使用TBLPTR时出错

我正在寻找一个bug，我怀疑XC8和我在一起。这个程序是一个引导加载程序，一旦我开始擦除闪存，更多的东西就开始崩溃。首先，Micro是PIC18F66 K80系列。这个问题一旦出现，下面的代码首先被执行。程序的基本描述是通过CANBUS接收消息，试图根据定义的格式将它们解析成一个命令，并处理这些命令，包括程序存储器的擦除/写入/验证。简化：当Prttf语句执行时，我可以使用调试器检查TBLPTR的值。当然，它指向“Bootloader仍然有效”的有效载荷的内存位置。然而，在执行第一存储器擦除块之后，下一个PRTTF写入垃圾。用调试器再次检查，TBLPTR仍然指向刚才擦除的内存。为什么编译器不保证它再次被正确地设置？



      以下为原文

    I'm hunting down a bug where I'm having suspicions against XC8 messing with me. The program in question is a bootloader, and once I start erasing flash memory, more things start to break down.
First, the micro is a PIC18F66K80 series. The problem exhibits once the code below is first executed.


    else if (blpLastLine.cmdType == BLP_EraseFlash) {
        response.dataLen = 0;
        response.isAck = true;

        // setup TABLPTR
        TBLPTRU = blpLastLine.address[2];
        TBLPTRH = blpLastLine.address[1];
        TBLPTRL = blpLastLine.address[0];
        
        // erase block
        EECON1bits.EEPGD = 1; // point to Flash program memory
        EECON1bits.CFGS = 0; // access Flash program memory
        EECON1bits.WREN = 1;
        EECON1bits.FREE = 1;
        EECON2 = 0x55;
        EECON2 = 0xAA;
        EECON1bits.WR = 1; // erase block
        
        EECON1bits.FREE = 0;
        EECON1bits.WREN = 0;
        EECON1bits.EEPGD = 0;
    }
   

Basic description of the program is it receives messages over canbus, tries to parse them into a command according to a format I defined and handles those commands, which include erase/write/verify of program memory. Simplified:


while (true) {
  CanBuffer* b = canReceive();
  if (b != NULL) handleMsg(b);
  printf("bootloader still activen");
}


When the printf statement executes, I can inspect the value of TBLPTR using the debugger. Of course, it points to the memory location of the "bootloader still active" payload. However, after executing the first memory erase block, the next printf writes garbage. Inspecting again with the debugger, the TBLPTR still points to the memory we just erased. Why doesn't the compiler ensure it gets set properly again?