Multi-vector 8-bit floating-point vertical dot product by indexed element to half-precision
This instruction calculates the fused sum-of-products of each vertical pair of 8-bit floating-point values held in the corresponding elements of the two first source vectors with horizontal pair of 8-bit floating-point values in the indexed 16-bit group of the corresponding 128-bit segment of the second source vector. The half-precision sum-of-products are scaled by 2-UInt(FPMR.LSCALE[3:0]), before being destructively added without intermediate rounding to the corresponding half-precision elements of the two ZA single-vector groups. The 8-bit floating-point encoding format for the elements of the first source vector and the second source vector is selected by FPMR.F8S1 and FPMR.F8S2 respectively.
The 8-bit floating-point pairs within the second source vector are specified using an immediate index that selects the same pair position within each 128-bit vector segment.
The single-vector group within each half of the ZA array is selected by the sum of the vector select register and offset, modulo half the number of ZA array vectors.
The vector group symbol VGx2 indicates that the ZA operand consists of two ZA single-vector groups. The vector group symbol is preferred for disassembly, but optional in assembler source code.
This instruction is unpredicated.
| 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 | 1 | 1 | 0 | 1 | Zm | 0 | Rv | 1 | i3h | Zn | 1 | 0 | i3l | off3 | ||||||||||
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if !IsFeatureImplemented(FEAT_SME_F8F16) then EndOfDecode(Decode_UNDEF); end; let v : integer = UInt('010'::Rv); let n : integer = UInt(Zn::'0'); let m : integer = UInt('0'::Zm); let offset : integer = UInt(off3); let index : integer = UInt(i3h::i3l);
| <Wv> |
Is the 32-bit name of the vector select register W8-W11, encoded in the "Rv" field. |
| <offs> |
Is the vector select offset, in the range 0 to 7, encoded in the "off3" field. |
| <Zn1> |
Is the name of the first scalable vector register of the first source multi-vector group, encoded as "Zn" times 2. |
| <Zn2> |
Is the name of the second scalable vector register of the first source multi-vector group, encoded as "Zn" times 2 plus 1. |
| <Zm> |
Is the name of the second source scalable vector register Z0-Z15, encoded in the "Zm" field. |
| <index> |
Is the immediate index of a pair of 8-bit elements within each 128-bit vector segment, in the range 0 to 7, encoded in the "i3h:i3l" fields. |
CheckFPMREnabled(); CheckStreamingSVEAndZAEnabled(); let VL : integer{} = CurrentVL(); let elements : integer = VL DIV 16; let vectors : integer = VL DIV 8; let vstride : integer = vectors DIV 2; let eltspersegment : integer = 128 DIV 16; let vbase : bits(32) = X{}(v); var vec : integer = (UInt(vbase) + offset) MOD vstride; var result : bits(VL); for r = 0 to 1 do let operand1a : bits(VL) = Z{}(n+0); let operand1b : bits(VL) = Z{}(n+1); let operand2 : bits(VL) = Z{}(m); let operand3 : bits(VL) = ZAvector{}(vec); for e = 0 to elements-1 do var op1 : bits(16); op1[0+:8] = operand1a[(2 * e + r)*:8]; op1[1*:8] = operand1b[(2 * e + r)*:8]; let segmentbase : integer = e - (e MOD eltspersegment); let s : integer = segmentbase + index; let op2 : bits(16) = operand2[s*:16]; var sum : bits(16) = operand3[e*:(16)]; sum = FP8DotAddFP{16, 16}(sum, op1, op2, FPCR(), FPMR()); result[e*:(16)] = sum; end; ZAvector{VL}(vec) = result; vec = vec + vstride; end;
2026-03_rel 2026-03-26 20:48:11
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