Explicitly check edge count >= 2 in non-debug build

We also preserve the check in debug mode that the
count should never be 1 when the path is convex.

Bug: skia:6684
Change-Id: I4d4c9ad9f9d704e94bbe51f10a96f8b3066afaa1
Reviewed-on: https://skia-review.googlesource.com/17983
Commit-Queue: Yuqian Li <liyuqian@google.com>
Reviewed-by: Mike Reed <reed@google.com>

4 files changed, 27 insertions, 25 deletions

diff --git a/src/core/SkEdgeBuilder.cpp b/src/core/SkEdgeBuilder.cpp
index f1aa105ec8..385193040b 100644
--- a/src/core/SkEdgeBuilder.cpp
+++ b/src/core/SkEdgeBuilder.cpp
@@ -441,3 +441,18 @@ int SkEdgeBuilder::build(const SkPath& path, const SkIRect* iclip, int shiftUp,
     fEdgeList = fList.begin();
     return fList.count();
 }
+
+int SkEdgeBuilder::build_edges(const SkPath& path, const SkIRect* shiftedClip,
+        int shiftEdgesUp, bool pathContainedInClip, bool analyticAA) {
+    // If we're convex, then we need both edges, even the right edge is past the clip
+    const bool canCullToTheRight = !path.isConvex();
+
+    const SkIRect* builderClip = pathContainedInClip ? nullptr : shiftedClip;
+    int count = this->build(path, builderClip, shiftEdgesUp, canCullToTheRight, analyticAA);
+    SkASSERT(count >= 0);
+
+    // canCullToRight == false should imply count != 1
+    SkASSERT(canCullToTheRight || count != 1);
+
+    return count;
+}
diff --git a/src/core/SkEdgeBuilder.h b/src/core/SkEdgeBuilder.h
index 8d38f10466..2f2b35104f 100644
--- a/src/core/SkEdgeBuilder.h
+++ b/src/core/SkEdgeBuilder.h
@@ -25,6 +25,9 @@ public:
     int build(const SkPath& path, const SkIRect* clip, int shiftUp, bool clipToTheRight,
               bool analyticAA = false);
 
+    int build_edges(const SkPath& path, const SkIRect* shiftedClip,
+            int shiftEdgesUp, bool pathContainedInClip, bool analyticAA = false);
+
     SkEdge** edgeList() { return (SkEdge**)fEdgeList; }
     SkAnalyticEdge** analyticEdgeList() { return (SkAnalyticEdge**)fEdgeList; }
 
diff --git a/src/core/SkScan_AAAPath.cpp b/src/core/SkScan_AAAPath.cpp
index 3eca137642..cb38d6131a 100644
--- a/src/core/SkScan_AAAPath.cpp
+++ b/src/core/SkScan_AAAPath.cpp
@@ -1592,17 +1592,9 @@ static SK_ALWAYS_INLINE void aaa_fill_path(const SkPath& path, const SkIRect& cl
         bool isUsingMask, bool forceRLE) { // forceRLE implies that SkAAClip is calling us
     SkASSERT(blitter);
 
-    SkEdgeBuilder   builder;
-
-    // If we're convex, then we need both edges, even the right edge is past the clip
-    const bool canCullToTheRight = !path.isConvex();
-
-    SkASSERT(gSkUseAnalyticAA.load());
-    const SkIRect* builderClip = pathContainedInClip ? nullptr : &clipRect;
-    int count = builder.build(path, builderClip, 0, canCullToTheRight, true);
-    SkASSERT(count >= 0);
-
-    SkAnalyticEdge** list = (SkAnalyticEdge**)builder.analyticEdgeList();
+    SkEdgeBuilder builder;
+    int count = builder.build_edges(path, &clipRect, 0, pathContainedInClip, true);
+    SkAnalyticEdge** list = builder.analyticEdgeList();
 
     SkIRect rect = clipRect;
     if (0 == count) {
@@ -1671,8 +1663,7 @@ static SK_ALWAYS_INLINE void aaa_fill_path(const SkPath& path, const SkIRect& cl
         rightBound = SkTMin(rightBound, SkIntToFixed(ir.fRight));
     }
 
-    if (!path.isInverseFillType() && path.isConvex()) {
-        SkASSERT(count >= 2);   // convex walker does not handle missing right edges
+    if (!path.isInverseFillType() && path.isConvex() && count >= 2) {
         aaa_walk_convex_edges(&headEdge, blitter, start_y, stop_y,
                               leftBound, rightBound, isUsingMask);
     } else {
diff --git a/src/core/SkScan_Path.cpp b/src/core/SkScan_Path.cpp
index 0415b2f99a..0975af8ddc 100644
--- a/src/core/SkScan_Path.cpp
+++ b/src/core/SkScan_Path.cpp
@@ -396,16 +396,9 @@ void sk_fill_path(const SkPath& path, const SkIRect& clipRect, SkBlitter* blitte
     shiftedClip.fTop <<= shiftEdgesUp;
     shiftedClip.fBottom <<= shiftEdgesUp;
 
-    SkEdgeBuilder   builder;
-
-    // If we're convex, then we need both edges, even the right edge is past the clip
-    const bool canCullToTheRight = !path.isConvex();
-
-    SkIRect* builderClip = pathContainedInClip ? nullptr : &shiftedClip;
-    int count = builder.build(path, builderClip, shiftEdgesUp, canCullToTheRight);
-    SkASSERT(count >= 0);
-
-    SkEdge**    list = builder.edgeList();
+    SkEdgeBuilder builder;
+    int count = builder.build_edges(path, &shiftedClip, shiftEdgesUp, pathContainedInClip);
+    SkEdge** list = builder.edgeList();
 
     if (0 == count) {
         if (path.isInverseFillType()) {
@@ -467,8 +460,8 @@ void sk_fill_path(const SkPath& path, const SkIRect& clipRect, SkBlitter* blitte
         proc = PrePostInverseBlitterProc;
     }
 
-    if (path.isConvex() && (nullptr == proc)) {
-        SkASSERT(count >= 2);   // convex walker does not handle missing right edges
+    // count >= 2 is required as the convex walker does not handle missing right edges
+    if (path.isConvex() && (nullptr == proc) && count >= 2) {
         walk_convex_edges(&headEdge, path.getFillType(), blitter, start_y, stop_y, nullptr);
     } else {
         walk_edges(&headEdge, path.getFillType(), blitter, start_y, stop_y, proc,