USDOT (by element)

Dot Product index form with unsigned and signed integers. This instruction performs the dot product of the four unsigned 8-bit integer values in each 32-bit element of the first source register with the four signed 8-bit integer values in an indexed 32-bit element of the second source register, accumulating the result into the corresponding 32-bit element of the destination register.

From Armv8.2 to Armv8.5, this is an OPTIONAL instruction. From Armv8.6 it is mandatory for implementations that include Advanced SIMD to support it. ID_AA64ISAR1_EL1.I8MM indicates whether this instruction is supported.

Vector
(FEAT_I8MM)

if !IsFeatureImplemented(FEAT_I8MM) then UNDEFINED; boolean op1_unsigned = (US == '1'); boolean op2_unsigned = (US == '0'); integer n = UInt(Rn); integer m = UInt(M:Rm); integer d = UInt(Rd); integer i = UInt(H:L); constant integer datasize = 64 << UInt(Q); integer elements = datasize DIV 32;