cmpeq

SVE Compare Equal (Integer)

CMPEQ <Pd>.<T>, <Pg>/Z, <Zn>.<T>, <Zm>.<T>

Sets predicate bits where elements are equal.

Pseudocode Operation

for i = 0 to VL/esize-1
  if Pg[i] == 1
    Pd[i] ← (Zn[i, esize] == Zm[i, esize]) ? 1 : 0
  else
    Pd[i] ← 0

Example

CMPEQ p0.T, p0/m/Z, z1.s.T, z2.s.T

Encoding

Binary Layout

00100100

31:24

size

23:22

0

21

Zm

20:16

1

15

0

14

1

13

Pg

12:10

Zn

9:5

0

4

Pd

3:0

 

Format SVE Compare

Opcode 0x2400A000

Extension SVE

Operands

• Pd
  Dest Pred
• Pg
  Mask
• Zn
  First source scalable vector register (SVE)
• Zm
  Second source scalable vector register (SVE)

Related

More in SVE

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0x25008000	CMPEQ <Pd>.<T>, <Pg>/Z, <Zn>.<T>, #<imm>		A64		00100101 | size | 0 | imm5 | 1 | 0 | 0 | Pg | Zn | 0 | Pd
0x24002000	CMPEQ <Pd>.<T>, <Pg>/Z, <Zn>.<T>, <Zm>.D		A64		00100100 | size | 0 | Zm | 0 | 0 | 1 | Pg | Zn | 0 | Pd
0x2400A000	CMPEQ <Pd>.<T>, <Pg>/Z, <Zn>.<T>, <Zm>.<T>		A64		00100100 | size | 0 | Zm | 1 | 0 | 1 | Pg | Zn | 0 | Pd

Description

Compare active integer elements in the first source vector with corresponding elements in the second source vector, and place the boolean results of the specified comparison in the corresponding elements of the destination predicate. Inactive elements in the destination predicate register are set to zero. Sets the First (N), None (Z), !Last (C) condition flags based on the predicate result, and the V flag to zero.

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) operand1 = if AnyActiveElement(mask, esize) then Z[n, VL] else Zeros(VL);
bits(VL) operand2 = if AnyActiveElement(mask, esize) then Z[m, VL] else Zeros(VL);
bits(PL) result;
constant integer psize = esize DIV 8;

for e = 0 to elements-1
    integer element1 = Int(Elem[operand1, e, esize], unsigned);
    if ActivePredicateElement(mask, e, esize) then
        boolean cond;
        integer element2 = Int(Elem[operand2, e, esize], unsigned);
        case op of
            when Cmp_EQ cond = element1 == element2;
            when Cmp_NE cond = element1 != element2;
            when Cmp_GE cond = element1 >= element2;
            when Cmp_LT cond = element1 <  element2;
            when Cmp_GT cond = element1 >  element2;
            when Cmp_LE cond = element1 <= element2;
        bit pbit = if cond then '1' else '0';
        Elem[result, e, psize] = ZeroExtend(pbit, psize);
    else
        Elem[result, e, psize] = ZeroExtend('0', psize);

PSTATE.<N,Z,C,V> = PredTest(mask, result, esize);
P[d, PL] = result;