BRKB
Break before first true condition
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 remain unmodified or are set to zero, depending on whether merging or zeroing predication is selected. Does not set the condition flags.
Green
True
0
0
1
0
0
1
0
1
1
0
0
1
0
0
0
0
0
1
0
BRKB <Pd>.B, <Pg>/<ZM>, <Pn>.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 d = UInt(Pd);
constant boolean merging = (M == '1');
constant boolean setflags = FALSE;
<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.
<ZM>
Is the predication qualifier,
<Pn>
Is the name of the source scalable predicate register, encoded in the "Pn" 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) operand = P[n, PL];
constant bits(PL) operand2 = if merging then P[d, PL] else Zeros(PL);
boolean break = FALSE;
bits(PL) result;
constant integer psize = esize DIV 8;
for e = 0 to elements-1
constant boolean element = ActivePredicateElement(operand, e, esize);
if ActivePredicateElement(mask, e, esize) then
break = break || element;
constant bit pbit = if !break then '1' else '0';
Elem[result, e, psize] = ZeroExtend(pbit, psize);
elsif merging then
constant bit pbit = PredicateElement(operand2, e, esize);
Elem[result, e, psize] = ZeroExtend(pbit, psize);
else
Elem[result, e, psize] = ZeroExtend('0', psize);
if setflags then
PSTATE.<N,Z,C,V> = PredTest(mask, result, esize);
P[d, PL] = result;