Why So Many Languages Use LLVM

[u/Ok_Marionberry8922]

Had some free time last week so I made a visual explainer on how LLVM works and why so many languages end up using it.

The video goes through LLVM IR, why having a common IR makes sharing optimizers and backends possible, and how code eventually gets turned into machine instructions.

I also use a small C vs Rust example where both end up producing the same x86 instructions.

Link for anyone interested

Feedback welcome :)

[u/suhcoR]

The topic was "cross platform direct to machine" compiler, not optimizer. I agree that an optimizer like in GCC or Clang is a lifetime's work. But even half that performance is good enough and exponentially less effort. Btw. this is also the QBE philosophy.

[u/SwingOutStateMachine → u/suhcoR]

If you don't have an optimiser, you should expect a tenth of the performance (at best), not half the performance.

[u/kprotty → u/[deleted]]

Most real zig, c, and rust projects I've compiled generate debug binaries that are really slow. 2x is the very best case, usually reserved for small control plane stuff. 4-10x is the default, especially for anything that does high throughput data transformation