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SIMD ISAReturn TypeNameArgumentsInstruction Group
Neonfloat32x2_tvbfdot_laneq_f32(float32x2_t r, bfloat16x4_t a, bfloat16x8_t b, const int lane)Vector arithmetic / Dot product
Description
BFloat16 floating-point dot product (vector, by element). This instruction delimits the source vectors into pairs of 16-bit BF16 elements. Each pair of elements in the first source vector is multiplied by the specified pair of elements in the second source vector. The resulting single-precision products are then summed and added destructively to the single-precision element of the destination vector that aligns with the pair of BF16 values in the first source vector.
Results
Vd.2S result
This intrinsic compiles to the following instructions:

BFDOT Vd.2S,Vn.4H,Vm.2H[lane]

Argument Preparation
r register: Vd.2Sa register: Vn.4Hb register: Vm.8Hlane minimum: 0; maximum: 3
Architectures
A32, A64

Operation

CheckFPAdvSIMDEnabled64();
bits(datasize) operand1 = V[n];
bits(datasize) operand2 = V[m];
bits(datasize) operand3 = V[d];
bits(datasize) result;

for e = 0 to elements-1
    bits(16) elt1_a = Elem[operand1, 2 * e + 0, 16];
    bits(16) elt1_b = Elem[operand1, 2 * e + 1, 16];
    bits(16) elt2_a = Elem[operand2, 2 * e + 0, 16];
    bits(16) elt2_b = Elem[operand2, 2 * e + 1, 16];

    bits(32) sum = Elem[operand3, e, 32];
    sum = BFDotAdd(sum, elt1_a, elt1_b, elt2_a, elt2_b, FPCR[]);
    Elem[result, e, 32] = sum;

V[d] = result;