[PATCH 1/4] RISC-V: Fix order check when use 'z*' sub-extensions

[Nelson Chu]

Hi jiawei,

On Tue, Nov 2, 2021 at 5:44 PM jiawei <jiawei@iscas.ac.cn> wrote:
>
> ---
>  bfd/elfxx-riscv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
> index cdb4fa0996a..0d8fc755b5c 100644
> --- a/bfd/elfxx-riscv.c
> +++ b/bfd/elfxx-riscv.c
> @@ -1333,7 +1333,7 @@ riscv_compare_subsets (const char *subset1, const char *subset2)
>           order1 = riscv_ext_order[(*++subset1 - 'a')];
>           order2 = riscv_ext_order[(*++subset2 - 'a')];
>           if (order1 != order2)
> -           return order1 - order2;
> +           return order2 - order1;
>         }
>        return strcasecmp (++subset1, ++subset2);
>      }
> --
> 2.25.1
>

After I apply this change, I get the unexpected results as follows,

nelson@LAPTOP-QFSGI1F2:~/test$
~/binutils-dev/build-linux64-upstream/build-install/bin/riscv64-unknown-linux-gnu-as
-misa-spec=20191213 -march=rv64i_zicsr_zifencei_zbb empty.s -o empty.o
Assembler messages:
Error: rv64i_zicsr_zifencei_zbb: prefixed ISA extension `zbb' is not
in expected order.  It must come before `zifencei'

BTW, the expected result is as follows, before applying this patch,

nelson@LAPTOP-QFSGI1F2:~/test$
~/binutils-dev/build-linux64-upstream/build-install/bin/riscv64-unknown-linux-gnu-as
-misa-spec=20191213 -march=rv64i_zicsr_zifencei_zbb empty.s -o empty.o
nelson@LAPTOP-QFSGI1F2:~/test$
~/binutils-dev/build-linux64-upstream/build-install/bin/riscv64-unknown-linux-gnu-readelf
-A empty.o                  Attribute Section: riscv
File Attributes
  Tag_RISCV_arch: "rv64i2p1_zicsr2p0_zifencei2p0_zbb1p0"

Could I ask what issues or cases you want to resolve originally, so
that you need to change this?

Thanks
Nelson