GCSB Guarded Control Stack barrier This instruction generates a GCSB effect. If FEAT_GCS is not implemented, this instruction executes as a NOP. 1 1 0 1 0 1 0 1 0 0 0 0 0 0 1 1 0 0 1 0 0 0 1 0 0 1 1 1 1 1 1 1 GCSB DSYNC if !IsFeatureImplemented(FEAT_GCS) then ExecuteAsNOP(); GCSSynchronizationBarrier();