[PATCH] RISC-V: Checking 'm' extension when using RVV.

[Jiawei]

在 2025/1/21 23:55, Christoph Müllner 写道:
> On Tue, Jan 21, 2025 at 4:23 PM Jiawei <jiawei@iscas.ac.cn> wrote:
>> This patch add a new extension check when using `v` extension, it
>> currently should also enable `m` extension to make sure vector length
>> caculate correct.
> How to trigger this incorrect calculation?
> Is there an example?

I found this commit in gcc refer to this, please check it:

https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=e589ffb6d78881572ddea21df0d9b6c2641d574d;hp=4cbbce045681c234387d8d56376ea179dc869229


BR,

Jiawei

>> bfd/ChangeLog:
>>
>>          * elfxx-riscv.c (riscv_parse_check_conflicts): New check.
>>
>> gas/ChangeLog:
>>
>>          * testsuite/gas/riscv/march-fail-rv64i_v.d: New test.
>>          * testsuite/gas/riscv/march-fail-rv64i_v.l: New test.
>>
>> ---
>>   bfd/elfxx-riscv.c                            | 10 +++++++++-
>>   gas/testsuite/gas/riscv/march-fail-rv64i_v.d |  4 ++++
>>   gas/testsuite/gas/riscv/march-fail-rv64i_v.l |  3 +++
>>   3 files changed, 16 insertions(+), 1 deletion(-)
>>   create mode 100644 gas/testsuite/gas/riscv/march-fail-rv64i_v.d
>>   create mode 100644 gas/testsuite/gas/riscv/march-fail-rv64i_v.l
>>
>> diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
>> index c9e4b03b17d..150838d3d24 100644
>> --- a/bfd/elfxx-riscv.c
>> +++ b/bfd/elfxx-riscv.c
>> @@ -2123,7 +2123,15 @@ riscv_parse_check_conflicts (riscv_parse_subset_t *rps)
>>          (_("`xtheadvector' is conflict with the `v' extension"));
>>         no_conflict = false;
>>       }
>> -
>> +  /* We might use a multiplication to calculate the scalable vector length at
>> +     runtime.  Therefore, require the M extension.  */
>> +  if (riscv_lookup_subset (rps->subset_list, "v", &subset)
>> +      && !riscv_lookup_subset (rps->subset_list, "m", &subset))
>> +    {
>> +      rps->error_handler
>> +       (_("Currently the 'v' implementation requires the 'm' extension"));
>> +      no_conflict = false;
>> +    }
>>     bool support_zve = false;
>>     bool support_zvl = false;
>>     riscv_subset_t *s = rps->subset_list->head;
>> diff --git a/gas/testsuite/gas/riscv/march-fail-rv64i_v.d b/gas/testsuite/gas/riscv/march-fail-rv64i_v.d
>> new file mode 100644
>> index 00000000000..4d14bb4f9a9
>> --- /dev/null
>> +++ b/gas/testsuite/gas/riscv/march-fail-rv64i_v.d
>> @@ -0,0 +1,4 @@
>> +#as: -march=rv64i_v
>> +#source: empty.s
>> +#error_output: march-fail-rv64i_v.l
>> +
>> diff --git a/gas/testsuite/gas/riscv/march-fail-rv64i_v.l b/gas/testsuite/gas/riscv/march-fail-rv64i_v.l
>> new file mode 100644
>> index 00000000000..5386a942ec5
>> --- /dev/null
>> +++ b/gas/testsuite/gas/riscv/march-fail-rv64i_v.l
>> @@ -0,0 +1,3 @@
>> +Assembler messages:
>> +Error: Currently the 'v' implementation requires the 'm' extension
>> +
>> --
>> 2.43.0
>>