USDOT (vectors)
Unsigned by signed integer dot product
The unsigned by signed integer dot product instruction computes the dot product of a group of four unsigned 8-bit integer values held in each 32-bit element of the first source vector multiplied by a group of four signed 8-bit integer values in the corresponding 32-bit element of the second source vector, and then destructively adds the widened dot product to the corresponding 32-bit element of the destination vector.
This instruction is unpredicated.
ID_AA64ZFR0_EL1.I8MM indicates whether this instruction is implemented.
Green
False
True
True
0
1
0
0
0
1
0
0
1
0
0
0
1
1
1
1
0
USDOT <Zda>.S, <Zn>.B, <Zm>.B
if ((!IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME)) ||
!IsFeatureImplemented(FEAT_I8MM)) then UNDEFINED;
constant integer esize = 32;
constant integer n = UInt(Zn);
constant integer m = UInt(Zm);
constant integer da = UInt(Zda);
<Zda>
Is the name of the third source and destination scalable vector register, encoded in the "Zda" field.
<Zn>
Is the name of the first source scalable vector register, encoded in the "Zn" field.
<Zm>
Is the name of the second source scalable vector register, encoded in the "Zm" field.
CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
constant bits(VL) operand1 = Z[n, VL];
constant bits(VL) operand2 = Z[m, VL];
constant bits(VL) operand3 = Z[da, VL];
bits(VL) result;
for e = 0 to elements-1
bits(esize) res = Elem[operand3, e, esize];
for i = 0 to 3
constant integer element1 = UInt(Elem[operand1, 4 * e + i, esize DIV 4]);
constant integer element2 = SInt(Elem[operand2, 4 * e + i, esize DIV 4]);
res = res + element1 * element2;
Elem[result, e, esize] = res;
Z[da, VL] = result;