Definition

Lock-Step Compare is a processor verification technique in which the RTL implementation and a golden reference model are run in parallel, with results compared at instruction retirement. Its purpose is early bug detection by identifying behavioral mismatches as soon as they appear.

Role in RISC-V verification

In RISC-V verification flows, Lock-Step Compare is used to check that an RTL implementation behaves consistently with a reference model. The evidence describes this comparison point specifically as instruction retirement, which provides an architecturally meaningful boundary for detecting mismatches.

Use with ImperasDV

ImperasDV integrates fast RISC-V reference models into verification flows and enables lock-step comparison of RTL against a golden reference model at instruction retirement. The cited material also states that combining architecturally self-checking tests with Lock-Step Compare in ImperasDV helps engineers identify mismatches immediately, simplifying root-cause analysis.

Verification benefits

Lock-Step Compare contributes to debug efficiency by exposing mismatches during execution rather than only after a full test completes. In the described RISC-V verification methodology, this immediate mismatch identification supports faster root-cause analysis when used with ImperasDV and self-checking tests.