请帮我实现一个完整的目标代码生成器

目标代码生成是编译过程中最后一个阶段，其主要任务是将中间代码转换为目标机器上可执行的机器码。下面是一个简单的目标代码生成器的实现示例：

class CodeGenerator:
    def __init__(self, ir):
        self.ir = ir
        self.code = []

    def generate_code(self):
        for instr in self.ir:
            opcode = instr[0]
            if opcode == 'LOAD':
                self.load(instr)
            elif opcode == 'ADD':
                self.add(instr)
            elif opcode == 'SUB':
                self.sub(instr)
            elif opcode == 'MUL':
                self.mul(instr)
            elif opcode == 'DIV':
                self.div(instr)
            elif opcode == 'MOV':
                self.mov(instr)
            elif opcode == 'JMP':
                self.jmp(instr)
            elif opcode == 'JZ':
                self.jz(instr)
            elif opcode == 'PRINT':
                self.print(instr)

    def load(self, instr):
        operand1, operand2, result = instr[1], instr[2], instr[3]
        self.code.append("MOV %s, [%s]" % (result, operand2))
        self.code.append("ADD %s, %s" % (result, operand1))

    def add(self, instr):
        operand1, operand2, result = instr[1], instr[2], instr[3]
        self.code.append("ADD %s, %s" % (result, operand1))
        self.code.append("ADD %s, %s" % (result, operand2))

    def sub(self, instr):
        operand1, operand2, result = instr[1], instr[2], instr[3]
        self.code.append("MOV %s, %s" % (result, operand1))
        self.code.append("SUB %s, %s" % (result, operand2))

    def mul(self, instr):
        operand1, operand2, result = instr[1], instr[2], instr[3]
        self.code.append("MOV %s, %s" % (result, operand1))
        self.code.append("MUL %s, %s" % (result, operand2))

    def div(self, instr):
        operand1, operand2, result = instr[1], instr[2], instr[3]
        self.code.append("MOV %s, %s" % (result, operand1))
        self.code.append("DIV %s, %s" % (result, operand2))

    def mov(self, instr):
        operand, result = instr[1], instr[2]
        self.code.append("MOV %s, %s" % (result, operand))

    def jmp(self, instr):
        label = instr[1]
        self.code.append("JMP %s" % label)

    def jz(self, instr):
        operand, label = instr[1], instr[2]
        self.code.append("CMP %s, 0" % operand)
        self.code.append("JZ %s" % label)

    def print(self, instr):
        operand = instr[1]
        self.code.append("PUSH %s" % operand)
        self.code.append("CALL print")

    def get_code(self):
        return self.code

以上是一个简单的目标代码生成器的实现示例，它支持以下中间代码指令：

- LOAD
- ADD
- SUB
- MUL
- DIV
- MOV
- JMP
- JZ
- PRINT

你可以根据你的具体需求对其进行修改和扩展。