Python 代码优化 ➢要求能自动对输入的四元式进行基本块的划分，并对基本块内的代码利用DAG进行优化，生成优化后的四元式代码。

以下是一个简单的 Python 代码示例，演示了如何使用基本块划分和DAG优化算法对四元式进行优化： ```python # 定义四元式列表 quadruples = [ ("+", "a", "b", "t1"), ("*", "t1", "c", "t2"), ("-", "t2", "d", "t3"), ("=", "t3", "", "e"), ("if", "e", "", "L1"), ("+", "f", "g", "t4"), ("*", "t4", "h", "t5"), ("-", "t5", "i", "t6"), ("=", "t6", "", "j"), ("goto", "", "", "L2"), ("label", "", "", "L1"), ("print", "k", "", ""), ("label", "", "", "L2") ] # 划分基本块 basic_blocks = [] current_block = [] for quadruple in quadruples: current_block.append(quadruple) if quadruple[0] == "if" or quadruple[0] == "goto" or quadruple[0] == "label": basic_blocks.append(current_block) current_block = [] # 对每个基本块进行DAG优化 optimized_quadruples = [] for block in basic_blocks: dag = {} for quadruple in block: if quadruple[0] == "=": if quadruple[1] not in dag: dag[quadruple[1]] = {"op": "=", "arg1": quadruple[2], "arg2": None} else: dag[quadruple[1]]["arg1"] = quadruple[2] optimized_quadruples.append(quadruple) else: arg1 = dag[quadruple[1]] if quadruple[1] in dag else quadruple[1] arg2 = dag[quadruple[2]] if quadruple[2] in dag else quadruple[2] if (arg1, arg2) not in dag.values(): t = "t" + str(len(dag) + 1) dag[t] = {"op