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USMMLA

Unsigned by signed integer matrix multiply-accumulate.

The unsigned by signed integer matrix multiply-accumulate instruction multiplies the 2×8 matrix of unsigned 8-bit integer values held in each 128-bit segment of the first source vector by the 8×2 matrix of signed 8-bit integer values in the corresponding segment of the second source vector. The resulting 2×2 widened 32-bit integer matrix product is then destructively added to the 32-bit integer matrix accumulator held in the corresponding segment of the addend and destination vector. This is equivalent to performing an 8-way dot product per destination element.

This instruction is unpredicated.

ID_AA64ZFR0_EL1.I8MM indicates whether this instruction is implemented.

313029282726252423222120191817161514131211109876543210
01000101100Zm100110ZnZda

SVE

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

if !HaveSVE() || !HaveInt8MatMulExt() then UNDEFINED;
integer n = UInt(Zn);
integer m = UInt(Zm);
integer da = UInt(Zda);
boolean op1_unsigned = TRUE;
boolean op2_unsigned = FALSE;

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 segments = VL DIV 128;
bits(VL) operand1 = Z[n];
bits(VL) operand2 = Z[m];
bits(VL) operand3 = Z[da];
bits(VL) result = Zeros();
bits(128) op1, op2;
bits(128) res, addend;

for s = 0 to segments-1
    op1    = Elem[operand1, s, 128];
    op2    = Elem[operand2, s, 128];
    addend = Elem[operand3, s, 128];
    res    = MatMulAdd(addend, op1, op2, op1_unsigned, op2_unsigned);
    Elem[result, s, 128] = res;

Z[da] = result;

Operational information

This instruction might be immediately preceded in program order by a MOVPRFX instruction that conforms to all of the following requirements, otherwise the behavior of either or both instructions is unpredictable:

  • 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.
The MOVPRFX instructions that can be used with this instruction are as follows:
  • An unpredicated MOVPRFX instruction.