Arm® A64 Instruction Set Architecture: Future Architecture Technologies in the A architecture profile

BRKPA, BRKPAS

Break after first true condition, propagating from previous partition.

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 and 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. Optionally sets the First (N), None (Z), !Last (C) condition flags based on the predicate result, and the V flag to zero.

It has encodings from 2 classes: Not setting the condition flags and Setting the condition flags

Not setting the condition flags

if !HaveSVE() then UNDEFINED;
integer esize = 8;
integer g = UInt(Pg);
integer n = UInt(Pn);
integer m = UInt(Pm);
integer d = UInt(Pd);
boolean setflags = FALSE;

Setting the condition flags

if !HaveSVE() then UNDEFINED;
integer esize = 8;
integer g = UInt(Pg);
integer n = UInt(Pn);
integer m = UInt(Pm);
integer d = UInt(Pd);
boolean setflags = TRUE;

Assembler Symbols

CheckSVEEnabled();
integer elements = VL DIV esize;
bits(PL) mask = P[g];
bits(PL) operand1 = P[n];
bits(PL) operand2 = P[m];
bits(PL) result;
boolean last = (LastActive(mask, operand1, 8) == '1');

for e = 0 to elements-1
    if ElemP[mask, e, 8] == '1' then
        ElemP[result, e, 8] = if last then '1' else '0';
        last = last && (ElemP[operand2, e, 8] == '0');
    else
        ElemP[result, e, 8] = '0';

if setflags then
    PSTATE.<N,Z,C,V> = PredTest(mask, result, esize);
P[d] = result;