libgo: Merge from revision 18783:00cce3a34d7e of master library.

This revision was committed January 7, 2014.  The next
revision deleted runtime/mfinal.c.  That will be done in a
subsequent merge.

This merge changes type descriptors to add a zero field,
pointing to a zero value for that type.  This is implemented
as a common variable.

	* go-gcc.cc (Gcc_backend::implicit_variable): Add is_common and
	alignment parameters.  Permit init parameter to be NULL.

From-SVN: r211249

2 files changed, 36 insertions, 6 deletions

diff --git a/libgo/go/math/rand/rand.go b/libgo/go/math/rand/rand.go
index 2157cdb..d3ea840 100644
--- a/libgo/go/math/rand/rand.go
+++ b/libgo/go/math/rand/rand.go
@@ -95,20 +95,18 @@ func (r *Rand) Intn(n int) int {
 }
 
 // Float64 returns, as a float64, a pseudo-random number in [0.0,1.0).
-func (r *Rand) Float64() float64 { return float64(r.Int63()) / (1 << 63) }
+func (r *Rand) Float64() float64 { return float64(r.Int63n(1<<53)) / (1 << 53) }
 
 // Float32 returns, as a float32, a pseudo-random number in [0.0,1.0).
-func (r *Rand) Float32() float32 { return float32(r.Float64()) }
+func (r *Rand) Float32() float32 { return float32(r.Int31n(1<<24)) / (1 << 24) }
 
 // Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n).
 func (r *Rand) Perm(n int) []int {
 	m := make([]int, n)
 	for i := 0; i < n; i++ {
-		m[i] = i
-	}
-	for i := 0; i < n; i++ {
 		j := r.Intn(i + 1)
-		m[i], m[j] = m[j], m[i]
+		m[i] = m[j]
+		m[j] = i
 	}
 	return m
 }
diff --git a/libgo/go/math/rand/rand_test.go b/libgo/go/math/rand/rand_test.go
index 4d3abdb..c174c61 100644
--- a/libgo/go/math/rand/rand_test.go
+++ b/libgo/go/math/rand/rand_test.go
@@ -322,6 +322,17 @@ func TestExpTables(t *testing.T) {
 	}
 }
 
+// For issue 6721, the problem came after 7533753 calls, so check 10e6.
+func TestFloat32(t *testing.T) {
+	r := New(NewSource(1))
+	for ct := 0; ct < 10e6; ct++ {
+		f := r.Float32()
+		if f >= 1 {
+			t.Fatal("Float32() should be in range [0,1). ct:", ct, "f:", f)
+		}
+	}
+}
+
 // Benchmarks
 
 func BenchmarkInt63Threadsafe(b *testing.B) {
@@ -357,3 +368,24 @@ func BenchmarkInt31n1000(b *testing.B) {
 		r.Int31n(1000)
 	}
 }
+
+func BenchmarkFloat32(b *testing.B) {
+	r := New(NewSource(1))
+	for n := b.N; n > 0; n-- {
+		r.Float32()
+	}
+}
+
+func BenchmarkPerm3(b *testing.B) {
+	r := New(NewSource(1))
+	for n := b.N; n > 0; n-- {
+		r.Perm(3)
+	}
+}
+
+func BenchmarkPerm30(b *testing.B) {
+	r := New(NewSource(1))
+	for n := b.N; n > 0; n-- {
+		r.Perm(30)
+	}
+}