Tracking down a 25% Regression on LLVM RISC-V

Article

• Author traces 25% performance regression in LLVM’s RISC-V backend
• Bisects to a specific instruction scheduling change affecting loop code
• Fix restores performance by correcting register pressure heuristics
• Detailed walkthrough of compiler debugging methodology

Discussion

• Commenters appreciate seeing RISC-V ecosystem maturing at software level
• Suggestion raised: hook benchmarks to AI for automated regression detection
• One commenter notes this kind of compiler work shouldn’t be unpaid open-source labor
• Short thread; mostly appreciation for the detailed compiler debugging writeup

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