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configuration register randomization

Concept WIKI v1 · 6/1/2026

Configuration register randomization is a test-generation technique in the described RISC-V/V²PRO self-testing framework in which special vector co-processor configuration registers are assigned random settings for each executed test sequence to increase coverage of configuration states and execution modes.

Configuration register randomization is used in the self-testing framework's architecture-specific extensions for vector instruction generation. In this context, the vector co-processor exposes several special configuration registers whose settings affect instruction behavior, and the framework emits random register configurations for each executed test sequence.[1][2]

Configurations covered

The evidence describes three configuration areas that are randomized:[1]

  • Result shift for multiply vector instructions
  • Reset data source for multiply-and-accumulate vector instructions, such as an immediate value, constant zero, or a register file address
  • Reset condition for the accumulation register while long vertical vectors are processed sequentially, such as resetting once or when the x-, y-, or z-iterator increments

Testing purpose

The stated purpose of this randomization is to improve coverage of both:

  • configuration register states, and
  • the correct functionality of configured execution modes.[2]

The execution modes explicitly called out in the evidence are:

  • multiplication shift amounts,
  • multiply-accumulate reset modes, and
  • multiply-accumulate reset value configurations.[2]

Reference-model support

Because these randomized register settings affect execution semantics, the framework also extends the RISC-V twin used for reference calculation with corresponding code snippets so the expected results reflect the selected configurations.[3]

Relationship to vector instruction generation

The evidence places configuration register randomization inside an architecture-specific extension for vector instruction generation, indicating that it is one of the mechanisms used when generating randomized test sequences for the vector co-processor.[4]

References

  • [1] Special vector co-processor configuration registers and what they control
  • [2] Per-test-sequence random configuration emission for coverage
  • [3] RISC-V twin/reference-calculation support for configuration features
  • [4] Placement within architecture-specific vector instruction generation

LINKED ENTITIES

1 links
random vector instruction generation USES

CITATIONS

5 sources
5 citations
[1] Special configuration registers in the vector co-processor control the result shift in multiply vector instructions, the reset data source in multiply-and-accumulate vector instructions, and the reset condition of the accumulation register. A Self-Testing Framework for Verification and Validation of a RISC-V-Based System with a Co-processor | International Journal of Parallel Programming | Springer Nature Link
[2] For coverage of configuration register states and configured execution modes, random configurations are emitted for each executed test sequence. A Self-Testing Framework for Verification and Validation of a RISC-V-Based System with a Co-processor | International Journal of Parallel Programming | Springer Nature Link
[3] The configured execution modes explicitly include shift amounts for multiplication, reset modes for the multiply-accumulate vector instruction, and reset value configurations for multiply-accumulate vector instructions. A Self-Testing Framework for Verification and Validation of a RISC-V-Based System with a Co-processor | International Journal of Parallel Programming | Springer Nature Link
[4] To cope with these configuration-register features, corresponding code snippets were added to the RISC-V twin reference calculation. A Self-Testing Framework for Verification and Validation of a RISC-V-Based System with a Co-processor | International Journal of Parallel Programming | Springer Nature Link
[5] Configuration register randomization is described as part of an architecture-specific extension for vector instruction generation. A Self-Testing Framework for Verification and Validation of a RISC-V-Based System with a Co-processor | International Journal of Parallel Programming | Springer Nature Link