ISB Instruction synchronization barrier This instruction flushes the pipeline in the PE and is a context synchronization event. For more information, see Instruction Synchronization Barrier (ISB). 1 1 0 1 0 1 0 1 0 0 0 0 0 0 1 1 0 0 1 1 1 1 0 1 1 1 1 1 ISB {<option>|#<imm>} // no additional decoding required <option> Specifies an optional limitation on the barrier operation. Values are: SY Full system barrier operation, encoded as CRm = 0b1111. Can be omitted. All other encodings of "CRm" are reserved. The corresponding instructions execute as full system barrier operations, but must not be relied upon by software. <imm> Is an optional 4-bit unsigned immediate, in the range 0 to 15, defaulting to 15 and encoded in the "CRm" field. InstructionSynchronizationBarrier(); if IsFeatureImplemented(FEAT_BRBE) && BRBEBranchOnISB() then BRBEISB(); end; 2026-03-26 20:27:25 2026-03_rel