Fix issue 265 by handling extra statement state on the frame based on...

src/virtual-frame-arm.cc

 // Copyright 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 150 matching lines @@
   if (stack_pointer_ < expected->stack_pointer_) {
     int difference = expected->stack_pointer_ - stack_pointer_;
     stack_pointer_ = expected->stack_pointer_;
     __ sub(sp, sp, Operand(difference * kPointerSize));
   }
 
   MergeMoveRegistersToMemory(expected);
   MergeMoveRegistersToRegisters(expected);
   MergeMoveMemoryToRegisters(expected);
 
-  // Fix any sync bit problems.
-  for (int i = 0; i <= stack_pointer_; i++) {
+  // Fix any sync bit problems from the bottom-up, stopping when we
+  // hit the stack pointer or the top of the frame if the stack
+  // pointer is floating above the frame.
+  int limit = Min(stack_pointer_, elements_.length() - 1);
+  for (int i = 0; i <= limit; i++) {
     FrameElement source = elements_[i];
     FrameElement target = expected->elements_[i];
     if (source.is_synced() && !target.is_synced()) {
       elements_[i].clear_sync();
     } else if (!source.is_synced() && target.is_synced()) {
       SyncElementAt(i);
     }
   }
 
   // Adjust the stack point downard if necessary.
   if (stack_pointer_ > expected->stack_pointer_) {
     int difference = stack_pointer_ - expected->stack_pointer_;
     stack_pointer_ = expected->stack_pointer_;
     __ add(sp, sp, Operand(difference * kPointerSize));
   }
 
   // At this point, the frames should be identical.
   ASSERT(Equals(expected));
 }
 
 
 void VirtualFrame::MergeMoveRegistersToMemory(VirtualFrame* expected) {
   ASSERT(stack_pointer_ >= expected->stack_pointer_);
 
   // Move registers, constants, and copies to memory.  Perform moves
   // from the top downward in the frame in order to leave the backing
   // stores of copies in registers.
-  //
-  // Moving memory-backed copies to memory requires a spare register
-  // for the memory-to-memory moves.  Since we are performing a merge,
-  // we use esi (which is already saved in the frame).  We keep track
-  // of the index of the frame element esi is caching or kIllegalIndex
-  // if esi has not been disturbed.
+  // On ARM, all elements are in memory.
 
-  for (int i = 0; i < elements_.length(); i++) {
+#ifdef DEBUG
+  int start = Min(stack_pointer_, elements_.length() - 1);
+  for (int i = start; i >= 0; i--) {
     ASSERT(elements_[i].is_memory());
     ASSERT(expected->elements_[i].is_memory());
   }
+#endif
 }
 
 
 void VirtualFrame::MergeMoveRegistersToRegisters(VirtualFrame* expected) {
 }
 
 
 void VirtualFrame::MergeMoveMemoryToRegisters(VirtualFrame *expected) {
 }
 
@@ skipping 251 matching lines @@
   ASSERT(stack_pointer_ == elements_.length() - 1);
   elements_.Add(FrameElement::MemoryElement());
   stack_pointer_++;
   __ push(reg);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal