UDOT (indexed)

The unsigned integer indexed dot product instruction computes the dot product of a group of four unsigned 8-bit or 16-bit integer values held in each 32-bit or 64-bit element of the first source vector multiplied by a group of four unsigned 8-bit or 16-bit integer values in an indexed 32-bit or 64-bit element of the second source vector, and then destructively adds the widened dot product to the corresponding 32-bit or 64-bit element of the destination vector.

The groups within the second source vector are specified using an immediate index which selects the same group position within each 128-bit vector segment. The index range is from 0 to one less than the number of groups per 128-bit segment, encoded in 1 to 2 bits depending on the size of the group. This instruction is unpredicated.

32-bit

if !HaveSVE() && !HaveSME() then UNDEFINED; integer esize = 32; integer index = UInt(i2); integer n = UInt(Zn); integer m = UInt(Zm); integer da = UInt(Zda);

64-bit

if !HaveSVE() && !HaveSME() then UNDEFINED; integer esize = 64; integer index = UInt(i1); integer n = UInt(Zn); integer m = UInt(Zm); integer da = UInt(Zda);

Assembler Symbols

<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>	For the 32-bit variant: is the name of the second source scalable vector register Z0-Z7, encoded in the "Zm" field.
	For the 64-bit variant: is the name of the second source scalable vector register Z0-Z15, encoded in the "Zm" field.

<imm>	For the 32-bit variant: is the immediate index of a quadtuplet of four 8-bit elements within each 128-bit vector segment, in the range 0 to 3, encoded in the "i2" field.
	For the 64-bit variant: is the immediate index of a quadtuplet of four 16-bit elements within each 128-bit vector segment, in the range 0 to 1, encoded in the "i1" field.

Operation

CheckSVEEnabled(); integer elements = VL DIV esize; integer eltspersegment = 128 DIV esize; bits(VL) operand1 = Z[n]; bits(VL) operand2 = Z[m]; bits(VL) operand3 = Z[da]; bits(VL) result; for e = 0 to elements-1 integer segmentbase = e - (e MOD eltspersegment); integer s = segmentbase + index; bits(esize) res = Elem[operand3, e, esize]; for i = 0 to 3 integer element1 = UInt(Elem[operand1, 4 * e + i, esize DIV 4]); integer element2 = UInt(Elem[operand2, 4 * s + i, esize DIV 4]); res = res + element1 * element2; Elem[result, e, esize] = res; Z[da] = result;

Operational information

This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX instruction must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is unpredictable:

The MOVPRFX instruction must be unpredicated.
The MOVPRFX instruction must specify the same destination register as this instruction.
The destination register must not refer to architectural register state referenced by any other source operand register of this instruction.

Internal version only: isa v33.11seprel, AdvSIMD v29.05, pseudocode v2021-09_rel, sve v2021-09_rc3d ; Build timestamp: 2021-10-06T11:41

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	0	0	0	1	0	0	1	0	1	i2		Zm			0	0	0	0	0	1	Zn					Zda
								size<1>	size<0>												U

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	0	0	0	1	0	0	1	1	1	i1	Zm				0	0	0	0	0	1	Zn					Zda
								size<1>	size<0>												U