Function _mm_reduce_ss 

pub fn _mm_reduce_ss(a: __m128, b: __m128, const IMM8: i32) -> __m128

Available on x86 and target feature avx512dq only.

Extract the reduced argument of the lower single-precision (32-bit) floating-point element in b by the number of bits specified by imm8, store the result in the lower element of dst, and copy the upper element from a. to the upper element of dst. Rounding is done according to the imm8 parameter, which can be one of:

• _MM_FROUND_TO_NEAREST_INT : round to nearest
• _MM_FROUND_TO_NEG_INF : round down
• _MM_FROUND_TO_POS_INF : round up
• _MM_FROUND_TO_ZERO : truncate
• _MM_FROUND_CUR_DIRECTION : use MXCSR.RC - see _MM_SET_ROUNDING_MODE

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