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

[陈嘉炜]

Hi Nelson,

Thank you for the check, if we undo with this patch, here comes another unexpected results same as you mentioned:

riscv64-unknown-elf-as -misa-spec=20191213 -march=rv64i_zbb_zknd empty.s -o empty.o
Assembler messages:
Error: rv64i_zicsr_zifencei_zbb_zknd: prefixed ISA extension `zknd' is not in expected order.  It must come before `zbb'

I think that zb* should goes before zk*, so I change the order at first patch to make 'zb' before 'zk'. Sorry for that I missed zicsr， zifencei and don't check it.

What should the right order if we have a string both contain 'zb', 'zk' even 'zp', 'zv' like  -march=rv64i_zicsr_zifencei_zbb_zknd?


"Nelson Chu" <nelson.chu@sifive.com>写道：
> 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
</jiawei@iscas.ac.cn>