known_condition_false
int known_condition_false(struct expression *expr);
if (known_condition_false(stmt->if_conditional)) {
if (known_condition_false(expr->conditional)) {
if (known_condition_false(expr->conditional)) {
if (known_condition_false(expr->unop)) {
if (known_condition_false(expr))
if (known_condition_false(expr->conditional))
if (known_condition_false(expr->conditional))