re PR tree-optimization/86214 (Strongly increased stack usage)

	PR tree-optimization/86214
	* cfgexpand.c (add_stack_var_conflict): Don't add any conflicts
	if x == y.

From-SVN: r268009

gcc/ChangeLog

 2019-01-17  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/86214
+	* cfgexpand.c (add_stack_var_conflict): Don't add any conflicts
+	if x == y.
+
 	PR rtl-optimization/88870
 	* dce.c (deletable_insn_p): Never delete const/pure calls that can
 	throw if we can't alter the cfg or delete dead exceptions.

gcc/cfgexpand.c

@@ -470,6 +470,8 @@ add_stack_var_conflict (size_t x, size_t y)
 {
   struct stack_var *a = &stack_vars[x];
   struct stack_var *b = &stack_vars[y];
+  if (x == y)
+    return;
   if (!a->conflicts)
     a->conflicts = BITMAP_ALLOC (&stack_var_bitmap_obstack);
   if (!b->conflicts)