SSE2 intrinsics: gcc46 vs. clang contradiction

[Alp Toker]

Thanks Dimitry, I've confirmed your fix is correct.

Landed in r195558.

Alp.


On 02/11/2013 00:07, Dimitry Andric wrote:
> On 01 Nov 2013, at 22:45, C. Bergström <cbergstrom at pathscale.com> wrote:
>> On 11/ 1/13 10:43 PM, Alexey Dokuchaev wrote:
>>> On Fri, Nov 01, 2013 at 07:46:45PM +0700, Alexey Dokuchaev wrote:
>>>> What adds to confusion, in their manual [1] Intel spells them differently
>>>> themselves: first, in the table, it says:
>>>>
>>>>    _mm_movpi64_epi64		Move		MOVDQ2Q
>>>>                ^^^^^
>>>>
>>>> Then later, when they describe what it does, it says:
>>>>
>>>>    __m128i _mm_movpi64_pi64(__m64 a)
>>>>                        ^^^^
>>>>    Moves the 64 bits of a to the lower 64 bits of the result, zeroing the
>>>>    upper bits.
>>> 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:
>>>
>>>    _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)
>>>    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().
>> Why isn't this being asked on the clang or llvm mailing list? Wouldn't this impact upstream as well?
> Indeed, so redirecting to the cfe-commits list.  It looks like this incorrect function name has been in emmintrin.h since clang r61443 (by andersca).  Basically, we need the typo fixed as follows:
>
> Index: tools/clang/lib/Headers/emmintrin.h
> ===================================================================
> --- tools/clang/lib/Headers/emmintrin.h (revision 193039)
> +++ tools/clang/lib/Headers/emmintrin.h (working copy)
> @@ -1366,7 +1366,7 @@ _mm_movepi64_pi64(__m128i __a)
>   }
>
>   static __inline__ __m128i __attribute__((__always_inline__, __nodebug__))
> -_mm_movpi64_pi64(__m64 __a)
> +_mm_movpi64_epi64(__m64 __a)
>   {
>     return (__m128i){ (long long)__a, 0 };
>   }
>
> Is this OK?
>
> -Dimitry
>
>
>
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