================
@@ -614,12 +623,15 @@ _mm_shuffle_epi8(__m128i __a, __m128i __b)
/// 1: Clear the corresponding byte in the destination. \n
/// 0: Copy the selected source byte to the corresponding byte in the
/// destination. \n
-/// Bits [3:0] select the source byte to be copied.
+/// Bits [2:0] select the source byte to be copied.
/// \returns A 64-bit integer vector containing the copied or cleared values.
-static __inline__ __m64 __DEFAULT_FN_ATTRS_MMX
+static __inline__ __m64 __DEFAULT_FN_ATTRS
_mm_shuffle_pi8(__m64 __a, __m64 __b)
{
- return (__m64)__builtin_ia32_pshufb((__v8qi)__a, (__v8qi)__b);
+ return __trunc64(__builtin_ia32_pshufb128(
+ (__v16qi)__builtin_shufflevector(
+ (__v2si)(__a), __extension__ (__v2si){}, 0, 1, 0, 1),
----------------
jyknight wrote:
The behavior is supposed to be that only the bottom 3 bits of `__b` affect the
result for the 64-bit operation. For the 128-bit operation, however, the bottom
4 bits are used.
By duplicating the input vector, we automatically get the proper behavior
without having to mask out bit 3 of `__b`.
https://github.com/llvm/llvm-project/pull/96540
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