FTMOPA (widening, 2-way, FP16 to FP32)

Half-precision sparse sum of two outer products, accumulating

This instruction generates half-precision sum of outer products by multiplying the 2-in-4 selected elements from the dense sub-matrices in the two first source vectors with the corresponding elements of the compressed sparse sub-matrix in the second source vector and accumulates the results to the corresponding elements of a 32-bit element ZA tile.

The sum of outer products is generated by multiplying the selected 2-in-4 half-precision values from each overlapping 32-bit containers of the two SVL_S×2 sub-matrices in the first source vectors by the two half-precision values from the corresponding 32-bit container of the 2×SVL_S sub-matrix in the second source vector. The two selected elements from each overlapping 32-bit containers of the first source vectors correspond to 2-in-4 elements of rows of two SVL_S×2 sub-matrices. Each 32-bit container of the second source vector holds 2 elements of columns of a compressed 2×SVL_S sub-matrix.

The 2-in-4 half-precision values from overlapping 32-bit containers of the first source vectors are selected by 4-bit controls in the indexed segment of the control vector register. If the control bit corresponding to an element in the first source vectors is 0, the element is discarded and does not contribute to the sum of products result. If more than two bits of the 4-bit control corresponding to 32-bit containers of the first source vectors are 1, only the elements corresponding to the least two significant bits are selected.

The instruction widens the selected elements of sub-matrices of half-precision values held in the first source vectors to single-precision values and multiplies them by the corresponding widened elements of sub-matrix of half-precision values in the second source vector to single-precision values. The resulting SVL_S×SVL_S single-precision sum of outer products is then destructively added to the single-precision destination tile. This is equivalent to performing a 2-way dot product and accumulate to each of the destination tile elements.

This instruction follows SME ZA-targeting floating-point behaviors.

This instruction is unpredicated.

SME2
(FEAT_SME_TMOP)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME_TMOP) then EndOfDecode(Decode_UNDEF); constant integer n = UInt(Zn:'0'); constant integer m = UInt(Zm); constant integer k = UInt('1':K:'1':Zk); constant integer index = UInt(i2); constant integer da = UInt(ZAda);