REV (predicate)

Reverse all elements in a predicate

Reverse the order of all elements in the source predicate and place in the destination predicate. This instruction is unpredicated.

Encoding: SVE

Variants: FEAT_SVE || FEAT_SME (FEAT_SVE || FEAT_SME)

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	0	0	0	0	1	0	1			1	1	0	1	0	0	0	1	0	0	0	0	0					0
								size															Pn					Pd

REV <Pd>.<T>, <Pn>.<T>

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
constant integer esize = 8 << UInt(size);
constant integer n = UInt(Pn);
constant integer d = UInt(Pd);

Operation

CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant bits(PL) operand = P[n, PL];
constant bits(PL) result = Reverse(operand, esize DIV 8);
P[d, PL] = result;

Explanations

<Pd>: Is the name of the destination scalable predicate register, encoded in the "Pd" field.
<T>: <Pn>: Is the name of the source scalable predicate register, encoded in the "Pn" field.

Operational Notes

If PSTATE.DIT is 1:

• The execution time of this instruction is independent of:
  • The values of the data supplied in any of its registers.
  • The values of the NZCV flags.
• The response of this instruction to asynchronous exceptions does not vary based on:
  • The values of the data supplied in any of its registers.
  • The values of the NZCV flags.