From 32b88b48daa7383880088246d7222dd93cf55285 Mon Sep 17 00:00:00 2001 From: Neil Fuller Date: Mon, 29 Sep 2014 17:56:01 +0100 Subject: Replacing FloatMath native implementation with calls to Math On modern versions of Android running in AOT mode FloatMath is slower than Math. Calls to Math.sqrt(), etc. are replaced by intrinsics which can be as small as a single CPU opcode. When running in interpreted mode the new implementation is unfortunately slower, but I'm judging this acceptable and likely to be improved over time. This change saves a small amount of native code. Example timings: Mako AOSP AOT: Method: Original / New / Direct call to Math ceil: 596ns / 146.ns / 111ns sqrt: 694ns / 56ns / 25ns Mako AOSP interpreted: Method: Original / New / Direct call to Math ceil: 1900ns / 2307ns / 1485ns sqrt: 1998ns / 2603ns / 1788ns Other calls Mako AOT: Method: Original / New cos: 635ns / 270ns exp: 566ns / 324ns floor: 604ns / 150ns hypot: 631ns / 232ns pow: 936ns / 643ns sin: 641ns / 299ns The advice to use Math directly, in preference to FloatMath, is still good. FloatMath will be deprecated separately. Bug: https://code.google.com/p/android/issues/detail?id=36199 Change-Id: I8d1947d88b3c576643138b1df589fb9da7c1ab88 --- core/java/android/util/FloatMath.java | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'core/java/android/util') diff --git a/core/java/android/util/FloatMath.java b/core/java/android/util/FloatMath.java index 0ffd5bd..d33ca0d 100644 --- a/core/java/android/util/FloatMath.java +++ b/core/java/android/util/FloatMath.java @@ -17,10 +17,13 @@ package android.util; /** - * Math routines similar to those found in {@link java.lang.Math}. On - * versions of Android with a JIT, these are significantly slower than - * the equivalent {@code Math} functions, which should be used in preference - * to these. + * Math routines similar to those found in {@link java.lang.Math}. + * + *

Historically these methods were faster than the equivalent double-based + * {@link java.lang.Math} methods. On versions of Android with a JIT they + * became slower and have since been re-implemented to wrap calls to + * {@link java.lang.Math}. {@link java.lang.Math} should be used in + * preference. */ public class FloatMath { -- cgit v1.1