PFIRST Set the first active predicate element to true Sets the first active element in the destination predicate to true, otherwise elements from the source predicate are passed through unchanged. Sets the First (N), None (Z), !Last (C) condition flags based on the predicate result, and the V flag to zero. Green True 0 0 1 0 0 1 0 1 0 1 0 1 1 0 0 0 1 1 0 0 0 0 0 0 PFIRST <Pdn>.B, <Pg>, <Pdn>.B if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 8; constant integer g = UInt(Pg); constant integer dn = UInt(Pdn); <Pdn> Is the name of the source and destination scalable predicate register, encoded in the "Pdn" field. <Pg> Is the name of the governing scalable predicate register, encoded in the "Pg" field. CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV esize; constant bits(PL) mask = P[g, PL]; bits(PL) result = P[dn, PL]; integer first = -1; constant integer psize = esize DIV 8; for e = 0 to elements-1 if ActivePredicateElement(mask, e, esize) && first == -1 then first = e; if first >= 0 then Elem[result, first, psize] = ZeroExtend('1', psize); PSTATE.<N,Z,C,V> = PredTest(mask, result, esize); P[dn, PL] = result;