ios fixes

src/core/SkPoint.cpp

 
 /*
  * Copyright 2008 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkPoint.h"
@@ skipping 150 matching lines @@
 
     float scale;
     if (SkScalarIsFinite(mag2)) {
         scale = length / sk_float_sqrt(mag2);
     } else {
         // our mag2 step overflowed to infinity, so use doubles instead.
         // much slower, but needed when x or y are very large, other wise we
         // divide by inf. and return (0,0) vector.
         double xx = x;
         double yy = y;
+    #ifdef SK_FAST_UNDERFLOW_BEHAVIOR
+        // The iOS ARM processor discards small denormalized numbers to go faster.

[reed1, 2014/07/10 21:40:05]

I think this comment belongs in SkMathPriv.h or whereever we define this symbol.

That said, I know you took my suggested name, but seeing it now I'm not sure its
a good encapsulation of the behavior/difference, but I'll leave that to you.

[caryclark, 2014/07/11 12:57:19]

Done.

+        // Casting this to a float would cause the scale to go to zero. Keeping it
+        // as a double for the multipy keeps the scale non-zero.
+        double dscale = length / sqrt(xx * xx + yy * yy);
+        fX = x * dscale;
+        fY = y * dscale;
+        return true;
+    #else
         scale = (float)(length / sqrt(xx * xx + yy * yy));
+    #endif
     }
     fX = x * scale;
     fY = y * scale;
     return true;
 }
 
 bool SkPoint::setLengthFast(float length) {
     return this->setLengthFast(fX, fY, length);
 }
 
@@ skipping 66 matching lines @@
 
     if (uDotV <= 0) {
         return v.lengthSqd();
     } else if (uDotV > uLengthSqd) {
         return b.distanceToSqd(*this);
     } else {
         SkScalar det = u.cross(v);
         return SkScalarMulDiv(det, det, uLengthSqd);
     }
 }