BYTE : elem_bt;
>> 
>> Shouldn't the mem_elem_bt come from arr_type->elem()->array_element_basic_type()?
>> Also the mem_num_elem be calculated accordingly?
>
> The non masked load/store is doing that but the masked load/store is using T_BYTE.

Yes, that's what the intent is, for masked versions we operate at byte granularity to support widening and narrowing case e.g. loading masked float vector from a double memory segment, mask bit is in accordance with float type, but cannot be directly reflected over double lanes.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16888#discussion_r1411776496