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-rw-r--r--test/fixedbugs/issue14651.go71
1 files changed, 71 insertions, 0 deletions
diff --git a/test/fixedbugs/issue14651.go b/test/fixedbugs/issue14651.go
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+// run
+
+// Copyright 2016 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 test checks if the compiler's internal constant
+// arithmetic correctly rounds up floating-point values
+// that become the smallest denormal value.
+//
+// See also related issue 14553 and test issue14553.go.
+
+package main
+
+import (
+ "fmt"
+ "math"
+)
+
+const (
+ p149 = 1.0 / (1 << 149) // 1p-149
+ p500 = 1.0 / (1 << 500) // 1p-500
+ p1074 = p500 * p500 / (1<<74) // 1p-1074
+)
+
+const (
+ m0000p149 = 0x0 / 16.0 * p149 // = 0.0000p-149
+ m1000p149 = 0x8 / 16.0 * p149 // = 0.1000p-149
+ m1001p149 = 0x9 / 16.0 * p149 // = 0.1001p-149
+ m1011p149 = 0xb / 16.0 * p149 // = 0.1011p-149
+ m1100p149 = 0xc / 16.0 * p149 // = 0.1100p-149
+
+ m0000p1074 = 0x0 / 16.0 * p1074 // = 0.0000p-1074
+ m1000p1074 = 0x8 / 16.0 * p1074 // = 0.1000p-1074
+ m1001p1074 = 0x9 / 16.0 * p1074 // = 0.1001p-1074
+ m1011p1074 = 0xb / 16.0 * p1074 // = 0.1011p-1074
+ m1100p1074 = 0xc / 16.0 * p1074 // = 0.1100p-1074
+)
+
+func main() {
+ test32(float32(m0000p149), f32(m0000p149))
+ test32(float32(m1000p149), f32(m1000p149))
+ test32(float32(m1001p149), f32(m1001p149))
+ test32(float32(m1011p149), f32(m1011p149))
+ test32(float32(m1100p149), f32(m1100p149))
+
+ test64(float64(m0000p1074), f64(m0000p1074))
+ test64(float64(m1000p1074), f64(m1000p1074))
+ test64(float64(m1001p1074), f64(m1001p1074))
+ test64(float64(m1011p1074), f64(m1011p1074))
+ test64(float64(m1100p1074), f64(m1100p1074))
+}
+
+func f32(x float64) float32 { return float32(x) }
+func f64(x float64) float64 { return float64(x) }
+
+func test32(a, b float32) {
+ abits := math.Float32bits(a)
+ bbits := math.Float32bits(b)
+ if abits != bbits {
+ panic(fmt.Sprintf("%08x != %08x\n", abits, bbits))
+ }
+}
+
+func test64(a, b float64) {
+ abits := math.Float64bits(a)
+ bbits := math.Float64bits(b)
+ if abits != bbits {
+ panic(fmt.Sprintf("%016x != %016x\n", abits, bbits))
+ }
+}