Shrink SVG paint-order to take less bits

Source/core/style/SVGComputedStyle.cpp

Index: Source/core/style/SVGComputedStyle.cpp
diff --git a/Source/core/style/SVGComputedStyle.cpp b/Source/core/style/SVGComputedStyle.cpp
index 36b237672bf134d7b8ec97ba5448eca2edf3e5b1..14e437c5d0f911bd158d5fe39e99fc02da0f5dbe 100644
--- a/Source/core/style/SVGComputedStyle.cpp
+++ b/Source/core/style/SVGComputedStyle.cpp
@@ -236,7 +236,7 @@ bool SVGComputedStyle::diffNeedsPaintInvalidation(const SVGComputedStyle* other)
         || svg_inherited_flags._fillRule != other->svg_inherited_flags._fillRule
         || svg_inherited_flags._colorInterpolation != other->svg_inherited_flags._colorInterpolation
         || svg_inherited_flags._colorInterpolationFilters != other->svg_inherited_flags._colorInterpolationFilters
-        || svg_inherited_flags._paintOrder != other->svg_inherited_flags._paintOrder)
+        || svg_inherited_flags.paintOrder != other->svg_inherited_flags.paintOrder)
         return true;
 
     if (svg_noninherited_flags.f.bufferedRendering != other->svg_noninherited_flags.f.bufferedRendering)
@@ -250,8 +250,32 @@ bool SVGComputedStyle::diffNeedsPaintInvalidation(const SVGComputedStyle* other)
 
 EPaintOrderType SVGComputedStyle::paintOrderType(unsigned index) const
 {
+    const int kPaintOrderBitwidth = 2;
+    unsigned pt = 0;
     ASSERT(index < ((1 << kPaintOrderBitwidth)-1));
-    unsigned pt = (paintOrder() >> (kPaintOrderBitwidth*index)) & ((1u << kPaintOrderBitwidth) - 1);
+    switch (this->paintOrder()) {
+    case PaintOrderNormal:
+    case PaintOrderFillStrokeMarkers:
+        pt = (((PT_MARKERS << kPaintOrderBitwidth) | PT_STROKE) << kPaintOrderBitwidth) | PT_FILL;

[fs, 2015/07/30 14:39:37]

This doesn't read very well IMO, either a helper:

unsigned paintOrderSequence(... first, ... second, ... third)
{
    // pack somehow
}
...
pt = paintOrderSequence(PT_FILL, PT_STROKE, PT_MARKERS);

or data-driven:

static const unsigned paintOrderSequence[] = {
    <packing helper>,
    ...
};
unsigned pt = paintOrderSequence[paintOrder()];

Hopefully the generated code is similar though. Making for lower visibility of
kPaintOrderBitwidth and make the sequence read in the "right" order would be the
goal IMO.

[Shanmuga Pandi, 2015/07/31 08:44:50]

Done.

+        break;
+    case PaintOrderFillMarkersStroke:
+        pt = (((PT_STROKE << kPaintOrderBitwidth) | PT_MARKERS) << kPaintOrderBitwidth) | PT_FILL;
+        break;
+    case PaintOrderStrokeFillMarkers:
+        pt = (((PT_MARKERS << kPaintOrderBitwidth) | PT_FILL) << kPaintOrderBitwidth) | PT_STROKE;
+        break;
+    case PaintOrderStrokeMarkersFill:
+        pt = (((PT_FILL << kPaintOrderBitwidth) | PT_MARKERS) << kPaintOrderBitwidth) | PT_STROKE;
+        break;
+    case PaintOrderMarkersFillStroke:
+        pt = (((PT_STROKE << kPaintOrderBitwidth) | PT_FILL) << kPaintOrderBitwidth) | PT_MARKERS;
+        break;
+    case PaintOrderMarkersStrokeFill:
+        pt = (((PT_FILL << kPaintOrderBitwidth) | PT_STROKE) << kPaintOrderBitwidth) | PT_MARKERS;
+        break;
+    }
+
+    pt = (pt >> (kPaintOrderBitwidth*index)) & ((1u << kPaintOrderBitwidth) - 1);
     return (EPaintOrderType)pt;
 }