…exactly like a source-file-error.
…1308 the eliminatable-copy? word is the fix. the previous code only checked that the registers had the same register class, but you also need to check that they dont have the same representation size. because a copy from double-rep -> double-2-rep is not eliminatable
initial leader-map and class-element-map
to see if an insn is peephole-optimizable + test
sync points in the cfg
because it's nicer if all instruction unions have the -insn suffix and the ## prefix is reserved for tuples