RDFFRS

Return predicate of succesfully loaded elements, setting the condition flags

Read the first-fault register (FFR) and place active elements in the corresponding elements of the destination predicate. Inactive elements in the destination predicate register are set to zero. Sets the First (N), None (Z), !Last (C) condition flags based on the predicate result, and the V flag to zero.

This instruction is illegal when executed in Streaming SVE mode, unless FEAT_SME_FA64 is implemented and enabled.

313029282726252423222120191817161514131211109876543210
00100101010110001111000Pg0Pd
S

RDFFRS <Pd>.B, <Pg>/Z

if !IsFeatureImplemented(FEAT_SVE) then UNDEFINED; constant integer g = UInt(Pg); constant integer d = UInt(Pd); constant boolean setflags = TRUE;

Assembler Symbols

<Pd>

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

<Pg>

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

Operation

CheckNonStreamingSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant bits(PL) mask = P[g, PL]; constant bits(PL) ffr = FFR[PL]; constant bits(PL) result = ffr AND mask; if setflags then PSTATE.<N,Z,C,V> = PredTest(mask, result, 8); P[d, PL] = result;

Operational information

If FEAT_SVE2 is implemented or FEAT_SME is implemented, then if PSTATE.DIT is 1:


Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

Copyright © 2010-2024 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.