math: fix Pow10 loop
Pow10 failed for MinInt32 (endless loop until out of
memory). Fix by returning 0 and +Inf for all arguments
where the result is not representable in a float64.
Fixes #2159.
R=rsc
CC=golang-dev
https://golang.org/cl/4930041
diff --git a/src/pkg/math/all_test.go b/src/pkg/math/all_test.go
index d2a7d41..1fe4513 100644
--- a/src/pkg/math/all_test.go
+++ b/src/pkg/math/all_test.go
@@ -1359,6 +1359,20 @@
NaN(), // pow(NaN, NaN)
}
+var vfpow10SC = []int{
+ MinInt32,
+ MaxInt32,
+ -325,
+ 309,
+}
+
+var pow10SC = []float64{
+ 0, // pow10(MinInt32)
+ Inf(1), // pow10(MaxInt32)
+ 0, // pow10(-325)
+ Inf(1), // pow10(309)
+}
+
var vfsignbitSC = []float64{
Inf(-1),
Copysign(0, -1),
@@ -2143,6 +2157,14 @@
}
}
+func TestPow10(t *testing.T) {
+ for i := 0; i < len(vfpow10SC); i++ {
+ if f := Pow10(vfpow10SC[i]); !alike(pow10SC[i], f) {
+ t.Errorf("Pow10(%d) = %g, want %g", vfpow10SC[i], f, pow10SC[i])
+ }
+ }
+}
+
func TestRemainder(t *testing.T) {
for i := 0; i < len(vf); i++ {
if f := Remainder(10, vf[i]); remainder[i] != f {
@@ -2659,6 +2681,18 @@
}
}
+func BenchmarkPow10Pos(b *testing.B) {
+ for i := 0; i < b.N; i++ {
+ Pow10(300)
+ }
+}
+
+func BenchmarkPow10Neg(b *testing.B) {
+ for i := 0; i < b.N; i++ {
+ Pow10(-300)
+ }
+}
+
func BenchmarkRemainder(b *testing.B) {
for i := 0; i < b.N; i++ {
Remainder(10, 3)
