Fix two bugs in LiveRange::SplitAt:

src/lithium-allocator.cc

 // Copyright 2010 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 285 matching lines @@
   ASSERT(result->IsEmpty());
   // Find the last interval that ends before the position. If the
   // position is contained in one of the intervals in the chain, we
   // split that interval and use the first part.
   UseInterval* current = FirstSearchIntervalForPosition(position);
 
   // If the split position coincides with the beginning of a use interval
   // we need to split use positons in a special way.
   bool split_at_start = false;
 
+  if (current->start().Value() == position.Value()) {
+    // When splitting at start we need to locate the previous use interval.
+    current = first_interval_;
+  }
+
   while (current != NULL) {
     if (current->Contains(position)) {
       current->SplitAt(position);
       break;
     }
     UseInterval* next = current->next();
     if (next->start().Value() >= position.Value()) {
       split_at_start = (next->start().Value() == position.Value());
       break;
     }
@@ skipping 29 matching lines @@
   }
 
   // Partition original use positions to the two live ranges.
   if (use_before != NULL) {
     use_before->next_ = NULL;
   } else {
     first_pos_ = NULL;
   }
   result->first_pos_ = use_after;
 
+  // Discard cached iteration state. It might be pointing
+  // to the use that no longer belongs to this live range.
+  last_processed_use_ = NULL;
+  current_interval_ = NULL;
+
   // Link the new live range in the chain before any of the other
   // ranges linked from the range before the split.
   result->parent_ = (parent_ == NULL) ? this : parent_;
   result->next_ = next_;
   next_ = result;
 
 #ifdef DEBUG
   Verify();
   result->Verify();
 #endif
@@ skipping 1749 matching lines @@
     LiveRange* current = live_ranges()->at(i);
     if (current != NULL) current->Verify();
   }
 }
 
 
 #endif
 
 
 } }  // namespace v8::internal