The compiler gods have added the llvm-mos C compiler to the Compiler Explorer at godbolt.org.
This means that you can experiment with llvm-mos 6502 codegen without installing anything locally.
Here's an example of llvm-mos running a compile-time calculation in C:
https://godbolt.org/z/5xer5nYsEAnd here's an example of code running on an emulated NES (click on the popup in the lower right corner to watch the emulation run):
https://godbolt.org/z/MxaoKvEfsMore info about llvm-mos is available at
https://www.llvm-mos.org.