Is anyone working on -mtune/-march/-mcpu support for Hazard3/RP2350 in GCC?

[palmer-dabbelt]

A few of us were talking on IRC about tunings, which led me to poking around and finding this -- I hadn't realized the RP2350 had it's own uarch, sorry. I was just wondering if anyone was planning on sending patches for GCC. Specifically it looks like the Xh3bextm extension could hook into some actual codegen, and the tune/cpu structs would make life a little easier for users to target.

Also: thanks a ton for the datasheet, it's super detailed. Having the exact tapeout RTL and targeted spec versions makes life a lot easier for us SW people ;)

Having the datasheet should make it fairly straight-forward to do this, but I wanted to check and see if anyone was already planning on doing so.

[Wren6991]

Hi Palmer, I'm not planning GCC support. To be honest it's a little out of my expertise, and this processor is a one-man band (no support from Raspberry Pi).

I think building a scheduler model might make for a nice example port, since the timing characteristics are fairly simple and well-specified (both by datasheet and RTL). I've had reasonably good code gen from GCC just with -mbranch-cost=1, but it would be a nice datapoint to see how much is left on the table without a proper model, especially as LLVM have indicated they're inclined not to merge a scheduler model since it bloats their backend and they are always multi-target.

Some LLVM folks are already looking at instruction selection support for Xh3bextm -- it might be worth paging @lenary.