Module src.backend.backend

"""
Serves as the main interface to the backend of the compiler. Performs instruction generation and register allocation.
"""

from inspect import getsourcefile
from importlib.machinery import SourceFileLoader
import os

asmn = SourceFileLoader("ASMNode", f"{os.path.dirname(os.path.abspath(getsourcefile(lambda:0)))}/ASMNode.py").load_module()
ir1 = SourceFileLoader("IR_Lv1_Builder", f"{os.path.dirname(os.path.abspath(getsourcefile(lambda:0)))}/../optimizer/IR_Lv1_Builder.py").load_module()
alloc = SourceFileLoader("allocator", f"{os.path.dirname(os.path.abspath(getsourcefile(lambda:0)))}/../backend/allocator.py").load_module()


def main(args, IR):
    """
    The main backend function, does register allocation and converts a given IR to assembly

    Args:
        args: The command line arguments of the operation (print asm, etc.)
        IR: The intermediary representation in a list of IRNode objects that is being converted to assembly
    """
    # List of assembly instructions before given allocated registers
    asm = [z for x in IR.IR for y in x.treeList for z in y.asm()]

    # Allocate registers for assembly instructions
    allocator = alloc.Allocator
    asm = allocator.allocateRegisters(asm)

    asm = [
        asmn.ASMNode(None, None, None, boilerPlate=f".file \"{args.input_file.split('/')[-1]}\""),
        asmn.ASMNode( None, None,None, boilerPlate=f".text"),
    ] + asm

    # Output assembly to stdout
    if args.asm:
        for i in asm:
            print(str(i))

    # Output assembly to a file
    if args.ASMout:
        write_assembly_to_file(args.ASMout, asm)


def write_assembly_to_file(filename, asm):
    """
    Outputs assembly to the given file

    Args:
        filename: The given file to write to
        asm: List of assembly Nodes each containing an instruction
    """
    with open(filename, 'w') as f:
        for assemblyLine in asm:
            f.write(str(assemblyLine) + '\n')


if __name__ =="__main__":
    main()