mirror of
https://github.com/golang/go
synced 2024-11-18 13:44:48 -07:00
73f92f9b04
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>
117 lines
2.3 KiB
Go
117 lines
2.3 KiB
Go
// +build amd64
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// errorcheck -0 -d=ssa/check_bce/debug=3
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package main
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func f0(a []int) {
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a[0] = 1 // ERROR "Found IsInBounds$"
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a[0] = 1
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a[6] = 1 // ERROR "Found IsInBounds$"
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a[6] = 1
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a[5] = 1
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a[5] = 1
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}
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func f1(a [256]int, i int) {
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useInt(a[i]) // ERROR "Found IsInBounds$"
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useInt(a[i%256]) // ERROR "Found IsInBounds$"
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useInt(a[i&255])
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useInt(a[i&17])
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if 4 <= i && i < len(a) {
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useInt(a[i])
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useInt(a[i-1]) // ERROR "Found IsInBounds$"
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// TODO: 'if 4 <= i && i < len(a)' gets rewritten to 'if uint(i - 4) < 256 - 4',
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// which the bounds checker cannot yet use to infer that the next line doesn't need a bounds check.
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useInt(a[i-4])
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}
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}
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func f2(a [256]int, i uint) {
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useInt(a[i]) // ERROR "Found IsInBounds$"
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useInt(a[i%256])
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useInt(a[i&255])
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useInt(a[i&17])
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}
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func f3(a [256]int, i uint8) {
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useInt(a[i])
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useInt(a[i+10])
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useInt(a[i+14])
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}
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func f4(a [27]int, i uint8) {
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useInt(a[i%15])
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useInt(a[i%19])
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useInt(a[i%27])
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}
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func f5(a []int) {
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if len(a) > 5 {
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useInt(a[5])
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useSlice(a[6:])
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useSlice(a[:6])
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}
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}
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func f6(a [32]int, b [64]int, i int) {
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useInt(a[uint32(i*0x07C4ACDD)>>27])
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useInt(b[uint64(i*0x07C4ACDD)>>58])
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useInt(a[uint(i*0x07C4ACDD)>>59])
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// The following bounds should not be removed because they can overflow.
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useInt(a[uint32(i*0x106297f105d0cc86)>>26]) // ERROR "Found IsInBounds$"
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useInt(b[uint64(i*0x106297f105d0cc86)>>57]) // ERROR "Found IsInBounds$"
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useInt(a[int32(i*0x106297f105d0cc86)>>26]) // ERROR "Found IsInBounds$"
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useInt(b[int64(i*0x106297f105d0cc86)>>57]) // ERROR "Found IsInBounds$"
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}
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func g1(a []int) {
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for i := range a {
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a[i] = i
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useSlice(a[:i+1])
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useSlice(a[:i])
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}
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}
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func g2(a []int) {
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useInt(a[3]) // ERROR "Found IsInBounds$"
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useInt(a[2])
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useInt(a[1])
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useInt(a[0])
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}
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func g3(a []int) {
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for i := range a[:256] { // ERROR "Found IsSliceInBounds$"
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useInt(a[i]) // ERROR "Found IsInBounds$"
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}
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b := a[:256]
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for i := range b {
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useInt(b[i])
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}
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}
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func g4(a [100]int) {
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for i := 10; i < 50; i++ {
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useInt(a[i-10])
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useInt(a[i])
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useInt(a[i+25])
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useInt(a[i+50])
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// The following are out of bounds.
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useInt(a[i-11]) // ERROR "Found IsInBounds$"
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useInt(a[i+51]) // ERROR "Found IsInBounds$"
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}
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}
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//go:noinline
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func useInt(a int) {
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}
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//go:noinline
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func useSlice(a []int) {
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}
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func main() {
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}
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