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Revert "math: add Compare and Compare32"

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This reverts CL 459435.

Reason for revert: Tests failing on MIPS.

Change-Id: I9017bf718ba938df6d6766041555034d55d90b8a
Reviewed-on: https://go-review.googlesource.com/c/go/+/467255
Run-TryBot: Than McIntosh <thanm@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Akhil Indurti <aindurti@gmail.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
This commit is contained in:
Than McIntosh 2023-02-10 14:39:20 +00:00
parent aa5b22552a
commit ac8a97ac9e
3 changed files with 0 additions and 114 deletions
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2
api/next/56491.txt
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@ -1,2 +0,0 @@
pkg math, func Compare(float64, float64) int #56491
pkg math, func Compare32(float32, float32) int #56491

59
src/math/all_test.go
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@ -2094,33 +2094,6 @@ var sqrt32 = []float32{
-5.0106036182710749e+00,
}
type compareTest[F float32 | float64] struct {
x, y F
want int
}
func compareCases[F float32 | float64]() []compareTest[F] {
zero, nan, inf := F(0.0), F(NaN()), F(Inf(0))
return []compareTest[F]{
{-nan, -inf, -1},
{-inf, -nan, 1},
{-inf, -Pi, -1},
{-Pi, -inf, 1},
{-Pi, -zero, -1},
{-zero, -Pi, 1},
{-zero, 0, -1},
{0, -zero, 1},
{0, Pi, -1},
{Pi, 0, 1},
{Pi, inf, -1},
{inf, Pi, 1},
{inf, nan, -1},
{nan, inf, 1},
{Pi, Pi, 0},
{-nan, -nan, 0},
}
}
func tolerance(a, b, e float64) bool {
// Multiplying by e here can underflow denormal values to zero.
// Check a==b so that at least if a and b are small and identical
@ -2288,22 +2261,6 @@ func TestCeil(t *testing.T) {
}
}
func TestCompare(t *testing.T) {
// -NaN < -∞ < -3.14 < -0 < 0 < 3.14 < ∞ < NaN
for _, c := range compareCases[float64]() {
cmp := Compare(c.x, c.y)
if cmp != c.want {
t.Errorf("Compare(%v, %v) = %d, want %v", c.x, c.y, cmp, c.want)
}
}
for _, c := range compareCases[float32]() {
cmp := Compare32(c.x, c.y)
if cmp != c.want {
t.Errorf("Compare32(%v, %v) = %d, want %v", c.x, c.y, cmp, c.want)
}
}
}
func TestCopysign(t *testing.T) {
for i := 0; i < len(vf); i++ {
if f := Copysign(vf[i], -1); copysign[i] != f {
@ -3363,22 +3320,6 @@ func BenchmarkCeil(b *testing.B) {
GlobalF = x
}
func BenchmarkCompare(b *testing.B) {
x := 0
for i := 0; i < b.N; i++ {
x = Compare(1.5, 2.5)
}
GlobalI = x
}
func BenchmarkCompare32(b *testing.B) {
x := 0
for i := 0; i < b.N; i++ {
x = Compare32(1.5, 2.5)
}
GlobalI = x
}
var copysignNeg = -1.0
func BenchmarkCopysign(b *testing.B) {

53
src/math/compare.go
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@ -1,53 +0,0 @@
// Copyright 2023 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.
package math
func sign[I int32 | int64](a, b I) int {
if a < b {
return -1
}
if a > b {
return 1
}
return 0
}
// Compare compares a and b such that
// -NaN is ordered before any other value,
// +NaN is ordered after any other value,
// and -0 is ordered before +0.
// In other words, it defines a total order over floats
// (according to the total-ordering predicate in IEEE-754, section 5.10).
// It returns 0 if a == b, -1 if a < b, and +1 if a > b.
func Compare(a, b float64) int {
// Perform a bitwise comparison (a < b) by casting the float64s into an int64s.
x := int64(Float64bits(a))
y := int64(Float64bits(b))
// If a and b are both negative, flip the comparison so that we check a > b.
if x < 0 && y < 0 {
return sign(y, x)
}
return sign(x, y)
}
// Compare32 compares a and b such that
// -NaN is ordered before any other value,
// +NaN is ordered after any other value,
// and -0 is ordered before +0.
// In other words, it defines a total order over floats
// (according to the total-ordering predicate in IEEE-754, section 5.10).
// It returns 0 if a == b, -1 if a < b, and +1 if a > b.
func Compare32(a, b float32) int {
// Perform a bitwise comparison (a < b) by casting the float32s into an int32s.
x := int32(Float32bits(a))
y := int32(Float32bits(b))
// If a and b are both negative, flip the comparison so that we check a > b.
if x < 0 && y < 0 {
return sign(y, x)
}
return sign(x, y)
}