UDOT (by element)

Dot Product unsigned arithmetic (vector, by element). This instruction performs the dot product of the four 8-bit elements in each 32-bit element of the first source register with the four 8-bit elements of an indexed 32-bit element in the second source register, accumulating the result into the corresponding 32-bit element of the destination register.

Depending on the settings in the CPACR_EL1, CPTR_EL2, and CPTR_EL3 registers, and the current Security state and Exception level, an attempt to execute the instruction might be trapped.

In Armv8.2 and Armv8.3, this is an optional instruction. From Armv8.4 it is mandatory for all implementations to support it.

ID_AA64ISAR0_EL1.DP indicates whether this instruction is supported.

Vector
(FEAT_DotProd)

if !HaveDOTPExt() then UNDEFINED; if size != '10' then UNDEFINED; boolean signed = (U=='0'); integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(M:Rm); integer index = UInt(H:L); integer esize = 8 << UInt(size); integer datasize = if Q == '1' then 128 else 64; integer elements = datasize DIV esize;