[cairo] Problem compiling pixman-sse.c under Win32, blame it on MSVC !!

Vladimir Vukicevic vladimir at pobox.com
Fri Aug 8 18:43:16 PDT 2008 

No worries, thanks for taking a look!  If the pixman-sse.c you  
attached is good to go, I can push it upstream if you'd like (with  
Soeren's permission -- not sure if you have commit access).

     - Vlad

On Aug 8, 2008, at 3:23 PM, André Tupinambá wrote:

> Hi Vlad,
>
> Well I know, I'm little late ;)
> Sometimes I get so busy (job + free-lances) to work with pixman, but I
> finnished the tests.
>
> The perf tests ran ok, so we can use this modifications, but I found
> some bugs in the implementation. See the pixman-sse.c file in attach.
>
> Regards,
>
> André Tupinambá
>
>
> On Thu, Aug 7, 2008 at 1:55 PM, Vladimir Vukicevic  
> <vladimir at pobox.com> wrote:
>>
>> Hey Andre,
>>
>> Have you had a chance to take a look at this yet?  I'd like to get  
>> the speed
>> boost on win32 at least, still have some stack alignment issues to  
>> fix on
>> our end for linux.
>>
>>   - Vlad
>>
>> On Jul 21, 2008, at 6:48 PM, André Tupinambá wrote:
>>
>>> Yes, It's a really possible, but I'll test it first and check the
>>> generated assembly (in GCC and MSVC).
>>>
>>> If we had some slowdowns or poor compiler optimization, I will try  
>>> to
>>> change the inline functions to defines.
>>>
>>> Regards,
>>>
>>> André Tupinambá
>>>
>>>
>>> On Mon, Jul 21, 2008 at 10:05 PM, Rodrigo Kumpera  
>>> <kumpera at gmail.com>
>>> wrote:
>>>>
>>>> Since most of these functions force inlining, argument passing by  
>>>> pointer
>>>> or
>>>> by value
>>>> should not matter, modulo compiler inability to do the right thing.
>>>>
>>>> I think that there are no issues from changing some args from  
>>>> values to
>>>> regs
>>>> as long as GCC still manages to generate decent code. From what I  
>>>> recall,
>>>> this is not
>>>> the case and some reasonable recent version of it should do the  
>>>> trick.
>>>>
>>>> Frédéric, do you mind testing that for gcc?
>>>>
>>>> Thanks,
>>>> Rodrigo
>>>>
>>>> On Mon, Jul 21, 2008 at 6:19 AM, Antoine Azar <cairo at antoineazar.com 
>>>> >
>>>> wrote:
>>>>>
>>>>> Yep, I've tried everything on my side (playing with compiler  
>>>>> switches,
>>>>> setting the function parameters as const references, wrapping in
>>>>> structs,
>>>>> changing stack size, etc) and didn't have more luck than Fred.
>>>>>
>>>>> VC++ always borks starting the fourth __m128i parameter only.  
>>>>> The three
>>>>> first ones are always ok. It seems this is a limitation of VC++,  
>>>>> that
>>>>> it'll
>>>>> only handle a "pass by register" of up to three SSE intrinsics,  
>>>>> and not
>>>>> one
>>>>> more.
>>>>>
>>>>> I don't think sending pointers would be much of an issue: this is
>>>>> already
>>>>> done at many other places in the code, and it'll avoid the  
>>>>> overhead of
>>>>> passing by value 16 byte data structures.
>>>>> Otherwise, we can try rewriting functions so they always use at  
>>>>> most 3
>>>>> SSE
>>>>> intrinsics that are passed by value, but that might be a pain.
>>>>>
>>>>> I'd be curious to see how the Intel Compiler handles this.
>>>>>
>>>>> Antoine
>>>>>
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: cairo-bounces at cairographics.org
>>>>>> [mailto:cairo-bounces at cairographics.org] On Behalf Of Frédéric  
>>>>>> Plourde
>>>>>> Sent: Sunday, July 20, 2008 10:03 PM
>>>>>> To: cairo at cairographics.org
>>>>>> Subject: [cairo] Problem compiling pixman-sse.c under
>>>>>> Win32,blame it on MSVC !!
>>>>>>
>>>>>> Hi !
>>>>>>
>>>>>> Vlad had emailled me with this problem compiling pixman
>>>>>> sith SSE2 stuff enabled.
>>>>>> In fact, here are the errors that we got :
>>>>>>
>>>>>> pixman-sse.c
>>>>>> pixman-sse.c(142) : error C2719: 'xmm3': formal parameter with
>>>>>> __declspec(align('16')) won't be aligned
>>>>>> pixman-sse.c(195) : error C2719: 'alphaHi': formal parameter with
>>>>>> __declspec(align('16')) won't be aligned
>>>>>> pixman-sse.c(210) : error C2719: 'alphaDstHi': formal parameter  
>>>>>> with
>>>>>> __declspec(align('16')) won't be aligned
>>>>>> pixman-sse.c(210) : error C2719: 'dstLo': formal parameter with
>>>>>> __declspec(align('16')) won't be aligned
>>>>>> pixman-sse.c(210) : error C2719: 'dstHi': formal parameter with
>>>>>> __declspec(align('16')) won't be aligned
>>>>>> pixman-sse.c(210) : error C2719: 'alphaSrcLo': formal parameter  
>>>>>> with
>>>>>> __declspec(align('16')) won't be aligned
>>>>>> pixman-sse.c(210) : error C2719: 'alphaSrcHi': formal parameter  
>>>>>> with
>>>>>> __declspec(align('16')) won't be aligned
>>>>>> pixman-sse.c(246) : error C2719: 'alphaHi': formal parameter with
>>>>>> __declspec(align('16')) won't be aligned
>>>>>> pixman-sse.c(276) : error C2719: 'alphaHi': formal parameter with
>>>>>> __declspec(align('16')) won't be aligned
>>>>>> pixman-sse.c(276) : error C2719: 'maskLo': formal parameter with
>>>>>> __declspec(align('16')) won't be aligned
>>>>>> pixman-sse.c(276) : error C2719: 'maskHi': formal parameter with
>>>>>> __declspec(align('16')) won't be aligned
>>>>>> pixman-sse.c(290) : warning C4133: 'function' : incompatible
>>>>>> types - from '__m128i *' to 'const char *'
>>>>>> pixman-sse.c(296) : warning C4133: 'function' : incompatible
>>>>>> types - from '__m128i *' to 'const char *'
>>>>>> pixman-sse.c(371) : error C2719: 'alphaSrc': formal parameter  
>>>>>> with
>>>>>> __declspec(align('8')) won't be aligned
>>>>>> pixman-sse.c(398) : error C2719: 'dst': formal parameter with
>>>>>> __declspec(align('8')) won't be aligned
>>>>>> pixman-sse.c(4432) : error C2275: '__m128i' : illegal use of
>>>>>> this type as an expression
>>>>>>      D:\msvs8\VC\INCLUDE\emmintrin.h(45) : see declaration
>>>>>> of '__m128i'
>>>>>> pixman-sse.c(4432) : error C2146: syntax error : missing ';'
>>>>>> before identifier 'xmm0'
>>>>>> pixman-sse.c(4432) : error C2065: 'xmm0' : undeclared identifier
>>>>>> pixman-sse.c(4432) : error C2065: 'xmm1' : undeclared identifier
>>>>>> pixman-sse.c(4432) : error C2065: 'xmm2' : undeclared identifier
>>>>>> pixman-sse.c(4432) : error C2065: 'xmm3' : undeclared identifier
>>>>>> pixman-sse.c(4434) : error C2440: '=' : cannot convert from
>>>>>> '__m128i' to 'int'
>>>>>> pixman-sse.c(4435) : error C2440: '=' : cannot convert from
>>>>>> '__m128i' to 'int'
>>>>>> pixman-sse.c(4436) : error C2440: '=' : cannot convert from
>>>>>> '__m128i' to 'int'
>>>>>> pixman-sse.c(4437) : error C2440: '=' : cannot convert from
>>>>>> '__m128i' to 'int'
>>>>>> pixman-sse.c(4439) : error C2440: 'function' : cannot convert
>>>>>> from 'int'
>>>>>> to '__m128i'
>>>>>> pixman-sse.c(4439) : warning C4024: 'save128Aligned' :
>>>>>> different types for formal and actual parameter 2
>>>>>> pixman-sse.c(4440) : error C2440: 'function' : cannot convert
>>>>>> from 'int'
>>>>>> to '__m128i'
>>>>>> pixman-sse.c(4440) : warning C4024: 'save128Aligned' :
>>>>>> different types for formal and actual parameter 2
>>>>>> pixman-sse.c(4441) : error C2440: 'function' : cannot convert
>>>>>> from 'int'
>>>>>> to '__m128i'
>>>>>> pixman-sse.c(4441) : warning C4024: 'save128Aligned' :
>>>>>> different types for formal and actual parameter 2
>>>>>> pixman-sse.c(4442) : error C2440: 'function' : cannot convert
>>>>>> from 'int'
>>>>>> to '__m128i'
>>>>>> pixman-sse.c(4442) : warning C4024: 'save128Aligned' :
>>>>>> different types for formal and actual parameter 2
>>>>>>
>>>>>>
>>>>>> We found the following :
>>>>>>
>>>>>>
>>>>>> for every C2719 errors, the solution is to avoid passing
>>>>>> __m128i values directly, because MSVC just doesn't allow
>>>>>> function parameters to be of types declared with the
>>>>>> "__declspec(align('#'))" modifier (this is the case of
>>>>>> __m128i). See:
>>>>>> http://msdn.microsoft.com/en-us/library/373ak2y1(VS.80).aspx
>>>>>>
>>>>>> More problematic is the behaviour of MSVC under these
>>>>>> assumptions... in fact, try removing ONLY the xmm3 function
>>>>>> parameter at line #142 in pixman-sse.c  (and by commenting
>>>>>> references to xmm3 inside the function, of course), it will
>>>>>> compile. (!!).  I've went through different forums for
>>>>>> developpers and it seems there are still some bugs with those
>>>>>> intrinsics in MSVC8. Very dissapointing!
>>>>>>
>>>>>> So my recommandation to misters Tupinamba and Kumpera would
>>>>>> be to pass POINTERS to those function parameters instead...
>>>>>> as :
>>>>>>
>>>>>> static inline __m128i
>>>>>> pack565_4x128_128 (__m128i *xmm0,  __m128i *xmm1,  __m128i
>>>>>> *xmm2, __m128i *xmm3) {
>>>>>> __m128i lo, hi;
>>>>>>
>>>>>> lo = _mm_packus_epi16 (pack565_2x128_128 ( *xmm0, *xmm1 ),
>>>>>> _mm_setzero_si128 ());
>>>>>> hi = _mm_packus_epi16 (_mm_setzero_si128 (),
>>>>>> pack565_2x128_128 ( *xmm2, *xmm3 ));
>>>>>>
>>>>>> return _mm_or_si128 (lo, hi);
>>>>>> }
>>>>>>
>>>>>> compiles perfectly.
>>>>>> However, this would maybe imply significant impacts on
>>>>>> performance... it should be addressed and profiled..
>>>>>>
>>>>>>
>>>>>> ******
>>>>>> Besides, for the C2275 error, it's even more embarassing for
>>>>>> microsoft... it's another case of MSVC being very capricious.
>>>>>> In some cases, with aligned variables, MSVC doesn't allow us
>>>>>> to declare
>>>>>> those variable in the middle of the function... We then need
>>>>>> to move the
>>>>>> declaration earlier.
>>>>>> see, at line 4432,
>>>>>>
>>>>>>         __m128i xmm0, xmm1, xmm2, xmm3; needs to be moved up a
>>>>>> little... as :
>>>>>>
>>>>>> while (w >= 64)
>>>>>>     {
>>>>>>     __m128i xmm0, xmm1, xmm2, xmm3;
>>>>>>
>>>>>>         /* 128 bytes ahead */
>>>>>>         cachePrefetch (((__m128i*)s) + 8);
>>>>>>         cachePrefetch (((__m128i*)d) + 8);
>>>>>>
>>>>>> compiles now...
>>>>>> ****************
>>>>>>
>>>>>> So here it is... a patch with those changes in pixman-sse.c
>>>>>> I'd like you guys (especcially André) to look that over and
>>>>>> tell me what
>>>>>> you think.  It's a first draft, but it compiles under all 3
>>>>>> major platforms.
>>>>>>
>>>>>> Best,
>>>>>> -fred-
>>>>>>
>>>>>
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>>>>
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>>
> <pixman-sse.c>

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