It would be easy to miss an entry either of the two visitors involved
that would result in trying to ir->remove() the call to remove it from
the instruction stream when really it's part of an expression tree
that wasn't flattened.
ir_function_inlining_visitor::visit_enter(ir_call *ir)
{
if (can_inline(ir)) {
+ /* If the call was part of some tree, then it should have been
+ * flattened out or we shouldn't have seen it because of a
+ * visit_continue_with_parent in this visitor.
+ */
+ assert(ir == base_ir);
+
(void) ir->generate_inline(ir);
ir->remove();
this->progress = true;