Asm报数组异常-如ArrayIndexOutOfBoundsException

java.lang.NegativeArraySizeException
	at org.springframework.asm.frame.merge(frame.java:1222)
	at org.springframework.asm.MethodWriter.computeAllframes(MethodWriter.java:1610)
	at org.springframework.asm.MethodWriter.visitMaxs(MethodWriter.java:1546)
	at com.nailsoul.spring.core.asm.proxy.asm.util.CodeUtils.endMethod(CodeUtils.java:273)

如发生在 if场景 IFGT之前没有往栈内压入int类型数据

CodeUtils.condition(mv,IFGT,()->{
	mv.visitVarInsn(ALOAD,2);
	mv.visitInsn(POP);
});

修复代码

mv.visitIntInsn(BIPUSH,3);
CodeUtils.condition(mv,IFGT,()->{
	mv.visitVarInsn(ALOAD,2);
	mv.visitInsn(POP);
});

数字不一定是0

java.lang.ArrayIndexOutOfBoundsException: 0

	at org.springframework.asm.frame.merge(frame.java:1268)
	at org.springframework.asm.frame.merge(frame.java:1244)
	at org.springframework.asm.MethodWriter.computeAllframes(MethodWriter.java:1610)
	at org.springframework.asm.MethodWriter.visitMaxs(MethodWriter.java:1546)
	at com.nailsoul.spring.core.asm.proxy.asm.util.CodeUtils.endMethod(CodeUtils.java:273)

通过asm动态添加方法时 时不时报数组越界错误 经过分析
分为生成的代码运行是逻辑异常 和 语法异常

• 逻辑异常
  空数组访问下标为0的元素肯定报错
  根据异常打印的调用链可以区分
• 语法异常
  把变量压入栈内 没处理到致的 如以下获取数组指定下标元素 通常visitMaxs引起的

  mv.visitVarInsn(ALOAD,2);
  mv.visitVarInsn(ILOAD,4);
  mv.visitInsn(AALOAD);
  

对应的代码

var2[var4];

后续没有处理 肯定得标红

修复

mv.visitVarInsn(ALOAD,2);
mv.visitVarInsn(ILOAD,4);
mv.visitInsn(AALOAD);
// 只要把该元素消费调就行 如pop
mv.visitVarInsn(ASTORE,5);

有时相同代码明明在这A处不报错 移到B处就报错了 如
没有被if等快包裹时 没问题

mv.visitLdcInsn(11);
mv.visitVarInsn(ILOAD,4);

被if包裹 就报错了

CodeUtils.condition(mv,IFGT,()->{
	mv.visitLdcInsn(11);
	mv.visitVarInsn(ILOAD,4);
});

修复代码

CodeUtils.condition(mv,IFGT,()->{
	mv.visitLdcInsn(11);
	mv.visitVarInsn(ILOAD,4);
	mv.visitInsn(POP2);
});