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.

SVE
(FEAT_I8MM)

313029282726252423222120191817161514131211109876543210
01000100100Zm011110ZnZda
size<1>size<0>

USDOT <Zda>.S, <Zn>.B, <Zm>.B

if (!HaveSVE() && !HaveSME()) || !HaveInt8MatMulExt() then UNDEFINED; integer esize = 32; 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>

Is the name of the second source scalable vector register, encoded in the "Zm" field.

Operation

CheckSVEEnabled(); integer elements = VL 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 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 = SInt(Elem[operand2, 4 * e + 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:


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

Copyright © 2010-2021 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.