Arm® A32/T32 Instruction Set Architecture: Armv8, for Armv8-A architecture profile Documentation

VUDOT (vector)

Dot Product vector form with unsigned integers. 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 the corresponding 32-bit element in the second source register, accumulating the result into the corresponding 32-bit element of the destination register.

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

ID_ISAR6.DP indicates whether this instruction is supported.

It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .

A1
(Armv8.2)

if !HaveDOTPExt() then UNDEFINED;
if Q == '1' && (Vd<0> == '1' || Vn<0> == '1' || Vm<0> == '1') then UNDEFINED;
boolean signed = U=='0';
integer d = UInt(D:Vd);
integer n = UInt(N:Vn);
integer m = UInt(M:Vm);
integer esize = 32;
integer regs = if Q == '1' then 2 else 1;

T1
(Armv8.2)

if InITBlock() then UNPREDICTABLE;
if !HaveDOTPExt() then UNDEFINED;
if Q == '1' && (Vd<0> == '1' || Vn<0> == '1' || Vm<0> == '1') then UNDEFINED;
boolean signed = U=='0';
integer d = UInt(D:Vd);
integer n = UInt(N:Vn);
integer m = UInt(M:Vm);
integer esize = 32;
integer regs = if Q == '1' then 2 else 1;

Assembler Symbols

bits(64) operand1;
bits(64) operand2;
bits(64) result;
CheckAdvSIMDEnabled();
for r = 0 to regs-1
    operand1 = D[n+r];
    operand2 = D[m+r];
    result = D[d+r];
    integer element1, element2;
    for e = 0 to 1
        integer res = 0;
        for i = 0 to 3
            if signed then
                element1 = SInt(Elem[operand1, 4 * e + i, esize DIV 4]);
                element2 = SInt(Elem[operand2, 4 * e + i, esize DIV 4]);
            else
                element1 = UInt(Elem[operand1, 4 * e + i, esize DIV 4]);
                element2 = UInt(Elem[operand2, 4 * e + i, esize DIV 4]);
            res = res + element1 * element2;
        Elem[result, e, esize] = Elem[result, e, esize] + res;
    D[d+r] = result;