RFR: 8288043: Optimize FP to word/sub-word integral type conversion on X86 AVX2 platforms [v5]

[Jatin Bhateja]

On Mon, 19 Sep 2022 21:28:58 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8288043: Extending exiting regressions with more cases.
>
> src/hotspot/cpu/x86/matcher_x86.hpp line 193:
> 
>> 191:       case Op_VectorCastF2X: // fall through
>> 192:       case Op_VectorCastD2X: {
>> 193:         return is_subword_type(ety) ? 75 : 70;
> 
> Add comment here and in other cases explaining numbers. Is it size of instructions or elements or something?

Value now matches the one for RoundV[FD] IR nodes, currently, its a rudimentary heuristic based on emitted code size for complex IR nodes used by unroll policy.

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PR: https://git.openjdk.org/jdk/pull/9748