Arm® A64 Instruction Set Architecture: Future Architecture Technologies in the A architecture profile

USMMLA (vector)

Unsigned and signed 8-bit integer matrix multiply-accumulate. This instruction multiplies the 2x8 matrix of unsigned 8-bit integer values in the first source vector by the 8x2 matrix of signed 8-bit integer values in the second source vector. The resulting 2x2 32-bit integer matrix product is destructively added to the 32-bit integer matrix accumulator in the destination vector. This is equivalent to performing an 8-way dot product per destination element.

From Armv8.2, this is an optional instruction. ID_AA64ISAR0_EL1.I8MM indicates whether this instruction is supported.

Vector
(Armv8.6)

if !HaveInt8MatMulExt() then UNDEFINED;
integer n = UInt(Rn);
integer m = UInt(Rm);
integer d = UInt(Rd);

Assembler Symbols

CheckFPAdvSIMDEnabled64();
bits(128) operand1 = V[n];
bits(128) operand2 = V[m];
bits(128) addend = V[d];

V[d] = MatMulAdd(addend, operand1, operand2, TRUE, FALSE);