give up if huge paths have unresolvable coincidence

src/pathops/SkOpCoincidence.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkOpCoincidence.h"
 #include "SkOpSegment.h"
 #include "SkPathOpsTSect.h"
 
@@ skipping 616 matching lines @@
             if (coin->fOppPtTStart->span() == kept->span()) {
                 this->release(coin);
                 continue;
             }
             coin->fOppPtTEnd = kept;
         }
     } while ((coin = coin->fNext));
 }
 
 /* this sets up the coincidence links in the segments when the coincidence crosses multiple spans */
-void SkOpCoincidence::mark() {
+bool SkOpCoincidence::mark() {
     SkCoincidentSpans* coin = fHead;
     if (!coin) {
-        return;
+        return true;
     }
     do {
         SkOpSpanBase* end = coin->fCoinPtTEnd->span();
+        if (end->deleted()) {
+          return false;
+        }
         SkOpSpanBase* oldEnd = end;
         SkOpSpan* start = coin->fCoinPtTStart->span()->starter(&end);
         SkOpSpanBase* oEnd = coin->fOppPtTEnd->span();
+        if (oEnd->deleted()) {
+          return false;
+        }
         SkOpSpanBase* oOldEnd = oEnd;
         SkOpSpanBase* oStart = coin->fOppPtTStart->span()->starter(&oEnd);
         bool flipped = (end == oldEnd) != (oEnd == oOldEnd);
         if (flipped) {
             SkTSwap(oStart, oEnd);
         }
         SkOpSpanBase* next = start;
         SkOpSpanBase* oNext = oStart;
         do {
             next = next->upCast()->next();
             oNext = flipped ? oNext->prev() : oNext->upCast()->next();
             if (next == end || oNext == oEnd) {
                 break;
             }
             if (!next->containsCoinEnd(oNext)) {
                 next->insertCoinEnd(oNext);
             }
             SkOpSpan* nextSpan = next->upCast();
             SkOpSpan* oNextSpan = oNext->upCast();
             if (!nextSpan->containsCoincidence(oNextSpan)) {
                 nextSpan->insertCoincidence(oNextSpan);
             }
         } while (true);
     } while ((coin = coin->fNext));
+    return true;
 }
 
 bool SkOpCoincidence::overlap(const SkOpPtT* coin1s, const SkOpPtT* coin1e, 
         const SkOpPtT* coin2s, const SkOpPtT* coin2e, double* overS, double* overE) const {
     SkASSERT(coin1s->segment() == coin2s->segment());
     *overS = SkTMax(SkTMin(coin1s->fT, coin1e->fT), SkTMin(coin2s->fT, coin2e->fT));
     *overE = SkTMin(SkTMax(coin1s->fT, coin1e->fT), SkTMax(coin2s->fT, coin2e->fT));
     return *overS < *overE;
 }
 
 bool SkOpCoincidence::testForCoincidence(const SkCoincidentSpans* outer, const SkOpPtT* testS,
         const SkOpPtT* testE) const {
     return testS->segment()->testForCoincidence(testS, testE, testS->span(),
             testE->span(), outer->fCoinPtTStart->segment(), 120000);  // FIXME: replace with tuned
 }