Enable subsequence caching for spv2

third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/graphics/paint/PaintArtifact.h"
 
 #include "platform/TraceEvent.h"
 #include "platform/geometry/IntRect.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/graphics/paint/DrawingDisplayItem.h"
@@ skipping 59 matching lines @@
 }
 
 PaintArtifact& PaintArtifact::operator=(PaintArtifact&& source)
 {
     m_displayItemList = std::move(source.m_displayItemList);
     m_paintChunks = std::move(source.m_paintChunks);
     m_isSuitableForGpuRasterization = source.m_isSuitableForGpuRasterization;
     return *this;
 }
 
+static bool compareChunkAndIndex(const PaintChunk& chunk, unsigned index)

[pdr., 2016/07/26 16:54:21]

Should all of these unsigned be size_t (here, and in PaintChunk)?

[Xianzhu, 2016/07/26 17:01:43]

Do you know what was the reason that we chose unsigned in PaintChunk? One reason
I guess is to limit size of chunks on 64-bit systems. Wdyt?

+{
+    return chunk.endIndex <= index;
+}
+
+Vector<PaintChunk>::const_iterator PaintArtifact::findChunkByDisplayItemIndex(unsigned index) const
+{
+    auto chunkIt = std::lower_bound(m_paintChunks.begin(), m_paintChunks.end(), index, compareChunkAndIndex);
+    DCHECK(chunkIt != m_paintChunks.end());
+    DCHECK(index >= chunkIt->beginIndex);
+    DCHECK(index < chunkIt->endIndex);
+    return chunkIt;
+}
+
 void PaintArtifact::reset()
 {
     m_displayItemList.clear();
     m_paintChunks.clear();
 }
 
 size_t PaintArtifact::approximateUnsharedMemoryUsage() const
 {
     return sizeof(*this) + m_displayItemList.memoryUsageInBytes()
         + m_paintChunks.capacity() * sizeof(m_paintChunks[0]);
@@ skipping 11 matching lines @@
     TRACE_EVENT0("blink,benchmark", "PaintArtifact::appendToWebDisplayItemList");
     unsigned visualRectIndex = 0;
     for (const DisplayItem& displayItem : m_displayItemList) {
         displayItem.appendToWebDisplayItemList(m_displayItemList.visualRect(visualRectIndex), list);
         visualRectIndex++;
     }
     list->setIsSuitableForGpuRasterization(isSuitableForGpuRasterization());
 }
 
 } // namespace blink