[vectorIntrinsics] RFR: Improve mask reduction operations on AVX [v4]

[Mai Đặng Quân Anh]

On Wed, 17 Nov 2021 01:13:13 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

>> Mai Đặng Quân Anh has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   use duplicate dst instead of noreg, use lzcnt for hardwares support it
>
> src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 4058:
> 
>> 4056: void C2_MacroAssembler::vector_mask_operation(int opc, Register dst, KRegister mask,
>> 4057:                                               int masklen, int masksize, int vec_enc) {
>> 4058:   assert(VM_Version::supports_bmi1(), "Strange hardware");
> 
> Also need to check for supports_lzcnt().

We have separate checks for all `popcnt`, `lzcnt` and `tzcnt`, do you think the function should verify or just let the assembler throw after?

> src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 4148:
> 
>> 4146:       break;
>> 4147:     case Op_VectorMaskLastTrue:
>> 4148:       if (VM_Version::supports_bmi1()) {
> 
> This should be supports_lzcnt().

Oh right, thanks for noticing.

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PR: https://git.openjdk.java.net/panama-vector/pull/158