Automated Failure Categorization

Concept

Automated Failure Categorization (AFC) is a rule-based analysis stage for RVV RTL verification that clusters failing tests by architectural symptoms, instruction context, and RVV-parameter predicates to make large failure sets easier to debug.

First seen 9/5/2026

Last seen 9/5/2026

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WIKI

Overview

Automated Failure Categorization (AFC) is a stage introduced in the open-source RVVTS-based RTL verification framework for the RISC-V Vector Extension (RVV) 1.0. It is intended to make large sets of RTL verification failures more scalable to analyze by clustering failing cases into meaningful failure-mode categories rather than leaving engineers to inspect each failing test manually.

AFC addresses a specific problem in RVV verification: RVV instructions are parameterized by runtime configuration state such as vtype, vl, vstart, element width, register grouping, and masking. This creates a large configuration space, so even after failures are isolated to individual instructions, many distinct architectural symptoms can remain.

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RELATIONSHIPS

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From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV ← introduces 100% 2e

The paper introduces the novel Automated Failure Categorization (AFC) stage.

Machine State uses → 100% 2e

AFC analyzes the extracted Machine State from the reference simulator and the DUT to cluster failures.

failure mode category introduces → 100% 2e

AFC clusters failures into meaningful failure mode categories using predefined rules.

single-instruction isolation uses → 90% 1e

AFC builds upon single-instruction isolation to further categorize failures.

LINKED ENTITIES

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From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV INTRODUCES Extracted graph relationship

Machine State USES Extracted graph relationship

failure mode category INTRODUCES Extracted graph relationship

single-instruction isolation USES Extracted graph relationship

CITATIONS

11 sources

11 citations — click to expand

[1] AFC is introduced as a novel stage in an open-source RVVTS-based RTL verification framework for RVV 1.0. From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV

[2] AFC is motivated by the large RVV configuration space and the need to analyze diverse failure modes even after single-instruction isolation. From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV

[3] The framework defines a failure mode as an equivalence class of mismatching tests sharing instruction context, a minimal predicate over RVV parameters, and the same architectural symptom. From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV

[4] AFC analyzes Machine States from the reference simulator and DUT, evaluates predefined rules sequentially, assigns the first matching failure-mode category, and uses UNKNOWN as a fallback. From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV

[5] The paper defines 29 failure-mode categories for AFC, including the fallback UNKNOWN category. From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV

[6] AFC examples include instruction validity errors, vector length and type handling errors, register value deviations, CSR deviations, deadlocks or hangs, and cross-instruction propagation. From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV

[7] For hang handling, the AraRunner creates a Machine State with an invalid last executed PC so RVVTS can process hang cases like other Machine State deviations. From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV

[8] In the Ara evaluation, AFC detected hang-category cases by checking for an invalid last executed PC in the DUT Machine State. From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV

[9] In the Ara evaluation, the framework detected more than 82,000 deviations, minimized about 97%, and clustered failures into 16 categories. From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV

[10] The Ara study reports AFC associating minimized failures with 611 instructions across 16 failure-mode categories. From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV

[11] The six largest Ara failure-mode categories account for more than 93% of all failed cases and include VREG_ONLY, VTYPE_VILL_SET_ERROR, ARA_HANG, MSTATUS_EXT_REF, EXC_INVALID_REJECT, and EXC_INVALID_ACCEPT. From Generation to Failure Categorization: An Open-Source automated RTL Verification Framework for RVV