RFR: 8257772: Vectorizing clear memory operation using AVX-512 masked operations [v4]

[Tobias Hartmann]

On Mon, 14 Dec 2020 04:57:29 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> src/hotspot/cpu/x86/macroAssembler_x86.cpp line 4937:
>> 
>>> 4935:   // base - start address, qword aligned.
>>> 4936:   Label L_zero_64_bytes, L_loop, L_sloop, L_tail, L_end;
>>> 4937:   bool use64byteVector = MaxVectorSize == 64 && AVX3Threshold == 0;
>> 
>> The comment for `AVX3Threshold` says:
>>   "Minimum array size in bytes to use AVX512 intrinsics"
>>   "for copy, inflate and fill. When this value is set as zero"
>>   "compare operations can also use AVX512 intrinsics.")
>> 
>> Should we mention clear memory there as well?
>
> Hi Nils, comments already cover "fill", clear memory is semantically equivalent to fill by zero.

Okay, that's fine.

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

PR: https://git.openjdk.java.net/jdk/pull/1631