1 files changed, 37 insertions, 28 deletions

diff --git a/libgo/go/math/big/calibrate_test.go b/libgo/go/math/big/calibrate_test.go
index 2b96e74a658..4fa663ff083 100644
--- a/libgo/go/math/big/calibrate_test.go
+++ b/libgo/go/math/big/calibrate_test.go
@@ -28,24 +28,32 @@ import (
 
 var calibrate = flag.Bool("calibrate", false, "run calibration test")
 
+const (
+	sqrModeMul       = "mul(x, x)"
+	sqrModeBasic     = "basicSqr(x)"
+	sqrModeKaratsuba = "karatsubaSqr(x)"
+)
+
 func TestCalibrate(t *testing.T) {
-	if *calibrate {
-		computeKaratsubaThresholds()
-
-		// compute basicSqrThreshold where overhead becomes negligible
-		minSqr := computeSqrThreshold(10, 30, 1, 3)
-		// compute karatsubaSqrThreshold where karatsuba is faster
-		maxSqr := computeSqrThreshold(300, 500, 10, 3)
-		if minSqr != 0 {
-			fmt.Printf("found basicSqrThreshold = %d\n", minSqr)
-		} else {
-			fmt.Println("no basicSqrThreshold found")
-		}
-		if maxSqr != 0 {
-			fmt.Printf("found karatsubaSqrThreshold = %d\n", maxSqr)
-		} else {
-			fmt.Println("no karatsubaSqrThreshold found")
-		}
+	if !*calibrate {
+		return
+	}
+
+	computeKaratsubaThresholds()
+
+	// compute basicSqrThreshold where overhead becomes negligible
+	minSqr := computeSqrThreshold(10, 30, 1, 3, sqrModeMul, sqrModeBasic)
+	// compute karatsubaSqrThreshold where karatsuba is faster
+	maxSqr := computeSqrThreshold(200, 500, 10, 3, sqrModeBasic, sqrModeKaratsuba)
+	if minSqr != 0 {
+		fmt.Printf("found basicSqrThreshold = %d\n", minSqr)
+	} else {
+		fmt.Println("no basicSqrThreshold found")
+	}
+	if maxSqr != 0 {
+		fmt.Printf("found karatsubaSqrThreshold = %d\n", maxSqr)
+	} else {
+		fmt.Println("no karatsubaSqrThreshold found")
 	}
 }
 
@@ -109,16 +117,17 @@ func computeKaratsubaThresholds() {
 	}
 }
 
-func measureBasicSqr(words, nruns int, enable bool) time.Duration {
+func measureSqr(words, nruns int, mode string) time.Duration {
 	// more runs for better statistics
 	initBasicSqr, initKaratsubaSqr := basicSqrThreshold, karatsubaSqrThreshold
 
-	if enable {
-		// set thresholds to use basicSqr at this number of words
+	switch mode {
+	case sqrModeMul:
+		basicSqrThreshold = words + 1
+	case sqrModeBasic:
 		basicSqrThreshold, karatsubaSqrThreshold = words-1, words+1
-	} else {
-		// set thresholds to disable basicSqr for any number of words
-		basicSqrThreshold, karatsubaSqrThreshold = -1, -1
+	case sqrModeKaratsuba:
+		karatsubaSqrThreshold = words - 1
 	}
 
 	var testval int64
@@ -133,18 +142,18 @@ func measureBasicSqr(words, nruns int, enable bool) time.Duration {
 	return time.Duration(testval)
 }
 
-func computeSqrThreshold(from, to, step, nruns int) int {
-	fmt.Println("Calibrating thresholds for basicSqr via benchmarks of z.mul(x,x)")
+func computeSqrThreshold(from, to, step, nruns int, lower, upper string) int {
+	fmt.Printf("Calibrating threshold between %s and %s\n", lower, upper)
 	fmt.Printf("Looking for a timing difference for x between %d - %d words by %d step\n", from, to, step)
 	var initPos bool
 	var threshold int
 	for i := from; i <= to; i += step {
-		baseline := measureBasicSqr(i, nruns, false)
-		testval := measureBasicSqr(i, nruns, true)
+		baseline := measureSqr(i, nruns, lower)
+		testval := measureSqr(i, nruns, upper)
 		pos := baseline > testval
 		delta := baseline - testval
 		percent := delta * 100 / baseline
-		fmt.Printf("words = %3d deltaT = %10s (%4d%%) is basicSqr better: %v", i, delta, percent, pos)
+		fmt.Printf("words = %3d deltaT = %10s (%4d%%) is %s better: %v", i, delta, percent, upper, pos)
 		if i == from {
 			initPos = pos
 		}