should be spilled. Add a simple mechanic to stop possible infinite loop
in regalloc.

AH/BH/CH/DH

with RegGroup::get_from_value

still restored callee-saved registers, should directly jump to it

size, etc). add PRINTHEX instruction to print a number (for debugging use)

This reverts commit 54ce8e1c.

internally they do nothing (gc doesnt move in zebu atm)

replacing most uses of HashMap with LinkedHashMap. This will reduce (if not eliminate) undeterminism in the compilation.
Copied LinkedHashMap implementation to local so that I can implement encode/decode and other necessary methods

when we add interefence between %a and %edi, we also add %a with %rdi
because we cannot assign rdi to a