2 ms·

No, I don't think it really makes sense for LLVM to mainline an architecture no one can use. I doubt they'll be on board with this.

verbatim 11y ago
It's not exactly unprecedented. GCC supports mmix, which hardware doesn't even exist for. (An educational platform from TAOCP.) https://gcc.gnu.org/backends.html https://gcc.gnu.org/backends.html
- iainmerrick 11y ago
  MMIX is fully documented, though. Being an educational platform is a valid reason to be supported.
- cmrx64 11y ago
  "Only has simulators" is very different from "nobody can use". MMIX has value.
- FullyFunctional 11y ago
  The difference between hardware and software is getting fuzzy (Transmeta, NVIDIA Denver, ...), but there's at least one (admittedly terrible) FPGA implementation of a subset of MMIX large enough to execute small graphical demos: https://github.com/tommythorn/fpgammix https://github.com/tommythorn/fpgammix
kenferry 11y ago
Looks like there's consensus to accept it as an "experimental" backend. I think that means the code is in tree, but other people changing LLVM aren't obligated to keep it working. It may be accepted as a full backend in the future, but that discussion is deferred since people are happy with it being experimental for now.
jakejake 11y ago
Ordinarily I'd agree with you. Except the tradeoff of having Google's other contributions to the main branch is probably worth it for a little bit of code that isn't harming anyone else. It's perhaps not fair, but just a reality that a company like Google has a lot to offer so they can sometimes get special treatment.
DannyBee 11y ago
GCC has done it for years. For LLVM mainline, often for small and simple architectures, the people contributing to mainline is much more valuable than the cost of having to make mechanical API changes in that backend when codegen api's are changed. (Once you have > ~5 backends, which LLVM does the cost of doing the latter just doesn't really change much). If you want to build a real community, turning away contributions likely to lead to an overall net positive for the community tends not to be a good approach :) (I await the arguments about corporations having no care about communities or whatever else)

verbatim 11y ago

It's not exactly unprecedented. GCC supports mmix, which hardware doesn't even exist for. (An educational platform from TAOCP.) https://gcc.gnu.org/backends.html https://gcc.gnu.org/backends.html

iainmerrick 11y ago
MMIX is fully documented, though. Being an educational platform is a valid reason to be supported.
cmrx64 11y ago
"Only has simulators" is very different from "nobody can use". MMIX has value.
FullyFunctional 11y ago
The difference between hardware and software is getting fuzzy (Transmeta, NVIDIA Denver, ...), but there's at least one (admittedly terrible) FPGA implementation of a subset of MMIX large enough to execute small graphical demos: https://github.com/tommythorn/fpgammix https://github.com/tommythorn/fpgammix

kenferry 11y ago

Looks like there's consensus to accept it as an "experimental" backend. I think that means the code is in tree, but other people changing LLVM aren't obligated to keep it working. It may be accepted as a full backend in the future, but that discussion is deferred since people are happy with it being experimental for now.

jakejake 11y ago

Ordinarily I'd agree with you. Except the tradeoff of having Google's other contributions to the main branch is probably worth it for a little bit of code that isn't harming anyone else. It's perhaps not fair, but just a reality that a company like Google has a lot to offer so they can sometimes get special treatment.

DannyBee 11y ago

GCC has done it for years. For LLVM mainline, often for small and simple architectures, the people contributing to mainline is much more valuable than the cost of having to make mechanical API changes in that backend when codegen api's are changed. (Once you have > ~5 backends, which LLVM does the cost of doing the latter just doesn't really change much). If you want to build a real community, turning away contributions likely to lead to an overall net positive for the community tends not to be a good approach :) (I await the arguments about corporations having no care about communities or whatever else)