re PR debug/46782 (-fcompare-debug failure (length) with -fvar-tracking)

gcc/ChangeLog:
PR debug/46782
* cfgcleanup.c (try_forward_edges): Skip debug insns.
gcc/testsuite/ChangeLog:
PR debug/46782
* gcc.dg/debug/pr46782.c: New.

From-SVN: r167737

gcc/ChangeLog

+2010-12-13  Alexandre Oliva  <aoliva@redhat.com>
+
+	PR debug/46782
+	* cfgcleanup.c (try_forward_edges): Skip debug insns.
+
 2010-12-12  Jan Hubicka  <jh@suse.cz>
 	    Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 

gcc/cfgcleanup.c

@@ -487,11 +487,17 @@ try_forward_edges (int mode, basic_block b)
 		    new_target = NULL;
 		  else
 		    {
+		      rtx last;
+
 		      if (new_locus)
 			locus = new_locus;
 
-		      new_locus = INSN_P (BB_END (target))
-				  ? INSN_LOCATOR (BB_END (target)) : 0;
+		      last = BB_END (target);
+		      if (DEBUG_INSN_P (last))
+			last = prev_nondebug_insn (last);
+
+		      new_locus = last && INSN_P (last)
+				  ? INSN_LOCATOR (last) : 0;
 
 		      if (new_locus && locus && !locator_eq (new_locus, locus))
 			new_target = NULL;

gcc/testsuite/ChangeLog

+2010-12-13  Alexandre Oliva  <aoliva@redhat.com>
+
+	PR debug/46782
+	* gcc.dg/debug/pr46782.c: New.
+
 2010-12-12  Janus Weil  <janus@gcc.gnu.org>
 
 	PR fortran/46809

gcc/testsuite/gcc.dg/debug/pr46782.c

+/* PR debug/46782 */
+/* { dg-do compile } */
+/* { dg-options "-w -O0 -fvar-tracking -fcompare-debug" } */
+
+void foo (int i)
+{
+  if (i)
+    i++;
+  while (i)
+    ;
+}