RFR: 8262355: Support for AVX-512 opmask register allocation. [v8]

[Jatin Bhateja]

On Tue, 16 Mar 2021 12:55:53 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8262355: Removing object re-materialization handling for mask-generating nodes during de-opt, it will be added separately.
>
> src/hotspot/share/opto/chaitin.cpp line 922:
> 
>> 920:           break;
>> 921:         case Op_RegVMask:
>> 922:           lrg.set_num_regs(RegMask::SlotsPerRegVMask);
> 
> Add `assert(Matcher::has_predicated_vectors(), "...")` here?

This will interfere with non-AVX512 targets, since some of instruction patterns have kReg temporary operands which will still be allocated but not JITed.

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PR: https://git.openjdk.java.net/jdk/pull/2768