1 files changed, 84 insertions, 0 deletions
diff --git a/test/bench/go1/fannkuch_test.go b/test/bench/go1/fannkuch_test.go
new file mode 100644
index 0000000..0cf6115
--- /dev/null
+++ b/test/bench/go1/fannkuch_test.go
@@ -0,0 +1,84 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This benchmark, taken from the shootout, tests array indexing
+// and array bounds elimination performance.
+
+package go1
+
+import "testing"
+
+func fannkuch(n int) int {
+	if n < 1 {
+		return 0
+	}
+
+	n1 := n - 1
+	perm := make([]int, n)
+	perm1 := make([]int, n)
+	count := make([]int, n)
+
+	for i := 0; i < n; i++ {
+		perm1[i] = i // initial (trivial) permutation
+	}
+
+	r := n
+	didpr := 0
+	flipsMax := 0
+	for {
+		if didpr < 30 {
+			didpr++
+		}
+		for ; r != 1; r-- {
+			count[r-1] = r
+		}
+
+		if perm1[0] != 0 && perm1[n1] != n1 {
+			flips := 0
+			for i := 1; i < n; i++ { // perm = perm1
+				perm[i] = perm1[i]
+			}
+			k := perm1[0] // cache perm[0] in k
+			for {         // k!=0 ==> k>0
+				for i, j := 1, k-1; i < j; i, j = i+1, j-1 {
+					perm[i], perm[j] = perm[j], perm[i]
+				}
+				flips++
+				// Now exchange k (caching perm[0]) and perm[k]... with care!
+				j := perm[k]
+				perm[k] = k
+				k = j
+				if k == 0 {
+					break
+				}
+			}
+			if flipsMax < flips {
+				flipsMax = flips
+			}
+		}
+
+		for ; r < n; r++ {
+			// rotate down perm[0..r] by one
+			perm0 := perm1[0]
+			for i := 0; i < r; i++ {
+				perm1[i] = perm1[i+1]
+			}
+			perm1[r] = perm0
+			count[r]--
+			if count[r] > 0 {
+				break
+			}
+		}
+		if r == n {
+			return flipsMax
+		}
+	}
+	return 0
+}
+
+func BenchmarkFannkuch11(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		fannkuch(11)
+	}
+}