[LLVMdev] [clang] SSE2 intrinsics (emmintrin.h): _mm_movpi64_pi64 should be _mm_movpi64_epi64?

[Alp Toker]

On 23/11/2013 13:29, Dimitry Andric wrote:
> On 01 Nov 2013, at 17:15, Alexey Dokuchaev <danfe at nsu.ru> wrote:
>> I've recently encountered a piece of code that uses some SSE2 intrinsics
>> and builds with gcc46, but not clang: clang can't find _mm_movpi64_epi64(),
>> while gcc46 defines it in its lib/gcc46/gcc/.../4.6.3/include/emmintrin.h:
>>
>>   extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
>>   _mm_movpi64_epi64 (__m64 __A)
>>   {
>>     return _mm_set_epi64 ((__m64)0LL, __A);
>>   }
>>
>>   extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
>>   _mm_set_epi64x (long long __q1, long long __q0)
>>   {
>>     return __extension__ (__m128i)(__v2di){ __q0, __q1 };
>>   }
>>
>> Now, Clang in /usr/include/clang/3.3/emmintrin.h defines similar function,
>> but without the `e', _mm_movpi64_pi64():
>>
>>   static __inline__ __m128i __attribute__((__always_inline__, __nodebug__))
>>   _mm_movpi64_pi64(__m64 __a)
>>   {
>>     return (__m128i){ (long long)__a, 0 };
>>   }
>>
>> Microsoft (http://msdn.microsoft.com/en-us/library/has3d153(v=vs.90).aspx)
>> defines these two:
>>
>>   _mm_movepi64_pi64		MOVDQ2Q			Move
>>   _mm_movpi64_epi64		MOVQ2DQ			Move
>>
>> That is:
>>
>>   __m64 _mm_movepi64_pi64 (__m128i a);
>>   MOVDQ2Q
>>   r0 := a0 ;
>>
>>   __m128i _mm_movpi64_epi64 (__m64 a);
>>   MOVDQ2Q
>>   r0 := a0 ; r1 := 0X0 ;
>>
>> Cf. Intel's manual [1]:
>>
>>   _mm_movepi64_pi64		Move			MOVDQ2Q
>>   _mm_movpi64_epi64		Move			MOVDQ2Q
>>
>>   __m64 _mm_movepi64_pi64(__m128i a)
>>   Returns the lower 64 bits of a as an __m64 type:	R0 := a0
>>
>>   __m128i _mm_movpi64_pi64(__m64 a)			<<< TYPO?!
>>   Moves the 64 bits of a to the lower 64 bits
>>   of the result, zeroing the upper bits:		R0 := a0, R1 = 0X0
>>
>> Assuming that both documents correctly assign instructions to function
>> names (bonus clue: it also makes them symmetrical), then _mm_movpi64_pi64
>> is indeed a typo and Clang's header is wrong, while GCC's is correct: it
>> should read _mm_movpi64_epi64(), not _mm_movpi64_pi64().
> Hi Alexey,
>
> This belongs on the cfe-commits list, and I have already posted the same fix there:
>
> http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20131104/092514.html

Alexey, nice investigation. I've confirmed correctness and landed 
Dimitry's patch in r195558.

Alp.


>
> -Dimitry
>
>
>
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