← Home

PTEST

Set condition flags for predicate

This instruction sets the First (N), None (Z), and !Last (C) condition flags based on the predicate source register, and sets the V flag to zero.

SVE class

(FEAT_SVE || FEAT_SME)

313029282726252423222120191817161514131211109876543210
001001010101000011Pg0Pn00000
opSopc2

Encoding

PTEST <Pg>, <Pn>.B

Decode

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); constant integer esize = 8; constant integer g = UInt(Pg); constant integer n = UInt(Pn);

Assembler Symbols

<Pg>

Is the name of the governing scalable predicate register, encoded in the "Pg" field.

<Pn>

Is the name of the source scalable predicate register, encoded in the "Pn" field.

Operation

CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant bits(PL) mask = P[g, PL]; constant bits(PL) result = P[n, PL]; PSTATE.<N,Z,C,V> = PredTest(mask, result, esize);

Operational information

If FEAT_SME is implemented and the PE is in Streaming SVE mode, then any subsequent instruction which is dependent on the predicate register written by this instruction might be significantly delayed.


Version 2025.09 — Copyright © 2010-2025 Arm Limited or its affiliates.

This site is provided as a community resource and is NOT affiliated with nor endorsed by Arm Limited.