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Re: [Bug c/18602] segfault on a huge switch statement.


> Confirmed, the problem is because of stack overflow.  Either
> splay_tree_delete_helper needs a little help or the C/C++ front-end
> needs to stop using splay trees.

How about this?

/* Deallocate NODE (a member of SP), and all its sub-trees.  */

static void 
splay_tree_delete_helper (sp, node)
     splay_tree sp;
     splay_tree_node node;
{
  splay_tree_node pending = 0;
  splay_tree_node active = 0;

  if (!node)
    return;

#define KDEL(x)  if (sp->delete_key) (*sp->delete_key)(x);
#define VDEL(x)  if (sp->delete_value) (*sp->delete_value)(x);

  KDEL (node->key);
  VDEL (node->value);

  /* We use the "key" field to hold the "next" pointer.  */
  node->key = (splay_tree_key)pending;
  pending = (splay_tree_node)node;

  /* Now, keep processing the pending list until there aren't any
     more.  This is a little more complicated than just recursing, but
     it doesn't toast the stack for large trees.  */

  while (pending)
    {
      active = pending;
      pending = 0;
      while (active)
	{
	  splay_tree_node temp;

	  /* active points to a node which has its key and value
	     deallocated, we just need to process left and right.  */

	  if (active->left)
	    {
	      KDEL (active->left->key);
	      VDEL (active->left->value);
	      active->left->key = (splay_tree_key)pending;
	      pending = (splay_tree_node)(active->left);
	    }
	  if (active->right)
	    {
	      KDEL (active->right->key);
	      VDEL (active->right->value);
	      active->right->key = (splay_tree_key)pending;
	      pending = (splay_tree_node)(active->right);
	    }

	  temp = active;
	  active = (splay_tree_node)(temp->key);
	  (*sp->deallocate) ((char*) temp, sp->allocate_data);
	}
    }
#undef KDEL
#undef VDEL
}


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