On Wed, 17 Jun 2026 09:27:19 GMT, Ferenc Rakoczi <[email protected]> wrote:
>> Addendum:
>>
>> There is no need to include the static assert for even length in the
>> overloaded variant of `vs_st2_post` i.e. you can just use this:
>>
>>
>> // store 2 x N-vector sequences interleaved into 2 * N quadword
>> // memory locations via the address supplied in base using
>> // post-increment addressing.
>> template<int N>
>> void vs_st2_post(const VSeq<N>& v1, const VSeq<N>& v2,
>> Assembler::SIMD_Arrangement T, Register base) {
>> for (int i = 0; i < N; i++) {
>> __ st2(v1[i], v2[i], T, __ post(base, 32));
>> }
>> }```
>
> This idea sounds great, but, unfortunately, in st2(v1, v2, T, post(base, 32))
> it is required that the register index of v2 be one more than that of v1, so
> I just added a comment at the consuming part.
Ah, yes. That's a shame as saving the data in canonical order would be much
better. We could salvage this by redeclaring the sequences so that adjacent
elements A[i] and D[i] are adjacent vector registers.
VSeq<4> A(16, 2);
VSeq<4> D(17, 2);
VSeq<4> B(24);
VSeq<4> C(28);
or equivalently
VSeq<8> A_D(16);
VSeq<4> A = vs_even(A_D);
VSeq<4> D = vs_odd(A_D);
VSeq<4> B(24);
VSeq<4> C(28);
but then a reader needs to work out why this is being done.
I'll settle for your comment that restates the permuted layout just prior to
the ldrs.
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PR Review Comment: https://git.openjdk.org/jdk/pull/30941#discussion_r3427880307
