void* __get_return_address(unsigned int level);
This intrinsic yields the return address of the current function. The level argument must be a constant value. A value of 0 yields the return address of the current function. Any other value yields a zero return address. On Linux systems, this intrinsic is synonymous with __builtin_return_address. The name and the argument are provided for compatibility with gcc*.
void __set_return_address(void* addr);
This intrinsic overwrites the default return address of the current function with the address indicated by its argument. On return from the current invocation, program execution continues at the address provided.
void* __get_frame_address(unsigned int level);
This intrinsic returns the frame address of the current function. The level argument must be a constant value. A value of 0 yields the frame address of the current function. Any other value yields a zero return value. On Linux systems, this intrinsic is synonymous with __builtin_frame_address. The name and the argument are provided for compatibility with gcc.