antmicro/verilator
Nov 2024 – Oct 2025
11 Months active
Languages Used
C++PythonSystemVerilogVerilogShellrstVerilog HDL
Technical Skills
Build SystemsC++Code RefactoringCompiler ToolchainsTestingVerilog/SystemVerilog
Bartłomiej Chmiel
PROFILE
Bartłomiej Chmiel
Over eleven months, Bartosz Chmiel contributed to the antmicro/verilator repository, focusing on performance, reliability, and maintainability in Verilog and SystemVerilog simulation tooling. He engineered multi-threaded simulation features, enhanced assertion handling, and improved profiling and scheduling for large-scale RTL designs. Using C++ and Python, Bartosz refactored core parsing and code generation logic, optimized DPI and hierarchical scheduling, and addressed memory management and test coverage gaps. His work included robust bug fixes in parser internals and assertion semantics, as well as code hygiene improvements, resulting in a more stable, scalable, and maintainable codebase for hardware verification and simulation workflows.
Overall Statistics
Feature vs Bugs
41%Features
Repository Contributions
34Total
Bugs
16
Commits
34
Features
11
Lines of code
8,470
Activity Months11
Your Network
102 people
Work History
October 2025
5 Commits • 2 Features
Oct 1, 2025October 2025 performance-focused summary for antmicro/verilator. This period prioritized reliability, correctness, and test coverage in assertion handling and Verilog parsing, delivering several high-impact features and robust fixes that improve user confidence and reduce runtime issues across common use cases. Highlights include improved assertion type display and test coverage, memory-management fixes in the Verilog parser for eventually[] and $past, support for simple cycle delay sequence expressions in assertion properties, and corrected termination handling for $finish inside fork-join blocks. These changes collectively reduce memory leaks, prevent deadlocks, and enhance observability and debugging during Verilator-based verification flows.
5 Commits • 2 Features
Oct 1, 2025October 2025 performance-focused summary for antmicro/verilator. This period prioritized reliability, correctness, and test coverage in assertion handling and Verilog parsing, delivering several high-impact features and robust fixes that improve user confidence and reduce runtime issues across common use cases. Highlights include improved assertion type display and test coverage, memory-management fixes in the Verilog parser for eventually[] and $past, support for simple cycle delay sequence expressions in assertion properties, and corrected termination handling for $finish inside fork-join blocks. These changes collectively reduce memory leaks, prevent deadlocks, and enhance observability and debugging during Verilator-based verification flows.
October 2025
September 2025
5 Commits • 1 Features
Sep 1, 2025September 2025 monthly summary for antmicro/verilator: Delivered substantive stability and performance enhancements across the Verilator codebase. Key outcomes include parser and semantics fixes for Verilog sequence expressions and assertion operators with added tests; preservation of clock attributes during DFG variable removal with propagation tests; and internal build/optimization improvements including profile-guided optimization for hierarchical blocks, macro modernization to std::decay_t, and separation of header and data writing in the profiler. All changes accompanied by tests, improving reliability and performance and contributing to maintainable code and faster builds.
September 2025
5 Commits • 1 Features
Sep 1, 2025September 2025 monthly summary for antmicro/verilator: Delivered substantive stability and performance enhancements across the Verilator codebase. Key outcomes include parser and semantics fixes for Verilog sequence expressions and assertion operators with added tests; preservation of clock attributes during DFG variable removal with propagation tests; and internal build/optimization improvements including profile-guided optimization for hierarchical blocks, macro modernization to std::decay_t, and separation of header and data writing in the profiler. All changes accompanied by tests, improving reliability and performance and contributing to maintainable code and faster builds.
July 2025
2 Commits
Jul 1, 2025July 2025: Profiling reliability and code quality improvements for Verilator. Fixed uninitialized PGO counters in VlPgoProfiler, expanding test coverage with cost rollover checks and introducing hierarchical worker configurations to improve profiling accuracy and robustness. Also resolved an unused-variable warning in V3Width.cpp by correcting a type cast; no functional changes. These changes enhance profiling reliability, reduce risk of misleading optimization signals, and improve maintainability, delivering clearer performance guidance and lower maintenance burden.
2 Commits
Jul 1, 2025July 2025: Profiling reliability and code quality improvements for Verilator. Fixed uninitialized PGO counters in VlPgoProfiler, expanding test coverage with cost rollover checks and introducing hierarchical worker configurations to improve profiling accuracy and robustness. Also resolved an unused-variable warning in V3Width.cpp by correcting a type cast; no functional changes. These changes enhance profiling reliability, reduce risk of misleading optimization signals, and improve maintainability, delivering clearer performance guidance and lower maintenance burden.
July 2025
June 2025
2 Commits • 1 Features
Jun 1, 2025June 2025 monthly summary for antmicro/verilator: Delivered performance and reliability improvements in the DPI path and nested hierarchical configuration handling.
June 2025
2 Commits • 1 Features
Jun 1, 2025June 2025 monthly summary for antmicro/verilator: Delivered performance and reliability improvements in the DPI path and nested hierarchical configuration handling.
May 2025
4 Commits • 1 Features
May 1, 2025May 2025 monthly summary for antmicro/verilator emphasizing reliability, visibility, and maintainability improvements in scheduling components and internal APIs.
4 Commits • 1 Features
May 1, 2025May 2025 monthly summary for antmicro/verilator emphasizing reliability, visibility, and maintainability improvements in scheduling components and internal APIs.
May 2025
April 2025
2 Commits • 1 Features
Apr 1, 2025April 2025 — Key feature delivery for antmicro/verilator: Verilator Gantt enhancements now visualize multi-threaded waiting times and profile nested hierarchical mtasks. Implemented data collection for thread schedule wait times, improved parsing/tracking of hierarchical tasks, and updated output statistics to deliver deeper performance insights. No major bugs recorded this month. Overall impact: faster, more reliable performance diagnosis and optimization for large-scale RTL simulations, with enhanced concurrency visibility. Technologies demonstrated: C++ profiling, multi-threading analysis, data collection, and visualization.
April 2025
2 Commits • 1 Features
Apr 1, 2025April 2025 — Key feature delivery for antmicro/verilator: Verilator Gantt enhancements now visualize multi-threaded waiting times and profile nested hierarchical mtasks. Implemented data collection for thread schedule wait times, improved parsing/tracking of hierarchical tasks, and updated output statistics to deliver deeper performance insights. No major bugs recorded this month. Overall impact: faster, more reliable performance diagnosis and optimization for large-scale RTL simulations, with enhanced concurrency visibility. Technologies demonstrated: C++ profiling, multi-threading analysis, data collection, and visualization.
March 2025
4 Commits • 2 Features
Mar 1, 2025March 2025 monthly summary for antmicro/verilator focusing on delivering key features, stabilizing multi-threaded simulation, and improving developer experience. Highlights include force/release handling enhancements, multi-threaded hierarchical simulation with configurable thread counts, a PGO profiling fix for hierarchical scenarios, and a documentation link correction.
4 Commits • 2 Features
Mar 1, 2025March 2025 monthly summary for antmicro/verilator focusing on delivering key features, stabilizing multi-threaded simulation, and improving developer experience. Highlights include force/release handling enhancements, multi-threaded hierarchical simulation with configurable thread counts, a PGO profiling fix for hierarchical scenarios, and a documentation link correction.
March 2025
February 2025
1 Commits • 1 Features
Feb 1, 2025February 2025 monthly summary for antmicro/verilator focusing on codebase hygiene and maintainability enhancements. Implemented Verilator Codebase Typo Corrections and Readability Improvements with a single commit (6a8f97e1847403eaa528bddd04f5566a9319ab2f). No functional changes or user-facing impact. This work improves maintainability, reduces cognitive load for future contributors, and provides a cleaner baseline for upcoming refactors and feature work. Business value includes smoother onboarding, fewer misinterpretations, and faster future changes.
February 2025
1 Commits • 1 Features
Feb 1, 2025February 2025 monthly summary for antmicro/verilator focusing on codebase hygiene and maintainability enhancements. Implemented Verilator Codebase Typo Corrections and Readability Improvements with a single commit (6a8f97e1847403eaa528bddd04f5566a9319ab2f). No functional changes or user-facing impact. This work improves maintainability, reduces cognitive load for future contributors, and provides a cleaner baseline for upcoming refactors and feature work. Business value includes smoother onboarding, fewer misinterpretations, and faster future changes.
January 2025
3 Commits • 1 Features
Jan 1, 2025January 2025 monthly summary for antmicro/verilator focused on performance improvements and correctness fixes in hierarchical DPI scheduling and V3Life features, delivering measurable business value in throughput, profiling capabilities, and design correctness across hierarchical designs.
3 Commits • 1 Features
Jan 1, 2025January 2025 monthly summary for antmicro/verilator focused on performance improvements and correctness fixes in hierarchical DPI scheduling and V3Life features, delivering measurable business value in throughput, profiling capabilities, and design correctness across hierarchical designs.
January 2025
December 2024
4 Commits • 1 Features
Dec 1, 2024December 2024: Focused on reliability, performance, and profiling for Verilator modeling. Delivered a bug fix for VlProcess handling in coroutines with splits and ensuring begin-block cleanup to prevent execution flow errors; and implemented performance/robustness improvements including inlining optimization for V3Gate, improved handling of hierarchical dependencies, and enhanced profiling tooling for complex designs. These changes reduce build and runtime instability, improve modeling accuracy, and support scalable verification for large projects.
December 2024
4 Commits • 1 Features
Dec 1, 2024December 2024: Focused on reliability, performance, and profiling for Verilator modeling. Delivered a bug fix for VlProcess handling in coroutines with splits and ensuring begin-block cleanup to prevent execution flow errors; and implemented performance/robustness improvements including inlining optimization for V3Gate, improved handling of hierarchical dependencies, and enhanced profiling tooling for complex designs. These changes reduce build and runtime instability, improve modeling accuracy, and support scalable verification for large projects.
November 2024
2 Commits
Nov 1, 2024November 2024: Delivered two critical bug fixes in antmicro/verilator focusing on symbol decoding reliability and clang attribute checking, with targeted tests and refactoring that improve CI stability and build reliability.
2 Commits
Nov 1, 2024November 2024: Delivered two critical bug fixes in antmicro/verilator focusing on symbol decoding reliability and clang attribute checking, with targeted tests and refactoring that improve CI stability and build reliability.
November 2024
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Quality Metrics
Correctness93.0%
Maintainability85.6%
Architecture85.0%
Performance81.8%
AI Usage20.0%
Skills & Technologies
Programming Languages
C++PythonShellSystemVerilogVerilogVerilog HDLrst
Technical Skills
AST ManipulationAbstract Syntax Trees (AST)Bug FixingBuild SystemsC++C++ DevelopmentCode AnalysisCode GenerationCode HygieneCode OptimizationCode RefactoringCompiler DesignCompiler DevelopmentCompiler OptimizationCompiler Toolchains
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