cfgcleanup.c (try_forward_edges): Do not throw away previous steps when stopping because of a different locus on...

	* cfgcleanup.c (try_forward_edges): Do not throw away previous steps
	when stopping because of a different locus on edge or insn.
	(try_optimize_cfg): Add comment.
	* cfgrtl.c (rtl_merge_blocks): Tweak log message.  If the destination
	block is a forwarder block, propagate locus on the edge.
	(cfg_layout_merge_blocks): Likewise.

From-SVN: r165789

3 files changed, 48 insertions, 17 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 72be43d..b834082 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2010-10-21  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* cfgcleanup.c (try_forward_edges): Do not throw away previous steps
+	when stopping because of a different locus on edge or insn.
+	(try_optimize_cfg): Add comment.
+	* cfgrtl.c (rtl_merge_blocks): Tweak log message.  If the destination
+	block is a forwarder block, propagate locus on the edge.
+	(cfg_layout_merge_blocks): Likewise.
+
 2010-10-21  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/45946
diff --git a/gcc/cfgcleanup.c b/gcc/cfgcleanup.c
index 9563e3f..881a4f3 100644
--- a/gcc/cfgcleanup.c
+++ b/gcc/cfgcleanup.c
@@ -485,22 +485,28 @@ try_forward_edges (int mode, basic_block b)
 		{
 		  /* When not optimizing, ensure that edges or forwarder
 		     blocks with different locus are not optimized out.  */
-		  int locus = single_succ_edge (target)->goto_locus;
+		  int new_locus = single_succ_edge (target)->goto_locus;
+		  int locus = goto_locus;
 
-		  if (locus && goto_locus && !locator_eq (locus, goto_locus))
-		    counter = n_basic_blocks;
-		  else if (locus)
-		    goto_locus = locus;
-
-		  if (INSN_P (BB_END (target)))
+		  if (new_locus && locus && !locator_eq (new_locus, locus))
+		    new_target = NULL;
+		  else
 		    {
-		      locus = INSN_LOCATOR (BB_END (target));
+		      if (new_locus)
+			locus = new_locus;
 
-		      if (locus && goto_locus
-			  && !locator_eq (locus, goto_locus))
-			counter = n_basic_blocks;
-		      else if (locus)
-			goto_locus = locus;
+		      new_locus = INSN_P (BB_END (target))
+				  ? INSN_LOCATOR (BB_END (target)) : 0;
+
+		      if (new_locus && locus && !locator_eq (new_locus, locus))
+			new_target = NULL;
+		      else
+			{
+			  if (new_locus)
+			    locus = new_locus;
+
+			  goto_locus = locus;
+			}
 		    }
 		}
 	    }
@@ -2379,6 +2385,7 @@ try_optimize_cfg (int mode)
 		  continue;
 		}
 
+	      /* Merge B with its single successor, if any.  */
 	      if (single_succ_p (b)
 		  && (s = single_succ_edge (b))
 		  && !(s->flags & EDGE_COMPLEX)
diff --git a/gcc/cfgrtl.c b/gcc/cfgrtl.c
index a158112..a19ba8d 100644
--- a/gcc/cfgrtl.c
+++ b/gcc/cfgrtl.c
@@ -588,10 +588,12 @@ rtl_merge_blocks (basic_block a, basic_block b)
   rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
   rtx del_first = NULL_RTX, del_last = NULL_RTX;
   rtx b_debug_start = b_end, b_debug_end = b_end;
+  bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0;
   int b_empty = 0;
 
   if (dump_file)
-    fprintf (dump_file, "merging block %d into block %d\n", b->index, a->index);
+    fprintf (dump_file, "Merging block %d into block %d...\n", b->index,
+	     a->index);
 
   while (DEBUG_INSN_P (b_end))
     b_end = PREV_INSN (b_debug_start = b_end);
@@ -680,6 +682,13 @@ rtl_merge_blocks (basic_block a, basic_block b)
 
   df_bb_delete (b->index);
   BB_END (a) = a_end;
+
+  /* If B was a forwarder block, propagate the locus on the edge.  */
+  if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus)
+    EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus;
+
+  if (dump_file)
+    fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index);
 }
 
 
@@ -2692,10 +2701,13 @@ cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
 static void
 cfg_layout_merge_blocks (basic_block a, basic_block b)
 {
+  bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0;
+
   gcc_checking_assert (cfg_layout_can_merge_blocks_p (a, b));
 
   if (dump_file)
-    fprintf (dump_file, "merging block %d into block %d\n", b->index, a->index);
+    fprintf (dump_file, "Merging block %d into block %d...\n", b->index,
+			 a->index);
 
   /* If there was a CODE_LABEL beginning B, delete it.  */
   if (LABEL_P (BB_HEAD (b)))
@@ -2803,9 +2815,12 @@ cfg_layout_merge_blocks (basic_block a, basic_block b)
       b->il.rtl->footer = NULL;
     }
 
+  /* If B was a forwarder block, propagate the locus on the edge.  */
+  if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus)
+    EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus;
+
   if (dump_file)
-    fprintf (dump_file, "Merged blocks %d and %d.\n",
-	     a->index, b->index);
+    fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index);
 }
 
 /* Split edge E.  */