FADD (vectors, predicated) -- A64

This instruction adds active floating-point elements of the first source vector to the corresponding floating-point elements of the second source vector, and destructively places the results in the corresponding elements of the first source vector. Inactive elements in the destination vector register remain unmodified.

SVE
(FEAT_SVE || FEAT_SME)

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let g : integer = UInt(Pg); let dn : integer = UInt(Zdn); let m : integer = UInt(Zm);

Assembler Symbols

<Zdn>

Is the name of the first source and destination scalable vector register, encoded in the "Zdn" field.

<T>

Is the size specifier, encoded in size:

size	<T>
01	H
10	S
11	D

<Pg>	Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field.

<Zm>	Is the name of the second source scalable vector register, encoded in the "Zm" field.

Operation

CheckSVEEnabled(); let VL : integer{} = CurrentVL(); let PL : integer{} = VL DIV 8; let elements : integer = VL DIV esize; let mask : bits(PL) = P{}(g); let operand1 : bits(VL) = Z{}(dn); let operand2 : bits(VL) = if AnyActiveElement{PL}(mask, esize) then Z{VL}(m) else Zeros{VL}; var result : bits(VL); for e = 0 to elements-1 do let element1 : bits(esize) = operand1[e*:esize]; if ActivePredicateElement{PL}(mask, e, esize) then let element2 : bits(esize) = operand2[e*:esize]; result[e*:esize] = FPAdd{esize}(element1, element2, FPCR()); else result[e*:esize] = element1; end; end; Z{VL}(dn) = result;

Operational information

This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is CONSTRAINED UNPREDICTABLE:

The MOVPRFX can be predicated or unpredicated.
A predicated MOVPRFX must use the same governing predicate register as this instruction.
A predicated MOVPRFX must use the larger of the destination element size and first source element size in the preferred disassembly of this instruction.
The MOVPRFX must specify the same destination register as this instruction.
The destination register must not refer to architectural register state referenced by any other source operand register of this instruction.

2026-03_rel 2026-03-26 20:48:11

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
0	1	1	0	0	1	0	1	!= 00		0	0	0	0	0	0	1	0	0	Pg			Zm					Zdn
								size				opc