[PATCH] output INCOMING_RETURN_ADDR_RTX in debug info

[Nathan Froyd <froydnj@codesourcery.com>]

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When PR 24444 was fixed, recording the initial location of the return
address in debug info was made dependent on whether DWARF2_UNWIND_INFO
was defined and was true at runtime.  On targets where
DWARF2_UNWIND_INFO is defined to 0, this was a change in behavior from
the previous method, which was to output the initial location of the
return address if DWARF2_UNWIND_INFO was simply defined.

The current behaviour is inconvenient for the debugger on platforms
where DWARF2_UNWIND_INFO is 0, but INCOMING_RETURN_ADDR_RTX is defined.
(Since the debugger now has to guess where the return address is,
whereas the compiler could have simply told it.)  On such platforms
(e.g. vxworks targets), we already record register saves in the prologue
in the debug info; we might as well record where the return address is
too.  The attached patch changes things to record the initial location
of the return address if INCOMING_RETURN_ADDR_RTX is defined.

I don't see a reason to make this information conditional on
DWARF2_UNWIND_INFO--but I am also not a debug info expert.
Clarifications/corrections welcome!

Bootstrapped and tested on i586-wrs-vxworks.  OK to commit?

:ADDPATCH dwarf2:

-Nathan

2007-08-03  Nathan Froyd  <froydnj@codesourcery.com>

	gcc/
	* dwarf2out.c (dwarf2out_frame_init): Make saving
	INCOMING_RETURN_ADDR_RTX dependent on whether it is defined.


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Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c	(revision 178052)
+++ gcc/dwarf2out.c	(working copy)
@@ -2612,9 +2612,8 @@ dwarf2out_frame_init (void)
   /* On entry, the Canonical Frame Address is at SP.  */
   dwarf2out_def_cfa (NULL, STACK_POINTER_REGNUM, INCOMING_FRAME_SP_OFFSET);
 
-#ifdef DWARF2_UNWIND_INFO
-  if (DWARF2_UNWIND_INFO)
-    initial_return_save (INCOMING_RETURN_ADDR_RTX);
+#ifdef INCOMING_RETURN_ADDR_RTX
+  initial_return_save (INCOMING_RETURN_ADDR_RTX);
 #endif
 }