On Fri, 11 Sep 2026 22:28:43 GMT, Sandhya Viswanathan
<[email protected]> wrote:
>> Jatin Bhateja has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> Regenerating jdk.incubator.vector sources post merge
>
> src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 7134:
>
>> 7132: // res[255:128] = {src2[127:0] , src1[255:128]} >> SHIFT
>> 7133: vperm2f128(dst, src1, src2, 0x21);
>> 7134: vpalignr(dst, dst, src1, origin, Assembler::AVX_256bit);
>
> For origin==8, it is better to use:
> vshufps(dst, src1, dst, 0x4E, Assembler::AVX_256bit);
> instead of vpalignr.
Done
> src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 7148:
>
>> 7146: // res[255:128] = {src2[255:128] , src2[127:0]} >> (SHIFT - 16)
>> 7147: vperm2f128(dst, src1, src2, 0x21);
>> 7148: vpalignr(dst, src2, dst, origin - 16, Assembler::AVX_256bit);
>
> For origin==24, it is better to use:
> vshufps(dst, dst, src2, 0x4E, Assembler::AVX_256bit);
> instead of vpalignr.
Done
> src/hotspot/share/opto/vectorIntrinsics.cpp line 1841:
>
>> 1839: Node* origin_node = gvn().intcon(origin->get_con() *
>> type2aelembytes(elem_bt));
>> 1840: const TypeVect* vector_type = TypeVect::make(elem_bt, num_elem);
>> 1841: Node* operation = gvn().transform(trace_vector(new
>> VectorSliceNode(v1, v2, origin_node, vector_type)));
>
> For subword vectors of length > 16 with mid range byte origin (16 < byte
> origin < 48) there seems to be a regression. This is due to having three
> shuffle ops (valignd+valignd+valignr), we could instead rewrite this case
> with VectorLoadConst followed by SelectFromTwoVector where supported. The
> compiler would then hoist the VectorLoadConst above the loop and it would be
> just vpermi2b/w inside the loop.
>
> Node* iota = gvn().transform(new
> VectorLoadConstNode(gvn().makecon(TypeInt::ZERO), vector_type));
> Node* bcast =
> gvn().transform(VectorNode::scalar2vector(gvn().intcon(origin->get_con()),
> num_elem, elem_bt));
> Node* index = gvn().transform(VectorNode::make(add_vopc, iota, bcast,
> vector_type));
> operation = gvn().transform(trace_vector(new SelectFromTwoVectorNode(index,
> v1, v2, vector_type)));
Addressed
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/24104#discussion_r4012360474
PR Review Comment: https://git.openjdk.org/jdk/pull/24104#discussion_r4012360861
PR Review Comment: https://git.openjdk.org/jdk/pull/24104#discussion_r4012362183
