#! /bin/sh -e

if [ $# -eq 3 -a "$2" = '-d' ]; then
    pdir="-d $3"
elif [ $# -ne 1 ]; then
    echo >&2 "`basename $0`: script expects -patch|-unpatch as argument"
    exit 1
fi
case "$1" in
    -patch) patch $pdir -f --no-backup-if-mismatch -p0 < $0;;
    -unpatch) patch $pdir -f --no-backup-if-mismatch -R -p0 < $0;;
    *)
	echo >&2 "`basename $0`: script expects -patch|-unpatch as argument"
	exit 1
esac
exit 0

# DP: From: David Huggins-Daines <dhuggins@linuxcare.com>
Sender: <dhd@thepuffingroup.com>
# DP: To: 55263@bugs.debian.org
# DP: Subject: Bug#55263: [PATCH] fixed in 2.96 CVS, here's a backport of the diff
# DP: Date: Wed, 01 Mar 2000 19:28:03 -0500

Hi,

# DP: I've found the minimal set of optimization flags that will produce
# DP: this error (the -O is necessary):
# DP: 
# DP: [dhd@doppelbock]:~/src/debian/ncurses4.2-4.2/obj_s$ cc -I../ncurses -I.  -DNDEBUG -I. -I../include -DHAVE_CONFIG_H -DTERMINFO=\"/usr/share/terminfo\" -O  -fcse-skip-blocks -fexpensive-optimizations -frerun-cse-after-loop -frerun-loop-opt -D_REENTRANT -fPIC -c ../ncurses/softscroll.c
# DP: ../ncurses/softscroll.c: In function `_nc_perform_scroll':
# DP: ../ncurses/softscroll.c:257: internal error--unrecognizable insn:
# DP: 
# DP: (insn 1213 1212 1215 (set (reg/v:DI 531)
# DP:         (mem/f:DI (symbol_ref:DI ("SP")) 0)) -1 (nil)
# DP:     (nil))
# DP: 
# DP: However, it seems that the bug is fixed in 2.96 from current CVS.
# DP: Here is the diff from 2.95.2 to 2.96 that solves the problem (I've
# DP: tested it, it seems to work):

--- gcc/emit-rtl.c.2.95.2	Wed Mar  1 18:19:18 2000
+++ gcc/emit-rtl.c	Wed Mar  1 18:23:29 2000
@@ -1856,25 +1728,17 @@
       return x;
 
     case MEM:
-      /* A MEM is allowed to be shared if its address is constant
-	 or is a constant plus one of the special registers.  */
-      if (CONSTANT_ADDRESS_P (XEXP (x, 0))
-	  || XEXP (x, 0) == virtual_stack_vars_rtx
-	  || XEXP (x, 0) == virtual_incoming_args_rtx)
+      /* A MEM is allowed to be shared if its address is constant.
+
+	 We used to allow sharing of MEMs which referenced 
+	 virtual_stack_vars_rtx or virtual_incoming_args_rtx, but
+	 that can lose.  instantiate_virtual_regs will not unshare
+	 the MEMs, and combine may change the structure of the address
+	 because it looks safe and profitable in one context, but
+	 in some other context it creates unrecognizable RTL.  */
+      if (CONSTANT_ADDRESS_P (XEXP (x, 0)))
 	return x;
 
-      if (GET_CODE (XEXP (x, 0)) == PLUS
-	  && (XEXP (XEXP (x, 0), 0) == virtual_stack_vars_rtx
-	      || XEXP (XEXP (x, 0), 0) == virtual_incoming_args_rtx)
-	  && CONSTANT_ADDRESS_P (XEXP (XEXP (x, 0), 1)))
-	{
-	  /* This MEM can appear in more than one place,
-	     but its address better not be shared with anything else.  */
-	  if (! x->used)
-	    XEXP (x, 0) = copy_rtx_if_shared (XEXP (x, 0));
-	  x->used = 1;
-	  return x;
-	}
       break;
 
     default:



-- 
David Huggins-Daines, Senior Linux Consultant, Linuxcare, Inc.
613.562.1239 tel
dhuggins@linuxcare.com, http://www.linuxcare.com/
Linuxcare. Support for the revolution.