Experimental: eagerly allocate space in the actual frame for spilling...

src/virtual-frame-ia32.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 188 matching lines @@
   }
 
   frame_pointer_ = kIllegalIndex;
   EmitPop(ebp);
 }
 
 
 void VirtualFrame::AllocateStackSlots(int count) {
   ASSERT(height() == 0);
   local_count_ = count;
-  for (int i = 0; i < count; i++) {
-    elements_.Add(FrameElement(Factory::undefined_value()));
+
+  if (count > 0) {
+    Comment cmnt(masm_, "[ Allocate space for locals");
+    // The locals are constants (the undefined value), but we sync them with
+    // the actual frame to allocate space for spilling them.
+    FrameElement initial_value(Factory::undefined_value());
+    initial_value.clear_dirty();
+    __ Set(eax, Immediate(Factory::undefined_value()));
+    for (int i = 0; i < count; i++) {
+      elements_.Add(initial_value);
+      stack_pointer_++;
+      __ push(eax);
+    }
   }
 }
 
 
 void VirtualFrame::PushTryHandler(HandlerType type) {
   // Grow the expression stack by handler size less two (the return address
   // is already pushed by a call instruction, and PushTryHandler from the
   // macro assembler will leave the top of stack in the eax register to be
   // pushed separately).
   Adjust(kHandlerSize - 2);
@@ skipping 92 matching lines @@
   ASSERT(stack_pointer_ == elements_.length() - 1);
   elements_.Add(FrameElement());
   stack_pointer_++;
   __ push(immediate);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal