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CBZ

Compare and Branch on Zero compares the value in a register with zero, and conditionally branches to a label at a PC-relative offset if the comparison is equal. It provides a hint that this is not a subroutine call or return. This instruction does not affect condition flags.

313029282726252423222120191817161514131211109876543210
sf0110100imm19Rt
op

32-bit (sf == 0)

CBZ <Wt>, <label>

64-bit (sf == 1)

CBZ <Xt>, <label>

integer t = UInt(Rt); integer datasize = if sf == '1' then 64 else 32; boolean iszero = (op == '0'); bits(64) offset = SignExtend(imm19:'00', 64);

Assembler Symbols

<Wt>

Is the 32-bit name of the general-purpose register to be tested, encoded in the "Rt" field.

<Xt>

Is the 64-bit name of the general-purpose register to be tested, encoded in the "Rt" field.

<label>

Is the program label to be conditionally branched to. Its offset from the address of this instruction, in the range +/-1MB, is encoded as "imm19" times 4.

Operation

bits(datasize) operand1 = X[t]; if IsZero(operand1) == TRUE then(operand1) == iszero then BranchTo(PC[] + offset, BranchType_JMP);


Internal version only: isa v29.05, AdvSIMD v26.0, pseudocode v35.3 ; Build timestamp: 2018-06-16T09:5845

Copyright © 2010-2018 ARM Limited or its affiliates. All rights reserved. This document is Non-Confidential.

ISA_v84A_A64_xml_00bet7 (old)htmldiff from-ISA_v84A_A64_xml_00bet7(new) ISA_v84A_A64_xml_00bet7_OPT