C ++ SPARC总线错误 [英] C++ Bus error in SPARC arcitecture

问题描述

我想了解为什么我使用此代码遇到总线错误。

I would like to understand why I am getting a bus error with this code.

int main()
{
int p=34;
int *pp= (int *) ((char *)&p+1);
cout<<*pp<<"\n";
return 0;
}

推荐答案

对齐问题。在许多架构上，某些类型必须正确对齐，例如，4字节整数必须在4字节边界上开始。

It will no doubt be an alignment issue. On many architectures, certain types have to be aligned properly, an example being that 4-byte integers must start on a 4-byte boundary.

如果你访问非对齐的数据，一些架构不在乎，其他的会运行得更慢，其他人（如在这种情况下）将落在一个尖叫的堆。

If you access non-aligned data, some architectures won't care, others will run slower, still others (such as in this case) will fall in a screaming heap.

当您创建 整数 p 时，它将在堆栈上正确对齐的地址是正确的倍数。

When you create the integer p, it will be aligned correctly on the stack at an address which is a correct multiple.

通过在字节上移动该地址，并解除引用 int ，您会导致 SIGBUS 。

By moving that address up on byte, and de-referencing that as an int, you're causing the SIGBUS.

Oracle上的此链接显示对齐要求。简而言之：

This link at Oracle shows the alignment requirements. In short:

• 整数在16位边界上对齐。




• 长整型在64位边界上对齐。


• 长整数在64位边界上对齐。

• short integers are aligned on 16-bit boundaries.
• int integers are aligned on 32-bit boundaries.
• long integers are aligned on 64-bit boundaries for SPARC systems.
• long long integers are aligned on 64-bit boundaries.

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