[backend] Add register allocation

Bug: 295189858
Test: mm and berberis_host_tests
Change-Id: Iae5d53c45fad76fc0dbd3e93e50fd1de4c2e717d
Merged-In: Iae5d53c45fad76fc0dbd3e93e50fd1de4c2e717d
4 files changed