There&#x27;s still an implicit question there, concerning why one would choose to develop a new IR rather than enhancing LLVM (the latter of which the Rust devs (and <i>especially</i> the Swift devs) have had years of experience doing). Though I&#x27;m not trying to suggest that Rust made the wrong decision or is suffering from NIH, because MIR is great, and there&#x27;s no reason to suspect that shoving absolutely everything down into LLVM is necessarily a tractable solution. I&#x27;m just curious which Rust-specific and Swift-specific optimizations these IRs enable above and beyond LLVM IR&#x27;s capabilities, and what that says about each source language in turn (especially if we regard LLVM IR as a proxy for C, being LLVM&#x27;s original target).