[zozbot234]

> For example, the 6502 really wants to replace stack usage with global usage; we do this absolutely whenever possible.

If I understand what you're getting at, this transformation comes up all the time when compiling either coroutines or user-space "green" threads. More obviously, it could expand the usefulness of LLVM for targeting very low-end microcontrollers (even "modern" ones targeting varieties of ARM or other recent architectures) where stack space, and memory more generally is often at a premium.