mirror of
https://github.com/golang/go
synced 2024-11-13 18:10:24 -07:00
aa0439ba65
This eliminates ~75% of the nil checks being emitted, on all architectures. We can do better, but we need a bit more general support from the compiler, and I don't want to do that so close to Go 1.2. What's here is simple but effective and safe. A few small code generation cleanups were required to make the analysis consistent on all systems about which nil checks are omitted, at least in the test. Fixes #6019. R=ken2 CC=golang-dev https://golang.org/cl/13334052
192 lines
4.3 KiB
Go
192 lines
4.3 KiB
Go
// errorcheck -0 -d=nil
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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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_ = *array0p // ERROR "generated nil check"
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_ = *array0p // ERROR "removed repeated nil check" 386
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_ = *intp // ERROR "removed repeated nil check"
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_ = *arrayp // ERROR "removed repeated 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 repeated 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 repeated nil check"
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_ = *intp // ERROR "removed repeated nil check"
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_ = *arrayp // ERROR "removed repeated 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 repeated 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 "generated 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 repeated nil check"
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} else {
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_ = x[9999] // ERROR "removed repeated nil check"
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}
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_ = x[9999] // ERROR "generated 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 "generated 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 repeated 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 repeated nil check"
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x = y
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_ = &x[9] // ERROR "removed repeated 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 "removed nil check before indirect"
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for {
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if x[9] != 0 { // ERROR "removed nil check before indirect"
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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 "removed nil check before indirect"
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if b {
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_ = x[9] // ERROR "removed nil check before indirect"
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} else {
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_ = x[9] // ERROR "removed nil check before indirect"
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}
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_ = x[9] // ERROR "removed nil check before indirect"
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x = fx10()
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if b {
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_ = x[9] // ERROR "removed nil check 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 "removed nil check before indirect"
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fx10()
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_ = x[9] // ERROR "removed nil check before indirect"
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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 repeated nil check"
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x = y
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_ = &x[9] // ERROR "removed repeated nil check"
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}
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