Introduce scopes to keep track of catch blocks at compile time.

src/scopes.cc

 // Copyright 2011 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 238 matching lines @@
   }
 
   // Declare convenience variables.
   // Declare and allocate receiver (even for the global scope, and even
   // if naccesses_ == 0).
   // NOTE: When loading parameters in the global scope, we must take
   // care not to access them as properties of the global object, but
   // instead load them directly from the stack. Currently, the only
   // such parameter is 'this' which is passed on the stack when
   // invoking scripts
-  Variable* var =
-      variables_.Declare(this, FACTORY->this_symbol(), Variable::VAR,
-                         false, Variable::THIS);
-  var->set_rewrite(new Slot(var, Slot::PARAMETER, -1));
-  receiver_ = var;
+  if (is_catch_scope()) {
+    ASSERT(outer_scope() != NULL);
+    receiver_ = outer_scope()->receiver();
+  } else {
+    Variable* var =
+        variables_.Declare(this, FACTORY->this_symbol(), Variable::VAR,
+                           false, Variable::THIS);
+    var->set_rewrite(new Slot(var, Slot::PARAMETER, -1));
+    receiver_ = var;
+  }
 
   if (is_function_scope()) {
     // Declare 'arguments' variable which exists in all functions.
     // Note that it might never be accessed, in which case it won't be
     // allocated during variable allocation.
     variables_.Declare(this, FACTORY->arguments_symbol(), Variable::VAR,
                        true, Variable::ARGUMENTS);
   }
 }
 
@@ skipping 233 matching lines @@
   return n;
 }
 
 
 #ifdef DEBUG
 static const char* Header(Scope::Type type) {
   switch (type) {
     case Scope::EVAL_SCOPE: return "eval";
     case Scope::FUNCTION_SCOPE: return "function";
     case Scope::GLOBAL_SCOPE: return "global";
+    case Scope::CATCH_SCOPE: return "catch";
   }
   UNREACHABLE();
   return NULL;
 }
 
 
 static void Indent(int n, const char* str) {
   PrintF("%*s%s", n, "", str);
 }
 
@@ skipping 330 matching lines @@
   return scope_calls_eval_ || inner_scope_calls_eval_;
 }
 
 
 bool Scope::MustAllocate(Variable* var) {
   // Give var a read/write use if there is a chance it might be accessed
   // via an eval() call.  This is only possible if the variable has a
   // visible name.
   if ((var->is_this() || var->name()->length() > 0) &&
       (var->is_accessed_from_inner_scope() ||
-       scope_calls_eval_ || inner_scope_calls_eval_ ||
-       scope_contains_with_)) {
+       scope_calls_eval_ ||
+       inner_scope_calls_eval_ ||
+       scope_contains_with_ ||
+       is_catch_scope())) {
     var->set_is_used(true);
   }
   // Global variables do not need to be allocated.
   return !var->is_global() && var->is_used();
 }
 
 
 bool Scope::MustAllocateInContext(Variable* var) {
-  // If var is accessed from an inner scope, or if there is a
-  // possibility that it might be accessed from the current or an inner
-  // scope (through an eval() call), it must be allocated in the
-  // context.  Exception: temporary variables are not allocated in the
+  // If var is accessed from an inner scope, or if there is a possibility
+  // that it might be accessed from the current or an inner scope (through
+  // an eval() call or a runtime with lookup), it must be allocated in the
   // context.
-  return
-    var->mode() != Variable::TEMPORARY &&
-    (var->is_accessed_from_inner_scope() ||
-     scope_calls_eval_ || inner_scope_calls_eval_ ||
-     scope_contains_with_ || var->is_global());
+  //
+  // Exceptions: temporary variables are never allocated in a context;
+  // catch-bound variables are always allocated in a context.
+  if (var->mode() == Variable::TEMPORARY) return false;
+  if (is_catch_scope()) return true;
+  return var->is_accessed_from_inner_scope() ||
+      scope_calls_eval_ ||
+      inner_scope_calls_eval_ ||
+      scope_contains_with_ ||
+      var->is_global();
 }
 
 
 bool Scope::HasArgumentsParameter() {
   for (int i = 0; i < params_.length(); i++) {
     if (params_[i]->name().is_identical_to(FACTORY->arguments_symbol()))
       return true;
   }
   return false;
 }
@@ skipping 139 matching lines @@
   if (num_heap_slots_ == Context::MIN_CONTEXT_SLOTS &&
       !must_have_local_context) {
     num_heap_slots_ = 0;
   }
 
   // Allocation done.
   ASSERT(num_heap_slots_ == 0 || num_heap_slots_ >= Context::MIN_CONTEXT_SLOTS);
 }
 
 } }  // namespace v8::internal