On Sat, 1 Apr 2023 07:44:25 GMT, Quan Anh Mai <qa...@openjdk.org> wrote:
>> `Vector::slice` is a method at the top-level class of the Vector API that
>> concatenates the 2 inputs into an intermediate composite and extracts a
>> window equal to the size of the inputs into the result. It is used in vector
>> conversion methods where the part number is not 0 to slice the parts to the
>> correct positions. Slicing is also used in text processing such as utf8 and
>> utf16 validation. x86 starting from SSSE3 has `palignr` which does vector
>> slicing very efficiently. As a result, I think it is beneficial to add a C2
>> node for this operation as well as intrinsify `Vector::slice` method.
>>
>> A slice is currently implemented as
>> `v2.rearrange(iota).blend(v1.rearrange(iota), blendMask)` which requires
>> preparation of the index vector and the blending mask. Even with the
>> preparations being hoisted out of the loops, microbenchmarks show
>> improvement using the slice instrinsics. Some have tremendous increases in
>> throughput due to the limitation that a mask of length 2 cannot currently be
>> intrinsified, leading to falling back to the Java implementations.
>>
>> Please take a look and have some reviews. Thank you very much.
>
> Quan Anh Mai has updated the pull request with a new target base due to a
> merge or a rebase. The pull request now contains ten commits:
>
> - instruction asserts
> - Merge branch 'master' into sliceIntrinsics
> - add comments explaining anonymous classes
> - address reviews
> - sse2, increase warmup
> - aesthetic
> - optimise 64B
> - add jmh
> - vector slice intrinsics
src/hotspot/share/opto/vectorIntrinsics.cpp line 1935:
> 1933: return false; // should be primitive type
> 1934: }
> 1935: BasicType elem_bt = elem_type->basic_type();
Code style: It's better to add a blank line between different blocks.
src/hotspot/share/opto/vectorIntrinsics.cpp line 1941:
> 1939: if (C->print_intrinsics()) {
> 1940: tty->print_cr(" ** not supported: arity=2 op=slice vlen=%d
> etype=%s ismask=notused",
> 1941: num_elem, type2name(elem_bt));
`ismask=notused` could be removed. We used `ismask` in other intrinsics to
print whether it is a vector mask operation instead of vector class.
src/hotspot/share/opto/vectorIntrinsics.cpp line 1954:
> 1952: if (v1 == NULL || v2 == NULL) {
> 1953: return false; // operand unboxing failed
> 1954: }
Suggest to reorder line-1950 and the if-statement in line-1952. And then we
doesn't need too more spaces in the variable definition `Node* v1 =
unbox_vector(xxx)`. Besides, could we rename variable `o` to `index` or
`origin` ? I know you'v used `origin` at the begin, maybe we can rename it to
`origin_type`. I see the similari name style in
`inline_vector_frombits_coerced`.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/12909#discussion_r1156645453
PR Review Comment: https://git.openjdk.org/jdk/pull/12909#discussion_r1156646311
PR Review Comment: https://git.openjdk.org/jdk/pull/12909#discussion_r1156653402
