VFMAB, VFMAT (BFloat16, vector)
BFloat16 floating-point widening multiply-add long (vector)
The Bfloat16 floating-point widening multiply-add long instruction widens the even-numbered (bottom)
or odd-numbered (top) 16-bit elements in the first and second source vectors from Bfloat16 to single-precision format. The instruction then multiplies
and adds these values to the overlapping single-precision elements of the destination vector.
Unlike other BFloat16 multiplication instructions, this performs a fused multiply-add, without intermediate
rounding that uses the Round to Nearest rounding mode and can generate a floating-point exception that causes
cumulative exception bits in the FPSCR to be set.
It has encodings from the following instruction sets:
A32 (
A1
)
and
T32 (
T1
)
.
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VFMA<bt>{<q>}.BF16 <Qd>, <Qn>, <Qm>
if !IsFeatureImplemented(FEAT_AA32BF16) then Undefined(); end;
if Vd[0] == '1' || Vn[0] == '1' || Vm[0] == '1' then Undefined(); end;
let d : integer = UInt(D::Vd);
let n : integer = UInt(N::Vn);
let m : integer = UInt(M::Vm);
let elements : integer = 128 DIV 32;
let sel : integer = UInt(Q);
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VFMA<bt>{<q>}.BF16 <Qd>, <Qn>, <Qm>
if InITBlock() then UnpredictableProcedure(); end;
if !IsFeatureImplemented(FEAT_AA32BF16) then Undefined(); end;
if Vd[0] == '1' || Vn[0] == '1' || Vm[0] == '1' then Undefined(); end;
let d : integer = UInt(D::Vd);
let n : integer = UInt(N::Vn);
let m : integer = UInt(M::Vm);
let elements : integer = 128 DIV 32;
let sel : integer = UInt(Q);
<bt>
Is the bottom or top element specifier,
<q>
See Standard assembler syntax fields.
<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();
let fpcr : FPCR_Type = StandardFPCR();
let operand1 : bits(128) = Q(n>>1);
let operand2 : bits(128) = Q(m>>1);
let operand3 : bits(128) = Q(d>>1);
var result : bits(128);
for e = 0 to elements-1 do
let element1 : bits(32) = operand1[(2 * e + sel)*:16] :: Zeros{16};
let element2 : bits(32) = operand2[(2 * e + sel)*:16] :: Zeros{16};
let addend : bits(32) = operand3[e*:32];
result[e*:32] = FPMulAdd{32}(addend, element1, element2, fpcr);
end;
Q(d>>1) = result;
2026-03-26 20:27:25
2026-03_rel