Issue trace events to gather repaint information.

Source/core/rendering/RenderObject.cpp

Index: Source/core/rendering/RenderObject.cpp
diff --git a/Source/core/rendering/RenderObject.cpp b/Source/core/rendering/RenderObject.cpp
index d55645e614dfe44aece0455d296605469d0c60a7..60d0788319b45a749c4d07739310f7925c2623c9 100644
--- a/Source/core/rendering/RenderObject.cpp
+++ b/Source/core/rendering/RenderObject.cpp
@@ -82,6 +82,7 @@
 #include "platform/graphics/GraphicsContext.h"
 #include "wtf/RefCountedLeakCounter.h"
 #include "wtf/text/StringBuilder.h"
+#include "wtf/text/WTFString.h"
 #include <algorithm>
 #ifndef NDEBUG
 #include <stdio.h>
@@ -1367,6 +1368,10 @@ RenderLayerModelObject* RenderObject::containerForRepaint() const
 
 void RenderObject::repaintUsingContainer(const RenderLayerModelObject* repaintContainer, const IntRect& r) const
 {
+    TRACE_EVENT2(TRACE_DISABLED_BY_DEFAULT("blink.invalidation"), "RenderObject::repaintUsingContainer()",
+        "object", TRACE_STR_COPY(this->debugName().ascii().data()),
+        "rect", TRACE_STR_COPY(String::format("%d,%d %dx%d", r.x(), r.y(), r.width(), r.height()).ascii().data()));
+
     if (!repaintContainer) {
         view()->repaintViewRectangle(r);
         return;
@@ -1439,6 +1444,9 @@ void RenderObject::repaint() const
     if (view->document().printing())
         return; // Don't repaint if we're printing.
 
+    TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("blink.invalidation"), "RenderObject::repaint()",
+        "object", TRACE_STR_COPY(this->debugName().ascii().data()));
+
     // FIXME: really, we're in the repaint phase here, and the following queries are legal.
     // Until those states are fully fledged, I'll just disable the ASSERTS.
     DisableCompositingQueryAsserts disabler;
@@ -1456,6 +1464,9 @@ void RenderObject::repaintRectangle(const LayoutRect& r) const
     if (view->document().printing())
         return; // Don't repaint if we're printing.
 
+    TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("blink.invalidation"), "RenderObject::repaintRectangle()",
+        "object", TRACE_STR_COPY(this->debugName().ascii().data()));
+
     LayoutRect dirtyRect(r);
 
     if (!RuntimeEnabledFeatures::repaintAfterLayoutEnabled()) {
@@ -1474,6 +1485,26 @@ IntRect RenderObject::pixelSnappedAbsoluteClippedOverflowRect() const
     return pixelSnappedIntRect(absoluteClippedOverflowRect());
 }
 
+const char* RenderObject::invalidationReasonToString(const InvalidationReason reason) const
+{
+    switch (reason) {
+    case InvalidationIncremental:
+        return "incremental";
+    case InvalidationSelfLayout:
+        return "self layout";
+    case InvalidationBorderFitLines:
+        return "border fit lines";
+    case InvalidationBorderRadius:
+        return "border radius";
+    case InvalidationBoundsChangeWithBackground:
+        return "bounds change with background";
+    case InvalidationBoundsChange:
+        return "bounds change";
+    default:
+        return "unknown";

[Julien - ping for review, 2014/03/31 18:26:45]

ASSERT_NOT_REACHED()?

[dsinclair, 2014/03/31 19:24:34]

Done.

+    }
+}
+
 bool RenderObject::repaintAfterLayoutIfNeeded(const RenderLayerModelObject* repaintContainer, bool wasSelfLayout,
     const LayoutRect& oldBounds, const LayoutRect* newBoundsPtr)
 {
@@ -1481,34 +1512,46 @@ bool RenderObject::repaintAfterLayoutIfNeeded(const RenderLayerModelObject* repa
     if (v->document().printing())
         return false; // Don't repaint if we're printing.
 
+    TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("blink.invalidation"), "RenderObject::repaintAfterLayoutIfNeeded",
+        "object", TRACE_STR_COPY(this->debugName().ascii().data()));
+
     // This ASSERT fails due to animations.  See https://bugs.webkit.org/show_bug.cgi?id=37048
     // ASSERT(!newBoundsPtr || *newBoundsPtr == clippedOverflowRectForRepaint(repaintContainer));
     LayoutRect newBounds = newBoundsPtr ? *newBoundsPtr : clippedOverflowRectForRepaint(repaintContainer);
 
-    bool fullRepaint = wasSelfLayout;
+    InvalidationReason invalidationReason = InvalidationIncremental;
+    if (wasSelfLayout)
+        invalidationReason = InvalidationSelfLayout;

[Julien - ping for review, 2014/03/31 18:26:45]

We should just use the ternary operator ? here as it would make the code more
compact.

[dsinclair, 2014/03/31 19:24:34]

Done.

+
     // Presumably a background or a border exists if border-fit:lines was specified.
-    if (!fullRepaint && style()->borderFit() == BorderFitLines)
-        fullRepaint = true;
-    if (!fullRepaint && style()->hasBorderRadius()) {
+    if (invalidationReason == InvalidationIncremental && style()->borderFit() == BorderFitLines)
+        invalidationReason = InvalidationBorderFitLines;
+
+    if (invalidationReason == InvalidationIncremental&& style()->hasBorderRadius()) {
         // If a border-radius exists and width/height is smaller than
         // radius width/height, we cannot use delta-repaint.
         RoundedRect oldRoundedRect = style()->getRoundedBorderFor(oldBounds);
         RoundedRect newRoundedRect = style()->getRoundedBorderFor(newBounds);
-        fullRepaint = oldRoundedRect.radii() != newRoundedRect.radii();
+        if (oldRoundedRect.radii() != newRoundedRect.radii())
+            invalidationReason = InvalidationBorderRadius;
     }
 
-    if (!fullRepaint && (mustRepaintBackgroundOrBorder() && (newBounds != oldBounds)))
-        fullRepaint = true;
+    if (invalidationReason == InvalidationIncremental && (mustRepaintBackgroundOrBorder() && (newBounds != oldBounds)))
+        invalidationReason = InvalidationBoundsChangeWithBackground;
 
     // If we shifted, we don't know the exact reason so we are conservative and trigger a full invalidation. Shifting could
     // be caused by some layout property (left / top) or some in-flow renderer inserted / removed before us in the tree.
-    if (!fullRepaint && newBounds.location() != oldBounds.location())
-        fullRepaint = true;
+    if (invalidationReason == InvalidationIncremental && newBounds.location() != oldBounds.location())
+        invalidationReason = InvalidationBoundsChange;
 
     if (!repaintContainer)
         repaintContainer = v;
 
-    if (fullRepaint) {
+    if (invalidationReason != InvalidationIncremental) {
+        TRACE_EVENT_INSTANT2(TRACE_DISABLED_BY_DEFAULT("blink.invalidation"), "invalidation_reason",
+            "object", TRACE_STR_COPY(this->debugName().ascii().data()),
+            "reason", invalidationReasonToString(invalidationReason));

[Julien - ping for review, 2014/03/31 18:26:45]

Why don't we just pass the invalidation reason to repaintUsingContainer? That
would avoid these lines and remove some code duplication / duplicated traces.

[dsinclair, 2014/03/31 19:24:34]

Done.

+
         repaintUsingContainer(repaintContainer, pixelSnappedIntRect(oldBounds));
         if (newBounds != oldBounds)
             repaintUsingContainer(repaintContainer, pixelSnappedIntRect(newBounds));
@@ -1518,6 +1561,10 @@ bool RenderObject::repaintAfterLayoutIfNeeded(const RenderLayerModelObject* repa
     if (oldBounds == newBounds)
         return false;
 
+    TRACE_EVENT_INSTANT2(TRACE_DISABLED_BY_DEFAULT("blink.invalidation"), "invalidation_reason",
+        "object", TRACE_STR_COPY(this->debugName().ascii().data()),
+        "reason", invalidationReasonToString(invalidationReason));
+
     LayoutUnit deltaLeft = newBounds.x() - oldBounds.x();
     if (deltaLeft > 0)
         repaintUsingContainer(repaintContainer, pixelSnappedIntRect(oldBounds.x(), oldBounds.y(), deltaLeft, oldBounds.height()));