abs

SVE Absolute Value

ABS <Zdn>.<T>, <Pg>/M, <Zdn>.<T>

Calculates absolute value of integers.

Details

SVE absolute value: computes the element-wise absolute value of signed integers in Zdn, writing results back to Zdn under predicate mask control (Pg). Only elements where the predicate is active are updated; inactive elements retain their original values. No condition flags are affected. This is an AArch64-only instruction requiring SVE support.

Pseudocode Operation

for e = 0 to VL/getElementSize(T)-1
  if Pg[e] == 1 then
    Zdn[e] ← abs_signed(Zdn[e])
  end if
end for

Example

ABS z0.s.T, p0/m/M, z0.s.T

Encoding

Binary Layout
00000100
size
010
11
0
101
Pg
Zn
Zd
 
Format SVE Integer Unary
Opcode 0x0416A000
Extension SVE

Operands

  • Zdn
    Dest/Src
  • Pg
    Mask

Reference (Arm A64 ISA)

Instruction Forms

Encoding Instruction ISA Bit pattern
0x5AC02000 ABS <Wd>, <Wn> A64 0 | 1 | 0 | 11010110 | 00000 | 001000 | Rn | Rd
0xDAC02000 ABS <Xd>, <Xn> A64 1 | 1 | 0 | 11010110 | 00000 | 001000 | Rn | Rd
0x5EE0B800 ABS D<d>, D<n> A64 01 | 0 | 11110 | 11 | 10000 | 01011 | 10 | Rn | Rd
0x0E20B800 ABS <Vd>.<T>, <Vn>.<T> A64 0 | Q | 0 | 01110 | size | 10000 | 01011 | 10 | Rn | Rd
0x0416A000 ABS <Zd>.<T>, <Pg>/M, <Zn>.<T> A64 00000100 | size | 010 | 11 | 0 | 101 | Pg | Zn | Zd

Description

Compute the absolute value of the signed integer in each active element of the source vector, and place the results in the corresponding elements of the destination vector. Inactive elements in the destination vector register remain unmodified.

Operation

CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
bits(PL) mask = P[g, PL];
bits(VL) operand = if AnyActiveElement(mask, esize) then Z[n, VL] else Zeros(VL);
bits(VL) result = Z[d, VL];

for e = 0 to elements-1
    if ActivePredicateElement(mask, e, esize) then
        integer element = SInt(Elem[operand, e, esize]);
        element = Abs(element);
        Elem[result, e, esize] = element<esize-1:0>;

Z[d, VL] = result;