recognize dotimes (#310)

decompiler/IR2/Form.cpp

@@ -1969,4 +1969,74 @@ void LetElement::set_body(Form* new_body) {
   m_body->parent_element = this;
 }
 
+/////////////////////////////
+// DoTimesElement
+/////////////////////////////
+
+DoTimesElement::DoTimesElement(RegisterAccess var_init,
+                               RegisterAccess var_check,
+                               RegisterAccess var_inc,
+                               Form* check_value,
+                               Form* body)
+    : m_var_init(var_init),
+      m_var_check(var_check),
+      m_var_inc(var_inc),
+      m_check_value(check_value),
+      m_body(body) {
+  m_body->parent_element = this;
+  m_check_value->parent_element = this;
+  assert(m_var_inc.reg() == m_var_check.reg());
+  assert(m_var_init.reg() == m_var_inc.reg());
+}
+
+goos::Object DoTimesElement::to_form_internal(const Env& env) const {
+  std::vector<goos::Object> outer = {
+      pretty_print::to_symbol("dotimes"),
+      pretty_print::build_list(m_var_init.to_form(env), m_check_value->to_form(env))};
+  m_body->inline_forms(outer, env);
+  return pretty_print::build_list(outer);
+}
+
+void DoTimesElement::apply(const std::function<void(FormElement*)>& f) {
+  f(this);
+  m_check_value->apply(f);
+  m_body->apply(f);
+}
+
+void DoTimesElement::apply_form(const std::function<void(Form*)>& f) {
+  m_check_value->apply_form(f);
+  m_body->apply_form(f);
+}
+
+void DoTimesElement::collect_vars(RegAccessSet& vars, bool recursive) const {
+  vars.insert(m_var_init);
+  vars.insert(m_var_check);
+  vars.insert(m_var_inc);
+  if (recursive) {
+    m_body->collect_vars(vars, recursive);
+    m_check_value->collect_vars(vars, recursive);
+  }
+}
+
+void DoTimesElement::get_modified_regs(RegSet& regs) const {
+  regs.insert(m_var_inc.reg());
+  m_body->get_modified_regs(regs);
+  m_check_value->get_modified_regs(regs);
+}
+
+std::optional<SimpleAtom> form_as_atom(const Form* f) {
+  auto as_single = f->try_as_single_element();
+  auto as_atom = dynamic_cast<SimpleAtomElement*>(as_single);
+  if (as_atom) {
+    return as_atom->atom();
+  }
+
+  auto as_se = dynamic_cast<SimpleExpressionElement*>(as_single);
+  if (as_se && as_se->expr().is_identity()) {
+    return as_se->expr().get_arg(0);
+  }
+
+  return {};
+}
+
 }  // namespace decompiler