re PR bootstrap/41345 (bootstrap comparison failure with --disable-checking)

	PR bootstrap/41345
	* cfgcleanup.c (trivially_empty_bb_p): New function.
	(try_optimize_bb): Use it instead of checking BB_HEAD == BB_END.

	* gcc.dg/pr41345.c: New test.

From-SVN: r153569

gcc/ChangeLog

 2009-10-26  Jakub Jelinek  <jakub@redhat.com>
 
+	PR bootstrap/41345
+	* cfgcleanup.c (trivially_empty_bb_p): New function.
+	(try_optimize_bb): Use it instead of checking BB_HEAD == BB_END.
+
 	PR debug/41828
 	* dwarf2out.c (add_pubname, add_pubtype, generic_parameter_die,
 	add_name_and_src_coords_attributes, gen_namespace_die,

gcc/cfgcleanup.c

@@ -958,7 +958,7 @@ old_insns_match_p (int mode ATTRIBUTE_UNUSED, rtx i1, rtx i2)
   if (NOTE_INSN_BASIC_BLOCK_P (i1) && NOTE_INSN_BASIC_BLOCK_P (i2))
     return true;
 
-   p1 = PATTERN (i1);
+  p1 = PATTERN (i1);
   p2 = PATTERN (i2);
 
   if (GET_CODE (p1) != GET_CODE (p2))
@@ -1814,6 +1814,24 @@ try_crossjump_bb (int mode, basic_block bb)
   return changed;
 }
 
+/* Return true if BB contains just bb note, or bb note followed
+   by only DEBUG_INSNs.  */
+
+static bool
+trivially_empty_bb_p (basic_block bb)
+{
+  rtx insn = BB_END (bb);
+
+  while (1)
+    {
+      if (insn == BB_HEAD (bb))
+	return true;
+      if (!DEBUG_INSN_P (insn))
+	return false;
+      insn = PREV_INSN (insn);
+    }
+}
+
 /* Do simple CFG optimizations - basic block merging, simplifying of jump
    instructions etc.  Return nonzero if changes were made.  */
 
@@ -1865,14 +1883,10 @@ try_optimize_cfg (int mode)
 		 __builtin_unreachable ().  */
 	      if (EDGE_COUNT (b->preds) == 0
 		  || (EDGE_COUNT (b->succs) == 0
-		      && BB_HEAD (b) == BB_END (b)
+		      && trivially_empty_bb_p (b)
 		      && single_succ_edge (ENTRY_BLOCK_PTR)->dest != b))
 		{
 		  c = b->prev_bb;
-		  if (dump_file)
-		    fprintf (dump_file, "Deleting block %i.\n",
-			     b->index);
-
 		  delete_basic_block (b);
 		  if (!(mode & CLEANUP_CFGLAYOUT))
 		    changed = true;

gcc/testsuite/ChangeLog

 2009-10-26  Jakub Jelinek  <jakub@redhat.com>
 
+	PR bootstrap/41345
+	* gcc.dg/pr41345.c: New test.
+
 	PR debug/41828
 	* g++.dg/debug/dwarf2/anonname1.C: New test.
 

gcc/testsuite/gcc.dg/pr41345.c

+/* PR bootstrap/41345 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -g -fcompare-debug" } */
+
+void
+foo (int *x)
+{
+  int a;
+  for (a = 0; a < 2; a++)
+    if (x[a])
+      goto lab;
+  __builtin_unreachable ();
+lab:;
+}