May RTX code grow faster than machine mode ? Since RTX code grows target independent wheras machine mode grows target dependent.
In the future, we may easily have more and more targets that some target may have a lot of machine mode. Maybe Richard Sandiford suggestion is a good idea to fix it? Thanks for all comments. juzhe.zh...@rivai.ai From: Jakub Jelinek Date: 2023-04-11 17:59 To: juzhe.zhong; Jeff Law; gcc-patches; kito.cheng; palmer; rguenther; richard.sandiford Subject: Re: [PATCH] machine_mode type size: Extend enum size from 8-bit to 16-bit 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
