FDOT (2-way, indexed, FP8 to FP16)

8-bit floating-point indexed dot product to half-precision

This instruction computes the fused sum-of-products of a group of two 8-bit floating-point values held in each 16-bit element of the first source vector and a group of two 8-bit floating-point values in an indexed 16-bit element of the second source vector. The half-precision sum-of-products are scaled by 2^{-UInt(FPMR.LSCALE[3:0])}, before being destructively added without intermediate rounding to the corresponding half-precision elements of the destination vector.

The 8-bit floating-point groups within the second source vector are specified using an immediate index which selects the same group position within each 128-bit vector segment. The 8-bit floating-point encoding format for the elements of the first source vector and the second source vector is selected by FPMR.F8S1 and FPMR.F8S2 respectively.

This instruction is unpredicated.

SVE2
(FEAT_FP8DOT2)

if !HaveSVE2FP8DOT2() then UNDEFINED; integer n = UInt(Zn); integer m = UInt(Zm); integer da = UInt(Zda); integer index = UInt(i3h:i3l);