Search all intrinsics
SIMD ISAReturn TypeNameArgumentsInstruction Group
Neonfloat32x2_tvbfdot_f32(float32x2_t r, bfloat16x4_t a, bfloat16x4_t b)Vector arithmetic / Dot product
Description
BFloat16 floating-point dot product (vector). This instruction delimits the source vectors into pairs of 16-bit BF16 elements. Within each pair, the elements in the first source vector are multiplied by the corresponding 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. The instruction ignores the FPCR and does not update the FPSR exception status.
Results
Vd.2S result
This intrinsic compiles to the following instructions:

BFDOT Vd.2S,Vn.4H,Vm.4H

Argument Preparation
r register: Vd.2Sa register: Vn.4Hb register: Vm.4H
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;