Itanium processors execute several instructions in parallel. Instructions that are allowed to execute in parallel are organized in instruction groups. An instruction group is a set of consecutive instructions that should have no interdependencies. The instruction group is terminated by a stop (;;). IAS supports explicit stops as defined in the IntelŪ ItaniumŪ Architecture Assembly Language Reference Guide.
IAS checks for data dependencies in instruction groups. An example of a data dependency is a write instruction following a read instruction to the same register. For more details on dependency violations, see Dependency Violations and Assembly Modes.