[PATCH] RISC-V: Add an implicit dependency for Zawrs

[Xiao Zeng]

2024-10-08 14:18  Andrew Waterman <andrew@sifive.com> wrote:
>
>But that's not what the normative text in the spec says!  
Yes.
> Using non-normative notes to infer dependencies between extensions is
>dangerous territory.
>
>It is true that the WRS instructions aren't useful without the LR
>instruction, 
Perhaps the spec should specify more clearly: 
"Implicit dependencies should not be inferred from any direct explanation"

>but it is also true that Binutils shouldn't be inventing
>extension dependencies that aren't normatively justified. 
Yes, thank you for your suggestion.

I will wait for the spec to clarify this.
>
>
>On Mon, Oct 7, 2024 at 11:07 PM Xiao Zeng <zengxiao@eswincomputing.com> wrote:
>>
>> There is a description in <https://github.com/riscv/riscv-isa-manual/blob/main/src/zawrs.adoc>:
>>
>> "The instructions in the Zawrs extension are only useful in conjunction
>> with the LR instruction, which is provided by the Zalrsc component
>> of the A extension."
>>
>> It can be concluded that: zawrs -> zalrsc.
>>
>> The implementation in gcc is as follows:
>> <https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=c01e3aaae79ecd439ad35063db3dee9775f3aefa>
>>
>> bfd/ChangeLog:
>>
>>         * elfxx-riscv.c: zawrs -> zalrsc.
>>
>> gas/ChangeLog:
>>
>>         * testsuite/gas/riscv/imply.d: Add implicit dependency
>>         testing for zawrs.
>>         * testsuite/gas/riscv/imply.s: Updated.
>>
>> Signed-off-by: Xiao Zeng <zengxiao@eswincomputing.com>
>> ---
>>  bfd/elfxx-riscv.c               | 1 +
>>  gas/testsuite/gas/riscv/imply.d | 1 +
>>  gas/testsuite/gas/riscv/imply.s | 1 +
>>  3 files changed, 3 insertions(+)
>>
>> diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
>> index 4b48d8ee9f0..b7b4d95195e 100644
>> --- a/bfd/elfxx-riscv.c
>> +++ b/bfd/elfxx-riscv.c
>> @@ -1184,6 +1184,7 @@ static struct riscv_implicit_subset riscv_implicit_subsets[] =
>>
>>    {"zabha", "+zaamo", check_implicit_always},
>>    {"zacas", "+zaamo", check_implicit_always},
>> +  {"zawrs", "+zalrsc", check_implicit_always},
>>    {"a", "+zaamo,+zalrsc", check_implicit_always},
>>
>>    {"xsfvcp", "+zve32x", check_implicit_always},
>> diff --git a/gas/testsuite/gas/riscv/imply.d b/gas/testsuite/gas/riscv/imply.d
>> index 26eff8c650a..64dda77a9f8 100644
>> --- a/gas/testsuite/gas/riscv/imply.d
>> +++ b/gas/testsuite/gas/riscv/imply.d
>> @@ -17,6 +17,7 @@ SYMBOL TABLE:
>>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_m2p0_zmmul1p0
>>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_zaamo1p0_zabha1p0
>>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_zaamo1p0_zacas1p0
>> +[0-9a-f]+ l       .text        0+000 \$xrv32i2p1_zalrsc1p0_zawrs1p0
>>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_a2p1_zaamo1p0_zalrsc1p0
>>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_zicsr2p0_zve32x1p0_zvl32b1p0_xsfvcp1p0
>>  [0-9a-f]+ l       .text        0+000 \$xrv32i2p1_f2p2_d2p2_v1p0_zicsr2p0_zve32f1p0_zve32x1p0_zve64d1p0_zve64f1p0_zve64x1p0_zvl128b1p0_zvl32b1p0_zvl64b1p0
>> diff --git a/gas/testsuite/gas/riscv/imply.s b/gas/testsuite/gas/riscv/imply.s
>> index dabb08d8c8b..c831ea63f04 100644
>> --- a/gas/testsuite/gas/riscv/imply.s
>> +++ b/gas/testsuite/gas/riscv/imply.s
>> @@ -18,6 +18,7 @@ imply m
>>
>>  imply zabha
>>  imply zacas
>> +imply zawrs
>>  imply a
>>
>>  imply xsfvcp
>> --
>> 2.17.1
>>
Thanks
Xiao Zeng