August 2025 focused on enhancing the clarity and maintainability of the MGSC (Multi-Grain State Correlation) branch predictor in GEM5 for the OpenXiangShan project. The primary delivery was a parameter renaming effort to use descriptive names for table numbers, history lengths, and index widths, aligning with existing conventions and reducing ambiguity for future tuning and reviews. This work strengthens code readability and supports safer performance modeling as part of ongoing predictor improvements.

OpenXiangShan/XiangShan — April 2025: Focused on frontend memory subsystem optimization to reduce bottlenecks and improve throughput in Ftq. Delivered a targeted SRAM configuration tuning and a code-path fix that improves data handling and eliminates mis-identification of memory paths. These changes are backed by two commits for traceability and faster future tuning. Overall impact: improved frontend data path throughput, reduced risk of timing/path misclassification, and smoother Ftq SRAM operation, enabling more robust hardware builds and upcoming performance features.

Concise monthly summary for 2025-03 focused on delivering architecturally meaningful features, stabilizing core subsystems, and enabling future growth. Highlights include a Rocket-chip submodule upgrade with a fix to instruction decoding for c.addi when destination is x0, and a SRAM-centric refactor introducing a SplittedSRAM module to support scalable meta SRAM configurations.

February 2025: Fixed Jalr Prediction Taken logic in PreDecode for OpenXiangShan/XiangShan to improve branch prediction accuracy and overall reliability. Patch ensures correct detection of taken predictions for jalr, addressing reliability gaps flagged in #4269. Commit 7f475a241b2cdf869833f641138fdf66b32c9bd6.

January 2025 – OpenXiangShan/XiangShan: Focused improvements on the Instruction Fetch Unit (IFU) to strengthen correctness and control-flow reliability while reducing unnecessary flush activity. Delivered two targeted changes: (1) IFU flush optimization removing redundant BPU override flush logic to simplify flush signal generation and improve control flow, and (2) IFU misprediction handling for jalr by adding range checks to terminate instruction blocks on misprediction. These changes improve fetch-path correctness, reduce risk of executing incorrect instructions after mispredictions, and lower maintenance burden. Business value: more predictable performance, fewer corner-case bugs, and a cleaner, more maintainable IFU code path.

Concise monthly summary for 2024-11 highlighting delivered features, fixed issues, impact, and technologies demonstrated for OpenXiangShan/XiangShan. Focus on business value and technical achievements, with clear references to delivered commits.

Month 2024-10 summary focusing on expanding RISC-V Zcb ISA coverage and improving correctness across the XiangShan/OpenXiangShan stack. Delivered a targeted bug fix for illegal instruction checks related to zcb arithmetic in the Rocket-chip subproject, and added RISC-V Zcb extension support in NEMU by enabling the extension, introducing new Zcb arithmetic definitions, and updating the decoder and execution helpers. These changes enhance ISA compliance, reduce misinterpretation of Zcb instructions, and enable end-to-end emulation and testing of Zcb operations.