GDB has support for figuring out that the target is doing a
longjmp and for stopping at the target of the jump, if we are
stepping. This is done with a few specialized internal breakpoints,
which are visible in the maint info breakpoint command.
To make this work, you need to define a macro called
GET_LONGJMP_TARGET, which will examine the jmp_buf
structure and extract the longjmp target address. Since jmp_buf
is target specific, you will need to define it in the appropriate
`tm-xxx.h' file. Look in `tm-sun4os4.h' and
`sparc-tdep.c' for examples of how to do this.