CNTP (predicate as counter)

Set scalar to count from predicate-as-counter

This instruction counts the number of true elements in the source predicate, up to the total number of elements in two or four vectors, and places the scalar result in the destination general-purpose register.

SVE2 class

(FEAT_SME2 || FEAT_SVE2p1)

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
													opc

Encoding

CNTP <Xd>, <PNn>.<T>, <vl>

Decode

if !IsFeatureImplemented(FEAT_SME2) && !IsFeatureImplemented(FEAT_SVE2p1) then EndOfDecode(Decode_UNDEF); 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 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 maxelements = elements * width; for e = 0 to maxelements-1 if ActivePredicateElement(mask, e, esize) then sum = sum + 1; X[d, 64] = sum;