Split the virtual frame into heavy and light versions....

src/virtual-frame.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 19 matching lines @@
 #include "codegen-inl.h"
 #include "register-allocator-inl.h"
 #include "virtual-frame-inl.h"
 
 namespace v8 {
 namespace internal {
 
 // -------------------------------------------------------------------------
 // VirtualFrame implementation.
 
-// Create a duplicate of an existing valid frame element.
-// We can pass an optional number type information that will override the
-// existing information about the backing element. The new information must
-// not conflict with the existing type information and must be equally or
-// more precise. The default parameter value kUninitialized means that there
-// is no additional information.
-FrameElement VirtualFrame::CopyElementAt(int index, NumberInfo info) {
-  ASSERT(index >= 0);
-  ASSERT(index < element_count());
-
-  FrameElement target = elements_[index];
-  FrameElement result;
-
-  switch (target.type()) {
-    case FrameElement::CONSTANT:
-      // We do not copy constants and instead return a fresh unsynced
-      // constant.
-      result = FrameElement::ConstantElement(target.handle(),
-                                             FrameElement::NOT_SYNCED);
-      break;
-
-    case FrameElement::COPY:
-      // We do not allow copies of copies, so we follow one link to
-      // the actual backing store of a copy before making a copy.
-      index = target.index();
-      ASSERT(elements_[index].is_memory() || elements_[index].is_register());
-      // Fall through.
-
-    case FrameElement::MEMORY:  // Fall through.
-    case FrameElement::REGISTER: {
-      // All copies are backed by memory or register locations.
-      result.set_type(FrameElement::COPY);
-      result.clear_copied();
-      result.clear_sync();
-      result.set_index(index);
-      elements_[index].set_copied();
-      // Update backing element's number information.
-      NumberInfo existing = elements_[index].number_info();
-      ASSERT(!existing.IsUninitialized());
-      // Assert that the new type information (a) does not conflict with the
-      // existing one and (b) is equally or more precise.
-      ASSERT((info.ToInt() & existing.ToInt()) == existing.ToInt());
-      ASSERT((info.ToInt() | existing.ToInt()) == info.ToInt());
-
-      elements_[index].set_number_info(!info.IsUninitialized()
-                                       ? info
-                                       : existing);
-      break;
-    }
-    case FrameElement::INVALID:
-      // We should not try to copy invalid elements.
-      UNREACHABLE();
-      break;
-  }
-  return result;
-}
-
-
-// Modify the state of the virtual frame to match the actual frame by adding
-// extra in-memory elements to the top of the virtual frame.  The extra
-// elements will be externally materialized on the actual frame (eg, by
-// pushing an exception handler).  No code is emitted.
-void VirtualFrame::Adjust(int count) {
-  ASSERT(count >= 0);
-  ASSERT(stack_pointer_ == element_count() - 1);
-
-  for (int i = 0; i < count; i++) {
-    elements_.Add(FrameElement::MemoryElement(NumberInfo::Unknown()));
-  }
-  stack_pointer_ += count;
-}
-
-
-void VirtualFrame::ForgetElements(int count) {
-  ASSERT(count >= 0);
-  ASSERT(element_count() >= count);
-
-  for (int i = 0; i < count; i++) {
-    FrameElement last = elements_.RemoveLast();
-    if (last.is_register()) {
-      // A hack to properly count register references for the code
-      // generator's current frame and also for other frames.  The
-      // same code appears in PrepareMergeTo.
-      if (cgen()->frame() == this) {
-        Unuse(last.reg());
-      } else {
-        set_register_location(last.reg(), kIllegalIndex);
-      }
-    }
-  }
-}
-
-
 // If there are any registers referenced only by the frame, spill one.
 Register VirtualFrame::SpillAnyRegister() {
   // Find the leftmost (ordered by register number) register whose only
   // reference is in the frame.
   for (int i = 0; i < RegisterAllocator::kNumRegisters; i++) {
     if (is_used(i) && cgen()->allocator()->count(i) == 1) {
       SpillElementAt(register_location(i));
       ASSERT(!cgen()->allocator()->is_used(i));
       return RegisterAllocator::ToRegister(i);
     }
   }
   return no_reg;
 }
 
 
-// Make the type of the element at a given index be MEMORY.
-void VirtualFrame::SpillElementAt(int index) {
-  if (!elements_[index].is_valid()) return;
-
-  SyncElementAt(index);
-  // Number type information is preserved.
-  // Copies get their number information from their backing element.
-  NumberInfo info;
-  if (!elements_[index].is_copy()) {
-    info = elements_[index].number_info();
-  } else {
-    info = elements_[elements_[index].index()].number_info();
-  }
-  // The element is now in memory.  Its copied flag is preserved.
-  FrameElement new_element = FrameElement::MemoryElement(info);
-  if (elements_[index].is_copied()) {
-    new_element.set_copied();
-  }
-  if (elements_[index].is_untagged_int32()) {
-    new_element.set_untagged_int32(true);
-  }
-  if (elements_[index].is_register()) {
-    Unuse(elements_[index].reg());
-  }
-  elements_[index] = new_element;
-}
-
-
-// Clear the dirty bit for the element at a given index.
-void VirtualFrame::SyncElementAt(int index) {
-  if (index <= stack_pointer_) {
-    if (!elements_[index].is_synced()) SyncElementBelowStackPointer(index);
-  } else if (index == stack_pointer_ + 1) {
-    SyncElementByPushing(index);
-  } else {
-    SyncRange(stack_pointer_ + 1, index);
-  }
-}
-
-
-// Make the type of all elements be MEMORY.
-void VirtualFrame::SpillAll() {
-  for (int i = 0; i < element_count(); i++) {
-    SpillElementAt(i);
-  }
-}
-
-
-void VirtualFrame::PrepareMergeTo(VirtualFrame* expected) {
-  // Perform state changes on this frame that will make merge to the
-  // expected frame simpler or else increase the likelihood that his
-  // frame will match another.
-  for (int i = 0; i < element_count(); i++) {
-    FrameElement source = elements_[i];
-    FrameElement target = expected->elements_[i];
-
-    if (!target.is_valid() ||
-        (target.is_memory() && !source.is_memory() && source.is_synced())) {
-      // No code needs to be generated to invalidate valid elements.
-      // No code needs to be generated to move values to memory if
-      // they are already synced.  We perform those moves here, before
-      // merging.
-      if (source.is_register()) {
-        // If the frame is the code generator's current frame, we have
-        // to decrement both the frame-internal and global register
-        // counts.
-        if (cgen()->frame() == this) {
-          Unuse(source.reg());
-        } else {
-          set_register_location(source.reg(), kIllegalIndex);
-        }
-      }
-      elements_[i] = target;
-    } else if (target.is_register() && !target.is_synced() &&
-               !source.is_memory()) {
-      // If an element's target is a register that doesn't need to be
-      // synced, and the element is not in memory, then the sync state
-      // of the element is irrelevant.  We clear the sync bit.
-      ASSERT(source.is_valid());
-      elements_[i].clear_sync();
-    }
-  }
-}
-
-
-void VirtualFrame::PrepareForCall(int spilled_args, int dropped_args) {
-  ASSERT(height() >= dropped_args);
-  ASSERT(height() >= spilled_args);
-  ASSERT(dropped_args <= spilled_args);
-
-  SyncRange(0, element_count() - 1);
-  // Spill registers.
-  for (int i = 0; i < RegisterAllocator::kNumRegisters; i++) {
-    if (is_used(i)) {
-      SpillElementAt(register_location(i));
-    }
-  }
-
-  // Spill the arguments.
-  for (int i = element_count() - spilled_args; i < element_count(); i++) {
-    if (!elements_[i].is_memory()) {
-      SpillElementAt(i);
-    }
-  }
-
-  // Forget the frame elements that will be popped by the call.
-  Forget(dropped_args);
-}
-
-
-void VirtualFrame::PrepareForReturn() {
-  // Spill all locals. This is necessary to make sure all locals have
-  // the right value when breaking at the return site in the debugger.
-  for (int i = 0; i < expression_base_index(); i++) {
-    SpillElementAt(i);
-  }
-}
-
-
-void VirtualFrame::SetElementAt(int index, Result* value) {
-  int frame_index = element_count() - index - 1;
-  ASSERT(frame_index >= 0);
-  ASSERT(frame_index < element_count());
-  ASSERT(value->is_valid());
-  FrameElement original = elements_[frame_index];
-
-  // Early exit if the element is the same as the one being set.
-  bool same_register = original.is_register()
-      && value->is_register()
-      && original.reg().is(value->reg());
-  bool same_constant = original.is_constant()
-      && value->is_constant()
-      && original.handle().is_identical_to(value->handle());
-  if (same_register || same_constant) {
-    value->Unuse();
-    return;
-  }
-
-  InvalidateFrameSlotAt(frame_index);
-
-  if (value->is_register()) {
-    if (is_used(value->reg())) {
-      // The register already appears on the frame.  Either the existing
-      // register element, or the new element at frame_index, must be made
-      // a copy.
-      int i = register_location(value->reg());
-
-      if (i < frame_index) {
-        // The register FrameElement is lower in the frame than the new copy.
-        elements_[frame_index] = CopyElementAt(i);
-      } else {
-        // There was an early bailout for the case of setting a
-        // register element to itself.
-        ASSERT(i != frame_index);
-        elements_[frame_index] = elements_[i];
-        elements_[i] = CopyElementAt(frame_index);
-        if (elements_[frame_index].is_synced()) {
-          elements_[i].set_sync();
-        }
-        elements_[frame_index].clear_sync();
-        set_register_location(value->reg(), frame_index);
-        for (int j = i + 1; j < element_count(); j++) {
-          if (elements_[j].is_copy() && elements_[j].index() == i) {
-            elements_[j].set_index(frame_index);
-          }
-        }
-      }
-    } else {
-      // The register value->reg() was not already used on the frame.
-      Use(value->reg(), frame_index);
-      elements_[frame_index] =
-          FrameElement::RegisterElement(value->reg(),
-                                        FrameElement::NOT_SYNCED,
-                                        value->number_info());
-    }
-  } else {
-    ASSERT(value->is_constant());
-    elements_[frame_index] =
-        FrameElement::ConstantElement(value->handle(),
-                                      FrameElement::NOT_SYNCED);
-  }
-  value->Unuse();
-}
-
-
 // Specialization of List::ResizeAdd to non-inlined version for FrameElements.
 // The function ResizeAdd becomes a real function, whose implementation is the
 // inlined ResizeAddInternal.
 template <>
 void List<FrameElement,
           FreeStoreAllocationPolicy>::ResizeAdd(const FrameElement& element) {
   ResizeAddInternal(element);
 }
 
 } }  // namespace v8::internal