35f443d318
Use standard attribute logic for allocator shim Use llfn_attrs_from_instance() to generate the attributes for the allocator shim. This ensures that we generate all the usual attributes (and don't get to find out one-by-one that a certain attribute is important for a certain target). Additionally this will enable emitting the allocator-specific attributes (not included here). This change is quite awkward because the allocator shim uses SimpleCx, while llfn_attrs_from_instance uses CodegenCx. I've switched it to use SimpleCx plus tcx/sess arguments where necessary. If there's a simpler way to do this, I'd love to know about it...
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.