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Kostiantyn Liepieshov

PROFILE

Kostiantyn Liepieshov

Worked extensively on compiler and distributed systems infrastructure across openxla/xla and Intel-tensorflow/tensorflow, focusing on sharding, layout propagation, and performance optimization for large-scale machine learning workloads. Leveraged C++ and MLIR to refactor core data structures, streamline memory management, and enhance translation pipelines between HLO, MLIR, and StableHLO. Delivered features such as tuple sharding, dynamic shape memory management, and efficient computation lookup, while addressing bugs in layout ordering and sharding correctness. Improved test coverage and cross-repo consistency, enabling safer optimizations and more reliable distributed execution. Demonstrated depth in algorithm design, code refactoring, and backend development for ML frameworks.

Overall Statistics

Feature vs Bugs

77%Features

Repository Contributions

39Total
Bugs
6
Commits
39
Features
20
Lines of code
2,476
Activity Months11

Work History

May 2026

9 Commits • 2 Features

May 1, 2026

May 2026 Monthly Summary for openxla/xla: Focused on performance, stability, and correctness in HLO reachability, fusion, and layout tooling, delivering measurable improvements to runtime efficiency and build-time stability. Key features delivered: - HLO Reachability and Fusion Performance Improvements: Refactored HloReachabilityMap to std::vector for per-computation graphs and read-only processing; introduced bulk reachability updates in CopyRemoval via UpdateMultipleInstructions; optimized propagation in MultiOutputFusion with early-exit when unnecessary updates; improved HloValue::IsRootOf by comparing to the computation root; deferred embedded computation removal during fusion with a final RemoveUnusedComputations pass for safe cleanup. - CallGraph and LayoutAssignment Stability and Compile-time Improvements: Refactored CallGraph to use vector instead of hash_map to boost compile time; rebuilt call graph after cloning computations in LayoutAssignment to maintain correctness; addressed dependency fixes including missing include for HloModule. Major bugs fixed and robustness gains: - Reduced redundant reachability recomputation and tightened correctness in the fusion/reachability pipeline; ensured correctness when computations are cloned and embedded computations are deferred for removal. - Safer cleanup of unused computations, preventing premature removal during fusion passes and ensuring end-of-pass cleanup. Overall impact and accomplishments: - Faster fusion and graph processing with lower overhead, improved runtime efficiency, and more deterministic performance. - Increased stability and correctness in CallGraph/LayoutAssignment flows and within embedded computation handling. - Clearer maintenance path enabled by data-structure changes (vector-based) and safer removal patterns. Technologies/skills demonstrated: - C++ refactoring and STL data structures (vector over hash_map), per-computation graph processing, and bulk update techniques. - Performance-oriented algorithm design for reachability propagation and fusion sequencing. - Build-time optimization and dependency correctness across the HLO graph tooling.

April 2026

6 Commits • 4 Features

Apr 1, 2026

April 2026: Delivered cross-repo performance improvements and sharding management enhancements in OpenXLA and TensorFlow bridges. Key work focused on optimizing computation lookup, memory reservation sizing, and simplifying sharding configuration handling to improve throughput, memory efficiency, and maintainability across large computation graphs.

March 2026

2 Commits • 2 Features

Mar 1, 2026

March 2026 monthly summary focused on delivering value-range analysis enhancements for fused computations and improving parameter handling in two major codebases, Intel-tensorflow/xla and ROCm/tensorflow-upstream. The work emphasizes business value through safer optimizations, better code generation, and reduced risk of misoptimization when parameters flow through fused operations.

February 2026

1 Commits • 1 Features

Feb 1, 2026

February 2026 monthly performance summary for Intel-tensorflow/xla: Key development focused on dynamic shape memory management within the HloEvaluator and reinforcing memory operation reliability for large-scale workloads. Delivered a new Dynamic Shape Memory Management capability and associated testing, plus a targeted fix for dynamic shape metadata memcpy. These changes collectively improve memory predictability, scalability, and performance for dynamic-shaped inputs in production models.

November 2025

2 Commits

Nov 1, 2025

Month: 2025-11 — concise summary focusing on business value and technical achievements. Key deliverables include debugging layout ordering logic to ignore irrelevant split_configs, ensuring correctness and stability in performance-critical code paths across two major repositories. This work reduces incorrect minor-to-major ordering results and mitigates downstream misoptimizations in layout decisions.

October 2025

6 Commits • 4 Features

Oct 1, 2025

October 2025 monthly summary for Intel-tensorflow/tensorflow focusing on distributed execution improvements and stability. Key outcomes include sharding and layout propagation improvements across nested functions and MPMD, adoption of device default layouts for CopyArraysOp outputs in IFRT IR program, standardization of SparseActivationsUnstack outputs in MLIR-to-HLO, configurable StableHLO export option addMissingShardingToControlFlow, and test readability improvements for HLO strings in C++ tests. Major bugs fixed include relayout propagation fix for MPMD and ensuring custom calls for SparseActivationsUnstack always return a tuple, reducing graph generation inconsistencies and runtime errors. These efforts deliver business value through more reliable distributed training/inference, higher graph correctness, and improved developer productivity.

September 2025

2 Commits • 1 Features

Sep 1, 2025

2025-09 monthly summary for Intel-tensorflow/tensorflow: Delivered MLIR HLO Translation Improvements focused on parameter replication handling for tuple arguments and removal of duplicated passes in reshape algebraic simplification. These changes corrected replication aggregation during MLIR HLO-to-HLO translation and eliminated redundant computations, resulting in a more reliable and faster translation pipeline.

August 2025

1 Commits • 1 Features

Aug 1, 2025

Summary for 2025-08: Delivered targeted improvements to the XLA compiler path in Intel-tensorflow/tensorflow by introducing optional sharding management for MHLO to HLO conversion, with a focused bug fix on infeed/outfeed sharding. This work enhances data processing efficiency and device allocation during tensor operations, improving runtime performance and reliability for Intel-backed ML workloads.

July 2025

4 Commits • 3 Features

Jul 1, 2025

July 2025 performance summary for Intel-tensorflow/tensorflow. Focused on delivering robustness, data-management improvements, and configurable deployment options to support scalable ML workloads. Key features delivered: - Tuple Sharding for Tensor Operations: introduced tuple-based sharding to improve data management and performance for multi-dimensional tensor operations. - HLO to MLIR/MHLO Translation: Layout Handling Improvements: standardized default layouts for dense constants during HLO->MLIR export and enforced correct layout attributes during HLO->MHLO export, with presence checks and export changes. - Shardy Support Flag for TPU Embedding Configuration: added a configuration flag to enable Shardy support in TPU embedding, enabling custom partitioning options and greater configurability. Overall impact and accomplishments: - Improved runtime performance and data handling for complex tensor workloads. - Increased correctness and robustness of translation/export paths between HLO, MLIR, and MHLO. - Enhanced deployment flexibility for TPU embeddings through configurable partitioning options, enabling experimentation and optimized resource usage. Technologies and skills demonstrated: - Tuple-based sharding design and integration with tensor creation workflows. - HLO/MLIR/MHLO translation pipelines, including layout management, attribute validation, and export wiring. - Configurability patterns for TPU embeddings (feature flag integration). - Commit-driven development with clear traceability of changes to sharding, layout handling, and TPU configuration.

June 2025

3 Commits • 1 Features

Jun 1, 2025

June 2025 monthly summary for Intel-tensorflow/tensorflow. This period delivered critical correctness improvements and foundational sharding capabilities, driving business value by preserving backend configurations, enabling Shardy-based optimizations, and improving tensor data handling across translation boundaries. Key outcomes include: 1) backend_config preservation during HloToStablehlo translation; 2) XLA Shardy framework integration via a new C API for passes/pipelines; 3) implemented tuple sharding to optimize multi-output tensor scenarios. These changes reduce risk, improve reproducibility, and lay groundwork for performance gains in distributed workloads.

April 2025

3 Commits • 1 Features

Apr 1, 2025

April 2025 monthly summary for ROCm/XLA and JAX work streams. Focused on delivering features that improve cross-framework sharding correctness, and on fixing edge-case export_module bugs to increase reliability and test coverage across the ROCm/xla, ROCm/jax, and jax-ml/jax repositories.

Activity

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Quality Metrics

Correctness92.6%
Maintainability86.6%
Architecture89.8%
Performance85.4%
AI Usage22.6%

Skills & Technologies

Programming Languages

C++MLIRPythonprotobuf

Technical Skills

API developmentAlgorithm DesignAlgorithm OptimizationBug FixingC++C++ developmentC++ programmingCode ExportCode RefactoringCompiler DevelopmentCompiler InternalsCompiler designData StructuresDistributed SystemsHLO

Repositories Contributed To

7 repos

Overview of all repositories you've contributed to across your timeline

Intel-tensorflow/tensorflow

Jun 2025 Apr 2026
6 Months active

Languages Used

C++protobufMLIR

Technical Skills

API developmentC++C++ developmentCompiler designTensorFlowXLA

openxla/xla

Nov 2025 May 2026
3 Months active

Languages Used

C++

Technical Skills

C++software designunit testingAlgorithm DesignC++ developmentC++ programming

ROCm/tensorflow-upstream

Nov 2025 Mar 2026
2 Months active

Languages Used

C++

Technical Skills

C++ developmentsoftware designunit testingC++ programmingalgorithm designperformance optimization

Intel-tensorflow/xla

Feb 2026 Mar 2026
2 Months active

Languages Used

C++

Technical Skills

C++memory managementperformance optimizationalgorithm designunit testing

ROCm/xla

Apr 2025 Apr 2025
1 Month active

Languages Used

C++MLIR

Technical Skills

Compiler DevelopmentDistributed SystemsMLIRXLA

ROCm/jax

Apr 2025 Apr 2025
1 Month active

Languages Used

Python

Technical Skills

Bug FixingCode ExportShardingTesting

jax-ml/jax

Apr 2025 Apr 2025
1 Month active

Languages Used

Python

Technical Skills

Bug FixingCode RefactoringTesting