Footnotes

(1)

The function cast is not portable ISO C.

(2)

As of this writing (April 2001), setting verbosity level is not yet implemented, and is always returned as zero. So calling ui_out_message with a verbosity argument more than zero will cause the message to never be printed.

(3)

Some D10V instructions are actually pairs of 16-bit sub-instructions. However, since you can't jump into the middle of such a pair, code addresses can only refer to full 32 bit instructions, which is what matters in this explanation.

(4)

Historically, GDB always had a concept of a frame pointer register, which could be accessed via the GDB variable, $fp. That concept is now deprecated, recognizing that not all architectures have a frame pointer. However if an architecture does have a frame pointer register, and defines a register or pseudo-register with the name "fp", then that register will be used as the value of the $fp variable.

(5)

This is a simplified example for illustrative purposes only. Good optimizing compilers would not put anything on the stack for such simple functions. Indeed they might eliminate the recursion and use of the stack entirely!

(6)

It is worth noting that if it cannot be determined in any other way (for example by there being a register with the name "fp"), then the result of the this_base function will be used as the value of the frame pointer variable $fp in GDB. This is very often not correct (for example with the OpenRISC 1000, this value is the stack pointer, $sp). In this case a register (raw or pseudo) with the name "fp" should be defined. It will be used in preference as the value of $fp.