Add sk_float_rsqrt with SSE + NEON fast paths.

include/core/SkPoint.h

Index: include/core/SkPoint.h
diff --git a/include/core/SkPoint.h b/include/core/SkPoint.h
index b94f730ec2846056540bd657859826c8b3bb8f6d..caf26507ffa3c5e632ceb078a6a3301d0c08c5eb 100644
--- a/include/core/SkPoint.h
+++ b/include/core/SkPoint.h
@@ -216,13 +216,10 @@ struct SK_API SkPoint {
      *  Return true if the computed length of the vector is >= the internal
      *  tolerance (used to avoid dividing by tiny values).
      */
-    static bool CanNormalize(SkScalar dx, SkScalar dy)
-#ifdef SK_SCALAR_IS_FLOAT
-    // Simple enough (and performance critical sometimes) so we inline it.
-    { return (dx*dx + dy*dy) > (SK_ScalarNearlyZero * SK_ScalarNearlyZero); }
-#else
-    ;
-#endif
+    static bool CanNormalize(SkScalar dx, SkScalar dy) {
+        // Simple enough (and performance critical sometimes) so we inline it.
+        return (dx*dx + dy*dy) > (SK_ScalarNearlyZero * SK_ScalarNearlyZero);
+    }
 
     bool canNormalize() const {
         return CanNormalize(fX, fY);
@@ -252,6 +249,14 @@ struct SK_API SkPoint {
     */
     bool setLength(SkScalar x, SkScalar y, SkScalar length);
 
+    /** Same as setLength, but favoring speed over accuracy.
+    */
+    bool setLengthFast(SkScalar length);
+
+    /** Same as setLength, but favoring speed over accuracy.
+    */
+    bool setLengthFast(SkScalar x, SkScalar y, SkScalar length);
+
     /** Scale the point's coordinates by scale, writing the answer into dst.
         It is legal for dst == this.
     */
@@ -316,7 +321,6 @@ struct SK_API SkPoint {
      *  Returns true if both X and Y are finite (not infinity or NaN)
      */
     bool isFinite() const {
-#ifdef SK_SCALAR_IS_FLOAT
         SkScalar accum = 0;
         accum *= fX;
         accum *= fY;
@@ -327,12 +331,6 @@ struct SK_API SkPoint {
         // value==value will be true iff value is not NaN
         // TODO: is it faster to say !accum or accum==accum?
         return accum == accum;
-#else
-        // use bit-or for speed, since we don't care about short-circuting the
-        // tests, and we expect the common case will be that we need to check all.
-        int isNaN = (SK_FixedNaN == fX) | (SK_FixedNaN == fX));
-        return !isNaN;
-#endif
     }
 
     /**