tiny speedup to DenseVector#foreach

dlwh · Jul 31, 2015 · 5fccba1 · 5fccba1
1 parent e25db29
commit 5fccba1
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Showing 2 changed files with 25 additions and 6 deletions.
diff --git a/benchmark/src/main/scala/breeze/linalg/DenseVectorBenchmark.scala b/benchmark/src/main/scala/breeze/linalg/DenseVectorBenchmark.scala
@@ -54,6 +54,21 @@ class DenseVectorBenchmark extends BreezeBenchmark with BuildsRandomVectors {
     DenseVector.fill[Double](1024, 23)
   }
 
+  def timeForeach(reps: Int) = runWith(reps, randomArray(4000)) { arr =>
+    var sum = 0.0
+    arr.foreach(sum += _)
+    sum
+  }
+
+  def timeLoop(reps: Int) = runWith(reps, randomArray(4000)) { arr =>
+    var sum = 0.0
+    val d = arr.data
+    cforRange(0 until arr.length) { i =>
+      sum += d(i)
+    }
+    sum
+  }
+
   def valueAtBench(reps: Int, size: Int, stride: Int) = runWith(reps, {randomArray(size, stride=stride)})(arr => {
     var i=0
     var t: Double = 0

diff --git a/math/src/main/scala/breeze/linalg/DenseVector.scala b/math/src/main/scala/breeze/linalg/DenseVector.scala
@@ -161,12 +161,16 @@ class DenseVector[@spec(Double, Int, Float, Long) V](val data: Array[V],
    * @tparam U
    */
   override def foreach[@spec(Unit) U](fn: (V) => U): Unit = {
-    var i = offset
-    var j = 0
-    while(j < length) {
-      fn(data(i))
-      i += stride
-      j += 1
+    if (stride == 1) { // ABCE stuff
+      cforRange(offset until (offset + length)) { j =>
+        fn(data(j))
+      }
+    } else {
+      var i = offset
+      cforRange(0 until length) { j =>
+        fn(data(i))
+        i += stride
+      }
     }
   }