BFMOP4S (non-widening)

BFloat16 quarter-tile outer product, subtracting

This instruction generates four independent quarter-tile BFloat16 outer products from the sub-matrices in the half-vectors of the one or two first and second source vectors and subtracts the results from the corresponding elements of a 16-bit element ZA tile.

Each of the quarter-tile outer products is generated by multiplying the SVL_H÷2 × 1 sub-matrix of BFloat16 values held in the half-vectors of the first source vectors by the 1 × SVL_H÷2 sub-matrix of BFloat16 values held in the half-vectors of the second source vectors.

The resulting quarter-tile SVL_H÷2 × SVL_H÷2 BFloat16 outer products are destructively subtracted from the destination ZA tile. This is equivalent to performing a single multiply-subtract from each of the destination tile elements.

This instruction follows SME2 ZA-targeting non-widening BFloat16 numerical behaviors.

This instruction is unpredicated.

It has encodings from 4 classes: Single and multiple vectors , Single vectors , Multiple and single vectors and Multiple vectors

Single and multiple vectors
(FEAT_SME_MOP4 && FEAT_SME_B16B16)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME_MOP4) || !IsFeatureImplemented(FEAT_SME_B16B16) then EndOfDecode(Decode_UNDEF); end; let n : integer = UInt('0'::Zn::'0'); let m : integer = UInt('1'::Zm::'0'); let nreg : integer{} = 1; let mreg : integer = 2; let da : integer = UInt(ZAda); let sub_op : boolean = TRUE;

Single vectors
(FEAT_SME_MOP4 && FEAT_SME_B16B16)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME_MOP4) || !IsFeatureImplemented(FEAT_SME_B16B16) then EndOfDecode(Decode_UNDEF); end; let n : integer = UInt('0'::Zn::'0'); let m : integer = UInt('1'::Zm::'0'); let nreg : integer{} = 1; let mreg : integer = 1; let da : integer = UInt(ZAda); let sub_op : boolean = TRUE;

Multiple and single vectors
(FEAT_SME_MOP4 && FEAT_SME_B16B16)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME_MOP4) || !IsFeatureImplemented(FEAT_SME_B16B16) then EndOfDecode(Decode_UNDEF); end; let n : integer = UInt('0'::Zn::'0'); let m : integer = UInt('1'::Zm::'0'); let nreg : integer{} = 2; let mreg : integer = 1; let da : integer = UInt(ZAda); let sub_op : boolean = TRUE;

Multiple vectors
(FEAT_SME_MOP4 && FEAT_SME_B16B16)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME_MOP4) || !IsFeatureImplemented(FEAT_SME_B16B16) then EndOfDecode(Decode_UNDEF); end; let n : integer = UInt('0'::Zn::'0'); let m : integer = UInt('1'::Zm::'0'); let nreg : integer{} = 2; let mreg : integer = 2; let da : integer = UInt(ZAda); let sub_op : boolean = TRUE;