On Tue, Apr 11, 2023 at 10:46:25AM +0100, Richard Sandiford wrote:
> 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.
We have 151 rtx codes if not a generator, 201 otherwise. That is closer to
the limit except for the RISCV proposed changes.
Jakub
