CNTP (predicate as counter)

Counts the number of true elements in the source predicate and places the scalar result in the destination general-purpose register.

SVE2
(FEAT_SVE2p1)

if !IsFeatureImplemented(FEAT_SME2) && !IsFeatureImplemented(FEAT_SVE2p1) then UNDEFINED; constant integer esize = 8 << UInt(size); constant integer n = UInt(PNn); constant integer d = UInt(Rd); constant integer width = 2 << UInt(vl);

Assembler Symbols

<Xd>	Is the 64-bit name of the destination general-purpose register, encoded in the "Rd" field.

<PNn>

Is the name of the first source scalable predicate register, with predicate-as-counter encoding, encoded in the "PNn" field.

<T>

Is the size specifier, encoded in size:

size	<T>
00	B
01	H
10	S
11	D

<vl>

Is the vl specifier, encoded in vl:

vl	<vl>
0	VLx2
1	VLx4

Operation

if IsFeatureImplemented(FEAT_SVE2p1) then CheckSVEEnabled(); else CheckStreamingSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV esize; constant bits(PL) pred = P[n, PL]; constant bits(PL*4) mask = CounterToPredicate(pred<15:0>, PL*4); bits(64) sum = Zeros(64); constant integer limit = elements * width; for e = 0 to limit-1 if ActivePredicateElement(mask, e, esize) then sum = sum + 1; X[d, 64] = sum;

Operational information

If PSTATE.DIT is 1:

The execution time of this instruction is independent of:
- The values of the data supplied in any of its registers.
- The values of the NZCV flags.
The response of this instruction to asynchronous exceptions does not vary based on:
- The values of the data supplied in any of its registers.
- The values of the NZCV flags.

Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

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	0	1	0	0	1	0	1	size		1	0	0	0	0	0	1	0	0	0	0	vl	1	PNn				Rd