BRKPBS
Break before first true condition, propagating from previous partition and setting the condition flags
If the last active element of the first source predicate is false then set the destination predicate to all-false. Otherwise sets destination predicate elements up to but not including the first active and true source element to true, then sets subsequent elements to false. 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.
Green
True
0
0
1
0
0
1
0
1
0
1
0
0
1
1
0
1
BRKPBS <Pd>.B, <Pg>/Z, <Pn>.B, <Pm>.B
if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED;
constant integer esize = 8;
constant integer g = UInt(Pg);
constant integer n = UInt(Pn);
constant integer m = UInt(Pm);
constant integer d = UInt(Pd);
constant boolean setflags = TRUE;
<Pd>
Is the name of the destination scalable predicate register, encoded in the "Pd" field.
<Pg>
Is the name of the governing scalable predicate register, encoded in the "Pg" field.
<Pn>
Is the name of the first source scalable predicate register, encoded in the "Pn" field.
<Pm>
Is the name of the second source scalable predicate register, encoded in the "Pm" 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];
constant bits(PL) operand1 = P[n, PL];
constant bits(PL) operand2 = P[m, PL];
bits(PL) result;
boolean last = (LastActive(mask, operand1, 8) == '1');
for e = 0 to elements-1
if ActivePredicateElement(mask, e, 8) then
last = last && (!ActivePredicateElement(operand2, e, 8));
constant bit pbit = if last then '1' else '0';
Elem[result, e, 1] = ZeroExtend(pbit, 1);
else
Elem[result, e, 1] = ZeroExtend('0', 1);
if setflags then
PSTATE.<N,Z,C,V> = PredTest(mask, result, esize);
P[d, PL] = result;