> How does it fail? Is it related to m32c, ehm, interesting > architectural features (24 bits addresses and only 2 address > registers IIRC)?
I think so. The m32c family has such a non-orthogonal register set that there's a lot of small register classes. There are few cases where GENERAL_REGS is the right class for a given insn. GCC has always had a hard time doing register allocation and reload for this target, and IRA makes it just worse enough at it that some of the newlib sources can no longer be built. Note that m32c-elf is a standard newlib-sim target, so if anyone wants to play with it, it's easy enough to build and test as a cross-compiler.