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go/test/prove.go
Keith Randall 73f92f9b04 cmd/compile: use len(s)<=cap(s) to remove more bounds checks 
When we discover a relation x <= len(s), also discover the relation
x <= cap(s).  That way, in situations like:

a := s[x:]  // tests 0 <= x <= len(s)
b := s[:x]  // tests 0 <= x <= cap(s)

the second check can be eliminated.

Fixes #16813

Change-Id: Ifc037920b6955e43bac1a1eaf6bac63a89cfbd44
Reviewed-on: https://go-review.googlesource.com/33633
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alexandru Moșoi <alexandru@mosoi.ro>
Reviewed-by: David Chase <drchase@google.com>
2017-02-02 17:45:58 +00:00

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// +build amd64
// errorcheck -0 -d=ssa/prove/debug=1
// Copyright 2016 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 main
import "math"
func f0(a []int) int {
a[0] = 1
a[0] = 1 // ERROR "Proved boolean IsInBounds$"
a[6] = 1
a[6] = 1 // ERROR "Proved boolean IsInBounds$"
a[5] = 1 // ERROR "Proved IsInBounds$"
a[5] = 1 // ERROR "Proved boolean IsInBounds$"
return 13
}
func f1(a []int) int {
if len(a) <= 5 {
return 18
}
a[0] = 1 // ERROR "Proved non-negative bounds IsInBounds$"
a[0] = 1 // ERROR "Proved boolean IsInBounds$"
a[6] = 1
a[6] = 1 // ERROR "Proved boolean IsInBounds$"
a[5] = 1 // ERROR "Proved IsInBounds$"
a[5] = 1 // ERROR "Proved boolean IsInBounds$"
return 26
}
func f1b(a []int, i int, j uint) int {
if i >= 0 && i < len(a) {
return a[i] // ERROR "Proved non-negative bounds IsInBounds$"
}
if i >= 10 && i < len(a) {
return a[i] // ERROR "Proved non-negative bounds IsInBounds$"
}
if i >= 10 && i < len(a) {
return a[i] // ERROR "Proved non-negative bounds IsInBounds$"
}
if i >= 10 && i < len(a) { // todo: handle this case
return a[i-10]
}
if j < uint(len(a)) {
return a[j] // ERROR "Proved IsInBounds$"
}
return 0
}
func f1c(a []int, i int64) int {
c := uint64(math.MaxInt64 + 10) // overflows int
d := int64(c)
if i >= d && i < int64(len(a)) {
// d overflows, should not be handled.
return a[i]
}
return 0
}
func f2(a []int) int {
for i := range a {
a[i+1] = i
a[i+1] = i // ERROR "Proved boolean IsInBounds$"
}
return 34
}
func f3(a []uint) int {
for i := uint(0); i < uint(len(a)); i++ {
a[i] = i // ERROR "Proved IsInBounds$"
}
return 41
}
func f4a(a, b, c int) int {
if a < b {
if a == b { // ERROR "Disproved Eq64$"
return 47
}
if a > b { // ERROR "Disproved Greater64$"
return 50
}
if a < b { // ERROR "Proved boolean Less64$"
return 53
}
if a == b { // ERROR "Disproved boolean Eq64$"
return 56
}
if a > b { // ERROR "Disproved boolean Greater64$"
return 59
}
return 61
}
return 63
}
func f4b(a, b, c int) int {
if a <= b {
if a >= b {
if a == b { // ERROR "Proved Eq64$"
return 70
}
return 75
}
return 77
}
return 79
}
func f4c(a, b, c int) int {
if a <= b {
if a >= b {
if a != b { // ERROR "Disproved Neq64$"
return 73
}
return 75
}
return 77
}
return 79
}
func f4d(a, b, c int) int {
if a < b {
if a < c {
if a < b { // ERROR "Proved boolean Less64$"
if a < c { // ERROR "Proved boolean Less64$"
return 87
}
return 89
}
return 91
}
return 93
}
return 95
}
func f4e(a, b, c int) int {
if a < b {
if b > a { // ERROR "Proved Greater64$"
return 101
}
return 103
}
return 105
}
func f4f(a, b, c int) int {
if a <= b {
if b > a {
if b == a { // ERROR "Disproved Eq64$"
return 112
}
return 114
}
if b >= a { // ERROR "Proved Geq64$"
if b == a { // ERROR "Proved Eq64$"
return 118
}
return 120
}
return 122
}
return 124
}
func f5(a, b uint) int {
if a == b {
if a <= b { // ERROR "Proved Leq64U$"
return 130
}
return 132
}
return 134
}
// These comparisons are compile time constants.
func f6a(a uint8) int {
if a < a { // ERROR "Disproved Less8U$"
return 140
}
return 151
}
func f6b(a uint8) int {
if a < a { // ERROR "Disproved Less8U$"
return 140
}
return 151
}
func f6x(a uint8) int {
if a > a { // ERROR "Disproved Greater8U$"
return 143
}
return 151
}
func f6d(a uint8) int {
if a <= a { // ERROR "Proved Leq8U$"
return 146
}
return 151
}
func f6e(a uint8) int {
if a >= a { // ERROR "Proved Geq8U$"
return 149
}
return 151
}
func f7(a []int, b int) int {
if b < len(a) {
a[b] = 3
if b < len(a) { // ERROR "Proved boolean Less64$"
a[b] = 5 // ERROR "Proved boolean IsInBounds$"
}
}
return 161
}
func f8(a, b uint) int {
if a == b {
return 166
}
if a > b {
return 169
}
if a < b { // ERROR "Proved Less64U$"
return 172
}
return 174
}
func f9(a, b bool) int {
if a {
return 1
}
if a || b { // ERROR "Disproved boolean Arg$"
return 2
}
return 3
}
func f10(a string) int {
n := len(a)
if a[:n>>1] == "aaaaaaaaaaaaaa" {
return 0
}
return 1
}
func f11a(a []int, i int) {
useInt(a[i])
useInt(a[i]) // ERROR "Proved boolean IsInBounds$"
}
func f11b(a []int, i int) {
useSlice(a[i:])
useSlice(a[i:]) // ERROR "Proved boolean IsSliceInBounds$"
}
func f11c(a []int, i int) {
useSlice(a[:i])
useSlice(a[:i]) // ERROR "Proved boolean IsSliceInBounds$"
}
func f11d(a []int, i int) {
useInt(a[2*i+7])
useInt(a[2*i+7]) // ERROR "Proved boolean IsInBounds$"
}
func f12(a []int, b int) {
useSlice(a[:b])
}
func f13a(a, b, c int, x bool) int {
if a > 12 {
if x {
if a < 12 { // ERROR "Disproved Less64$"
return 1
}
}
if x {
if a <= 12 { // ERROR "Disproved Leq64$"
return 2
}
}
if x {
if a == 12 { // ERROR "Disproved Eq64$"
return 3
}
}
if x {
if a >= 12 { // ERROR "Proved Geq64$"
return 4
}
}
if x {
if a > 12 { // ERROR "Proved boolean Greater64$"
return 5
}
}
return 6
}
return 0
}
func f13b(a int, x bool) int {
if a == -9 {
if x {
if a < -9 { // ERROR "Disproved Less64$"
return 7
}
}
if x {
if a <= -9 { // ERROR "Proved Leq64$"
return 8
}
}
if x {
if a == -9 { // ERROR "Proved boolean Eq64$"
return 9
}
}
if x {
if a >= -9 { // ERROR "Proved Geq64$"
return 10
}
}
if x {
if a > -9 { // ERROR "Disproved Greater64$"
return 11
}
}
return 12
}
return 0
}
func f13c(a int, x bool) int {
if a < 90 {
if x {
if a < 90 { // ERROR "Proved boolean Less64$"
return 13
}
}
if x {
if a <= 90 { // ERROR "Proved Leq64$"
return 14
}
}
if x {
if a == 90 { // ERROR "Disproved Eq64$"
return 15
}
}
if x {
if a >= 90 { // ERROR "Disproved Geq64$"
return 16
}
}
if x {
if a > 90 { // ERROR "Disproved Greater64$"
return 17
}
}
return 18
}
return 0
}
func f13d(a int) int {
if a < 5 {
if a < 9 { // ERROR "Proved Less64$"
return 1
}
}
return 0
}
func f13e(a int) int {
if a > 9 {
if a > 5 { // ERROR "Proved Greater64$"
return 1
}
}
return 0
}
func f13f(a int64) int64 {
if a > math.MaxInt64 {
// Unreachable, but prove doesn't know that.
if a == 0 {
return 1
}
}
return 0
}
func f13g(a int) int {
if a < 3 {
return 5
}
if a > 3 {
return 6
}
if a == 3 { // ERROR "Proved Eq64$"
return 7
}
return 8
}
func f13h(a int) int {
if a < 3 {
if a > 1 {
if a == 2 { // ERROR "Proved Eq64$"
return 5
}
}
}
return 0
}
func f13i(a uint) int {
if a == 0 {
return 1
}
if a > 0 { // ERROR "Proved Greater64U$"
return 2
}
return 3
}
func f14(p, q *int, a []int) {
// This crazy ordering usually gives i1 the lowest value ID,
// j the middle value ID, and i2 the highest value ID.
// That used to confuse CSE because it ordered the args
// of the two + ops below differently.
// That in turn foiled bounds check elimination.
i1 := *p
j := *q
i2 := *p
useInt(a[i1+j])
useInt(a[i2+j]) // ERROR "Proved boolean IsInBounds$"
}
func f15(s []int, x int) {
useSlice(s[x:])
useSlice(s[:x]) // ERROR "Proved IsSliceInBounds$"
}
func f16(s []int) []int {
if len(s) >= 10 {
return s[:10] // ERROR "Proved non-negative bounds IsSliceInBounds$"
}
return nil
}
//go:noinline
func useInt(a int) {
}
//go:noinline
func useSlice(a []int) {
}
func main() {
}
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