Change the register allocator so that it no longer tracks references...

src/jump-target.cc

 // Copyright 2009 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 56 matching lines @@
     }
     ASSERT(!all_identical || all_identical);
   }
 #endif
 
   // Choose an initial frame.
   VirtualFrame* initial_frame = reaching_frames_[0];
 
   // A list of pointers to frame elements in the entry frame.  NULL
   // indicates that the element has not yet been determined.
-  int length = initial_frame->elements_.length();
+  int length = initial_frame->element_count();
   ZoneList<FrameElement*> elements(length);
 
   // Convert the number of mergable elements (counted from the top
   // down) to a frame high-water mark (counted from the bottom up).
   // Elements strictly above the high-water index will be mergable in
   // entry frames for bidirectional jump targets.
   int high_water_mark = (mergable_elements == kAllElements)
       ? VirtualFrame::kIllegalIndex  // All frame indices are above this.
       : length - mergable_elements - 1;  // Top index if m_e == 0.
 
@@ skipping 29 matching lines @@
       }
       elements[i] = element;
     }
   }
 
   // Build the new frame.  A freshly allocated frame has memory elements
   // for the parameters and some platform-dependent elements (e.g.,
   // return address).  Replace those first.
   entry_frame_ = new VirtualFrame();
   int index = 0;
-  for (; index < entry_frame_->elements_.length(); index++) {
+  for (; index < entry_frame_->element_count(); index++) {
     FrameElement* target = elements[index];
     // If the element is determined, set it now.  Count registers.  Mark
     // elements as copied exactly when they have a copy.  Undetermined
     // elements are initially recorded as if in memory.
     if (target != NULL) {
       entry_frame_->elements_[index] = *target;
       InitializeEntryElement(index, target);
     }
   }
   // Then fill in the rest of the frame with new elements.
@@ skipping 10 matching lines @@
   // Allocate any still-undetermined frame elements to registers or
   // memory, from the top down.
   for (int i = length - 1; i >= 0; i--) {
     if (elements[i] == NULL) {
       // Loop over all the reaching frames to check whether the element
       // is synced on all frames, to count the registers it occupies,
       // and to compute a merged static type.
       bool is_synced = true;
       RegisterFile candidate_registers;
       int best_count = kMinInt;
-      int best_reg_code = no_reg.code_;
+      int best_reg_num = RegisterAllocator::kInvalidRegister;
 
       StaticType type;  // Initially invalid.
       if (direction_ != BIDIRECTIONAL || i < high_water_mark) {
         type = reaching_frames_[0]->elements_[i].static_type();
       }
 
       for (int j = 0; j < reaching_frames_.length(); j++) {
         FrameElement element = reaching_frames_[j]->elements_[i];
         is_synced = is_synced && element.is_synced();
         if (element.is_register() && !entry_frame_->is_used(element.reg())) {
           // Count the register occurrence and remember it if better
           // than the previous best.
-          candidate_registers.Use(element.reg());
-          if (candidate_registers.count(element.reg()) > best_count) {
-            best_count = candidate_registers.count(element.reg());
-            best_reg_code = element.reg().code();
+          int num = RegisterAllocator::ToNumber(element.reg());
+          candidate_registers.Use(num);
+          if (candidate_registers.count(num) > best_count) {
+            best_count = candidate_registers.count(num);
+            best_reg_num = num;
           }
         }
         type = type.merge(element.static_type());
       }
 
       // If the value is synced on all frames, put it in memory.  This
       // costs nothing at the merge code but will incur a
       // memory-to-register move when the value is needed later.
       if (is_synced) {
         // Already recorded as a memory element.
         entry_frame_->elements_[i].set_static_type(type);
         continue;
       }
 
       // Try to put it in a register.  If there was no best choice
       // consider any free register.
-      if (best_reg_code == no_reg.code_) {
-        for (int j = 0; j < kNumRegisters; j++) {
-          if (!entry_frame_->is_used(j) && !RegisterAllocator::IsReserved(j)) {
-            best_reg_code = j;
+      if (best_reg_num == RegisterAllocator::kInvalidRegister) {
+        for (int j = 0; j < RegisterAllocator::kNumRegisters; j++) {
+          if (!entry_frame_->is_used(j)) {
+            best_reg_num = j;
             break;
           }
         }
       }
 
-      if (best_reg_code == no_reg.code_) {
+      if (best_reg_num == RegisterAllocator::kInvalidRegister) {
         // If there was no register found, the element is already
         // recorded as in memory.
         entry_frame_->elements_[i].set_static_type(type);
       } else {
         // If there was a register choice, use it.  Preserve the copied
         // flag on the element.  Set the static type as computed.
         bool is_copied = entry_frame_->elements_[i].is_copied();
-        Register reg = { best_reg_code };
+        Register reg = RegisterAllocator::ToRegister(best_reg_num);
         entry_frame_->elements_[i] =
             FrameElement::RegisterElement(reg,
                                           FrameElement::NOT_SYNCED);
         if (is_copied) entry_frame_->elements_[i].set_copied();
         entry_frame_->elements_[i].set_static_type(type);
-        entry_frame_->register_locations_[best_reg_code] = i;
+        entry_frame_->set_register_location(reg, i);
       }
     }
   }
 
   // The stack pointer is at the highest synced element or the base of
   // the expression stack.
   int stack_pointer = length - 1;
   while (stack_pointer >= entry_frame_->expression_base_index() &&
          !entry_frame_->elements_[stack_pointer].is_synced()) {
     stack_pointer--;
@@ skipping 378 matching lines @@
   temp.CopyTo(this);
   temp.Unuse();
 
 #ifdef DEBUG
   is_shadowing_ = false;
 #endif
 }
 
 
 } }  // namespace v8::internal