[PATCH 0/1] RISC-V: Fix canonical extension order (K and J)

[PATCH 0/1] RISC-V: Fix canonical extension order (K and J)

[Tsukasa OI]

This commit fixes canonical extension order...
from: "J" -> "K"
to  : "K" -> "J"
as per the RISC-V ISA Manual draft-20210402-1271737 or later.

This bug in the GNU Binutils is currently harmless because neither J nor
Zj* extensions are implemented.  Intention of this commit is for future-
proofness.

References:
<https://github.com/riscv/riscv-isa-manual/commit/1271737463c04cacd98320d820a38f66d1c87dae>
<https://github.com/riscv/riscv-isa-manual/releases/tag/draft-20210402-1271737>




Tsukasa OI (1):
  RISC-V: Fix canonical extension order (K and J)

 bfd/elfxx-riscv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


base-commit: b8e92c571baed4e794bd62b7bf417fa8bbaf5c95
-- 
2.32.0

[PATCH 1/1] RISC-V: Fix canonical extension order (K and J)

[Tsukasa OI]

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};
-- 
2.32.0

Re: [PATCH 1/1] RISC-V: Fix canonical extension order (K and J)

[Palmer Dabbelt]

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?

Re: [PATCH 1/1] RISC-V: Fix canonical extension order (K and J)

[Palmer Dabbelt]

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.

Re: [PATCH 1/1] RISC-V: Fix canonical extension order (K and J)

[Nelson Chu]

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.

Re: [PATCH 1/1] RISC-V: Fix canonical extension order (K and J)

[Tsukasa OI]

On 2022/05/19 12:40, Nelson Chu wrote:
> Seems like gcc and llvm have already committed this patch, so LGTM, committed.

Sorry, the same change is applied to LLVM but not yet on GCC (because I
forgot to add "Signed-off-by" line).  I sent PATCH v2 to gcc-patches
today so that would be okay.  On PATCH v2, I made the same change to
gcc/config/riscv/arch-canonicalize script (not just
gcc/common/config/riscv/riscv-common.cc).

<https://gcc.gnu.org/pipermail/gcc-patches/2022-May/595373.html>

Thanks,
Tsukasa

> 
> 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.
>