"Pengxuan Zheng (QUIC)" <quic_pzh...@quicinc.com> writes:
>> On Thu, Sep 12, 2024 at 2:53 AM Pengxuan Zheng
>> <quic_pzh...@quicinc.com> wrote:
>> >
>> > SVE's INDEX instruction can be used to populate vectors by values
>> > starting from "base" and incremented by "step" for each subsequent
>> > value. We can take advantage of it to generate vector constants if
>> > TARGET_SVE is available and the base and step values are within [-16, 15].
>>
>> Are there multiplication by or addition of scalar immediate instructions to
>> enhance this with two-instruction sequences?
>
> No, Richard, I can't think of any equivalent two-instruction sequences.
There are some. E.g.:
{ 16, 17, 18, 19, ... }
could be:
index z0.b, #0, #1
add z0.b, z0.b, #16
or, alternatively:
mov w0, #16
index z0.b, w0, #1
But these cases are less obviously a win, so I think it's ok to handle
single instructions only for now.
The patch is ok for trunk, thanks, but:
>> > @@ -22991,7 +22991,7 @@ aarch64_simd_valid_immediate (rtx op,
>> simd_immediate_info *info,
>> > if (CONST_VECTOR_P (op)
>> > && CONST_VECTOR_DUPLICATE_P (op))
>> > n_elts = CONST_VECTOR_NPATTERNS (op);
>> > - else if ((vec_flags & VEC_SVE_DATA)
>> > + else if (which == AARCH64_CHECK_MOV && TARGET_SVE
>> > && const_vec_series_p (op, &base, &step))
...the convention is to have one && condition per line if the whole
expression doesn't fit on a single line:
else if (which == AARCH64_CHECK_MOV
&& TARGET_SVE
&& const_vec_series_p (op, &base, &step))
Richard
