FMLS (multiple and indexed vector)

Multi-vector floating-point fused multiply-subtract by indexed element

Multiply the indexed element of the second source vector by the corresponding floating-point elements of the two or four first source vectors and destructively subtract without intermediate rounding from the corresponding elements of the ZA single-vector groups.

The elements within the second source vector are specified using an immediate element index which selects the same element position within each 128-bit vector segment. The index range is from 0 to one less than the number of elements per 128-bit segment, encoded in 1 to 2 bits depending on the size of the element.

The single-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 , 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 single-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.

ID_AA64SMFR0_EL1.F64F64 indicates whether the double-precision variant is implemented, and ID_AA64SMFR0_EL1.F16F16 indicates whether the half-precision variant is implemented.

It has encodings from 6 classes: Two ZA single-vectors of half-precision elements , Two ZA single-vectors of single-precision elements , Two ZA single-vectors of double-precision elements , Four ZA single-vectors of half-precision elements , Four ZA single-vectors of single-precision elements and Four ZA single-vectors of double-precision elements

Two ZA single-vectors of half-precision elements
(FEAT_SME_F16F16)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME_F16F16) then EndOfDecode(Decode_UNDEF); constant integer v = UInt('010':Rv); constant integer esize = 16; constant integer n = UInt(Zn:'0'); constant integer m = UInt('0':Zm); constant integer offset = UInt(off3); constant integer index = UInt(i3h:i3l); constant integer nreg = 2;

Two ZA single-vectors of single-precision elements
(FEAT_SME2)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF); constant integer v = UInt('010':Rv); constant integer esize = 32; constant integer n = UInt(Zn:'0'); constant integer m = UInt('0':Zm); constant integer offset = UInt(off3); constant integer index = UInt(i2); constant integer nreg = 2;

Two ZA single-vectors of double-precision elements
(FEAT_SME2 && FEAT_SME_F64F64)

Decode for this encoding

if !(IsFeatureImplemented(FEAT_SME2) && IsFeatureImplemented(FEAT_SME_F64F64)) then EndOfDecode(Decode_UNDEF); constant integer v = UInt('010':Rv); constant integer esize = 64; constant integer n = UInt(Zn:'0'); constant integer m = UInt('0':Zm); constant integer offset = UInt(off3); constant integer index = UInt(i1); constant integer nreg = 2;

Four ZA single-vectors of half-precision elements
(FEAT_SME_F16F16)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME_F16F16) then EndOfDecode(Decode_UNDEF); constant integer v = UInt('010':Rv); constant integer esize = 16; constant integer n = UInt(Zn:'00'); constant integer m = UInt('0':Zm); constant integer offset = UInt(off3); constant integer index = UInt(i3h:i3l); constant integer nreg = 4;

Four ZA single-vectors of single-precision elements
(FEAT_SME2)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF); constant integer v = UInt('010':Rv); constant integer esize = 32; constant integer n = UInt(Zn:'00'); constant integer m = UInt('0':Zm); constant integer offset = UInt(off3); constant integer index = UInt(i2); constant integer nreg = 4;

Four ZA single-vectors of double-precision elements
(FEAT_SME2 && FEAT_SME_F64F64)

Decode for this encoding

if !(IsFeatureImplemented(FEAT_SME2) && IsFeatureImplemented(FEAT_SME_F64F64)) then EndOfDecode(Decode_UNDEF); constant integer v = UInt('010':Rv); constant integer esize = 64; constant integer n = UInt(Zn:'00'); constant integer m = UInt('0':Zm); constant integer offset = UInt(off3); constant integer index = UInt(i1); constant integer nreg = 4;