Set SkDAARecord to empty type if the scan converter returns early

Otherwise,

	./out/Debug/dm --config t8888 -m bug583299

will crash at SkASSERT(record->fType != SkDAARecord::Type::kToBeComputed)

Bug: skia:
Change-Id: Ie93221bd6ea7ab9bc9f3d79fd7fe02b315e6a089
Reviewed-on: https://skia-review.googlesource.com/111680
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Yuqian Li <liyuqian@google.com>

src/core/SkCoverageDelta.h

@@ -186,7 +186,8 @@ struct SkDAARecord {
     enum class Type {
         kToBeComputed,
         kMask,
-        kList
+        kList,
+        kEmpty
     } fType;
 
     SkMask               fMask;
@@ -194,6 +195,19 @@ struct SkDAARecord {
     SkArenaAlloc*        fAlloc;
 
     SkDAARecord(SkArenaAlloc* alloc) : fType(Type::kToBeComputed), fAlloc(alloc) {}
+
+    // When the scan converter returns early (e.g., the path is completely out of the clip), we set
+    // the type to empty to signal that the record has been computed and it's empty. This is
+    // required only for DEBUG where we check that the type must not be kToBeComputed after
+    // init-once.
+    void setEmpty() { fType = Type::kEmpty; }
+    static inline void SetEmpty(SkDAARecord* record) { // record may be nullptr
+#ifdef SK_DEBUG
+        if (record) {
+            record->setEmpty();
+        }
+#endif
+    }
 };
 
 template<typename T>

src/core/SkScan_AntiPath.cpp

@@ -669,6 +669,7 @@ static SkIRect safeRoundOut(const SkRect& src) {
 void SkScan::AntiFillPath(const SkPath& path, const SkRegion& origClip,
                           SkBlitter* blitter, bool forceRLE, SkDAARecord* daaRecord) {
     if (origClip.isEmpty()) {
+        SkDAARecord::SetEmpty(daaRecord);
         return;
     }
 
@@ -678,6 +679,7 @@ void SkScan::AntiFillPath(const SkPath& path, const SkRegion& origClip,
         if (isInverse) {
             blitter->blitRegion(origClip);
         }
+        SkDAARecord::SetEmpty(daaRecord);
         return;
     }
 
@@ -691,10 +693,11 @@ void SkScan::AntiFillPath(const SkPath& path, const SkRegion& origClip,
        clippedIR = origClip.getBounds();
     } else {
        if (!clippedIR.intersect(ir, origClip.getBounds())) {
+            SkDAARecord::SetEmpty(daaRecord);
            return;
        }
     }
-    if (rect_overflows_short_shift(clippedIR, SHIFT)) {
+    if (!daaRecord && rect_overflows_short_shift(clippedIR, SHIFT)) {
         SkScan::FillPath(path, origClip, blitter);
         return;
     }
@@ -724,6 +727,7 @@ void SkScan::AntiFillPath(const SkPath& path, const SkRegion& origClip,
         if (isInverse) {
             blitter->blitRegion(*clipRgn);
         }
+        SkDAARecord::SetEmpty(daaRecord);
         return;
     }
 
@@ -776,6 +780,7 @@ void SkScan::FillPath(const SkPath& path, const SkRasterClip& clip, SkBlitter* b
 void SkScan::AntiFillPath(const SkPath& path, const SkRasterClip& clip,
                           SkBlitter* blitter, SkDAARecord* daaRecord) {
     if (clip.isEmpty() || !path.isFinite()) {
+        SkDAARecord::SetEmpty(daaRecord);
         return;
     }
 

src/core/SkScan_DAAPath.cpp

@@ -330,6 +330,7 @@ void SkScan::DAAFillPath(const SkPath& path, SkBlitter* blitter, const SkIRect&
     // The overhead of even constructing SkCoverageDeltaList/Mask is too big.
     // So TryBlitFatAntiRect and return if it's successful.
     if (!isInverse && TryBlitFatAntiRect(blitter, path, clipBounds)) {
+        SkDAARecord::SetEmpty(record);
         return;
     }