[PATCH] RISC-V: Allow ISA subsets to be disabled

[Alex Bradbury]

On 30 March 2017 at 20:45, Palmer Dabbelt <palmer@dabbelt.com> wrote:
> Without this patch, passing "-march=rv64ic -march=rv64i" results in
> you getting a "RV64IC" toolchain, which isn't expected.
>
> gas/ChangeLog:
>
> 2017-03-30  Palmer Dabbelt  <palmer@dabbelt.com>
>
>        * config/tc-riscv.c (riscv_clear_subsets): New function.
>        (riscv_add_subset): Call riscv_clear_subsets and riscv_set_rvc to
>        clear RVC when it's been previously set.

For what it's worth, the current behaviour (i.e. the behaviour before
this patch) seems to be in line with other architectures. e.g. if I do
`gcc -march=native -march=generic` then the latter won't override the
former - at least as evidenced by `gcc -march=native -march=generic -E
-v - </dev/null`.

Best,

Alex