Multi-vector floating-point multiply-subtract long

This half-precision floating-point multiply-subtract long instruction widens all 16-bit half-precision elements in the two or four first and second source vectors to single-precision format, then multiplies the corresponding elements and destructively subtracts these values without intermediate rounding from the overlapping 32-bit single-precision elements of the ZA double-vector groups.

The double-vector group within each half of or each quarter of the ZA array is selected by the sum of the vector select register and offset range, modulo 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 2 classes: Two ZA double-vectors and Four ZA double-vectors

(FEAT_SME2)

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 | 0 | 1 | Zm | 0 | 0 | Rv | 0 | 1 | 0 | Zn | 0 | 0 | 1 | 0 | off2 | ||||||||

S |

if !IsFeatureImplemented(FEAT_SME2) then UNDEFINED; constant integer v = UInt('010':Rv); constant integer n = UInt(Zn:'0'); constant integer m = UInt(Zm:'0'); constant integer offset = UInt(off2:'0'); constant integer nreg = 2;

(FEAT_SME2)

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 | 0 | 1 | Zm | 0 | 1 | 0 | Rv | 0 | 1 | 0 | Zn | 0 | 0 | 0 | 1 | 0 | off2 | ||||||

S |

if !IsFeatureImplemented(FEAT_SME2) then UNDEFINED; constant integer v = UInt('010':Rv); constant integer n = UInt(Zn:'00'); constant integer m = UInt(Zm:'00'); constant integer offset = UInt(off2:'0'); constant integer nreg = 4;

<Wv> |
Is the 32-bit name of the vector select register W8-W11, encoded in the "Rv" field. |

<offs1> |
Is the first vector select offset, encoded as "off2" field times 2. |

<offs2> |
Is the second vector select offset, encoded as "off2" field times 2 plus 1. |

<Zn4> |
Is the name of the fourth scalable vector register of the first source multi-vector group, encoded as "Zn" times 4 plus 3. |

<Zn2> |
Is the name of the second scalable vector register of the first source multi-vector group, encoded as "Zn" times 2 plus 1. |

<Zm4> |
Is the name of the fourth scalable vector register of the second source multi-vector group, encoded as "Zm" times 4 plus 3. |

<Zm2> |
Is the name of the second scalable vector register of the second source multi-vector group, encoded as "Zm" times 2 plus 1. |

CheckStreamingSVEAndZAEnabled(); constant integer VL = CurrentVL; constant integer elements = VL DIV 32; constant integer vectors = VL DIV 8; constant integer vstride = vectors DIV nreg; constant bits(32) vbase = X[v, 32]; integer vec = (UInt(vbase) + offset) MOD vstride; bits(VL) result; vec = vec - (vec MOD 2); for r = 0 to nreg-1 constant bits(VL) op1 = Z[n+r, VL]; constant bits(VL) op2 = Z[m+r, VL]; for i = 0 to 1 constant bits(VL) op3 = ZAvector[vec + i, VL]; for e = 0 to elements-1 constant bits(16) elem1 = FPNeg(Elem[op1, 2 * e + i, 16], FPCR); constant bits(16) elem2 = Elem[op2, 2 * e + i, 16]; constant bits(32) elem3 = Elem[op3, e, 32]; Elem[result, e, 32] = FPMulAddH_ZA(elem3, elem1, elem2, FPCR); ZAvector[vec + i, VL] = result; vec = vec + vstride;

Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

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