gdb (gdborig) crash on some code in 64 bits

GDB (gdborig.exe) crash on some code. This problem only shows up when debug code for 64 bits.
To reproduce:

• use code below
• build by mingw 64 bits
• set breakpoint on "return 0;"
• debug.

Example code:

#include <stdio.h>

int main()
{
    {
        char    buf[256];
    }

    return 0;
}