go/test/prove.go

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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 {
cmd/compile/internal/ssa: BCE for induction variables There are 5293 loop in the main go repository. A survey of the top most common for loops: 18 for __k__ := 0; i < len(sa.Addr); i++ { 19 for __k__ := 0; ; i++ { 19 for __k__ := 0; i < 16; i++ { 25 for __k__ := 0; i < length; i++ { 30 for __k__ := 0; i < 8; i++ { 49 for __k__ := 0; i < len(s); i++ { 67 for __k__ := 0; i < n; i++ { 376 for __k__ := range __slice__ { 685 for __k__, __v__ := range __slice__ { 2074 for __, __v__ := range __slice__ { The algorithm to find induction variables handles all cases with an upper limit. It currently doesn't find related induction variables such as c * ind or c + ind. 842 out of 22954 bound checks are removed for src/make.bash. 1957 out of 42952 bounds checks are removed for src/all.bash. Things to do in follow-up CLs: * Find the associated pointer for `for _, v := range a {}` * Drop the NilChecks on the pointer. * Replace the implicit induction variable by a loop over the pointer Generated garbage can be reduced if we share the sdom between passes. % benchstat old.txt new.txt name old time/op new time/op delta Template 337ms ± 3% 333ms ± 3% ~ (p=0.258 n=9+9) GoTypes 1.11s ± 2% 1.10s ± 2% ~ (p=0.912 n=10+10) Compiler 5.25s ± 1% 5.29s ± 2% ~ (p=0.077 n=9+9) MakeBash 33.5s ± 1% 34.1s ± 2% +1.85% (p=0.011 n=9+9) name old alloc/op new alloc/op delta Template 63.6MB ± 0% 63.9MB ± 0% +0.52% (p=0.000 n=10+9) GoTypes 218MB ± 0% 219MB ± 0% +0.59% (p=0.000 n=10+9) Compiler 978MB ± 0% 985MB ± 0% +0.69% (p=0.000 n=10+10) name old allocs/op new allocs/op delta Template 582k ± 0% 583k ± 0% +0.10% (p=0.000 n=10+10) GoTypes 1.78M ± 0% 1.78M ± 0% +0.12% (p=0.000 n=10+10) Compiler 7.68M ± 0% 7.69M ± 0% +0.05% (p=0.000 n=10+10) name old text-bytes new text-bytes delta HelloSize 581k ± 0% 581k ± 0% -0.08% (p=0.000 n=10+10) CmdGoSize 6.40M ± 0% 6.39M ± 0% -0.08% (p=0.000 n=10+10) name old data-bytes new data-bytes delta HelloSize 3.66k ± 0% 3.66k ± 0% ~ (all samples are equal) CmdGoSize 134k ± 0% 134k ± 0% ~ (all samples are equal) name old bss-bytes new bss-bytes delta HelloSize 126k ± 0% 126k ± 0% ~ (all samples are equal) CmdGoSize 149k ± 0% 149k ± 0% ~ (all samples are equal) name old exe-bytes new exe-bytes delta HelloSize 947k ± 0% 946k ± 0% -0.01% (p=0.000 n=10+10) CmdGoSize 9.92M ± 0% 9.91M ± 0% -0.06% (p=0.000 n=10+10) Change-Id: Ie74bdff46fd602db41bb457333d3a762a0c3dc4d Reviewed-on: https://go-review.googlesource.com/20517 Reviewed-by: David Chase <drchase@google.com> Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
2016-03-02 11:58:27 +00:00
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)
cmd/compile: unroll comparisons to short constant strings Unroll s == "ab" to len(s) == 2 && s[0] == 'a' && s[1] == 'b' This generates faster and shorter code by avoiding a runtime call. Do something similar for !=. The cutoff length is 6. This was chosen empirically by examining binary sizes on arm, arm64, 386, and amd64 using the SSA backend. For all architectures examined, 4, 5, and 6 were the ideal cutoff, with identical binary sizes. The distribution of constant string equality sizes during 'go build -a std' is: 40.81% 622 len 0 14.11% 215 len 4 9.45% 144 len 1 7.81% 119 len 3 7.48% 114 len 5 5.12% 78 len 7 4.13% 63 len 2 3.54% 54 len 8 2.69% 41 len 6 1.18% 18 len 10 0.85% 13 len 9 0.66% 10 len 14 0.59% 9 len 17 0.46% 7 len 11 0.26% 4 len 12 0.20% 3 len 19 0.13% 2 len 13 0.13% 2 len 15 0.13% 2 len 16 0.07% 1 len 20 0.07% 1 len 23 0.07% 1 len 33 0.07% 1 len 36 A cutoff of length 6 covers most of the cases. Benchmarks on amd64 comparing a string to a constant of length 3: Cmp/1same-8 4.78ns ± 6% 0.94ns ± 9% -80.26% (p=0.000 n=20+20) Cmp/1diffbytes-8 6.43ns ± 6% 0.96ns ±11% -85.13% (p=0.000 n=20+20) Cmp/3same-8 4.71ns ± 5% 1.28ns ± 5% -72.90% (p=0.000 n=20+20) Cmp/3difffirstbyte-8 6.33ns ± 7% 1.27ns ± 7% -79.90% (p=0.000 n=20+20) Cmp/3difflastbyte-8 6.34ns ± 8% 1.26ns ± 9% -80.13% (p=0.000 n=20+20) The change to the prove test preserves the existing intent of the test. When the string was short, there was a new "proved in bounds" report that referred to individual byte comparisons. Change-Id: I593ac303b0d11f275672090c5c786ea0c6b8da13 Reviewed-on: https://go-review.googlesource.com/26758 Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2016-06-25 20:40:43 +00:00
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$"
}
//go:noinline
func useInt(a int) {
}
//go:noinline
func useSlice(a []int) {
}
func main() {
}