Switch from FloatMath -> Math and Math.hypot where possible

The motivation is an API change: FloatMath is going to be
deprecated and/or removed. Performance is not the goal of
this change.

That said...

Math is faster than FloatMath with AOT compilation.

While making the change, occurances of:

{Float}Math.sqrt(x * x + y * y) and
{Float}Math.sqrt({Float}Math.pow(x, 2) + {Float}Math.pow(y, 2))

have been replaced with:

{(float)} Math.hypot(x, y)

Right now there is no runtime intrinsic for hypot so is not faster
in all cases for AOT compilation:

Math.sqrt(x * x + y * y) is faster than Math.hypot(x, y) with
AOT, but all other combinations of FloatMath, use of pow() etc.
are slower than hypot().

hypot() has the advantage of being self documenting and
could be optimized in future. None of the behavior differences
around NaN and rounding appear to be important for the cases
looked at: they all assume results and arguments are in range
and usually the results are cast to float.

Different implementations measured on hammerhead / L:

AOT compiled:

[FloatMath.hypot(x, y)]
benchmark=Hypot_FloatMathHypot} 633.85 ns; σ=0.32 ns @ 3 trials

[FloatMath.sqrt(x*x + y*y)]
benchmark=Hypot_FloatMathSqrtMult} 684.17 ns; σ=4.83 ns @ 3 trials

[FloatMath.sqrt(FloatMath.pow(x, 2) + FloatMath.pow(y, 2))]
benchmark=Hypot_FloatMathSqrtPow} 1270.65 ns; σ=12.20 ns @ 6 trials

[(float) Math.hypot(x, y)]
benchmark=Hypot_MathHypot} 96.80 ns; σ=0.05 ns @ 3 trials

[(float) Math.sqrt(x*x + y*y)]
benchmark=Hypot_MathSqrtMult} 23.97 ns; σ=0.01 ns @ 3 trials

[(float) Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2))]
benchmark=Hypot_MathSqrtPow} 156.19 ns; σ=0.12 ns @ 3 trials

Interpreter:

benchmark=Hypot_FloatMathHypot} 1180.54 ns; σ=5.13 ns @ 3 trials
benchmark=Hypot_FloatMathSqrtMult} 1121.05 ns; σ=3.80 ns @ 3 trials
benchmark=Hypot_FloatMathSqrtPow} 3327.14 ns; σ=7.33 ns @ 3 trials
benchmark=Hypot_MathHypot} 856.57 ns; σ=1.41 ns @ 3 trials
benchmark=Hypot_MathSqrtMult} 1028.92 ns; σ=9.11 ns @ 3 trials
benchmark=Hypot_MathSqrtPow} 2539.47 ns; σ=24.44 ns @ 3 trials

Bug: https://code.google.com/p/android/issues/detail?id=36199
Change-Id: I06c91f682095e627cb547d60d936ef87941be692

3 files changed, 6 insertions, 10 deletions

diff --git a/graphics/java/android/graphics/ColorMatrix.java b/graphics/java/android/graphics/ColorMatrix.java
index e3596c8..0bfd07be 100644
--- a/graphics/java/android/graphics/ColorMatrix.java
+++ b/graphics/java/android/graphics/ColorMatrix.java
@@ -16,8 +16,6 @@
 
 package android.graphics;
 
-import android.util.FloatMath;
-
 /**
  *  4x5 matrix for transforming the color+alpha components of a Bitmap.
  *  The matrix is stored in a single array, and its treated as follows:
@@ -118,9 +116,9 @@ public class ColorMatrix {
      */
     public void setRotate(int axis, float degrees) {
         reset();
-        float radians = degrees * (float)Math.PI / 180;
-        float cosine = FloatMath.cos(radians);
-        float sine = FloatMath.sin(radians);
+        double radians = degrees * Math.PI / 180d;
+        float cosine = (float) Math.cos(radians);
+        float sine = (float) Math.sin(radians);
         switch (axis) {
         // Rotation around the red color
         case 0:
diff --git a/graphics/java/android/graphics/PointF.java b/graphics/java/android/graphics/PointF.java
index ee38dbb..8e4288e 100644
--- a/graphics/java/android/graphics/PointF.java
+++ b/graphics/java/android/graphics/PointF.java
@@ -18,7 +18,6 @@ package android.graphics;
 
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.util.FloatMath;
 
 
 /**
@@ -109,7 +108,7 @@ public class PointF implements Parcelable {
      * Returns the euclidian distance from (0,0) to (x,y)
      */
     public static float length(float x, float y) {
-        return FloatMath.sqrt(x * x + y * y);
+        return (float) Math.hypot(x, y);
     }
 
     /**
diff --git a/graphics/java/android/graphics/RectF.java b/graphics/java/android/graphics/RectF.java
index 53178b0..f5cedfa 100644
--- a/graphics/java/android/graphics/RectF.java
+++ b/graphics/java/android/graphics/RectF.java
@@ -20,7 +20,6 @@ import java.io.PrintWriter;
 
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.util.FloatMath;
 import com.android.internal.util.FastMath;
 
 /**
@@ -450,8 +449,8 @@ public class RectF implements Parcelable {
      * floor of top and left, and the ceiling of right and bottom.
      */
     public void roundOut(Rect dst) {
-        dst.set((int) FloatMath.floor(left), (int) FloatMath.floor(top),
-                (int) FloatMath.ceil(right), (int) FloatMath.ceil(bottom));
+        dst.set((int) Math.floor(left), (int) Math.floor(top),
+                (int) Math.ceil(right), (int) Math.ceil(bottom));
     }
 
     /**