Re: [PATCH] Correct cpu_flags for CPU_ANY_AVX512BW_FLAGS

[Jan Beulich <jbeulich@suse.com>]

On 23.06.2022 18:04, H.J. Lu wrote:
> On Thu, Jun 23, 2022 at 1:08 AM Cui, Lili <lili.cui@intel.com> wrote:
>>
>>
>>
>>> -----Original Message-----
>>> From: Jan Beulich <jbeulich@suse.com>
>>> Sent: Thursday, June 23, 2022 3:30 PM
>>> To: Cui, Lili <lili.cui@intel.com>
>>> Cc: binutils@sourceware.org; hjl.tools@gmail.com
>>> Subject: Re: [PATCH] Correct cpu_flags for CPU_ANY_AVX512BW_FLAGS
>>>
>>> On 23.06.2022 09:14, Cui,Lili wrote:
>>>> This patch is to correct cpu_flags for CPU_ANY_AVX512BW_FLAGS.
>>>> Make check-gas is ok.
>>>> Ok for master?
>>>>
>>>> Thanks,
>>>> Lili.
>>>>
>>>> Change it from "CPU_ANY_AVX512_FP16_FLAGS" to "CpuAVX512_FP16"
>>>
>>> You don't say what's wrong with what there is right now. I for one think what
>>> we have is correct: If one disables BW, _all_ its dependents should be
>>> disabled as well, which transitively means all dependents of FP16.
>>>
>> Hi Jan,
>> Agree with that " If one disables BW, _all_ its dependents should be disabled as well ".
>> I saw the form of "CPU_ANY_AVX512F_FLAGS" today, and to be consistent with it, I thought "CPU_ANY_AVX512_FP16_FLAGS" was wrong at that time. But after reading your email, I found "CPU_ANY_AVX512F_FLAGS" to be the only one that uses cpu_flags instead of CPU_ANY* .
>>
>> { "CPU_ANY_AVX512F_FLAGS",
>> "CpuAVX512F|CpuAVX512CD|CpuAVX512ER|CpuAVX512PF|CpuAVX512DQ|CPU_ANY_AVX512BW_FLAGS|CpuAVX512VL|CpuAVX512IFMA|CpuAVX512VBMI|CpuAVX512_4FMAPS|CpuAVX512_4VNNIW|CpuAVX512_VPOPCNTDQ|CpuAVX512_VBMI2|CpuAVX512_VNNI|CpuAVX512_BITALG|CpuAVX512_BF16|CpuAVX512_VP2INTERSECT" },
>>
>> Regards,
>> Lili.
>>
>>> Jan
>>>
>>>> opcodes/
>>>>
>>>>     * i386-gen.c (cpu_flag_init): Change cpu_flags of
>>>>     CPU_ANY_AVX512BW_FLAGS.
>>>> ---
>>>>  opcodes/i386-gen.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/opcodes/i386-gen.c b/opcodes/i386-gen.c index
>>>> d18a7d2754..5dc224efdb 100644
>>>> --- a/opcodes/i386-gen.c
>>>> +++ b/opcodes/i386-gen.c
>>>> @@ -382,7 +382,7 @@ static initializer cpu_flag_init[] =
>>>>    { "CPU_ANY_AVX512DQ_FLAGS",
>>>>      "CpuAVX512DQ" },
>>>>    { "CPU_ANY_AVX512BW_FLAGS",
>>>> -    "CpuAVX512BW|CPU_ANY_AVX512_FP16_FLAGS" },
>>>> +    "CpuAVX512BW|CpuAVX512_FP16" },
>>>>    { "CPU_ANY_AVX512VL_FLAGS",
>>>>      "CpuAVX512VL" },
>>>>    { "CPU_ANY_AVX512IFMA_FLAGS",
>>
> 
> Since CPU_ANY_AVX512_FP16_FLAGS is the same as CpuAVX512_FP16,
> this change is nop.  On the other hand, CPU_ANY shouldn't be used to define
> another CPU_ANY.

Why? Imo that's exactly how it should be, as long as the purpose of
CPU_ANY_* is the use for processing of negative .arch directives.

Jan