whilele
SVE While Less Than or Equal
Generates a predicate based on loop counter (while Xn <= Xm).
Pseudocode Operation
for i = 0 to VL/esize-1
Pd[i] ← (Xn <= Xm)Example
Encoding
Operands
-
Pd
Destination predicate register (SVE) -
Xn
Start -
Xm
Limit
Related
More in SVE
Reference
Instruction Forms
| Encoding | Instruction | ISA | Bit pattern | ||
|---|---|---|---|---|---|
| 0x25200410 | WHILELE <Pd>.<T>, <R><n>, <R><m> | A64 | 00100101 | size | 1 | Rm | 000 | sf | 0 | 1 | Rn | 1 | Pd | ||
| 0x25204418 | WHILELE <PNd>.<T>, <Xn>, <Xm>, <vl> | A64 | 00100101 | size | 1 | Rm | 01 | vl | 0 | 0 | 1 | Rn | 1 | 1 | PNd | ||
| 0x25205411 | WHILELE { <Pd1>.<T>, <Pd2>.<T> }, <Xn>, <Xm> | A64 | 00100101 | size | 1 | Rm | 0101 | 0 | 1 | Rn | 1 | Pd | 1 |
Description
Generate a predicate that starting from the lowest numbered element is true while the incrementing value of the first, signed scalar operand is less than or equal to the second scalar operand and false thereafter up to the highest numbered element. If the second scalar operand is equal to the maximum signed integer value then a condition which includes an equality test can never fail and the result will be an all-true predicate. The full width of the scalar operands is significant for the purposes of comparison, and the full width first operand is incremented by one for each destination predicate element, irrespective of the predicate result element size. The first general-purpose source register is not itself updated. The predicate result is placed in the predicate destination register. Sets the First (N), None (Z), !Last (C) condition flags based on the predicate result, and the V flag to zero.
Operation
CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
bits(PL) mask = Ones(PL);
bits(rsize) operand1 = X[n, rsize];
bits(rsize) operand2 = X[m, rsize];
bits(PL) result;
boolean last = TRUE;
constant integer psize = esize DIV 8;
for e = 0 to elements-1
boolean cond;
case op of
when Cmp_LT cond = (Int(operand1, unsigned) < Int(operand2, unsigned));
when Cmp_LE cond = (Int(operand1, unsigned) <= Int(operand2, unsigned));
last = last && cond;
bit pbit = if last then '1' else '0';
Elem[result, e, psize] = ZeroExtend(pbit, psize);
operand1 = operand1 + 1;
PSTATE.<N,Z,C,V> = PredTest(mask, result, esize);
P[d, PL] = result;