1 files changed, 41 insertions, 12 deletions

diff --git a/gcc/cfgbuild.c b/gcc/cfgbuild.c
index 69ca1282c37..238954a1cfa 100644
--- a/gcc/cfgbuild.c
+++ b/gcc/cfgbuild.c
@@ -442,9 +442,10 @@ find_bb_boundaries (basic_block bb)
   rtx_insn *end = BB_END (bb), *x;
   rtx_jump_table_data *table;
   rtx_insn *flow_transfer_insn = NULL;
+  rtx_insn *debug_insn = NULL;
   edge fallthru = NULL;
 
-  if (insn == BB_END (bb))
+  if (insn == end)
     return;
 
   if (LABEL_P (insn))
@@ -455,27 +456,49 @@ find_bb_boundaries (basic_block bb)
     {
       enum rtx_code code = GET_CODE (insn);
 
+      if (code == DEBUG_INSN)
+	{
+	  if (flow_transfer_insn && !debug_insn)
+	    debug_insn = insn;
+	}
       /* In case we've previously seen an insn that effects a control
 	 flow transfer, split the block.  */
-      if ((flow_transfer_insn || code == CODE_LABEL)
-	  && inside_basic_block_p (insn))
+      else if ((flow_transfer_insn || code == CODE_LABEL)
+	       && inside_basic_block_p (insn))
 	{
-	  fallthru = split_block (bb, PREV_INSN (insn));
+	  rtx_insn *prev = PREV_INSN (insn);
+
+	  /* If the first non-debug inside_basic_block_p insn after a control
+	     flow transfer is not a label, split the block before the debug
+	     insn instead of before the non-debug insn, so that the debug
+	     insns are not lost.  */
+	  if (debug_insn && code != CODE_LABEL && code != BARRIER)
+	    prev = PREV_INSN (debug_insn);
+	  fallthru = split_block (bb, prev);
 	  if (flow_transfer_insn)
 	    {
 	      BB_END (bb) = flow_transfer_insn;
 
+	      rtx_insn *next;
 	      /* Clean up the bb field for the insns between the blocks.  */
 	      for (x = NEXT_INSN (flow_transfer_insn);
 		   x != BB_HEAD (fallthru->dest);
-		   x = NEXT_INSN (x))
-		if (!BARRIER_P (x))
-		  set_block_for_insn (x, NULL);
+		   x = next)
+		{
+		  next = NEXT_INSN (x);
+		  /* Debug insns should not be in between basic blocks,
+		     drop them on the floor.  */
+		  if (DEBUG_INSN_P (x))
+		    delete_insn (x);
+		  else if (!BARRIER_P (x))
+		    set_block_for_insn (x, NULL);
+		}
 	    }
 
 	  bb = fallthru->dest;
 	  remove_edge (fallthru);
 	  flow_transfer_insn = NULL;
+	  debug_insn = NULL;
 	  if (code == CODE_LABEL && LABEL_ALT_ENTRY_P (insn))
 	    make_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun), bb, 0);
 	}
@@ -498,17 +521,23 @@ find_bb_boundaries (basic_block bb)
   /* In case expander replaced normal insn by sequence terminating by
      return and barrier, or possibly other sequence not behaving like
      ordinary jump, we need to take care and move basic block boundary.  */
-  if (flow_transfer_insn)
+  if (flow_transfer_insn && flow_transfer_insn != end)
     {
       BB_END (bb) = flow_transfer_insn;
 
       /* Clean up the bb field for the insns that do not belong to BB.  */
-      x = flow_transfer_insn;
-      while (x != end)
+      rtx_insn *next;
+      for (x = NEXT_INSN (flow_transfer_insn); ; x = next)
 	{
-	  x = NEXT_INSN (x);
-	  if (!BARRIER_P (x))
+	  next = NEXT_INSN (x);
+	  /* Debug insns should not be in between basic blocks,
+	     drop them on the floor.  */
+	  if (DEBUG_INSN_P (x))
+	    delete_insn (x);
+	  else if (!BARRIER_P (x))
 	    set_block_for_insn (x, NULL);
+	  if (x == end)
+	    break;
 	}
     }