From: Nelson Chu <nelson.chu@sifive.com>
To: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Binutils <binutils@sourceware.org>
Subject: Re: [PATCH 1/1] RISC-V: Fix canonical extension order (K and J)
Date: Thu, 19 May 2022 11:40:49 +0800 [thread overview]
Message-ID: <CAJYME4HZhSZYbLDeX4jkciaFAff2fRRAKMB+mb-n=5ZC0EwWXQ@mail.gmail.com> (raw)
In-Reply-To: <mhng-11cb0b1b-822a-4c04-b1c3-2fe2b3666e24@palmer-mbp2014>
Seems like gcc and llvm have already committed this patch, so LGTM, committed.
Thanks
Nelson
On Mon, Apr 25, 2022 at 11:53 AM Palmer Dabbelt <palmer@dabbelt.com> wrote:
>
> On Mon, 28 Mar 2022 17:12:55 PDT (-0700), Palmer Dabbelt wrote:
> > On Mon, 28 Mar 2022 06:12:01 PDT (-0700), binutils@sourceware.org wrote:
> >> This commit fixes canonical extension order to follow the RISC-V ISA
> >> Manual draft-20210402-1271737 or later.
> >>
> >> bfd/ChangeLog:
> >>
> >> * elfxx-riscv.c (riscv_recognized_prefixed_ext): Fix "K" extension
> >> prefix to be placed before "J".
> >> ---
> >> 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 cb2cc146c04..1219a7b44d4 100644
> >> --- a/bfd/elfxx-riscv.c
> >> +++ b/bfd/elfxx-riscv.c
> >> @@ -1338,7 +1338,7 @@ riscv_recognized_prefixed_ext (const char *ext)
> >> }
> >>
> >> /* Canonical order for single letter extensions. */
> >> -static const char riscv_ext_canonical_order[] = "eigmafdqlcbjktpvn";
> >> +static const char riscv_ext_canonical_order[] = "eigmafdqlcbkjtpvn";
> >>
> >> /* Array is used to compare the orders of standard extensions quickly. */
> >> static int riscv_ext_order[26] = {0};
> >
> > Looks like this was just a bug in binutils: K went from being
> > unspecified to specified in 271737 ("Define canonical location of K
> > extension in ISA string"), thus it was never allowed at that other bit
> > position.
> >
> > It looks like GCC also has this wrong, which sort of doubles the
> > headache: now we've got this odd coupling between the GCC version and
> > binutils version. I'm not sure what the right thing is to do here:
> > certainly rejecting the valid ISA string should be fixed, but I think we
> > might need to accept the invalid one for compatibility reasons. That'll
> > be a headache to implement, though, so I'm not sure it's worth it.
> >
> > Maybe someone has a clever solution to this one?
>
> After seeing the GCC patch go by, I think the clever solution here is to
> just say that we never accepted any J stuff in the first place so it's
> not a compatibility break.
next prev parent reply other threads:[~2022-05-19 3:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-28 13:12 [PATCH 0/1] " Tsukasa OI
2022-03-28 13:12 ` [PATCH 1/1] " Tsukasa OI
2022-03-29 0:12 ` Palmer Dabbelt
2022-04-25 3:52 ` Palmer Dabbelt
2022-05-19 3:40 ` Nelson Chu [this message]
2022-05-22 9:35 ` Tsukasa OI
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