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I don't know enough about why LLVM doesn't use parallel compilation, you might be right there. But there are many C++ compiler codebases that do have it, such
by azakai 4y ago
I don't know enough about why LLVM doesn't use parallel compilation, you might be right there.
But there are many C++ compiler codebases that do have it, such as: every major JS/Wasm VM (V8, SpiderMonkey, JSC), Binaryen, etc. Those do run in environments where parallel compilation matters a lot, unlike LLVM (which assumes parallelism in the build system, as you compile to object files).
- sanxiyn 4y agoRust wants parallel LLVM, because Rust has larger compilation unit.
- azakai 4y agoInteresting. That might be very specific to Rust, though. In that case, LLVM might not be the optimal backend for rustc. But this isn't an issue for most LLVM languages, which either assume parallelism in the build system, or they get enough benefit from ThinLTO (which is the parallelism LLVM does support at the link stage).