[PATCH/RFA] Allow register other than SP for DWARF2 CFA

Richard Henderson rth@redhat.com
Mon Jun 17 16:45:00 GMT 2002

On Mon, Jun 17, 2002 at 02:47:10PM -0700, Jason R Thorpe wrote:
> This implements Richard's suggestion in:
> 	http://gcc.gnu.org/ml/gcc/2002-06/msg00697.html
> ...needed to support DWARF2 on VAX.  I *think* all the remaining uses of
> STACK_POINTER_REGNUM in dwarf2out.c are okay, but I would appreciate a
> sanity-check on that.

Actually, thinking about this some more, I'm not absolutely sure this
is going to help you any.  You still need to get the SP restored during
the unwinding process.  How else except by it being the CFA regnum?

Naturally, since this is the VAX, there's not much to help me out in
the port itself.  I vaguely remember that just about everything happens
in hardware during the call insn itself.

Can you draw me some pictures of what the stack looks like

  (1) immediately before a call
  (2) at the function entry label
  (3) after any function prologue
  (4) after the function return

In particular, where are SP, FP, AP, and their saved slots.

We have to put enough information into the dwarf2 into to be able
to make the 3->4 transition.


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