dwarf2out POST_insns patch

[Andrew Macleod <amacleod at cygnus dot com>]

The stormy16 port doesn't have any PRE_INC, PRE_DEC or PRE_MODIFY insns,
it only has the POST_ variations. When generating dwarf2 frame
information, we miss generating the DW_CFA_GNU_args_size opcode whenever
there is a stack push or pop for parameters. (and also a DW_CFA_def_cfa_offset
if the CFA is being tracked with SP.)

This patch modifies stack_adjust_offset to recognize either PRE_ or POST_
insns. Since this routine is only called on non-frame related instruction,
we aren't worried about where or what we are saving, only what the
stack adjustment is during the instruction. That lets us treat 
PRE_ and POST_ the same within this function.

This has been built and bootstrapped on x86 (for what thats worth) and verified 
to fix the problem on a stormy16 port.

Is this OK to check into mainline?

Andrew


	* dwarf2out.c (stack_adjust_offset): Add support for POST_INC, POST_DEC,
	and POST_MODIFY.

Index: gcc/dwarf2out.c
===================================================================
RCS file: /cvs/cvsfiles/devo/gcc/dwarf2out.c,v
retrieving revision 1.170
diff -c -p -r1.170 dwarf2out.c
*** gcc/dwarf2out.c	2001/10/22 08:35:00	1.170
--- gcc/dwarf2out.c	2002/02/25 17:41:08
*************** stack_adjust_offset (pattern)
*** 900,933 ****
  	return 0;
  
        offset = INTVAL (XEXP (src, 1));
      }
    else if (GET_CODE (dest) == MEM)
      {
        /* (set (mem (pre_dec (reg sp))) (foo)) */
        src = XEXP (dest, 0);
        code = GET_CODE (src);
  
!       if (! (code == PRE_DEC || code == PRE_INC
! 	     || code == PRE_MODIFY)
! 	  || XEXP (src, 0) != stack_pointer_rtx)
! 	return 0;
  
!       if (code == PRE_MODIFY)
! 	{
! 	  rtx val = XEXP (XEXP (src, 1), 1);
! 	  /* We handle only adjustments by constant amount.  */
! 	  if (GET_CODE (XEXP (src, 1)) != PLUS ||
! 	      GET_CODE (val) != CONST_INT)
! 	    abort();
! 	  offset = -INTVAL (val);
  	}
-       else offset = GET_MODE_SIZE (GET_MODE (dest));
      }
    else
      return 0;
- 
-   if (code == PLUS || code == PRE_INC)
-     offset = -offset;
  
    return offset;
  }
--- 900,953 ----
  	return 0;
  
        offset = INTVAL (XEXP (src, 1));
+       if (code == PLUS)
+ 	offset = -offset;
      }
    else if (GET_CODE (dest) == MEM)
      {
        /* (set (mem (pre_dec (reg sp))) (foo)) */
        src = XEXP (dest, 0);
        code = GET_CODE (src);
+       switch (code) 
+         {
+ 	case PRE_MODIFY:
+ 	case POST_MODIFY:
+ 	  if (XEXP (src, 0) == stack_pointer_rtx)
+ 	    {
+ 	      rtx val = XEXP (XEXP (src, 1), 1);
+ 	      /* We handle only adjustments by constant amount.  */
+ 	      if (GET_CODE (XEXP (src, 1)) != PLUS ||
+ 		  GET_CODE (val) != CONST_INT)
+ 		abort();
+ 	      offset = -INTVAL (val);
+ 	      break;
+ 	    }
+ 	  return 0;
  
! 	case PRE_DEC:
! 	case POST_DEC:
! 	  if (XEXP (src, 0) == stack_pointer_rtx)
! 	    {
! 	      offset = GET_MODE_SIZE (GET_MODE (dest));
! 	      break;
! 	    }
! 	  return 0;
  
! 	case PRE_INC:
! 	case POST_INC:
! 	  if (XEXP (src, 0) == stack_pointer_rtx)
! 	    {
! 	      offset = -GET_MODE_SIZE (GET_MODE (dest));
! 	      break;
! 	    }
! 	  return 0;
! 
! 	default:
! 	  return 0;
  	}
      }
    else
      return 0;
  
    return offset;
  }