PEXT (predicate pair)

Predicate extract pair from predicate-as-counter

This instruction converts the source predicate-as-counter into a four register wide predicate-as-mask, and copies the two portions of the mask value selected by the portion index to the two destination predicate registers. A portion corresponds to a one predicate register fraction of the wider predicate-as-mask value.

SVE2
(FEAT_SME2 || FEAT_SVE2p1)

313029282726252423222120191817161514131211109876543210
00100101size1000000111010i1PNn1Pd

Encoding

PEXT { <Pd1>.<T>, <Pd2>.<T> }, <PNn>[<imm>]

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME2) && !IsFeatureImplemented(FEAT_SVE2p1) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let n : integer = UInt('1'::PNn); let d0 : integer = UInt(Pd); let d1 : integer = (UInt(Pd) + 1) MOD 16; let part : integer = UInt(i1);

Assembler Symbols

<Pd1>

Is the name of the first destination scalable predicate register, encoded in the "Pd" field.

<T>

Is the size specifier, encoded in size:

size <T>
00 B
01 H
10 S
11 D
<Pd2>

Is the name of the second destination scalable predicate register, encoded in the "Pd" field.

<PNn>

Is the name of the first source scalable predicate register PN8-PN15, with predicate-as-counter encoding, encoded in the "PNn" field.

<imm>

Is the portion index, in the range 0 to 1, encoded in the "i1" field.


2025-09_diff_tag 2025-11-28 16:29:05

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