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Tandem Execution

Concept

Tandem execution is a RISC-V testing technique in which the same generated instruction sequences are run on a reference model and an implementation under test, and their execution traces are compared to detect divergence. In TestRIG, it is used as a pragmatic alternative to full formal proof of whole-processor equivalence.

First seen 5/27/2026
Last seen 6/3/2026
Evidence 3 chunks
Wiki v1

WIKI

Definition

Tandem execution is a model-comparison testing approach used in TestRIG for RISC-V implementations. TestRIG generates random instruction sequences, executes the same sequences on a model and on the implementation under test, and compares their execution traces. The source explicitly identifies this trace-comparison workflow as "tandem execution". [Tandem execution definition]

Purpose

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NEIGHBORHOOD

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RELATIONSHIPS

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TestRIG ← implements 100% 3e
TestRIG implements tandem execution by running the same instruction sequences on both a model and an implementation and comparing traces.
TestRIG ← uses 95% 1e
TestRIG checks equivalence by executing instruction sequences on both model and implementation (tandem execution).

LINKED ENTITIES

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Direct Instruction Injection complements The evidence states that TestRIG uses Direct Instruction Injection for test injection, providing instructions from the test harness rather than normal program-memory fetch.

CITATIONS

6 sources
6 citations — click to expand
[1] Tandem execution definition Randomized Testing of RISC-V CPUs using Direct Instruction Injection
[2] Purpose and limitation Randomized Testing of RISC-V CPUs using Direct Instruction Injection
[3] Trace comparison and RVFI observation Randomized Testing of RISC-V CPUs using Direct Instruction Injection
[4] Direct Instruction Injection role Randomized Testing of RISC-V CPUs using Direct Instruction Injection
[5] VEngine comparison model Randomized Testing of RISC-V CPUs using Direct Instruction Injection
[6] Scope and reported effectiveness Randomized Testing of RISC-V CPUs using Direct Instruction Injection