mirror of
https://github.com/golang/go
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![Keith Randall](/assets/img/avatar_default.png)
Convert the scheduling pass from scheduling backwards to scheduling forwards. Forward scheduling makes it easier to prioritize scheduling values as soon as they are ready, which is important for things like nil checks, select ops, etc. Forward scheduling is also quite a bit clearer. It was originally backwards because computing uses is tricky, but I found a way to do it simply and with n lg n complexity. The new scheme also makes it easy to add new scheduling edges if needed. Fixes #42673 Update #56568 Change-Id: Ibbb38c52d191f50ce7a94f8c1cbd3cd9b614ea8b Reviewed-on: https://go-review.googlesource.com/c/go/+/270940 TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Keith Randall <khr@google.com> Run-TryBot: Keith Randall <khr@golang.org> Reviewed-by: David Chase <drchase@google.com>
251 lines
5.5 KiB
Go
251 lines
5.5 KiB
Go
// errorcheck -0 -d=nil
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// +build !wasm
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// +build !aix
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// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Test that nil checks are removed.
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// Optimization is enabled.
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package p
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type Struct struct {
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X int
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Y float64
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}
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type BigStruct struct {
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X int
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Y float64
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A [1 << 20]int
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Z string
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}
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type Empty struct {
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}
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type Empty1 struct {
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Empty
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}
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var (
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intp *int
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arrayp *[10]int
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array0p *[0]int
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bigarrayp *[1 << 26]int
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structp *Struct
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bigstructp *BigStruct
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emptyp *Empty
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empty1p *Empty1
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)
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func f1() {
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_ = *intp // ERROR "generated nil check"
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// This one should be removed but the block copy needs
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// to be turned into its own pseudo-op in order to see
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// the indirect.
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_ = *arrayp // ERROR "generated nil check"
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// 0-byte indirect doesn't suffice.
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// we don't registerize globals, so there are no removed.* nil checks.
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_ = *array0p // ERROR "generated nil check"
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_ = *array0p // ERROR "removed nil check"
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_ = *intp // ERROR "removed nil check"
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_ = *arrayp // ERROR "removed nil check"
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_ = *structp // ERROR "generated nil check"
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_ = *emptyp // ERROR "generated nil check"
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_ = *arrayp // ERROR "removed nil check"
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}
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func f2() {
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var (
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intp *int
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arrayp *[10]int
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array0p *[0]int
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bigarrayp *[1 << 20]int
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structp *Struct
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bigstructp *BigStruct
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emptyp *Empty
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empty1p *Empty1
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)
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_ = *intp // ERROR "generated nil check"
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_ = *arrayp // ERROR "generated nil check"
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_ = *array0p // ERROR "generated nil check"
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_ = *array0p // ERROR "removed.* nil check"
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_ = *intp // ERROR "removed.* nil check"
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_ = *arrayp // ERROR "removed.* nil check"
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_ = *structp // ERROR "generated nil check"
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_ = *emptyp // ERROR "generated nil check"
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_ = *arrayp // ERROR "removed.* nil check"
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_ = *bigarrayp // ERROR "generated nil check" ARM removed nil check before indirect!!
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_ = *bigstructp // ERROR "generated nil check"
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_ = *empty1p // ERROR "generated nil check"
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}
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func fx10k() *[10000]int
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var b bool
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func f3(x *[10000]int) {
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// Using a huge type and huge offsets so the compiler
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// does not expect the memory hardware to fault.
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_ = x[9999] // ERROR "generated nil check"
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for {
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if x[9999] != 0 { // ERROR "removed nil check"
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break
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}
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}
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x = fx10k()
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_ = x[9999] // ERROR "generated nil check"
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if b {
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_ = x[9999] // ERROR "removed.* nil check"
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} else {
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_ = x[9999] // ERROR "removed.* nil check"
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}
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_ = x[9999] // ERROR "removed nil check"
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x = fx10k()
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if b {
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_ = x[9999] // ERROR "generated nil check"
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} else {
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_ = x[9999] // ERROR "generated nil check"
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}
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_ = x[9999] // ERROR "generated nil check"
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fx10k()
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// This one is a bit redundant, if we figured out that
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// x wasn't going to change across the function call.
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// But it's a little complex to do and in practice doesn't
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// matter enough.
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_ = x[9999] // ERROR "removed nil check"
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}
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func f3a() {
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x := fx10k()
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y := fx10k()
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z := fx10k()
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_ = &x[9] // ERROR "generated nil check"
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y = z
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_ = &x[9] // ERROR "removed.* nil check"
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x = y
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_ = &x[9] // ERROR "generated nil check"
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}
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func f3b() {
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x := fx10k()
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y := fx10k()
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_ = &x[9] // ERROR "generated nil check"
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y = x
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_ = &x[9] // ERROR "removed.* nil check"
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x = y
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_ = &x[9] // ERROR "removed.* nil check"
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}
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func fx10() *[10]int
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func f4(x *[10]int) {
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// Most of these have no checks because a real memory reference follows,
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// and the offset is small enough that if x is nil, the address will still be
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// in the first unmapped page of memory.
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_ = x[9] // ERROR "generated nil check" // bug: would like to remove this check (but nilcheck and load are in different blocks)
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for {
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if x[9] != 0 { // ERROR "removed nil check"
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break
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}
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}
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x = fx10()
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_ = x[9] // ERROR "generated nil check" // bug would like to remove before indirect
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if b {
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_ = x[9] // ERROR "removed nil check"
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} else {
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_ = x[9] // ERROR "removed nil check"
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}
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_ = x[9] // ERROR "removed nil check"
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x = fx10()
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if b {
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_ = x[9] // ERROR "generated nil check" // bug would like to remove before indirect
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} else {
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_ = &x[9] // ERROR "generated nil check"
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}
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_ = x[9] // ERROR "generated nil check" // bug would like to remove before indirect
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fx10()
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_ = x[9] // ERROR "removed nil check"
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x = fx10()
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y := fx10()
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_ = &x[9] // ERROR "generated nil check"
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y = x
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_ = &x[9] // ERROR "removed[a-z ]* nil check"
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x = y
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_ = &x[9] // ERROR "removed[a-z ]* nil check"
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}
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func m1(m map[int][80]byte) byte {
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v := m[3] // ERROR "removed nil check"
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return v[5]
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}
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func m2(m map[int][800]byte) byte {
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v := m[3] // ERROR "removed nil check"
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return v[5]
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}
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func m3(m map[int][80]byte) (byte, bool) {
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v, ok := m[3] // ERROR "removed nil check"
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return v[5], ok
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}
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func m4(m map[int][800]byte) (byte, bool) {
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v, ok := m[3] // ERROR "removed nil check"
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return v[5], ok
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}
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func p1() byte {
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p := new([100]byte)
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return p[5] // ERROR "removed nil check"
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}
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type SS struct {
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x byte
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}
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type TT struct {
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SS
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}
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func f(t *TT) *byte {
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// See issue 17242.
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s := &t.SS // ERROR "generated nil check"
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return &s.x // ERROR "removed nil check"
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}
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// make sure not to do nil check for newobject
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func f7() (*Struct, float64) {
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t := new(Struct)
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p := &t.Y // ERROR "removed nil check"
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return t, *p // ERROR "removed nil check"
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}
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func f9() []int {
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x := new([1]int)
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x[0] = 1 // ERROR "removed nil check"
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y := x[:] // ERROR "removed nil check"
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return y
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}
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// See issue 42673.
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func f10(p **int) int {
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return * // ERROR "removed nil check"
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/* */
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*p // ERROR "removed nil check"
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}
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