just made some tests to check the new SSA BCE feature.
It is cool by removing many unnecessary bounds checks.
But I still found some cases where I think BCE should also be applied but
not.
I don't know if they are intended or not.
// example4.go
package main
import "math/rand"
func fa2() {
s := []int{0, 1, 2, 3, 4, 5, 6}
index := rand.Intn(7)
_ = s[index:] // line 9: bounds check
_ = s[:index] // line 10: bounds check eliminatd!
}
func fb2(s []int, index int) {
_ = s[index:] // line 14: bounds check
_ = s[:index] // line 15: bounds check // not clever enough?
}
func fc2() {
s := []int{0, 1, 2, 3, 4, 5, 6}
s = s[:4]
index := rand.Intn(7)
_ = s[index:] // line 22: bounds check
_ = s[:index] // line 23: bounds check eliminatd!
}
func fd2(s []int) {
for i := len(s) - 1; i >= 0; i -- {
_ = s[i] // line 28: bounds check
_ = s[i:len(s)]
}
}
func main() {}
//////////////////////////////
////
go build -gcflags="-d=ssa/check_bce/
debug=1" 11.go
# command-line-arguments
./11.go:9: Found IsSliceInBounds
./11.go:14: Found IsSliceInBounds
./11.go:15: Found IsSliceInBounds
./11.go:22: Found IsSliceInBounds
./11.go:28: Found IsInBounds
where line 15 in fb2 and line 28 in fd2 should be BCEed, I think, but not.
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