On 11/04/2023 10:46, Richard Sandiford via Gcc-patches wrote:
<juzhe.zh...@rivai.ai> writes:
ARM SVE has：svint8_t, svint8x2_t, svint8x3_t, svint8x4_t
As far as I known, they don't have tuple type for partial vector.
Yeah, there are no separate types for partial vectors, but there
are separate modes. E.g. VNx2QI is a partial vector of QIs,
with each QI stored in a 64-bit container.
I agree with all the comments about the danger of growing the number of
modes too much. But it looks like rtx_def should be easy to rearrange.
Unless I'm missing something, there are less than 256 rtx codes at
present. So one simple option would be to make the code 8 bits and
the machine_mode 16 bits (and swap them, so that they stay well-aligned
wrt their size).
That of course would create new problem if we want more than 256 codes
in future. But then there would be the option of a non-power-of-2
split (12/12 or whatever). Also, it's possible to multiplex operations
into a single code by adding an extra operand, whereas it's harder to
multiplex modes.
Thanks,
Richard
The rtx code and mode are both accessed quite frequently, making them
non-native machine sizes might have impact on the performance of
accessing the fields.
