Multi-vector BFloat16 multiply-add by vector to single-precision
This instruction widens all 16-bit BFloat16 elements in the one, two, or four first source vectors and the second source vector to single-precision format, then multiplies the corresponding elements and destructively adds these values without intermediate rounding to the overlapping 32-bit single-precision elements of the ZA double-vector groups.
The double-vector group within all of, each half of, or each quarter of the ZA array is selected by the sum of the vector select register and offset range, modulo all, half, or quarter the number of ZA array vectors.
The vector group symbol, VGx2 or VGx4, indicates that the ZA operand consists of two or four ZA double-vector groups respectively. The vector group symbol is preferred for disassembly, but optional in assembler source code.
This instruction follows SME ZA-targeting floating-point behaviors.
This instruction is unpredicated.
It has encodings from 3 classes: One ZA double-vector , Two ZA double-vectors and Four ZA double-vectors
| 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 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | Zm | 0 | Rv | 0 | 1 | 1 | Zn | 1 | 0 | off3 | ||||||||||
| op | S | ||||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF); end; let v : integer = UInt('010'::Rv); let n : integer = UInt(Zn); let m : integer = UInt('0'::Zm); let offset : integer = UInt(off3::'0'); let nreg : integer{} = 1;
| 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 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | Zm | 0 | Rv | 0 | 1 | 0 | Zn | 1 | 0 | 0 | off2 | |||||||||
| op | S | o2 | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF); end; let v : integer = UInt('010'::Rv); let n : integer = UInt(Zn); let m : integer = UInt('0'::Zm); let offset : integer = UInt(off2::'0'); let nreg : integer{} = 2;
| 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 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 1 | Zm | 0 | Rv | 0 | 1 | 0 | Zn | 1 | 0 | 0 | off2 | |||||||||
| op | S | o2 | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF); end; let v : integer = UInt('010'::Rv); let n : integer = UInt(Zn); let m : integer = UInt('0'::Zm); let offset : integer = UInt(off2::'0'); let nreg : integer{} = 4;
| <Wv> |
Is the 32-bit name of the vector select register W8-W11, encoded in the "Rv" field. |
| <Zn> |
Is the name of the first source scalable vector register, encoded in the "Zn" field. |
| <Zm> |
Is the name of the second source scalable vector register Z0-Z15, encoded in the "Zm" field. |
| <Zn1> |
Is the name of the first scalable vector register of the first source multi-vector group, encoded as "Zn". |
| <Zn2> |
Is the name of the second scalable vector register of the first source multi-vector group, encoded as "Zn" plus 1 modulo 32. |
| <Zn4> |
Is the name of the fourth scalable vector register of the first source multi-vector group, encoded as "Zn" plus 3 modulo 32. |
CheckStreamingSVEAndZAEnabled(); let VL : integer{} = CurrentVL(); let elements : integer = VL DIV 32; let vectors : integer = VL DIV 8; let vstride : integer = vectors DIV nreg; let vbase : bits(32) = X{}(v); var vec : integer = (UInt(vbase) + offset) MOD vstride; var result : bits(VL); vec = vec - (vec MOD 2); for r = 0 to nreg-1 do let op1 : bits(VL) = Z{}((n+r) MOD 32); let op2 : bits(VL) = Z{}(m); for i = 0 to 1 do let op3 : bits(VL) = ZAvector{}(vec + i); for e = 0 to elements-1 do let elem1 : bits(16) = op1[(2 * e + i)*:16]; let elem2 : bits(16) = op2[(2 * e + i)*:16]; let elem3 : bits(32) = op3[e*:32]; result[e*:32] = BFMulAddH_ZA(elem3, elem1, elem2, FPCR()); end; ZAvector{VL}(vec + i) = result; end; vec = vec + vstride; end;
2026-03_rel 2026-03-26 20:48:11
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