Compiling Rust to WebAssembly with debug info can be up to 40x slower due to an incomplete LLVM bug fix. The issue stems from DBG_VALUE records multiplying during heavy inlining and requiring excessive register-to-stack moves on WebAssembly's stack-machine architecture.
Background
LLVM has a known bug where DBG_VALUE debug info records are inefficiently handled during code generation, previously fixed for clang but not fully for WebAssembly targets.
- Source
- Lobsters
- Published
- Aug 20, 2026 at 08:32 PM
- Score
- 6.0 / 10