limit number of searched roots

src/pathops/SkPathOpsCubic.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkGeometry.h"
 #include "SkLineParameters.h"
 #include "SkPathOpsConic.h"
 #include "SkPathOpsCubic.h"
@@ skipping 292 matching lines @@
     o1Pts[0] = &fPts[offset];
     o1Pts[1] = &fPts[++offset];
     o1Pts[2] = &fPts[++offset];
 }
 
 int SkDCubic::searchRoots(double extremeTs[6], int extrema, double axisIntercept,
         SearchAxis xAxis, double* validRoots) const {
     extrema += findInflections(&extremeTs[extrema]);
     extremeTs[extrema++] = 0;
     extremeTs[extrema] = 1;
+    SkASSERT(extrema < 6);
     SkTQSort(extremeTs, extremeTs + extrema);
     int validCount = 0;
     for (int index = 0; index < extrema; ) {
         double min = extremeTs[index];
         double max = extremeTs[++index];
         if (min == max) {
             continue;
         }
         double newT = binarySearch(min, max, axisIntercept, xAxis);
         if (newT >= 0) {
+            if (validCount >= 3) {
+                return 0;
+            }
             validRoots[validCount++] = newT;
         }
     }
     return validCount;
 }
 
 // cubic roots
 
 static const double PI = 3.141592653589793;
 
@@ skipping 357 matching lines @@
     for (int index = 0; index < roots; ++index) {
         double t = startT + (endT - startT) * extremeTs[index];
         SkDPoint mid = dCurve.ptAtT(t);
         if (topPt->fY > mid.fY || (topPt->fY == mid.fY && topPt->fX > mid.fX)) {
             topT = t;
             *topPt = mid;
         }
     }
     return topT;
 }