
João De Sousa engineered advanced compiler infrastructure and backend optimizations for the tenstorrent/tt-mlir and tt-metal repositories, focusing on memory-efficient tensor operations and robust test frameworks. He developed MLIR-based lowering pipelines, introduced elementwise fusion with spill-and-scratch memory management, and implemented profiling instrumentation for distributed systems. Using C++, Python, and MLIR, João delivered features such as multicast-aware scheduling, loop initialization hoisting, and configurable stream buffering, addressing both performance and maintainability. His work included end-to-end testing, debugging instrumentation, and documentation improvements, resulting in deeper reliability and scalability for high-throughput tensor workloads and streamlined development across complex hardware-software integration points.
March 2026 performance summary for tenstorrent/tt-mlir focusing on D2M pipeline efficiency and correctness. Delivered a comprehensive D2M Elementwise Fusion workflow with an integrated Spill & Scratch mechanism, enabling adjacent d2m.generic ops to be fused into a single compute region while managing intermediate tile storage within L1 scratch. Implemented DST-aware tiling and routing to support fused paths (including f32/SFPU routing) and extended DST register allocation to maximize hardware utilization. Introduced a new coordination primitive, d2m.unpack_stall_on_pack, to synchronize PACK/UNPACK in fused regions. Expanded the test suite with targeted lit tests and a Python golden test to validate correctness and performance improvements.
March 2026 performance summary for tenstorrent/tt-mlir focusing on D2M pipeline efficiency and correctness. Delivered a comprehensive D2M Elementwise Fusion workflow with an integrated Spill & Scratch mechanism, enabling adjacent d2m.generic ops to be fused into a single compute region while managing intermediate tile storage within L1 scratch. Implemented DST-aware tiling and routing to support fused paths (including f32/SFPU routing) and extended DST register allocation to maximize hardware utilization. Introduced a new coordination primitive, d2m.unpack_stall_on_pack, to synchronize PACK/UNPACK in fused regions. Expanded the test suite with targeted lit tests and a Python golden test to validate correctness and performance improvements.
January 2026 performance summary for tenstorrent/tt-mlir. Delivered significant D2M path optimizations focused on memory efficiency and grid utilization for high aspect ratio tensors. Implemented a 1D matrix multiplication heuristic with broader lowering changes, including fixes for grid tensor lowering, multicast support for both 2D and 1D, and adjustments to CoreIndexOp to improve grid virtualization mapping. Hardened device grid initialization by hard-coding CB shapes to cover the full device grid, improving predictability and scalability. Added tests validating the new paths. Overall, these changes set the foundation for higher throughput in D2M tensor operations and reduce memory pressure in demanding workloads.
January 2026 performance summary for tenstorrent/tt-mlir. Delivered significant D2M path optimizations focused on memory efficiency and grid utilization for high aspect ratio tensors. Implemented a 1D matrix multiplication heuristic with broader lowering changes, including fixes for grid tensor lowering, multicast support for both 2D and 1D, and adjustments to CoreIndexOp to improve grid virtualization mapping. Hardened device grid initialization by hard-coding CB shapes to cover the full device grid, improving predictability and scalability. Added tests validating the new paths. Overall, these changes set the foundation for higher throughput in D2M tensor operations and reduce memory pressure in demanding workloads.
2025-11 monthly summary for Tenstorrent MLIR development: Delivered the Loop Initialization Hoisting Optimization pass in tt-mlir. Established analysis scaffolding, a mapping of loops to init operations, and a conservative conflict model to safely hoist initialization calls. Implemented a two-pass kernel walkthrough to determine safe lift locations and prepared test scaffolding and validation plan for future improvements. This foundational optimization aims to reduce redundant inits, lower runtime overhead, and improve kernel throughput across MLIR pipelines.
2025-11 monthly summary for Tenstorrent MLIR development: Delivered the Loop Initialization Hoisting Optimization pass in tt-mlir. Established analysis scaffolding, a mapping of loops to init operations, and a conservative conflict model to safely hoist initialization calls. Implemented a two-pass kernel walkthrough to determine safe lift locations and prepared test scaffolding and validation plan for future improvements. This foundational optimization aims to reduce redundant inits, lower runtime overhead, and improve kernel throughput across MLIR pipelines.
Monthly summary for 2025-10 focused on delivering observable debugging improvements in ttkernel and strengthening CI/test stability for tenstorrent/tt-mlir. Key features delivered improved debugging visibility for Circular Buffers and stabilized CI/test workflows, enabling faster issue resolution and more reliable releases. Key achievements: - Circular Buffer Debugging Enhancements in ttkernel: added detailed CB value printing to ttkernel.dprint; compute-thread prints include full CB details, data-movement threads print only the CB ID; improves debugging visibility and stability. Commits: f00a11e2cfebe65c4b342c2596e880804e247c99 and e8d05138b74a0c03b1ef4d5ae0d71b76e0a3ba8a. - CI/Test stability improvements: constrain inputs for TF32-friendly golden reduction tests and adjust test setup to use TF32 ranges; and fix ttrt run.py to correctly pass atol/rtol by switching from dictionary-like access to argument-like access. Commits: 007801d4af6ac7dcaadaf38e215fe6bdad342e47 and 454a38865ea4f067fe18e1d5d7e895513b1078c0. - Test coverage and reliability: updated tests to cover changes introduced by CB printing and CI/test stability work, ensuring regression safety. - Cross-cutting skills demonstrated: low-level debugging instrumentation, MLIR/tti kernel observability, Python tooling for test configuration, and CI reliability engineering. Overall impact: The month delivered measurable improvements in debugging visibility for complex circular-buffer scenarios and a more stable CI/test pipeline, contributing to faster diagnosis of crashes or hangs and more predictable release cycles for tt-mlir.
Monthly summary for 2025-10 focused on delivering observable debugging improvements in ttkernel and strengthening CI/test stability for tenstorrent/tt-mlir. Key features delivered improved debugging visibility for Circular Buffers and stabilized CI/test workflows, enabling faster issue resolution and more reliable releases. Key achievements: - Circular Buffer Debugging Enhancements in ttkernel: added detailed CB value printing to ttkernel.dprint; compute-thread prints include full CB details, data-movement threads print only the CB ID; improves debugging visibility and stability. Commits: f00a11e2cfebe65c4b342c2596e880804e247c99 and e8d05138b74a0c03b1ef4d5ae0d71b76e0a3ba8a. - CI/Test stability improvements: constrain inputs for TF32-friendly golden reduction tests and adjust test setup to use TF32 ranges; and fix ttrt run.py to correctly pass atol/rtol by switching from dictionary-like access to argument-like access. Commits: 007801d4af6ac7dcaadaf38e215fe6bdad342e47 and 454a38865ea4f067fe18e1d5d7e895513b1078c0. - Test coverage and reliability: updated tests to cover changes introduced by CB printing and CI/test stability work, ensuring regression safety. - Cross-cutting skills demonstrated: low-level debugging instrumentation, MLIR/tti kernel observability, Python tooling for test configuration, and CI reliability engineering. Overall impact: The month delivered measurable improvements in debugging visibility for complex circular-buffer scenarios and a more stable CI/test pipeline, contributing to faster diagnosis of crashes or hangs and more predictable release cycles for tt-mlir.
In September 2025, TT-MLIR delivered improvements in profiling observability, end-to-end validation, and buffering configurability. D2M profiling integration now automatically inserts device-zone scopes for Tracy and includes an end-to-end pytest validating profiling data after ttrt perf on ttm flatbuffers. In TTMetal, the affine loop coalescing pass was replaced with the affine LICM pass to ensure loop-invariant code is moved out of loops. A new pipeline option exposes num-stream-buffers to enable variable buffering in the allocator and frame buffer generation, supported by tests and rewriters. Collectively these changes improve profiling reliability, optimization correctness, and runtime tunability, driving measurable performance and observability gains.
In September 2025, TT-MLIR delivered improvements in profiling observability, end-to-end validation, and buffering configurability. D2M profiling integration now automatically inserts device-zone scopes for Tracy and includes an end-to-end pytest validating profiling data after ttrt perf on ttm flatbuffers. In TTMetal, the affine loop coalescing pass was replaced with the affine LICM pass to ensure loop-invariant code is moved out of loops. A new pipeline option exposes num-stream-buffers to enable variable buffering in the allocator and frame buffer generation, supported by tests and rewriters. Collectively these changes improve profiling reliability, optimization correctness, and runtime tunability, driving measurable performance and observability gains.
Monthly summary for 2025-08 covering tt-mlir repo work. Delivered key feature testing and distributed profiling fixes that enhance reliability, performance instrumentation, and support for multi-device deployments. Key features delivered: - Semaphore Operation Testing and Cleanup: Implemented lit tests for semaphore semantics in the ttir->ttkernel path, refactored semaphore_set to remove an unused increment flavor, and added comprehensive tests for local set, remote increment, multicast set, and wait operations with/without reset (commit a80f5320cf5f8b355e7aee6dd83e3d53ecac4dc0). Major bugs fixed: - Distributed Profiling Stabilization for Multi-Device / MeshDevice: Refactored the profiling mechanism to correctly handle multi-device runtime IDs; separated host metadata population from results gathering; ensured program IDs are populated for multi-device programs, restoring and improving profiling functionality in a distributed environment (commit 291334c01d880402fd13a61e7628179862d6682f). Overall impact and accomplishments: - Improved test coverage and reliability for semaphore operations. - Restored and improved profiling accuracy and stability across distributed multi-device configurations, enabling better performance analysis and faster debugging. Technologies/skills demonstrated: - Lit-based testing for low-level synchronization primitives; test-driven development. - Code refactoring (semaphore_set cleanup) and test integration. - Distributed profiling instrumentation, multi-device runtime IDs, host metadata separation, and program ID population. - Strong focus on business value: higher confidence in correctness, faster issue diagnosis, and better performance insights across multi-device deployments.
Monthly summary for 2025-08 covering tt-mlir repo work. Delivered key feature testing and distributed profiling fixes that enhance reliability, performance instrumentation, and support for multi-device deployments. Key features delivered: - Semaphore Operation Testing and Cleanup: Implemented lit tests for semaphore semantics in the ttir->ttkernel path, refactored semaphore_set to remove an unused increment flavor, and added comprehensive tests for local set, remote increment, multicast set, and wait operations with/without reset (commit a80f5320cf5f8b355e7aee6dd83e3d53ecac4dc0). Major bugs fixed: - Distributed Profiling Stabilization for Multi-Device / MeshDevice: Refactored the profiling mechanism to correctly handle multi-device runtime IDs; separated host metadata population from results gathering; ensured program IDs are populated for multi-device programs, restoring and improving profiling functionality in a distributed environment (commit 291334c01d880402fd13a61e7628179862d6682f). Overall impact and accomplishments: - Improved test coverage and reliability for semaphore operations. - Restored and improved profiling accuracy and stability across distributed multi-device configurations, enabling better performance analysis and faster debugging. Technologies/skills demonstrated: - Lit-based testing for low-level synchronization primitives; test-driven development. - Code refactoring (semaphore_set cleanup) and test integration. - Distributed profiling instrumentation, multi-device runtime IDs, host metadata separation, and program ID population. - Strong focus on business value: higher confidence in correctness, faster issue diagnosis, and better performance insights across multi-device deployments.
July 2025: Delivered a targeted dependency update in tenstorrent/tt-metal to align Tracy with the latest state, enhancing stability and compatibility. No other features or bugs documented for this period.
July 2025: Delivered a targeted dependency update in tenstorrent/tt-metal to align Tracy with the latest state, enhancing stability and compatibility. No other features or bugs documented for this period.
June 2025: Summary focusing on business value and technical achievements for tenstorrent/tt-mlir. Work across the TTIR/TTKernel path emphasized code simplification, safer datamovement, and enabling larger tensor workloads. Key issues fixed improved reliability and performance, while new APIs and architecture refinements lay groundwork for multicast and multicore execution.
June 2025: Summary focusing on business value and technical achievements for tenstorrent/tt-mlir. Work across the TTIR/TTKernel path emphasized code simplification, safer datamovement, and enabling larger tensor workloads. Key issues fixed improved reliability and performance, while new APIs and architecture refinements lay groundwork for multicast and multicore execution.
May 2025 monthly summary for tenstorrent/tt-mlir focusing on D2M backend improvements, correctness, and maintainability. The month delivered several key backend enhancements, semaphore integration, and tiling optimizations, along with clearer ownership to streamline future work. These efforts collectively improve performance, reliability, and developer velocity for the D2M path and TTKernel-related conversions.
May 2025 monthly summary for tenstorrent/tt-mlir focusing on D2M backend improvements, correctness, and maintainability. The month delivered several key backend enhancements, semaphore integration, and tiling optimizations, along with clearer ownership to streamline future work. These efforts collectively improve performance, reliability, and developer velocity for the D2M path and TTKernel-related conversions.
April 2025 — Key features delivered: TTIR Lowering Pipeline Enhancements enabling TTIR → TTMetal/TTKernel translation with a new lowering scheme, using rewrites for memory allocation and generic operations, and activating D2M lowering along with new conversion patterns for alloc and generic ops. Commits: 83973437a459144b617dcb1e7647c5d1ea0a42c5; a3964526d40cd12b200f3f9244d48c54ab0866c9. Major bugs fixed: none documented for this repo this month. Overall impact and accomplishments: establishes an end-to-end TTIR translation path to target dialects, improving backend portability and maintainability, and setting the groundwork for future performance-oriented backends. Technologies/skills demonstrated: MLIR-based lowering, TTIR/TTMetal/TTKernel dialects, D2M lowering, rewrite-based memory/generic op handling, and operation-conversion patterns.
April 2025 — Key features delivered: TTIR Lowering Pipeline Enhancements enabling TTIR → TTMetal/TTKernel translation with a new lowering scheme, using rewrites for memory allocation and generic operations, and activating D2M lowering along with new conversion patterns for alloc and generic ops. Commits: 83973437a459144b617dcb1e7647c5d1ea0a42c5; a3964526d40cd12b200f3f9244d48c54ab0866c9. Major bugs fixed: none documented for this repo this month. Overall impact and accomplishments: establishes an end-to-end TTIR translation path to target dialects, improving backend portability and maintainability, and setting the groundwork for future performance-oriented backends. Technologies/skills demonstrated: MLIR-based lowering, TTIR/TTMetal/TTKernel dialects, D2M lowering, rewrite-based memory/generic op handling, and operation-conversion patterns.
March 2025 performance summary for tenstorrent/tt-mlir: Delivered a new TTIR tensor layout optimization pass that analyzes, selects, and enforces optimal tensor layouts to improve data handling and performance. The TTIROptimizeTensorLayout pass modifies generic operations and return operations to consistently apply chosen layouts and inserts necessary conversions. This work, landed under the commit D2M Pass 4: Tensor Layout (#2205) (992cf1b82fe5f389ab7bd455cf0d66b1753b8508), contributes to higher throughput and reduced layout-related overhead across downstream codegen and execution. No major bugs fixed this month; focus was on feature delivery and groundwork for broader rollout. Technologies demonstrated include MLIR TTIR dialect engineering, compiler passes, op rewriting, and conversion insertion.
March 2025 performance summary for tenstorrent/tt-mlir: Delivered a new TTIR tensor layout optimization pass that analyzes, selects, and enforces optimal tensor layouts to improve data handling and performance. The TTIROptimizeTensorLayout pass modifies generic operations and return operations to consistently apply chosen layouts and inserts necessary conversions. This work, landed under the commit D2M Pass 4: Tensor Layout (#2205) (992cf1b82fe5f389ab7bd455cf0d66b1753b8508), contributes to higher throughput and reduced layout-related overhead across downstream codegen and execution. No major bugs fixed this month; focus was on feature delivery and groundwork for broader rollout. Technologies demonstrated include MLIR TTIR dialect engineering, compiler passes, op rewriting, and conversion insertion.
February 2025: Delivered foundational TTIR enhancements in tenstorrent/tt-mlir, introducing generalized region operations with tile-based memory layout support. Implemented TTIR_GenericParent to enforce correct nesting within generic regions, and added tile_tilize_block and tile_untilize_block for converting between row-major and tiled layouts. Added a robust set of TTIR region operations (arithmetic, transcendental, reductions) and a specialized block matrix-multiplication op, accompanied by verifiers ensuring input/output element types. These changes enhance dialect expressiveness, correctness, and performance potential for downstream codegen.
February 2025: Delivered foundational TTIR enhancements in tenstorrent/tt-mlir, introducing generalized region operations with tile-based memory layout support. Implemented TTIR_GenericParent to enforce correct nesting within generic regions, and added tile_tilize_block and tile_untilize_block for converting between row-major and tiled layouts. Added a robust set of TTIR region operations (arithmetic, transcendental, reductions) and a specialized block matrix-multiplication op, accompanied by verifiers ensuring input/output element types. These changes enhance dialect expressiveness, correctness, and performance potential for downstream codegen.
January 2025 monthly summary for tenstorrent/tt-metal focusing on documentation improvements to support the Sweep framework. Delivered targeted README updates to clarify usage instructions and troubleshooting steps for querying test vectors and results, improving developer onboarding and operational efficiency.
January 2025 monthly summary for tenstorrent/tt-metal focusing on documentation improvements to support the Sweep framework. Delivered targeted README updates to clarify usage instructions and troubleshooting steps for querying test vectors and results, improving developer onboarding and operational efficiency.
November 2024 monthly summary focusing on delivering scalable data distribution capabilities in the TTKernel dialect and maintaining MLIR-based NoC integration for Tensix.
November 2024 monthly summary focusing on delivering scalable data distribution capabilities in the TTKernel dialect and maintaining MLIR-based NoC integration for Tensix.
October 2024 — tt-metal: Focused on strengthening test framework reliability and readability. Delivered consolidated test framework improvements across test vector generation and error handling; fixed a mis-import for PROFILER_LOGS_DIR in sweep framework tests; removed unused imports to clean up test code and improve readability. These changes enhance CI stability, reduce diagnostic effort, and improve maintainability of the test suite, directly contributing to faster feedback for profiler-enabled workflows and higher confidence in test results.
October 2024 — tt-metal: Focused on strengthening test framework reliability and readability. Delivered consolidated test framework improvements across test vector generation and error handling; fixed a mis-import for PROFILER_LOGS_DIR in sweep framework tests; removed unused imports to clean up test code and improve readability. These changes enhance CI stability, reduce diagnostic effort, and improve maintainability of the test suite, directly contributing to faster feedback for profiler-enabled workflows and higher confidence in test results.

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