b2bc46938c
Previously we only exposed a kreg register class which excludes the k0 register since it can't be used in many instructions. However k0 is a valid register and we need to have a way of marking it as clobbered for clobber_abi. Fixes #94977
The codegen crate contains the code to convert from MIR into LLVM IR,
and then from LLVM IR into machine code. In general it contains code
that runs towards the end of the compilation process.
For more information about how codegen works, see the rustc dev guide.