cmd/compile: bad compilation with inlined math functions #23522
Description
This test case is miscompiled with devel +9745eed4fd Fri Jan 12 05:25:55 2018. The programs panics when it should not. This passes with Go 1.9 and gccgo.
CC @randall77
package main
import (
"math"
)
type S struct {
u int64
n int32
}
func F1(f float64) *S {
s := f
pf := math.Copysign(f, 1)
u := math.Floor(pf)
return &S{
u: int64(math.Copysign(u, s)),
n: int32(math.Copysign((pf-u)*1e9, s)),
}
}
func F2(f float64) *S {
s := f
f = math.Copysign(f, 1)
u := math.Floor(f)
return &S{
u: int64(math.Copysign(u, s)),
n: int32(math.Copysign((f-u)*1e9, s)),
}
}
func main() {
s1 := F1(-1)
s2 := F2(-1)
if *s1 != *s2 {
println("F1:", s1.u, s1.n)
println("F2:", s2.u, s2.n)
panic("different")
}
}