re PR tree-optimization/56982 (Bad optimization with setjmp())

2013-04-19  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/56982
	* builtins.def (BUILT_IN_LONGJMP): longjmp is not a leaf
	function.
	* gimplify.c (gimplify_call_expr): Notice special calls.
	(gimplify_modify_expr): Likewise.
	* tree-cfg.c (make_abnormal_goto_edges): Handle setjmp-like
	abnormal control flow receivers.
	(call_can_make_abnormal_goto): Handle cfun->calls_setjmp
	in the same way as cfun->has_nonlocal_labels.
	(gimple_purge_dead_abnormal_call_edges): Likewise.
	(stmt_starts_bb_p): Make setjmp-like abnormal control flow
	receivers start a basic-block.

	* gcc.c-torture/execute/pr56982.c: New testcase.

From-SVN: r198096

1 files changed, 34 insertions, 17 deletions

diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 8a36976..05bac43 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -967,25 +967,35 @@ make_abnormal_goto_edges (basic_block bb, bool for_call)
   gimple_stmt_iterator gsi;
 
   FOR_EACH_BB (target_bb)
-    for (gsi = gsi_start_bb (target_bb); !gsi_end_p (gsi); gsi_next (&gsi))
-      {
-	gimple label_stmt = gsi_stmt (gsi);
-	tree target;
+    {
+      for (gsi = gsi_start_bb (target_bb); !gsi_end_p (gsi); gsi_next (&gsi))
+	{
+	  gimple label_stmt = gsi_stmt (gsi);
+	  tree target;
 
-	if (gimple_code (label_stmt) != GIMPLE_LABEL)
-	  break;
+	  if (gimple_code (label_stmt) != GIMPLE_LABEL)
+	    break;
 
-	target = gimple_label_label (label_stmt);
+	  target = gimple_label_label (label_stmt);
 
-	/* Make an edge to every label block that has been marked as a
-	   potential target for a computed goto or a non-local goto.  */
-	if ((FORCED_LABEL (target) && !for_call)
-	    || (DECL_NONLOCAL (target) && for_call))
-	  {
+	  /* Make an edge to every label block that has been marked as a
+	     potential target for a computed goto or a non-local goto.  */
+	  if ((FORCED_LABEL (target) && !for_call)
+	      || (DECL_NONLOCAL (target) && for_call))
+	    {
+	      make_edge (bb, target_bb, EDGE_ABNORMAL);
+	      break;
+	    }
+	}
+      if (!gsi_end_p (gsi))
+	{
+	  /* Make an edge to every setjmp-like call.  */
+	  gimple call_stmt = gsi_stmt (gsi);
+	  if (is_gimple_call (call_stmt)
+	      && (gimple_call_flags (call_stmt) & ECF_RETURNS_TWICE))
 	    make_edge (bb, target_bb, EDGE_ABNORMAL);
-	    break;
-	  }
-      }
+	}
+    }
 }
 
 /* Create edges for a goto statement at block BB.  */
@@ -2147,7 +2157,8 @@ call_can_make_abnormal_goto (gimple t)
 {
   /* If the function has no non-local labels, then a call cannot make an
      abnormal transfer of control.  */
-  if (!cfun->has_nonlocal_label)
+  if (!cfun->has_nonlocal_label
+      && !cfun->calls_setjmp)
    return false;
 
   /* Likewise if the call has no side effects.  */
@@ -2302,6 +2313,11 @@ stmt_starts_bb_p (gimple stmt, gimple prev_stmt)
       else
 	return true;
     }
+  else if (gimple_code (stmt) == GIMPLE_CALL
+	   && gimple_call_flags (stmt) & ECF_RETURNS_TWICE)
+    /* setjmp acts similar to a nonlocal GOTO target and thus should
+       start a new block.  */
+    return true;
 
   return false;
 }
@@ -7532,7 +7548,8 @@ gimple_purge_dead_abnormal_call_edges (basic_block bb)
   edge_iterator ei;
   gimple stmt = last_stmt (bb);
 
-  if (!cfun->has_nonlocal_label)
+  if (!cfun->has_nonlocal_label
+      && !cfun->calls_setjmp)
     return false;
 
   if (stmt && stmt_can_make_abnormal_goto (stmt))