The whole LLVM toolchain is a bit big. I think we can reduce much more the size. We actually researched on using tcc but unfortunately tcc doesn’t have a wasm backend (for generating wasm output). It would be awesome if they added it!
Cranelift is a fast, secure, relatively simple and innovative compiler backend. It takes an intermediate representation of a program generated by some frontend and compiles it to executable machine code. Cranelift is meant to be used as a library within an "embedder".
It is in successful use by the Wasmtime WebAssembly virtual machine, for just-in-time (JIT) and ahead-of-time (AOT) compilation, and also as an experimental backend for the Rust compiler.
Cranelift is an optimizing compiler, but it aims to take a fresh look at which optimizations are necessary. We have explicitly avoided features -- such as advanced alias analysis or use of undefined behavior -- that have historically led to subtle miscompilations in other compilers. Cranelift consists of about 200 thousand lines of code; in contrast, e.g. LLVM consists of over 20 million lines of code, a hundred times larger. This difference also allows Cranelift to be relatively approachable to developers, researchers, auditors and others who wish to understand how it works.