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go/test/loopbce.go
David Chase 0b6fbaae6e cmd/compile: make loop guard+rotate conditional on GOEXPERIMENT 
Loops of the form "for i,e := range" needed to have their
condition rotated to the "bottom" for the preemptible loops
GOEXPERIMENT, but this caused a performance regression
because it degraded bounds check removal.  For now, make
the loop rotation/guarding conditional on the experiment.

Fixes #20711.
Updates #10958.

Change-Id: Icfba14cb3b13a910c349df8f84838cf4d9d20cf6
Reviewed-on: https://go-review.googlesource.com/46410
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2017-06-21 22:07:33 +00:00

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// +build amd64
// errorcheck -0 -d=ssa/loopbce/debug=3
package main
func f0a(a []int) int {
x := 0
for i := range a { // ERROR "Induction variable with minimum 0 and increment 1$"
x += a[i] // ERROR "Found redundant IsInBounds$"
}
return x
}
func f0b(a []int) int {
x := 0
for i := range a { // ERROR "Induction variable with minimum 0 and increment 1$"
b := a[i:] // ERROR "Found redundant IsSliceInBounds$"
x += b[0]
}
return x
}
func f0c(a []int) int {
x := 0
for i := range a { // ERROR "Induction variable with minimum 0 and increment 1$"
b := a[:i+1] // ERROR "Found redundant IsSliceInBounds \(len promoted to cap\)$"
x += b[0]
}
return x
}
func f1(a []int) int {
x := 0
for _, i := range a { // ERROR "Induction variable with minimum 0 and increment 1"
x += i
}
return x
}
func f2(a []int) int {
x := 0
for i := 1; i < len(a); i++ { // ERROR "Induction variable with minimum 1 and increment 1$"
x += a[i] // ERROR "Found redundant IsInBounds$"
}
return x
}
func f4(a [10]int) int {
x := 0
for i := 0; i < len(a); i += 2 { // ERROR "Induction variable with minimum 0 and increment 2$"
x += a[i] // ERROR "Found redundant IsInBounds$"
}
return x
}
func f5(a [10]int) int {
x := 0
for i := -10; i < len(a); i += 2 { // ERROR "Induction variable with minimum -10 and increment 2$"
x += a[i]
}
return x
}
func f6(a []int) {
for i := range a { // ERROR "Induction variable with minimum 0 and increment 1$"
b := a[0:i] // ERROR "Found redundant IsSliceInBounds \(len promoted to cap\)$"
f6(b)
}
}
func g0a(a string) int {
x := 0
for i := 0; i < len(a); i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
x += int(a[i]) // ERROR "Found redundant IsInBounds$"
}
return x
}
func g0b(a string) int {
x := 0
for i := 0; len(a) > i; i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
x += int(a[i]) // ERROR "Found redundant IsInBounds$"
}
return x
}
func g1() int {
a := "evenlength"
x := 0
for i := 0; i < len(a); i += 2 { // ERROR "Induction variable with minimum 0 and increment 2$"
x += int(a[i]) // ERROR "Found redundant IsInBounds$"
}
return x
}
func g2() int {
a := "evenlength"
x := 0
for i := 0; i < len(a); i += 2 { // ERROR "Induction variable with minimum 0 and increment 2$"
j := i
if a[i] == 'e' { // ERROR "Found redundant IsInBounds$"
j = j + 1
}
x += int(a[j])
}
return x
}
func g3a() {
a := "this string has length 25"
for i := 0; i < len(a); i += 5 { // ERROR "Induction variable with minimum 0 and increment 5$"
useString(a[i:]) // ERROR "Found redundant IsSliceInBounds$"
useString(a[:i+3])
}
}
func g3b(a string) {
for i := 0; i < len(a); i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
useString(a[i+1:]) // ERROR "Found redundant IsSliceInBounds$"
}
}
func g3c(a string) {
for i := 0; i < len(a); i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
useString(a[:i+1]) // ERROR "Found redundant IsSliceInBounds$"
}
}
func h1(a []byte) {
c := a[:128]
for i := range c { // ERROR "Induction variable with minimum 0 and increment 1$"
c[i] = byte(i) // ERROR "Found redundant IsInBounds$"
}
}
func h2(a []byte) {
for i := range a[:128] { // ERROR "Induction variable with minimum 0 and increment 1$"
a[i] = byte(i)
}
}
func k0(a [100]int) [100]int {
for i := 10; i < 90; i++ { // ERROR "Induction variable with minimum 10 and increment 1$"
a[i-11] = i
a[i-10] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 80$"
a[i-5] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 85$"
a[i] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 90$"
a[i+5] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 95$"
a[i+10] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 100$"
a[i+11] = i
}
return a
}
func k1(a [100]int) [100]int {
for i := 10; i < 90; i++ { // ERROR "Induction variable with minimum 10 and increment 1$"
useSlice(a[:i-11])
useSlice(a[:i-10]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 80$"
useSlice(a[:i-5]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 85$"
useSlice(a[:i]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 90$"
useSlice(a[:i+5]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 95$"
useSlice(a[:i+10]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 100$"
useSlice(a[:i+11]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 101$"
}
return a
}
func k2(a [100]int) [100]int {
for i := 10; i < 90; i++ { // ERROR "Induction variable with minimum 10 and increment 1$"
useSlice(a[i-11:])
useSlice(a[i-10:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 80$"
useSlice(a[i-5:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 85$"
useSlice(a[i:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 90$"
useSlice(a[i+5:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 95$"
useSlice(a[i+10:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 100$"
useSlice(a[i+11:]) // ERROR "Found redundant \(IsSliceInBounds ind 100\), ind < 101$"
}
return a
}
func k3(a [100]int) [100]int {
for i := -10; i < 90; i++ { // ERROR "Induction variable with minimum -10 and increment 1$"
a[i+10] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 100$"
}
return a
}
func k4(a [100]int) [100]int {
min := (-1) << 63
for i := min; i < min+50; i++ { // ERROR "Induction variable with minimum -9223372036854775808 and increment 1$"
a[i-min] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 50$"
}
return a
}
func k5(a [100]int) [100]int {
max := (1 << 63) - 1
for i := max - 50; i < max; i++ { // ERROR "Induction variable with minimum 9223372036854775757 and increment 1$"
a[i-max+50] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 50$"
a[i-(max-70)] = i // ERROR "Found redundant \(IsInBounds ind 100\), ind < 70$"
}
return a
}
func nobce1() {
// tests overflow of max-min
a := int64(9223372036854774057)
b := int64(-1547)
z := int64(1337)
if a%z == b%z {
panic("invalid test: modulos should differ")
}
for i := b; i < a; i += z {
// No induction variable is possible because i will overflow a first iteration.
useString("foobar")
}
}
func nobce2(a string) {
for i := int64(0); i < int64(len(a)); i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
useString(a[i:]) // ERROR "Found redundant IsSliceInBounds$"
}
for i := int64(0); i < int64(len(a))-31337; i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
useString(a[i:]) // ERROR "Found redundant IsSliceInBounds$"
}
for i := int64(0); i < int64(len(a))+int64(-1<<63); i++ { // ERROR "Induction variable with minimum 0 and increment 1$"
// tests an overflow of StringLen-MinInt64
useString(a[i:])
}
}
func nobce3(a [100]int64) [100]int64 {
min := int64((-1) << 63)
max := int64((1 << 63) - 1)
for i := min; i < max; i++ { // ERROR "Induction variable with minimum -9223372036854775808 and increment 1$"
a[i] = i
}
return a
}
//go:noinline
func useString(a string) {
}
//go:noinline
func useSlice(a []int) {
}
func main() {
}
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