Clean up Scope::CollectUsedVariables.

src/liveedit.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 837 matching lines @@
     int scope_info_length = 0;
 
     // Saves some description of scope. It stores name and indexes of
     // variables in the whole scope chain. Null-named slots delimit
     // scopes of this chain.
     Scope* outer_scope = scope->outer_scope();
     if (outer_scope == NULL) {
       return HEAP->undefined_value();
     }
     do {
-      ZoneList<Variable*> list(10);
-      outer_scope->CollectUsedVariables(&list);
-      int j = 0;
-      for (int i = 0; i < list.length(); i++) {
-        Variable* var1 = list[i];
-        if (var1->IsContextSlot()) {
-          if (j != i) {
-            list[j] = var1;
-          }
-          j++;
-        }
-      }
+      ZoneList<Variable*> stack_list(outer_scope->StackLocalCount());
+      ZoneList<Variable*> context_list(outer_scope->ContextLocalCount());
+      outer_scope->CollectStackAndContextLocals(&stack_list, &context_list);
 
       // Sort it.
-      for (int k = 1; k < j; k++) {
+      for (int k = 1; k < context_list.length(); k++) {

[Steven, 2011/11/03 12:39:39]

Why does the iteration start at 1 here? Is this maybe a bug?

[Kevin Millikin (Chromium), 2011/11/03 13:12:20]

It does look like a bug.  I'm not even sure whether it's a one or an L.  In any
case, it's more obviously correct to have:

context_list.Sort(&CompareLocal)

and expose CompareLocal from scopes.cc (I'd put CompareLocal in in
variables.{h,cc} if it were me, and I'd rename it to CompareIndex or something).

[Steven, 2011/11/03 14:55:59]

Done.

         int l = k;
-        for (int m = k + 1; m < j; m++) {
-          if (list[l]->index() > list[m]->index()) {
+        for (int m = k + 1; m < context_list.length(); m++) {
+          if (context_list[l]->index() > context_list[m]->index()) {
             l = m;
           }
         }
-        list[k] = list[l];
+        context_list[k] = context_list[l];

[Steven, 2011/11/03 14:55:59]

Honestly this whole code looks like a giant bug to me. This is sort of supposed
to be some kind of selection sort, but here one entry is copied over another one
instead of being swapped or so.

       }
-      for (int i = 0; i < j; i++) {
+      for (int i = 0; i < context_list.length(); i++) {
         SetElementNonStrict(scope_info_list,
                             scope_info_length,
-                            list[i]->name());
+                            context_list[i]->name());
         scope_info_length++;
         SetElementNonStrict(
             scope_info_list,
             scope_info_length,
-            Handle<Smi>(Smi::FromInt(list[i]->index())));
+            Handle<Smi>(Smi::FromInt(context_list[i]->index())));
         scope_info_length++;
       }
       SetElementNonStrict(scope_info_list,
                           scope_info_length,
                           Handle<Object>(HEAP->null_value()));
       scope_info_length++;
 
       outer_scope = outer_scope->outer_scope();
     } while (outer_scope != NULL);
 
@@ skipping 882 matching lines @@
 
 bool LiveEditFunctionTracker::IsActive(Isolate* isolate) {
   return false;
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 
 } }  // namespace v8::internal