BFMLS (multiple vectors)

Multi-vector BFloat16 floating-point fused multiply-subtract

Multiply the corresponding BFloat16 floating-point elements of the two or four first and second source vectors and destructively subtract without intermediate rounding from the corresponding elements of the ZA single-vector groups. The vector numbers forming the single-vector group within each half of or each quarter of the ZA array are selected by the sum of the vector select register and immediate 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 SME2.1 ZA-targeting non-widening BFloat16 numerical behaviors.

This instruction is unpredicated.

ID_AA64SMFR0_EL1.B16B16 indicates whether this instruction is implemented.

It has encodings from 2 classes: Two ZA single-vectors and Four ZA single-vectors

Two ZA single-vectors
(FEAT_SVE_B16B16)

if !HaveSME2() || !IsFeatureImplemented(FEAT_SVE_B16B16) then UNDEFINED; integer v = UInt('010':Rv); integer n = UInt(Zn:'0'); integer m = UInt(Zm:'0'); integer offset = UInt(off3); boolean sub_op = TRUE; constant integer nreg = 2;

Four ZA single-vectors
(FEAT_SVE_B16B16)

if !HaveSME2() || !IsFeatureImplemented(FEAT_SVE_B16B16) then UNDEFINED; integer v = UInt('010':Rv); integer n = UInt(Zn:'00'); integer m = UInt(Zm:'00'); integer offset = UInt(off3); boolean sub_op = TRUE; constant integer nreg = 4;