Extend attribute deduction to determine whether parameters using indirect pass mode might have their address captured. Similarly to the deduction of `readonly` attribute this information facilitates memcpy optimizations.
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.