[X86][AVX10.2] Add comments for the avx10_2copyintrin.h file (#119238)

As in title

Author: mikolaj-pirog

clang/lib/Headers/avx10_2copyintrin.h

@@ -19,11 +19,43 @@
   __attribute__((__always_inline__, __nodebug__, __target__("avx10.2-256"),    \
                  __min_vector_width__(128)))
 
+/// Constructs a 128-bit integer vector, setting the lower 32 bits to the
+///    lower 32 bits of the parameter \a __A; the upper bits are zeoroed.
+///
+/// \code{.operation}
+/// result[31:0] := __A[31:0]
+/// result[MAX:32] := 0
+/// \endcode
+///
+/// \headerfile <immintrin.h>
+///
+/// This intrinsic corresponds to the <c> VMOVD </c> instruction.
+///
+/// \param __A
+///    A 128-bit integer vector.
+/// \returns A 128-bit integer vector. The lower 32 bits are copied from the
+///    parameter \a __A; the upper bits are zeroed.
 static __inline__ __m128i __DEFAULT_FN_ATTRS128 _mm_move_epi32(__m128i __A) {
   return (__m128i)__builtin_shufflevector(
       (__v4si)__A, (__v4si)_mm_setzero_si128(), 0, 4, 4, 4);
 }
 
+/// Constructs a 128-bit integer vector, setting the lower 16 bits to the
+///    lower 16 bits of the parameter \a __A; the upper bits are zeoroed.
+///
+/// \code{.operation}
+/// result[15:0] := __A[15:0]
+/// result[MAX:16] := 0
+/// \endcode
+///
+/// \headerfile <immintrin.h>
+///
+/// This intrinsic corresponds to the <c> VMOVW </c> instruction.
+///
+/// \param __A
+///    A 128-bit integer vector.
+/// \returns A 128-bit integer vector. The lower 16 bits are copied from the
+///    parameter \a __A; the upper bits are zeroed.
 static __inline__ __m128i __DEFAULT_FN_ATTRS128 _mm_move_epi16(__m128i __A) {
   return (__m128i)__builtin_shufflevector(
       (__v8hi)__A, (__v8hi)_mm_setzero_si128(), 0, 8, 8, 8, 8, 8, 8, 8);