| // 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 |
| // with the distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #include "v8.h" |
| |
| #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_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 |