BFloat16 floating-point matrix multiply-accumulate. This instruction multiplies the 2x4 matrix of BF16 values in the first 128-bit source vector by the 4x2 BF16 matrix in the second 128-bit source vector. The resulting 2x2 single-precision matrix product is then added destructively to the 2x2 single-precision matrix in the 128-bit destination vector. This is equivalent to performing a 4-way dot product per destination element. The instruction does not update the FPSCR exception status.
Arm expects that the VMMLA instruction will deliver a peak BF16 multiply throughput that is at least as high as can be achieved using two VDOT instructions, with a goal that it should have significantly higher throughput.
It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | D | 0 | 0 | Vn | Vd | 1 | 1 | 0 | 0 | N | 1 | M | 0 | Vm | |||||||||
if !IsFeatureImplemented(FEAT_AA32BF16) then UNDEFINED; if Vd<0> == '1' || Vn<0> == '1' || Vm<0> == '1' then UNDEFINED; constant integer d = UInt(D:Vd); constant integer n = UInt(N:Vn); constant integer m = UInt(M:Vm); constant integer regs = 2;
| 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | D | 0 | 0 | Vn | Vd | 1 | 1 | 0 | 0 | N | 1 | M | 0 | Vm | |||||||||
if InITBlock() then UNPREDICTABLE; if !IsFeatureImplemented(FEAT_AA32BF16) then UNDEFINED; if Vd<0> == '1' || Vn<0> == '1' || Vm<0> == '1' then UNDEFINED; constant integer d = UInt(D:Vd); constant integer n = UInt(N:Vn); constant integer m = UInt(M:Vm); constant integer regs = 2;
| <q> |
| <Qd> |
Is the 128-bit name of the SIMD&FP destination register, encoded in the "D:Vd" field as <Qd>*2. |
| <Qn> |
Is the 128-bit name of the first SIMD&FP source register, encoded in the "N:Vn" field as <Qn>*2. |
| <Qm> |
Is the 128-bit name of the second SIMD&FP source register, encoded in the "M:Vm" field as <Qm>*2. |
CheckAdvSIMDEnabled(); constant bits(128) op1 = Q[n>>1]; constant bits(128) op2 = Q[m>>1]; constant bits(128) acc = Q[d>>1]; constant FPCR_Type fpcr = EffectiveFPCR(); Q[d>>1] = BFMatMulAdd(acc, op1, op2, fpcr);
Internal version only: isa v01_32, pseudocode v2024-12_rel ; Build timestamp: 2024-12-16T10:54
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