CNTP (predicate)

Set scalar to count of true predicate elements

Counts the number of active and true elements in the source predicate and places the scalar result in the destination general-purpose register. Inactive predicate elements are not counted.

313029282726252423222120191817161514131211109876543210
00100101size10000010Pg0PnRd

CNTP <Xd>, <Pg>, <Pn>.<T>

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 8 << UInt(size); constant integer g = UInt(Pg); constant integer n = UInt(Pn); constant integer d = UInt(Rd);

Assembler Symbols

<Xd>

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

<Pg>

Is the name of the governing scalable predicate register, encoded in the "Pg" field.

<Pn>

Is the name of the source scalable predicate register, encoded in the "Pn" field.

<T>

Is the size specifier, encoded in size:

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

Operation

CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV esize; constant bits(PL) mask = P[g, PL]; constant bits(PL) operand = P[n, PL]; bits(64) sum = Zeros(64); for e = 0 to elements-1 if ActivePredicateElement(mask, e, esize) && ActivePredicateElement(operand, e, esize) then sum = sum + 1; X[d, 64] = sum;

Operational information

If FEAT_SVE2 is implemented or FEAT_SME is implemented, then if PSTATE.DIT is 1:

If FEAT_SME is implemented and the PE is in Streaming SVE mode, then any subsequent instruction which is dependent on the general-purpose register written by this instruction might be significantly delayed.


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

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