Comment by Joker_vD

Yes, you can dump your IR straight to the disk and then stream it to process further. That's how quite a number of compilers (and assemblers) were written back in the 70s and it was quite painful.

IIRC, Unix's original as works that way: during assembly, the text and data sections are written into separate temporary files, and then they are merged together into the a.out. And yes, it's slow.