1 files changed, 63 insertions, 38 deletions

diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 48fbe52..ae5335b 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -636,6 +636,67 @@ make_blocks_1 (gimple_seq seq, basic_block bb)
 static void
 make_blocks (gimple_seq seq)
 {
+  /* Look for debug markers right before labels, and move the debug
+     stmts after the labels.  Accepting labels among debug markers
+     adds no value, just complexity; if we wanted to annotate labels
+     with view numbers (so sequencing among markers would matter) or
+     somesuch, we're probably better off still moving the labels, but
+     adding other debug annotations in their original positions or
+     emitting nonbind or bind markers associated with the labels in
+     the original position of the labels.
+
+     Moving labels would probably be simpler, but we can't do that:
+     moving labels assigns label ids to them, and doing so because of
+     debug markers makes for -fcompare-debug and possibly even codegen
+     differences.  So, we have to move the debug stmts instead.  To
+     that end, we scan SEQ backwards, marking the position of the
+     latest (earliest we find) label, and moving debug stmts that are
+     not separated from it by nondebug nonlabel stmts after the
+     label.  */
+  if (MAY_HAVE_DEBUG_MARKER_STMTS)
+    {
+      gimple_stmt_iterator label = gsi_none ();
+
+      for (gimple_stmt_iterator i = gsi_last (seq); !gsi_end_p (i); gsi_prev (&i))
+	{
+	  gimple *stmt = gsi_stmt (i);
+
+	  /* If this is the first label we encounter (latest in SEQ)
+	     before nondebug stmts, record its position.  */
+	  if (is_a <glabel *> (stmt))
+	    {
+	      if (gsi_end_p (label))
+		label = i;
+	      continue;
+	    }
+
+	  /* Without a recorded label position to move debug stmts to,
+	     there's nothing to do.  */
+	  if (gsi_end_p (label))
+	    continue;
+
+	  /* Move the debug stmt at I after LABEL.  */
+	  if (is_gimple_debug (stmt))
+	    {
+	      gcc_assert (gimple_debug_nonbind_marker_p (stmt));
+	      /* As STMT is removed, I advances to the stmt after
+		 STMT, so the gsi_prev in the for "increment"
+		 expression gets us to the stmt we're to visit after
+		 STMT.  LABEL, however, would advance to the moved
+		 stmt if we passed it to gsi_move_after, so pass it a
+		 copy instead, so as to keep LABEL pointing to the
+		 LABEL.  */
+	      gimple_stmt_iterator copy = label;
+	      gsi_move_after (&i, &copy);
+	      continue;
+	    }
+
+	  /* There aren't any (more?) debug stmts before label, so
+	     there isn't anything else to move after it.  */
+	  label = gsi_none ();
+	}
+    }
+
   make_blocks_1 (seq, ENTRY_BLOCK_PTR_FOR_FN (cfun));
 }
 
@@ -1005,11 +1066,7 @@ make_edges (void)
 	      tree target;
 
 	      if (!label_stmt)
-		{
-		  if (is_gimple_debug (gsi_stmt (gsi)))
-		    continue;
-		  break;
-		}
+		break;
 
 	      target = gimple_label_label (label_stmt);
 
@@ -1519,9 +1576,6 @@ cleanup_dead_labels (void)
 
       for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
 	{
-	  if (is_gimple_debug (gsi_stmt (i)))
-	    continue;
-
 	  tree label;
 	  glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (i));
 
@@ -1682,12 +1736,6 @@ cleanup_dead_labels (void)
 
       for (i = gsi_start_bb (bb); !gsi_end_p (i); )
 	{
-	  if (is_gimple_debug (gsi_stmt (i)))
-	    {
-	      gsi_next (&i);
-	      continue;
-	    }
-
 	  tree label;
 	  glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (i));
 
@@ -1863,8 +1911,6 @@ gimple_can_merge_blocks_p (basic_block a, basic_block b)
        gsi_next (&gsi))
     {
       tree lab;
-      if (is_gimple_debug (gsi_stmt (gsi)))
-	continue;
       glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gsi));
       if (!label_stmt)
 	break;
@@ -5431,7 +5477,6 @@ verify_gimple_in_cfg (struct function *fn, bool verify_nothrow)
 	  err |= err2;
 	}
 
-      bool label_allowed = true;
       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 	{
 	  gimple *stmt = gsi_stmt (gsi);
@@ -5448,19 +5493,6 @@ verify_gimple_in_cfg (struct function *fn, bool verify_nothrow)
 	      err2 = true;
 	    }
 
-	  /* Labels may be preceded only by debug markers, not debug bind
-	     or source bind or any other statements.  */
-	  if (gimple_code (stmt) == GIMPLE_LABEL)
-	    {
-	      if (!label_allowed)
-		{
-		  error ("gimple label in the middle of a basic block");
-		  err2 = true;
-		}
-	    }
-	  else if (!gimple_debug_begin_stmt_p (stmt))
-	    label_allowed = false;
-
 	  err2 |= verify_gimple_stmt (stmt);
 	  err2 |= verify_location (&blocks, gimple_location (stmt));
 
@@ -5584,10 +5616,6 @@ gimple_verify_flow_info (void)
       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 	{
 	  tree label;
-
-	  if (is_gimple_debug (gsi_stmt (gsi)))
-	    continue;
-
 	  gimple *prev_stmt = stmt;
 
 	  stmt = gsi_stmt (gsi);
@@ -5912,10 +5940,8 @@ gimple_block_label (basic_block bb)
   tree label;
   glabel *stmt;
 
-  for (i = s; !gsi_end_p (i); gsi_next (&i))
+  for (i = s; !gsi_end_p (i); first = false, gsi_next (&i))
     {
-      if (is_gimple_debug (gsi_stmt (i)))
-	continue;
       stmt = dyn_cast <glabel *> (gsi_stmt (i));
       if (!stmt)
 	break;
@@ -5926,7 +5952,6 @@ gimple_block_label (basic_block bb)
 	    gsi_move_before (&i, &s);
 	  return label;
 	}
-      first = false;
     }
 
   label = create_artificial_label (UNKNOWN_LOCATION);