Unix Stack Frame Questions

[The Grey Wolf]

/* <GOEHRING.91Mar25113709 at gnu.ai.mit.edu> by goehring at gnu.ai.mit.edu
 * In article <125 at epic.epic.com> tan at epic.epic.com (Andy Tan) writes:
 * 
 *    1. Is it right to assume that the address of the last automatic
 *       variable is the bottom of stack frame ?
 * 
 * it is not right to assume that there is a stack frame, and some
 * compilers aren't going to put autos in the frame even if a frame
 * exists since they can be more cheaply handled with registers.

If, of course, you have the registers (68K only have so many).
If there's not a stack frame, how are parameters passed to the
function...?  And how would you return...?

 * every cpu is going to have varying stack frame format(s), assuming the
 * cpu enforces one at all, and OS and compiler vendors are more than happy
 * to create oddball parameter passing and stack frame conventions.

I didn't think that a CPU ever "enforced" a stack frame; ostensibly one
could ignore the references to "4(fp)" in the manual and do it their own
way.

But a stack frame seems to be the most efficient way of dealing with
calls and returns.

 * --
 * Help stamp out vi in our lifetime!
 * Scott Goehring			goehring at gnu.ai.mit.edu
 * On exile in Indianapolis, IN