Re: [PATCH] math: x86: Remove extra '%' on FP_INIT_ROUNDMODE inline asm

[Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>]

On 01/09/22 11:51, H.J. Lu wrote:
> On Thu, Sep 1, 2022 at 6:01 AM Adhemerval Zanella Netto
> <adhemerval.zanella@linaro.org> wrote:
>>
>>
>>
>> On 31/08/22 16:33, H.J. Lu wrote:
>>> On Wed, Aug 31, 2022 at 11:16 AM Adhemerval Zanella via Libc-alpha
>>> <libc-alpha@sourceware.org> wrote:
>>>>
>>>> Checked on x86_64-linux-gnu.
>>>> ---
>>>>  sysdeps/x86/fpu/sfp-machine.h | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/sysdeps/x86/fpu/sfp-machine.h b/sysdeps/x86/fpu/sfp-machine.h
>>>> index 5892f4f5fe..1cacdb4ebd 100644
>>>> --- a/sysdeps/x86/fpu/sfp-machine.h
>>>> +++ b/sysdeps/x86/fpu/sfp-machine.h
>>>> @@ -41,7 +41,7 @@ typedef unsigned int UTItype __attribute__ ((mode (TI)));
>>>>
>>>>  # define FP_INIT_ROUNDMODE                                     \
>>>>    do {                                                         \
>>>> -    __asm__ __volatile__ ("%vstmxcsr\t%0" : "=m" (_fcw));      \
>>>> +    __asm__ __volatile__ ("vstmxcsr\t%0" : "=m" (_fcw));       \
>>>>    } while (0)
>>>>  #else
>>>>  # define _FP_W_TYPE_SIZE       32
>>>> --
>>>> 2.34.1
>>>>
>>>
>>> The intention was to generate stmxcsr with SSE and vstmxcsr with
>>> AVX.  I think we should define a special prefix, like AVX_INSN_PREFIX,
>>> which is 'v' if __AVX__ is defined and empty if __AVX__ isn't defined.
>>>
>>
>> Right, I was not aware of it.  Is is documented on gcc inline assembly
> 
> I need to take a look.

Thanks.

> 
>> manual somewhere (I could not find it)? In any case I will follow your
>> suggestion.
> 
> There is no need for it.  %v is handled by compiler with an operand.

Not by all compilers in fact, that's why I proposing the change.