Add sqrt() and rsqrt() to Sk4f.

src/core/Sk4x_portable.h

 // It is important _not_ to put header guards here.
 // This file will be intentionally included three times.
 
 #if defined(SK4X_PREAMBLE)
+    #include "SkFloatingPoint.h"
+    #include <math.h>
 
 #elif defined(SK4X_PRIVATE)
     typedef T Type;
     typedef T Vector[4];
 
     Vector fVec;
 
     template <int m, int a, int s, int k>
     static Sk4x Shuffle(const Sk4x&, const Sk4x&);
 
@@ skipping 38 matching lines @@
                   fVec[2] op other.fVec[2], \
                   fVec[3] op other.fVec[3]
 M(Sk4x<T>)   bitAnd(const Sk4x& other)    const { return Sk4x(BINOP(&)); }
 M(Sk4x<T>)    bitOr(const Sk4x& other)    const { return Sk4x(BINOP(|)); }
 M(Sk4x<T>)      add(const Sk4x<T>& other) const { return Sk4x(BINOP(+)); }
 M(Sk4x<T>) subtract(const Sk4x<T>& other) const { return Sk4x(BINOP(-)); }
 M(Sk4x<T>) multiply(const Sk4x<T>& other) const { return Sk4x(BINOP(*)); }
 M(Sk4x<T>)   divide(const Sk4x<T>& other) const { return Sk4x(BINOP(/)); }
 #undef BINOP
 
+template<> inline Sk4f Sk4f::rsqrt() const {
+    return Sk4f(sk_float_rsqrt(fVec[0]),
+                sk_float_rsqrt(fVec[1]),
+                sk_float_rsqrt(fVec[2]),
+                sk_float_rsqrt(fVec[3]));
+}
+
+template<> inline Sk4f Sk4f::sqrt() const {
+    return Sk4f(sqrtf(fVec[0]),
+                sqrtf(fVec[1]),
+                sqrtf(fVec[2]),
+                sqrtf(fVec[3]));
+}
+
 #define BOOL_BINOP(op) fVec[0] op other.fVec[0] ? -1 : 0, \
                        fVec[1] op other.fVec[1] ? -1 : 0, \
                        fVec[2] op other.fVec[2] ? -1 : 0, \
                        fVec[3] op other.fVec[3] ? -1 : 0
 M(Sk4i)            equal(const Sk4x<T>& other) const { return Sk4i(BOOL_BINOP(==)); }
 M(Sk4i)         notEqual(const Sk4x<T>& other) const { return Sk4i(BOOL_BINOP(!=)); }
 M(Sk4i)         lessThan(const Sk4x<T>& other) const { return Sk4i(BOOL_BINOP( <)); }
 M(Sk4i)      greaterThan(const Sk4x<T>& other) const { return Sk4i(BOOL_BINOP( >)); }
 M(Sk4i)    lessThanEqual(const Sk4x<T>& other) const { return Sk4i(BOOL_BINOP(<=)); }
 M(Sk4i) greaterThanEqual(const Sk4x<T>& other) const { return Sk4i(BOOL_BINOP(>=)); }
@@ skipping 20 matching lines @@
                 k < 4 ? x.fVec[k] : y.fVec[k-4]);
 }
 
 M(Sk4x<T>) zwxy() const                             { return Shuffle<2,3,0,1>(*this, *this); }
 M(Sk4x<T>) XYAB(const Sk4x& xyzw, const Sk4x& abcd) { return Shuffle<0,1,4,5>( xyzw,  abcd); }
 M(Sk4x<T>) ZWCD(const Sk4x& xyzw, const Sk4x& abcd) { return Shuffle<2,3,6,7>( xyzw,  abcd); }
 
 #undef M
 
 #endif