On Tue, 24 Sep 2024 07:10:24 GMT, Jatin Bhateja <jbhat...@openjdk.org> wrote:
>> Hi All,
>>
>> As per the discussion on panama-dev mailing list[1], patch adds the support
>> for following new two vector permutation APIs.
>>
>>
>> Declaration:-
>> Vector<E>.selectFrom(Vector<E> v1, Vector<E> v2)
>>
>>
>> Semantics:-
>> Using index values stored in the lanes of "this" vector, assemble the
>> values stored in first (v1) and second (v2) vector arguments. Thus, first
>> and second vector serves as a table, whose elements are selected based on
>> index value vector. API is applicable to all integral and floating-point
>> types. The result of this operation is semantically equivalent to
>> expression v1.rearrange(this.toShuffle(), v2). Values held in index vector
>> lanes must lie within valid two vector index range [0, 2*VLEN) else an
>> IndexOutOfBoundException is thrown.
>>
>> Summary of changes:
>> - Java side implementation of new selectFrom API.
>> - C2 compiler IR and inline expander changes.
>> - In absence of direct two vector permutation instruction in target ISA, a
>> lowering transformation dismantles new IR into constituent IR supported by
>> target platforms.
>> - Optimized x86 backend implementation for AVX512 and legacy target.
>> - Function tests covering new API.
>>
>> JMH micro included with this patch shows around 10-15x gain over existing
>> rearrange API :-
>> Test System: Intel(R) Xeon(R) Platinum 8480+ [ Sapphire Rapids Server]
>>
>>
>> Benchmark (size) Mode Cnt
>> Score Error Units
>> SelectFromBenchmark.rearrangeFromByteVector 1024 thrpt 2 2041.762
>> ops/ms
>> SelectFromBenchmark.rearrangeFromByteVector 2048 thrpt 2 1028.550
>> ops/ms
>> SelectFromBenchmark.rearrangeFromIntVector 1024 thrpt 2 962.605
>> ops/ms
>> SelectFromBenchmark.rearrangeFromIntVector 2048 thrpt 2 479.004
>> ops/ms
>> SelectFromBenchmark.rearrangeFromLongVector 1024 thrpt 2 359.758
>> ops/ms
>> SelectFromBenchmark.rearrangeFromLongVector 2048 thrpt 2 178.192
>> ops/ms
>> SelectFromBenchmark.rearrangeFromShortVector 1024 thrpt 2 1463.459
>> ops/ms
>> SelectFromBenchmark.rearrangeFromShortVector 2048 thrpt 2 727.556
>> ops/ms
>> SelectFromBenchmark.selectFromByteVector 1024 thrpt 2 33254.830
>> ops/ms
>> SelectFromBenchmark.selectFromByteVector 2048 thrpt 2 17313.174
>> ops/ms
>> SelectFromBenchmark.selectFromIntVector 1024 thrpt 2 10756.804
>> ops/ms
>> S...
>
> Jatin Bhateja has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Handling NPOT vector length for AArch64 SVE with vector sizes varying b/w
> 128 and 2048 bits at 128 bit increments.
src/hotspot/share/opto/vectorIntrinsics.cpp line 2698:
> 2696: int cast_vopc = VectorCastNode::opcode(-1, elem_bt, true);
> 2697: if (is_floating_point_type(elem_bt)) {
> 2698: index_elem_bt = elem_bt == T_FLOAT ? T_INT : T_LONG;
index_elem_bt is already assigned at line 2676 and 2678 so this line could be
removed.
src/jdk.incubator.vector/share/classes/jdk/incubator/vector/ByteVector.java
line 551:
> 549: return ((ByteVector)src1).vectorFactory(res);
> 550: }
> 551:
This could instead be:
src1.rearrange(this.lanewise(VectorOperators.AND, 2 * VLENGTH -
1).toShuffle(), src2);
Or even simplified to:
src1.rearrange(this.toShuffle(), src2);
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/20508#discussion_r1777839817
PR Review Comment: https://git.openjdk.org/jdk/pull/20508#discussion_r1779722306
