Capture register clearing on loop iteration

src/ast.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 192 matching lines @@
   RegExp##Name* RegExp##Name::As##Name() {                          \
     return this;                                                    \
   }                                                                 \
   bool RegExp##Name::Is##Name() { return true; }
 FOR_EACH_REG_EXP_TREE_TYPE(MAKE_TYPE_CASE)
 #undef MAKE_TYPE_CASE
 
 RegExpEmpty RegExpEmpty::kInstance;
 
 
+static Interval ListCaptureRegisters(ZoneList<RegExpTree*>* children) {
+  Interval result = Interval::Empty();
+  for (int i = 0; i < children->length(); i++)
+    result = result.Union(children->at(i)->CaptureRegisters());
+  return result;
+}
+
+
+Interval RegExpAlternative::CaptureRegisters() {
+  return ListCaptureRegisters(nodes());
+}
+
+
+Interval RegExpDisjunction::CaptureRegisters() {
+  return ListCaptureRegisters(alternatives());
+}
+
+
+Interval RegExpLookahead::CaptureRegisters() {
+  return body()->CaptureRegisters();
+}
+
+
+Interval RegExpCapture::CaptureRegisters() {
+  Interval self(StartRegister(index()), EndRegister(index()));
+  return self.Union(body()->CaptureRegisters());
+}
+
+
+Interval RegExpQuantifier::CaptureRegisters() {
+  return body()->CaptureRegisters();
+}
+
+
 // Convert regular expression trees to a simple sexp representation.
 // This representation should be different from the input grammar
 // in as many cases as possible, to make it more difficult for incorrect
 // parses to look as correct ones which is likely if the input and
 // output formats are alike.
 class RegExpUnparser: public RegExpVisitor {
  public:
   RegExpUnparser();
   void VisitCharacterRange(CharacterRange that);
   SmartPointer<const char> ToString() { return stream_.ToCString(); }
@@ skipping 182 matching lines @@
     if (kInfinity - max_match_ < node_max_match) {
       max_match_ = kInfinity;
     } else {
       max_match_ += node->max_match();
     }
   }
 }
 
 
 } }  // namespace v8::internal