Systematic validation of pipeline interlock for superscalar microarchitectures

The paper presents a new approach to microarchitecture validation that adopts a paradigm analogous to that of automatic test pattern generation (ATPG) for digital logic testing. In this approach, the microarchitecture is rigorously specified in a set of machine description files. Based on these files, all possible pipeline hazards can be systematically identified Using this hazard list (analogous to a fault list for ATPG), specific sequences of instructions (analogous to test patterns) are automatically generated and constitute the test program. The execution of this test program validates the correct detection and resolution of all interinstruction dependences by the microarchitecture's pipeline interlock mechanism. Actual software tools have been developed for the automatic construction of the hazard list and the automatic generation of the test sequences. These explicitly generated can achieve higher sequences coverage in fewer cycles than adhoc approaches. 100% coverage of the hazard list can be ensured. These tools have been applied to four contemporary superscalar processors, namely the Alpha AXP 21064 and 21164 microprocessors, and the PowerPC 601 and 620 microprocessors.<>