vrs8_expf: Eight-valued single precision exponential function

• Prototype:
  • __m128,__m128 __vrs8_expf(__m128 x1, __m128 x2);
    Note that this function uses a non-standard programming interface. The two __m128 inputs, which contain eight single precision values, are passed by the AMD64 C ABI in registers xmm0, and xmm1. The corresponding results are returned in xmm0 and xmm1. The use of xmm1 to return a __m128 is non-standard, and this function can not be called directly from C. It can be called directly from assembly language. It is intended for internal use by vectorizing compilers, that may be able to take advantage of the non-standard calling interface.
  • Inputs:
    • __m128 x1 - the first single precision vector of four input values.
      __m128 x2 - the second single precision vector of four input values.
  • Outputs:
    • __m128 y1 - the first four single precision exponent results, returned in xmm0.
      __m128 y2 - the second four single precision exponent results, returned in xmm1.
• Notes:
  • __vrs8_expf computes the single precision exponential function of eight input arguments.
    
    This routine accepts eight single precision input values passed as two __m128 values. The result is the single precision exponent of the eight values, returned as two __m128 values. This is a relaxed version of exp, suitable for use with fastmath compiler flags or applications not requiring full error handling. Denormal inputs may produce unpredictable results. Special case inputs produce C99 return values. The routine is accurate to better than 1 ulp over the valid input range.
• Special case return values:

  • Input	Output
    QNaN	same QNaN
    SNaN	same NaN converted to QNaN
    < -87.5	0
    > 88	+infinity

• Performance:
  • 155 cycles for most valid inputs (19 cycles per value).