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go/test/live.go
Keith Randall 908499adec cmd/compile: stop using VARKILL 
With the introduction of stack objects, VARKILL information is
no longer needed.

With stack objects, an object is dead when there are no more static
references to it, and the stack scanner can't find any live pointers
to it. VARKILL information isn't used to establish live ranges for
address-taken variables any more. In effect, the last static reference
*is* the VARKILL, and there's an additional dynamic liveness check
during stack scanning.

Next CL will actually rip out the VARKILL opcodes.

Change-Id: I030a2ab867445cf4e0e69397911f8a2e2f0ed07b
Reviewed-on: https://go-review.googlesource.com/c/go/+/419234
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
2022-08-18 17:36:38 +00:00

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// errorcheckwithauto -0 -l -live -wb=0 -d=ssa/insert_resched_checks/off
//go:build !ppc64 && !ppc64le && !goexperiment.regabiargs
// +build !ppc64,!ppc64le,!goexperiment.regabiargs
// ppc64 needs a better tighten pass to make f18 pass
// rescheduling checks need to be turned off because there are some live variables across the inserted check call
//
// For register ABI, liveness info changes slightly. See live_regabi.go.
// Copyright 2014 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.
// liveness tests with inlining disabled.
// see also live2.go.
package main
func printnl()
//go:noescape
func printpointer(**int)
//go:noescape
func printintpointer(*int)
//go:noescape
func printstringpointer(*string)
//go:noescape
func printstring(string)
//go:noescape
func printbytepointer(*byte)
func printint(int)
func f1() {
var x *int // ERROR "stack object x \*int$"
printpointer(&x) // ERROR "live at call to printpointer: x$"
printpointer(&x)
}
func f2(b bool) {
if b {
printint(0) // nothing live here
return
}
var x *int // ERROR "stack object x \*int$"
printpointer(&x) // ERROR "live at call to printpointer: x$"
printpointer(&x)
}
func f3(b1, b2 bool) {
// Here x and y are ambiguously live. In previous go versions they
// were marked as live throughout the function to avoid being
// poisoned in GODEBUG=gcdead=1 mode; this is now no longer the
// case.
printint(0)
if b1 == false {
printint(0)
return
}
if b2 {
var x *int // ERROR "stack object x \*int$"
printpointer(&x) // ERROR "live at call to printpointer: x$"
printpointer(&x)
} else {
var y *int // ERROR "stack object y \*int$"
printpointer(&y) // ERROR "live at call to printpointer: y$"
printpointer(&y)
}
printint(0) // nothing is live here
}
// The old algorithm treated x as live on all code that
// could flow to a return statement, so it included the
// function entry and code above the declaration of x
// but would not include an indirect use of x in an infinite loop.
// Check that these cases are handled correctly.
func f4(b1, b2 bool) { // x not live here
if b2 {
printint(0) // x not live here
return
}
var z **int
x := new(int) // ERROR "stack object x \*int$"
*x = 42
z = &x
printint(**z) // ERROR "live at call to printint: x$"
if b2 {
printint(1) // x not live here
return
}
for {
printint(**z) // ERROR "live at call to printint: x$"
}
}
func f5(b1 bool) {
var z **int
if b1 {
x := new(int) // ERROR "stack object x \*int$"
*x = 42
z = &x
} else {
y := new(int) // ERROR "stack object y \*int$"
*y = 54
z = &y
}
printint(**z) // nothing live here
}
// confusion about the _ result used to cause spurious "live at entry to f6: _".
func f6() (_, y string) {
y = "hello"
return
}
// confusion about addressed results used to cause "live at entry to f7: x".
func f7() (x string) { // ERROR "stack object x string"
_ = &x
x = "hello"
return
}
// ignoring block returns used to cause "live at entry to f8: x, y".
func f8() (x, y string) {
return g8()
}
func g8() (string, string)
// ignoring block assignments used to cause "live at entry to f9: x"
// issue 7205
var i9 interface{}
func f9() bool {
g8()
x := i9
y := interface{}(g18()) // ERROR "live at call to convT: x.data$" "live at call to g18: x.data$" "stack object .autotmp_[0-9]+ \[2\]string$"
i9 = y // make y escape so the line above has to call convT
return x != y
}
// liveness formerly confused by UNDEF followed by RET,
// leading to "live at entry to f10: ~r1" (unnamed result).
func f10() string {
panic(1)
}
// liveness formerly confused by select, thinking runtime.selectgo
// can return to next instruction; it always jumps elsewhere.
// note that you have to use at least two cases in the select
// to get a true select; smaller selects compile to optimized helper functions.
var c chan *int
var b bool
// this used to have a spurious "live at entry to f11a: ~r0"
func f11a() *int {
select { // ERROR "stack object .autotmp_[0-9]+ \[2\]struct"
case <-c:
return nil
case <-c:
return nil
}
}
func f11b() *int {
p := new(int)
if b {
// At this point p is dead: the code here cannot
// get to the bottom of the function.
// This used to have a spurious "live at call to printint: p".
printint(1) // nothing live here!
select { // ERROR "stack object .autotmp_[0-9]+ \[2\]struct"
case <-c:
return nil
case <-c:
return nil
}
}
println(*p)
return nil
}
var sink *int
func f11c() *int {
p := new(int)
sink = p // prevent stack allocation, otherwise p is rematerializeable
if b {
// Unlike previous, the cases in this select fall through,
// so we can get to the println, so p is not dead.
printint(1) // ERROR "live at call to printint: p$"
select { // ERROR "live at call to selectgo: p$" "stack object .autotmp_[0-9]+ \[2\]struct"
case <-c:
case <-c:
}
}
println(*p)
return nil
}
// similarly, select{} does not fall through.
// this used to have a spurious "live at entry to f12: ~r0".
func f12() *int {
if b {
select {}
} else {
return nil
}
}
// incorrectly placed VARDEF annotations can cause missing liveness annotations.
// this used to be missing the fact that s is live during the call to g13 (because it is
// needed for the call to h13).
func f13() {
s := g14()
s = h13(s, g13(s)) // ERROR "live at call to g13: s.ptr$"
}
func g13(string) string
func h13(string, string) string
// more incorrectly placed VARDEF.
func f14() {
x := g14() // ERROR "stack object x string$"
printstringpointer(&x)
}
func g14() string
// Checking that various temporaries do not persist or cause
// ambiguously live values that must be zeroed.
// The exact temporary names are inconsequential but we are
// trying to check that there is only one at any given site,
// and also that none show up in "ambiguously live" messages.
var m map[string]int
var mi map[interface{}]int
// str and iface are used to ensure that a temp is required for runtime calls below.
func str() string
func iface() interface{}
func f16() {
if b {
delete(mi, iface()) // ERROR "stack object .autotmp_[0-9]+ interface \{\}$"
}
delete(mi, iface())
delete(mi, iface())
}
var m2s map[string]*byte
var m2 map[[2]string]*byte
var x2 [2]string
var bp *byte
func f17a(p *byte) { // ERROR "live at entry to f17a: p$"
if b {
m2[x2] = p // ERROR "live at call to mapassign: p$"
}
m2[x2] = p // ERROR "live at call to mapassign: p$"
m2[x2] = p // ERROR "live at call to mapassign: p$"
}
func f17b(p *byte) { // ERROR "live at entry to f17b: p$"
// key temporary
if b {
m2s[str()] = p // ERROR "live at call to mapassign_faststr: p$" "live at call to str: p$"
}
m2s[str()] = p // ERROR "live at call to mapassign_faststr: p$" "live at call to str: p$"
m2s[str()] = p // ERROR "live at call to mapassign_faststr: p$" "live at call to str: p$"
}
func f17c() {
// key and value temporaries
if b {
m2s[str()] = f17d() // ERROR "live at call to f17d: .autotmp_[0-9]+$" "live at call to mapassign_faststr: .autotmp_[0-9]+$"
}
m2s[str()] = f17d() // ERROR "live at call to f17d: .autotmp_[0-9]+$" "live at call to mapassign_faststr: .autotmp_[0-9]+$"
m2s[str()] = f17d() // ERROR "live at call to f17d: .autotmp_[0-9]+$" "live at call to mapassign_faststr: .autotmp_[0-9]+$"
}
func f17d() *byte
func g18() [2]string
func f18() {
// key temporary for mapaccess.
// temporary introduced by orderexpr.
var z *byte
if b {
z = m2[g18()] // ERROR "stack object .autotmp_[0-9]+ \[2\]string$"
}
z = m2[g18()]
z = m2[g18()]
printbytepointer(z)
}
var ch chan *byte
// byteptr is used to ensure that a temp is required for runtime calls below.
func byteptr() *byte
func f19() {
// dest temporary for channel receive.
var z *byte
if b {
z = <-ch // ERROR "stack object .autotmp_[0-9]+ \*byte$"
}
z = <-ch
z = <-ch // ERROR "live at call to chanrecv1: .autotmp_[0-9]+$"
printbytepointer(z)
}
func f20() {
// src temporary for channel send
if b {
ch <- byteptr() // ERROR "stack object .autotmp_[0-9]+ \*byte$"
}
ch <- byteptr()
ch <- byteptr()
}
func f21() {
// key temporary for mapaccess using array literal key.
var z *byte
if b {
z = m2[[2]string{"x", "y"}] // ERROR "stack object .autotmp_[0-9]+ \[2\]string$"
}
z = m2[[2]string{"x", "y"}]
z = m2[[2]string{"x", "y"}]
printbytepointer(z)
}
func f23() {
// key temporary for two-result map access using array literal key.
var z *byte
var ok bool
if b {
z, ok = m2[[2]string{"x", "y"}] // ERROR "stack object .autotmp_[0-9]+ \[2\]string$"
}
z, ok = m2[[2]string{"x", "y"}]
z, ok = m2[[2]string{"x", "y"}]
printbytepointer(z)
print(ok)
}
func f24() {
// key temporary for map access using array literal key.
// value temporary too.
if b {
m2[[2]string{"x", "y"}] = nil // ERROR "stack object .autotmp_[0-9]+ \[2\]string$"
}
m2[[2]string{"x", "y"}] = nil
m2[[2]string{"x", "y"}] = nil
}
// Non-open-coded defers should not cause autotmps. (Open-coded defers do create extra autotmps).
func f25(b bool) {
for i := 0; i < 2; i++ {
// Put in loop to make sure defer is not open-coded
defer g25()
}
if b {
return
}
var x string
x = g14()
printstring(x)
return
}
func g25()
// non-escaping ... slices passed to function call should die on return,
// so that the temporaries do not stack and do not cause ambiguously
// live variables.
func f26(b bool) {
if b {
print26((*int)(nil), (*int)(nil), (*int)(nil)) // ERROR "stack object .autotmp_[0-9]+ \[3\]interface \{\}$"
}
print26((*int)(nil), (*int)(nil), (*int)(nil))
print26((*int)(nil), (*int)(nil), (*int)(nil))
printnl()
}
//go:noescape
func print26(...interface{})
// non-escaping closures passed to function call should die on return
func f27(b bool) {
x := 0
if b {
call27(func() { x++ }) // ERROR "stack object .autotmp_[0-9]+ struct \{"
}
call27(func() { x++ })
call27(func() { x++ })
printnl()
}
// but defer does escape to later execution in the function
func f27defer(b bool) {
x := 0
if b {
defer call27(func() { x++ }) // ERROR "stack object .autotmp_[0-9]+ struct \{"
}
defer call27(func() { x++ }) // ERROR "stack object .autotmp_[0-9]+ struct \{"
printnl() // ERROR "live at call to printnl: .autotmp_[0-9]+ .autotmp_[0-9]+"
return // ERROR "live at indirect call: .autotmp_[0-9]+"
}
// and newproc (go) escapes to the heap
func f27go(b bool) {
x := 0
if b {
go call27(func() { x++ }) // ERROR "live at call to newobject: &x$" "live at call to newobject: &x .autotmp_[0-9]+$" "live at call to newproc: &x$" // allocate two closures, the func literal, and the wrapper for go
}
go call27(func() { x++ }) // ERROR "live at call to newobject: &x$" "live at call to newobject: .autotmp_[0-9]+$" // allocate two closures, the func literal, and the wrapper for go
printnl()
}
//go:noescape
func call27(func())
// concatstring slice should die on return
var s1, s2, s3, s4, s5, s6, s7, s8, s9, s10 string
func f28(b bool) {
if b {
printstring(s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8 + s9 + s10) // ERROR "stack object .autotmp_[0-9]+ \[10\]string$"
}
printstring(s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8 + s9 + s10)
printstring(s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8 + s9 + s10)
}
// map iterator should die on end of range loop
func f29(b bool) {
if b {
for k := range m { // ERROR "live at call to mapiterinit: .autotmp_[0-9]+$" "live at call to mapiternext: .autotmp_[0-9]+$" "stack object .autotmp_[0-9]+ map.iter\[string\]int$"
printstring(k) // ERROR "live at call to printstring: .autotmp_[0-9]+$"
}
}
for k := range m { // ERROR "live at call to mapiterinit: .autotmp_[0-9]+$" "live at call to mapiternext: .autotmp_[0-9]+$"
printstring(k) // ERROR "live at call to printstring: .autotmp_[0-9]+$"
}
for k := range m { // ERROR "live at call to mapiterinit: .autotmp_[0-9]+$" "live at call to mapiternext: .autotmp_[0-9]+$"
printstring(k) // ERROR "live at call to printstring: .autotmp_[0-9]+$"
}
}
// copy of array of pointers should die at end of range loop
var pstructarr [10]pstruct
// Struct size chosen to make pointer to element in pstructarr
// not computable by strength reduction.
type pstruct struct {
intp *int
_ [8]byte
}
func f30(b bool) {
// live temp during printintpointer(p):
// the internal iterator pointer if a pointer to pstruct in pstructarr
// can not be easily computed by strength reduction.
if b {
for _, p := range pstructarr { // ERROR "stack object .autotmp_[0-9]+ \[10\]pstruct$"
printintpointer(p.intp) // ERROR "live at call to printintpointer: .autotmp_[0-9]+$"
}
}
for _, p := range pstructarr {
printintpointer(p.intp) // ERROR "live at call to printintpointer: .autotmp_[0-9]+$"
}
for _, p := range pstructarr {
printintpointer(p.intp) // ERROR "live at call to printintpointer: .autotmp_[0-9]+$"
}
}
// conversion to interface should not leave temporary behind
func f31(b1, b2, b3 bool) {
if b1 {
g31(g18()) // ERROR "stack object .autotmp_[0-9]+ \[2\]string$"
}
if b2 {
h31(g18()) // ERROR "live at call to convT: .autotmp_[0-9]+$" "live at call to newobject: .autotmp_[0-9]+$"
}
if b3 {
panic(g18())
}
print(b3)
}
func g31(interface{})
func h31(...interface{})
// non-escaping partial functions passed to function call should die on return
type T32 int
func (t *T32) Inc() { // ERROR "live at entry to \(\*T32\).Inc: t$"
*t++
}
var t32 T32
func f32(b bool) {
if b {
call32(t32.Inc) // ERROR "stack object .autotmp_[0-9]+ struct \{"
}
call32(t32.Inc)
call32(t32.Inc)
}
//go:noescape
func call32(func())
// temporaries introduced during if conditions and && || expressions
// should die once the condition has been acted upon.
var m33 map[interface{}]int
func f33() {
if m33[byteptr()] == 0 { // ERROR "stack object .autotmp_[0-9]+ interface \{\}$"
printnl()
return
} else {
printnl()
}
printnl()
}
func f34() {
if m33[byteptr()] == 0 { // ERROR "stack object .autotmp_[0-9]+ interface \{\}$"
printnl()
return
}
printnl()
}
func f35() {
if m33[byteptr()] == 0 && // ERROR "stack object .autotmp_[0-9]+ interface \{\}"
m33[byteptr()] == 0 { // ERROR "stack object .autotmp_[0-9]+ interface \{\}"
printnl()
return
}
printnl()
}
func f36() {
if m33[byteptr()] == 0 || // ERROR "stack object .autotmp_[0-9]+ interface \{\}"
m33[byteptr()] == 0 { // ERROR "stack object .autotmp_[0-9]+ interface \{\}"
printnl()
return
}
printnl()
}
func f37() {
if (m33[byteptr()] == 0 || // ERROR "stack object .autotmp_[0-9]+ interface \{\}"
m33[byteptr()] == 0) && // ERROR "stack object .autotmp_[0-9]+ interface \{\}"
m33[byteptr()] == 0 {
printnl()
return
}
printnl()
}
// select temps should disappear in the case bodies
var c38 chan string
func fc38() chan string
func fi38(int) *string
func fb38() *bool
func f38(b bool) {
// we don't care what temps are printed on the lines with output.
// we care that the println lines have no live variables
// and therefore no output.
if b {
select { // ERROR "live at call to selectgo:( .autotmp_[0-9]+)+$" "stack object .autotmp_[0-9]+ \[4\]struct \{"
case <-fc38():
printnl()
case fc38() <- *fi38(1): // ERROR "live at call to fc38:( .autotmp_[0-9]+)+$" "live at call to fi38:( .autotmp_[0-9]+)+$" "stack object .autotmp_[0-9]+ string$"
printnl()
case *fi38(2) = <-fc38(): // ERROR "live at call to fc38:( .autotmp_[0-9]+)+$" "live at call to fi38:( .autotmp_[0-9]+)+$" "stack object .autotmp_[0-9]+ string$"
printnl()
case *fi38(3), *fb38() = <-fc38(): // ERROR "stack object .autotmp_[0-9]+ string$" "live at call to f[ibc]38:( .autotmp_[0-9]+)+$"
printnl()
}
printnl()
}
printnl()
}
// issue 8097: mishandling of x = x during return.
func f39() (x []int) {
x = []int{1}
printnl() // ERROR "live at call to printnl: .autotmp_[0-9]+$"
return x
}
func f39a() (x []int) {
x = []int{1}
printnl() // ERROR "live at call to printnl: .autotmp_[0-9]+$"
return
}
func f39b() (x [10]*int) {
x = [10]*int{}
x[0] = new(int) // ERROR "live at call to newobject: x$"
printnl() // ERROR "live at call to printnl: x$"
return x
}
func f39c() (x [10]*int) {
x = [10]*int{}
x[0] = new(int) // ERROR "live at call to newobject: x$"
printnl() // ERROR "live at call to printnl: x$"
return
}
// issue 8142: lost 'addrtaken' bit on inlined variables.
// no inlining in this test, so just checking that non-inlined works.
type T40 struct {
m map[int]int
}
//go:noescape
func useT40(*T40)
func newT40() *T40 {
ret := T40{}
ret.m = make(map[int]int, 42) // ERROR "live at call to makemap: &ret$"
return &ret
}
func bad40() {
t := newT40()
_ = t
printnl()
}
func good40() {
ret := T40{} // ERROR "stack object ret T40$"
ret.m = make(map[int]int) // ERROR "live at call to fastrand: .autotmp_[0-9]+$" "stack object .autotmp_[0-9]+ map.hdr\[int\]int$"
t := &ret
printnl() // ERROR "live at call to printnl: ret$"
// Note: ret is live at the printnl because the compiler moves &ret
// from before the printnl to after.
useT40(t)
}
func ddd1(x, y *int) { // ERROR "live at entry to ddd1: x y$"
ddd2(x, y) // ERROR "stack object .autotmp_[0-9]+ \[2\]\*int$"
printnl()
// Note: no .?autotmp live at printnl. See issue 16996.
}
func ddd2(a ...*int) { // ERROR "live at entry to ddd2: a$"
sink = a[0]
}
// issue 16016: autogenerated wrapper should have arguments live
type T struct{}
func (*T) Foo(ptr *int) {}
type R struct{ *T }
// issue 18860: output arguments must be live all the time if there is a defer.
// In particular, at printint r must be live.
func f41(p, q *int) (r *int) { // ERROR "live at entry to f41: p q$"
r = p
defer func() {
recover()
}()
printint(0) // ERROR "live at call to printint: q r .autotmp_[0-9]+$"
r = q
return // ERROR "live at call to f41.func1: r .autotmp_[0-9]+$"
}
func f42() {
var p, q, r int
f43([]*int{&p, &q, &r}) // ERROR "stack object .autotmp_[0-9]+ \[3\]\*int$"
f43([]*int{&p, &r, &q})
f43([]*int{&q, &p, &r})
}
//go:noescape
func f43(a []*int)
// Assigning to a sub-element that makes up an entire local variable
// should clobber that variable.
func f44(f func() [2]*int) interface{} { // ERROR "live at entry to f44: f"
type T struct {
s [1][2]*int
}
ret := T{} // ERROR "stack object ret T"
ret.s[0] = f()
return ret
}
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