UDOT (2-way, vectors)

Unsigned integer dot product (two-way)

This instruction calculates the dot product of a pair of unsigned 8-bit or 16-bit integer values held in each 16-bit or 32-bit element of the first source vector multiplied by a pair of unsigned 8-bit or 16-bit integer values in the corresponding 16-bit or 32-bit element of the second source vector, and then destructively adds the widened dot product to the corresponding 16-bit or 32-bit element of the destination vector.

This instruction is unpredicated.

It has encodings from 2 classes: 8-bit to 16-bit and 16-bit to 32-bit

8-bit to 16-bit
(FEAT_SVE2p3 || FEAT_SME2p3)

313029282726252423222120191817161514131211109876543210
01000100010Zm000001ZnZda
sizeU

Encoding

UDOT <Zda>.H, <Zn>.B, <Zm>.B

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p3) && !IsFeatureImplemented(FEAT_SME2p3) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 16; let n : integer = UInt(Zn); let m : integer = UInt(Zm); let da : integer = UInt(Zda);

16-bit to 32-bit
(FEAT_SME2 || FEAT_SVE2p1)

313029282726252423222120191817161514131211109876543210
01000100000Zm110011ZnZda
U

Encoding

UDOT <Zda>.S, <Zn>.H, <Zm>.H

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME2) && !IsFeatureImplemented(FEAT_SVE2p1) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 32; let n : integer = UInt(Zn); let m : integer = UInt(Zm); let da : integer = 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.

Operational information

This instruction is a data-independent-time instruction as described in About PSTATE.DIT.

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


2025-12_rel 2025-12-10 16:41:45

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