[Bug target/87391] [RISCV] -march=rv32i -mabi=ilp32e is erroneously accepted

[asb at lowrisc dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87391

--- Comment #4 from Alex Bradbury <asb at lowrisc dot org> ---
(In reply to Jim Wilson from comment #2)
> One can specify an architecture with FP registers, and an ABI that does not
> use the FP registers.  By the same token, it is reasonable to expect that
> one should be able to specify an rv32i architecture and use an rv32e ABI
> with it.  In both cases, the unused registers all become call clobbered (aka
> caller saved).

It's a reasonable expectation, but the ABI docs explicitly state it is an
illegal combination. It would make sense to propose a change to the ABI if you
want to support -mabi=ilp32e -march=rv32i.