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Revert "reflect: when Converting between float32s, don't lose signal NaNs"

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This reverts commit 7485050c0f.

Reason for revert: Breaking some builders (387, mips, mips64)

Change-Id: I33e5125b7a9a96b55bc5e71880fca4ee30d226a7
Reviewed-on: https://go-review.googlesource.com/c/go/+/220695
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Keith Randall 2020-02-25 05:57:22 +00:00
parent 0d4fa27fd7
commit 0d6b317ee6
2 changed files with 0 additions and 25 deletions
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11
src/reflect/all_test.go
View File

@ -4163,17 +4163,6 @@ func TestConvert(t *testing.T) {
} }
} }
func TestConvertNaNs(t *testing.T) {
const snan uint32 = 0x7f800001
type myFloat32 float32
x := V(myFloat32(math.Float32frombits(snan)))
y := x.Convert(TypeOf(float32(0)))
z := y.Interface().(float32)
if got := math.Float32bits(z); got != snan {
t.Errorf("signaling nan conversion got %x, want %x", got, snan)
}
}
type ComparableStruct struct { type ComparableStruct struct {
X int X int
} }

14
src/reflect/value.go
View File

@ -2541,14 +2541,6 @@ func makeFloat(f flag, v float64, t Type) Value {
return Value{typ, ptr, f | flagIndir | flag(typ.Kind())} return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
} }
// makeFloat returns a Value of type t equal to v, where t is a float32 type.
func makeFloat32(f flag, v float32, t Type) Value {
typ := t.common()
ptr := unsafe_New(typ)
*(*float32)(ptr) = v
return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
}
// makeComplex returns a Value of type t equal to v (possibly truncated to complex64), // makeComplex returns a Value of type t equal to v (possibly truncated to complex64),
// where t is a complex64 or complex128 type. // where t is a complex64 or complex128 type.
func makeComplex(f flag, v complex128, t Type) Value { func makeComplex(f flag, v complex128, t Type) Value {
@ -2621,12 +2613,6 @@ func cvtUintFloat(v Value, t Type) Value {
// convertOp: floatXX -> floatXX // convertOp: floatXX -> floatXX
func cvtFloat(v Value, t Type) Value { func cvtFloat(v Value, t Type) Value {
if v.Type().Kind() == Float32 && t.Kind() == Float32 {
// Don't do any conversion if both types have underlying type float32.
// This avoids converting to float64 and back, which will
// convert a signaling NaN to a quiet NaN. See issue 36400.
return makeFloat32(v.flag.ro(), *(*float32)(v.ptr), t)
}
return makeFloat(v.flag.ro(), v.Float(), t) return makeFloat(v.flag.ro(), v.Float(), t)
} }