Which components of GCC are broken for Darwin [PPC] and which are feasible (and more desirable) to be fixed?

[barracuda156]

@iains I would like to have an overall idea of what in GCC is broken for Darwin in general and PPC specifically – and of those, what is broken irredeemably and what is broken simply because no one had time or bothered to fix it.
Question with practical relevance: if I can do something to improve upon current state of things, I will try (within feasibility for myself, of course).

Some things which we already know are:

1. driver-driver has to be fixed to enable FAT building binaries (all Darwin) – tagging @devernay & @kencu here.
2. gccgo is broken (all Darwin) – maybe @catap can contribute here, conditional on having time to. Fixing should be feasible: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=46986
3. dlang/libphobos is broken (all Darwin?). No idea if fixable. Ancient version of gcd existed for Darwin PPC, based on gcc-4.2: https://gdcmac.sourceforge.net
4. gccrust – status unknown, possibly builds: PowerPC support? Rust-GCC/gccrs#1573
5. libquadmath – unsupported on 32-bit, possibly may build on ppc64 (?).
6. IEEE arithmetic in libgfortran – missing for PPC, should be restorable, since Apple fenv.h seems to have needed stuff: Support for ieee_arithmetic in gcc12-gfortran for Darwin PPC? #40 (reply in thread)