blacklisting instructions

Technique

Blacklisting instructions is a verification technique in which selected instructions are temporarily excluded from generated tests so that functional regressions can run while design modules or instruction support are still incomplete. In the cited RISC-V vector accelerator verification environment, many instructions were initially blacklisted and then gradually re-enabled as errors were fixed and missing features were implemented.

First seen 5/27/2026

Last seen 5/27/2026

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Overview

blacklisting instructions is a staged verification technique used to keep generated tests functional when parts of a design are still under development. In the cited RISC-V vector accelerator verification environment, the verification team initially blacklisted many instructions from generated tests because some design modules were still in development for much of the verification process. This allowed functional tests to run at each iteration instead of being dominated by known unsupported or incomplete instruction behavior.

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Functional Verification of a RISC-V Vector Accelerator ← uses 95% 1e

The paper uses instruction blacklisting to exclude unimplemented instructions from test generation.

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Functional Verification of a RISC-V Vector Accelerator USES Extracted graph relationship

CITATIONS

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[1] RISCV-DV generated random RISC-V assembly tests that were used to provide vector instructions for testing the VPU. source

[2] The verification team adapted RISCV-DV for RVV 0.7.1 and added generation/control features including vsetvli generation, memory-operation modifications, data-page initialization selection, and memory-address constraints. source

[3] Because some design modules were still in development, many instructions were initially blacklisted from generated tests to obtain functional tests at each iteration. source

[4] As a significant number of errors were fixed, instructions were gradually removed from the blacklist until all implemented instructions were enabled. source

[5] Some instructions were not implemented and had to be blacklisted, which artificially decreased the number of observed errors during that phase. source

[6] After the RTL team fixed more errors and finished missing features, instructions were whitelisted, causing an increase in errors found between June and September. source

[7] When an error was tentatively fixed, regressions were run before the changes could be merged. source