[PATCH 5/8] ntdll: Add detection for PF_SSE_DAZ_MODE_AVAILABLE

[James Eder]

Gah... hit the wrong reply button so here we go again for some.

On Sun, Oct 21, 2012 at 10:06 AM, Joris Huizer <joris_huizer at yahoo.com> wrote:
> On 10/21/2012 05:49 PM, James Eder wrote:
>>
>> On Sat, Oct 20, 2012 at 7:06 PM, Chris Robinson <chris.kcat at gmail.com>
>> wrote:
>>>
>>> On 10/20/2012 05:40 PM, James Eder wrote:
>>>>
>>>> +    /* Intel says we need a zeroed 16-byte aligned buffer */
>>>> +    char buffer[512 + 16];
>>>> +    XMM_SAVE_AREA32 *state = (XMM_SAVE_AREA32 *)(((ULONG_PTR)buffer +
>>>> 15)
>>>> & ~15);
>>>> +    memset(buffer, 0, sizeof(buffer));
>>>> +
>>>> +    __asm__ __volatile__( "fxsave %0" : "=m" (*state) : "m" (*state) );
>>>
>>>
>>> Wouldn't this be simpler?
>>>
>>> DECLSPEC_ALIGN(16) XMM_SAVE_AREA32 state;
>>> memset(state, 0, sizeof(state));
>>> __asm__ __volatile__("fxsave %0" : "=m" (*&state) : "m" (*&state));
>>>
>>> May also want to make sure the two structs are packed.
>>>
>>>
>> I used  that alignment method because I saw it done that way other
>> places in Wine.  I figured there must have been a good reason for
>> doing it that way (issue with some build environments?) but perhaps
>> I'm being paranoid.
>>
>>
> I would think the construct is necessary when allocating memory (the
> allocation functions don't allow to require a certain alignment as far as I
> know)
> That might be where you saw this being done?
>
>

I was going off of save_fpux in dlls/ntdll/signal_i386.c:

static inline void save_fpux( CONTEXT *context )
{
#ifdef __GNUC__
    /* we have to enforce alignment by hand */
    char buffer[sizeof(XMM_SAVE_AREA32) + 16];
    XMM_SAVE_AREA32 *state = (XMM_SAVE_AREA32 *)(((ULONG_PTR)buffer +
15) & ~15);

    __asm__ __volatile__( "fxsave %0" : "=m" (*state) );
    context->ContextFlags |= CONTEXT_EXTENDED_REGISTERS;
    memcpy( context->ExtendedRegisters, state, sizeof(*state) );
#endif
}

-- 
Jim